DESCRIPTION
EMERGENCY STOP SYSTEM
Technical Field [0001]
The present invention relates to an emergency stop system to stop, in case of emergency, an industrial machine with a moving part such as a crane. Background Art [0002]
An industrial machine with a moving part such as a crane, is equipped with an emergency stop function (hereinafter referred to as "emergency stop device") which forces to stop the machine (hereinafter referred to as "emergency stop") regardless of its normal operation or the state of the machine, in order to avoid dander such as an approach of the moving part to a human hody by stopping the moving part. The emergency stop control is conducted by an emergency stop switch arranged on an operation panel or a console of the industrial machine. [0003]
In recent years, by realizing the functions equivalent to the operation panels, consoles or the like of the industrial machines with portable terminals (hereinafter referred to as control terminals), the number of industrial machines has been increasing whose emergency stop devices on the moving part sides can be operated from the control terminals connected with wired or wireless communication linkage.
In such a case, an emergency stop switch is also arranged on the control terminal. [0004]
For the industrial machines having such a configuration, a proposed system is to continuously transmit signals (for example, carrier wave) from the control terminal to the emergency stop device while the emergency stop switch is not depressed, and to stop the signal transmission from the control terminal to the emergency stop device once the emergency stop switch is depressed (for example, Patent Document l). Prior Art Reference Patent Document [0005]
Patent Document 1
Japanese Patent Application Publication No. H10-29534 Summary of Invention Problem(s) to be solved by the Invention [0006]
If a conventional emergency stop device has accidentally fallen in a state where signals cannot be received from the control terminal side due to reasons such as disconnection of media, attenuation caused by communication distance or the like, and external interference in the wireless communication linkage, the signals stop, so that the moving part will be stopped even if the emergency stop switch is not depressed.
It is a desirable operation for safety reasons to stop the moving part, as described above, regardless of the state whether or not the emergency stop switch is depressed when the emergency stop device cannot receive signals from the control terminal side.

[0007]
In areas such as factories, however, the emergency stop device described above may frequently become unable to receive signals from the control terminal side for reasons such as the communication linkage being affected by high level noise.
It is desirable for safety to stop the moving part whenever the emergency stop device 6 faces the situation as described above. In the foregoing operation, however, the moving part may be stopped so frequently, even when not actually needed, that the availability of the industrial machine will be significantly impaired.
Means for Solving the Problems [0008]
The present invention is made to solve the problems described above and provides an emergency stop system including a switch to instruct an industrial machine to stop at least one moving part, a detector to stop transmission of a radio signal that is continuously transmitted, when stopping is instructed by the switch, a stop time calculation unit to calculate a stop time to be used for determining whether to stop the moving part or not on the basis of an operating state of the moving part, and a stop determination unit to stop the moving part when a state of not receiving the radio signal continues until the stop time elapses since suspension of receiving the radio signal outputted from the detector.Effects of the Invention [0009]
According to the present invention, emergency stop control can be performed without impairing availability of industrial machines. Brief Description of the Drawings [0010]
Fig. 1 is a diagram which shows an example of a system configuration of an industrial machine which uses an emergency stop device in Embodiment 1.
Fig. 2 is a diagram which shows an example of a configuration of a control terminal in Embodiment 1.
Fig. 3 is a diagram which shows an example of a configuration of the emergency stop device in Embodiment 1.
Fig. 4 is a flowchart which shows the operation of the emergency stop device in Embodiment 1.
Fig. 5 is a diagram which shows an example of a configuration of an emergency stop device and an industrial machine in Embodiment 2.
Fig. 6 is a flowchart which shows the operation of the emergency stop device in Embodiment 2.
Embodiments for Carrying Out the Invention [0011] Embodiment 1
Fig. 1 is a diagram which shows an example, of system configuration of an industrial machine which uses an emergency stop device in the present embodiment.
In Fig. 1, numeral 1 denotes the industrial machine, which has a moving part 2. The moving part 2 is a movable device such as various types of cranes, automatic carriers, press machines, and hoists. While Fig. 1 explains a case where there is only one moving part 2, there may be a plurality of them. [0012]

