JPH01112413A - Robot controller - Google Patents

Abstract

PURPOSE:To attain locus control and robot control and to make the constitution simple and cheap by determining suitably a time constant at a first primary delaying means and a time constant at a second primary delaying means. CONSTITUTION:A teaching box 10 outputs the data to show the type of interpolation, moving position data and speed data, a main control 20 calculates a moving quantity based on these data and a machine parameter, executes a prescribed primary delaying processing, converts the quantity to moving quantities DELTAtheta1-DELTAtheta4 of respective shafts and outputs them. A servo control part 30 calculates a target value based on the data of the moving quantities DELTAtheta1-DELTAtheta4 of respective shafts and the present position of respective shafts from a robot main body 40, executes a prescribed primary delaying processing, calculates the deviation with the present position, executes the digital analog conversion and outputs it to the robot main body 40 as deviations e1-e4. In the robot main body 40, respective shafts are controlled so that the deviation can be 0 based on the servo output.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a robot control device, and particularly to a robot control device suitable for application to a robot with a high maximum speed.

[Conventional technology]

Recently, robots with a considerably high maximum speed of, for example, 500 m/sec have been developed. When controlling such a robot, since accurate position control becomes difficult with a uniform speed pattern, it is necessary to create acceleration/deceleration patterns in accordance with each drive command.

However, it is quite difficult to create an acceleration/deceleration pattern according to each drive command, and in particular, when creating a deceleration pattern, it is necessary to perform recalculation every time the override 0 of the robot changes.

[Problem that the invention seeks to solve]

As mentioned above, in the control device 20 of a robot with a high maximum speed, accurate position control is achieved by creating an acceleration/deceleration pattern, but in this case, since it is quite difficult to create the acceleration/deceleration pattern, by this,
Robot system a The disadvantages are that the cost of the device is high and the device is also large.

An object of the present invention is to provide a simple and inexpensive robot control device that can be applied to a robot with a high maximum speed without creating an acceleration/deceleration pattern.

[Means for solving problems]

In this invention, the generation of acceleration/deceleration patterns is stopped, and a first-order delay method is adopted instead. That is, the robot control gA device of the present invention includes a main control means that calculates the movement 0 of the robot in each interpolation period based on input data, and outputs movement data indicating the amount of movement in synchronization with the interpolation period. and a servo system that inputs the movement O data output from the main control means and data indicating the current position of the robot, calculates the target movement amount in each servo processing cycle, and drives the robot based on this target movement C. Servo control means to control the robot! In the apparatus, the main control means receives the calculated movement vJ.
A first primary delay means is provided for performing a first primary delay process on the convexity, and a second primary delay process is provided in the servo control means for performing a second primary delay process on the calculated target movement amount. It is characterized by providing two primary delay means.

[Effect]

According to this invention, the first primary delay means in the main control means executes the predetermined first primary delay process, and the second primary delay means in the servo control means executes the second primary delay process. executed. By appropriately determining the time constant in the first 1-hour delay means and the time constant in the second 1-hour delay means, trajectory control and speed control can be achieved with sufficient accuracy.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of a robot control device according to the present invention. This embodiment is applied to control of a 4-axis vertical multi-articulation robot. The teaching box 10 outputs data indicating the type of interpolation, such as linear interpolation or circular interpolation, movement position data obtained by teaching, and speed data representing the movement rjjJ speed. The main controller 20 calculates the amount of movement ΔLi in each interpolation period Δt1 based on the interpolation type data, position data, speed data obtained from this teaching box, and machine parameters representing the length of each part of the robot input in advance. Then, a predetermined first-order lag process is executed on this movement OΔLi, and the movement vJ-dake ΔLO subjected to this first-order lag process is converted into movements 0Δθ1, Δθ2, Δ03, Δ04 corresponding to each axis, and these are It is output every interpolation period Δt1.

The robot control unit 30 receives the movement amounts Δθ1 to Δθ4 of each axis inputted from the main control unit 20 and the current positions OF1, OF2, θ[
3. Based on the data representing OF4, the target value n1 of the movement vJ of each axis per 1 servo processing cycle Δt2,
n2, n3, n4, a predetermined first-order lag process is executed for these target values n1 to n4, and the target values n01, nG2, nG3, nG4 that have been subjected to this first-order lag process and each axis of the robot are Deviation no1 from current position nF1 to nF4
-nF1, n G2- 'n F2, nG3-nr3,
n G4- n F4 are calculated respectively, and this deviation is converted into digital/analog to obtain deviations el, G2, G3, G
4 to the robot wooden Buddha 40.

