JP2001212778A - Controller for robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller for a robot, capable of reducing the moving amount of a servo motor from the generation of a state to stop the rotation of the servo motor to the stop of the rotation of the servo motor without limiting (reducing) the rotational speed of the servo motor. SOLUTION: When a power source of a servo motor 15 is turned off or when an emergency switch 23 is turned on, an electric signal is given to a pulse oscillator 11 and a deviation counter 12 by an electric circuit constituted of a power source monitor relay 21, transistors 22, 24, an emergency stop switch 23, an OR circuit 26, a DC power source of 24 V for control, and a GND, supply of a pulse signal for commanding the rotational angle of the servo motor 15 is stopped, an accumulated pulse of the deviation counter 12 is cleared, and the rotation of the servo motor 15 is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot controller for rotating and stopping a servo motor, which is a driving source of the robot, by a servo mechanism.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor manufacturing apparatus, a wafer transfer robot is controlled by a servo mechanism. In other words, a servomotor is used as a drive source, and the rotation speed and rotation angle of the servomotor are fed back so that the rotation speed and rotation position of the servomotor always coincide with the target value, thereby changing the target value. I always follow.

As shown in FIG. 5, when the power of a servomotor is turned off during operation, the wafer transfer robot detects the power-off of the servomotor with an alarm in a servo driver, thereby providing dynamic control. The brake is operated to set the rotation speed of the servo motor to "0", and thereafter, the holding brake (mechanical brake) is operated to stop the operation of the wafer transfer robot instantaneously. That is, in the wafer transfer robot, the operation of the wafer transfer robot is instantaneously stopped by control different from the above-described servo mechanism.

[0004]

However, in order to detect the power off of the servo motor by the servo alarm, the time required for the voltage to drop in the servo driver ("voltage drop time" in FIG. 5) is reduced. I had to spend it. Therefore, the servo motor continues to rotate at the rotation speed when the power of the servo motor is turned off until the “voltage drop time” in FIG. 5 elapses.

Further, even if the dynamic brake is operated after the "voltage drop time" in FIG. 5 has elapsed, the rotational speed of the servomotor does not immediately become "0" due to the inertia force of the servomotor. The motor continued to rotate while decelerating until its rotation stopped (FIG. 5).
"Motor deceleration time").

That is, the servo motor continues to rotate at the rotation speed when the power supply of the servo motor is turned off until the "voltage drop time" in FIG. 5 elapses, and the "motor deceleration time" in FIG. 5 elapses. Until the rotation of the servo motor is continued, the rotation is continued while decelerating until the rotation speed becomes “0”. Therefore, even if the power of the servo motor is turned off, the rotation of the servo motor cannot be stopped instantaneously.

Therefore, as long as the operation of the wafer transfer robot is stopped instantaneously according to the prior art, the servomotor moves from the time when the power of the servomotor is turned off to the time when the rotation of the servomotor stops (refer to FIG. )) At a certain level or more, and unless the rotational speed of the servomotor is limited (slowed) and the inertial force of the servomotor is reduced, the “motor movement amount” in FIG. I couldn't keep it small. On the other hand, in the field of semiconductor manufacturing equipment, there is a tendency for miniaturization in recent years, so that the “motor movement amount” in FIG. There is an increasing demand for a reduction in the “motor movement amount”.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made to solve the above-mentioned problem. It is an object of the present invention to provide a robot controller which can further reduce the rotation speed of the robot without limiting (slowing) the rotation speed of the servomotor.

[0009]

According to a first aspect of the present invention, there is provided an apparatus for controlling the rotation and stop of a servomotor which is a drive source of a robot, by controlling a target position command value and a servomotor of the servomotor. In a robot controller that performs based on a deviation from a current position detection value fed back from a position sensor, the robot includes stop command generation means for giving a stop command, and when the stop command is given from the stop command generation means, The rotation of the servomotor is stopped by stopping the supply of the target position command value and clearing the deviation.

