JP2021146440A - Control device and control method - Google Patents

Abstract

To enable the life of an internal mechanism provided in a shaft of a robot arm to extend.SOLUTION: A control device includes a movement information setting part 11 for setting information about movement of a robot arm having a plurality of shafts, a life determination part 13 for detecting an internal cable having short life among internal cables provided in the shafts of the robot arm, and a track setting part 14 for generating a track such that the internal cables provided in the shafts of the robot arm have equal life on the basis of the information set by the movement information setting part 11 and a determination result by the life determination part 13.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control device and a control method for controlling the trajectory of a robot arm.

In a robot arm (multi-axis robot arm) having a plurality of axes (joints), an internal cable is provided on the axis (see, for example, Patent Document 1). Examples of the internal cable include a power supply line for supplying electric power to a motor provided on the shaft, a signal line for inputting / outputting signals, and the like.

A load (pulling and twisting force) is applied to this internal cable by the rotation of the shaft. On the other hand, since the operation of the robot arm differs for each application, the number of times the shaft is driven and the amount of rotation differ for each shaft. Therefore, depending on how the robot arm operates, it is conceivable that the load will be concentrated only on the internal cable provided on a specific shaft. If the load is concentrated only on the internal cable provided on the specific shaft, the life of the internal cable becomes shorter than the life of the internal cable provided on the other shaft, and the wire is easily broken.

Patent No. 5670588

As described above, in the conventional robot arm, the load is concentrated only on the internal cable provided on a specific shaft, the life of the internal cable is shortened, and the wire may be easily broken. On the other hand, disconnection of the internal cable can be a big problem when the robot arm is used in the field such as a factory. That is, if the internal cable is broken, the production line at the site is stopped, and it takes time and effort to replace the internal cable. In particular, replacement of the internal cable requires disassembly of the robot arm housing and the like, so it takes time to recover.
The above-mentioned problems are not limited to the internal cable, but also exist for other internal mechanisms provided on the shaft.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a control device capable of extending the life of an internal mechanism provided on a shaft of a robot arm.

The control device according to the present invention detects a movement information setting unit that sets information regarding the movement of a robot arm having a plurality of axes, and an internal mechanism having a short life among the internal mechanisms provided on the axes of the robot arm. Track setting that sets a trajectory that equalizes the life of the internal mechanism provided on the shaft of the robot arm based on the information set by the life determination unit, the movement information setting unit, and the judgment result by the life determination unit. It is characterized by having a part.

According to the present invention, since it is configured as described above, it is possible to extend the life of the internal mechanism provided on the shaft of the robot arm.

It is a figure which shows the structural example of the control device which concerns on Embodiment 1. FIG. It is a flowchart which shows the operation example of the control device which concerns on Embodiment 1. FIG. 3A and 3B are diagrams showing an operation example of the control device according to the first embodiment. It is a figure which shows the structural example of the control device which concerns on Embodiment 2.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1.
FIG. 1 is a diagram showing a configuration example of the control device 1 according to the first embodiment. In FIG. 1, in addition to the control device 1, a measurement unit 2 and a motor control unit 3 provided for each axis of the robot arm, which will be described later, are also shown.

The robot arm is a robot arm (multi-axis robot arm) having a plurality of axes (joints). The robot arm is provided with an internal mechanism (not shown) on the shaft. Examples of the internal mechanism include an internal cable, a motor, a gear, and the like. The following shows a case where the internal mechanism for determining the life of the control device 1 is an internal cable. A load (pulling and twisting force) is applied to the internal cable by the rotation of the shaft. Further, the robot arm is provided with a measurement unit 2 and a motor control unit 3 for each axis. FIG. 1 shows a case where the robot arm has N axes.

The measuring unit 2 measures at least one of the parameters indicating the operating conditions of the shaft to be measured. Parameters indicating the operating conditions of the shaft include the number of rotations, the amount of rotation, the speed, the acceleration, and the like of the shaft.
The motor control unit 3 controls the motor based on the data indicating the trajectory output by the control device 1. The motor is driven according to the control by the motor control unit 3 to move the shaft provided with the motor.

The control device 1 controls the trajectory of the robot arm. That is, the control device 1 sets the trajectory of the robot arm and outputs data indicating the trajectory to each motor control unit 3. As shown in FIG. 1, the control device 1 includes a movement information setting unit 11, a life estimation unit 12, a life determination unit 13, a trajectory setting unit 14, and an output unit 15.

