JPH10228319A - Controller for motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a motor controller improved at its positioning accuracy. SOLUTION: The controller for a motor 1 is provided with an F/V converter 3 for outputting a motor current speed signal as analog voltage based on the frequency of a current position pulse outputted from an encoder 2, a position control part 5 for outputting an analog voltage control signal for controlling the rotational position of the motor 1 proportionally to feedback based on a deviation (the number of correction pulses) between the number of objective command position pulses and the number of current position pulses and a motor rotational speed/feedback control part 7 for using the control signal as a speed command signal and controlling the rotational speed/feedback of the motor 1 based on the deviation from the speed detection signal. When the motor 1 is in a stopped state, a correction value is calculated by the means 2 based on (number of correction pulses)×(proportional gain of position control part) and analog voltage corresponding to the correction value is added to the output of the position control part 5 by an adder 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for performing feedback control of the rotational position and rotational speed of a motor using a position control loop and a speed control loop. More particularly, the present invention relates to a motor control device improved to improve positioning accuracy.

[0002]

2. Description of the Related Art In a motion system for controlling the movement of a robot arm, feedback control of the rotational position of a motor for driving the robot arm is performed by a motion controller, and feedback control of the rotational speed is performed by a servo driver. is there. Such a motion system is equipped with a motor control device.

FIG. 3 is a diagram showing a conventional configuration example of a motor control device of this kind. 3 is a motion controller, and S is a servo driver.

In FIG. 3, 1 is a motor to be controlled, 2 is an encoder for outputting a current position pulse which gives the current rotational position of the motor 1 by the number of pulses, and 3 is a motor 1 based on the frequency of the current position pulse. This is an F / V converter that outputs a current speed signal that gives the current rotation speed of the device as an analog voltage.
Reference numeral 4 denotes a subtractor for calculating a deviation between the number of pulses between the command position pulse for providing the target position and the current position pulse. It is a position control unit that outputs a control signal as an analog voltage signal. Reference numeral 6 denotes a subtractor for calculating a deviation between the control signal of the position control unit 6 and the analog voltage of the current speed signal of the F / V converter 3. Reference numeral 7 denotes a speed control unit that outputs a control signal for feedback-controlling the rotation speed of the motor based on the deviation obtained by the subtractor 6, and 8 denotes a speed control unit.
Is a drive circuit that drives the motor 1 based on the control signal output by the control circuit.

FIG. 4 is a Bode diagram of the motion controller M of FIG. In FIG. 4, Kp is a proportional gain of the position control unit 5. The motion controller M outputs an analog voltage corresponding to (deviation between the number of pulses between the command position pulse and the current position pulse) × Kp.

In the motor control device shown in FIG. 3, when an offset voltage is generated between the analog output voltage of the motion controller M and the analog input voltage of the servo driver S due to a temperature change, insufficient adjustment, or the like, the offset voltage is used. The motor rotates, and a deviation occurs between the number of command position pulses and the number of current position pulses. This deviation is defined as a steady-state deviation.
There is a difference between the analog voltage output when the motion controller M attempts to stop the motor and the analog voltage input when the servo driver S actually stops the motor. This difference is the offset voltage. FIG.
In the device described above, there is a problem that the positioning accuracy is reduced due to the occurrence of the steady-state deviation.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an apparatus for adding a positioning error to a position control unit by adding an analog voltage for correcting a steady-state error to an analog output voltage. It is an object of the present invention to realize a motor control device having improved motor performance.

[0008]

According to the present invention, there is provided an encoder for outputting a current position pulse which gives a current rotational position of a motor by the number of pulses, and a current rotational speed of the motor based on the frequency of the current position pulse. An F / V converter for outputting a current speed signal given by an analog voltage, and a feedback control of a rotational position of the motor by proportional control based on a deviation between a command position pulse for giving a target position and the number of pulses of the current position pulse. A position control unit that outputs a control signal for the analog voltage signal, and the control signal as a speed command signal,
A speed control unit that outputs a control signal for feedback-controlling the rotation speed of the motor based on the deviation between the control signal and the speed detection signal. Correction calculation means for calculating a correction amount from the number of correction pulses, which is a deviation between the number of pulses of the command position pulse and the number of the current position pulse, by (number of correction pulses) × Kp (Kp is a proportional gain of the position control unit); And an adder for adding an analog voltage corresponding to the correction amount to an output of the position control unit.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of the present invention.
1 that are the same as those in FIG. 3 are given the same reference numerals. M in FIG.
The part 1 is a motion controller. In FIG. 1, 2
Numeral 0 is a correction calculating means. When the motor 1 is in a stopped state, when the motor 1 is in a stopped state, the number of correction pulses is the difference between the number of pulses of the command position pulse and the number of pulses of the current position pulse. The correction amount is calculated by × Kp.
The number of correction pulses is set by the operator. An adder 21 adds an analog voltage of (number of correction pulses) × Kp to an output of the position control unit 5.

FIG. 2 is a Bode diagram of the motion controller M1. e is a steady state deviation. The motion controller M outputs an analog voltage obtained by adding (correction pulse number) × Kp to e × Kp.

The operation of the apparatus shown in FIG. 1 will be described. Analog output voltage of motion controller M and servo driver S
When an offset voltage is generated between the analog input voltage and the analog input voltage, the motor 1 rotates by an amount corresponding to the offset voltage, and the stationary deviation e between the number of pulses of the command position pulse and the current position pulse.
Occurs. The operator obtains the number of correction pulses from the difference between the command position pulse displayed on the screen and the number of pulses of the current position pulse, and sets the obtained correction pulse number in the correction calculation unit 20. The correction calculating means 20 calculates (correction pulse number) × Kp from the set correction pulse number. The adder 21 adds an analog voltage of (number of correction pulses) × Kp to the output of the position control unit 5. As a result, the offset calculation unit 20 outputs the offset voltage, and the position control unit 5
Becomes zero. For this reason, the steady-state deviation which is an input of the position control unit 5 also becomes zero. During the position control, the correction calculation means 20 always adds an analog voltage of (number of correction pulses) × Kp to remove a steady-state error.

[0012]

According to the present invention, when a steady-state error occurs in the rotational position of the motor, an analog voltage for correcting the steady-state error is added to the analog output voltage of the position control unit. Thereby, the positioning accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a Bode diagram of a motion controller of the apparatus of FIG. 1;

FIG. 3 is a diagram showing a conventional configuration example of a motor control device.

FIG. 4 is a Bode diagram of the motion controller of the device of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motor 2 Encoder 3 F / V converter 4,6 Subtractor 5 Position control part 7 Speed control part 20 Correction calculation means 21 Adder

Claims (1)

[Claims] An encoder for outputting a current position pulse for giving a current rotational position of a motor by the number of pulses, and a current speed signal for giving a current rotational speed of the motor as an analog voltage based on a frequency of the current position pulse. An F / V converter for outputting, and a control signal for feedback-controlling the rotational position of the motor by proportional control based on a deviation between a command position pulse for providing a target position and the number of pulses of the current position pulse. A position control unit that outputs a control signal as a speed command signal, and a speed control unit that outputs a control signal for feedback-controlling the rotation speed of the motor based on a deviation between the control signal and the speed detection signal. And a motor control device comprising: a motor; and a controller configured to calculate a number of pulses of the command position pulse and the current position pulse when the motor is stopped. A correction calculating means for calculating a correction amount from the number of correction pulses, which is a difference, by (number of correction pulses) × Kp (Kp is a proportional gain of the position control unit), and an analog voltage corresponding to the correction amount is calculated by the position control unit. A motor control device, comprising: an adder for adding to an output.