JPH0631656A - Positioning device - Google Patents

Abstract

PURPOSE:To provide a positioning device whereby a power supply of a motor can be stopped in the case of a runaway of a slider and of applying an abnormal load to a driving gear, in an industrial robot. CONSTITUTION:A device has a motor 14 for moving a slider 12 of an industrial robot 10 to a predetermined position, torque detecting means for detecting torque of the motor 14, position change amount detecting means for detecting a position change amount of the motor 14, memory means for storing a specified value of the position change amount in each torque and a control circuit 22 for taking out the specified value corresponding to the detected torque from the memory means and comparing this taken out specified value with the detected position change amount to interrupt a power supply circuit 24 of the motor 14 in the case that the detected position change amount is smaller than the specified value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning device for moving a movable body to a predetermined position such as an industrial robot.

[0002]

2. Description of the Related Art A positioning device used in an industrial robot is a current moving body that accurately grasps a distance from a reference point (or origin) when the moving body is moved to a target position. Is a device that informs the control device of the industrial robot of the position of. A position sensor is provided to detect the position of the moving body, and a signal from the position sensor detects how much the moving body has moved.

An example of this position sensor is an encoder attached to a motor that moves a moving body. The position of the moving body is detected by the rotation angle and the number of rotations of this encoder.

[0004]

However, in the positioning device provided with the position sensor having the above-mentioned structure, the position can be accurately grasped when the position sensor, that is, the encoder or the like is not operating normally. However, the moving body may run away and may be dangerous to the worker. Further, if an abnormal load is applied to the drive unit that drives the motor, continuing the operation as it is may lead to deterioration of the drive unit, which is dangerous.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention has been made in view of the above problems.
Provided is a positioning device capable of stopping the power supply of a motor when a moving body goes out of control or an abnormal load is applied to a drive device.

[0006]

A positioning device of the present invention is a positioning device for moving a moving body to a predetermined position, such as an industrial robot, and a motor for moving the moving body to a predetermined position. Torque detecting means for detecting the torque of the motor, position change amount detecting means for detecting the position change amount of the motor, storage means for storing a specified value of the position change amount for each torque, The specified value corresponding to the specified torque is fetched from the storage means, the fetched specified value is compared with the detected position change amount, and if the detected position change amount is smaller than the specified value, the motor power is shut off. It consists of means.

[0007]

[Operation] In the positioning device having the above structure, when the moving body is moved by the motor, the torque of the motor is detected by the torque detecting means. Further, the position change amount detecting means detects the position change amount of the motor. Then, a specified value corresponding to the detected torque is taken out from the storage means, the extracted specified value is compared with the detected position change amount, and if the detected position change amount is smaller than the specified value,
That is, when the position change amount does not move to the target position change amount, it is determined that an error has occurred in the positioning device or an abnormal load is applied to the motor, and the comparison means shuts off the power supply of the motor. To do.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below as applied to an industrial robot that moves a slider in a linear direction.

Reference numeral 10 denotes the industrial robot of this embodiment, which moves the slider 12 linearly in the X-axis direction.

Reference numeral 14 is an AC servo motor for moving the slider 12 via a belt. An encoder 16 is attached to the AC servomotor 14,
The rotation angle and the rotation speed of the C servo motor 14 can be detected.

Reference numeral 18 is a drive circuit for the AC servomotor 14. The drive circuit 18 is supplied with power from the power supply circuit 20 and rotates the AC servomotor 14 at a predetermined speed.

Reference numeral 22 is a control circuit for controlling the drive circuit 18. The control circuit 22 sends the A
A detection signal such as the number of revolutions of the C servo motor 14 is input,
The drive circuit 18 is feedback-controlled based on this. Further, the control circuit 22 detects the torque and the position change amount of the AC servomotor 14. This torque and position change amount detection will be described in detail below.

Reference numeral 24 is a teaching pendant for inputting a program for controlling the control circuit 22 and displaying the current state of the industrial robot. That is, the operator inputs a program using the teaching pendant 24, and the control circuit 22 controls the drive circuit 18 and the AC servomotor 14 based on the program. Instead of the teaching pendant 24, the display unit of the main body control unit of the industrial robot may be used to input a program or display the current state of the industrial robot.

