CN105983966B

CN105983966B - Control device and method for robot arm

Info

Publication number: CN105983966B
Application number: CN201510078209.4A
Authority: CN
Inventors: 苏怡宾; 吴仁琛
Original assignee: Techman Robot Inc
Current assignee: Techman Robot Inc
Priority date: 2015-02-13
Filing date: 2015-02-13
Publication date: 2020-06-12
Anticipated expiration: 2035-02-13
Also published as: CN105983966A

Abstract

The invention discloses a control device and a method of a robot arm, which are used for teaching a working path of the robot arm, setting a total power limit of all actuating shafts, recording the rotating power of each actuating shaft when trying on the taught working path, calculating the accumulated total power of each actuating shaft at regular time, and regulating and reducing the rotating power of each actuating shaft when checking that the accumulated total power exceeds the total power limit so that the accumulated total power is not more than the total power limit to accelerate teaching work.

Description

Control device and method for robot arm

Technical Field

The present invention relates to a robot arm, and more particularly, to a control device and method for preventing the robot arm from exceeding a moving speed limit in a teaching operation path.

Background

Although the robot arm has the characteristic of flexible and fast movement, inertia generated by movement beyond a speed limit can not only make the robot arm unable to accurately position, but also damage the structure of the robot arm, especially the fast-moving robot arm, and also hurt or threaten the safety of surrounding workers.

As shown in fig. 4, a prior art robot arm 1 is shown. In the prior art robot arm 1, a first actuating shaft 3 is provided on a base 2 to drive a first arm 4, a second actuating shaft 5 is provided on the first arm 4 to drive a second arm 6, and a third actuating shaft 7 is provided on the second arm 6 to drive a tip 8. The robot arm 1 controls the rotation angle of each actuating shaft to move the end portion 8 to a desired position to pick and place an object. Since the shape and length of each arm of the robot arm 1 are fixed, and the distances between the position on each arm and the rotating shafts A, B and C that drive the actuating axes of each arm can be measured, the moving speed of each point on the robot arm 1 can be calculated by acquiring the rotational speed of each actuating axis of the robot arm 1.

Since the specific point (singular) with the fastest moving speed of the robot arm is usually located at the periphery of the robot arm, the robot arm 1 in the prior art selects several peripheral positions, such as the rotating shaft B of the second actuating shaft 5, the rotating shaft C of the third actuating shaft 7, the outer end point D of the second arm 6, and the end point E of the end portion 8, as monitoring points of the robot arm 1 according to the features of the shape, and monitors the moving speeds of the rotating shaft B to the rotating shaft B ', the rotating shaft C to the rotating shaft C', the end point E to the end point E ', and the outer end point D to the outer end point D' at any time during the moving process of the robot arm 1, so as to prevent the moving speed limit from being exceeded, and maintain the safety of the peripheral operations of the robot arm 1.

The prior art teaches that when the robot arm 1 moves to pick and place objects, the shortest path and the optimal speed are usually planned and set, so that the end portion 8 of the robot arm 1 can quickly reach the location with the optimized moving line to complete the work, and therefore, the moving speed of the robot arm 1 changes along with the taught work path. After the teaching is completed, the working path to be subjected to trial teaching is moved, for example, from the robot arm 1 in the solid line position to the robot arm 1' in the broken line position in the figure. In order to maintain the safety of peripheral operators and the like, the speed limit of each monitoring point of the robot arm 1 needs to be set before trial. And then, performing a trial, wherein the robot arm 1 monitors the moving speed of the monitoring point, and if the monitoring point does not move beyond the speed limit from the rotating shaft B to the rotating shaft B ', from the rotating shaft C to the rotating shaft C ', from the end point E to the end point E ' and from the end point D to the outer end point D ', the end point E of the end point portion 8 smoothly moves to the end point E ' according to the set optimized path 9 and speed.

On the contrary, in the trial run, once the robot arm 1 moves beyond the speed limit at a monitoring point, the robot arm 1 in the prior art will immediately stop moving to maintain the safety of the operation, wait for the operator to re-plan the movement speed of each arm or adjust the speed limit, and restart the robot arm to continue the trial run. Therefore, the setting is often required to be modified for many times, so that the teaching operation of the robot arm can be completed in a time-consuming manner, and the robot arm can safely perform the production operation. Therefore, in the prior art, the maximum moving speed of the monitored point monitored by the robot arm 1 is selected, and when the moving speed exceeds the set speed limit, the moving speed of the monitored point is automatically reduced to be lower than the set speed limit, and then the trial is continued.