A control terminal 3 is a terminal to control the industrial machine 1 from a physically remote place.
Communication linkage 4 is used to connect the industrial machine 1 and the control terminal 3 via wireless communication.
An emergency stop control unit 5 is arranged on the control terminal 3 and is used when an operator judges that a dangerous situation, such as an approach of a human body to the moving part 2, has occurred.
The emergency stop device 6 is connected with the emergency stop control unit 5 via the communication linkage 4 and receives an instruction from the emergency stop control unit 5. When the emergency stop device 6 has received a stop instruction from the emergency stop control unit 5, it outputs an instruction to the industrial machine 1 to stop the moving part 2. [0013]
The emergency stop control unit 5 has several methods to output a signal indicating the state of emergency stop control to the communication linkage 4. In the present invention, any method with which the emergency stop device 6 can determine the state of the emergency stop control unit 5 by observing a radio signal (hereinafter referred to as a signal) on the communication linkage 4 may be used.
For example, the emergency stop control unit 5 may output signals indicating whether or not an emergency stop control has been conducted to the communication linkage 4 at a fixed time interval (periodically) or continuously. [0014]
Fig. 2 is a diagram which shows an example of a configuration of the emergency stop control unit 5 in the embodiment.
As shown in Fig. 2, the emergency stop control unit 5 includes a switch 51 and a detector 52.
The switch 51 is to be depressed when the operator judges that a dangerous state, such as an approach of a human body to the moving part 2, has occurred.
The switch 51 outputs a state whether or not it is depressed to the detector 52. Note that the switch 51 may either output a signal indicating that it is depressed when it is depressed, or continuously output signals while the switch is not depressed and stop the signals once it is depressed.
The detector 52 outputs a state outputted from the switch 51, indicating whether or not the switch 51 is depressed, to the communication linkage 4. While the switch 51 is not depressed, the detector 52 keeps transmitting signals (continuously or periodically) indicating that the emergency stop control has not been conducted. When the switch 51 is depressed, the detector 52 stops the transmission of signals indicating that the emergency stop control has not been conducted. [0015]
Fig. 3 is a diagram which shows an example of a configuration of the emergency stop device in the embodiment.
As shown in Fig. 3, the emergency stop device 6 includes a stop determination unit 61, a measurement unit 62 and a stop time calculation unit 63.
The stop determination unit 61 receives the information on the switch 51 outputted from the detector 52 via the communication linkage 4.
The stop determination unit 61 checks whether or not a signal indicating that the switch 51 is not depressed is received until a stop time Relapses after the

stop determination unit 61 stopped receiving the signals indicating that the switch 51 is not depressed.
The stop determination unit 61 stops the moving part 2 if a signal indicating that the switch 51 is not depressed is not received by the time when the stop time Relapses.
If a signal indicating that the switch 51 is not depressed is received by the time when the stop time Relapses, the stop determination unit 61 keeps the moving part 2 operating, judging not that the switch 51 has been depressed but that the signal has been unable to be received due to temporary disconnection of the communication linkage 4. [0016]
The measurement unit 62 measures the velocity of the moving part 2 using a velocity meter, and outputs the measurement result to the stop time calculation unit.
In this embodiment, the measurement unit 62 is explained as a part of the emergency stop device 6. However, it can be a part of the industrial machine 1 or independent from the industrial machine 1 and the emergency stop device 6.
Further, the measurement unit 62 may measure the velocity information to the stop time calculation unit 63 at a fixed time interval (periodically) or continuously. [0017]
The stop time calculation unit 63 calculates the stop time t from the velocity outputted from the measurement unit 62 and outputs the calculation result to the stop determination unit 61. [0018]
Among methods to calculate the stop time t, there is a method to determine the stop time so as to keep the free running distance of the moving part 2 constant. For example, when the free running distance is set to 3 m, if the velocity of the moving part is 1.5 m/sec, then the stop time tis calculated as 3 / 1.5 — 2 seconds. [0019]
The calculation of the stop time t by the stop time calculation unit 63 may be done regardless of the measurement value (velocity here), may be done when the measurement value has reached a predetermined value, or may be done when the variation of the measurement value (for example, the difference from the last measurement result) has reached a predetermined value. [0020]
Further, the timing at which the stop time calculation unit 63 outputs the stop time t to the stop determination unit 61 may be on a fixed time interval (periodically) basis, on a continuous basis, or on a "responding to an inquiry from the stop determination unit 61" basis. [0021]
Fig. 4 is a flowchart which shows the operation of the emergency stop device in this embodiment.
In Step S401, the stop determination unit 61 receives information on the switch outputted from the emergency stop control unit 5. [0022]
In Step S402, the stop determination unit 61 determines whether or not the switch 51 is depressed. Note that "the state where the switch 51 is depressed" may possibly be a state where signals cannot be received.

