The present invention relates to a ground cutting determination device for suppressing load runout when lifting a suspended load from the ground.
Background technology
[0002]
Conventionally, in a crane equipped with a boom, when lifting a suspended load from the ground, that is, when cutting the suspended load, the bending caused by the boom increases the working radius, so that the suspended load swings horizontally. "Load runout" has become a problem (see Fig. 1).
[0003]
For the purpose of preventing load shake during ground cutting, for example, the vertical ground cutting control device described in Patent Document 1 detects the engine rotation speed by an engine rotation speed sensor and raises and lowers the boom. It is configured to correct to a value according to the engine speed. With such a configuration, it is said that accurate ground cutting control can be performed in consideration of changes in engine speed.
Prior art literature
Patent documents
[0004]
Patent Document 1: Japanese Unexamined Patent Publication No. 8-188379
Outline of the invention
Problems to be solved by the invention
[0005]
However, since the conventional ground cutting control device including Patent Document 1 determines the ground cutting based on the time series of the load data, there is a problem that the responsiveness is poor and the ground cutting determination takes time.
[0006]
Therefore, the present invention comprises a ground cutting determination device, a ground cutting control device, a mobile crane, and a ground cutting determination method, which can quickly determine the ground cutting by a simple method while suppressing load shake. Is intended to provide.
Means to solve problems
[0007]
In order to achieve the above-mentioned object, the ground cutting determination device of the present invention has a boom configured to be undulating, a winch for hoisting / hoisting a suspended load via a wire rope, and a load acting on the boom. A load measuring means for measuring, a rope length measuring means for measuring the rope length of the wire rope, and a control unit for controlling the boom and the winch, when the winch is wound up and the suspended load is cut off. It is provided with a control unit that determines ground cutting based on the time change of the measured load and the time change of the measured rope length.
[0008]
Further, the ground cutting control device of the present invention is a ground cutting control device including a ground cutting determination device, in which the control unit winds up the winch and cuts a suspended load by ground cutting. The amount of change in the undulation angle of the boom is obtained based on the time change, and the boom is undulated so as to compensate for the amount of change.
The invention's effect
[0009]
As described above, the ground cutting determination device of the present invention includes a boom, a winch, a load measuring means, a rope length measuring means, a time change of the measured load at the time of ground cutting, and a measured rope length. It is provided with a control unit, which is designed to determine the ground cutting based on the time change of the above. With such a configuration, it is possible to quickly determine the ground cutting by a simple method while suppressing load shake.
[0010]
Further, the ground cutting control device of the present invention is a ground cutting control device including a ground cutting determination device, and the control unit is a boom undulation angle based on a time change of a measured load at the time of ground cutting. The amount of change is calculated, and the boom is undulated to compensate for the amount of change. With such a configuration, it is possible to quickly determine the ground cut and quickly cut the suspended load while suppressing the load runout.
A brief description of the drawing
[0011]
[Fig. 1] It is explanatory drawing explaining the load runout of a suspended load.
[Fig. 2] It is a side view of a mobile crane.
[Fig. 3] It is a block diagram of a ground cutting control device.
[Fig. 4] Fig. 4 is a graph showing the relationship between load and undulation angle.
[Fig. 5] Fig. 5 is a block diagram of the entire ground cutting control device.
[Fig. 6] It is a block diagram of the ground cutting control.
[Fig. 7] It is a flowchart of the ground cutting control.
[Fig. 8] It is a graph explaining the concept of the ground cutting judgment.
[Fig. 9] Fig. 9 is a flowchart illustrating a ground cutting determination method.
Embodiment for carrying out the invention
[0012]
Hereinafter, examples according to the present invention will be described with reference to the drawings. However, the components described in the following examples are examples, and the technical scope of the present invention is not limited to them.
Example
[0013]
In this embodiment, examples of the mobile crane include a rough terrain crane, an all terrain crane, and a truck crane. Hereinafter, a rough terrain crane will be described as an example of the work vehicle according to the present embodiment, but the safety device according to the present invention can also be applied to other mobile cranes.