FIG. 2 shows the main control section 20 and the servo control section 30.
The processing operation is shown in flowchart 1. In FIG. 2, the flow on the left side shows the processing operation of the main control section 20, and the flow on the right side shows the processing operation of the servo control 2130. Further, FIGS. 3 and 4 are schematic diagrams showing each axis and machine parameters of a 4-axis vertical polygonal robot (welding robot) to which this embodiment is applied. FIG. 3 is a side view of the robot, and FIG. 4 is a top view of the robot. The welding robot to which this embodiment is applied has a main body 41.
A first arm 42 is attached to the first arm 4.
A second arm 43 is attached to the second arm 43, a third arm 44 is attached to the second arm 43, a fourth arm 45 is attached to the third arm 44, and a fourth arm 45 is attached to the third arm 44. A welding torch 46 is attached to the tip. The lengths of the first arm 42, second arm 43, third arm 44, and fourth arm 45 are Ll and F.
2, F3, and F4. Further, among the drive shafts, the first axis corresponds to the rotation angle θ1 of the first arm 42 with respect to the main body 42, the second axis corresponds to the rotation angle θ2 of the second arm 43 with respect to the first arm 42, and the third axis corresponds to the rotation angle θ2 of the second arm 43 with respect to the first arm 42. The rotation angle θ3 of the third arm 44 with respect to the arm 43 is set to θ3, and the fourth axis is set to the rotation angle θ4 of the fourth arm 45 with respect to the third arm 44. Also, the angle shown in Figure 4! Bean O8 is the rotation angle (
station angle).

In FIG. 2, first, in step 21, the amount of movement ΔL in the angular interpolation period Δt1 is determined based on the interpolation type data, position data, speed data input from the teaching box 10, and machine parameters input in advance.
i@-calculate. Here, the position data is the position of the workpiece,
That is, data (X, Y, Z, G4) using a workpiece coordinate system in which the position of the tip of the fourth arm 45 to which the torch 46 is attached is expressed in an X-Y-Z coordinate system is used, and step 21 The movement compensation ΔLi calculated using this workpiece coordinate system (ΔL×, ΔLY.

ΔLZ, ΔL04). Further, the interpolation period Δt1 here is, for example, 39 rasac, and one servo processing cycle Δt 2 (= 311
1SeC). Also, the maximum speed specified by the speed data is, for example, 500 m.
tn/Sec.

In step 22, a predetermined first-order delay process is performed on the shift vJ wave ΔL1 calculated in step 21. This first-order delay processing is realized by repeatedly performing the following operations using registers (not shown).

C(k)=C(k-1)+ΔLlFk)
...(1) ΔLo(k)=G1 ・C(k)
...(2) C(k) = C(k)
−ΔLo(k) ...(3) Here ΔL
i(k) indicates the movement command value of each axis using the work coordinate system at time, ΔLO(i) indicates the first-order lag command value of each axis using the work coordinate system at time, G1 is a predetermined constant C(k) indicating the contents of the register at the time.

The calculations shown in equations (1), (2), and (3) are the same as those used in ordinary discrete time systems, and are suitable for processing using a computer. When the value G1 is 1, it is equivalent to "no first-order delay". The response time constant changes according to this value G1.

An example of the first-order delay processing in step 22 is shown in FIGS. 5(a) and 5(b). In other words, Fig. 5 (a
) When a first-order delay process is applied to the movement command value ΔLi as shown in FIG. 5(b), a command value ΔLO as shown in FIG. 5(b) is obtained.

The command value ΔLO, which has been subjected to first-order delay processing in step 22, is determined in step 23 for each axis, that is, O1.02.03.
．． The coordinates are converted to a command value Δθi corresponding to 04.

The command value Δθ1 indicating the movement vJ of each axis per interpolation cycle calculated as described above is outputted from the main control unit 20 to the servo control unit 30 every interpolation period Δt2.

The servo control unit 30 first goes to step 31 and performs 1
Servo processing cycle 1 Every servo processing cycle Δt2, the value θ[1 indicating the current position of each axis of the robot is fetched, and in step 32, the value θ[1 indicating the current position fetched in step 31 is received from the main control unit. The target 1i n i of the movement of each axis of the robot per one servo processing cycle Δt2 is calculated based on the command value Δθi without considering the movement vJ side of each axis for each interpolation period. Here, one servo processing cycle Δt2 is set to, for example, 3 n5ec .

Next, in step 33, a predetermined first-order lag process is performed on the target value ni calculated in step 32. The first-order delay processing in step 33 is performed in step 2.
This is similar to the first-order delay processing in 2. That is, in step 33, the following calculation is repeated using a register (not shown) of the servo control section 30.