If a signal indicating that the switch 51 is not depressed is received (Step
S402: NO), the flow ends.
If a signal indicating that the switch 51 is not depressed is unreceived
(Step S402: YES), the stop time calculation unit 63 calculates, in Step S403, the
stop time t from the information (for example, velocity of the moving part 2)
outputted from the measurement unit 62, and outputs the calculation result to the
stop determination unit 61.
[0023]
In Step S404, the stop determination unit 61 judges whether or not it has
received a signal indicating that the switch 51 is not depressed by the time when
the stop time Relapses.
If the stop determination unit 61 has received a signal indicating that the
switch 51 is not depressed by the time when the stop time Relapses (Step S404:
YES), the flow ends.
[0024]
If the stop determination unit 61 has not received a signal indicating that
the switch 51 is not depressed by the time when the stop time Relapses (Step S404:
NO), the stop determination unit 61 outputs, in Step S405, an instruction to stop
the moving part 2 to the industrial machine 1.
The industrial machine 1 stops the moving part 2 when it receives a stop
instruction outputted from the stop determination unit 61.
[0025]
Note that, in this embodiment, the velocity of the moving part 2 outputted
from the measurement unit 62 is used in order for the stop time calculation unit 63
to calculate the stop time t In the same way, the acceleration of the moving part 2,
or the combination of the acceleration and the velocity can be used.
[0026]
As explained above, due to reasons such that the emergency stop device 6
is not able to receive signals from the control terminal 3, if the state in which the emergency stop device 6 has not received a signal indicating that the switch 51 is not depressed continues for a certain period of time, safety can be ensured by stopping the moving part 2 regardless of the state of the switch 51.
[0027]
In addition, the time from suspension of receiving the signals indicating that the switch 51 is not depressed until stopping of the moving part 2 is determined in accordance with the state of the moving part 2 (for example, velocity). Then, by assessing how long the time during which a signal indicating that the switch 51 is not depressed has not been received continues, the time until stopping can be changed in accordance with the probability of posing actual hazard. Thus, the moving part 2 can be prevented from being stopped despite a low probability of hazard occurrence (for example, when the moving part 2 operates at a significantly low velocity). This leads to extension of operation time of the moving part 2 to enhance the availability. [0028] Embodiment 2
In Embodiment 1, in order for the stop time calculation unit to calculate the stop time t, the velocity or the acceleration of the moving part 2 outputted from the measurement unit 62, or the combination of the velocity and the acceleration are used. In the present embodiment, it is explained to use a distance between the moving part 2 and an object existing in the vicinity of the moving part 2.

Fig. 5 is a diagram which shows an example of configuration of an emergency stop device 6 and an industrial machine 1 in'the embodiment. [0029]
In Fig. 5, a sensor 64, moving together with the moving part 2, is a distance sensor which uses infrared rays, ultrasonic wave or visible light and so forth to evaluate or calculate the reflection to convert into a distance to output.
In the embodiment, the sensor 64 is explained as moving together with the moving part 2. However, the sensor 64 may be a part of the industrial machine 1 other than the moving part 2, or a part of the emergency stop device 6, or even independent from any of the industrial machine 1, the moving part 2 and the emergency stop device 6, in so far as the sensor 64 can detect the positions of both the moving part 2 and the object existing in the vicinity of the moving part 2. [0030]
In Fig. 5, the same symbols as used in Fig. 3 indicate the same or the equivalent portions, and the components except a stop time calculation unit 63 and the memory 64 operate in the same manner as those described in Fig. 3 in Embodiment 1.
In Embodiment 1, the stop time calculation unit 63 calculated the stop time t from the velocity information outputted from the measurement unit 62. In the present embodiment, the distance between the moving part 2 and the object existing in the vicinity, which is outputted from the sensor 64, is used. [0031]
The method to calculate the stop time is as follows. For example, when the velocity of the moving part 2 is constant at 2 m/sec and the allowable distance for safe stop is 1 m, if the distance between the moving part 2 and the object is 4 m, then the stop time £is calculated as (4-1) / 2 = 1.5 seconds.
Even in a case where the actual velocity of the moving part 2 is unknown, if the maximum velocity of the moving part 2 is known as 3 m/sec, when the distance between the moving part 2 and the object existing in the vicinity of the moving part 2, for example, is 10 m, and the allowable distance for safe stop is 1 m, then the stop time £can be calculated as (10-1) / 3 - 3 seconds. [0032]
Fig. 6 is a flowchart which shows the operation of the emergency stop device in the embodiment.
As the operation in Embodiment 2 is the same as the procedure described in Embodiment 1, only the difference from the operation illustrated in Embodiment 1 will be explained below. [0033]
In Step S603, the stop time calculation unit 63 calculates the stop time ton the basis of the information (distance between the moving part 2 and the object existing in the vicinity of the moving part 2) outputted from the sensor 64, and outputs the calculation result to the stop determination unit 61. [0034]
In the example above, the distance between the moving part 2 and the object existing in the vicinity is used. In the same way, the distance of the moving part 2 from the area where the object may exist can be used. For example, the area where an operator may position is predetermined and the assessment described above will be conducted on the basis of the distance therefrom. [0035]