The control device 1 is realized by a processing circuit such as a system LSI (Large Scale Integration), a CPU (Central Processing Unit) that executes a program stored in a memory or the like, or the like.

The movement information setting unit 11 sets information related to the movement of the robot arm. At this time, the movement information setting unit 11 sets a plurality of patterns of trajectories for each application, for example, as information related to movement.

The life estimation unit 12 estimates the life of the internal cable provided on the shaft for each shaft of the robot arm. At this time, the life estimation unit 12 estimates the life of the internal cable by integrating the parameters measured by the measurement unit 2 for each axis of the robot arm and calculating the cumulative value of the load on the internal cable. do.

The life determination unit 13 detects an internal cable having a short life among the internal cables provided on the shaft of the robot arm. In the first embodiment, the life determination unit 13 detects an internal cable having a short life (a large cumulative value of the load) based on the life (cumulative value of the load) estimated by the life estimation unit 12.

The trajectory setting unit 14 sets a trajectory so that the life of the internal cable provided on the shaft of the robot arm is equalized based on the information set by the movement information setting unit 11 and the determination result by the life determination unit 13. do.

The output unit 15 outputs data indicating the trajectory set by the track setting unit 14 to each motor control unit 3.

Next, an operation example of the control device 1 according to the first embodiment shown in FIG. 1 will be described with reference to FIG. The measuring unit 2 measures at least one of the parameters indicating the operating conditions of the shaft to be measured.
In the operation example of the control device 1 according to the first embodiment shown in FIG. 1, as shown in FIG. 2, the movement information setting unit 11 first sets information regarding the movement of the robot arm (step ST201). At this time, the movement information setting unit 11 sets a plurality of patterns of trajectories for each application, for example, as information related to movement. The trajectories of the plurality of patterns are set so that the operating conditions of each axis of the robot arm are as different as possible, and the load is not concentrated only on the internal cable provided on the specific axis. desirable. Further, the above-mentioned plurality of patterns of orbits are orbits in which the robot arm does not come into contact with surrounding obstacles.

Next, the life estimation unit 12 estimates the life of the internal cable provided on the shaft for each shaft of the robot arm (step ST202). At this time, the life estimation unit 12 estimates the life of the internal cable by integrating the parameters measured by the measurement unit 2 for each axis of the robot arm and calculating the cumulative value of the load on the internal cable. do.

In the robot arm, the length of each shaft is different, and it is assumed that the method of routing the internal cable differs depending on the shaft. Therefore, even under the same operating conditions, it is assumed that the life of the internal cable may differ for each axis depending on the housing structure of the robot arm. Therefore, the life estimation unit 12 may estimate the life of the internal cable by adding a weighting coefficient according to the housing structure (shaft length, routing method, etc.) of the robot arm.

Next, the life determination unit 13 detects an internal cable having a short life (a large cumulative value of the load) based on the life (cumulative value of the load) estimated by the life estimation unit 12 (step ST203). Here, for example, the life determination unit 13 sets in advance the maximum cumulative value of the load on the internal cables provided on each shaft of the robot arm. The maximum cumulative load value is the maximum allowable load cumulative value for the internal cable. The cumulative maximum value of this load is set based on, for example, the operating conditions of the shaft provided with the internal cable or the housing structure of the robot arm. Then, the life determination unit 13 compares the cumulative value of the load calculated by the life estimation unit 12 with the maximum cumulative value of the load, and the cumulative value of the load is within the threshold value with respect to the maximum cumulative value of the load. Detect an internal cable as a short-lived internal cable.

The life determination method by the life determination unit 13 is not limited to the above method. For example, the life determination unit 13 may simply detect the internal cable having the shortest life among the internal cables, or may detect a predetermined number of internal cables in the order of the shortest life.

Next, the trajectory setting unit 14 is a trajectory that equalizes the life of the internal cable provided on the shaft of the robot arm based on the information set by the movement information setting unit 11 and the determination result by the life determination unit 13. Is set (step ST204). Here, when the orbit setting unit 14 sets a plurality of patterns of orbits for each application by the movement information setting unit 11, the life determination unit 13 determines that the life is short among the orbits of the plurality of patterns of the corresponding application. The trajectory is set by selecting a trajectory that does not move the shaft on which the internal cable is provided as much as possible.

