THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION (See section 10, rule 13) “STATE CHECKING DEVICE FOR EMBEDDED OBJECT, OPERATION CHECKING DEVICE, AND STATE CHECKING METHOD FOR EMBEDDED OBJECT” NABTESCO CORPORATION, of 7-9, Hirakawacho 2-chome, Chiyoda-ku, Tokyo 1020093, Japan The following specification particularly describes the invention and the manner in which it is to be performed. STATUS CHECKING DEVICE FOR BUILT.IN OBIECT, OPERATION CHECKING DEVICE, AND METHOD FOR CHECKING STATUS OF BUILT-IN OBIECT TECHNICAL FIELD [00011 The present invention relates to a status checking device for a built-in object, an operation checking devicg and a method for checking a status of a built-in object. BACKGROUND [0002] Conventionally, there has been proposed a technique in which physical information such as a stain, a temperature, or the like of an apparatus such as a speed reducer or a bearing built in an industial machine is detected by a sensor provided in said apparatus iBelf, and a status of the apparatus is monitored based on the thus detected physical information. For examph, fapanese Patent Application Publication No.2007-256033 (the'033 Publication) (detection of deterioration of a lubricant for a bearing used for a mechanical facility: examples of the mechanical facility include a belt conveyor and an axle shaft of a railway vehicle) discloses a system in which a foreign substance content in a lubricant for a bearing built in a mechanical facility is optically detected by a sensor provided in the bearing, and &terioration of the lubricant is &tected based on the thus detected foreign substance content in the lubricant. [00031 In inside and ouside of an apparatus built in an industial machine, howeve4 there is often no sufficient space for installing a sensor for monitoring a status of the -L- apparatus. Furthermore, since such a sensor requires a plurality of wirings for tansmitting a detection signal and for supplying electric powe[ in some cases, there is no space for wiring in an indusffial machine or wiring might interfere with an operation of an industrial machine and thus cannot be provided These issues become more conspicuous particularly in a case of monitoring an apparatus built in an indusfrial machine that has already been in use. Therefore, providing such a status monitoring sensor in an apparatus requires, for example, a size reduction of the senso[ a size increase of an industrial machine so that a sufficient space is allowed in the industial machine, or adoption of a battery or a wireless type. There are, howeve4, limitations also on a size reduction of a sensor and a size increase of an industial machine, and use of a battery requires replacement of the battery, while a wirehss type presenB a problem of antenna setup. [0004] For these reasons, in some cases, it is impossible to monitor or check a status of an apparatus that is built in an industial machine and cannot be directly accessed from ouBide. [0005] Furthermore, there is a similar problem with an internal status of a sffuctural member such as a steel frame or a reinforcing steel bar provided in an inside of a civil engineering or building structure such as a wind turbine for wind power generation, a heliostat of a solar thermal power generation towe4 an elevated road, a bridge, or a building, a fastening member such as a bolt provided in said inside, various types of piping for water supply and sewage and for electric wiring embedded inside, and concrete forming a civil engineering or building structure made of said concrete, such as a wind turbine for wind power generation, a solar thermal power generation towe4 an elevated road, a bridge, or a buiHing. -2- [00061 Moreove4, there is a similar problem also with a common groove, a water pipe, a gas pipe or the like buried under a road or a sidewalk, and a connection portion thereof. [00071 There is a similar problem further with, for examph, a structure such as a beam provided inside a vehicle body or a door of an automobih, a truck, a bus, a railway vehicle, or a civil engineering and constuction machine such as a hydraulic excavato4 inside a hull of a ship, or inside a fuselage of an aircraft, and a fastening member such as a bolt or a rivet. SUMMARY [0008] The present invention has been made in view of the foregoing and one object thereof is to provide a status checking device for a built-in object, an operation checking device, and a method for checking a status of a built-in object, which allow a status of an apparatus built in an industial machine to be monitored or checked without directly providing a sensor on the apparatus, the status of the apparatus being unable to be directly checked from oubide due to lack of means such as a duct that links an inside to an ouBide of the industrial machine. [009] The present invention provides a status checking device for a built-in object, which is provided with an information acquisition unit for acquiring at least one piece of physical information regarding an article including a target built therein, a status of the target being unabh to be directly checked from ouBide, the at least one piece of physical information being manifested ouBide the article, and a status determination unit for &termining the status of the target based on the acquired at least one piece of physical information. -3- [00101 In the status checking device according to the present invention, it may also be possible that the information acquisition unit acquires a plurality of pieces of physical information, and the status determination unit &termines a status of the target based on the acquired plurality of pieces of physical information. [00111 In the status checking device for a built-in object according to the present invention, it may also be possible that the status determination unit has an abnormality determination unit for determining whether the target is in an abnormal state. [00121 In the status checking device for a built-in object according to the present invention, it may also be possible that the status determination unit has an abnormality determination unit for determining whether the target is in the abnormal state based on at least one of a result of a comparison between the acquired plurality of pieces of physical information and abnormality determination threshoH values corresponding respectively to said plurality of pieces of physical information and a result of a comparison between a combination of the acquired plurality of pieces of physical information and a set of abnormality futermination threshold values corresponding to said combination of the plurality of pieces of physical information. [00131 In the status checking device for a built-in object according to the present invention, it may also be possibb that the status determination unit has a malfunction prediction unit for determining whether the target is in a state where a malfunction is predicted to occur within a predetermined time period [00141 In the status checking device for a built-in object according to the present invention, it may also be possible that the malfunction prediction unit determines whether the target is in the state where a malfunction is predicted to occur within a -4- predetermined time period based on at least one of a result of a comparison between the acquired plurality of pieces of physical information and malfunction prediction determination threshold values corresponding respectively to said plurality of pieces of physical information and a result of a comparison between a combination of the acquired plurality of pieces of physical information and a combination of malfunction prediction determination threshold values corresponding to said combination of the plurality of pieces of physical information. [00151 In the status checking &vice for a built-in object according to the present invention, it may also be possible that the status determination unit has a malfunction prediction unit for determining whether the target is in the state where a malfunction is predicted to occur within a predetermined time period based on a status determination model generated from history information of the acquired at least one piece of physical information. [0016] In the status checking device for a built-in object according to the present invention, it may also be possible that the status determination model is composed of two models, the two models being a malfunction state model generated from the history information as obtained when a malfunction has occurred in the target and a normal state model generated from the history information as obtained when a malfunction has not occurred in the target, and when the target is in a state more analogous to the malfunction state model than to the normal state model, it is determined that the target is in the state where a malfunction is predicted to occur within a predetermined time period [00171 In the status checking device for a built-in object according to the present invention, it may also be possible that the at hast one piece of physical information -5 manifested ouBide the article includes a piece of physical information regarding a surface of the article. [0018] In the status checking device for a built-in object according to the present invention, it may also be possible that the piece of physical information regarding the surface of the article includes at least one of properties of the surface of the article including a temperature, a position, a strain, a displacement, a vibration, a hue, a brightress, a saturation, a moisture content, an oil content, and a reflectance of a sound wave, ultrasoun{ infrared light, or any other type of light. [00191 In the status checking device for a built-in object according to the present invention, it may also be possible that the at least one piece of physical information manifested outside the article inclu&s at least one of a sound, an odor; ulffasound, an electromagnetic wave, radiation, and an emission, which are detected ouBide the article. [00201 In the status checking device for a built-in object according to the present invention, it may also be possible that the information acquisition unit acquires the piece of physical information based on a captured image of at least a part of the surface of the artich. [00211 In the status checking device for a built-in object according to the present invention, it may also be possible that a thermochromic member whose color changes depending on a temperature is provi&d on the surface of the article, and the information acquisition unit acquires a temperature of the surface of the article based on a captured image of the thermochromic member. lOO22l In the status checking device for a built-in object according to the present 6- invention, it may also be possible that the information acquisition unit has an enhrged image capturing function of capturing an enlarged image of at least a part of the surface of the article. [00231 In the status checking device for a built-in object according to the present invention, there may be further provided a drive unit for driving the information acquisition unit to change an image capturing range. lOO24l In the status checking device for a built-in object according to the present invention, it may also be possibh that the information acquisition unit has a plurality of cameras for capturing images of different areas on the surface of the object. [00251 In the status checking &vice for a built-in object according to the present invention, it may also be possibh that the plurality of cameras are disposed so as to surround the articb. [00261 In the status checking device for a built-in object according to the present invention, it may also be possible that the information acquisition unit has an optical system capable of wide-angle or omnidirectional image capturing. lOO27l In the status checking device for a built-in object according to the present invention, it may also be possible that the information acquisition unit has a drone equipped with a camera and a drone control unit for caphrring an image of the surface of the artich with the camera. [00281 In the status checking device for a built-in object according to the present invention, it may also be possibb that the information acquisition unit acquires a three-dimensional shape of at hast a part of the surface of the article based on the captured image, and acquires the piece of physical information based on the acquired -7 - three-dimensional shape [00291 In the status checking device for a built-in object according to the present invention, it may also be possible that the information acquisition unit is disposed away from the surface of the article and disposed at least above the artich. [00301 In the status checking device for a built-in object according to the present invention, it may also be possible that, by using a stahrs of the artich at a time of construction or installation as a criterion, the status determination unit for a built-in object determines whether or not the target is in an abnormal state or a state where a malfunction is predicted to occur within a predetermined time period [00311 In the status checking device for a built-in object according to the present invention, it may also be possible that the object is to be operated, and by using a status of the artich at a start of the operation as a criterion, it is determined whether or not the target is in an abnormal state or a state where a malfunction is predicted to occur within a predetermined time period [00321 In the status checking device for a built-in object according to the present invention, it may also be possible that in a case where a first piece of physical information agrees with a second piece of physical information, the first piece of physical information being acquired previously as a piece of physical information obtained when the target is in an abnormal state or a state where a malfunction is predicted to occur within a predetermined time period the second piece of physical information being acquired at any time by the information acquisition unit, the status determination unit determines that the target is in the abnormal state or the state where a malfunction is predicted to occur within a predetermined time period -B- [00331 In the status checking device for a built-in object according to the present invention, it may also be possible that the artich is an industial robot having at least one rotation shaft, the target is a speed reducer built in the rotation shaft, and the information acquisition unit acquires physical information regarding a surface of the rotation shaft. [0034] The present invention provides an operation checking device, which checks, in a virtual space on a compute4 an operation of an artich including a target built therein, a status of the target being unabh to be directly checked from ouEide. In the operation checking device, a status of the target acquired by the above-described status checking device for a built-in object is inputted as information related to a status of the article. [00351 The present invention provides a method for checking a status of a built-in object, which inclu&s steps of acquiring at hast one piece of physical information regarding an artich including a target built therein, a status of the target being unabh to be directly checked from oubide, the at least one piece of physical information being manifested ouBide the articb, and determining whether or not the target is in an abnormal state or a state where a malfunction is predicted to occur within a predetermined time period based on the acquire at least one piece of physical information. [0036] According to the present invention, it is possible to check a status of a target built in an object, which is unable to be directly checked from ouBide, without directly providing a sensor in the arget. BRIEF DESCRIPTION OF THE DRAWINGS -9- [00371 Fig. 1 is a block diagram showing an apparatus sahls monitoring device according to an embodiment of the present invention. Fig. 2 is a view showing a group of examples of an industrial machine to which the apparatus status