[0014]
(Structure of mobile crane)
First, the configuration of the mobile crane will be described using the side view of FIG. As shown in FIG. 2, the rough terrain crane 1 of the present embodiment has a vehicle body 10 which is a main body portion of a vehicle having a traveling function, outriggers 11 provided at four corners of the vehicle body 10, ... It includes a swing table 12 mounted so as to be able to turn horizontally, and a boom 14 mounted behind the swing table 12.
[0015]
By expanding and contracting the slide cylinder, the out trigger 11 can slide out / slide outward from the vehicle body 10 in the width direction, and by expanding and contracting the jack cylinder, the jack can be extended / jack stored in the vertical direction from the vehicle body 10. Is.
[0016]
The swivel base 12 has a pinion gear to which the power of the swivel motor 61 is transmitted, and the pinion gear meshes with a circular gear provided on the vehicle body 10 to rotate around a swivel shaft. The swivel table 12 has a cockpit 18 arranged on the right front side and a counterweight 19 arranged on the rear side.
[0017]
Further, behind the swivel table 12, a winch 13 for hoisting / lowering the wire 16 is arranged. By rotating the winch motor 64 in the forward direction / the reverse direction, the winch 13 rotates in two directions, a winding direction (winding direction) and a winding direction (winding direction).
[0018]
The boom 14 is configured in a nested manner by a base end boom 141, an intermediate boom 142 (s), and a tip boom 143, and can be expanded and contracted by an telescopic cylinder 63 arranged inside. A sheave is arranged on the state-of-the-art boom head 144 of the tip boom 143, and a wire rope 16 is hung around the sheave to hang a hook 17.
[0019]
The base portion of the base end boom 141 is rotatably attached to a support shaft installed on the swivel base 12, and can be undulated up and down with the support shaft as the center of rotation. An undulating cylinder 62 is bridged between the swivel base 12 and the lower surface of the base end boom 141, and the entire boom 14 can be undulated by expanding and contracting the undulating cylinder 62. ..
[0020]
(Control system configuration)
Next, the configuration of the control system of the ground cutting control device D of this embodiment will be described with reference to the block diagram of FIG. The ground cutting control device D is configured around a controller 40 as a control unit. The controller 40 is a general-purpose microcomputer having an input port, an output port, an arithmetic unit, and the like. The controller 40 receives an operation signal from the operation levers 51 to 54 (swivel lever 51, undulation lever 52, telescopic lever 53, winch lever 54), and the actuators 61 to 64 (swivel motor 61, via a control valve (not shown)). The undulating cylinder 62, the telescopic cylinder 63, and the winch motor 64) are controlled.
[0021]
Further, the controller 40 of the present embodiment includes a ground cutting switch 20 for starting / stopping the ground cutting control, a winch speed setting means 21 for setting the speed of the winch 13 in the ground cutting control, and a boom 14. The load measuring means 22 for measuring the acting load, the posture detecting means 23 for detecting the posture of the boom 14, and the rope length and hoisting speed measuring means 24 for measuring the rope length of the wire rope 16 are connected. ing.
[0022]
The ground cutting switch 20 is an input device for instructing the start or stop of ground cutting control, and can be configured to be added to the safety device of the rough terrain crane 1, for example, and is arranged in the cockpit 18. Is preferable.
[0023]
The winch speed setting means 21 is an input device for setting the speed of the winch 13 in ground cutting control, and includes a method of selecting an appropriate speed from preset speeds and a method of inputting by a numeric keypad. .. Further, the winch speed setting means 21 can be configured to be added to the safety device of the rough terrain crane 1 like the ground cutting switch 20, and is preferably arranged in the cockpit 18. By adjusting the speed of the winch 13 by the winch speed setting means 21, the time required for ground cutting control can be adjusted.
[0024]
The load measuring means 22 is a measuring device that measures the load acting on the boom 14, and can be, for example, a pressure gauge (22) that measures the pressure acting on the undulating cylinder 62. The pressure signal measured by the pressure gauge (22) is transmitted to the controller 40.
