JPH07141031A - Analog servo driver - Google Patents

Abstract

PURPOSE:To control the rotating position and rotating speed of a motor with a low-priced analog servo system. CONSTITUTION:The analog servo driver is composed of a control parameter calculating means 1 for calculating control parameters based on various kinds of information, analog generators 2, 3 and 4 for outputting PWM waves based on the control parameters from the calculating means 1, and analog switches 5, 6 and 7 installed on the output side of respective analog generators, and a power drive part 14 of a motor 16 is controlled by analog servo.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analog servo driver for controlling a servo motor that rotates based on a command, and more particularly to a driver for improving control performance by changing various control parameters.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram showing a conventional servomotor control device disclosed in Japanese Patent Laid-Open No. 2-115970. In the figure, 11 is a position differentiator that takes the difference between a position command value and a position feedback signal, 12 is a speed differentiator that takes the difference between a speed command value and a speed feedback signal, and 13 is a current command value and a current feedback signal. Current difference device for calculating the difference between
5 is a current detector, 16 is a motor, 17 is an encoder, 1
Reference numeral 9 is a position compensation unit, 21 is a current compensation unit, 47 is a control parameter calculation unit, 48 is a control parameter setting unit, and 49 is a speed compensation unit. Here, the position differencer 11 and the speed differencer 1
2, current difference unit 13, position compensation unit 19, speed compensation unit 4
9, the current compensation unit 21, the control parameter calculation unit 47, and the control parameter setting unit 48 are software, and constitute a digital servo system.

In the above structure, the position compensator 19 inputs the position deviation between the position command and the position feedback signal and outputs the speed command. The speed compensator 49 inputs the difference between the speed command and the speed feedback signal and outputs a current command. The current compensator 21 inputs the difference between the current command and the current feedback signal, outputs a motor control signal, and drives the motor 16 via the power drive unit 14. The current feedback signal is detected by the current detector 15, and the position feedback signal and the velocity feedback signal are detected by the encoder 17, respectively, and are input via a feedback circuit (not shown).

Since this control device employs a digital servo system in which the rotational position and rotational speed of the motor and the current flowing through the motor are controlled by software, the control parameter calculation unit 47 calculates the control parameter according to the position deviation. The control parameter setting unit 48 sets this control parameter in the speed compensating unit 49, thereby improving the response, stability, accuracy, etc. of the servo system. That is, the speed compensator 49 is set to a control parameter that can output a current command value suitable for a stop during a stop, and the speed compensator 49 is set to a control parameter that can output a current command value suitable for a high speed move during a high speed movement. .

[0005]

The above-mentioned conventional servo motor control device is constituted by a digital servo system by software. Therefore, when the position compensating unit 19, the speed compensating unit 49, and the current compensating unit 21 are of an analog servo system composed of analog circuits, and compared with the case where the analog servo system is configured with equivalent control parameters,
Performance deteriorates due to the effects of sampling and dead time, and the effects of quantization. In order to suppress these effects,
There is a problem that the CPU has to be increased in speed and function, and digital circuits around the CPU, which become large in scale, must be integrated by G / A or the like, resulting in a significant increase in cost.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an analog servo driver of an analog servo system capable of changing a control parameter according to a command, a rotation state, a load state and the like.

[0007]

FIG. 1 shows a basic configuration of the present invention, in which 1 is a control parameter calculating means, which takes in various kinds of information such as a rotation command and a rotation state, and performs each control according to the operating condition of a motor. Determine the parameters. 2, 3, 4 is PW
M generator, 5, 6 and 7 are analog switches (analog S
W), 8 is an analog control compensator as a position compensator, 9
Is an analog control compensator as a speed compensator, and 10 is an analog control compensator as a current compensator. Also, 11
Is a position difference device that takes the difference between the position command value and the position feedback signal, 12 is a speed difference device that takes the difference between the speed command value and the speed feedback signal, and 13 is current that takes the difference between the current command value and the current feedback signal Differentiator, 14 is a power tribe section, 15 is a current detection section, 16 is a motor,
Reference numeral 17 is an encoder.

