JPH07237174A - Control device for industrial robot - Google Patents

Abstract

PURPOSE:To improve safety by reliably detecting overspeed of an absolute value encoder joined to a motor of respective joints of an industrial robot without depending on reliability of software. CONSTITUTION:An absolute value encoder 2 outputs an encoder signal 2a obtained by adding speed data to absolute value data. An absolute value of speed is shown by a pulse width, and the pulse width becomes large as the speed becomes large. A servo amplifier 3 takes in only the absolute value data, and controls a motor 1. When a high level condition of the encoder signal 2a continues for constant time, an overspeed detecting circuit 4 outputs an overspeed signal 4a, and the servo amplifier 3 stops the motor 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling a motor of each joint of an industrial robot by using an absolute value encoder.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing a conventional controller for an industrial robot. In the figure, (1) is a motor provided in each joint, (2) is an absolute encoder that outputs absolute data corresponding to the rotation amount of the motor (1), and (3) is an absolute encoder (3). It is a servo amplifier that controls the motor (1) by inputting the absolute value data of.

A conventional industrial robot controller is constructed as described above, and the servo amplifier (3) is an absolute encoder.
The rotation speed is calculated from the difference between the absolute value data sent from (2), and this is compared with the speed command value to control the motor (1). When the rotation speed obtained from the absolute value data exceeds a certain value, it is detected as an overspeed and the motor (1) is stopped. These calculations are processed by computer software.

[0004]

In the conventional industrial robot controller as described above, since the absolute value data from the absolute value encoder is entirely processed by software, the overspeed is detected by the software. There is a problem that it depends on reliability.

The present invention has been made to solve the above problems, and an industrial robot capable of reliably detecting overspeed and improving safety without depending on the reliability of software. It is an object of the present invention to provide a control device of.

[0006]

A control device for an industrial robot according to a first aspect of the present invention is provided with a rotation speed detecting device for detecting the rotation speed of an encoder and a rotation speed control computer provided separately. An overspeed detection circuit that outputs an overspeed signal when the output of the detection device exceeds a predetermined value.

A second aspect of the invention is a rotation speed detecting device for detecting the rotation speed of an encoder, and speed data obtained by converting the detected rotation speed into a pulse width is added to absolute value data from the encoder and transmitted. The transmission device includes an overspeed detection circuit which is provided separately from the control computer and outputs an overspeed signal when the transmitted speed data exceeds a predetermined value.

A third aspect of the invention is based on the second aspect of the invention, wherein the overspeed detecting circuit is configured to output an overspeed signal when the pulse width forming the speed data continues for a certain period of time. .

A fourth aspect of the present invention is a rotation speed detection device for detecting the rotation speed of an encoder, and speed data obtained by converting the detected rotation speed into a pulse width is added to absolute value data from the encoder and transmitted. And a rotation detecting device that calculates a rotation speed from the transmitted absolute value data, compares the rotation speed with speed data, and outputs an abnormal signal when the difference between the two exceeds a specified value. .

A fifth aspect of the present invention is, in the first to third aspects, provided with a switching device for setting a predetermined value for outputting the overspeed signal to be smaller during teaching of the robot than during automatic operation. Is.

[0011]

In the first aspect of the present invention, when the rotation speed of the encoder is equal to or higher than a predetermined value, in the second aspect, when the speed data obtained by converting the rotation speed into the pulse width is equal to or higher than the predetermined value, the third In the invention, since the overspeed signal is output when the pulse width forming the speed data continues for a certain time, the overspeed can be detected by hardware.

Further, in the fourth invention, speed data obtained by converting the detected rotation speed of the encoder into a pulse width is added to the absolute value data and transmitted, and the rotation speed is calculated from this absolute value data. Is compared with the speed data, and an abnormality signal is output when the difference between the two is greater than or equal to a specified value, so that it is possible to check the abnormality of the encoder data.