monitoring device according to this embodiment is applicabh. Fig. 3 is a view showing another group of examples of the industrial machine to which the apparatus status monitoring device according to this embodiment is applicable. Fig. 4 is a block diagram showing a detail of an apparatus status determination unit in the apparatus status monitoring &vice according to this embodiment. Fig. 5 is a flow chart showing an operation example of the apparatus stah.ls monitoring device according to this embodiment. Fig. 6 is a block diagram showing an apparatus status monitoring device according to a first modification example of this embodiment. Fig.7 is a view showing an application example in which an apparatus status monitoring device according to a second modification example of this embodiment is applied to an industrial robot. Fig. 8 is a flow chart showing an operation examph of the apparatus status monitoring device according to the second modification example of this embodiment. Fig. 9 is an explanatory view for explaining a malfunction prediction process in the operation example of the apparahrs status monitoring device according to the second modification example of this embodiment. Fig. 10 is an explanatory view for explaining a malfunction prediction process in an operation example of an apparatus status monitoring device according to a third modification example of this embodiment. -10- Fig. 11 is an explanatory view for explaining a process of estimating a status of a monitoring target apparatus in an operation examph of an apparatus status monitoring device according to a fourth modification example of this embodiment. Fig.72 is an explanatory view for explaining a malfunction prediction process in an operation example of an apparatus status monitoring &vice according to a fifth modification example of this embodiment. Fig. 13 is a view showing an application example in which an apparails status monitoring device according to a sixth modification example of this embodiment is applied to a travel motor for a construction machine. Fig. 14 is a view showing an application example in which the apparatus status monitoring device according to the sixth modification example of this embodiment is applied to an automatic door. Fig. 15 is a view showing an application example in which the apparatus status monitoring device according to the sixth modification example of this embodiment is applied to a wind turbine for wind power generation. Fig. 16 is a view showing an application example in which the apparatus status monitoring device according to the sixth modification example of this embodiment is applied to a heliostat for solar thermal power generation. Fig. L7 is a block diagram showing a detail of an apparatus status &termination unit in an apparatus status monitoring device according to a seventh modification example of this embodiment. Fig. 18 is a flow chart showing an operation example of the apparatus status monitoring device according to the seventh modification examph of this embodiment. Fig. 19 is a flow chart, as a continuation of Fig. 18, showing the operation example of the apparatus status monitoring device according to the seventh modification example of this embodiment. -Lt- Fig. 20 is an explanatory view for explaining a malfunction prediction process based on a combination of a plurality of pieces of physical information in the operation examph of the apparatrs status monitoring device according to the seventh modification example of this embodiment. Fig.2t is an explanatory view for explaining a process of determining a status of a monitoring target apparatus in an operation example of an apparatus status monitoring device according to an eighth examph of this embodiment. Fig.22 is a view showing an operation checking device according to a ninth modification example of this embodiment. Fig. 23 is a block diagram showing a sfructure status monitoring device according to a tenth modification example of this embodiment. DESCRIPTION OF THE PREFERRED EMBODIMENTS [00381 With reference to the appended drawings, the following describes in deail an apparatus status monitoring device as one example of a status checking device for a built-in object according to an embodiment of the present invention. Embodimenb described below are each one examph of an embodiment of the present invention, and the present invention is not intended to be construed as being limited thereto. Furthermore, in the drawings referred to in this embodiment, the same parB or parB having similar functions are denoted by the same or like reference characters, and duplicate descriptions thereof are omitted Furthermore, for the sake of convenience of description, a dimensional ratio of the drawings is possibly different from an actual dimensional ratio, and some ehmenB of a configuration are possibly omitted from the drawings. [00391 Fig. 1 is a block diagram showing an apparatus status monitoring device L -L2- according to this embodiment. The apparatus status monitoring device L according to an example shown in Fig. l- is characterized in that, independently of an industial machine 3 as one examph of an object according to the embodiment of the present invention, the apparatus status monitoring device 1 is capabh of monitoring, ouBide the indusfrial machine 3, an operation strtus of a monitoring target apparatus 2 built in the industrial machine 3, which is unable to be directly checked from ouBide. Herein, the monitoring target apparatus 2 is one examph of a target according to the embodiment of the present invention. As shown in Fig. L, the apparatus status monitoring device f. is provided with an information acquisition unit LL and an apparatus status determination unit 12. [0040] (lnformation Acquisition Unit 11) The information acquisition unit L1 acquires physical information manifested ouBide the indusftial machine 3 including the monitoring target apparatus 2 built therein. [0041] A state of including the monitoring target apparatus 2 built therein refers to both of a case where the monitoring target apparatus 2 is completely housed inside the industrial machine 3 and thus a status of the monitoring target apparatus 2 is unable to be directly checked from outside and a case where, although a part of the monitoring target apparatus 2 is exposed to ouside of the industrial machine 3, a status of the monitoring target apparatus 2 is unable to be directly checked from ouBide. lOO42l Fig.2 is a view showing a group of examples of the industrial machine 3 to which the apparatus status monitoring device L according to this embodiment is applicable. There is no particular limitation on the industrial machine 3 as long as it is a machine used for activities related to industy, i.e. providing producB and services. -13- For example, as shown in Fig. 2,the industrial machine 3 may be an indusfrial robot 30A used for automobih production, a speed reducer 30B built in the industrial robot 30A, a compressor 30C used in an elecffic [ain, a construction machine 30D, a travel motor 30E for a construction machine, or the like. [00431 Fig. 3 is a view showing another group of examples of the indusfrial machine 3 to which the apparatus status monitoring device L according to this embodiment is applicabh. Other than the group of examples shown in Fig. Z, for example, as shown in Fig. 3, the industrial machine 3 may be a filling and packaging machine 30F used for food packaging or the like, an aircraft 30G a flight contol actuator 30H that actuates a movabh wing of an aircraft, an automatic door 301, a speed reducer or a bearing built in a wind turbine 30f for wind power generation, a speed reducer or a bearing built in a heliostat 30K for solar thermal power generation. lOO44l There is no particular limitation on the monitoring target apparatus 2 as bng as it is an apparatus built in the industrial machine 3. The monitoring target apparatus 2 built in the indusffial robot 30A may be, for example, the speed reducer 308, a bearing, or a motor. The monitoring target apparatus 2 built in the speed reducer 30B may be, for example, a Eear, a bearing, or a seal member for lubricant sealing. The monitoring target apparatus 2 built in the compressor 30C may be, for example, an air compression mechanism referred to as an air end The monitoring target apparatus 2 built in a construction machine may be, for example, the travel motor 30E for a construction machine. The monitoring target apparatus 2 built in the travel motor 30E for a constuction machine may be, for example, a planetary gear. The monitoring target apparatus 2 built in the filling and packaging machine 30F may be, for examph, a link apparatus. The monitoring target apparatus 2 built in an aircraft may be, for example, the flight control actuator 30H. The monitoring target apparatus 2 built in -L4- the flight control actuator 30H may be, for example, a valve. The monitoring target apparatus 2 built in the automatic door 301 may be, for example, an ehctric motor. The monitoring target apparatus 2 built in the wind Urrbine 30J for wind power generation may be, for example, a speed reduce4 a speed increase4 a bearing, or a motor. The monitoring target apparatus 2 built in the heliostat 30K for solar thermal power generation may be, for example, a speed reduce4 a bearing, or a motor. [00451 The physical information regarding the industrial machine 3 manifested ouBide the industrial machine 3 is, for exampb, physical information regarding a surface 3a of the industrial machine 3. The physical information regarding the industrial machine 3 refers to information acquirable as a quantified value from the industrial machine 3. The surface 3a of the industial machine 3 refers to a portion of the indusftial machine 3, which is accessible in a contact or non-contact manner from ouBide of the indusffial machine 3. In a case where the surface 3a is transparent, the surface 3a may include a transparent portion and a portion at a back thereof. Furthermore, the surface 3a may include, in addition to the surface 3a of the industial machine 3 iBelf, a surface of a substance provided on the surface 3a of the indusffial machine 3 for the purpose of acquiring physical information, by, for examph, processing the surface 3a, being applied to the surface 3a, or being attached to the surface 3a. [00461 The physical information regarding the surface 3a of the industial machine 3 may be, for example, a temperature, a position, a strain, a displacement, a vibration, a refuctance of a sound wave, ultrasoun{ infrared light, or any other type of light, an ehctromagnetic wave absorption rate, a hue, a brighfiress, a saturation, a moisture amount, or an oil amount. The physical information manifested oubide the industrial machine 3 is not limited to physical information regarding the surface 3a of the -15- industrial machine 3. For example, the physical information manifested ouside the indusftial machine 3 may be a sound or an odor emitted from the industrial machine 3 and detected ouBide the indusffial machine 3. Moreove4 the physical information may be, for example, an intensity of radiation such as X-rays, an ebcffomagnetic wave, ultrasound or the like tansmitted or propagated in the industrial machine 3 and detected ouBide the industial machine 3, or an emission such as an exhaust gas emitted by the industrial machine 3 and detected ouBide the industrial machine 3. 100+71 The information acquisition unit 11 may be a contact-type information acquisition unit L1- that acquires physical information while being in conhct with the surface 3a or a non-contact-type information acquisition unit 11 that acquires physical information while not being in contact with the surface 3a. According to the non-contact-type information acquisition unit 11, since it does not come in contact with the industial machine 3, a status of the monitoring target apparatus 2 can be detected without exerting an adverse effect on an operation of the industial machine 3. [00481 The contact-type information acquisition unit 11 may be, for example, a thermometer that measures a temperature, a potentiometer that measures a position or a displacement, a strain gauge that measures a sffain, a vibrometer that measures a vibration, a moisture sensor that measures a moisture amount, or an oil sensor that measures an oil amount. [0049] The non-contact-type information acquisition unit 11 may be provided with, for example, a radiation thermometer for measuring a temperature, a laser-type or an eddy current-type disance/displacement sensor for measuring a position or a displacement, a laser Doppler-type non-contact vibrometer for measuring a vibration, -L6- a sound wave or ulfrasound detector (including those disposed in two dimensions) that outpub a sound wave or ulffasound and receives a refucted wave thereo{, a camera for measuring a refhctance of infrared light or any other type of light, a hue, a brighUress, or a saturation, a sensor using a microwave or an image to measure a moisture amount, a sensor using a Iaser to measure an oil amount, a microphone that measures a sound, a radiation measuring instrument that measures radiation, an electromagnetic wave measuring instrument that measures an ehctromagnetic wave, an ultrasound measuring instrument that measures ultasound or a gas measuring instrument that measures a gas such as an exhaust gas or a hazardous gas. [0050] The non-contact-type information acquisition unit L1- may be provided with a camera for acquiring physical information based on a captured image of at least a part of the surface 3a of the industrial machine 3. Physical information is acquired based on an image captured by the camera, and thus physical information can be acquired using a simple configuration without exerting an adverse effect on an operation of the industrial machine 3. [0051] The camera may have an enlarged image capturing function of capturing an enlarged image of at least a part of the surface 3a of the industial machine 3, namely, a zoom function. An enlarged image of the surface 3a is captured, and thus a particular piece of physical information regarding the surface 3a can be acquired at a high resolution. [00521 The camera may have an optical system capable of wide-angh or omnidirectional image capturing, such as a fish-eye lens. The camera has such an optical system having a wide angh of view, and thus blind spoS of the camera on the surface 3a of the industrial machine 3 can be reduced -t7 - [00531 A plurality of such cameras may be provided so that images of different areas on the surface 3a of the indusffial machine 3 can be captured The plurality of cameras are provided and thus blind spob of the cameras on the surface 3a of the industrial machine 3 can be further reduced [00541 The camera may be a color CCD or a CMOS camera that captures an image of a hue, a brightress, or a saturation of a pressure-sensitive coating material whose color changes depending on a pressure or a temperature-sensitive coating material that is one example of a thermochromic member whose color changes depending on a temperahrre. Such a CCD or a CMOS camera and a pressure-sensitive coating material or a temperature-sensitive coating material are used, and thus physical information regarding the surface 3a of the industrial machine 3 can be acquired with accuracy, while an adverse effect on the industrial machine 3 is suppressed" [0055] The camera may be a CCD or a CMOS camera (having sensitivity in a visible light region regardless of whether it is of a color-type or a monochrome-type or having sensitivity in an infrared region) that acquires a hue, a brightress, a saturation, or a light reflectance of the surface 3a of the industial machine 3. An amount of moisture or oil adhering to the surface 3a of the industrial machine 3 can be acquired based on a hue, a brightress, a saturation, or a light reflectance, and thus physical information regarding the surface 3a of the industrial machine 3 can be acquired with accuracy, while an adverse effect on the industial machine 3 is suppressed [0056] The camera may be a TOF (time-of-flight) camera. The TOF camera is a