[0025]
The posture detecting means 23 is a measuring device for detecting the posture of the boom 14, and includes an undulation angle meter 231 for measuring the undulation angle of the boom 14 and an undulation angular velocity meter 232 for measuring the undulation angular velocity. Specifically, a potentiometer can be used as the undulation angle meter 231. Further, as the undulation angular velocity meter 232, a stroke sensor attached to the undulation cylinder 15 can be used. The undulation angle signal measured by the undulation angle meter 231 and the undulation angular velocity signal measured by the undulation angular velocity meter 232 are transmitted to the controller 40.
[0026]
The rope length and hoisting speed measuring means 24 measures the rope length of the wire rope 16, and can be, for example, a rotation speed meter (so-called rotary encoder) that measures the rotation speed of the winch motor 64. Since this rotation speed meter directly measures the rotation speed of the winch 13, it has extremely good responsiveness. As a matter of course, the rope length and hoisting speed measuring means 24 can detect the time change of the rope length, so that the rope length and hoisting speed measuring means 24 can also be used as the hoisting speed measuring means.
[0027]
The controller 40 is a control unit that controls the operation of the boom 14 and the winch 13, and is measured by the load measuring means 22 when the winch 13 is wound up and the suspended load is grounded by turning on the ground cutting switch 20. The amount of change in the undulation angle of the boom 14 is predicted based on the time change of the applied load, and the boom 14 is undulated so as to compensate for the predicted amount of change.
[0028]
More specifically, the controller 40 has, as a functional unit, a characteristic table or a transfer function selection function unit 40a, and a ground cutting determination function for stopping the ground cutting control by determining whether or not the ground cutting has actually been performed. It has a portion 40b and.
[0029]
The selection function unit 40a of the characteristic table or the transfer function receives inputs of the initial value of the pressure from the pressure gauge 22 as the load measuring means and the initial value of the undulating angle from the undulating angle meter 23 as the attitude measuring means. To determine the characteristic table or transfer function to apply. Here, as the transfer function, a relationship using the linear coefficient a can be applied as follows.
[0030]
First, as shown in the load-undulation angle graph in FIG. 4, the load and undulation angle (tip-to-ground angle) are adjusted so that the boom tip position is always directly above the suspended load so that load runout does not occur. ) Is known to have a linear relationship. Assuming that the load Load 1 changed to Load 2 between time t1 and time t2 during the ground cutting,
[Number 1]

[0031]
When the difference equation is obtained from the difference between the two equations,
[Number 2]

[0032]
In order to control the undulation angle, it is necessary to give the undulation angular velocity.
[Number 3]

Here, a is a constant (linear coefficient).
That is, in the undulation angle control, the time change (derivative) of the load is input.
[0033]
Ground cutting judgment function unit 40 b monitors the time-series data of the load value calculated from the pressure signal from the pressure gauge 22 as the load measuring means, and determines whether or not there is a ground cut. The method of determining the ground cutting will be described later with reference to FIG.
[0034]
(Overall block diagram)
Next, using the block diagram of FIG. 5, the input / output relationship between all the elements including the ground cutting control of this embodiment will be described in detail. First, the load change calculation unit 71 calculates the load change based on the time series data of the load measured by the load measuring means 22. The calculated load change is input to the target shaft velocity calculation unit 72. The input / output relationship in the target axis speed calculation unit 72 will be described later with reference to FIG.
[0035]
The target shaft speed calculation unit 72 calculates the target shaft speed based on the initial value of the undulation angle, the set winch speed, and the input load change. The target axis velocity is here the target undulation angular velocity (and, but not required, the target winch velocity). The calculated target axis speed is input to the axis speed controller 73. The control of the first half up to this point is the process related to the ground cutting control of this embodiment.
[0036]
After that, the operation amount is input to the control target 75 via the axis speed controller 73 and the operation amount conversion processing unit 74 of the axis speed. The control of the latter half is a process related to normal control, and feedback control is performed based on the measured undulation angular velocity.
