JPH0277905A - Correcting method for robot moving program - Google Patents

Abstract

PURPOSE:To correct a track error and to reduce a route error by simulating the position of a point corresponding to an interpolation point set between the block start and end points where a robot passes through and correcting a program when the deviation obtained from the simulation is larger than the set value. CONSTITUTION:When the start is applied from a control panel 4 for correction of a robot moving program, a processor 1 reads the position data on the start and end points Ps1 and Pe2 of the j-th block (initial value of j = 1) out of a RAM 3 and stores the coordinate value of an interpolation point P1 between both points Ps1 and Pe2 into the RAM 3. Then the data on the point P1 from the P1 through an interpolation point P2i for each time Ts, and the locus control is performed so that a robot may pass through the point P2i. In this case, the position of a position P1i where the robot actually passes is simulated. The deviation between both points P2i and Pi is compared with the allowable value of the route error set previously. When this deviation is larger than the allowable value, the position of the point P2i is corrected repetitively. Thus the deviation is set less than the allowable value.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for modifying a program for robot movement, and particularly to a method for modifying a program for robot movement that can reduce path errors.

<Prior art> Conventionally, in order to control the trajectory of the robot 1-, first the coordinate values of the start and end points of the block specified by the robot movement program are converted from the robot's respective axis values to the orthogonal coordinate values (for example,
When moving the robot, for example, on a straight line connecting the block start point and end point, a predetermined sampling period (interpolation period) Ts is performed between the block start point and end point. It is divided into multiple parts by the distance d that it moves between. After that, the coordinate values of each division point (interpolation point) obtained by orthogonal coordinate values are inversely converted to each axis value of the robot, and the command data for each axis of the robot obtained by the inverse conversion is subjected to acceleration/deceleration filtering. is applied and output to the servo, and path control is performed so that the robot follows each interpolation point from the block start point to the block end point. Note that the acceleration/deceleration filter processing is
A pulse interpolation calculation is performed on the command data for each axis of the robot at each interpolation point at a predetermined distribution cycle T (usually Ts is determined to be an integral multiple of To) to generate pulses.
The pulse train created by the pulse interpolation is input to the acceleration/deceleration circuit, and one frequency is the block starting point.

It is converted into a pulse train that gradually increases and gradually decreases at each end point, and the pulse train is input to a servo circuit.

<Problem to be solved by the invention> By the way, in the conventional technology, the acceleration/deceleration filter is
``accumulation'' or ``servo delay'' occurs.

This "stagnation" and "servo delay" cause the robot to move along a trajectory that deviates from the target trajectory. In particular, "accumulation" and "
There has been a problem in that the larger the difference in servo delay and the larger the moving speed, the larger the trajectory deviation.

From the above, the purpose of the present invention is to "accumulate" acceleration and deceleration.

It is an object of the present invention to provide a robot movement program correction method capable of correcting trajectory deviations due to the influence of "servo delay" of a servo system and reducing path errors.

〈Means for solving problems〉 FIG. 1 is a schematic explanatory diagram of the present invention.

Ps is the block start point, Pe is the block end point, pi is the interpolation point, Pzi is the point that the robot actually passes, P
21 is an interpolation point after correction.

Effect> When one or more interpolation points pi are generated between the block start point Ps and end point Pe specified by the robot movement program, and the trajectory is controlled so as to pass through the interpolation points pi, the robot actually The interpolation point P which is a point to pass through
Simulate the position of point P11 corresponding to i,
Find the deviation between the simulated position of point Pxi and the position of interpolation point Pi specified by the control program, and if the deviation is larger than a set value, interpolate the position of interpolation point P0 so that it is less than or equal to the set value. The robot movement program is corrected to the position of point Pat, the corrected interpolation point Pzi becomes the target position, and a program is created in which the interpolation point P2□ is inserted between the block start point Ps and end point Pe.

<Embodiment> FIG. 2 is a block diagram of a robot control device that implements the robot movement program modification method of the present invention.

Figure 3 is a linear acceleration/deceleration characteristic diagram, Figure 4 is a servo delay characteristic diagram, Figure 5 is a flowchart of the process of the program modification method according to the present invention, and Figure 6 is an example of a program modified according to the present invention. be.

In FIG. 2, numeral 1 denotes a processor, which performs a program correction process to be described later to create a program with fewer route errors, and also performs well-known path control processing using the path data of the program.

2 is a ROM that stores a control program for modifying the robot movement program and a control program that executes numerical control processing based on the movement program; 3 is a RAM that stores the robot movement program and processing results;
Reference numeral 4 represents an operation panel, and reference numeral 65 represents a pulse interpolator provided for each axis of the robot.

6 is an acceleration/deceleration circuit provided for each axis of the robot;
It accelerates when the interpolation pulse output from the pulse interpolator 5 rises, and decelerates when it falls. In addition, the acceleration/deceleration circuit 6 is 9
For example, acceleration/deceleration control is performed according to linear acceleration/deceleration characteristics having a time constant T□ shown in FIG.

Reference numeral 7 indicates a servo circuit, and reference numeral 8 indicates a servo motor, both of which have a position and velocity feedback configuration (not shown), and as a whole have a temporary delay characteristic with a time constant T2, as shown in FIG. 4, for example.