However, in the prior art, when the monitoring point exceeds the moving speed limit, the adjustment and decrease of the moving speed of a single monitoring point will change the endpoint E of the robot arm to the moving path 10, which results in deviation from the optimized teaching moving path and speed, increase of the working time of the robot arm, and decrease of the production efficiency of the robot arm. In addition, in the prior art, the robot arm selects the monitoring points, the moving speed of each monitoring point on the robot arm needs to be calculated one by one, the monitoring mode is complex, and the robot arm with overlapped multiple shafts is particularly difficult. Therefore, there is still a need to solve the problem of the robot arm in the speed limit control method.

Disclosure of Invention

The invention aims to provide a control device and a control method for a machine arm, which control the rotation power of an actuating shaft by setting the total power limit of all actuating shafts, limit the moving speed of each arm and simplify the trial operation.

Another objective of the present invention is to provide a control apparatus and method for a robot arm, which compares that the total accumulated power of each actuation axis exceeds a set total power limit, and reduces the rotation power of each actuation axis proportionally to maintain an optimized operation path and speed.

Still another objective of the present invention is to provide a control apparatus and method for a robot arm, which utilizes the ratio of the total power limit to the accumulated total power to adjust and reduce the rotation power of each actuation axis to accelerate the completion of teaching operation.

In order to achieve the above-mentioned object, the control device for a robot arm of the present invention utilizes a total power setting unit to provide a total power limit for setting the rotation power of the actuating shaft, a power monitoring unit to record and monitor the rotation power of the actuating shaft, a power comparing unit to sum the rotation power of the actuating shaft at regular time to form a cumulative total power, and compare the cumulative total power with the set total power limit G, to check whether the accumulated total power exceeds a total power limit, the power regulating unit calculates a ratio of the total power limit to the accumulated total power when the accumulated total power exceeds the total power limit, and the driving unit receives a signal of the power adjusting unit for adjusting the rotating power of the actuating shaft and controls the actuating shaft to rotate with the adjusted rotating power.

The control method of the robot arm comprises the steps of setting a total power limit of all actuating shafts when teaching a working path of the robot arm, then trying the taught working path, recording the rotating power of each actuating shaft, calculating and adding the rotating power of each actuating shaft in a timing mode to form an accumulated total power, checking that the accumulated total power exceeds the total power limit, calculating the proportion of the total power limit to the accumulated total power, and reducing the rotating power of each actuating shaft in an equal proportion according to the proportion of the total power limit to the accumulated total power or not less than the proportion so that the accumulated total power is not more than the total power limit, thereby finishing the operation path tried and taught.

Drawings

FIG. 1 is a schematic control diagram of a robot arm according to the present invention;

FIG. 2 is a schematic diagram of the rotational power of the robot arm of the present invention;

FIG. 3 is a flowchart of a control method of the robot arm according to the present invention;

fig. 4 is a schematic diagram of the movement of a prior art robot arm.

Description of the symbols

20 robot arm

21 base

22 first arm

23 second arm

24 end portion

30 control device

31 total power setting unit

32 power monitoring unit

33 power comparison unit

34 power regulating unit

35 drive unit

K, L, M actuating shaft

Detailed Description

The technical means and effects of the present invention for achieving the above objects will be described below with reference to the accompanying drawings.

Referring to fig. 1 and fig. 2, fig. 1 is a control schematic diagram of the robot arm of the present invention, and fig. 2 is a schematic diagram of the rotation power of the robot arm of the present invention. The movement of the robot arm 20 of the present invention is mainly controlled by the control device 30. Wherein the robot arm 20 is provided with a first actuating shaft K on the base 21 for rotating the first arm 22, a second actuating shaft L on the first arm 22 for rotating the second arm 23, and a third actuating shaft M on the second arm 22 for rotating the end portion 24. Although a three-axis robot is illustrated in the present embodiment, the present invention is applicable to a multi-axis robot including at least one actuating axis.