Next, detection of torque and detection of position change amount in the control circuit 22 will be described.

Method for Detecting Torque The control circuit 22 outputs a torque command (current command) to the AC servo motor 14 to the drive circuit 18.
Then, according to this torque command, the AC servo motor 1
When 4 rotates, encoder 16 detects it and outputs a detection signal to control circuit 22. The control circuit 22 compares the torque command with the detection signal from the encoder 16 to determine whether or not the AC servomotor 14 has a torque output value equal to or higher than a certain value. Then, when the torque output value equal to or more than a certain value is obtained, the torque value of this torque command is set as the current torque value.

Detecting the amount of position change The rotation angle of the encoder 16 is stored from the detection signal of the encoder 16. That is, the position of the rotation angle of the encoder 16 at a certain time (hereinafter referred to as the previous position)
And the current position of the rotation angle of the encoder (hereinafter referred to as the current position) after a lapse of a predetermined time from the time of the previous position are compared, and the position change amount is calculated from the difference between the rotation angles of these motors.

Further, the control circuit 22 has a memory for storing a specified value of the position change amount for each torque value. This "specified value" is the slider-1 depending on the value of a certain torque.
When 2 moves, it refers to the minimum value of the amount of position change when moving normally without applying an abnormal load or the like. That is, when the detected position change amount does not reach the specified value, it is determined that an abnormal load or the like is applied to the slider-12.

In the industrial robot 10 having the above structure,
The operation of the positioning device will be described with reference to the flowchart of the control circuit 22 shown in FIG.

In step 1, the rotation angle (that is, position) from the encoder 16 is detected at regular intervals, and after the calculation output, a torque command is output. Then, according to the above method, it is determined whether the torque output value of the AC servomotor 14 is equal to or more than a certain value. finish.

In step 2, the previous position is compared with the current position by the detection signal from the encoder 16 by the above method, the position change amount is calculated, and the process proceeds to step 3.

In step 3, it is determined whether or not the amount of positional change is equal to or larger than a specified value stored in the memory. If it is equal to or larger than the specified value, it is determined that the normal state is reached, and the process ends. .

In step 4, it is judged that there is an abnormality, the power supply circuit 24 is turned off, and the process proceeds to step 5.

In step 5, an error is output to the teaching pendant 24, and the process ends.

As described above, the position change amount for each torque stored in advance in the memory is compared with the detected current position change amount. If the detected position change amount is equal to or less than the stored position change amount, It is judged that an abnormality has occurred in the AC servo motor 14 or an abnormal load is applied, and the power supply circuit 20 is turned on.
FF. Therefore, the drive circuit 18 and the power supply circuit 20 do not have an abnormal load and do not fail. Also,
The slider 12 does not run out of control.

[0025]

As described above, in the positioning device of the present invention, the comparison circuit compares the detected position change amount with the specified value stored in the storage means and corresponding to the detected torque, and detects the detected position change amount. If is smaller than the specified value, it is determined that an abnormal load is applied to the motor, or something is wrong with the circuit, and the motor power is cut off. Therefore, the moving body does not run out of control and does not break down due to an abnormal load on the circuit.

[Brief description of drawings]

FIG. 1 is a block diagram of an industrial robot showing an embodiment of the present invention.

FIG. 2 is a flowchart in the control circuit of the present invention.

[Explanation of symbols]

 10 ... Industrial robot 12 ... Slider 14 ... Motor 16 ... Encoder 18 ... Drive circuit 20 ... Power supply circuit 22 ... Control circuit 24 ... Teaching pendant

Claims (1)

[Claims] 1. A positioning device for moving a movable body to a predetermined position, such as an industrial robot, and a motor for moving the movable body to a predetermined position, and a torque for detecting the torque of the motor. A detection means, a position change amount detection means for detecting the position change amount of the motor, a storage means for storing a specified value of the position change amount for each torque, and a specified value corresponding to the detected torque from the storage means. A positioning device comprising: a take-out device, comparing the taken-out specified value with the detected position change amount, and shutting off the power of the motor when the detected position change amount is smaller than the specified value. .