JPH0819296A - Controller of motor - Google Patents

Abstract

PURPOSE:To prevent large vibration generated in a motor with simple constitution and operation by driving the motor in predetermined rotational speed change state with a driver, and reducing the drive current of the motor, as instructed in advance by an instruction means, in the rotational change state. CONSTITUTION:An instructive device 13 instructs the rotational speed change state of a motor 14, thus the rotational speed change state covering all operation periods of the motor 14 is set in CPU 16 in advance. In the case that there is an action speed having a possibility of causing a resonance point in the rotational speed change state of the motor 14, the instructive device 13 inputs a reduction command S1 into a controller so as to put the motor 14 in current reduction set state. Thereupon, CPU16 outputs a drive signal S2 to the motor driver 18 through an interface part 17. The motor driver 18 outputs a drive signal S3' to the motor 14, based on the drive signal S2 so as to reduce the drive current of the motor 14. Hereby, large vibration can be prevented in the motor.

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, and more particularly, it is used for an industrial robot (hereinafter referred to as a robot) and is provided with a teaching device such as a teaching pendant.
The present invention relates to a motor control device capable of presetting a rotational speed change state of a motor with the passage of time.

[0002]

2. Description of the Related Art Conventionally, as a drive source for an industrial robot, a two-phase stepping motor (hereinafter referred to as a motor) is used as an example.
Is used. This motor is used to translate or rotate the actuator part of the industrial robot in the X-axis direction and the Y-axis direction, for example.
Further, for the parallel movement and rotation of the robot, a CPU (Central Processing Unit) using a teaching device and a microcomputer provided in a driving device of the robot is used.
In addition, the movement amount of the parallel movement, the initial velocity at the time of movement, the steady velocity and the final velocity, or the rotation amount of the rotation, the initial velocity of the rotation, the steady velocity and the final velocity are taught and executed in advance.

It is known that, when such a robot is driven at a low speed, there is a speed region in which a large vibration called a resonance point is generated. The relationship between the pulse speed of the motor and the sensor output when the vibration of the motor is detected by the sensor is shown by the solid curve L1 in FIG. In order to prevent the occurrence of such a large vibration of the motor, conventionally, a biaxial motor is used, and a damper is attached to the shaft of the motor so that the large vibration is absorbed by the damper.

FIG. 6 shows a front view of a motor equipped with the damper. The motor 1 has a shaft 2 protruding from both sides of the motor 1, and a damper 3 is attached to one protruding end of the shaft 2 to fix the damper 3 to the shaft 2 with a set screw 4. The other projecting end of the shaft 2 serves as an output end for driving the actuator section and the like. Motor 1
Is supplied with a drive pulse via the lead wire 5. With the motor 1 having such a damper 3 attached, as shown in FIG.
The generation of the large vibration is prevented as indicated by the broken line L2.

In the motor 1 having the damper 3 attached as described above, there are problems that the number of parts required for the motor 1 is increased and the number of manufacturing steps is also increased. Further, although the resonance point may change depending on the installation environment of the motor, in order to prevent the occurrence of the large vibration, it is necessary to change the motor or the damper according to the installation environment. There is a problem.

[0006]

It is possible to prevent the occurrence of large vibrations in the low speed region of the motor by reducing the drive current of the motor in the low speed region. In the controller,
Only the configuration in which the rotation amount of the motor necessary for the parallel movement and rotation of the robot, the initial speed of rotation, the steady speed, the final speed, and the like are taught in advance is adopted. Therefore, it is difficult for the user of the robot to arbitrarily set the magnitude of the drive current of the motor provided in the robot, the period during which the drive currents of different magnitudes flow, and the like. Therefore, it has been difficult to realize large vibration in the motor with a simple configuration and operation.

The present invention has been made to solve the above problems, and an object thereof is to prevent the occurrence of large vibrations in a motor with a simple structure and operation. It is to provide a control device for a motor.

[0008]

A motor control device according to the present invention drives a motor in a predetermined rotational speed changing state,
The drive current of the motor is reduced in the rotation speed changing state,
After that, the drive unit that increases the drive current, and the drive unit,
Teaching means for inputting a reduction instruction for instructing the degree of reduction of the drive current in the rotational speed changing state,
Thereby, the above-mentioned object can be achieved.

