JPS6369478A - Speed control method - Google Patents

Abstract

PURPOSE:To simplify the arithmetic operation of observers by providing a motor part and a machine part with individual observers in which the angular displacement of the machine part computed through the estimate of the load disturbance of the observer of the motor section is regarded as a true value. CONSTITUTION:Observers are composed of a section estimating the speed of a motor and a section estimating the tip speed of a machine, which are separated from each other. By signal(a), a constant ratio as the estimate of the speed of the motor is fed back, and by signal(b), a constant ratio as the estimate of the speed of the machine is fed back. By regarding the signal(c) of disturbance torque as a true value, the true value of the tip speed(angular displacement) of the machine is to be formed with signal(d). As a result, the composition of the observers can be simplified, and the speed can be estimated without the need of complicated arithmetic operations.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a speed control method in which a mechanical part coupled to a motor with a spring coefficient is controlled.

(Prior art) In a speed control system where a DC motor drives a low-rigidity mechanical load, such as a robot arm, a torque command is obtained from the deviation between the speed command and the actual speed, and this torque command is used to control the motor. is driven to move the mechanical load at a commanded speed. The schematic structure of this type of speed control system can be represented by a block diagram as shown in FIG. 4. In FIG. 4, Jm is the rotor inertia, J is the load inertia inertia, and K is the spring coefficient.

In such a speed control system, the motor speed signal ■
If relatively accurate measurement of the mechanical load tip speed (angular position) is possible, the mechanical load tip speed (angular position) can be detected accurately, but sensors are generally expensive and mounting problems due to location and accuracy. Therefore, an estimator (observer) may be used to estimate the speed.

FIG. 5 is a block diagram when estimating the speed of the mechanical part, which is the output of the speed control system in FIG. 4, using an observer. In FIG. 4 is a constant in K1-. The state equation of such a speed control system using an observer is expressed as follows.

...(1) ...(2) Therefore, the same-dimensional observer configured as shown in FIG. 5 is expressed as j 1.0] ... (3). However, in reality, it is necessary to change such processing in a continuous system to processing in a discrete system, and the variable x
, y is expressed as a vector, then = Aex + lBe au
-(4)v-CC11g,
...(5), however, Ae, I
Be and Ce are each vector quantities. Assuming a θ-dimensional holder, the equation in the discrete system is x (i+1)=Ad*ic (i)+rf3du...
・(6) y (i)=Cdx (i) ...(7
). Here, A d = exp (A T ) Bd = I exp (At) dt - Be Cd = Ce (8), where T is the sampling period.

Also, exp(At) = d-'((SN-Ac)
' )...(9) where ■ is a unit vector.

(Problems to be Solved by the Invention) Considering the controlled object shown in FIG. 4, the expansion formula for one matrix Ad, i.e.
The coefficient is determined by the eigenvalue, that is, the root, determined by Ac=0. However, the spring constant K, load inertia and JL
With respect to fluctuations in , the above-mentioned observer has a problem in that the parameters are complicated and the coefficient calculation procedure becomes complicated, and it has to be performed using a complicated calculation means, which is not practical.

Therefore, the present invention aims to solve the problems of the prior art (1) by providing a speed control method that allows an observer to accurately and efficiently observe the state of the speed control system and estimate the machine speed. This is what we provide.

(Means for Solving the Problems) The present invention is to estimate disturbances applied to the motor and the mechanical part from a load on the motor in a speed control system that controls a mechanical part coupled with a motor with a spring coefficient. It has an observer for the motor section that outputs a value, and an observer for the mechanical section that calculates the angular displacement amount of the mechanical section from this estimated value and considers it as the true value. The present invention provides a speed control method characterized in that the estimated value of the bar is used as the estimated speed of the mechanical part.

(Function) When the speed of a low-rigidity mechanical load connected to a motor shaft is estimated by an observer, the present invention provides separate observers for the motor section and the mechanical section, and provides an estimated value of load disturbance to the motor section. By regarding the amount of angular displacement of the mechanical part obtained from the equation as the true value, the estimated value of the observer of the mechanical part is used as the estimated value of the speed of the mechanical part.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. Second
The figure is a block diagram when considering a model without a resonance system on the motor side. In this case, the motor speed signal x2 can be measured, and it becomes (X2-X2) at the point ■ and 2 (X2-X2) at the point ■. Then, the torque balance is kz (X2
(s)...(10) Represented by: Here, the control system in FIG. 4 is represented by the block diagram in FIG. 3, and the disturbance D (5
) is regarded as its true value, the speed of the machine tip X4
can be measured.

Therefore, in the present invention, as shown in the block diagram of FIG. 1, the observer is configured to be divided into a part for estimating the speed of the motor and a part for estimating the speed of one machine tip. In other words, the observer's wide range in Figure 5 is divided into two parts in Figure 1. Signal 0 feeds back a fixed percentage as the estimated value of the motor speed, and signal ■ feeds back a fixed percentage as the estimated value of the machine speed. do. Further, by regarding the disturbance torque signal ◎ as the true value, it is assumed that the signal ■ is formed by the true value of the speed (angular displacement amount) X4 of the machine tip. That is, the disturbance torque is estimated to have a true value with a fairly high probability, and a 0-part signal is formed.

In this way, in the present invention, when estimating the speed of the machine tip, the observer (when estimating the speed of the machine tip) is divided into a part for estimating the motor speed and a part for estimating the machine speed, and the disturbance torque estimated by the estimator of the motor part is By considering the real value, the observer configuration can be simplified and complex calculations are not required.
Speed can be estimated.

(Effects of the Invention) As explained above, in the present invention, when estimating with a speed control system that drives a low-rigidity load by a DC motor, an observer is used as a part that estimates the speed of the motor section and a part that estimates the speed of the motor section.
The observer of the mechanical part is configured to regard the angular displacement amount of the mechanical part calculated from the estimated value of the load disturbance of the observer of the motor part as the true value. Since the estimated speed of the observer is used as the estimated speed of the mechanical part, the calculation of the observer can be simplified even for a controlled object formed in a discrete system.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the present invention, Figure 2 is a block diagram of a model without a resonance system, Figures 3 and 4 are block diagrams of the controlled object, and Figure 5 is a block diagram of a conventional example. It is. Jm...Rotor inertia, JL...Load inertia, D(s)...Disturbance torque.

Claims (1)

[Claims] In a speed control method in which a mechanical part coupled to a motor with a spring coefficient is controlled, an observer of the motor part outputs an estimated value of disturbance applied to the motor from a load to the motor part and the mechanical part, and an observer of the motor part outputs an estimated value of a disturbance applied to the motor from a load, and a and a mechanical part observer configured to calculate the angular displacement amount of the mechanical part and regard it as a true value, and the estimated value of the mechanical part observer is used as the speed estimated value of the mechanical part. speed control method.