JPS5877489A - Preventive device for uncontrolled movement of industrial robot - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention relates to an industrial robot, and particularly to a robot that performs feedback control via digital calculation processing.
The present invention relates to a device that prevents the movable part from running out of control.

Since industrial robots are automated devices, mechanical or electrical failures may cause their arms (moving parts) to run out of control, damaging the robot itself or surrounding equipment, or even causing harm to humans.

In particular, in the case of a teaching/reproduction type robot, when teaching, a person holds the arm and works very close to the robot4, or even when using a teaching panel, the person works at a close distance of the arm while checking the teaching trajectory. However, these tasks are always dangerous.

FIG. 1 is a block diagram of the electrical system of a robot that performs feedback position control through digital calculation processing. 1
is a CPU as a control calculation means.

2 is a soft gain multiplier that applies an operational multiplier to the control value data from the CPU 1; 3 is a D/A converter that converts the digital data from the soft gain multiplier into analog data; 4 is a servo amplifier; and 5 is a hydraulic servo. An actuator such as a motor or a DC servo motor is used as a drive source to operate an arm (movable part). Reference numeral 6 denotes a position detector as an internal world measurement function, and this position information is fed back to the CPU 1.

There are various causes of runaway in such a feedback position control system. If the position detector 6 is out of order,
The CPU 1 can detect if the detector data does not change or there are large jumps in the data despite issuing an operation command to the actuator 5. On the other hand, cpul
A failure between the actuator 5 and the actuator 5 can only be detected by the CPU 1 through individual detectors, and even if it is detected, it is often after the actuator 5 has operated considerably.

From experience through development and trial production to date, it has been found that the D/A converter 3 is the most easily damaged among the semiconductor components constituting the control system.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a device that detects a failure of a D/A converter and prevents a robot movable part from running out of control.

To summarize the present invention, there is provided a circuit means for detecting that the output of a D/A converter that converts a digital signal into an analog signal whose output source is a control/arithmetic means has deviated from a predetermined voltage level range, and this circuit means. This is a runaway prevention device characterized by comprising a switching means for almost instantaneously deactivating a servo amplifier system based on the output of the servo amplifier system.

This invention will be explained below with reference to Examples.

FIG. 2 is a block diagram of one embodiment. cpul.

Soft gain multiplier 2. D/A converter 3. The actuator 5 and the position detector 6 are the same type as shown in FIG.
Contains servo power supply connected to mains power supply. A switching circuit 7 provides a signal for activating or deactivating the servo amplifier system 4. 8 is D/A' converter 3
This is a detection circuit that constantly monitors the analog output υ of
While giving the output signal to the switching circuit 7, cp
It is configured so that it is also given to ul.

D/A converter 3 at full range 10A volts or θ
Failures when used at ~+A volts are rare when outputting random voltages within this range, and are at ground level (
GND) or exceeds the output range and gets stuck near the converter's power supply voltage.

If a voltage close to the power supply voltage is output without a safety device, the actuator 5 will rapidly drive the robot arm as a movable part to the maximum, which is extremely dangerous.

The detection circuit 8 detects the magnitude of the absolute value of the output voltage p of the D/A converter 3 (uAl+α volts) (where A is the range setting value and α (α>0) is the allowable range, which is approximately 10 to 20 of IAI. %), an abnormal signal is output. This abnormal signal is immediately transmitted to the switching circuit 7.
is activated, a control signal is given to the servo amplifier system 4', and the main power supply (three-phase), which is the supply source of the servo power, is cut off. The servo amplifier is deenergized and stops the actuator 5 almost instantaneously. At the same time, the movement of the arm also stops. On the other hand, the abnormality signal from the detection circuit 8 is also input to the CPU 1 and used for control operations. Preferably, based on this abnormality signal, a separately provided display circuit may notify which axis of the robot the D/A converter corresponds to is abnormal. Since robots generally have multiple axes, this has the advantage of being able to quickly detect failures.

