JPS637183A - Servo motor controller - Google Patents

Abstract

PURPOSE:To stably and accurately control a servo motor by varying a current amplification factor in a current controller in response to a torque command signal to alleviate the load of a calculation. CONSTITUTION:In current automatic varying means 50, a deviation between a command speed signal and a present speed signal is obtained by a deviation unit 52 and fed to a binary code converter 54. An adaptive operation signal R responsive to the movement variation of a robot arm 40 from the converter 54 is fed to an analog switch 33 to control the amplification factor of a current amplifier 32. Accordingly, a current responsive to a torque command ta is easily obtained to be fed to a power amplifier 34, which amplifies it to a current level necessary to drive a servo motor 41 and supplies it to the motor 41.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a servo motor control device for moving a robot arm or the like.

(Prior art) A servo motor control device for a robot arm, etc. can be divided into three parts: a position control section, a speed control section, and a current amplification section, and a command (target) position of the robot arm is input from a host device. The position control unit calculates and determines the deviation between this command position and the current position signal of the robot arm.
This deviation is sent to the speed control section as a command speed. Note that the current position signal uses the output of an encoder provided on the robot arm. When the speed control section receives the command speed signal, it calculates the deviation between the command speed signal and the current position signal obtained by converting the current position signal, and sends this as a torque command signal to the current control section. . This current control section amplifies the torque command signal by a predetermined amplification degree and sends it to the servo motor to move the robot arm to the target position. By the way, if the above-mentioned control operation is performed using an 8-bit microcomputer, the arithmetic processing time will be insufficient, and no further arithmetic processing can be performed.

By the way, it is possible to apply adaptive control as a method of controlling the servo motor more stably and with high precision. However, in order to apply adaptive control, it is necessary to add arithmetic processing to change the control constants of the servo motor control device itself in response to changes in the characteristics of the controlled object, that is, the servo motor, which cannot be handled with an 8-bit microcomputer. It's gone.

(Problems to be Solved by the Invention) When trying to apply adaptive control as described above, it is necessary to use a higher-performance microcomputer, which results in more stable and high-precision control without changing the performance of the microcomputer. There is a need for a device that can control servo motors.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, it is an object of the present invention to provide a servo motor control device that can reduce the burden of calculation processing for servo motor control and can perform more stable and highly accurate control.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a servo motor control method that obtains a command speed signal from a command position signal for a robot arm, etc., and supplies it to a servo motor that moves the robot arm through a current control unit. To achieve the above object, the device is equipped with automatic current variable means for comparing the command speed signal and the current speed signal, obtaining an analog torque command signal from the comparison result, and varying the current amplification degree in the current control section. This is a servo motor control device.

(Function) By providing such means, for example, a command position signal is converted into a command speed signal, and a current position signal is converted into a current speed signal, and the signal is proportional to the deviation between these command speed signals and the current speed signal. Thus, the current amplification degree for the analog torque command signal in the current control section is varied.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a servo motor control device, including a position control 1aI3io, a speed control section 20, and a current control section 30.
It consists of The position control unit 10 calculates the deviation between the command position signal ma for the robot arm 40 as a controlled object and the current position signal ll1b of the robot arm 40 using a deviation device 1), sends it to the deviation counter 12, and calculates the count value of the deviation counter 12. The current position signal mb is sent to the speed control unit 20 as a command speed signal "a."The current position signal mb is output from a pulse encoder 42 that detects the actual position to which the robot arm 40 is driven by the servo motor 41. Current automatic variable means 50 whose pulse output will be described later
The count output of the current position counter 51 is used. The speed control unit 20 converts the command speed signal fa into a D/A
The (digital/analog) converter 21 converts the data into analog and sends it to the deviation device 22.
The pulse output of 2 is converted into a voltage signal by an F/V (frequency/voltage) converter 23 and sent to the deviation device 22. The deviation output of the deviation device 22 is sent to the speed amplifier 24, which performs an integral process to eliminate the speed deviation, that is, to follow the speed, and sends the torque command signal ta to the current control section 30. It is configured to send. The N flow control unit 30 supplies a current equal to the torque command signal [a to the servo motor 41, and the torque command signal t
a is sent to a current amplifier 32 through a deviation device 31. This current amplifier 32 has a configuration in which the degree of amplification is variable by turning on and off an analog switch 33.

The specific circuit configuration is as shown in FIG. 2, in which resistors R1 to R are arranged at each switch 51 to S port of the analog switch 33 so as to have a resistance value ranging from a large resistance value to a small resistance value.
These resistors R1 to Rn are connected in common and connected to one input terminal of an operational amplifier Q via a resistor Ra. - On the other hand, the switches S1 to sn are commonly connected and connected to the output terminal of the operational amplifier Q. The current output from the current amplifier 32 is supplied to the servo motor 41 through the power amplification section 34. In addition,
A current tb supplied to the servo motor 41 is detected and fed back to the deviation device 31.

Now, the automatic current variable means 50 converts the command position signal ma into a command speed signal, converts the current position signal @lb into a current speed signal, calculates the deviation between these command speed signals and the current speed signal, and calculates the deviation between these command speed signals and the current speed signal. proportionally analog torque command signal t
It has the function of varying the current amplification degree with respect to a. In other words, this automatic current variable means 5o performs an adaptive operation that automatically varies the control constant in the servo motor control device, that is, the current amplification degree of the current amplifier 32, according to the change in the operation of the robot arm 40 using the command position signal +++a and the current position signal mb. Its function is to send out signals.

