JPH0732621B2 - Direct drive motor system - Google Patents

Description

The present invention relates to a direct drive motor system used for driving joints of a multi-joint type robot.

[Prior Art] A drive system using a DC motor and a speed reducer is often used in applications such as joint drive of an articulated robot that requires high torque at low speed. However, this drive system has problems such as the life of the brush of the DC motor and the speed reducer, or the maintenance of the lubricating oil.

As a solution to such problems, a magnetic inductor motor directly drives the robot (Direct Drive = DD).
There is a drive system that does. The motor used in such a drive system is a DD motor.

As a drive control circuit for a DD motor, there is one that feedback-controls the rotation position and rotation speed of the motor.

[Problems to be Solved by the Invention] In such a control circuit, in order to perform appropriate control, it is necessary to change the value of the control parameter according to the natural frequency of the motor or the load inertia.

However, in the conventional control circuit, when the load torque of the motor is unknown, it is impossible or extremely difficult to set the control parameter value.

The present invention has been made to eliminate such a problem, and an object of the present invention is to realize a DD motor system that can easily adjust the servo system even when the load inertia of the motor is unknown.

[Means for Solving Problems] The present invention also includes a motor unit, a drive circuit for driving the motor unit, an encoder unit for detecting rotation of the rotor of the motor unit, and a detection signal of the encoder unit. And a speed control unit that feedback-controls the rotation speed of the motor unit, a position control unit that feedback-controls the rotation position of the motor unit based on a detection signal of the encoder unit, the speed control unit and the position control unit. A tuning unit for adjusting the servo system, the position control unit, a gain table in which the values of the natural frequency and the load inertia of the motor unit and the optimum control parameter values corresponding to these values are associated, It has a test signal generating means for generating a known test signal as a position command signal, wherein the tuning unit has a plurality of stages of load inertia within a predetermined range. An inertia setting switch that is used to control the rotation of the motor unit by reading the optimum control parameter value from the gain table with the set value and the known test signal to the position control unit when the known test signal is applied to this test signal. It is a direct drive motor system characterized in that it has a monitor output terminal provided to take out the output of the position control section which has become a response signal and monitor the waveform of the taken out output.

[Examples] The present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an embodiment of a DD motor system according to the present invention.

In the figure, 100 is a motor unit, 200 is a drive circuit for driving the motor unit 100, 300 is an encoder interface (hereinafter referred to as encoder I / O) that detects rotation of the motor unit 100 by an encoder 300 _1.
F) 300 ₂ an encoder unit that outputs a detection signal via a signal, 400 a speed control unit that feedback-controls the rotation speed of the motor unit 100, 500 a position control unit that feedback-controls the rotation position of the motor unit 100, and 600 Is a tuning unit that adjusts the servo system of the speed control unit 400 and the position control unit 500.

The specific configuration of these is shown in FIG.

In the figure, the motor unit 100 is a three-phase inductor type motor in which a stator is arranged on the outside of the rotor.

In the drive circuit 200, 201 and 202 are coils L ₁ and L of the motor section.
₂ , a current detection circuit for detecting the exciting current flowing in ₂ , 203, 204 are current command values from the speed control unit 400 and the current detection circuits 201, 202
It is a subtractor that takes the difference of the detection current of. 205 is a power amplification circuit, which turns on the transistor of the excitation circuit 207 with the PWM signal generated by the PWM circuit 206 based on the signals from the subtracters 203 and 204.
When turned off, a three-phase sinusoidal current is passed through the motor so that the difference current between the subtractors 203 and 204 becomes zero. The current detection circuits 201 and 202 are
The exciting current of the coil is detected based on the voltage across the resistor r connected to the line 1 to which the coil is connected.

Next, the configuration of encoder section 300 will be described.

The encoder 300 _1, attaching the code plate and the translucent slits are provided for the light-transmitting slit and the origin detection for position detection at a sequence of a predetermined pitch to the rotor of the motor section 100, is projected to the slits, the slits It is an optical rotary encoder that detects the rotation of the rotor based on the transmitted light of.

The encoder I / F 300 ₂ converts the detection light of the encoder 300 ₁ into an electric signal and sends it to the speed control unit 400 and the position control unit 500.