Further, in the fifth aspect of the invention, the predetermined value for outputting the overspeed signal is set to be smaller than that during automatic operation during robot teaching, so that overspeed is detected even at low speed during teaching. It

[0014]

【Example】

Example 1. 1 to 4 are views showing an embodiment of the first to third inventions of the present invention, FIG. 1 is an overall configuration diagram, FIG. 2 is a block diagram of an absolute value encoder, and FIG. 3 is an absolute value encoder. A transmission waveform diagram and FIG. 4 are block diagrams of the overspeed detection circuit, and the same parts as those of the conventional device are indicated by the same reference numerals.

In FIG. 1, (4) is an absolute encoder (2)
Of the absolute value encoder (2), that is, the overspeed of the motor (1), and outputs the overspeed signal (4a) to the servo amplifier (3). Is.

2 to 4, (5) is an absolute value data detecting device for detecting the absolute value data of the absolute value encoder (2), and (6) is a rotation detecting the rotational speed of the absolute value encoder (2). The speed detection device (7) adds the speed data B obtained by converting the rotation speed detected by the rotation speed detection device (6) into a pulse width to the absolute value data A detected by the absolute value data detection device (5). The transmitting device for transmitting the encoder signal (2a), the shift register constituting the overspeed detecting circuit (4), and the clock signal (9).

Next, the operation of this embodiment will be described. An absolute value encoder (2) coupled to the motor (1) transmits an encoder signal (2a) having a waveform in which velocity data B is added to absolute value data A as shown in FIG. The encoder signal (2a) is received by the servo amplifier (3) and the overspeed detection circuit (4). In the encoder signal (2a), the absolute value of the rotation speed is indicated by the pulse width, and the higher the rotation speed, the larger the pulse width. The servo amplifier (3) takes in only the absolute value data A and controls the motor (1).

In the overspeed detection circuit (4), the clock signal (9)
The contents of the shift register (8) are shifted by, and when the high level state of the encoder signal (2a) continues for a certain time, the overspeed signal (4a) becomes high level and the overspeed is detected. The overspeed signal (4a) is sent to the servo amplifier (3), and the servo amplifier (3) stops the motor (1).
In this way, overspeed can be detected without the intervention of software, and the safety of the robot can be improved.

Example 2. FIG. 5 is a block diagram of an abnormality detecting means showing an embodiment of the fourth invention. 1 to 3 are also used in the second embodiment. In the figure,
(11) is a speed calculating means for calculating speed data C from absolute value data A, (12) is a comparing means for comparing speed data C and speed data B, and (12a) is an abnormal signal. Means (13) are configured.

The servo amplifier (3) sends the absolute value data A of the received encoder signal (2a) to the speed calculating means (11), and the speed calculating means (11) calculates the speed from the difference value of the absolute value data A. Then, the speed data C is output. The comparison means (12) compares the speed data C and the speed data B, and outputs an abnormal signal (12a) when the deviation amount exceeds a specified value, and the servo amplifier
(3) stops the motor (1). In this way, the abnormality of the encoder signal (2a) is detected, and the reliability of the encoder signal (2a) can be improved.

In the second embodiment, the encoder signal (2a)
Only the abnormality detecting means (13) is shown, but if this is provided in the servo amplifier (3) shown in FIG. 1 of the first embodiment, it becomes more desirable for improving safety. That is, it is possible to detect an abnormality of the encoder signal (2a) in addition to the overspeed detection without software.

Example 3. FIG. 6 is a circuit diagram of an overspeed detection circuit showing an embodiment of the fifth invention of the present invention. In addition,
1 to 3 are also used in the third embodiment. In the figure, (14)
Is a positive power supply, (15) is a changeover switch, (16) (17) is a resistor, (18)
(19) is an AND gate, and (20) is an OR gate, the output of which is the overspeed signal (4a).

When the changeover switch (15) is set to the contact A side, when the output (8a) of the shift register (8) becomes high level, the output of the AND gate (18) becomes high level,
The overspeed signal (4a) which is the output of the OR gate (20) becomes high level, and the overspeed is detected. When the changeover switch (15) is set to the contact B side, the output (8b) of the shift register (8)
Becomes high level, the output of the AND gate (19) becomes high level and the output of the OR gate (20) becomes high level, and the overspeed is detected.

At this time, the output (8b) of the shift register (8)
Compared with the output (8a), is high level even if the pulse width of the encoder signal (2a) is short, so that the overspeed can be detected even when the rotation speed of the encoder (2) is low. As a result, it is possible to easily switch the overspeed detection value during teaching or automatic operation, and it is possible to further improve the safety of the robot.