The specific configuration is as follows. That is, a command speed conversion unit 51 converts the command position signal 1a into a command speed signal and sends it to the deviation device 52, and a command speed conversion unit 51 converts the current position signal mb from the current position counter 51 into a current speed signal and sends it to the deviation device 52. It is composed of a current speed converter 53 and a binary converter 54 that converts the g difference output of the deviation device 52 into a binary signal and sends this binary signal to the analog switch 33 as an adaptive operation signal R. When the deviation output of the deviation device 52 is large, the amplification degree of the N-current amplifier 32 becomes high, and when the deviation output is small, the amplification degree of the current amplifier 32 becomes low.By the way, part A in FIG. 1, that is, the position control The section 10 and the current automatic variable means 50 are configured to be programmed by a microcomputer, and the negative section B is configured by hardware.Therefore, the arithmetic processing of the microcomputer is performed by the position control section 10 and the current control section 10. These are the various functions of the automatic variable means 50.

Next, the operation of the apparatus configured as described above will be explained. The command position signal ma is taken into the position control section 10, and the pulse output of the pulse encoder 42 is counted by the current position counter 51, and the count value is taken into the position IIIwJ section 10 as the current position signal a+b. This position control section 10 counts the deviation between the command position signal 1a and the current position signal ib using a deviation counter 12, and sends the counted value to the speed control section 20 as a command speed signal fa. This speed control section 20 converts the command speed signal fa into an analog signal and converts the frequency of the pulse output of the pulse encoder 42 into a voltage signal to find the deviation between these command speed signals and the current speed signal rb. Then, in accordance with this deviation, an analog torque command signal [a is determined by the speed amplifier 24 and sent to the current control section 30.

On the other hand, in the automatic current variable means 50, the command speed converter 5
1 receives the command position signal ma and converts it into a command speed signal,
At the same time, the current speed converter 53 converts the current position counter 5
The current position signal a+b from 1 is received and converted into a current speed signal. Then, the deviation between the converted command speed signal and the current position signal is determined by the deviation device 52 and sent to the binary code conversion section 54. In this way, the adaptive operation signal @R corresponding to the movement change of the robot arm 4o is sent from the binary code converter 54 to the analog switch 33.
will be sent to. Note that this adaptive operation signal R is sent out in synchronization with the command position signal ll1a. Thereby, if the deviation output of the deviation device 52 is large, the switches 31 to sn connecting high resistance among the analog switches 33 are closed, and the amplification degree of the current amplifier 32 is increased. Furthermore, if the deviation output of the deviation device 52 is small, the switches S1 to sn connecting the low resistances of the analog switches 33 are closed, and the current amplifier 3
The amplification degree of 2 becomes lower. Therefore, a current corresponding to the torque command ta is easily obtained and sent to the power amplification section 34, and from the power amplification section 34 it is amplified to a current level necessary to drive the servo motor 41 and is supplied to the servo motor 41. Ru. Thus, the robot arm 40 moves according to the command position signal.

In this way, in the above embodiment, the command position signal ll
1a into a command speed signal, and converts the current position signal Ilb into a current speed signal, and outputs an analog torque command signal [with respect to a] in the current control section 30 in proportion to the deviation between these command speed signals and the current speed signal. Since the current amplification degree is calculated and variable, it can be controlled by a servo motor! l
Adaptive control that varies the current amplification degree of the torque command as the opening constant of the I device can be applied, and the drive of the servo motor 41 can be controlled stably and with high precision. And the current control section 30
By using the hardware configuration, the calculation processing by the microcomputer can be performed only by the knowledge of the position control unit 10 and the automatic current variable means 50, and the microcomputer can be
Bits can also be used.

Therefore, adaptive control can be applied to the control of the servo motor 41 without changing the 8-bit microcomputer to a high-performance one.

Note that the present invention is not limited to the above-mentioned embodiment, and may be modified without departing from the spirit thereof. For example, in the above embodiment, the amplification degree of the current amplifier 32 is varied in the direction of eliminating the deviation between the commanded speed and the current speed, but the current amplifier 32 is changed depending on the deviation between the commanded position and the current position instead of the speed.
It may be configured such that the amplification degree of 2 is variable.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a servo motor control device that can reduce the burden of calculation processing for servo motor control and can perform opening and opening more stably and with high precision.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of a servo motor control device according to the present invention, and FIG. 2 is a partially specific block diagram of a 'R current control section. 10... Position control section, 20... Speed control section, 30.
...Current control unit, 32...Current amplifier, 33...Analog switch, 4o...Robot arm, 41...
・Servo motor, 42...Pulse encoder, 50・
・・Current automatic variable means, 51 ・・Command speed converter, 5
3... Current speed converter, 54... Binary code converter.

Claims (2)

[Claims] (1) In a servo motor control device that obtains a command speed signal from a command position signal for a robot arm, etc. and supplies it to a servo motor that moves the robot arm through a current control unit, the command speed signal and the current speed signal are compared. . A servo motor control device comprising automatic current variable means for obtaining an analog torque command signal from the comparison result and varying the current amplification degree in the current control section. (2) The automatic current variable means converts the command position signal into a command speed signal, converts the current position signal into a current speed signal, determines the deviation between these command speed signals and the current speed signal, and calculates the deviation proportional to this deviation. Claim (1) sends out an adaptive operation signal that varies the current amplification degree in the current control section.
The servo motor control device described in .