According to a second aspect of the present invention, in the robot control device according to the first aspect, the stop command generating means monitors a power supply of the servomotor, and when the power supply is turned off. The stop command is given to the user. According to a third aspect of the present invention, in the robot control device according to the first aspect,
The stop command generating means includes an emergency stop switch, and when the emergency stop switch is turned on,
Giving the stop command.

According to a fourth aspect of the present invention, in the robot control apparatus according to any one of the first to third aspects, the robot is a wafer transfer robot.

In the robot control apparatus according to the present invention having such features, the rotation / stop of the servomotor, which is the drive source of the robot, is determined by the target position command value and the current position detection value fed back from the servomotor position sensor. And based on the deviation.

When a situation occurs in which the rotation of the servomotor should be stopped while the robot is operating, a stop command is given from the stop command generating means, and the supply of the target position command value is stopped. And a deviation between the current position detection value fed back from the position sensor of the servomotor and the rotation of the servomotor is stopped.

That is, in the robot control apparatus of the present invention, when a situation in which the rotation of the servomotor should be stopped occurs, the stop command generating means is operated to make the current position of the servomotor coincide with the target position. Since the rotation of the servomotor is stopped during the position control of the servo mechanism, the rotation of the servomotor can be stopped at the moment when the rotation of the servomotor needs to be stopped. Therefore, the rotation speed of the servo motor is not set to “0” by the dynamic brake during the period from the occurrence of the situation where the rotation of the servo motor should be stopped to the stop of the rotation of the servo motor. Since there is no "deceleration time"), the amount of movement of the servomotor from the occurrence of the situation where the rotation of the servomotor should be stopped until the rotation of the servomotor stops can be set without limiting (slowing) the rotation speed of the servomotor. , Can be further reduced.

In particular, in the field of semiconductor manufacturing equipment, due to the recent trend toward miniaturization, the amount of movement of the servomotor from the occurrence of a situation in which the rotation of the servomotor should be stopped until the rotation of the servomotor has been stopped is determined. There is an increasing demand for reducing the rotation speed of the motor without limiting (slowing) it. Therefore, when the robot to be controlled is a wafer transfer robot, the above-described effects can be significantly exerted.

The situation where the rotation of the servomotor should be stopped includes, for example, when the power of the servomotor is turned off and when the emergency stop switch is turned on. Further, when the power supply of the servomotor is turned off, for example, there is an interruption of the power supply of the servomotor due to an emergency stop of the host device, a power failure of the commercial power supply, an abnormal decrease in the voltage of the power supply of the servomotor, and the like.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. The robot control device according to the present embodiment controls a part of the wafer transfer robot as a control target. Therefore, first, the wafer transfer robot will be described with reference to FIG. As shown in FIG. 4, the wafer transfer robot 32 moves the open cassette 30 to each processing apparatus or from each processing apparatus to the open cassette 3.
In this case, the wafer 31 is automatically transferred to one or more wafers at a time.

The wafer transfer robot 32 includes a slide portion 34 for moving a hand holding the wafer 31 in a horizontal direction, a turn portion 35 for rotating the slide portion 34 on a horizontal plane, a slide portion 34 and a turn portion 35. And a lift unit 33 for moving the vertical direction.
The robot controller of the present embodiment controls the vertical movement of the lift unit 33 of the wafer transfer robot 32.

Next, the outline of the operation of the robot control device according to the present embodiment will be described. FIG. 1 is a block diagram of a control device for a robot according to the present embodiment. As shown in FIG. 1, the control device for a robot according to the present embodiment controls the position of a servomotor 15 by a servo mechanism. still,
As described above, the servo motor 15 is a drive source of the lift unit 33 of the wafer transfer robot 32 (see FIG. 4).

In the robot controller of the present embodiment, when a pulse signal (corresponding to a "target position command value") for commanding the rotation angle of the servomotor 15 is given from the pulse oscillator 11, this pulse The signals are integrated by the deviation counter 12, converted into a speed command voltage by the D / A converter 13, and applied to the drive circuit 14.
The servo motor 15 starts rotating.