distance image sensing camera that can irradiate a subject with pulsed near infrared light, receive reflected light of the near infrared light from the subject with a TOF sensol and measure a distance to the subject based on a required reflection time of -18- the thus received reflected light. According to the T0F camera, a distance to the surface 3a of the industrial machine 3, namely, depth information can be acquired and thus a displacement of the indusftial machine 3 can be measured without using a device that projecb a particular pattern. Moreove4 it is also possible to acquire a vibration as a temporal change in displacement, and to measure a strain as a temporal change rate in displacement (a differentiation value of a displacement). Through the use of the TOF camera, a three-dimensional shape of the surface 3a can be easily acquired with high accuracy. [00571 The non-contact-type information acquisition unit L1 may be composed of a projector that projecB a random pattern, a gird pattern, a dot pattern or the like on the surface 3a of the industrial machine 3, a camera that captures an image of any of these patterns, and a calculator that calculates a sffain of the surface 3a from the thus captured image. In this case, the calculator may calculate a strain based on a degree of temporal deformation of a pattern whose image has been captured The calculator may acquire a three dimensional shape of at least a part of the surface 3a of the industrial machine 3 based on a captured image of a pattern and acquire a strain based on a degree of temporal deformation of the thus acquired three dimensional shape. With a three dimensional shape used as a basis, accuracy in measuring a strain can be improved [00581 The non-contact-type information acquisition unit 11 may be provided with a radar that acquires an electomagnetic wave absorption rate. By measuring a radio wave absorption rate and a change therein, a displacement of the surface 3a of the industial machine 3 can be measured Moreover; it is also possible to acquire a vibration as a temporal change in displacement, and to measure a sfrain as a temporal change rate in displacement (a differentiation value of a displacement). -t9- [00591 The non-contact-type information acquisition unit L1 may be provided with a microphone that acquires a sound A plurality of such microphones may be disposed on at least one of a hteral side and an upper side of the industial machine 3 so as to face the industial machine 3 in a state where the plurality of microphones are spread in a plane shape or a curved surface shape. The plurality of microphones are disposed and thus sounds at different areas on the surface 3a of the industrial machine 3 can be acquired with accuracy. [00601 The non-contact-type information acquisition unit 11 may be provided with an odor sensor that acquires an odor. There is no particular limitation on specific aspecB of the odor sensor. For example, the odor sensor may be a semiconductor-type odor sensor that detecB an amount of odor molecules absorbed to a surface of a semiconductor as an amount of change in resistance value of the semiconductor. Furthermore, the odor sensor may be a quarE crystal resonator-type odor sensor that has a sensitive film attached to a surface of a resonator and detecb an amount of odor molecuhs absorbed to the sensitive film as an amount of decrease in resonance frequency of the resonator due to an increase in mass of the sensitive film. [0061] The non-contact-type information acquisition unit 11 may be provided with a radiation detector that detecB, with a senso4 radiation such as X-rays transmitted through the industrial machine 3 and cahulates an absorption rate of X-rays absorbed by the industial machine 3 based on an amount of the radiation such as X-rays thus detected, or an ultasound detector that detecE, with a sensof,, ultrasound transmitted through the industial machine 3 and cabulates an absorption rate of ultasound absorbed by the industrial machine 3 based on an amount of the ultrasound thus detected -20 - [00621 (Apparatus Satus Determination Unit 12) Fig. 4 is a block diagram showing a deAilof the apparatus status determination unit 12 in the apparatus status monitoring device 1 according to this embodiment, as one example of the status determination unit according to the embodiment of the present invention. As shown in Fig. 4, the apparatus status determination unit 12 has a status estimation unit 121- and a malfunction prediction unit 122. [0063] The status estimation unit 121 estimates a stails of the monitoring target apparatus 2 based on physical information acquired by the information acquisition unit Ll-. MoreoveL the status estimation unit 121- determines whether the thus estimated status of the monitoring target apparatus 2 is a pre&termined state, for examph, an abnormal state. That is, the stahrs estimation unit 121 functions as an abnormality determination unit and determines whether the predetermined state is the abnormal state based on acquired physical information. When it is determined that the estimated status is the abnormal state, the status estimation unit 121 ou@uB, by wire or wirehssly, abnormality occurrence information that gives notification of the abnormal state of the monitoring target apparatus 2 to a server 4 external to the apparatus status monitoring device L. Moreover; the stahrs estimation unit 121- ffansmib the stahrs of the monitoring target apparatus 2 to the malfunction prediction unitIZ2. [00641 The malfunction prediction vnit722 determines whether the estimated status of the monitoring target apparatus 2 is a state where a malfunction is predicted to occur within a predetermined time period When it is determined that the estimated status is the state where a malfunction is predicted to occur within a predetermined time period the malfunction prediction unit 122 outpuB, by wire or wirelessly, malfunction prediction information that gives notification of the predicted -ZL- malfunction to the server 4. When no determination is ma& on whether the estimated status is the abnormal state or the state where a malfunction is predicted to occur within a predetermine time period, the malfunction prediction unit722 outpuB apparatus status information that indicates the estimated status of the monitoring target apparatus 2 to the server 4. [0065] Hereinafter; information acquired by the apparatus status &termination unit 12, such as abnormality occurrence information, malfunction prediction information, and apparatus status information, is referred to also as acquired information by the apparatus status determination unit 12. [00661 The abnormal state or the state where a malfunction is predicted to occur within a predetermined time period of the monitoring target apparatus 2 is not particularly limited as long as they are statuses of the monitoring Arget apparatus 2 that can be estimated based on physical information regarding the industrial machine 3 manifested outside the industrial machine 3. For example, the abnormal state or the state where a malfunction is predicted to occur within a predetermined time period may be a state where a temperature of the monitoring target apparatus 2 is equal to or higher than a preset temperailre. Furthermore, the abnormal state or the state where a malfunction is predicted to occur within a predetermined time period may be a state where the monitoring target apparatus 2 has, in a particular portion thereof, a strain, a displacement, or a change in shape equal to or larger than a preset level of strain, displacement, or change in shape. Furthermore, the abnormal state or the state where a malfunction is predicted to occur within a predetermined time period may be a state where the monitoring target apparatus 2 has, in a particular portion thereof, an amplitude or a cycle of a vibration equal to or larger than a preset value of amplitude or cycle. Furthermore, the abnormal state or the state where a malfunction is -22 - predicted to occur within a predetermined time period may be a state where the monitoring target apparatus 2 has, in a particular portion thereof, an acceleration or a jerk (an accehration change rate per unit time) equal to or larger than or equal to or smaller than a preset value of acceleration or jerk. Furthermore, in a case where the information acquisition unit L1- acquires a plurality of pieces of physical information, the abnormal state or the state where a malfunction is predicted to occur within a predetermined time period may be a state where at least two of a temperature, a strain, a displacement, a vibration, an accehration, and a jerk of the monitoring target apparatus 2 have a preset pre&termined relationship. Furthermore, the abnormal state or the state where a malfunction is predicted to occur within a predetermined time period may be a state where a physical status of a preset plurality of portions of the monitoring target apparatus 2 agrees with a preset state. In these examples of the abnormal state or the state where a malfunction is predicted to occur within a predetermined time period, the term "preset" may signify a fixed state or a state of being variable, based on a predetermined relationship, depending on, for examph, a change in operation time or installation environment of the industial machine 3. As previously mentioned by the status estimation unit 121, these examples of the abnormal state are determined to be a malfunctioning state of the monitoring target apparatus 2. Furthermore, by the malfunction prediction unit1.2Z, these examphs of the state where a malfunction is predicted to occur within a predetermined time period are determined as a malfunction prediction that predicE occurrence of a predetermined malfunction within a predetermined time period [00671 The abnormal state or the state where a malfunction is predicted to occur within a predetermined time period may be affected by a relationship between a position on the surface 3a at which physical information is manifested and a position -23 - of the monitoring target apparatus 2. For examph, even when pieces of physical information having equalvalues are acquired, a result of a determination on whether the monitoring target apparatus 2 is in the abnormal state or the state where a malfunction is predicted to occur within a predetermined time period may vary depending on a distance between a position on the surface 3a at which each of the pieces of physical information is acquired and a position of the monitoring target apparatus 2. Similarly, a result of a determination on whether the monitoring target apparatus 2 is in the abnormal state or the state where a malfunction is predicted to occur within a predetermined time period may vary depending on an external factor of the surface 3a regarding which physical information is acquired and the monitoring target apparatus 2. The external factor refers to a temporary or continual disturbance factor with respect to physical information to be acquired, such as an optical disturbance including sunlight, a radio wave state, a sound state, or a wind [00681 The apparatus status determination unit 12 is, for example, a piece of hardware such as an arithmetic processing unit or a storage device. At least a part of the apparails status determination unit LZ may be a piece of sofhnrare. The apparatus status determination unit 12 may be mounted in one apparatus status monitoring device L or provided on a system (for example, a server or a daabase on a cbud) in which any constituent part thereof (for example, the malfunction prediction unit L22) is communicable with the apparatus status monitoring device 1 through a network. [00691 The server 4 may notiff a user of acquired information by the apparatus status determination unit 12 inputted from the apparatus status determination unit 12 by, for example, displaying it on a display. [00701 (Operation Example) Next, a description is given of an operation example of 24- the apparatus status monitoring device 1. Fig. 5 is a flow chart showing an operation example of the apparatus status monitoring device 1 according to this embodiment. A procedure shown in this flow chart is repeatedly imphmented as required [0071] First, as shown in Fig. 5, the information acquisition unit 11 acquires physical information manifested ouside the industrial machine 3 (step SL). lOO72l After the physical information has been acquired the status estimation unit L2L estimates a status of the monitoring target apparatus 2 based on the thus acquired physical information (step S2). [00731 Next, the status estimation unit 12]. determines whether the thus estimated status of the monitoring target apparatus 2 is the abnormal state (step S3). lOO74l In a case where the estimated status of the monitoring target apparatus 2 is the abnormal state (YES at step S3), the status estimation unit 12L outputs abnormality occurrence information to outside (step S4). [00751 On the other hand in a case where the estimated status of the monitoring target apparatus 2 is not the abnormal state (NO at step S3), the malfunction prediction unit tZZ determines whether the estimated status of the monitoring target apparatus 2 is the state where a malfunction is predicted to occur within a predetermined time period [step S5). [00761 In a case where the estimated status of the monitoring target apparatus 2 is the state where a malfunction is predicted to occur within a pre&termined time period (YES at step S5), the malfunction prediction unitL22 outputs malfunction prediction information to ouBide (step 56). 0n the other hand, in a case where the estimated status of the monitoring target apparatus 2 is not the state where a -25 - malfunction is predicted to occur within a predetermined time period (N0 at step S5), the malfunction prediction unit 122 outpuB a piece of apparatus status information corresponding to the estimated status of the monitoring target apparatus 2 to ouBide [step S7). lOO77l When an attempt is made to provide a sensor and wiring for directly detecting a status of the monitoring target apparatus Z in a limited space inside the indusffial machine 3, due to restrictions on a size, a shape, a power feeding method a data tansmission scheme, and an amount of wiring of the senso4 the sensor and wiring could hardly be provided [00781 As a solution to this, according to the apparatus status monitoring device 1 of this embodiment, a piece of physical information regarding the surface 3a of the industrial machine 3 is acquired, and based on a correspondence relationship between the thus acquired piece of physical information and a status of the monitoring target apparatus 2 built in the industial machine 3, which is set so as to correspond to the thus acquired piece of physical information, a status of the monitoring arget apparatus 2 built in the industrial machine 3 can be estimated The correspondence relationship may be set based on actual measurement or set based on a physical cahulation model By this configuration, without the need to provide a dedicated sensor and wiring for directly detecting a status of the monitoring target apparatus 2 inside the indusffial machine 3, a status of the monitoring target apparatus 2 can be detected [00791 Thus, according to this embodiment, without directly providing a sensor in the monitoring target apparatus 2 built in the industrial machine 3, a status of the monitoring target apparatus Z can be monitored -26- [00801 (First Modification Example) Next, a fuscription is given of a first modification examph in which a result of monitoring by the apparatus strtus monitoring device 1 is used to confol the industial machine 3. Fig. 6 is a block diagram showing an apparatus status monitoring device 1 according to the first modification example of this embodiment. In an example shown in Fig. 1, the apparatus stahrs monitoring device 1 is independent of the industrial machine 3 [0081] In contrast to this, the apparails status monitoring device 1 of the first modification example is characterized in that a result of monitoring the monitoring target apparatus 2 is used to control the industrial