Next, the configuration of the speed control unit 400 will be described.

In the speed control unit 400, 401 is a switch for switching between speed control and position control. This switch is connected to the contact h ₁ side for speed control, and connected to the contact h ₂ side for position control. 402 is an F / V converter, encoder I / F 300 ₂
The output signal of is converted into a speed signal.

403 is a signal from the switch 401 (which is the speed command value)
It is a subtractor that takes the difference between the signals from the F / V converter 402.

404 is a multiplying digital-to-analog converter (hereinafter referred to as MDA), whose gain is changed by a digital signal and which amplifies an analog input signal. The gain setting signal is given from the position control unit 500 or the tuning unit 600.

405 is a voltage control limiter (hereinafter referred to as VCL), which is an MD
Hold the A404 output at a certain upper or lower limit.

406 and 407 are MDA, which receive a signal from the VCL 405 and receive a current signal Isinθe according to a commutation control signal from the position control unit 500.
Or subtractor 2 with Isin (θe + 120 °) as current command value
Give to 03,204 (I is current).

Next, the configuration of the position control unit 500 will be described.

In the position control unit 500, 501 is a counter that generates and generates a position command signal based on a position command pulse signal and a rotation direction signal, and 502 is connected to the contact k ₁ side in the normal mode,
In the test mode, the switch is connected to the contact k ₂ side to which the test signal is given by the test signal generating means 502 ′.

Reference numeral 503 is a subtracter, which takes the difference between the signal from the switch 502 (which serves as a position command signal) and the signal from the position detecting means 504.

A position control unit 505 adjusts the gain of the MDA 404 based on the parameter read from the gain table 506 by a signal from the encoder I / F 300 ₁ or the tuning unit 600. The position control means 505 is an I-PD by software.
A third-order servo system that performs (integral, proportional, differential) operation is configured.

In the gain table 506, for example, as shown in FIG. 3, the load inertia J of the motor, the natural frequency fn of the motor, and the optimum control parameter values x ₁₁ , x ₁₂ , x ₁₃ corresponding to these values are associated with each other. It's a table. The gain table 506 includes tables for speed control and position control. Further, the speed control table and the position control table include a P operation (proportional operation) table and an I operation (integration operation) table.

507 is a multiplier 406, based on the signal from the encoder I / F 300 ₁ .
A commutation control unit that sends a signal to 407 to control the commutation of the motor, 508 is a D / A converter that converts the output of the position control unit 505 to digital / analog, and 509 is a sample of the output of the D / A converter 508.・ Sample to hold and send to tuning unit 600
Hold circuit (hereinafter referred to as S / H circuit).

When performing speed control, the switch 401 is connected to the contact h ₁ side, and the subtractor 403 calculates the difference between the analog speed input as the speed command value and the speed signal of the F / V converter 402. The gain of the MDA404 is set in the gain table 5 by the switches 601 and 602 described later.
It is set by the control parameter value read from 06.

When performing position control, the switch 401 is connected to the contact h ₂ side and the switch 502 is connected to the contact k ₁ side. Then, the position command signal from the counter 501 and the position detecting means 504
The subtractor 503 calculates the difference between the output signals of the. In the position control means 505, the switches 601 and 602 are used to read control parameters from the gain table 506, and the position control algorithm is used to adjust the gain of the MDA 404 using the control parameters.

Next, the configuration of the tuning unit 600 will be described.

In the tuning unit 600, 601, 602 are servo tuning switches. 601 is the natural frequency f within the specified range
This is a natural frequency setting switch that sets n in multiple stages. For example, with this switch, the natural frequency is 5-20Hz
The range is set in 16 steps.

Reference numeral 602 is an inertia setting switch for setting the load inertia J in a plurality of steps within a predetermined range.

When fn and J are set by these switches 601, 602, the optimum control parameter value corresponding to the set value is read from the gain table 506.

When performing position control using the switches 601 and 602, the position control unit 505 adjusts the gain of the MDA 404 based on the control parameter value read from the position control table. When performing speed control, the control parameters read from the speed control table are sent to the MDA 404 to adjust the gain.