At this time, when the supply of the pulse signal is stopped, a feedback pulse (corresponding to the "current position detection value") from the encoder 16 which is a "position sensor"
As a result, droop pulses (corresponding to "deviation") of the deviation counter 12 decrease, the speed command voltage from the D / A converter 13 also decreases, and the servo motor 15 decelerates. Thereafter, when the accumulated pulse of the deviation counter 12 becomes “0”, the servomotor 15 stops. While the servomotor 15 is stopped, the stop position is always corrected by a feedback pulse from the encoder 16 to generate an electric braking force (servo lock). Therefore,
In the robot controller of the present embodiment, the servomotor 15 can be stopped by rotating the servomotor 15 by a rotation angle proportional to the number of pulses of the given pulse signal.

Further, in the robot control apparatus according to the present embodiment, as shown in FIG.
The power supply monitoring relay 21 is connected to the R phase and the T phase of No. 5. Therefore, when the power supply 25 of the servo motor 15 is turned off, the power supply monitoring relay 21 is opened, so that the transistor 24
Supplies an electric signal (corresponding to a “stop command”) to the pulse oscillator 11, and an electric signal (corresponding to a “stop command”) to the deviation counter 12 from the transistor 22. Then, when an electric signal is provided from the transistor 22 to the deviation counter 12, the pulse oscillator 11 stops supplying a pulse signal for instructing the rotation angle of the servomotor 15. The deviation counter 12
Clears the pool pulse to "0".

Therefore, as shown in FIG. 2, when the power supply 25 of the servo motor 15 is turned off, the power supply monitoring relay 21 opens in a response time of about 20 ms or less, and The supply of the pulse signal for commanding the rotation angle of the servo motor 15 from the oscillator 11 is stopped, and at the same time, the accumulated pulse of the deviation counter 12 is set to “0”.
(See FIG. 1), the servo motor 15
, The rotation of the servo motor 15 is stopped, and the rotation speed of the servo motor 15 becomes “0”. After that, the holding brake (mechanical brake) is operated.

Here, the amount of movement of the servomotor 15 from the time the power supply 25 of the servomotor 15 is turned off to the time when its rotation stops ("the amount of motor movement" in FIG. 2) is the conventional one ("Motor movement" in FIG. 5). 5) and “motor deceleration time” in FIG. 5 in the related art, there is no “motor moving amount” in FIG.
Is significantly smaller than the “motor movement amount” in FIG. Therefore, the “time required for an instantaneous stop” from turning off the power supply 25 of the servomotor 15 to operating the holding brake (mechanical brake) is also significantly reduced.

In order to verify that the “motor movement amount” of FIG. 2 is significantly smaller than the “motor movement amount” of FIG. 5, the lift unit 33 of the wafer transfer robot 32 of FIG. The power supply 25 of the servomotor 15 was turned off while the robot was being lowered downward, and the falling distance of the lift portion 33 at that time was measured. Further, FIG.
, The measurement results obtained by the control device of the robot according to the present embodiment are plotted with “□”, and “□” is connected by a solid line. Also, in FIG. 3, the measurement results in the conventional technique are plotted with “、”, and “◆” is displayed by connecting with a dotted line.

According to FIG. 3, no matter what operating speed the lift unit 33 is lowered, the robot controller of the present embodiment makes the fall distance of the lift unit 33 about 10 times smaller than that of the prior art. It can be less than one part. The operating speed of the lift unit 33 is proportional to the rotation speed of the servo motor 15, and the falling distance of the lift unit 33 is determined by the amount of the servo motor 15 from when the power supply 25 of the servo motor 15 is turned off until its rotation stops. The moving distance (“Motor moving distance” in FIG. 2,
In consideration of the fact that it is proportional to the “motor movement amount” in FIG. 5, the “motor movement amount” in FIG. 2 is about 10 times smaller than the “motor movement amount” in FIG. It is considered to be less than one part.

In the robot controller of the present embodiment, the power supply monitoring relay 21 having a relay structure is used as a sensor for monitoring the power supply 25 of the servomotor 15. Any sensor can be used as long as it can monitor 25 (for example, a sensor using a Hall element).