machine 3. [0082] Specifically, in the first modification example shown in Fig. 6, an apparatus status determination unit 12 ou@uB acquired information by the apparatus status determination unit '1.2 to an industrial machine conffol device 5 that controls an operation of the industrial machine 3. [0083] The industrial machine contol device 5 controls an operation of the indusffial machine 3 based on the acquired information by the apparatus status determination unit 12 inputted from the apparatus status &termination unit L2.For examph, in a case where the acquired information by the apparahls status &termination unit 12 is malfunction information, the industrial machine control device 5 shuB down the industrial machine 3 in accordance with the malfunction information. Furthermore, in a case where the acquired information by the apparatus status &termination unit 12 is malfunction prediction information, the industial machine contol device 5 may shut down the industrial machine 3 in accordance with the malfunction prediction information or may limit an achration force or a movabb range of the industrial machine 3 in accordance with the malfunction prediction -27 - information. [00841 Also in the first modification examph, without directly providing a sensor in the monitoring target apparails 2 built in the industrial machine 3, a status of the monitoring target apparatus 2 can be monitored Furthermore, an operation of the industial machine 3 can be contolled based on acquired information by the apparatus status determination unit L2, and thus the industrial machine 3 can be prevented from performing a faulty operation or can be kept in an actuated state until maintenance timing. [0085] (Second Modification Example) Next, a description is given of a second modification examph in which a status of a speed reducer 30B built in an industrial robot 30A is monitored Fig.7 is a view showing an application example in which an apparatus status monitoring device 1 according to the second modification example of this embodiment is applied to the industial robot 30A. [00861 As shown in Fig. 7, in the second modification example, the indusffial robot 30A having at least one rotation shafs 306 to 310 represents the industial machine 3. More specifically, the indusftial robot 30A has a mounting portion 300, first to fifth arms 301- to 305, and the first to fifth rotation shafs 306 to 310. [00871 The mounting portion 300 is provided at a predetermined mounting position B such as on a floor; for mounting the indusftial robot 30A. [00BBI The first rotation shaft 306 connecB the mounting portion 300 to one end of the first arm 301-. The first rotation shaft 306 includes a first speed reducer 308-1 built therein, which decelerates rotation of an unshown motor and outpub the rotation, and the roadon thus outputted from the first speed reducer 30B-1 is -28 - ftansmitted to the first rotation shaft 306, causing the first rotation shaft 306 to rotate about an axis direction parallel to aZ direction (namely, a vertical direction) in Fig. 7. [00891 The first arm 30]. extends from the one end thereof connected to the mounting portion 300 toward the other end thereof. The first arm 301 rotates folhwing rotation of the first rotation shaft 306 positioned on a side nearer to the mounting position P than the first arm 30L about the axis direction of the first rotation shaft 306. [00901 A second rotation shaft 307 connecB the other end of the first arm 301 to one end ofa second arm 302. The second rotation shaft 307 includes a second speed reducer 30B-2 built therein, which decelerates rotation of an unshown motor and outpuB the rotation, and the rotation thus outputted from the second speed reducer 308-2 is tansmitted to the second rotation shaft 307, causing the second rotation shaft 307 to rotate about an axis direction orthogonal to the Z direction. While in a state shown in Fig. 7,the axis direction of the second rotation shaft 307 is paralbl to a Y direction, on a side nearer to the mounting position P than the second rotation shaft 307, the axis direction of the second rotation shaft 307 changes with rotation of the first rotation shaft 306 having the axis direction different from that of the second rotation shaft 307. [0091] The second arm 302 extends from the one end thereof connected to the first arm 30L toward the other end thereof. The second arm 302 rotates following rotation of the first and second rotation shaffs 306 and 307 positioned on a side nearer to the mounting position P than the second arm 302 about the axis directions of the first and second rotation shafs 306 and 307. [0092] The third rotation shaft 308 connecB the other end of the second arm 302 -29 - to a one end side of the third arm 303. The third rotation shaft 308 includes a third speed reducer 30B-3 built therein, which decebrates rotation of an unshown motor and outpuB the rotation, and the rotation thus outputted from the third speed reducer 308-3 is transmitted to the third rotation shaft 308, causing the third rotation shaft 308 to rotate about an axis direction paralhl to the axis direction of the second rotation shaft 307. While in the state shown in Fig. 7,the axis direction of the third rotation shaft 308 is parallel to the Y direction, on a side nearer to the mounting position P than the third rotation shaft 308, the axis direction of the third rotation shaft 308 changes with rotation of the first rotation shaft 306 having the axis direction different from that of the third rotation shaft 308. [00931 The third arm 303 extends from the one end side thereof connected to the second arm 302 toward the other end thereof. The third arm 303 rotates following rotation of the first to third rotation shafts 306 to 308 positioned on a side nearer to the mounting position P than the third arm 303 about the axis directions of the first to third rotation shafts 306 to 308. [00941 The fourth rotation shaft 309 connecE the other end of the third arm 303 to one end of the fourth arm 304. The fourth rotation shaft 309 includes a fourth speed reducer 308-4 built therein, which decehrates rotation of an unshown motor and outpuB the rotation, and the rotation thus outputted from the fourth speed reducer 30B-4 is transmitted to the fourth rotation shaft 309, causing the fourth rotation shaft 309 to rotate about an axis direction orthogonal to the axis directions of the first to third rotation shafs 306 to 308. While in the state shown in Fig. 7,the axis direction of the fourth rotation shaft 309 is paralhl to an X direction, on a side nearer to the mounting position P than the fourth rotation shaft 309, the axis direction of the fourth rotation shaft 309 changes with rotation of the first to third rotation shafts 306 to 308 -30- having the axis directions different from that of the fourth rotation shaft 309. [00951 The fourth arm 304 extends from the one end thereof connected to the third arm 303 toward the other end thereof. The fourth arm 304 rotates following rotation of the first to fourth rotation shafs 306 to 309 positioned on a side nearer to the mounting position P than the fourth arm 304 about the axis directions of the first to fourth rotation shafs 306 to 309. [0096] The fifth rotation shaft 310 connecB the other end of the fourth arm 304 to one end of the fifth arm 305. The fifth roation shaft 31-0 inclu&s a fifth speed reducer 308-5 built therein, which decehrates rotation of an unshown motor and outputs the rotation, and the rotation thus outputted from the fifth speed reducer 30B-5 is transmitted to the fifth rotation shaft 310, causing the fifth rotation shaft 310 to rotate about an axis direction parallel to the second rotation shaft 307. While in the state shown in Fig. 7 , the axis direction of the fifth rotation shaft 310 is parallel to the Y direction, on a side nearer to the mounting position P than the fifth rotation shaft 310, the axis direction of the fifth rotation shaft 310 changes with rotation of the first and fourth rotation shafts 306 and 309 having the axis directions different from that of the fifth rotation shaft 310. [0097] The fifth arm 305 extends from the one end thereof connected to the fourth arm 304 toward the other end thereof. The fifth arm 305 rotates following rotation of the first to fifth rotation shafs 306 to 310 positioned on a si& nearer to the mounting position P than the fifth arm 305 about the axis directions of the first to fifth rotation shafts 306 to 310. [00981 As shown in Fig. 7, in the second modification examph, on a surface 3a of the industial robot 30A, specifically, on each of respective surfaces of the first and -31- fourth rotation shafs 306 and 309, there is provided a temperature-sensitive coating film 6 as one example of a thermochromic member whose color changes depending on a temperature. The temperature-sensitive coating film 6 is a film formed by applying a temperature-sensitive coating material on a surface of the industrial machine 3. The temperature-sensitive coating film 6 may be provided also on each of respective surfaces of the rotation shafs 307,308, and 310 other than the respective surfaces of the first rotation shaft 306 and the fourth rotation shaft 309, and on the surface 3a of the industrial robot 30A other than the respective surfaces of the rotation shafts. [00991 As shown in Fig. 7, an information acquisition unit 1-]. of the second modification example has a plurality of cameras 1L0 that capture images of the temperature-sensitive coating films 6 provided on the surface 3a of the industrial robot 30A. Furthermore, the information acquisition unit 11 of the second modification example has a control device 120 that acquires a temperature of each of the respective surfaces of the rotation shafo 306 and 309 based on an image captured by a corresponding one of the cameras 1 10, namely, coloration of the temperaturesensitive coating film 6 that changes depending on a temperature. According to the information acquisition unit 11 of the second modification example, with a captured image of the temperahrre-sensitive coating film 6 provided directly on the surface 3a of the industrial robot 30A used as a basis, a temperature of the surface 3a of the industrial robot 30A can be detected with accuracy. [01001 The plurality of cameras ].10 are disposed away from the surface 3a of the industrial robot 30A so as to surround the industrial robot 30A from a lateral side and an upper side. The cameras 1L0 are disposed so as to surround the industrial robot 30A, and thus blind spoB of the cameras 110 on the temperature-sensitive coating films 6, namely, the surface 3a of the industrial robot 30A can be reduced -32 - [01011 As shown in Fig. 7 ,the apparatus status monitoring device 1 of the second modification example is provided with a drive unit 7 that drives each of the cameras 110 to change an image capturing range. The drive unit 7 may have an actuator such as a motor that causes each of the cameras 110 to rotate so that an orientation of an optical axis thereof is displaced An operation of the drive unit 7 may be controlled by the control device 120. For example, in a case where the temperature-sensitive coating film 6 is displaced as the industial robot 30A moves, the drive unit 7 may drive the cameras 110 to move following a displacement of the temperature-sensitive coating film 6 so that an image of the temperature-sensitive coating film 6 can be captured in a continuous manner. [01021 The control device ].20 functions also as an apparatus status determination unit L2 (namely, a status estimation unit 121- and a malfunction predictionunitL22) of the second examph. Based on a temperature of the surface 3a of the industrial robot 30A acquired from a captured image of the temperature-sensitive coating film 6, the control device 120 determines whether the speed reducer 30B built in the industial robot 30A is in a predetermined state, for example, an abnormal state or a state where a malfunction is predicted to occur within a predetermined time period [01031 In the example shown in Fig. 7, based on a temperature of the surface of the first rotation shaft 306, the control device 120 determines whether the first speed reducer 308-1 built in the first rotation shaft 306 is in the predetermined state. Furthermore, based on a temperahrre of the surface of the fourth rotation shaft 309, the control device L20 determines whether the fourth speed reducer 30B-4 built in the fourth rotation shaft 309 is in the predetermined state. [0104] (Operation Example) Next, a description is given of an operation example of -33- the apparatus status monitoring device 1 of the second modification example. Fig. 8 is a flow chart showing the operation examph of the apparatus status monitoring device L according to the second modification example. During an operation of the industrial robot 30A, the apparatus status monitoring device 1 continually performs processing shown in the flow chart of Fig. B. A procedure shown in this flow chart is repeatedly implemented as required [01051 As shown in Fig. 8, in the second modification examph, step 51-1and step S12 are implemented as the process of acquiring physical information regarding the surface 3a of the indusfial machine 3 described with reference to Fig. 5 fstep S1). Specifically, first, each of the cameras 110 acquires a captured image of the temperature-sensitive coating film 6 provided on the surface 3a of the indusfial robot 30A (step S11). After the caphrred image of the temperature-sensitive coating film 6 has been acquired, based on the thus acquired captured image of the temperaturesensitive coating film 6, the control device 120 measures a temperature distibution on the surface 3a of the industrial robot 30A (step S12). [0106] Next, a status of a speed reducer corresponding to a position of the temperature-sensitive coating film 6, which is indicated by the thus measured temperature distribution, is estimated fstep S21). After the status of the speed reducer has been estimated, the control device 120 determines whether the thus estimated status of the speed reducer is the abnormal state fstep S3). That is, based on a result of a comparison between a temperature at a predetermined position on the surface 3a of the industrial robot 30A and a determination threshold value (an abnormality determination threshold value) for determining presence or absence of the abnormal state, the control device l-20 determines whether the speed reducer corresponding to the predetermined position is in the abnormal state. Specifically, the control device -34- 120 determines whether a temperature of the surfaces of the first rotation shaft 306 and the fourth rotation shaft 309, on each of which the temperature-sensitive coating film 6 is provided, has excee&d a predetermined threshold value. [01071 Herein, the abnormal state refers to, for example, a malfunction state of the first speed reducer 30B-1 built in the first rotation shaft 306 or the fourth speed reducer 30B-4 built in the fourth rotation shaft 309. [01081 The abnormality determination threshold value varies depending not only on a temperature but also on various pieces of physical information acquired by the information acquisition unit 11. Furthermore, a "state where physical information has exceeded the abnormality determination threshold value" as one example of a criterion for an abnormal state determination includes both of the following cases: a case where a value of physical information ibelf exceeds the abnormality determination threshold value, such as the previously mentioned temperature, and a case where a value calculated from physical information for an abnormality determination exceeds the abnormality determination threshold value (the same applies hereinafter). [0109] In a case where the estimated status of the speed reducer is the abnormal sAte (YES at step S3), the conffol device 120 outpuB abnormality occurrence information to ouBide (step 54). [0110] On the other hand, in a case where the estimated status of the speed reducer is not the abnormal state (NO at step S3), the contol device L20 determines whether the estimated satus