603 is a switch for switching the switch 502, 604 is a switch 401
The switch 605 is a switch for switching the speed control and the position control to the integral operation or the proportional operation. By switching this switch, the integral operation table and the proportional operation table of the gain table 506 are used properly. When moving the robot arm with the DD motor, control is performed by integral operation when positioning the robot arm.
When an object is grabbed by the robot arm, control by proportional movement (compliance control) is performed.

Reference numeral 606 is a monitor output terminal for taking out the output of the position control unit 500 via the S / H circuit 402. This output is sent to a display device such as an oscilloscope for monitoring.

Reference numeral 607 is a pulse extraction terminal for extracting an incremental pulse signal via the up / down pulse generator 608.

Reference numeral 609 is an origin signal terminal for taking out the output of the photodiode that detects the light passing through the light transmitting slit for origin detection.

The outputs extracted from the pulse extraction terminal 607 and the origin signal terminal 609 are sent to a controller (not shown). The controller counts the command value of the rotation position of the motor from the output of the pulse extraction terminal 607, and detects the origin position from the output from the origin signal terminal 609.

BS is a data bus, and the encoder unit 300 and the speed control unit 4
00 to transmit signals between the position control unit 500 and the tuning unit 600.

Here, when the load inertia J of the motor is unknown, the switch 502 is connected to the contact k ₂ side and a known test signal is given to the position control means 505. At this time, the signal output from the position control unit 500 is output to the motor. Monitor using the terminal. And
Adjust the load inertia setting value with the inertia setting switch so that the distortion of the monitor waveform is eliminated.

The setting of Fn and J may be performed by an external controller instead of the switch.

[Effect] According to the present invention, the following effects can be obtained.

That is, when the load inertia of the motor is unknown, a known test signal is given to the position control means 550, and the output of the position control unit, which has become a response signal to the test signal, is taken out from the monitor output terminal 606 and monitored. The set inertia value can be adjusted with the switch 602 so that the distortion of is eliminated. As a result, the servo system can be easily adjusted even when the load inertia of the motor is unknown.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a DD motor system according to the present invention, FIG. 2 is a diagram showing a specific configuration example of FIG. 1, and FIG. 3 is an example of a gain table stored in a position control unit. It is a figure. 100: Motor section, 200: Drive circuit section, 300: Encoder section, 400: Speed control section, 500: Position control section, 50
2 '... Test signal generating means, 506 ... Gain table,
600: Tuning section, 602: Inertia setting switch, 606: Monitor output terminal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hitoshi Morimoto 2-932 Nakamachi, Musashino City, Tokyo Yokogawa Electric Co., Ltd. (72) Hideo Manshi Hideo Mansai 2-932 Nakamachi, Musashino City, Tokyo Horizontal Kawa Electric Co., Ltd. (72) Inventor Yasuhiko Muramatsu 2-9-32 Nakamachi, Musashino-shi, Tokyo Yokogawa Electric Co., Ltd. (72) Inventor Shotaro Shindo 2-9-32 Nakamachi, Musashino-shi, Tokyo Yokogawa Electric Within the corporation (56) References JP-A-61-204715 (JP, A)

Claims (1)

[Claims] 1. A motor unit, a drive circuit for driving the motor unit, an encoder unit for detecting rotation of a rotor of the motor unit, and a rotation speed of the motor unit based on a detection signal of the encoder unit. A speed control unit that performs feedback control, a position control unit that performs feedback control of the rotational position of the motor unit based on the detection signal of the encoder unit, and a tuning unit that adjusts the servo system of the speed control unit and the position control unit. Comprising, the position control unit, a gain table in which the values of the natural frequency of the motor unit and the load inertia and the optimum control parameter values corresponding to these values are associated, and a known test signal as a position command signal. The tuning unit sets a load inertia in a plurality of steps within a predetermined range and sets the gain tension at a set value. Inertia setting switch used to control the rotation of the motor unit by reading out the optimum control parameter value, and the position control that became a response signal to this test signal when the known test signal was given to the position control unit. A direct drive motor system having a monitor output terminal provided to take out the output of the unit and monitor the waveform of the taken out output.