The control device 30 of the present invention is used for controlling the rotation of each actuating shaft, and mainly includes a total power setting unit 31, a power monitoring unit 32, a power comparing unit 33, a power adjusting unit 34, a driving unit 35, and the like. Wherein the total power setting unit 31 provides the user to set the total power limit G of all the actuating shafts to limit the rotating power of each actuating shaft. The power monitoring unit 32 instantaneously records and monitors the rotational power of each actuation shaft. The power comparing unit 33 records the rotation power of each actuation axis according to the power monitoring unit 32, periodically sums the rotation power of each actuation axis to form a cumulative total power T, and compares the cumulative total power T with the total power limit G set by the total power setting unit 31 to check whether the cumulative total power T exceeds the total power limit G, so as to determine whether the robot arm 20 moves beyond the speed limit. When the accumulated total power T exceeds the total power limit G, the power adjusting unit 34 calculates a ratio P between the total power limit G and the accumulated total power T, and proportionally reduces the rotating power of each actuating shaft, so that the reduced accumulated total power T' is not greater than the total power limit G. The driving unit 35 receives the signal of the power adjusting unit 34 for reducing the rotation power of each actuating shaft, and controls each actuating shaft to rotate with the reduced rotation power.

Since the first arm 22 of the robot arm 20 of the present invention is rotated by the first actuating shaft K, the moving speed of the first arm 22 is determined by the rotating speed of the first actuating shaft K, and the rotating speed of the first actuating shaft K is determined by the rotating power output by the first actuating shaft K controlled by the driving unit 35. Since the moving speed of the first arm 22 changes with the level of the rotational power output from the first actuating shaft K, monitoring the rotational power of the first actuating shaft K is equivalent to monitoring the moving speed of the first arm 22. The rotation power of the first actuating shaft K is controlled by the instant output of the driving unit 35, so the present invention can easily obtain the rotation power output by the first actuating shaft K through the control signal of the driving unit 35, and can monitor the moving state of the first arm 22 without complicated distance calculation.

Similarly, the second arm 23 of the present invention is rotated by the second actuating shaft L, and the present invention can monitor the moving state of the second arm 23 as long as the present invention obtains the rotating power output by the second actuating shaft L. However, the second actuating axis L is provided on the first arm 22, and the actual moving state of the second arm 23 can be monitored only by adding the moving state of the first arm 22, that is, by adding the rotational power output from the first actuating axis K to the rotational power output from the second actuating axis L. Similarly, the end portion 24 of the present invention is rotated by the third actuating shaft M provided on the second arm 23, and the present invention obtains the rotational power output by the third actuating shaft M, and the actual moving state of the end portion 24 can be monitored by adding up the rotational power output by the second actuating shaft L and the rotational power output by the first actuating shaft K. Therefore, the multi-axis robot arm needs to accumulate the output rotation power of each axis to form an accumulated total power, so as to monitor the moving state of the robot arm.

The present invention controls the robot arm 20 to move to pick and place objects, and teaches the robot arm operation path by planning and optimizing the path and speed. First, a total power limit G for all actuation axes is set at a total power setting unit 31. Following the trial teaching, the control device 30 controls the power monitoring unit 32 to record and monitor the rotational power of the first, second and third actuating axes K, L and M in the trial as indicated by the solid lines in fig. 2. The power comparison unit 33 is used to calculate the cumulative total power T of each actuation axis at a time point T, for example, and compare it with the set total power limit G, check whether the cumulative total power T exceeds the total power limit G, and continue to try the taught work path when the cumulative total power T does not exceed the total power limit G. Upon checking that the total power T exceeds the total power limit G, the control device 30 controls the power adjusting unit 34 to calculate a ratio P between the total power limit G and the total power T, and to adjust the rotating power of each actuating shaft, i.e. the rotating power of the first actuating shaft K ', the second actuating shaft L' and the third actuating shaft M ', according to the ratio P, so that the adjusted total power T' is not greater than the total power limit G. The control device 30 controls the driving unit 35 to receive the signal for reducing the rotation power of each actuating shaft, and controls each actuating shaft to rotate with the reduced rotation power, so as to continue to try the taught working path.

When the accumulated total power T exceeds the total power limit G, the rotating power of each actuating shaft is reduced according to the proportion P, so that the reduced accumulated total power T' is not greater than the total power limit G, the rotating speed of each actuating shaft is reduced in an equal proportion, only the moving speed is reduced, the original optimized path can be maintained, the operation path taught by trial can be completed, and the robot arm 20 can be controlled to produce according to the taught operation path under the condition of maintaining operation safety. Although the present embodiment uses the ratio P of the total power limit G to the accumulated total power T to reduce the rotating power of each actuating shaft, it can be inferred from the above description that the rotating power of each actuating shaft is reduced by not less than the ratio P, only the moving speed becomes slower, but the accumulated total power T can also be made not greater than the total power limit G, so as to achieve the purpose of maintaining the original optimized path.