of the speed reducer is the state where a malfunction is predicted to occur within a predetermined time period (step S5). -35- [01111 Fig, 9 is an explanatory view for explaining a malfunction prediction process in the operation example of the apparatus status monitoring device L according to the second modification example of this embodiment. For example, as shown in Fig. 9, based on a result of a comparison between a temperature at a predetermined position on the surface 3a of the indusffial robot 30A and a malfunction prediction determination threshold value, the control device L20 determines whether there is established the state where a malfunction is predicted to occur within a predetermined time period (step S5). In this case, when a temperature at the predetermined position on the surface 3a of the industrial robot 30A has exceeded the malfunction prediction determination threshold value, the control device LZl may determine that there is established the state where a malfunction is predicted to occur within a predetermined time period 10fl21 Specifically, in an example shown in Fig. 9, the control device 120 compares a time-dependent change in temperature at a predetermined position on an industrial robot surface with a malfuncflon temperature (the malfunction prediction determination threshold value) at which a malfunction of a speed reducer related to the predetermined position occurs. There is no particular limitation on a specific method for acquiring a time-depen&nt change in temperature, and as the method, there can be used, for example, a regression analysis based on temperature values that have been acquired up to a current determination time t2. While in the example shown in Fig. 9, a time-dependent change in temperature is acquired as a linear function of time, it may also be acquired as a function other than a linear function. In comparing a time-dependent change in temperature with the malfunction temperature, the control device L20 calculates, based on the time-dependent change in temperature, a length of time between a time t3 at which a temperature of the -36- industrial robot surface is predicted to reach the malfunction temperature and the current determination time t2 as the predetermined time period That is, in a case where a time-depen&nt change in temperature exceeds the malfunction temperature in a time range from the current determination time t2 to the time t3 after a lapse of the pre&termined time period therefrom, the control device L20 determines that the speed reducer is in the state where a malfunction is predicted to occur within a predetermined time period [01131 The malfunction prediction determination threshold value varies depending not only on a temperature but also on various pieces of physical information acquired by the information acquisition unit 11. Furthermore, a "state where physical information has exceeded the malfunction prediction determination threshold value" as one examph of a criterion for a malfunction prediction determination includes both of the following cases: a case where a value of physical information iBelf exceeds the malfunction prediction determination threshoH value, such as the previously mentioned temperature cahuhted from a temperature of the surface 3a of the industial robot 30A, and a case where a value cahulated from physical information for a malfunction prediction determination exceeds the malfunction prediction determination threshold value (the same applies hereinafter). [01141 In a case where the estimated status of the speed reducer is the state where a malfunction is predicted to occur within a predetermined time period (YES at step S5), the control device 120 outpuB malfunction prediction information to ouBide (step s6). [0115] On the other hand, in a case where the estimated status of the speed reducer is not the state where a malfunction is predicted to occur within a predetermined time -37 - period [No at step S5), the contol device 120 outpuB a piece of apparatus status information regarding the speed reducers 30B-1 and 30B-4 corresponding to the estimated status of the speed reducer to oubide (step 571). [01161 According to the second modification example, the temperature-sensitive coating film 6 is provided on the surface of each of the rotation shaffs 306 and 309 closest to the speed reducers 30B-1 and 308-4, respectively, and based on a captured image of the temperature-sensitive coating film 6, a temperature of the surface of each of the rotation shaffs 306 and 309 is acquired Thus, based on a temperature, a status of each of the speed reducers 30B-1 and 308-4 can be grasped without directly providing a sensor in the each ofthe reducers 30B-1 and 308-4. lOLLTl (Third Modification Example) Next, a description is given of a third modification example in which pre-acquired information regarding a time-dependent change in physical information at a time of a malfunction is used to perform a malfunction prediction. Fig. L0 is an explanatory view for explaining a malfunction prediction process in an operation example of an apparatus status monitoring device 1 according to the third modification example of this embodiment. [0118I With reference to Fig. 9 showing the second modification examph, there has been described an example in which a malfunction prediction determination is performed based on whether a temperature of the industrial robot surface exceeds the malfunction temperature. [01191 In contast to this, in the third modification example, as shown in Fig. 10, the control &vice 120 compares a time-&pendent change in temperature of an industrial robot surface [hereinafter; referred to also as acquired time-dependent information) with a pre-acquired time-dependent change in temperahrre of the industrial robot -38- surface at a time of a malfunction (hereinafte[ referred to a]so as a malfunction-time time-dependent information) and cahulates a degree of agreement between these pieces of time-dependent information. Then, in a case where the thus cahulated degree of agreement has exceeded a malfunction prediction determination threshold value, the contol device L20 determines that an estimated status of a speed reducer is the state where a malfunction is predicted to occur within a predetermined time period [01201 More specifically, the malfunction-time time-dependent information is information pre-acquired through an experiment or a simulation and has, as shown in Fig. 10, a piece of information at the malfunction time t2 of the speed reducer relative to a startup time of the industrial machine 3 as a starting point. After a startup of the industrial machine 3, at a determination time t1- a pre&termined time period earlier than the malfunction time t2, the control device 120 cahulates a degree of agreement between the acquired time-dependent information and the malfunction-time timedependent information and performs a determination based on a comparison between the thus cahulated &gree of agreement and the malfunction prediction determination threshoH value. l0t?tl There is no particular limitation on specific aspects of the degree of agreement between the acquired time-dependent information and the malfunctiontime time-dependent information as long as the degree has a value increasing with decreasing difference between a piece of the acquired time-dependent information that has been acquired up to the determination time tL and a corresponding piece of the malfunction-time time-dependent information (namely, a temperature difference). For examph, the degree of agreement may have a value proportionate to a reciprocal of an average value of a difference between a piece of the acquired time-dependent -39- information that has been acquired up to the determination time tL and a corresponding piece of the malfunction-time time-dependent information. l0L?zl According to the third modification example, a comparison is made between the acquired time-dependent information and the malfunction-time time-dependent information, and thus a malfunction can be predicted without providing a sensor in a speed reducer and even in a case where a malfunction cannot be predicted simply by using a linear function or any other function. [0123] (Fourth Modification Example) Next, a description is given of a fourth modification example in which a status of the monitoring target apparatrrs 2 is estimated based on a comparison with a piece of physical information pre-acquired when the monitoring target apparatus 2 is in a predetermined state (not necessarily the malfunction state). Fig. L1 is an explanatory view for explaining a process of estimating a status of the monitoring target apparatus 2 in an operation example of an apparatus strtus monitoring &vice 1 according to the fourth modification example of this embodiment. lOL?4l As shown in Fig. 11, in the fourth modification example, an apparatus status determination unit 12 has pre-acquired a first piece of physical information acquired when the monitoring target apparatus 2 is in the predetermined state fnot necessarily the malfunction state). In an example shown in Fig. LL, the first piece of physical information is a piece of time-dependent information indicating a change over time in physical information. The time-dependent information may be acquired through, for example, an experiment or a simulation that has been performed beforehand Furthermore, the time-dependent information may vary depending on a condition such as a use environment or a time period of use of the industrial robot 30A. -40- [01251 The apparatus status determination unit 12 compares a second piece of physical information acquired by an information acquisition unit 11 with the first piece of physical information. Then, in a case where the second piece of physical information agrees with the first piece of physical information, the apparatus status determination unit 12 determines that the monitoring target apparatus 2 is in the predetermined state (not necessarily the malfunction state). The agreement mentioned here is not limited to an exact agreement and may include a case where an error of the second piece of physical information with respect to the first piece of physical information is not more than a threshoH value (namely, a case where the degree of agreement exceeds a threshoH value). On the other hand, in a case where the second piece of physical information does not agree with the first piece of physical information, the apparatus status &termination unit 12 determines that the monitoring target apparatus 2 is not in the predetermined state. 10126l According to the fourth modification examph, a second piece of physical information acquired by the information acquisition unit 11 is compared with a known first piece of physical information acquired when the monitoring target apparatus 2 is in a predetermined state (not necessarily the malfunction state), and thus it can be easily estimated whether the monitoring target apparatus 2 is in the predetermined state (not necessarily the malfunction state). lD1.27l (Fifth Modification Examph) Next, a description is given of a fifth modification examph in which a cahulation model for a malfunction prediction is generated from a maintenance history of the indusfrial machine 3 in the past and a status history, a malfunction history, and a maintenance history of the monitoring target apparatus 2 in the past, and the malfunction prediction is performed based on this cabulation model Fig.12 is an explanatory view for explaining a malfunction -4L- prediction process in an operation examph of an apparatus status monitoring device L according to the fifth modification examph of this embodiment. [0128I Based on a status determination modelgenerated from history information that is a result of determining a status of a built-in object based on acquired physical information, a malfunction prediction unitt22 determines whether there is established the state where a malfunction is predicted to occur within a predetermined time period l0l29l Specifically, the malfunction prediction unit1-2Z has a history Mabase7223 storing a maintenance history of the industrial machine 3 that is history information including at least timing at which maintenance of the industial machine 3 was performed, a status history of the monitoring target apparatus 2 retaining, as history information, at least a status of the monitoring target apparahrs 2 together with timing at which the statrs was established a malfunction history of the monitoring target apparatus 2 that is history information including at hast timing at which a malfunction occurred in the monitoring target apparatus 2, and a maintenance history of the monitoring target apparatus 2 that is history information including at least timing at which maintenance of the monitoring target apparatus 2 was performed [01301 When the history database L223has all of these histories, a malfunction prediction can be performed with higher accuracy. The history database L223, howeve[ is not necessarily required to retain all of these histories and is only required to have at least any one of these histories. Furthermore, the longer a time period in which the histories are retaine{ the higher accuracy in malfunction prediction can be achieved This time period, howeve4 couH be set as appropriate -42- based on a relationship with a product lifetime of the monitoring target apparatus 2, a relationship with a frequency of occurrence of a malfunction in the monitoring target apparatus 2, or a capacity of a storage unit (not shown) that stores the history database L223. [01311 In this modification examph, the storage unit and a status estimaflon unit l22l that estimates a status of the monitoring target apparatus 2 are provided so as to be physically integral with each other. Howeve[ when, as the storage unit, an external storage unit such as a server on a cloud or the like is used via a communication line such as the Internet, the issue of storage capacity is practically resolved [01321 Moreove4 the malfunction prediction unit1.22 has a model generation unit L224 that generates a cahulation model for a malfunction prediction from the various types of histories stored in the history daabase L223. The model generation unit L224 generates a cabulation model for a malfunction prediction by using, for example, a known modeling technique so that the cabulation model is most suited for temporal changes stored in the status history of the monitoring target apparatus 2 and the malfunction history of the monitoring target apparatus 2, respectively. [01331 At this time, by the model generation unit7224, two or more cahulation models for a malfunction prediction may be provided For examph, there may be provided a normal state model generation unit 7224L that generates a normal state cabulation model by using, among pieces of the status history of the monitoring target apparatus 2, a piece of history information indicating that a malfunction has not occurred within a predetermined time period, and a malfunction state model generation unitLZZ42 that generates a malfunction state calculation model by using, -43- among pieces of the stahJs history of the monitoring target apparatus 2, a piece of history information indicating that a malfunction has occurred within the pre&termined time period Based on reliability in determining whether a normal state or a malfunction state is established, a plurality, such as three or more, of calculation models may be provided By this configuration, a determination can be performed with higher reliability. [01341 For examph, when a status of the monitoring target apparatus 2 inputted from the status estimation unitT?ZL is analogous more to the malfunction state model than to the normal state mo&L the malfunction prediction unit L22 determines that there is established the state where a malfunction is predicted to occur within a predetermined time period [01351 In this modification examph, the model generation unitL224 is provided so as to be physically integral with a malfunction prediction arithmetic unit 1222 and so on. There is, however; no limitation thereto, and