In the above structure, the position compensator 8 inputs the position deviation between the position command and the position feedback signal and outputs the speed command. The speed compensator 9 inputs the difference between the speed command and the speed feedback signal and outputs a current command. The current compensating unit 10 inputs the difference between the current command and the current feedback signal, outputs a motor control signal, and drives the motor 16 via the power drive unit 14. The current feedback signal is detected by the current detector 15, and the position feedback signal and the velocity feedback signal are detected by the encoder 17, respectively, and are input via a feedback circuit (not shown).

In the operating state of the motor controlled as described above, various information such as the rotation command and the rotation state of the motor rotating based on the command are fetched by the control parameter calculating means 1 and are excellent. Optimal control parameters are determined according to various information so as to obtain the rotation state.
The determined control parameters are the respective PWM generators 2,
3 and 4, and the PWM generators 2, 3, and 4 generate respective PWs in which the values of the respective control parameters are associated with the duty.
Generate M waves. Here, the carrier frequency of the PWM wave is a frequency f ₀ sufficiently higher than the cutoff frequency of each loop of position, velocity and current. And each PWM wave is an analog SW5.
It is input to the control terminals of 6 and 7, and the input terminal and the output terminal are turned on by the High level or Low level of the PWM wave.
It is turned off again. The input of each analog SW 5, 6, 7 is the output of each analog control compensator 8, 9, 10 that compensates for the difference between the command value and the feedback signal. Therefore, the output of each of the analog SWs 5, 6 and 7 is set to an arbitrary value of 0 to 100% with respect to the output of each of the analog control compensation units 8, 9, and 10 according to the duty of each PWM wave of 0 to 100%. Can be taken.

In FIG. 1, PWM generators 2, 3, 4 and analog SW 5, are provided for position control, speed control, and current control, respectively.
Although a combination of 6 and 7 is incorporated, in the present invention, it is sufficient that there is a combination of a PWM generator and an analog SW in at least one place, and it is applicable to any one of position control, speed control and current control. Good.

[0011]

[Embodiment 1] FIG. 2 is a block diagram showing the overall configuration of Embodiment 1 of the present invention, FIG. 3 is a circuit diagram within the chain line of FIG. 2, and FIG.
Of the software program processed by the CPU 23a in FIG.
FIG. 6 is a characteristic diagram showing an example of the characteristics of the position deviation and the speed compensation gain set in FIG. In FIG. 2, reference numeral 18 is a control parameter calculation means including a PWM generator, and the position deviation is input as information. Reference numeral 19 is a position compensator, 20 is a speed compensator including an analog SW, 21 is a current compensator, and 22 is a speed detector that converts the signal of the encoder 17 into f / v and outputs a speed feedback signal. Elements 11 to 17 are the same as those in FIG. 1, and are designated by the same reference numerals.

In FIG. 3, reference numeral 24 is a deviation counter,
It corresponds to the position differentiator 11 in FIG. 25 is D / A
Converter, 26a is an operational amplifier, 26b is the resistance the resistance value r _1, 26c is a resistor the resistance value r _2, they correspond to the position compensator 19 in FIG. 2. 27a is an operational amplifier, 27b is a resistor having a resistance value r ₃ , 27c is a resistor having a resistance value r ₄ , 27d is a resistor having a resistance value r ₅ , 27e is a capacitor having a capacitance c ₁ , 27f is a resistor having a resistance r ₆ , and 27g is an analog. SW, and these correspond to the speed differentiator 12 and the speed compensator 20 including the analog SW in FIG. 23a
Is a CPU, 23b is an I / F, 23c is a ROM, 23d is a RAM, 23e is a PWM generator, and 23f is a counter, which correspond to the control parameter calculation means 18 including the PWM generator in FIG. Position deviation is entered. Since 23a to 23f are composed of inexpensive microcomputers, the microcomputers 23a to 23f are integrated together.
And

In FIG. 4, 28 is a program for reading the value of the deviation counter 24 via the I / F 23b, and 29 is the control parameter value of the speed compensator 20 calculated from the value of the deviation counter 24 to determine the duty of the PWM output. A program, 30 is a program for outputting a PWM wave from the PWM port.

