JPS61114304A - Digital controller - Google Patents

Abstract

PURPOSE:To shorten the sampling time and to attain the servo control at a high speed by using exclusively a digital signal processor to perform each operation of servo control. CONSTITUTION:A target position Xc, a target speed Vc, etc. are delivered from a host processor 1, and a motor 13 is controlled via a D/A converter 11 and a power amplifier 12. Here a digital signal rocessor DSP10 is provided and executes exclusively the multiplication and addition at a high speed for voice synthesization, etc. The DSP10 contains an observer 10-1, an integration circuit 10-2, a function generating circuit 10-3, an arithmetic circuit 10-4, etc. Thus the DSP10 reads the present position by an encoder 14 for each sampling time point and at the same time calculates the optimum control amount U. The motor 13 is controlled by the control amount U.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the control of mechanical systems such as robot control, and particularly to a digital servo control device that can perform high-speed calculations in its servo*a. It is something.

[Conventional technology]

For example, in the case of vIrIJ of a robot, a servo control device that gives a target value and makes it follow the target value has a numerical value generator 20 as shown in FIG.
When c and target speed Vc are input, the corresponding target value XR and acceleration αR are output only at the beginning of the movement of the motor 24. αR is necessary to increase the start-up (response speed) of the motor.

This acceleration αR is converted into an analog value by a D/A conversion circuit 21, and is amplified by a power amplifier 23 via an adder 22, and then drives a motor 24. The current position of the motor 24 is detected by an encoder 25, the output pulses of the encoder 25 are counted by a counter 26, this is compared with the target value XR by a comparator 27, and the digital value of the difference is converted into a D/A converter. The circuit 28 converts the signal into an analog signal.

The analog value of this D/A conversion circuit 28 indicates the deviation between the target value and the current value, and this is transmitted to a simulator called a state observer 30 and an integrator 29 and estimated from the state observer 30. The estimated speed deviation value Z1 and the estimated position deviation value z2 are output, and the integrator 29 outputs the integral value z3 of the position deviation. Each of these values 21, z2 and z3 is input to the coefficient circuit 33, 32 respectively.
．． 31 multiplies the feedback coefficient by +3 and sends it to the adder 22 via addition 1s 34.35, and becomes an input to the power amplifier 23, which controls the motor 24 accordingly.

In other words, it is desirable for conventional servo control devices to feed back all the state variables of the system in order to perform good control, but it is not always possible to measure them all. Therefore, a simulator called an observer is used to measure the state of the system. Estimate variables. The state variables estimated in this way are multiplied by an appropriate feedback coefficient using the optimal regulator theory and fed back.

The function generator 20 generates a smooth target value function so that the servo control device can follow the target value command from the host processor.

In the circuit shown in FIG. 4, the estimated speed deviation value "Zs", the estimated position deviation value Zz, and the integral value of the position deviation 2
3 etc. are analog values, and the observation device 30, the integrator 29, and each coefficient circuit 31 to 33 are composed of operational amplifiers, and conventionally, analog technology has been used for such a circuit configuration.

[Problem that the invention seeks to solve]

However, in analog control circuits, controller parameters are set using resistors, capacitors, etc., so once fixed, the characteristics of a controlled object such as a robot change with movement or the passage of time. Since it is necessary to change the parameters of the controller according to changes in the characteristics, there is a drawback that good control cannot be performed. Furthermore, since multiplication and addition are performed using operational amplifiers, there are inevitably problems with drift and offset, which are difficult to compensate for.

Therefore, a software system W (
Digital systems (vIJ) have been implemented in recent years, but software control using microcomputers has a slow calculation speed (and therefore a long sampling period), making it difficult to maintain sufficient control especially when high-speed operation is required, such as in robots. I couldn't improve the performance.

In digital control, it is essential to make the sampling time, that is, the interval at which the controlled variable is input to the controlled object, as short as possible in order to perform good control that is resistant to external disturbances. The problem was that they could not respond to this request.

[Means for solving problems]

In order to provide a high-speed digital control device that solves the above-mentioned problems, the present invention includes a target value output means for outputting a target value, a controlled object that is controlled to reach the target value, and a controlled object that is controlled to reach the target value. A digital servo control device that compares the target value and the state of the controlled object and controls the controlled object according to the difference, includes an observer function and an integral function. Digital
It is characterized in that it is equipped with a signal processor, the servo system part is separated from the host processor, and servo calculations are performed by this digital signal processor.

[Effect]

In the present invention, each servo control operation is performed using a dedicated digital signal processor that can perform digital operations such as multiplication and addition at high speed. It is capable of strong, accurate, and high-speed servo control.

〔Example〕

An embodiment of the present invention will be described based on FIGS. 1 to 3.

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIG. 2 is a block diagram thereof, and FIG. 3 is a flow chart explaining the present invention in detail.