As shown in FIG. 1, the robot controller of the present embodiment also has an emergency stop switch 23. When the emergency stop switch 23 is depressed, the transistor 24 switches from the transistor 24 to the pulse oscillator 11. An electric signal is supplied, and an electric signal is supplied from the transistor 22 to the deviation counter 12. Therefore, when the emergency stop switch 23 is pressed, the power supply 25 of the servo motor 15 is turned off (that is, the power supply monitoring relay 21 is opened).
The same control as described above is performed.

The power supply monitoring relay 21 and the emergency stop switch 23 are connected via an OR circuit 26 to the transistor 22,
24, the power supply 2 of the servo motor 15
5 is turned off or the emergency stop switch 23
When is pressed, the robot control device of the present embodiment performs the above-described control.

Therefore, in the robot controller of the present embodiment, the power supply monitoring relay 21 and the transistor 2
2, 24, emergency stop switch 23, OR circuits 26, 24
The “stop command generating means” is configured by an electric circuit including a V control DC power supply, GND, and the like.

As described above in detail, in the robot control apparatus according to the present embodiment, as shown in FIG. 1, the rotation of the servo motor 15 which is the drive source of the lift section 33 of the wafer transfer robot 32 shown in FIG. · Stop the pulse generator 11
And a feedback signal from the encoder 16 of the servo motor 15 (a droop pulse of the deviation counter 12).

Then, the wafer transfer robot 32 shown in FIG.
For example, when the power of the servo motor 15 is turned off or when the emergency stop switch 2
When the situation where the rotation of the servomotor 15 should be stopped occurs, for example, when the motor 3 is turned on, the power supply monitoring relay 21, the transistors 22, 24, the emergency stop switch 23, the OR circuit 26, a DC power supply for controlling the 24V, GND, etc. An electric signal is supplied to the pulse oscillator 11 and the deviation counter 12 by the electric circuit composed of the steps (a) and (b). The supply of the pulse signal for commanding the rotation angle of the servomotor 15 is stopped, and the accumulated pulse of the deviation counter 12 is cleared. Then, the rotation of the servo motor 15 is stopped.

The time when the power supply 25 of the servo motor 15 is turned off means, for example, that the wafer transfer robot 3 shown in FIG.
In the second case, there is an interruption of the power supply 25 of the servomotor 15 due to an emergency stop of the host device, a power failure of the commercial power supply, an abnormal decrease in the voltage of the power supply 25 of the servomotor 15, and the like.

That is, in the robot controller of the present embodiment, when a situation where the rotation of the servomotor 15 should be stopped occurs, the power supply monitoring relay 21 and the transistor 2 are turned off.
2, 24, emergency stop switch 23, OR circuits 26, 24
By operating an electric circuit composed of a DC power supply for control of V, GND and the like, the current position and the target position of the servo motor 15 are made to coincide with each other. Since the rotation is stopped, the rotation of the servo motor 15 can be stopped at the moment when the rotation of the servo motor 15 should be stopped, as shown in FIG. Therefore, the servo motor 15
Since the rotation speed of the servo motor 15 is not set to “0” by the dynamic brake between the occurrence of the situation where the rotation of the servo motor 15 should be stopped and the rotation of the servo motor 15 being stopped (see “Motor deceleration time” in FIG. 5). Does not exist), the servomotor 15 from when the rotation of the servomotor 15 should be stopped until the rotation of the servomotor 15 stops.
(The "motor movement amount" in FIG. 2) can be reduced to about one-tenth that of the prior art without limiting (slowing) the rotation speed of the servo motor 15 (see FIG. 3). .

In particular, in the field of semiconductor manufacturing equipment, there is a tendency for miniaturization in recent years, and the amount of movement of the servomotor 15 from when the rotation of the servomotor 15 should be stopped until the rotation of the servomotor 15 stops. To the servo motor 15
It has been required to further reduce the rotation speed without limiting (slowing) the rotation speed. Therefore, when the robot to be controlled is the wafer transfer robot 32 shown in FIG. 4 as in the present embodiment, the above-described effects can be significantly exerted.