a calculation model may be generated on, for example, a server on a cloud or the like via a communication line such as the Internet. In this case, compared with a case of using an incorporated apparahrs, there are advantages such as that a cahulation speed is relatively increased and that a model generation algorithm can be more easily changed ex-post facto. [01361 The calculation model generated bythe model generation unitt224 is sent to the malfunction &tection arithmetic unitL222. Then, estimated information that is information estimated by the status estimation unitl22L is inputted to said model and based on an arithmetic result thereof, a malfunction prediction is performed [0137] At this time, when a plurality of cahulation models are present, a common piece of information estimated by the status estimation unit l22l is inputted to each -44- of the plurality of calculation models, and based on arithmetic resulB thereol a malfunction prediction is performed by using a preset evaluation criterion. [0138] In this modification example, the malfunction prediction arithmetic unit L222, the status estimation unitt22l and so on are provided so as to be physically integral with each other. There is, however; no limitation thereto, and an arithmetic operation may be performed on, for examph, a server on a cloud or the like via a communication line such as the Internet. In this case, compared with a case of using an incorporated apparatus, there are provided advantages such as that a cahulation speed is relatively increased and that a preset evaluation criterion can be more easily changed ex-post facto. [01391 [Sixth Modification Example) Next, a description is given of, as a sixth modification example, application examphs in which the apparatus status monitoring device 1 is applied to any other type of industrial machine 3 than the industrial robot 30A. Fig. 13 is a view showing an application example in which an apparatus status monitoring device 1 according to the sixth modification examph of this embodiment is applied to the travel motor 30E for a consEuction machine. Fig. 14 is a view showing an application example in which the apparatus status monitoring device 1 according to the sixth modification examph of this embodiment is applied to the automatic door 301. [01401 In the examph shown in Fig. 13, based on a captured image of the travel motor 30E for a construction machine captured by a camera 1L0 insalled in the construction machine 30D, an information acquisition unit 11 (not shown) of the apparatus status monitoring device 1 acquires physical information (for example, a stain or a vibration of a surface of the tavel motor 30E for a construction machine) -45- manifested outside the ffavel motor 30E for a constuction machine. Then, based on the thus acquired physical information, an apparatus status determination unit LZ of the apparatus status monitoring &vice 1 performs a determination of a status of the monitoring target apparatus 2 (for example, a planetary gear) built in the ffavel motor 30E for a construction machine. [01411 In the example shown in Fig. 14, based on a captured image of a transom portion of the automatic door 301 captured by a camera 110 insAlled in a vicinity of the automatic door 301 (for example, on a ceiling), the information acquisition unit 11 (not shown) of the apparatus status monitoring device 1 acquires physical information (for example, a temperailre manifested as coloration of the temperaturesensitive coating film 6) regarding a surface of the transom portion of the automatic door 301. Then, based on the thus acquired physical information, the apparatus status determination unit 12 of the apparatus status monitoring device 1 performs a determination (for examph, an abnormality determination or a malfunction prediction &termination) of a stails of an electic motor 3011 built in the transom portion. lDt4?l In an example shown in Fig. 15, based on a captured image of a nacelh of the wind turbine 30f for wind power generation captured by an unmanned aerial vehicle DR (a drone) that is equipped with a camera LL0 and flies in a vicinity of the wind turbine 30f, the information acquisition unit 11 (not shown) of the apparatus status monitoring device 1 acquires physical information (for example, a temperature manifested as coloration of the temperature-sensitive coating film 6) regarding a surface of the nacelle of the wind turbine 30f. Then, based on the thus acquired physical information, the apparatus status determination unit 12 of the apparatus status monitoring device L performs a determination (for example, an abnormality determination or a malfunction prediction determination) of a status of a speed -46- increaser 30f 1 or a drive motor 3012 built inside the nacelle [0143] In an example shown in Fig. L6, based on a captured image of a drive device of the heliostat 30K for solar thermal power generation captured by an unmanned traveling vehich DR (a drone) that is equipped with a camera 110 and flies in a vicinity of the heliostat 30K, the information acquisition unit L 1 (not shown) of the apparatus status monitoring device L acquires physical information (for example, a temperature manifested as coloration of the temperature-sensitive coating film 6) regarding a surface of the drive device of the heliostat 30K. Then, based on the thus acquired physical information, the apparahrs status determination unit 12 of the apparatus status monitoring device L performs a &termination (for examph, an abnormality determination or a malfunction prediction determination) of a status of a speed reducer 30K1- or an ehctronic motor 30KZ that drives the speed reducer 30K1. l0f44l According to the sixth modification examph, the apparahrs status monitoring device 1 is applied to various types of industrial machines 3 and thus can be improved in versatility. [0145] (Seventh Modification Examph) Next, a description is given of a seventh modification example in which a status of the monitoring target apparatus 2 is determined based on a plurality of pieces of physical information. [01461 Fig. L7 is a block diagram showing a detail of an apparatus stahrs determination unit 72 in an apparatus status monitoring device L according to the seventh modification example of this embodiment. As shown in Fig. L7,in the seventh modification examph, an information acquisition unit 1L is capabh of acquiring a plurality of pieces #L to #n (n is a nahrral number equal to or larger than 2, the same applies hereinafter) of physical information regarding the industial machine 3 -47- manifested ouBide the industrial machine 3. There is no particular limitation on specific aspecb of the plurality of pieces #1 to #n of physical information. For example, the plurality of pieces #L to #n of physical information may be a combination of two or more selected from a temperature, a position, a strain, a displacement, a vibration, a refuctance of a sound wave, ulffasound, infrared light, or any other type of light, an electromagnetic wave absorption rate, a hue, a brightress, a saturation, a moisture amount, an oil amount, a sound, an odo[ an intensity of radiation such as X-rays, an elecffomagnetic wave, or ultrasound, and an emission such as an exhaust gas. Specific aspecB of the information acquisition unit 11 for acquiring these types of physical information have already been described by way of examples. lOL47l fStatus Estimation Unit 121) In a case where the plurality of pieces #]. to #n of physical information have been acquired based on the thus acquired plurality of pieces #L to #n of physical information, a status estimation unit l-21 estimates a status of the monitoring target apparatus 2. MoreoveC the status estimation unit 12L determines whether the thus estimated status of the monitoring target apparatus 2 is a predetermined state, for examph, the abnormal state or the state where a malfunction is predicted to occur within a predetermined time period [01481 Based on a result of a comparison between the acquired plurality of pieces #1 to #n of physical information and abnormality determination threshold values (hereinafter; each referred to also as an individual abnormality determination threshold value) corresponding respectively thereto, the status estimation unit L21 determines whether the status of the monitoring target apparatus 2 is the abnormal state. Furthermore, based on a result of a comparison between a combination of the acquired plurality of pieces #1 to #n of physical information and a corresponding set of abnormality determination threshoH values, the status estimation unit 121 -48- determines whether the status of the monitoring target apparatus 2 is the abnormal state. [01491 The individual abnormality determination threshoH value is a threshold value that enables a determination on whether a status of the monitoring target apparatus 2 is the abnormal state based on individual values of the plurality of pieces #1 to #n of physical information. The individual abnormality determination threshold value is, for examph, a value higher than a predetermined threshold value of physical information. When at hast one of the plurality of pieces #1 to #n of physical information has exceeded a corresponding one of the individual abnormality determination threshoh values, the status estimation unit 121 may determine that the status of the monitoring target apparatus 2 is the abnormal state. [01501 The set of abnormality determination threshoH values is a set of threshoH values that enabbs a determination on whether a status of the monitoring target apparahrs 2 is the abnormal state based on the combination of the plurality of pieces #1 to #n of physical information. The set of abnormality determination threshoH values may be, for example, a combination of threshold values lower than the individual abnormality determination threshold values related respectively to the plurality of pieces #1 to #n of physical information. Furthermore, the number of threshold values constituting the set of abnormality determination threshold values may be lower than the number of measured pieces of physical information and may be even one. [01511 In a case where an abnormality determination based on the individual abnormality determination threshold value has determined that the abnormal state is not established, the status estimation unit 121 may perform an abnormality -49- determination based on the set of abnormality determination threshold values. Furthermore, depending on a status of the monitoring target apparatus 2, in place of an abnormality determination based on the individual abnormality determination threshold value, an abnormality determination based on the set of abnormality determination threshold values may be performed For examph, when a status of the monitoring target apparatus 2 is not suited for an abnormality determination using the individual abnormality determination threshold value as in a case of a correlation esablished between the previously mentioned plurality of pieces #l- to #n of physical information, an abnormality determination may be performed based only on the set of abnormality &termination threshold values. [01521 There are cases where in an individual determination with respect to each of the pieces #1 to #n of physical information, the individual abnormality determination threshold value is not exceeded and thus it cannot be determined that the abnormal state is esablished, while in an overall determination with respect to the combination of the plurality of pieces #1 to #n of physical information, it should be determined that the abnormal state is established For example, there are cases where when all of the plurality of pieces #l- to #n of physical information have a value not exceeding but approximating the individual abnormality determination threshold value, taken as a whoh, it should be determined that the abnormal state is established Furthermore, depending on a status of the monitoring target apparatus 2, there are cases where an abnormality determination based on an overall determination with respect to the combination of the pieces #1to #n of physical information is more suited as a technique for determining the stahrs of the monitoring target apparatus 2 than an abnormality determination based on an individual determination with respect to the pieces #1 to #n of physical information. According to the seventh modification -50- example, an abnormality determination is performed based on both of the individual abnormality determination threshold value and the set of abnormality determination threshold values, and thus the abnormal state can be properly detected [01531 When it is determined that a state of the monitoring target apparatus 2 is the abnormal state, the status estimation unit 121 outpuB abnormality occurrence information to the external server 4. [01541 (Malfunction Prediction Unit 122) Based on a result of a comparison between the acquired plurality of pieces #1to #n of physical information and malfunction prediction determination threshold values fhereinafte[ each referred to also as an individual prediction determination threshold value) corresponding respectively thereto, a malfunction prediction unit L22 determines whether a status of the monitoring target apparatus 2 is the state where a malfunction is predicted to occur within a predetermined time period Furthermore, based on a result of a comparison between a combination of the acquired plurality of pieces #1to #n of physical information and a corresponding set of malfunction prediction determination threshold values, the malfunction prediction vnit t22 determines whether the status of the monitoring target apparatus 2 is the state where a malfunction is predicted to occur within a predetermined time period [01551 The individual prediction determination threshoH value is a threshold value that enables a determination on whether a status of the monitoring target apparatus 2 is the state where a malfunction is predicted to occur within a predetermined time period based on individual values of the plurality of pieces #1 to #n of physical information. The individual prediction determination threshold value may be, for example, the malfunction temperature described in the example shown in Fig. 9 or a -51- threshold value of the degree of agreement of time-dependent information described in the example shown in Fig. 10. When it is determined that at hast one of the pieces #1to #n of physical information exceeds the individual prediction determination threshold value based on a comparison with the individual prediction determination threshold value, the malfunction prediction unitL22 may determine that the status of the monitoring target apparatus 2 is the state where a malfunction is predicted to occur within a predetermined time period [01561 The set of malfunction prediction determination threshoH values is a set of threshold values that enables a determination on whether a status of the monitoring target apparatus 2 is the state where a malfunction is predicted to occur within a predetermined time period based on the combination of the plurality of pieces #1 to #n of physical information. The set of malfunction prediction determination threshold values may be, for example, a combination of threshold values lower than the individual prediction determination threshold values corresponding respectively to the plurality of pieces #1 to #n of physical information. Furthermore, depending on a status of the monitoring target apparatus 2,the number of threshold values constituting the set of malfunction prediction determination threshoH values may be lower than the number of pieces of physical information and may be even one. [01571 In a case where a malfunction prediction determination based on the individual prediction determination threshoH value has determined that there is not established the state where a malfunction is predicted to occur within a predetermined time period the malfunction prediction tnit1.22 may perform a malfunction prediction determination based on the set of malfunction prediction determination threshold