The rotation operation of the motor in this configuration is the same as that of the conventional device and the basic configuration shown in FIG. 1, and the difference between each command value of position / speed / current and each feedback signal is calculated and each compensation is applied. Then, the motor drive amount is determined and applied to the motor. FIG. 5 shows an example of the characteristics of position deviation and speed compensation gain.
The gain is set low so that the motor can be stopped smoothly without overrun when stopped. When moving at high speed with many deviations, the gain is set high so that uneven rotation can be suppressed as much as possible.

In the above configuration, as shown in FIG. 4, when the position command to the motor disappears, that is, when a stop command is issued and the motor comes to a stop, the position deviation becomes smaller. The output of the deviation counter 24 is taken into the microcomputer 23 as a position deviation value. (Operation 28 in FIG. 4). The fetched position deviation value determines the control parameter according to the characteristic shown in FIG. 5 (operation 29 in FIG. 4). Since the position deviation is small, the control parameter becomes small. The PWM duty is determined according to the control parameter, and the PWM wave is output from the microcomputer 23 (see FIG. 4).
30). Since the duty of the PWM wave becomes smaller, the OFF time of the analog SW 27g becomes longer than the ON time of the analog SW 27g, and the apparent gain of the operational amplifier 27a becomes lower. The response of is slow rather than oscillatory, and the motor stops smoothly without overshooting.

There is a large amount of position deviation during high-speed movement where the position command is large and constant. The position deviation is captured by the microcomputer 23,
The duty of the PWM wave is determined according to the characteristics shown in FIG. Since there are many position deviations, the duty becomes large, and the analog SW 27g remains ON for a long time. Then, the apparent gain of the operational amplifier 27a becomes so high as not to oscillate, the frequency characteristic of the speed control system is extended, and uneven rotation can be suppressed.

In the illustrated example, the characteristics of the position deviation and the velocity compensation gain have been described with reference to FIG. 5, but the characteristics may be those suitable for the purpose of improving the performance, and are not limited to those in FIG. . Further, the change of the speed compensation gain has been described, but the gain of another compensating unit may be changed.

In this embodiment, even if the analog servo system is adopted, the control parameters can be changed at any time according to the motor driving state, so that a high performance system can be constructed.

[0019]

[Embodiment 2] FIG. 6 is a block diagram showing the overall configuration, and FIG. 7 is an operation flow during automatic adjustment. In FIG. 6, 11 to
Reference numeral 17 is the same element as that of the first embodiment and is given the same reference numeral. Reference numeral 31 is a personal computer I / F circuit including a counter for converting data so that a command pulse, the number of pulses of feedback, and a pulse frequency as various information can be taken into the personal computer 32. The personal computer 32 incorporates a block modeling the entire system and a program for designing each control parameter of the position compensator 36, the speed compensator 37, and the speed detector 39 that match the moving object 40. 33, 34,
Reference numeral 35 is a PWM generator having a built-in memory for loading control parameters on the PWM wave as duty information. Three
6 is a position compensator including an analog SW, 37 is an analog S
A speed compensator including W, and 39 is a speed detector including an analog SW. 38 is a current compensator. Moving object (load)
40 is moved by utilizing the rotation of the motor connected to the motor 16.