In the present invention, the teaching means may input an increase instruction for increasing the drive current of the motor after the reduction instruction is input.

[0010]

According to the present invention, the motor control device includes the drive unit and the teaching means. The teaching means inputs to the drive unit a reduction instruction for instructing the degree of reduction of the drive current in the changing state of the rotation speed of the motor. The drive unit drives the motor in a predetermined rotational speed change state, and reduces the drive current of the motor in the rotational speed change state as previously taught by the teaching means. As a result, the drive current can be reduced in a speed region called a resonance point where a large vibration can be generated when the motor is operated at a low speed, so that the large vibration can be prevented. Since this action is realized by previously inputting the reduction instruction by the teaching means, the action can be realized with a simple configuration and operation.

Further, if the teaching means inputs an increase instruction for instructing an increase of the drive current of the motor after the input of the reduction instruction, the motor is in a state other than the rotational speed change state in which the drive current needs to be reduced. Since the drive current can be increased while the rotational speed is changing, the required rotational torque can be obtained from the motor.

[0012]

1 is a system diagram of an industrial robot (hereinafter referred to as a robot) 11 according to an embodiment of the present invention.
3 is a block diagram of the control device 12 used in the robot 11, and FIG. 3 is a front view of the teaching device 13 used in the robot 11. The robot 11 includes a two-phase stepping motor (hereinafter referred to as a motor) as an example of a drive source.
14 is used. The motor 14 is used to translate or rotate the actuator part of the industrial robot in, for example, the X-axis direction and the Y-axis direction. The control device 12 of the motor 14 includes a drive device 15 and a teaching device 13. By the teaching device 13,
The drive device 12 is taught in advance the necessary rotational speed change state of the motor 14.

The drive device 15 receives a signal from the teaching device 13 and is a CPU (central processing unit) 16 which is realized by using a microcomputer for performing various kinds of signal processing and the like, and an output from the CPU 16 drives a motor. Part 18
The interface unit 17 for transmitting to the motor and the motor drive unit 18 for outputting a drive signal for rotating the motor 14 at a predetermined rotation speed and rotation torque based on a signal from the interface unit 17.

As shown in FIG. 2, the CPU 16 has an input / output unit 19 for inputting / outputting signals to / from the teaching device 13, and a control unit 2 including a microprocessor.
0 and RO storing various data or programs for executing the predetermined operation of the control unit 20.
An M (read only memory) 21 and a RAM (random access memory) 22 that stores a signal or the like input from the teaching device 13 at any time are provided.

The teaching device 13, which is called a teaching pendant, is a remote operation device which is connected to the driving device 15 of the robot 11 and which starts / stops the robot 11 and teaches a moving path in the operation of the robot 11. Such a teaching device 13 includes a start switch 24, a stop switch 28, a numerical key group 26 for inputting various commands and numerical values,
A teaching mode key 25, an enter key 31 for confirming input data and commands, and a display device 23 for displaying the input commands are arranged. Further, the teaching device 13 of the present embodiment includes the current reduction key 29 for inputting the reduction instruction for instructing the reduction of the drive current in the rotational speed changing state of the motor 14, and the motor 1 after the input of the reduction instruction.
4 and a current increase key 30 for inputting a drive current increase instruction.

FIG. 4 is a block diagram showing the structure of the motor drive unit 18. The motor drive unit 18 is the CPU
Based on the rotation speed signal of the motor 14 from 16, the drive signal corresponding to this rotation speed signal is output, and the motor 1
4 based on the output signal from the CPU 16 that rotates the motor 4 at the rotation speed corresponding to the rotation speed signal and the reduction signal and the increase signal of the drive current from the CPU 16. And a current converter 32 that supplies the current.

The operation of this embodiment will be described below. In the present embodiment, first, the teaching device 13 causes the motor 14
Teaches the changing state of the rotation speed. This is performed by inputting the rotation speed of the motor 14 and the period during which this rotation speed is maintained. This teaching operation is performed by operating the teaching mode key 25 of the teaching device 13, inputting a predetermined numerical value by the numerical key group 26, etc., and operating the enter key 31. As a result, the rotation speed change state of the motor 14 over the entire operation period is set in the CPU 16.