The stop time calculation unit 63 may receive together information from the measurement unit 62 explained in Embodiment 1 and information from the sensor 64 explained in the present embodiment to calculate the stop time. [0036]
In this embodiment, the sensor 64 measures the distance between the moving part 2 and the object in the vicinity. However, in a case, for example, where multiple moving parts 2 operate, the sensor 64 may measure the distance between the neighboring moving parts. [0037]
If the measurement unit 62 or the sensor 64 can detect the moving directions of the moving parts 2, the stop time can be calculated from the relative velocity between multiple moving parts. For example, when the two moving parts move both at the velocity of 2 m/sec, their maximum relative velocity is 4 m/sec. Then, if the distance between the two moving parts is 11 m and the allowable distance is 1 m, the stop time £is calculated as (ll-l) / 4 = 2.5 seconds. [0038]
As explained above, if the state in which the emergency stop device 6 has not received a signal indicating that the switch 51 is not depressed due to reasons such that the emergency stop device 6 is not able to receive signals from the control terminal 3 continues for a certain period of time, the moving part 2 is stopped regardless of the state of the switch 51, so that safety can be ensured. [0039]
In addition, the time from suspension of receiving the signals indicating that the switch 51 is not depressed until stopping of the moving part 2 is determined in accordance with the state of the moving part 2 (for example, distance). Then, by assessing how long the time during which a signal indicating that the switch 51 is not depressed has not been received continues, the time until stopping can be changed in accordance with the probability of posing actual hazard. Thus, the moving part 2 can be prevented from being stopped despite a low probability of hazard occurrence (for example, when the moving part 2 is significantly distant from the neighboring object). This leads to extension of operation time of the moving part 2 to enhance the availability. Description of Reference Numerals [0040]
1- industrial machine, 2- moving part, 3; control terminal,
4' communication linkage, 5: emergency stop control unit, 6- emergency stop device, 51: switch, 52: detector, 61: stop determination unit, 62: measurement unit, 63: stop time calculation unit, 64: sensor

CLAIMS
1. An emergency stop system comprising-
a switch to instruct an industrial machine to stop at least one moving part;
a detector to stop transmission of a radio signal that is continuously transmitted, when stopping is instructed by the switch!
a stop time calculation unit to calculate a stop time to be used for determining whether to stop the moving part or not on the basis of an operating state of the moving part; and
a stop determination unit to stop the moving part when a state of not receiving the radio signal continues until the stop time elapses since suspension of receiving the radio signal outputted from the detector.
2. The emergency stop system according to claim 1, wherein the stop calculation unit calculates the stop time from the velocity of the moving pai't.
3. The emergency stop system according to claim 1, wherein the stop calculation unit calculates the stop time from the acceleration of the moving part.
4. The emergency stop system according to claim 1, wherein the stop calculation unit calculates the stop time from a distance between the moving part and an object existing in the vicinity thereof.
5. The emergency stop system according to claim 4, wherein the at least one moving part comprises multiple moving parts and the stop time determination unit calculates a stop time from a distance between the multiple moving parts.