[0037]
(Block diagram of ground cutting control)
Next, using the block diagram of FIG. 6, the input / output relationship of the elements in the target axis speed calculation unit 72 of the ground cutting control will be described in particular. First, the initial value of the undulation angle is input to the selection function unit 81 (40a) of the characteristic table / transfer function. In the selection function unit 81, the most appropriate constant (linear coefficient) a is selected by using a characteristic table (lookuptable) or a transfer function.
[0038]
Then, in the numerical differentiation unit 82, the numerical differentiation (differentiation with respect to time) of the load change is performed, and the target undulation angle velocity is calculated by multiplying the result of this numerical differentiation by the constant a. That is, the target undulation angular velocity is calculated by executing the above-mentioned calculation (Equation 3). In this way, the control of the target undulation angular velocity is feedforward controlled using the characteristic table (or transfer function).
[0039]
(flowchart)
Next, the overall flow of the ground cutting control of this embodiment will be described using the flowchart of FIG. 7.
[0040]
First, the operator presses the ground cutting switch 20 to start the ground cutting control (START). At this time, the target speed of the winch 13 is set via the winch speed setting means 21 before or after the start of the ground cutting control. Then, the controller 40 starts winch control at the target speed (step S1).
[0041]
Next, at the same time that the winch 13 is wound up, the suspended load measurement is started by the load measuring means 22, and the load value is input to the controller 40 (step S2). Then, the selection function unit 40a receives the input of the initial value of the load and the initial value of the undulation angle from the undulation angle meter 23 as the posture measuring means, and determines the characteristic table or the transfer function to be applied ( Step S3).
[0042]
Next, in the controller 40, the undulation angular velocity is calculated based on the applied characteristic table or transfer function and the load change (step S4). That is, the undulation angular velocity is controlled by the feedforward control.
[0043]
Then, the presence or absence of ground cutting is determined based on the time-series data of the measured load (step S5). The determination method will be described later. As a result of the determination, if the ground is not cut (NO in step S5), the process returns to step S2 and the feedforward control based on the load is repeated (steps S2 to S5).
[0044]
As a result of the determination, if the ground is cut (YES in step S5), the ground cutting control is slowly stopped (step S6). That is, the rotary drive of the winch 13 by the winch motor is stopped while slowing down, and the undulating drive by the undulating cylinder 62 is stopped while slowing down.
[0045]
(Judgment of ground cutting)
Next, with reference to FIGS. 8 and 9, the ground cutting determination device C and the ground cutting determination method of this embodiment will be described in detail. The ground cutting determination device C includes a boom 14, a winch 13, a load measuring means 22, a rope length and hoisting speed measuring means 24, and a controller 40 as a control unit for controlling the boom 14 and the winch 13. Will be done.
[0046]
Then, in the ground cutting control, the controller 40 of the present embodiment cuts the ground based on the time change of the measured load and the time change of the measured rope length when the winch 13 is wound up and the suspended load is grounded. Is designed to be determined.
[0047]
Specifically, the controller 40 as a control unit sets the rope length at the time when the measured load starts to change when the winch 13 is wound up and cuts the suspended load, and the rope length is set to the rope length. When it becomes shorter than the threshold value set from the initial rope length, it is determined that the ground has been cut.
[0048]
Alternatively, the controller 40 as a control unit sets the time change of the rope length at the time when the measured load starts to change when the winch 13 is wound up and cuts the suspended load as the initial winding speed, and the time of the rope length is set. When the winding speed, which is a change, becomes faster than the threshold set from the initial winding speed, it is determined that the ground has been cut.
[0049]
That is, as shown in FIG. 8A, at the start of ground cutting, the wire rope 16 is loose even when the winch 13 is wound up, so that almost no load is applied, and when the winch 13 is wound up as it is, the wire rope 16 and the hook 17 are used. The weight of the rope will work. After that, when the winch 13 is further wound up, the load increases (changes) while causing the boom 14 to bend, as shown in FIG. 8 (b). Then, when the load changes beyond a predetermined threshold value, the rope length is initialized. After that, when the winch 13 is further wound up, as shown in FIG. 8 (c), the rope length suddenly shortens after the maximum bending occurs in the boom 14. Then, the time when the rope length suddenly changes can be grasped and determined as the ground cutting time.