values. Furthermore, in a case where the status estimation unit 121 has determined that the abnormal state is not established, the malfunction -52- prediction unit L22 may perform a malfunction prediction determination. Furthermore, depending on a status of the monitoring target apparatus 2, in place of a malfunction prediction determination based on the individual prediction determination threshold value, a malfunction prediction determination based on the set of malfunction prediction determination threshold values may be performed [01581 There are cases where in an individual &termination with respect to each of the plurality of pieces #1 to #n of physical information, the individual prediction determination threshold value is not exceeded, and thus a malfunction is not &tecte{ while in an overall determination with respect to the combination of the plurality of pieces #L to #n of physical information, it can be determined that there is a sign of occurrence of a malfunction. Furthermore, depending on a status of the monitoring target apparatus 2, there are cases where a malfunction prediction determination based on an overall &termination with respect to the combination of the pieces #1 to #n of physical information is more suited as a technique for determining the status of the monitoring target apparatus 2 than a malfunction prediction determination based on an individual determination with respect to the pieces #1 to #n of physical information. According to the seventh modification example, with both of the individual prediction determination threshoH and the set of malfunction prediction determination threshold values used as a basis, future occurrence of a malfunction can be properly predicted [01591 (Operation Example) Next, a description is given of an operation example of the apparatus status monitoring device L according to the seventh modification example. Fig. 18 is a flow chart showing the operation example of the apparatus status monitoring device l- according to the seventh modification example of this embodiment. -53- [0160] As shown in Fig. 18, first, the information acquisition unit 11 acquires physical information manifested outside the indusffial machine 3 (step S1). After the physical information has been acquired, the information acquisition unit 1L determines whether the acquired physical information is composed of only one piece fnamely, one type) of physical information (step S8). [01611 In a case where the acquired physical information is composed of only one piece of physical information (YES at step S8), the information acquisition unit 11 estimates a status of the monitoring target apparatus 2 based on the acquired physical information (step S20 1). l0L62l Next, the status estimation unit 121 determines whether the physical information has exceeded the abnormality determination threshold value (step S31). [01631 In a case where the abnormality &termination thresho]d value has been exceeded IYES at step 531), the status estimation unit 121 determines that the status of the monitoring target apparatus 2 is the abnormal state and outputs abnormality occurrence information to ouBi& (step S4). 0n the other hand, in a case where the abnormality determination threshold value has not been exceeded INO at step 531), the status estimation unit 121 &termines that the status of the monitoring target apparatus 2 is not the abnormal state. [01641 In a case where the status of the monitoring target apparatus 2 is not the abnormal state, the malfunction prediction unit 722 &termines whether the physical information has exceeded the malfunction prediction determination threshold value [step 551). [01651 In a case where the malfunction prediction determination threshold value -54- has been exceeded (YES at step S5L), the malfunction prediction unlt1,22 determines that the status of the monitoring target apparatus 2 is the state where a malfunction is predicted to occur within a predetermined time period (that is, a malfunction has been predictedJ and outpuB malfunction prediction information to ouBide (step S6). [0166] 0n the other hand, in a case where the malfunction prediction determination threshold value has not been exceeded (NO at step 551), the malfunction prediction unitl22 ou@uts a piece of apparatus stahrs information corresponding to the estimated status to ouBide (step S7). IOL67[ Fig. 19 is a flow chart, as a continuation of Fig. 18, showing the operation examph of the apparatus status monitoring device 1 according to the seventh modification example of this embodiment. [01681 In a case where the number of pieces of physical information constituting the acquired physical information is not only one (NO at step SB in Fig. 18), the information acquisition unit 11 estimates the status of the monitoring target apparatus 2 based on the acquired plurality of pieces of physical information (step s203). [0169] Next, the status estimation unit 121 determines whether at least one of the plurality of pieces #l- to #n of physical information has exceeded the individual abnormality determination threshold value (step S32). [0170] In a case where the individual abnormality determination threshoH value has been exceeded (YES at step 532), the status estimation unit 121 determines that the status of the monitoring target apparatus 2 is the abnormal state and outpuB abnormality occurrence information to outside (step S41). On the other han4 in a case -55- where the individual abnormality determination threshold value has not been exceeded (NO at step 532), the status estimation unit L21 determines whether the plurality of pieces #1to #n of physical information have exceeded the set of abnormality determination threshold values (step S33). IOLTLl In a case where the set of abnormality determination threshold values has been exceeded (YES at step 533), the status estimation unit l2L determines that the status of the monitoring target apparatus 2 is the abnormal state and outputs abnormality occurrence information to ouBide (step S41). 0n the other han4 in a case where the set of abnormality determination threshoH values has not been exceeded (NO at step 533), the status estimation unit 121 determines that the status of the monitoring target apparatus 2 is not the abnormal state. lOL7Zl When it is determined that the status of the monitoring target apparatus 2 is not the abnormal state, the malfunction prediction unit 122 futermines whether at hast one of the plurality of pieces #1 to #n of physical information has exceeded the individual prediction determination threshold value (step S52). [0173] In a case where the individual prediction determination threshold value has been exceeded (YES at step 552), the malfunction prediction unit L22 &termines that the status of the monitoring target apparatus 2 is the state where a malfunction is predicted to occur within a prefutermined time period (namely, a malfunction has been predicted) and outpuB malfunction prediction information to oubide [step 56f). 101-74l On the other hand the individual prediction determination threshold value has not been exceeded (NO at step S53), the malfunction prediction unit L22 determines whether the plurality of pieces #L to #n of physical information have exceeded the set of malfunction prediction determination threshold values (step S53) -56- [01751 In a case where the set of malfunction prediction determination threshold values has been exceeded (YES at step S53), the malfunction prediction unitt22 determines that the status of the monitoring target apparatus 2 is the state where a malfunction is predicted to occur within a predetermined time period and outpuB malfunction prediction information to ouBifu [step 561). On the other hand, in a case where the set of malfunction prediction determination threshold values has not been exceeded INO at step S53), the malfunction prediction unitL22 determines that the status of the monitoring target apparatus 2 is not the state where a malfunction is predicted to occur within a predetermined time period and outpuB a piece of apparatus status information corresponding to the status of the monitoring target apparatus 2 to ouBide (step S72). lO176l Fig. 20 is an explanatory view for explaining a malfunction prediction process based on a combination of a plurality of pieces of physical information in the operation examph of the apparatus status monitoring device 1 according to the seventh modification example of this embodiment. Fig. 20 shows, as a result of a comparison between the pieces #1 to #3 of physical information and the individual prediction determination threshold values corresponding thereto, a magnitude relationship between each of respective degrees of agreement of time-dependent information of the pieces #1 to #3 of physical information and a corresponding one of the individual prediction determination threshold values. Furthermore, Fig. 20 also shows, as result of a comparison between the combination of the pieces #L to #3 of physical information and the corresponding set of malfunction prediction determination threshoH values, a magnitude relationship between each of respective degrees of agreement of time-&pendent information of the pieces #L to #3 of physical information and the set of malfunction prediction determination threshold -57 - values. l0t77l In an example shown in Fig. 20, the respective degrees of agreement of timedependent information of the pieces #1 to #3 of physical information are all smaller than the individual prediction determination threshoh values corresponding respectively thereto. Because of this, in the example shown in Fig. 20, a negative determination result is obtained in the malfunction prediction determination based on a comparison with the individual prediction determination threshold value (step S52), which is shown in Fig. 19. 0n the other han{ in the example shown in Fig. 20, a combination of the respective degrees of agreement of time-dependent information of the pieces #1 to #3 of physical information is larger than the set of malfunction prediction determination threshoH values. Because of this, in the examph shown in Fig. 20, a positive determination result is obtained in the malfunction prediction determination based on a comparison with the set of malfunction prediction determination threshold values (step 553), which is shown in Fig. 19. That is, in the example shown in Fig. 20, it is determined that there is established the state where a malfunction is predicted to occur within a predetermined time period [0178] According to the seventh modification example, with both of the individual abnormality determination threshoH value and the set of abnormality determination threshoh values used as a basis, the abnormal state can be properly detected Furthermore, with both of the individual prediction determination threshold value and the set of malfunction prediction &termination threshoH values used as a basis, future occurrence of a malfunction can be properly predicted l0l79l (Eighth Modification Examph) Next, a description is given of an eighth modification exampb in which a status of the monitoring target apparatus 2 is -58- determined by using, as a criterion, a strtus of the monitoring target apparatus 2 ata startup that is an operation start time. Herein, the operation start time refers to, for examph, a time when the monitoring target apparatus 2, which had been stopped from operating during the night, is started to operate again the next morning. Fig.2l is an explanatory view for explaining a process of determining a status of the monitoring target apparatus 2 in an operation examph of an apparatus status monitoring device 1 according to the eighth modification example of this embodiment. [01801 In the eighth modification examph, as physical information regarding the surface 3a of the industrial robot 30A, an information acquisition unit ll acquires a displacement of each of the respective surfaces of the first to third rotation shafts 306 to 308 (see Fig. 21). There is no particular limitation on a specific method for acquiring a displacement of each of the respective surfaces of the first to third rotation shafts 306 to 308. For example, based on a captured image, which is captured by a camera 100, of a mark provided at a particular position on each of the surfaces of the first to third rotation shafo 306 to 308, the information acquisition unit 11 may acquire a trajectory of the mark as a displacement of the each of the surfaces of the first to third rotation shafts 306 to 308. [01811 At both of a startup of the industrial robot 30A and a time of determining an apparatus status, the information acquisition unit 11 acquires a displacement of each of the surfaces of the first to third rotation shafts 306 to 308. At both of the startup and the time of determination, a conffol device 120 inpuB a common operation command to the industrial robot 30A, and the information acquisition unit 11 acquires a displacement of each of the surfaces of the first to third rotation shafts 306 to 308 of the indusfrial robot 30A, which operate under the common operation command -59- [01821 With respect to each of the first to third rotation shafts 306 to 308, the control device 120 cahulates an error fhereinafter; referred to also as a displacement error) between a displacement of each of the surfaces at the startup and a displacement of the each of the surfaces at the determination time. There is no particular limitation on specific aspecB of a displacement erroI and a displacement error may be, for examph, a difference in total displacement amount (for example, a moving distance of the mark) in a case where an operation is performed under the previously mentioned common operation command Based on a result of a comparison between the thus cabulated displacement error and a threshold value, the contol device 120 determines whether any of the first to third speed reducers 308-1 to 308-3 built in the first to third rotation shafu 306 to 308, respectively, is in the abnormal state. In a case where the displacement error has exceeded the threshoH value, the control device 120 determines that the any of the speed reducers 308-L to 308-3 is in the abnormal state. [01831 In determining presence or absence of the abnormal state, the control device L20 may perform a determination in consideration of respective positions of the surfaces whose displacemenB are to be acquired For examph, in an example shown in Fig.2L, the third rotation shaft 308 is disposed at a position more distant from the mounting position P than respective portions of the first rotation shaft 306 and the second rotation shaft 307. Because of this, there is a possibility that a displacement error of the third rotation shaft 308, with respective disphcement errors of the first and second rotation shafts 306 and 307 added thereto, becomes larger than each of the respective displacement errors of the first and second rotation shafs 306 and 307. Thus, in determining presence or absence of the abnormal state, a threshold value of the displacement error of the third rotation shaft 308 may be set to be larger than a -60- threshold value of each of the respective displacement errors of the first rotation shaft 306 and the second rotation shaft 307. By this configuration, a status of the third speed reducer 308-3 built in the third rotation shaft 308 can be determined with accuracy. [0184] According to the eighth modification example, it is determined whether the speed reducer 308 is in the abnormal state by using a status thereof at a startup as a criterion, and thus an influence of a disturbance such as an error in physical information attributable to a difference in use environment such as a season or a temperahrre is reduced, so that accuracy in determining a status of the speed reducer 30B can be improved While the foregoing has described a determination of the abnormal state, the same applies to a determination of the state in which a malfunction is predicted to occur within a prefutermined time period [01851 Furthermore, by using a stahrs of the speed reducer 30B at a time of installing the industrial robot 30A as a