R(k) = R(k-1) + n1(k)'
(4) noi(k) = G2 ・R(k)
(5) R(k) = R(k) −n oi(
k) (6) Here, nl(k) indicates the target value at time, noi(K) indicates the first-order delayed target value at time, G2 is a predetermined constant, and R(k) is the time does not show the contents of the registers.

FIG. 5(C) shows the 1 sir calculated in step 32;
An example of the target value ni of the shift vJ0 per processing cycle Δt2 is shown, and FIG. 5(d) shows an example of the first-order lag target value subjected to the first-order lag process in step 33.

In step 33, the first-order lag target value and the step 31 described above are determined.
A servo calculation is executed to find the deviation from the current position @OFl taken in, and then this deviation is converted into digital/analog in step 35 and sent to the robot main body 40 as a servo output.

In the robot main body 40, each axis is controlled based on this servo output so that the above deviation becomes zero.

In the above embodiment, the constant G that determines the time constant of the first-order delay processing in the main control section in step 22 is
1 is constant, but the trajectory accuracy can be further improved by changing the constant G1 according to the robot's command speed and setting the constant G1 to be small in the high speed range of the robot and large in the low speed range.

In addition, the primary purpose of the first-order delay processing in the servo control section, that is, the processing that goes to step 33, is to smooth out the step-like command value given from the main control section, and for this reason, the servo control section The constant G2 that sets the @constant in the first-order delay process is 1 in the main control section.
The constant G2 is set to a value smaller than the constant G1 that determines the time constant of the next delay process, and the constant G2 can be a semi-fixed value that does not depend on the command speed.

Also, in the calculation n of equation (2) in step 22 or the calculation of equation (5) in step 33, the value C(k)
Or, when R(k) is a small value, depending on the value of G1 or G2, when the value ΔLo(k) or noi(k) is converted into an integer, ΔLo(k) = O or noi(k) = 0. Sometimes. In this case, the target position cannot be reached. So, solve this inconvenience! In order to do this, the following "exposure process" is executed.

That is, when executing equation (1) or (5), the preset output value CH01RHO and the values C(k), R
Compare with (k). If C(k) <CHD or Rfk) < RHO holds here, then equation (2) or (5
), G1 and G2 are each set to 1.

This eliminates the above-mentioned inconvenience.

Although the above embodiment shows the case where the present invention is applied to a 4-axis vertical welding robot welding robot, the present invention can also be applied to multi-joint robots with 5 or more axes such as 5-axis and 6-axis. It goes without saying that it can be applied not only to vertically articulated robots but also to horizontally articulated robots, and also to other work robots other than welding robots.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to control the trajectory and speed of a high-speed robot without creating an acceleration/deceleration pattern, and it is possible to provide a simple and inexpensive robot control device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the robot control device of the present invention, FIG. 2 is a flowchart explaining the operation of the embodiment shown in FIG. 1, and FIGS. 3 and 4 are similar to those shown in FIG. A schematic diagram showing an example of a welding robot to which the illustrated embodiment is applied;
FIG. 5 is a graph showing a specific example of the first-order delay processing on the main control section side and the servo control section side shown in the m2 diagram. DESCRIPTION OF SYMBOLS 10... Teaching box, 20... Main control part, 30... Servo control part, 40... Robot main body. 2nd ffl

Claims (4)

[Claims] (1) a main control means that calculates the amount of movement of the robot in each interpolation period based on input data and outputs movement amount data indicating the amount of movement in synchronization with the interpolation period; servo control means that inputs movement amount data and data indicating the current position of the robot, calculates a target movement amount in each servo processing cycle, and controls a servo system that drives the robot based on the target movement amount. In the robot control device, the main control means is provided with a first primary delay unit that performs a first primary delay process on the calculated movement amount, and the servo control unit is provided with a first primary delay process that performs the calculation on the calculated movement amount. A control device for a robot, characterized in that a second primary delay means is provided for performing a second primary delay process on a target movement amount. (2) The first primary delay means executes 1 hour lag processing based on a small time constant in the high speed range of the robot, and executes 1 hour lag processing based on a large time constant in the low speed range of the robot. A robot control device according to claim (1), characterized in that: (3) The first primary delay means and the second primary delay means input data at time k as Di(K), output data as Do(k), register contents as C(k), and G as a constant. When C(k)=C(k-1)+Di(K)...(1)Do
(k)=G・C(k)...(2) C(k)=C(k)-Do(k)...(3) A control device for a robot according to scope item (1). (4) The robot according to claim (3), characterized in that when calculating equation (2), if C(k) is smaller than a preset value, the value G is changed to 1. control device.