[0050]
Alternatively, when the load changes beyond a predetermined threshold value, the time change of the rope length, that is, the winding speed is initialized. After that, when the winch 13 is further wound up, as shown in FIG. 8C, the winding speed suddenly increases after the maximum bending occurs in the boom 14. Then, the time when the winding speed suddenly changes can be grasped and determined as the ground cutting time.
[0051]
That is, in the ground cutting determination method of this embodiment, the step of winding the winch 13, the step of measuring the load, the step of measuring the rope length of the wire rope 16, and the rope length at the time when the load starts to change are set. It is composed of a step of storing as the initial rope length and a step of determining that the ground has been cut when the rope length becomes shorter than the threshold set from the initial rope length.
[0052]
Alternatively, in the ground cutting determination method of this embodiment, the step of winding the winch 13, the step of measuring the load, the step of measuring the winding speed of the wire rope 16, and the winding speed at the time when the load starts to change are determined. It is composed of a step of storing as an initial winding speed and a step of determining that the ground is cut when the winding speed becomes faster than the threshold set from the initial winding speed.
[0053]
Hereinafter, the ground cutting determination method will be described using the flowchart of FIG. Here, only the ground cutting determination method will be described using the flowchart of FIG. The whole of the ground cutting control method is as described with reference to FIG. 7. That is, here, in the flowchart of FIG. 7, the content of the ground cutting determination in step S5 will be described.
[0054]
As shown in the flowchart of FIG. 9, this ground cutting determination method includes a process of capturing a change in the load in the first half (steps S51 to S52) and a process of capturing a change in the rope length (or hoisting speed) in the second half (steps S51 to S52). It is divided into steps S53 to S55). In the following, for convenience of explanation, it is assumed that the load is measured in step S51.
[0055]
In the first half, first, the load is measured by the load measuring means 22, and the time series data of the load is monitored by the controller 40 (step S51). Then, if the load changes beyond the threshold value (YES in step S52), the controller 40 initializes the rope length (step S53). That is, the rope length R0 at the time when the threshold value is exceeded is stored. On the other hand, if the load does not change beyond the threshold value (NO in step S52), the controller 40 continues to measure the load (steps S51 to S52).
[0056]
In the latter half, the rope length is first measured by the rope length and hoisting speed measuring means 24, and the time series data of the rope length is monitored by the controller 40 (step S54). Then, if the rope length is shorter than the initial rope length R0 by more than the threshold value (YES in step S55), the controller 40 determines that the ground has been cut (step S56). On the other hand, if the rope length is not shorter than the initial rope length R0 by more than the threshold value (NO in step S55), the controller 40 continues to measure the rope length (steps S54 to S55).
[0057]
Alternatively, although not shown, the controller 40 determines that the rope has been cut off if the time change of the rope length-that is, the winding speed-is faster than the initial winding speed V0 by exceeding the threshold value (corresponding to YES in step S55). (Corresponding to step S56). On the other hand, if the winding speed does not exceed the threshold value from the initial winding speed V0 (corresponding to NO in step S55), the controller 40 continues to measure the rope length (winding speed) (corresponding to steps S54 to S55). ).
[0058]
In this way, the ground cutting is determined by the process / judgment of capturing the change in the load (steps S51 to S52) and the process / determination of capturing the change in the rope length (or hoisting speed) (S53 to S55).
[0059]
(effect)
Next, the effects of the ground cutting determination device C, the ground cutting control device D, and the rough terrain crane 1 as a mobile crane of this embodiment will be listed and described.
[0060]
(1) As described above, in the ground cutting determination device C of the present embodiment, the boom 14 configured to be undulating, the winch 13 for hoisting / unwinding the suspended load via the wire rope 16, and the boom 14 A load measuring means 22 for measuring the load acting on the wire rope 16, a rope length and hoisting speed measuring means 24 for measuring the rope length of the wire rope 16, and a controller 40 for controlling the boom 14 and the winch 13. It is equipped with a controller 40 that determines the ground cutting based on the time change of the measured load and the time change of the measured rope length when hoisting and cutting the suspended load. ing. With such a configuration, it is possible to quickly determine the ground cutting by a simple method while suppressing load shake.
