JPS61159390A - Method of controlling industrial robot - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling industrial robots such as articulated robots and SCARA robots.

[Conventional technology]

It is difficult to determine the optimal angular acceleration during movement of each axis of an articulated robot used for transfer, assembly, etc. This is because the movement of each axis influences each other, so the required torque for each axis varies depending on the position of the start and end points of arm movement, and it is extremely troublesome to analyze the required torque. This is because. Therefore, in conventional articulated robots, the angular acceleration of each axis is kept low.

[Problem that the invention seeks to solve]

As described above, by suppressing the maximum value of the angular acceleration of each axis of an articulated robot to a relatively low value, there is a problem in that the moving time of the arm becomes longer on average.

Therefore, an object of the present invention is to provide a method of controlling an industrial robot that does not require complicated motion analysis and reduces travel time.

[Means for solving problems]

The present invention provides a method for controlling an industrial robot having a plurality of axes that rotates a plurality of arms 2, 6, in which the plurality of arms 2, 6 are actually operated and the torques of the plurality of axes are measured as current values. step 22 of This method of controlling an industrial robot is characterized in that teaching data is modified by steps 23, 24, 25, 26, and 27 of changing the value of the angular acceleration of the axis.

[Effect]

The shaft torque is proportional to the current value. Therefore, by increasing the current value within a range where none of the current values for multiple axes exceeds the allowable current value, the angular acceleration of each axis can be increased without the need for complex motion analysis. . Thereby, travel time can be shortened.

〔Example〕

An embodiment of the present invention will be described below.

FIG. 1 shows an example of an industrial robot, such as a SCARA type robot, to which the present invention can be applied.

In this robot, a base part of a first arm 2 is rotatably supported on a base part 1, and a drive part 5 consisting of a servo motor 3 and a deceleration @4 arranged on the base part 1 drives the first arm. The second axis is rotated. A second arm 6 is rotatably supported at the tip of the first arm 2. first arm 2
The shaft of the second arm 6 is rotated by a drive section 9 consisting of a servo motor 7 and a speed reducer 8 arranged on the tip of the arm.

A hand 10 is attached to the tip of the second arm 6. In the SCARA type robot, both the first arm 2 and the second arm 6 move on the (XY) plane.

Servo motor 3.7: DC servo motor or A
A C servo motor is used. FIG. 2 shows the configuration of an example of a servo circuit for the servo motors 3, 7.

In FIG. 2, 11 indicates a microcomputer.

This microcomputer 11 supplies a speed command 13 and a direction command 14 to a speed program circuit 12 according to an operation control program.

The speed program circuit 12 is a microcomputer 11
The acceleration/deceleration curve is formed based on the commands from the controller. The output signal of this speed program circuit 12 is supplied to the servo pack 15. This servo pack 15 includes a speed detector 16
A speed signal from the position detector 17 and a position signal from the position detector 17 are fed back and supplied.

In the servo pack 15, the servo motor 18 is controlled by the feedback detection signal so that the arm moves along a predetermined acceleration/deceleration curve. FIG. 3 shows an example of an acceleration/deceleration curve.

In FIG. 3, the period from point A to point B is a section of constant acceleration, the period from point B to point 0 is a section of constant velocity, and the period from point 0 to point D is a section of constant acceleration. By this speed control from point A to point D, the axis is moved to the vicinity of the target point, and from point D the operation is switched to positioning. Then, the target position is reached at point E.

Therefore, the time from point A to point E is the travel time.

The configuration shown in FIG. 2 is provided for each of the servo motor 3 or servo motor tuft of the industrial robot shown in FIG. In this case, among the respective axes of arms 2 and 6, the speed of the other axis is adjusted to the axis that takes longer,
The two axes are arranged to perform synchronous motion.

Further, the memory of the microcomputer 11 has a teaching (
(teaching) data is stored.

This teaching data relates to the order, position, and time of the robot's movements. This teaching data is read out,
The microcomputer 11 calculates the position, velocity, acceleration, etc. of each axis, and outputs a speed command 13 and a direction command 14 to the speed program circuit 12.

In this embodiment, data related to angular acceleration of the teaching data is corrected by measuring the current value of the servo motor 18. The torque of the servo motor 18 or shaft is proportional to the current value.

FIG. 4 is a flowchart showing the operation for this modification.

First, the robot is actually operated (step 21).

At this time, the current value of each axis (current of the servo motor as a drive source for each axis) is measured (step 22). It is checked whether the current values of each axis are below the allowable current value (that is, the maximum usable current value) (step 23). If the current value of each axis is below the allowable current value, it is checked whether there is an axis where the allowable current value is, for example, 95% or more (step 24). If such an axis exists, the angular acceleration cannot be increased any further and the teaching ends.

If the current value of each axis is below the allowable current value, 95% of the allowable current value
If there are no more axes, the allowable angular acceleration value of each axis is increased, for example, by about 5% (step 25). The acceleration and velocity of each axis are determined so that each axis operates synchronously (step 26). If in step 23 all the axes are not below the allowable current value, the allowable angular acceleration value of each axis is lowered, for example, by 3% (step 27), and the process moves to step 26. Then, the process returns from step 26 to step 21, and the actual movement operation is performed. Thereafter, operations similar to those described above are repeated.

Note that determining whether the current is below the allowable current value is not limited to the method of manually observing the measured value, but also by converting the detected current into voltage and comparing this detected voltage with a reference voltage (corresponding to the allowable current value). ), and the above-mentioned corrective action may be automatically performed based on the result of this comparison.

〔Effect of the invention〕

According to the present invention, the optimum angular acceleration of each arm of an articulated robot can be set without performing a complicated motion analysis, and the arm movement time can be shortened.

[Brief explanation of the drawing]

Fig. 1 is a front view of an example of an industrial robot to which this invention can be applied, Fig. 2 is a block diagram of an example of a servo circuit to which this invention can be applied, and Fig. 3 shows acceleration/deceleration curves. The route map and FIG. 4 are flowcharts used to explain the present invention. Explanation of main symbols in the drawings 2: first arm, 3, 7: servo motor, 4° 8: speed reducer, 6: second arm. Agent Patent Attorney Masato Sugiura Figure 1 Figure 2

Claims (1)

[Claims] A method for controlling an industrial robot having a plurality of axes for rotating a plurality of arms, including the steps of actually operating the plurality of arms and measuring the torques of the plurality of axes as current values. , so that the current values of each of the plurality of axes are all lower than the allowable current value, and the current value of any one of the plurality of axes is approximately equal to the allowable current value. A method for controlling an industrial robot, comprising: modifying teaching data by changing the value of angular acceleration of an axis.