In the figure, 1 is a host processor that outputs target position Xc, target velocity Vc, etc., 10 is a digital signal processor (hereinafter referred to as DSP), and 1 is a D/A.
1 is a converter that converts the digital value output from the DSPLo into an analog value; 12 is a power amplifier corresponding to the power amplifier 23 in FIG. 4;
3 is a motor, and 14 is an encoder, which correspond to the motor 24 and encoder 25 in FIG. 4, respectively.

A digital signal processor is a specialized microprocessor that can perform multiplication and addition at high speed, and was originally developed for digital filters and speech synthesis. This digital signal processor 10 includes an observer 10-1, an integrating circuit 10-2, a function generator 10-3, an arithmetic circuit 10-4, and performs processing as described below.

The DSPIO is a feature of the present invention, and when the target position Xc and the movement speed Vc at that time are given to the DSPIO from the host processor 1, the DSPIO reads the current position from the encoder 14 at each sampling time, The optimal 1llllilu (11th!
! In the example of J, the output voltage to the D/A converter 11) is calculated. At this time, DSPlo will perform the following calculations. In this case, if the controlled object consisting of the D/A converter 11, power amplifier 12, motor 13, and encoder 14 is expressed by the state equation (indicating the characteristics of the controlled object) shown in the following (Equation 11), the state The estimation equation of the observer based on the function as an observation device can be expressed by the following equation (2).

Z (k+1) = A-Z (k) +b-u −・
-=-=(1)7 (k+1)"C' ・Z (k+1
>Z-(21) where U: control input y: output value, which in this case is the positional deviation of 22.

Further, A, b, and C are determined based on the characteristics of the controlled object, where A is a matrix; b and c are vectors.

and C' is the transposed vector, and k represents the sampling time point.

For the state equation shown in equation (1) above, the observer estimation equation is constructed as follows.

Z (k+1) -A-Z (k) +b -u+f・
(This is the output value of the observer corresponding to y in ytem.

Moshi r is, You will be punished.

The operation of the present invention will be explained according to the flowchart of FIG.

(1) When the DSPro receives the target position Xc and the current moving speed Vc output from the host processor 1, it reads the output of the encoder 14 and learns the current position.

Then, the arithmetic circuit 10-4 calculates the positional deviation using the following equation (3).

Position deviation − Target position − Current position −・−−−1−−
(3) C) If this positional deviation is zero, it means that the target position has been matched, and therefore the next target position and moving speed are received from the host processor 1.

(3) If the position deviation is not zero, observer 1
Calculate the speed deviation by 0-1.

(4) Next is position bias! ! An integral amount Z3 of z2 is calculated by an integrating circuit 10-2. This is necessary to eliminate steady-state deviations.

Z 3 ”” f Z 2 d t
−−−−−−−−−−(4)(5) After obtaining all the state variables such as positional deviation 22, speed deviation Z1, and integral amount of positional deviation Z3, calculate using the following equation (5). The circuit 10-4 multiplies each state variable by the feedback coefficient determined by the optimal regulator theory and adds it to determine the optimal control amount, sends out this optimal control amount, and converts it into an analog value using the D/A converter 11. The signal is then amplified by the power amplifier 12 and the motor 13 is controlled.

u=-(kt ・Z+ +kz ・Z2 +3
1 Z3)・--111--------・-(5) Since calculations are executed at high speed in this manner, a high-speed and flexible digital control device for a motor can be provided.

In the above description, an example of a motor as a subject to be servo controlled has been described, but the present invention is of course not limited to only motors.

〔Effect of the invention〕

According to the present invention, since the servo system part is separated from the host processor and a dedicated DSP is used to execute servo control calculations at high speed, sampling time can be shortened, and a robust digital servo system that is resistant to external disturbances can be realized. You can build a control device. Furthermore, since the multiplication of feedback coefficients is performed using software, it is possible to flexibly handle controlled objects whose characteristics change during movement, such as robots.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIG. 2 is a block diagram thereof, FIG. 3 is a flow chart explaining the present invention in detail, and FIG. 4 is a conventional servo control device. In the figure, 1 is a host processor, 10 is a digital signal processor, 11 is a D/A converter, 12 is a power amplifier, 13 is a motor, and 14 is an encoder.

Claims (1)

[Claims] A target value output means for outputting a target value, a controlled object to be controlled so as to reach the target value, a state output means for the controlled object for outputting the state of the controlled object, and a means for outputting the state of the controlled object and the target value and the controlled object. A digital servo control device that compares the state of the body and controls the controlled body according to the difference, is equipped with a digital signal processor that has an observer function and an integral function, and the servo system part is separated from the host processor to control the servo system. A digital control device characterized in that calculations are performed by this digital signal processor.