[0061]
That is, due to the characteristics of the load measuring means 22, there is a slight time difference between capturing the change in load and actually cutting the ground. During this time, monitoring of the ground cutting is started, and the ground cutting itself is a responsive rope. It is captured by the length and hoisting speed measuring means 24. As a result, the ground cutting determination device C having good responsiveness is obtained by a simple configuration. Further, it can be used for setting the coordinates of the route control based on the relationship between the rope length and the height of the suspended load.
[0062]
(2) Specifically, the controller 40 sets the rope length at the time when the measured load starts to change when the winch 13 is wound up and cuts the suspended load, and the rope length is set to the initial rope length R0. When the initial rope length R0 becomes shorter than the set threshold value, it is determined that the ground has been cut.
[0 063]
(3) Alternatively, when the winch 13 is wound up and the suspended load is grounded, the controller 40 sets the time change of the rope length at the time when the measured load starts to change as the initial winding speed V0, and sets the time of the rope length. When the winding speed, which is a change, becomes faster than the threshold value set from the initial winding speed V0, it is determined that the ground has been cut.
[0064]
(4) Further, the ground cutting control device D of the present embodiment is a boom 14, a winch 13, a load measuring means 22, and a controller 40 as a control unit for controlling the boom 14 and the winch 13, and is a winch 13. The controller 40, which obtains the amount of change in the undulation angle of the boom 14 based on the time change of the measured load when hoisting and cutting the suspended load, and undulates the boom 14 so as to compensate for the change. I have. With such a configuration, the ground cutting control device D can quickly cut the suspended load while suppressing the load runout.
[0065]
That is, in the ground cutting control device D of the present embodiment, attention is paid to the linear relationship between the load and the undulation angle, and the feedforward control is performed based only on the time change of the load value, as in the conventional case. Suspended loads can be quickly grounded without the need for complicated feedback control.
[0066]
(5) Further, the posture measuring means 23 for measuring the posture of the boom 14 is further provided, and the controller 40 responds based on the measured initial value of the posture of the boom 14 and the measured initial value of the load. It is preferable to select a characteristic table or transfer function and use the characteristic table or transfer function to obtain the amount of change in the undulation angle of the boom 14 from the time change of the measured load.
[0067]
With this configuration, at the start of ground cutting control, the winch 13 is wound at a constant speed, the undulation angle control amount is calculated from the characteristic table (or transfer function) according to the load change, and feedforward control is performed. Therefore, it is possible to quickly cut the ground without shaking. In addition, by reducing the number of parameters to be adjusted, factory adjustment can be performed quickly and easily.
[0068]
(6) Further, it is preferable that the controller 40 is configured to wind the winch 13 at a constant speed when the winch 13 is wound up and the suspended load is grounded. With this configuration, it is possible to facilitate the ground cutting determination by suppressing the influence of disturbance such as inertial force and stabilizing the response (measured load value).
[0069]
(7) Further, the rough terrain crane 1, which is the mobile crane of the present embodiment, is provided with any of the above-mentioned ground cutting determination device C or ground cutting control device D, so that the load can be swung quickly. It is a rough terrain crane 1 that can cut the suspended load.
[0070]
(8) Further, the ground cutting determination method of the present embodiment includes a step of winding the winch 13, a step of measuring the load, a step of measuring the rope length of the wire rope 16, and a time when the load starts to change. It is composed of a step of storing the rope length as the initial rope length R0 and a step of determining that the ground has been cut when the rope length becomes shorter than the threshold set from the initial rope length R0. Therefore, it is possible to quickly determine the ground cutting by a simple method while suppressing the load shake.
[0071]
(9) Further, another ground cutting method of this embodiment is a step of winding the winch 13, a step of measuring the load, a step of measuring the winding speed of the wire rope 16, and a time when the load starts to change. It is composed of a step of storing the winding speed as the initial winding speed V0 and a step of determining that the ground is cut when the winding speed becomes faster than the threshold value set from the initial winding speed V0. Therefore, it is possible to quickly determine the ground cutting by a simple method while suppressing the load shake.