Fig. 3 is a flowchart of a control method of the robot arm according to the present invention. Firstly, in step S1, planning an optimized path and speed, and teaching a working path of the robot arm; at step S2, a total power limit for all of the actuation axes is set; in step S3, the taught work path is tried, and the rotation power of each actuation shaft is recorded; in step S4, the cumulative total power of each actuation shaft is calculated periodically; in step S5, checking whether the accumulated total power exceeds a set total power limit, when the accumulated total power does not exceed the total power limit, entering step S8, and when the accumulated total power exceeds the total power limit, entering step S6, and calculating the ratio of the total power limit to the accumulated total power; in step S7, decreasing the rotation power of each actuation axis in equal proportion by not less than the proportion, so that the total accumulated power is not greater than the total power limit; in step S8, it is checked whether the trial job path is finished? If the trial job path is not finished, the process returns to step S3 to continue the trial taught job path, and if the trial job path is finished, the process proceeds to step S9 to finish the trial taught job path.

As described above, the control apparatus and method for a robot arm according to the present invention can control the rotational power of the actuation axes by setting the total power limit of all the actuation axes when trying to teach a working path, and limit the moving speed of each arm, thereby achieving the purpose of simplifying the working. In addition, when the comparison result shows that the accumulated total power exceeds the total power limit, the control device and the control method of the robot arm adjust and reduce the power of each actuating shaft in equal proportion by using the proportion of the total power limit to the accumulated total power, and maintain the optimized moving path and speed, thereby achieving the purpose of accelerating the completion of teaching operation.

The above description is only for the purpose of convenience of illustrating the preferred embodiments of the present invention, and the scope of the present invention is not limited to the preferred embodiments, and any modifications made according to the present invention shall fall within the scope of the claims of the present invention without departing from the spirit of the present invention.

Claims

1. A control device for a robot arm, for controlling the robot arm including at least one actuating shaft, comprising:

the total power setting unit is used for providing a total power limit for setting the rotating power of the actuating shaft;

the power monitoring unit records and monitors the rotating power of the actuating shaft;

the power comparison unit is used for recording the rotating power of each actuating shaft according to the power monitoring unit, regularly adding the rotating power of the actuating shafts to form accumulated total power, and comparing the accumulated total power with a set total power limit to check whether the accumulated total power exceeds the total power limit;

the power adjusting unit is used for adjusting and reducing the rotating power of the actuating shaft when the power comparing unit detects that the accumulated total power exceeds the total power limit, so that the adjusted and reduced accumulated total power is not greater than the total power limit;

and the driving unit receives a signal of reducing the rotating power of the actuating shaft by the power adjusting unit and controls the actuating shaft to rotate by the reduced rotating power.

2. The control device for a robot arm as claimed in claim 1, wherein the power adjusting unit decreases the rotational power of the actuating shaft in an equal proportion.

3. The control device for a robot arm as claimed in claim 1, wherein the power adjustment unit calculates a ratio of the total power limit to the cumulative total power to adjust the rotational power of the actuation axis to be not less than the ratio.

4. A control apparatus for a robot arm as claimed in claim 3, wherein the power adjustment unit adjusts the rotational power of the actuation axis down in proportion to the calculated total power limit and the accumulated total power.

5. A method for controlling a robot arm, comprising the steps of:

teaching a working path of the robot arm;

setting a total power limit;

the taught working path is tried, and the rotating power of each actuating shaft is recorded;

calculating the accumulated total power of each actuating shaft in a timing mode;

and when the accumulated total power exceeds the total power limit, regulating and reducing the rotating power of each actuating shaft to ensure that the accumulated total power is not greater than the total power limit, and continuing to try on the taught operation path.

6. The method of claim 5, wherein the cumulative total power is a sum of rotational power of each actuation axis.

7. The method as claimed in claim 5, wherein when the checking accumulated total power does not exceed the set total power limit, the taught operation path is continuously tried.

8. A method of controlling a robot arm as claimed in claim 5, wherein the rotational power of each of the actuating shafts is proportionally reduced upon checking that the cumulative total power exceeds a total power limit.

9. The control method of a robot arm according to claim 8, wherein a ratio of the total power limit to the cumulative total power is calculated so as not to be smaller than the ratio, and the rotational power of each of the actuation axes is reduced.

10. A method for controlling a robot arm as recited in claim 9, wherein the rotational power of each of the actuation axes is scaled down as a ratio of a total power limit to a cumulative total power.