JPS61292702A - Motor position controller - Google Patents

Abstract

PURPOSE:To obtain a motor position controller which can control a robot with high locus accuracy by changing the compensating element gain of a servo system according to the change of the moment of inertia, etc. CONSTITUTION:The output (u) of a speed controller 11 is supplied to a controlled system 10 and the speed is set at (v). Thus the momentary values (u) and (v) are supplied to an estimator 12 for estimation of the parameter (moment of inertia) of the controlled system 10. Based on this result of estimation, the controller 11 changes its coefficient (gain). While a position controller 31 calculates the value which is newly supplied to the controller 11 from the value supplied to the controller 11 and the target position value. Thus it is possible to cope with the change of the moment of inertia due to the change of posture of a robot arm and the change of disturbance torque of the centrifugal force, etc. Then the high locus accuracy is secured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to robot control 111, and relates to a motor position control device suitable for obtaining eK high trajectory accuracy.

[Background of the invention]

Conventional electric robot control is explained in pages 95 to 99 of Robotom 5B, edited and published by the Japan Industrial Robot Association.
This was done using the method described in.

However, it was not possible to deal with changes in the moment of inertia due to changes in the posture of the robot arm and changes in disturbance torque such as centrifugal force, resulting in poor trajectory accuracy.

[Purpose of the invention]

An object of the present invention is to provide a motor position control device that can control a robot with high trajectory accuracy by eliminating the drawbacks of the prior art described above.

[Summary of the invention]

The drawback of the prior art is that the gain of the compensation element of the servo system is kept constant; in other words, the present invention only needs to change this gain in accordance with changes in the moment of inertia, etc. Therefore, by configuring a speed control system by estimating the moment of inertia, etc., and further configuring a position control system in accordance with this speed control system, the trajectory accuracy of the robot can be improved.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 shows the general configuration of one motion axis of the robot. The control device 1 transmits the data to the amplifier 5 of the motor 4 via the D/A converter 2 from the movement target value, the current position Calculate the input μ given by Here, the relationship between the input μ and the current speed ν, which is the output, can be generally expressed as the following equation (System Identification, published by the Society of Instrument and Control Engineers, p. 77').

v(A)+α1 CA-1)+-”+α, u(A-n)
= AltL(AI)+・・・・・・+h, Itb
(A-ru)...(1) Here, α1...α@
*hl...H is an unknown parameter related to the moment of inertia, etc. These unknown parameters are determined from the input μ and the output V, for example, in System Identification, published by the Society of Instrument and Control Engineers.

Estimation is possible by the least squares method described in P75 to P79. In addition, in formula (1), for example, tlcA
-1), 1L('-1) c Each time (A-1)T
These are the values of the output V and the input μ at (T: sampling interval).

FIG. 2 shows the configuration of the speed control system when the above estimated values are used. The estimated value of the unknown parameter is α1・・・・・・◇・
, Starvation... Including... If the speed target value is expressed as υ, (A), then the human power tL(A-1) at time (A-1)T is.

Equation (1) The unknown parameters in K are estimated values, and v
By replacing (A) with the target value, the following equation is obtained.

△tL(A-1)=(v7(A)+cL1υ(4-1)+
...+α, v(A-n)-raμ(A-2)-...-
(A-n))/1... (2) The speed controller 11 obtains the input μ from the above equation. Furthermore, the estimator 12 estimates unknown parameters from the input μ and output V of the controlled object 1o, and modifies the coefficients of the speed controller 11 based on the estimation results.

Next, position x at time AT (4 as target position 3:, (A)
We will explain how to control this. A control system having preferable dynamic characteristics as a speed control system is assumed to be the reference model 21 in FIG. 5, and the relationship between the human power u, y and the output speed 17M is expressed by the following equation.

tJH(A)+a+MuyCA-1)+-"+ ayv
M(A-n)=bIMtLM('-1)-1-+h
mMlLMcA-rL) −・−,・mark・(5) Furthermore, at this time, the position Z obtained by integrating the velocity Uy by the integrator 22
The relationship between M and input μM is as shown in the following equation.

z (') + c 1M3cy ('-1) + -10c
aM"M (room m)=d1MtLM(A-1)+...
+d−rnMuM(A−rrL)・・・・・・・・・(
4) Here lm=3+1. The input t&H(A-1) that changes the position 'M(A) of this reference model at time JT to the target position sr(A) is rM in equation (4).
By replacing (a) with x and (A), the following equation is obtained.

uM(A-1) = (sr(A)+ CI M ri(
(A-1)+ ...+ CyHyZM(A-m)-4Ma
y(A-2)--d7rLh4ux ('-m))
/'m”f+[xJ4. xM, uy] ,,
, , , . . . (5) The output speed v M (4) of the reference model at this time is determined by substituting this IAM('-1) into equation (3).

-dntuM(A-2)-=-dmMtLIIJ('
m'))+h2MtLMcA-1)+-+hny1t
LM(A-yc)-alMvy(A-1) ”・(Z
syvM('-f'L)=f2C2r(A), Zy
# t'y + uMl −−−−−=−−−−−(
6) Therefore, position x(A) at time JT is set to target position 3:f
(The configuration of the position control system that is controlled at high speed is shown in Fig. 4.

That is, the position controller 51 determines the speed t1M of the reference model 21 based on the above equation (6), and sets this speed IJM as the speed target value of the speed control system 20. As a result, the speed υ of the speed control system 20 is controlled to the speed tJM of the reference model 21, and the position X obtained by integrating the speed υ of the speed control system 20 by the integrator 32 is controlled to the target value [,r,.

FIG. 5 shows "M + 9M" in equations (5) and (6) respectively.

υ, and by feeding back the actual position

〔Effect of the invention〕

According to the present invention, even if the parameters of the control system such as the moment of inertia change, the rotation angle of the motor can be controlled to a target angle, so the accuracy of the trajectory of the robot can be improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the entire motor control system according to an embodiment of the present invention, Fig. 2 is a block diagram of the speed control system, Fig. 5 is an explanatory diagram of the control system of the standard model, and Figs. is a block diagram of a position control system. 5... Amplifier, 4... Motor, 5... Tacho generator, 10... Controlled object, 11... Speed controller,
12... Estimator, 21... Normative model, 51...
Position controller, 20...speed control system. 2nd Kuniyoshi - 5 mouths

Claims (1)

[Claims] 1. A motor control system consisting of a controlled object consisting of a motor, a speed detection means for this motor, a rotation angle detection means for this motor, an amplifier that drives this motor, and a control device that gives commands to this amplifier. In this control device, an estimator for estimating parameters of the controlled object from input and output of the controlled object, a speed controller for the controlled object having a gain that changes depending on the result of the estimator, and the speed controller 1. A position control device for a motor, comprising a position controller that calculates a new value to be input to the speed controller from a value input to the speed controller and a position target value.