Specifically, in the wafer transfer robot 32 shown in FIG. 4, since the servomotor 15 is used as a drive source of the lift unit 33 which operates in the vertical direction, the power supply 25 of the servomotor 15 is turned off. Slide part 3 at the time
4 and the wafer 3 held by the hand of the slide unit 34
This is effective in reducing the amount of fall such as 1.

It should be noted that the present invention is not limited to the above embodiment, and various changes can be made without departing from the gist of the present invention. For example, in the robot controller according to the present embodiment, the fact that the power supply 25 of the servomotor 15 is turned off indicates that the power supply monitoring relay 2 has a response time of about 20 ms or less.
1 was detected. Accordingly, if the power supply 25 of the servo motor 15 is detected to be turned off by a sensor having a faster response time (for example, a Hall element), the servo motor 1
5, the amount of movement of the servomotor 15 from the time the power supply 25 is turned off until its rotation stops (the "motor movement amount" in FIG. 2)
Consequently, the falling distance of the lift 33 of the wafer transfer robot 32 in FIG. 3 can be further reduced.

Further, the robot control apparatus according to the present embodiment controls the position of the servo motor 15 by a servo mechanism as shown in FIG. 1, but at the same time, controls the speed of the servo motor 15 by the servo mechanism. May be performed. Further, the control device of the robot according to the present embodiment has been described with the digital servo system configuration, but the robot control device of the present embodiment may have an analog servo system configuration.

[0039]

According to the robot controller of the present invention, the stop command generating means is operated when the situation in which the rotation of the servomotor should be stopped occurs, so that the current position of the servomotor matches the target position. Since the rotation of the servomotor is stopped during the position control of the servo mechanism, the rotation of the servomotor can be stopped at the moment when the rotation of the servomotor needs to be stopped. Therefore, the rotation speed of the servo motor is not set to “0” by the dynamic brake during the period from the occurrence of the situation where the rotation of the servo motor should be stopped to the stop of the rotation of the servo motor. Since there is no "deceleration time"), the amount of movement of the servomotor from the occurrence of the situation where the rotation of the servomotor should be stopped until the rotation of the servomotor stops can be set without limiting (slowing) the rotation speed of the servomotor. , Can be further reduced.

In particular, in the field of semiconductor manufacturing equipment, due to the recent trend toward miniaturization, the amount of movement of the servomotor from the occurrence of a situation where the rotation of the servomotor should be stopped until the rotation of the servomotor has been stopped is determined. There is an increasing demand for reducing the rotation speed of the motor without limiting (slowing) it. Therefore, when the robot to be controlled is a wafer transfer robot, the above-described effects can be significantly exerted.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control device for a robot according to the present invention.

FIG. 2 is a timing chart when the operation of the wafer transfer robot is instantaneously stopped when the power supply of the servomotor is turned off in the present invention.

FIG. 3 is a diagram comparing the fall distance of the hand of the wafer transfer robot when the operation of the wafer transfer robot is instantaneously stopped when the power supply of the servo motor is turned off, between the present invention and the prior art. .

FIG. 4 is a perspective view of a wafer transfer robot to be controlled by the robot control device of the present invention.

FIG. 5 is a timing chart in the prior art when the operation of the wafer transfer robot is instantaneously stopped when the power supply of the servomotor is turned off.

[Description of Signs] 11 Pulse oscillator 12 Deviation counter 15 Servo motor 16 Encoder 21 Power monitoring relay 23 Emergency stop switch 32 Wafer transfer robot

Claims (4)

[Claims] 1. A robot controller for performing rotation / stop of a servomotor which is a drive source of a robot based on a deviation between a target position command value and a current position detection value fed back from a position sensor of the servomotor. A stop command generating means for giving a stop command, when the stop command is given from the stop command generating means, the supply of the target position command value is stopped,
A controller for stopping the rotation of the servomotor by clearing the deviation. 2. The robot control device according to claim 1, wherein the stop command generation means monitors a power supply of the servomotor, and issues the stop command when the power supply is turned off. A control device for a robot. 3. The control device for a robot according to claim 1, wherein the stop command generating means includes an emergency stop switch, and when the emergency stop switch is turned on,
Giving the stop command. 4. The robot control device according to claim 1, wherein said robot is a wafer transfer robot.