[0025]

As described above, in the first aspect of the present invention, when the rotational speed of the encoder is equal to or higher than the predetermined value, in the second aspect, the speed data obtained by converting the rotational speed into the pulse width is equal to or higher than the predetermined value. Then, in the third invention, when the pulse width constituting the speed data continues for a certain period of time, the overspeed signal is output, so that the overspeed can be detected by the hardware and the reliability of the software can be improved. There is an effect that the overspeed can be surely detected without depending on it and the safety of the robot can be improved.

According to the fourth aspect of the invention, speed data obtained by converting the detected rotation speed of the encoder into a pulse width is added to the absolute value data and transmitted, and the rotation speed is calculated from this absolute value data and this is calculated. Compared with the speed data, an abnormal signal is output when the difference between the two exceeds a specified value, so it is possible to check the encoder data for abnormalities.
There is an effect that the reliability of encoder data can be improved.

Further, in the fifth invention, the predetermined value for outputting the overspeed signal is set to be smaller than that during the automatic operation during the teaching of the robot, so that the overspeed is detected even at the low speed during the teaching, This has the effect of improving the safety of the robot.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a first embodiment of the present invention.

2 is a block diagram of the absolute encoder of FIG. 1. FIG.

FIG. 3 is a transmission waveform diagram of the absolute encoder of FIG.

FIG. 4 is a block diagram of the overspeed detection circuit of FIG.

FIG. 5 is a block diagram of an abnormality detecting means showing a second embodiment of the present invention.

FIG. 6 is a circuit diagram of an overspeed detection circuit showing a third embodiment of the present invention.

FIG. 7 is a configuration diagram showing a conventional controller for an industrial robot.

[Explanation of symbols]

 1 Motor 2 Absolute Encoder 2a Encoder Signal 3 Servo Amplifier 4 Overspeed Detection Circuit 4a Overspeed Signal 5 Absolute Value Data Detection Device 6 Rotational Speed Detection Device 7 Transmitter 12a Abnormal Signal 13 Abnormality Detection Means 15 Switching Device (Changeover Switch)

Claims (5)

[Claims] 1. A motor having a motor provided at each joint of a robot, and an encoder driven by this motor to output absolute value data corresponding to a rotation amount. The output of this encoder is processed by a computer to produce the motor. In a device for controlling the rotation speed detecting device for detecting the rotation speed of the encoder, and an overspeed detecting circuit which is provided separately from the computer and outputs an overspeed signal when the output of the rotation speed detecting device exceeds a predetermined value. A control device for an industrial robot, comprising: 2. A motor provided at each joint of a robot, and an encoder which is driven by the motor and outputs absolute value data corresponding to a rotation amount. The output of the encoder is processed by a computer to produce the motor. In the device for controlling, a rotation speed detection device for detecting the rotation speed of the encoder, a transmission device for transmitting a signal obtained by adding speed data obtained by converting the detected rotation speed into a pulse width to the absolute value data, A control device for an industrial robot, comprising an overspeed detection circuit which is provided separately from the computer and outputs an overspeed signal when the transmitted speed data exceeds a predetermined value. 3. The control device for an industrial robot according to claim 2, wherein the overspeed detection circuit is configured to output an overspeed signal when the pulse width forming the speed data continues for a certain period of time. 4. A motor provided at each joint of a robot, and an encoder driven by this motor to output absolute value data corresponding to a rotation amount. The output of this encoder is processed by a computer to produce the motor. In the device for controlling, a rotation speed detection device that detects the rotation speed of the encoder, and a transmission device that transmits a signal in which speed data obtained by converting the detected rotation speed into a pulse width is added to the absolute value data, An industry characterized by comprising an abnormality detection means for calculating a rotation speed from the transmitted absolute value data, comparing the rotation speed with the speed data, and outputting an abnormality signal when the difference between the two exceeds a specified value. Robot control device. 5. A switching device for setting a predetermined value for outputting an overspeed signal to be smaller during teaching of the robot than during automatic operation. The control device for the industrial robot according to 1.