In FIG. 7, reference numeral 41 is an operation of the personal computer 32 for initializing the system model, and 42 is an operation for actually inputting a pulse as a position command to rotate a motor in the system. The reference numeral 43 captures the command pulse / feedback pulse into the personal computer 32 using the I / F circuit 31,
This is an operation of the personal computer 32 that compares a state in which the motor actually rotates in action 42 with a state in which the rotation of the motor is virtually estimated by the system model by various data processing. Four
4 is the operation of the personal computer 32 that corrects the model of the controlled object such as the motor 16 and the moving object 40, and 45 is the position compensator 36, the speed compensator 37, and the speed detector 39 that make the modified system model stable and high response. This is the operation of the personal computer 32 to be designed. Reference numeral 46 determines whether or not the position compensator 36, the speed compensator 37, and the speed detector 39 need to be modified, and if necessary, the position compensator 36 and the speed compensator via the PWM generators 33, 34, and 35. 37, the speed detector 39 is modified, and the operations 42 to 45 are repeated. If the adjustment is completed and no correction is necessary, each control parameter is written in the ROM in the PWM generators 33, 34, 35 to complete the adjustment. is there.

Also in this embodiment, the rotation operation of the motor is
Similar to the conventional device and the basic configuration shown in FIG. 1, the difference between each command value of position / speed / current and each feedback signal is taken for each compensation to determine the motor drive amount and apply it to the motor. There is.

Next, automatic adjustment of the control parameters before the motor operation will be described. First, the personal computer 32 is used to initialize blocks that model the transfer characteristics of the entire system (11 to 17 and 36 to 40). The models of the position compensator 36, the speed compensator 37, and the speed detector 39 are the actual position compensator 36, the speed compensator 37, and the speed detector 3.
In accordance with the control parameters of 9,
The model is modeled assuming that it is in an unloaded state before being attached (operation 41 in FIG. 7). After that, the position command pulse is input, the motor is rotated to drive the actual system, and the position command pulse is taken into the personal computer 32 to calculate how the modeled block behaves. The actual system is driven while the adjustment is incomplete, and its behavior is captured by the personal computer 32 as an output pulse of the encoder 17 (operation 42 in FIG. 7). A feature amount is extracted from the captured actual behavior and is compared with the feature amount calculated using the modeled block (FIG. 7).
43). Based on the comparison of the feature amounts, the model of the moving object 40 is mainly estimated and modified (see operation 4 in FIG.
4) Determine the optimum control parameters for the position compensator 36, speed compensator 37, and speed detector 39 for the corrected model (operation 45 in FIG. 7). If the position feedback signal is separated from the position command and the control parameters need to be corrected, the PWM generators 33, 34, 3
Each control parameter value is written in each memory in 5, and operation 42 to operation 45 are repeated. If the position command and the position feedback signal substantially match and the control parameter does not need to be corrected, the adjustment ends (operation 4 in FIG. 7).
6). After the automatic adjustment is completed, the personal computer 32 is removed from the system and the motor is operated.

Even if the analog servo system is adopted in this embodiment, the control parameters can be changed, so that the control parameters can be automatically adjusted without relying on human experience.

[0024]

As described above, in the present invention, the control parameter can be easily changed even if the low-cost analog servo system is adopted.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of the present invention.

FIG. 2 is a block diagram showing an overall configuration of a first embodiment of the present invention.

FIG. 3 is a circuit configuration diagram within a chain line in FIG.

FIG. 4 is a flowchart of a software program processed by the CPU in FIG.

FIG. 5 is a characteristic diagram of a position control deviation and a velocity compensation gain set in a parameter calculation means.

FIG. 6 is a block diagram showing an overall configuration of a second embodiment of the present invention.

FIG. 7 is an operation flowchart during automatic adjustment according to the second embodiment.

FIG. 8 is a block diagram showing a conventional servo motor control device.

[Explanation of symbols]

 1 Control Parameter Calculation Means 2, 3, 4 PWM Generator 5, 6, 7 Analog Switch 8, 9, 10 Analog Control Compensation Section

Claims (1)

[Claims] 1. An analog servo driver for controlling a rotation position and a rotation speed of a motor, wherein a control parameter calculating means for calculating a control parameter and a PW based on the control parameter obtained by the control parameter calculating means.
An analog servo driver, comprising: a PWM generator that outputs M waves; and an analog switch that is provided in an output portion of various controlled variables.