9 is an interface circuit that controls data exchange between the robot IO and the main body of the robot control device.

The present invention will now be described in detail with reference to the flowchart shown in FIG. It is assumed that the robot movement program (FIG. 6(a)) for specifying the starting point PS and ending point Pe of each block has already been created and stored in the RAM 3.

When the robot movement program is modified and activated from the operation panel 4, the processor 1 stores the start point Ps□ and end point Pe of the j-th block (the initial value of j is 1) from the RAM 3.

The position data of is read (step 1o1).

Next, the processor 1 converts the coordinate values of the block start point Ps and end point Pe1 from the robot coordinate system to the orthogonal coordinate system, and then calculates the distance 1lill to be moved during the interpolation period Ts.
(=F-Ts, where F is the feed rate) Te block starting point,
Divide between the end points and divide each dividing point (interpolation point Pi (i=1,
2...) in the orthogonal coordinate system, and then the coordinate values of the interpolation point P1 are inversely converted to the values of each axis of the robot, and the coordinate values are stored in the RAM 3 as shown in FIG. 6(b). Store (step 102). - Next, the data of the interpolation point Pi is transferred to PZ-4 every time Ts elapses.
Step 103), the interpolation point P
21 (that is, pt), the position of point PLi, which is the point that the robot actually passes through and corresponds to the interpolation point P2□ (Pi), is calculated using the following formula (1). Simulate (step 104).

S (A (P21) )→Pxi・・・・・・＜I
) Note that S is a function representing the evaluation amount depending on the servo delay of each axis, and A is a function representing the evaluation amount depending on the filter of each phase acceleration/deceleration, which are determined in advance from the measurement results.

Next, the deviation ΔPi between the position of the simulated point Pzi and the position of the interpolation point pi specified by the control program is calculated using the calculation formula % () (step 105), and the deviation ΔPt is calculated from the predetermined value. Compare the path error (deviation) with the allowable value (Step 106), and if the deviation is larger than the allowable value, correct the position of the interpolation point P2 using the formula % () so that it is below the allowable value. Step 107), thereafter Step 104
The subsequent processing is repeated to set the deviation ΔPi to be less than or equal to the allowable value. Note that the function f (Δpt) serving as the correction amount is experimentally set according to the model used and the motor selected.

On the other hand, if the deviation is smaller than the allowable value as determined in step 106, as shown in FIG. A correction process is performed (step 108).

As mentioned above, the correction amount f(ΔPt) is determined according to the deviation ΔP1.
is determined, and the interpolation point P21 that causes a path error in the position of the initially targeted interpolation point Pi when the deviation ΔPi occurs is corrected as the interpolation point position on the program.

From then on, until all interpolation point correction processing is completed (steps)
09) Correct each interpolation point, modify the movement program so that the interpolation point Psi obtained by the correction process is the target position for each interpolation period Ts, and set the interpolation point P2□ between the block start point Ps and end point Pe. (See Figure 6(c).) By doing this, the original target trajectory (interpolation point I) is created when actually controlling the position of the robot.
) is obtained.

Note that one or more correction processes are performed on all blocks.

<Effects of the Invention> According to the present invention, one or more interpolation points are inserted between the block start point and end point specified by the robot movement program, and the trajectory is controlled so as to pass through the interpolation points. Simulate the position of a point that the robot actually passes through and that corresponds to the interpolation point, find the deviation between the simulated point position and the interpolation point position specified by the control program, and calculate the deviation. If the position of the interpolation point is greater than the set value, the position of the interpolation point is corrected so that it is less than or equal to the set value, and the robot movement program is corrected so that the corrected interpolation point becomes the target position. Acceleration/deceleration [accumulation].

It is possible to reduce the deviation in the trajectory due to the influence of "servo delay" of the servo system, etc., and improve the accuracy of the trajectory.

Further, since the present invention is carried out off-line before the robot actually operates, the program can be easily modified even if the program cannot be modified in real time due to the computing power of the control element.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of the present invention, FIG. 2 is a block diagram of a robot control device that implements the robot movement program correction method of the present invention, and FIG. 3 is a linear acceleration/deceleration characteristic diagram. Fig. 4 is a servo delay characteristic diagram, Fig. 5 is a flowchart of the process of the program modification method according to the present invention, and Fig. 6 is an example of a program modified according to the present invention, Ps
...Block start point, Pe...Block end point, Po...Interpolation point, Pli...Point that robot 1 actually passes through, P2
1... Interpolation point after correction. Patent Applicant Fanuc Co., Ltd. Agent Patent Attorney Chiki Saito Figure 1 Figure 3 Figure 5 Figure 6 (σ) (b) (')

Claims (1)

[Claims] One or more interpolation points are generated between a block start point and an end point specified by a robot movement program, and when the trajectory is controlled so as to pass through the interpolation points, the robot actually passes through the interpolation points. simulating the position of a point that corresponds to the interpolation point, and determining the deviation between the simulated point position and the interpolation point position specified by the control program, and if the deviation is larger than the set value; A method for modifying a program for robot movement, comprising: correcting the position of the interpolation point so that it is below a set value, and modifying a program for robot movement so that the corrected interpolation point becomes a target position.