Next, the output unit 15 outputs data indicating the trajectory set by the track setting unit 14 to each motor control unit 3 (step ST205). After that, the motor control unit 3 controls the motor based on the trajectory set by the control device 1, and the motor is driven according to the control by the motor control unit 3.

In the above, the movement information setting unit 11 sets a plurality of patterns of orbits for each application, and the orbit setting unit 14 selects an orbit from the plurality of patterns of orbits according to the determination result by the life determination unit 13. Indicated. However, the present invention is not limited to this, for example, the movement information setting unit 11 sets the start point and the end point of the hand of the robot arm or the trajectory of the hand of the robot arm as information regarding movement, and the trajectory setting unit 14 sets the trajectory of the hand. The trajectory may be set by generating an appropriate trajectory according to the information regarding the movement and the determination result by the life determination unit 13.

In this way, in the control device 1 according to the first embodiment, the life of the internal cable is estimated (calculated the cumulative value of the load) for each axis of the robot arm, and a trajectory is set so that the life is even. do. That is, in this control device 1, when it is determined that the load is concentrated on the internal cable provided on a specific axis, a trajectory is set so that the axis is not moved as much as possible in the next operation. As a result, in the control device 1, the life of the internal cable provided on the shaft of the robot arm can be equalized, and the life until the internal cable is broken can be extended.

Next, a specific example of the operation of the control device 1 according to the first embodiment will be described.
First, consider the case where the hand of the robot arm moves from an arbitrary point (start point) to a point (end point) with reference to FIG. In FIG. 3, reference numeral 301 indicates a robot arm.
In this case, as shown in FIG. 3, the position and orientation of the hand of the robot arm are fixed at the start point (point A) and the end point (point B). On the other hand, there are multiple options for the trajectory of the robot arm. Therefore, a trajectory that does not move only a specific axis among the axes of the robot arm can be considered.
Here, as shown in FIG. 3A, the trajectory from the point A to the point B is a trajectory connecting the points A and B with a straight line when moving at the shortest distance. In this case, the movement of the axis closest to the hand of the robot arm becomes large. On the other hand, when the load is concentrated on the internal cable connected to the specific shaft by the operation so far, the control device 1 changes the trajectory so that the shaft does not move. For example, when the control device 1 determines that the cumulative value of the load of the internal cable connected to the axis closest to the hand of the robot arm is large, the control device 1 changes from the trajectory shown in FIG. 3A to the trajectory shown in FIG. 3B. , Suppress the load applied to the internal cable.

Next, consider the case where the hand of the robot arm moves on an arbitrary orbit.
In this case, when the robot arm has six axes, a plurality of postures of the robot arm are determined. However, when the hand of the robot arm moves on an arbitrary trajectory, there is a trajectory that cannot be realized by the configuration of six axes. On the other hand, when the robot arm has a redundant configuration having seven or more axes, it can move on an arbitrary orbit. For example, as an application utilizing the force control assumed by the robot arm, there is polishing of parts. In this polishing, the robot arm needs to move on a specific trajectory while maintaining a determined position and orientation to press a hand-mounted tool against the surface of the component with a constant force. Here, as described above, when the robot arm has seven or more axes, the same work can be realized even if the parts other than the hand of the robot arm are in different postures. Therefore, the control device 1 is in a posture in which the axis other than the axis closest to the hand of the robot arm is not moved as much as possible in the axis in which the load is concentrated in the operation so far.

As described above, according to the first embodiment, the control device 1 has a movement information setting unit 11 for setting information regarding the movement of the robot arm having a plurality of axes, and an internal portion provided on the shaft of the robot arm. Of the cables, the inside provided on the shaft of the robot arm is based on the life determination unit 13 that detects the internal cable having a short life, the information set by the movement information setting unit 11, and the determination result by the life determination unit 13. A track setting unit 14 for setting a track so that the life of the cable is even is provided. As a result, the control device 1 according to the first embodiment can extend the life of the internal cable provided on the shaft of the robot arm.