When there is an operating speed range in which the above-mentioned resonance point may occur in the rotational speed change state of the motor 14, the current reduction key 29 is operated in the teaching mode state to move the teaching device 13 to the teaching device 13. In the current reduction setting state, the number key group 26 is used to input a current value reduced to a predetermined extent and a period required to maintain the reduced current value as the reduction instruction S1, and the enter key 31 is operated. Here, the degree of reduction of the current value is 1 to 100%. Next, the current increase key 30 is operated to restore the drive current of the motor 14 from the reduced current value to the initially set current value.

The rotation of the motor 14 is controlled while the rotation speed of the motor 14 thus changed is being changed. CPU1
6 outputs a control signal S2 to the motor drive unit 18 via the interface unit 17 based on the rotational speed change state of the motor 14 stored in the RAM 22. The motor control unit 18 outputs the drive signal S3 to the motor 14 to drive the motor 14 to rotate at the set rotation speed.

At this time, at the operation timing when the reduction instruction is input, the CPU 16 causes the interface unit 1 to operate.
A drive signal S2 for reducing the rotation speed of the motor 14 is output to the motor drive unit 18 via 7. The motor drive unit 18 outputs a drive signal S3 to the motor 14 based on the drive signal S2 to reduce the drive current of the motor 14. By thus driving the robot 11, it is possible to prevent the occurrence of the resonance point.

Since this operation is realized by inputting the reduction instruction in advance by the teaching device 13, the occurrence of the resonance point can be prevented by changing the motor or changing the damper as described in the prior art. It can be realized with a simple configuration and operation without requiring labor.

Further, since the teaching device 13 inputs the increase instruction for increasing the drive current of the motor 14 after the input of the reduction instruction, the motor 14 needs to reduce the drive current. The drive current can be increased in a rotation speed change state other than the normal rotation speed change state. As a result, the required rotation torque can be obtained from the motor 14.

[0023]

As described above, according to the present invention, the teaching means inputs the reduction instruction for instructing the degree of reduction of the drive current in the changing state of the rotation speed of the motor. The drive unit drives the motor in a predetermined rotational speed change state, and reduces the drive current of the motor in the rotational speed change state as previously taught by the teaching means.
As a result, the drive current can be reduced in a speed region called a resonance point where a large vibration can be generated when the motor is operated at a low speed, so that the large vibration can be prevented. Since this action is realized by previously inputting the reduction instruction by the teaching means, the action can be realized with a simple configuration and operation.

Further, if the teaching means inputs an increase instruction for instructing an increase of the drive current of the motor after the input of the reduction instruction, the motor is in a state other than the rotational speed change state in which the drive current needs to be reduced. Since the drive current can be increased while the rotational speed is changing, the required rotational torque can be obtained from the motor.

[Brief description of drawings]

FIG. 1 is a system diagram of an industrial robot 11 according to an embodiment of the present invention.

FIG. 2 is a block diagram of a CPU 16 of this embodiment.

FIG. 3 is a front view of the teaching device 13 of the robot 11 of the present embodiment.

FIG. 4 is a block diagram of a motor drive unit 18.

FIG. 5 is a graph illustrating a problem of the conventional technique.

FIG. 6 is a front view of a conventional motor.

[Explanation of symbols]

 11 Robot 12 Control Device 13 Teaching Device 14 Motor 15 Drive Device 16 CPU 18 Motor Drive Unit 20 Control Unit 29 Current Reduction Key 30 Current Increase Key

Claims (2)

[Claims] 1. A drive unit that drives a motor in a predetermined rotation speed change state, reduces a drive current of the motor in the rotation speed change state, and then increases the drive current; And a teaching means for inputting a reduction instruction for instructing a degree of reduction of the drive current in the rotational speed changing state. 2. The motor control device according to claim 1, wherein the teaching means inputs an increase instruction for increasing the drive current of the motor after the reduction instruction is input.