This is shown in more detail in FIGS. 3 and 4. The robot body is 5
Assume an articulated robot with axes. DC servo motors 51, 52 as actuators corresponding to each axis.・
......55 are provided. Similarly, a servo amplifier system and a D/A converter are also provided corresponding to each axis, and each servo power supply 41, 42 . ...
..., 45 are connected to the main power supply 100 in parallel. Of course, the detection circuit is connected to each D/A converter 31, 32.
．． . . . , 35, and are provided with reference numerals 81, 82, respectively. .......

85. Detection circuits 81, 82 including comparison circuits (comparators). . . . , 85 outputs are connected to relays 71, 72 . . . , respectively. . . . 75 and are connected in series, and also connected to the relay power source (2) via the relay 76. The normally open contact 76 of this relay 76 constitutes a switch for supplying or cutting off three-phase AC power to the main power supply 100. 110 is CPU
1, and the detection circuits 81, 82 . ......, when an abnormal signal is input from any of 85, which axes s1, s2, .
..., 85 D/A converters 31, 32 .・・・
. . , 35 is malfunctioning or not is indicated by, for example, an LED.

The detection circuit 8 basically has two
one comparator 87, 88;
88, and an OR circuit 89 which receives the respective outputs of 88 as inputs. The output voltage t of the D/A converter 3 is applied to the non-inverting input of the comparator 87 and the inverting input of the comparator 88, while the comparison voltage of 11.5 V is applied to the inverting input of the comparator 87, and the non-inverting input of the comparator 88 -11.5V is given as a comparison voltage.

This assumption is that the operating range of the D/A converter 3 is -10 (V)≦7≦+10 (V), and the power supply voltage is ±15 (V).

Regarding the operation, the D/A converter 31 corresponding to the Sl axis
A case in which the output voltage is about to exceed +11.5V due to a failure will be explained. As shown in FIG. 4, in the detection circuit 81, the output of the comparator 87 is inverted from low level to high level, and a high level signal is derived from the OR circuit 89. This high level signal energizes relay 71 and its contact 7
Open 1. Relay 76 is deenergized and its contacts 76' are opened to cut off the supply of alternating current power (AC) to main power supply 100. Servo power supplies 41, 42.・・・・・・
.

45 immediately starts the servo motors 51, 52 .・・・・・・
.

Stop power supply to 55. The arms for five axes (not shown) immediately stop. On the other hand, an abnormality signal from the detection circuit 81 is input to the CPU, and this abnormal signal is transmitted from the CPU to the abnormality display circuit 110 to light up the LED corresponding to the 51 axis. This determines which axis D/
It is easy to know whether the A converter has failed.

Note that the CPU 1 is programmed in advance to stop internal control/arithmetic processing in response to this abnormality signal, and to perform control in an abnormality mode.

If a failure occurs, the above operation will be performed on the other axis S2. S3゜s4
, s5.

As is clear from the above explanation, the present invention provides levers, D
Since the servo amplifier system is almost instantaneously deactivated by detecting that the output of the A/A converter deviates from a predetermined voltage level range, at least the robot's moving parts based on the D/A converter can be prevented from running out of control. It has the effect of preventing this from happening.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the electrical system of the robot, Fig. 2 is a block diagram of an embodiment of the present invention, Fig. 3 is a block diagram showing more specifically what is shown in Fig. 2, and Fig. 4. FIG. 1 is a circuit diagram showing an example of a detection circuit according to the present invention. 1. CPU, 3. D/A converter, 1-, + = Boamp system, 5... Actuator, 6... Position detector, 7... Switching circuit, 8... Abnormality detection circuit.

Claims (2)

[Claims] (1) An electrical circuit for an industrial robot in which feedback position control is performed through digital calculation processing, which is the output of a D/A converter that converts a digital signal using the control/calculation means as an output source into an analog signal. A runaway industrial robot characterized by comprising circuit means for detecting that the voltage has deviated from a predetermined voltage level range, and switching means for instantaneously deactivating a servo amplifier system based on the output of the circuit means. Prevention device. (2) The control/calculation means is configured to control the control/calculation means from the circuit means to the D
Claim (1) further includes a function of outputting a display signal to display means for indicating a failure state provided corresponding to each axis of the robot when a signal indicating that the /A converter has failed is received. The described industrial robot runaway prevention device.