criterion, the contol device L20 may determine whether the speed reducer 30B is in a predetermined sate. With the status at the time of installation used as a criterion, timing for replacing the speed reducer 30B due to aging deterioration thereof can be grasped [01861 [Ninth Modification Example) Next, a description is given of, as a ninth modification example, an examph of an operation checking device provided with the apparatus status monitoring device 1. Fig. 22 is a view showing an operation checking device 10 according to the ninth modification example of this embodiment. [0187] The operation checking device L0 is provided with the apparatus status monitoring device L and a computer B. The operation checking device l-0 checks an operation of the industial robot 30A in a virtual space on a storage region B1 of the -67- computer B. In an example shown in Fig. 22,the operation checking device L0 checks, in the virtual space, an operation of each of a plurality of industial roboB 30A arranged in a real space so as to form a production line. While in the examph shown in Fig. 22, one apparatus status monitoring device 1 is provided with respect to each of the industial robob 30A, it is not necessarily required that the number of the apparatus status monitoring devices 1 agree with the number of the industrial robots 30A. For examph, one apparatus shtus monitoring device 1 may monitor a status of the plurality of industrial robots 30A. [01881 The operation checking device 10 has an input unit 82. The input unit 82 inpuB information acquired by the apparatus status monitoring device L as information related to a status of the industrial robot 30A. The information acquired by the apparatus status monitoring device 1 is, for examph, the previously mentioned acquired information by the apparails stahrs determination unit L2 (namely, the abnormality occurrence information, the malfunction prediction information, and the apparatus status information). The information acquired by the apparatus status monitoring device 1 may include physical information acquired by the information acquisition unit L1. The input unit 82 may be, for example, a CPU. The input unit 82 may periodically acquire information from the apparatus status monitoring device 1 and input the information. [01891 According to the ninth modification example, an updated operation status of the indusffial robot 30A in the real space can be checked on the virtual space. By this configuration, an operation of the indusffial robot 30A in the real space can be simulated on the virtual space. Furthermore, it also becomes possible to reflect, in the real space, a simulation result of making a process change on the virtual space. -62- [01901 (Tenth Modification Example) Next, a description is given of a tenth modification example in which a status of a monitoring target 20 built in a civil engineering. buiHing sffucture 30L is monitored by using an apparatus status monitoring device 1. Fig. 23 is a bhck diagram showing the apparatus stails monitoring device l- according to the tenth modification examph of this embodiment. In an example shown in Fig. 23,the apparatus status monitoring device 1 is independent of the civil engineering . building sffucture 30L. [01911 Examples of the civil engineering . building structure 30L include a wind turbine for wind power generation, a heliostat of a solar thermal power generation towe[ an elevated road, a bridge, and a building. Examples of the monitoring target 20 include structural members such as a steel frame or a reinforcing steel bar provided in an insi& of the civil engineering. buiHing structure 30L, fastening members such as a bolt provided in said inside, and various types of piping for water supply and sewage and for ehctric wiring embedded inside. Further examphs of the monitoring target 20 include civil engineering or building sffuctures made of concrete, such as a wind turbine for wind power generation, a solar thermal power generation towe4 an ehvated road, a bridge, and a building, and a portion inside said concrete. l0l92l Furthermore, other examphs of the civil engineering. building structure 30L include a road and a sidewalk, in which case examphs of the monitoring target 20 include a common groove, a water pipe, a gas pipe and the like buried under the road or the sidewalk, and a connection portion thereof. [01931 Other features are the same as those in this embodiment and the other modification examples of this embodiment and thus will not be described herein [0194] While the foregoing embodiment and modification examphs have mainly -63- described status monitoring, there is no limitation theretg and a status of the monitoring target apparatus 2 may be checked only in any given time period at any given timing as required In this case, physical information may be acquired by the information acquisition unit 11 only in any given time period at any given timing. Furthermore, it may also be possibh that the information acquisition unit lL acquires physical information in a continuous manne4 and the apparahrs status determination unit 12 performs a determination only in any given time period at any given timing. [01951 The foregoing embodiment and modification examples may be combined as appropriate, and unless otherwise indicated, the individual configurations described in the foregoing embodiment and modification examphs may be combined in any given way, or a part thereof may be omitted [0196] AspecB of the present invention are not limited to the foregoing embodiment and embrace various modifications conceivable by those skilhd in the art. EffecB of the present invention are also not limited to the above-mentioned contenB. That is, various additions, changes, and partial dehtions are possible in a range of not departing from the conceptual ideas and spirit of the present invention derived from contenB defined in the chims and equivalents thereof. -64- WHAT IS CLAIMED IS: 1,. A status checking device for a built-in object, comprising: an information acquisition unit for acquiring one or more pieces of physical information regarding an article including a target built therein, a status of the target being unabb to be directly checked from ouBide, the one or more pieces of physical information being manifested ouBide the article; and a status determination unit for determining the status of the target based on the acquired one or more pieces of physical information. 2. The status checking device for a built-in object according to claim 1, wherein the information acquisition unit acquires a plurality of pieces of physical information, and the status determination unit futermines a status of the target based on the acquired plurality of pieces of physical information. 3. The status checking device for a built-in object according to claim t or 2, wherein the status determination unit has an abnormality determination unit for determining whether the target is in an abnormal state. 4. The status checking device for a built-in object according to claim 3, wherein the abnormality determination unit determines whether the target is in the abnormal state based on at least one of a result of a comparison between the acquired plurality of pieces of physical information and abnormality determination threshold values corresponding respectively to said plurality of pieces of physical information and a -65- result of a comparison between a combination of the acquired plurality of pieces of physical information and a combination of abnormality determination threshold values corresponding to said combination of the plurality of pieces of physical information. 5 The status checking fuvice for a built-in object according to any one of claims 1 to 4, wherein the status determination unit has a malfunction prediction unit for determining whether the target is in a state where a malfunction is predicted to occur within a predetermined time period 6. The stails checking device for a built-in object according to claim 5, wherein the malfunction prediction unit determines whether the target is in the state where a malfunction is predicted to occur within a predetermined time period based on at hast one of a result of a comparison between the acquired plurality of pieces of physical information and malfunction prediction determination threshold values corresponding respectively to said plurality of pieces of physical information and a result of a comparison between a combination of the acquired plurality of pieces of physical information and a combination of malfunction prediction determination threshoH values corresponding to said combination of the plurality of pieces of physical information. 7 . The status checking device for a built-in object according to any one of claims L to 4, wherein the status determination unit has a malfunction prediction unit for determining whether the target is in the state where a malfunction is predicted to occur within a -66- predetermined time period based on a status determination model generated from history information, the history information being a result of determining a stahrs of the target based on the acquired one or more pieces of physical information. B. The status checking device for a built-in object according to claim 7, wherein the status determination model is composed of trnro models, the two models being a malfunction state model generated from the history information as obtained when a malfunction has occurred in the target and a normal state model generated from the history information as obtained when a malfunction has not occurred in the target, and when the target is in a state more analogous to the malfunction state model than to the normal state model, the malfunction prediction unit determines that the target is in the state where a malfunction is predicted to occur within a predetermined time period 9. The status checking device for a built-in object according to any one of claims 1 to B, wherein the one or more pieces of physical information manifested ouBide the article include a piece of physical information regarding a surface of the artich. 10. The status checking device for a built-in object according to claim 9, wherein the piece of physical information regarding the surface of the article includes at least one of properties of the surface of the article including a temperature, a position, a stain, a displacement, a vibration, a hue, a brightress, a saturation, a moisture content, an oil content, and a reflectance of a sound wave, ulffasound, infrared light, or any other type of light. -67 - 7L. The status checking device for a built-in object according to any one of claims 1 to 9, wherein the one or more pieces of physical information manifested ouEide the article include at least one of a sound an odo4 ultrasound an electromagnetic wave, radiation, and an emission, which are detected ouEide the article. L2. The status checking device for a built-in object according to claims 9 or lO,wherein the information acquisition unit acquires the piece of physical information based on a captured image of at least a part of the surface of the article 13. The status checking device for a built-in object according to claim l-2, wherein a thermochromic member whose color changes depending on a temperature is provided on the surface of the article, and the information acquisition unit acquires a temperature of the surface of the artich based on a captured image of the thermochromic member. 14. The status checking device for a built-in object according to claims LZ or 73, wherein the information acquisition unit has an enlarged image capturing function of capturing an enlarged image of at least a part of the surface of the article. 15. The status checking device for a built-in object according to claims t3 or 14, further comprising a drive unit for driving the information acquisition unit to change an image capturing range. 1.6. The status checking device for a built-in object according to any one of claims 13 to 15, wherein the information acquisition unit has a plurality of cameras for capturing images of different areas on the surface of the article. -58- L7. The status checking device for a built-in object according to chim 16, wherein the plurality of cameras are disposed so as to surround the article. 18. The status checking device for a built-in object according to any one of claims 13 to L5, wherein the information acquisition unit has: a drone equipped with a camera; and a drone contol unit for capturing an image of the surface of the artich with the camera. t9. The status checking device for a built-in object according to any one of claims 13 to LB, wherein the information acquisition unit has an optical system capabh of wide-angle or omnidirectional image capturing. 20. The status checking device for a built-in object according to any one of claims 13 to 19, wherein the information acquisition unit acquires a three-dimensional shape of at hast a part of the surface of the article based on the captured image, and acquires the piece of physical information based on the acquired three-dimensional shape. 2L. The status checking device for a built-in object according to any one of claims \3 to 20, wherein the information acquisition unit is disposed away from the surface of the article and disposed at least above the article. 22. The status checking device for a built-in object according to any one of claims L -69- to 2t, wherein, by using a status of the article at a time of construction or installation as a criterion, the status determination unit determines whether or not the target is in an abnormal state or a state where a malfunction is predicted to occur within a predetermined time period 23. The status checking device for a built-in object according to any one of claims 1 to 22, wherein the article is to be operated and by using a status of the article at a start of the operation as a criterion, the status determination unit determines whether or not the target is in an abnormal state or a state where a malfunction is predicted to occur within a predetermined time period 24. The status checking device for a built-in object according to any one of claims L to 23, wherein in a case where a first piece of physical information agrees with a second piece of physical information, the first piece of physical information being acquired previously as a piece of physical information obtained when the target is in an abnormal state or a state where a malfunction is predicted to occur within a pre&termined time period, the second piece of physical information being acquired at any time by the information acquisition unit, the status determination unit determines that the target is in the abnormal state or the state where a malfunction is predicted to occur within a predetermined time period 25. The status checking device for a built-in object according to any one of claims 1 to24, wherein the article is an industrial robot having at least one rotation shaft, the target is a speed reducer built in the at least one rotation shaft, and -70- the information acquisition unit acquires physical information regarding a surface of the at least one rotation shaft. 26. An operation checking device for checking, in a virtual space on a compute[ an operation of an article including a target built therein, a status of the target being unable to be directly checked from ouBide, wherein a status of the target acquired by the status checking device for a builtin object according to any one of claims t to 25 is inputted as information related to a status of the artich. 27. A method for checking a status of a built-in obiect, comprising steps of: acquiring at least one piece of physical information regarding an article including a target built therein, a status of the target being unabh to be directly checked from ouEide, the at least one piece of physical information being manifested oubide the article; and determining whether or not the target is in an abnormal state or a state where a malfunction is predicted to occur within a predetermined time period based on the acquired at least one piece of physical information.