In the first embodiment, the case where the internal mechanism for determining the life of the control device 1 is an internal cable is shown. However, the internal mechanism is not limited to this, and the internal mechanism may be another internal mechanism (motor, gear, etc.).
In this case, the measuring unit 2 measures at least one of parameters such as voltage, current, temperature, and vibration with respect to the internal mechanism. Then, the life estimation unit 12 monitors the parameters measured by the measurement unit 2 for each axis of the robot arm, and estimates the life of the internal mechanism from the change of the parameters.

Embodiment 2.
FIG. 4 is a diagram showing a configuration example of the control device 1 according to the second embodiment. The control device 1 according to the second embodiment shown in FIG. 4 changes the life estimation unit 12 to the disconnection sign detection unit 16 with respect to the control device 1 according to the first embodiment shown in FIG. Other configurations are the same as those of the control device 1 according to the first embodiment, and only the different parts will be described.

The disconnection sign detection unit 16 detects a disconnection sign of the internal cable. At this time, for example, the measuring unit 2 measures the resistance value of the internal cable, the disconnection sign detection unit 16 monitors the resistance value measured by the measuring unit 2, and the change in the resistance value is a sign of the disconnection of the internal cable. May be detected. Further, for example, cables configured to be more easily broken than the internal cable are arranged side by side with respect to the internal cable, and the disconnection sign detection unit 16 detects the disconnection of the cable to predict the disconnection of the internal cable. May be detected.

The lifespan determination unit 13 detects an internal cable in which a sign of disconnection is detected by the disconnection sign detection unit 16 as an internal cable having a short lifespan.

As described above, in the control device 1 according to the second embodiment, the sign of the disconnection of the internal cable is detected in advance, and the trajectory provided with the internal cable for which the sign of the disconnection is detected is set so as not to move as much as possible. do. As a result, in this control device 1, in addition to the effect in the first embodiment, it is possible to gain time until the internal cable is completely disconnected. Therefore, the operator can easily replace the internal cable at the right time.

In the first embodiment, the lifespan determination unit 13 determines the lifespan based on the estimation result by the lifespan estimation unit 12, and in the second embodiment, the lifespan determination unit 13 determines the lifespan based on the detection result by the disconnection sign detection unit 16. Was shown. However, the life is not limited to this, and the life determination unit 13 may perform the life determination based on both the estimation result by the life estimation unit 12 and the detection result by the disconnection sign detection unit 16. This is considered to improve the accuracy of estimating the life of the internal cable.

In the present invention, within the scope of the invention, it is possible to freely combine each embodiment, modify any component of each embodiment, or omit any component in each embodiment. be.

1 Control device 2 Measuring unit 3 Motor control unit 11 Movement information setting unit 12 Life estimation unit 13 Life judgment unit 14 Track setting unit 15 Output unit 16 Disconnection sign detection unit

Claims (5)

A movement information setting unit that sets information related to the movement of a robot arm having multiple axes,
Among the internal mechanisms provided on the shaft of the robot arm, a life determination unit that detects an internal mechanism having a short life, and a life determination unit.
Based on the information set by the movement information setting unit and the determination result by the life determination unit, the trajectory setting unit sets the trajectory so that the life of the internal mechanism provided on the shaft of the robot arm becomes equal. Control device equipped with. For each axis of the robot arm, a life estimation unit for estimating the life of the internal mechanism provided on the axis is provided.
The control device according to claim 1, wherein the life determination unit detects an internal mechanism having a short life based on the life estimated by the life estimation unit. The internal mechanism is an internal cable.
The life estimation unit integrates at least one of the parameters indicating the operating conditions of the shaft for each shaft of the robot arm, and calculates the cumulative value of the load on the internal cable. The control device according to claim 2, wherein the life of the cable is estimated. The internal mechanism is an internal cable.
It is equipped with a disconnection sign detection unit that detects the precursor of disconnection of the internal cable.
Any one of claims 1 to 3, wherein the life determination unit detects an internal cable in which a sign of disconnection is detected by the disconnection sign detection unit as an internal cable having a short life. The control device described. A step in which the movement information setting unit sets information regarding the movement of a robot arm having a plurality of axes,
A step in which the life determination unit detects an internal mechanism having a short life among the internal mechanisms provided on the shaft of the robot arm.
The trajectory setting unit sets a trajectory so that the life of the internal mechanism provided on the shaft of the robot arm is equalized based on the information set by the movement information setting unit and the determination result by the life determination unit. A control method that has steps to do.

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