[0072]
Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes to the extent that the gist of the present invention is not deviated are made in the present invention. included.
[0073]
For example, although not particularly described in the examples, the ground cutting control device D of the present invention is applied regardless of whether the ground cutting is performed using the main winch as the winch 13 or the ground cutting using the sub winch. be able to.
Description of the sign
[0074]
C: Ground cutting determination device; D: Ground cutting control device; a: Linear coefficient;
1: Rough terrain crane; 10: Body; 12: Swing platform;
13: Winch; 14: Boom; 16: Wire; 17: Hook;
20: Ground cutting switch;
21: Winch speed setting means;
22: Pressure gauge (load measuring means);
23: Ups and downs angle meter (posture detection means);
24: Rope length and hoisting speed length measuring means;
40: Controller;
40a: Selection function unit; 40b: Ground cutting determination function unit;
51: Swing lever; 52: Undulating lever;
53: Telescopic lever; 54: Winch lever;
61: Swing motor; 62: Undulating cylinder;
63: Telescopic cylinder; 64: Winch motor
The scope of the claims
[Claim 1]
A boom that can be undulated and
A winch that winds up / unwinds a suspended load via a wire rope,
A load measuring means for measuring the load acting on the boom,
Rope length measuring means for measuring the rope length of the wire rope,
It is a control unit that controls the boom and the winch, and is based on the time change of the measured load and the time change of the measured rope length when the winch is wound up and the suspended load is grounded. The control unit, which is designed to determine the ground cutting,
A ground cutting determination device.
[Claim 2]
The control unit sets the rope length as the initial rope length at the time when the measured load starts to change when the winch is wound up and the suspended load is grounded, and the rope length is set from the initial rope length. The ground cutting determination device according to claim 1, wherein when the time becomes shorter than the threshold value, it is determined that the ground has been cut.
[Claim 3]
When the winch is wound up and the suspended load is grounded, the control unit sets the time change of the rope length at the time when the measured load starts to change as the initial hoisting speed, and is the time change of the rope length. The ground cutting determination device according to claim 1, wherein when the winding speed becomes faster than a threshold value set from the initial winding speed, it is determined that the ground has been cut.
[Claim 4]
A ground cutting control device including the ground cutting determination device according to any one of claims 1 to 3.
When the winch is wound up and the suspended load is grounded, the control unit obtains the amount of change in the undulation angle of the boom based on the time change of the measured load, and the boom is compensated for the amount of change. A ground cutting control device that is designed to undulate.
[Claim 5]
Further equipped with a posture measuring means for measuring the posture of the boom,
The control unit selects a corresponding characteristic table or transfer function based on the measured initial value of the boom posture and the measured initial value of the load, and uses the characteristic table or transfer function. The ground cutting control device according to claim 4, wherein the amount of change in the undulation angle of the boom is obtained from the time change of the measured load.
[Claim 6]
The ground cutting control device according to claim 4 or 5, wherein the control unit winds up the winch at a constant speed when hoisting the winch to ground the suspended load.
[Claim 7]
A mobile crane provided with the ground cutting determination device according to any one of claims 1 to 3.
[Claim 8]
A mobile crane provided with the ground cutting control device according to any one of claims 4 to 6.
[Claim 9]
It is a ground cutting judgment method,
The step of winding the winch and
The step to measure the load and
The step of measuring the rope length of the wire rope and
The step of memorizing the rope length at the time when the load started to change as the initial rope length,
A ground cutting determination method including a step of determining that the ground has been cut when the rope length becomes shorter than the threshold value set from the initial rope length.
[Claim 10]
It is a ground cutting judgment method,
The step of winding the winch and
The step to measure the load and
The step to measure the winding speed of the wire rope and
A step to memorize the winding speed at the time when the load starts to change as the initial winding speed,
A ground cutting determination method including a step of determining ground cutting when the winding speed becomes faster than a threshold value set from the initial winding speed.