JPH05345293A - Collision prevention of industrial robot - Google Patents

Abstract

PURPOSE:To prevent collision with a foreign object by way of smoothly stopping a robot by detecting the foreign object in front of the movable part of the robot in the moving direction, finding distance between the robot and the foreign object, moving and stopping the robot while decelerating the robot between the robot and the foreign object at constant adjustable speed. CONSTITUTION:By a proximity sensor 3 provided in front of the movable part of a robot in the moving direction, distance between the movable part of the robot 2 and a foreign object, and from the distance and by an adjustable speed computing element 41, adjustable speed to stop the movable part of the robot 2 is computed, and the movable part of the robot 2 is decelerated at the constant adjustable speed and stopped. Consequently, as the movable part of the robot 2 is decelerated in accordance with the distance between the foreign object and the movable part of the robot 2 at the time when the foreign object is detected and stopped immediately before the foreign object, no impulsive inertial force works upon the robot 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing an industrial robot from colliding with a foreign body during operation.

[0002]

2. Description of the Related Art Conventionally, a robot is prevented from being damaged by colliding with a foreign object or colliding with an operator when the robot is traveling or turning the arm of the robot. Therefore, the following method is adopted. That is, as a first embodiment, a proximity sensor whose electrostatic capacitance output changes when an object approaches is attached to the movable part of the robot, and while the robot is operated in a predetermined sequence, the output of the proximity sensor at that time is displayed. , Compare the output of the proximity sensor when the foreign body is checked in advance, that is, when the foreign body is operated in a predetermined sequence with no interference between the foreign body and each part of the robot, and a certain output difference or more is generated. When a foreign body is approached when it hits, the operation of the robot is immediately stopped is disclosed (for example, Japanese Patent Laid-Open No. 59-59).
-81090). In addition, on the front surface of the moving part of the robot in the moving direction, pulse ultrasonic waves are emitted in the moving direction,
Detects the echo reflected on the object and measures the distance between the object and the sensor based on the time difference between the time when the object is emitted and the time when the echo is detected.A non-contact type distance measuring sensor that points in the direction of movement and is set from the current position of the robot Compare the distance to the moving position and the distance to the object detected by the distance measuring sensor at the current position, and when the distance to the object is shorter than the distance to the set moving position, the foreign object A method of determining that a robot has entered and stopping the operation of the robot is disclosed (for example, Japanese Patent Laid-Open No. 58-82696).
issue).

[0003]

However, in any of the above methods, in order to immediately stop the operation of the robot when it is determined that a foreign object has approached, a sudden stop occurs in the middle of the speed at which the robot operates according to the sequence. It will be. Therefore, a large impact due to inertial force may be applied to a tool or a driving device mounted on the robot body or arm, or a work held by a holding claw provided at the tip of the arm, and the work may be damaged at times. was there. The present invention smoothly stops the robot when a foreign object is detected,
The purpose is to prevent a collision with a foreign body.

[0004]

According to the present invention, a proximity sensor for detecting a foreign object is provided on a front surface of a movable portion of a robot in a moving direction, and an operation of the robot is stopped according to an output of the proximity sensor. In a robot collision prevention method, a detection distance between the proximity sensor and the foreign object is obtained, and a required stop distance is obtained by subtracting a minimum approach distance at which a movable part of the robot can approach the foreign object from the detection distance. A method of obtaining an acceleration / deceleration for decelerating and stopping at a constant acceleration during the required stop distance, and moving and stopping the movable part of the robot according to the acceleration / deceleration.

[0005]

The distance between the moving part of the robot and the foreign object is measured by the proximity sensor provided on the front side in the moving direction of the moving part of the robot, and the moving part of the robot is stopped by the acceleration / deceleration calculator from the distance. The acceleration / deceleration up to is determined, and the movable part of the robot is decelerated and stopped at the constant acceleration / deceleration. Therefore, the movable part of the robot is decelerated according to the distance between the foreign body and the movable part of the robot when the foreign body is detected, and the robot stops immediately before the foreign body, so that the inertial force that impacts the robot does not occur. Does not work.

[0006]

Embodiments of the present invention will be described with reference to the drawings.
1 is a side view showing an embodiment of the present invention, in which a robot 2 travels on a rail 1, a swivel portion 22 is provided above a base 21 of the robot 2, and a swivel portion 22 is provided above the swivel portion 22. The first arm 23 is provided so as to be tiltable, the second arm 24 is provided at the tip of the first arm 23 so that it can be tilted, and the wrist portion 25 can be tilted at the tip of the second arm. It is provided in. The front surface of the base 21 in the traveling direction, the front end portion and the rear end portion of the second arm 24, the second arm 2
A non-contact type proximity sensor 3 is provided on each side surface of the tip 4 near the tip. The proximity sensor 3 may be either one that uses the change in capacitance described in the conventional example or one that uses the echo of an ultrasonic wave. In addition, a sensor that uses the echo of a laser beam or an infrared ray, or a magnetic change It is sufficient to select a device whose detection value is not affected by the installation environment of the robot, such as a device using. Running the robot 2,
According to the acceleration / deceleration calculator 41 and the acceleration / deceleration calculated by the acceleration / deceleration calculator 41, the control device 4 for controlling each operation of the swing of the swivel unit 22 and the tilting movement of the first arm 23 and the second arm 24, Speed command device 4 for instructing each drive device 43 to decelerate the portion where each proximity sensor 3 is fixed
Two are provided. The acceleration / deceleration calculator 41 receives the output signal of the detection distance L measured by each proximity sensor 3, and the movable part of the robot can approach the foreign object from the detection distance L, as shown by the one-dot chain line in FIG. The required stop distance (L-δ) is obtained by subtracting the minimum approach distance δ, and the acceleration / deceleration α for decelerating and stopping at the constant stop distance (L-δ) is obtained. Incidentally, the acceleration alpha, if the moving speed of the movable portion of the robot when detecting the different objects to is V, obtained by ^{α = V 2/2 (L} -δ). Here, a case will be described in which the work 6 gripped by the arm 5 of another robot enters the operating range in which the robot 2 is moving at the speed V due to occurrence of some abnormal state. Proximity sensor 3 provided on the front surface in the moving direction of the base 21
By inputting the output obtained by measuring the distance L between the robot and the work 6 to the acceleration / deceleration calculator 41, the acceleration / deceleration α until the stop is obtained, and the value is input to the speed commander 42, and the driving device 43 is used. The robot 2 is moved at a constant acceleration / deceleration α while decelerating and stopped. Therefore, the moving part of the robot is decelerated according to the distance between the foreign body and the robot when the foreign body is detected, and stops immediately before the foreign body, so that no shocking inertial force acts on the robot. The proximity sensor 3 provided at the tip of the second arm 24 of the robot 2 or the like.
Similarly, when the foreign body is detected by the foreign body, each drive device 43 of the revolving unit 22, the first arm 23, and the second arm 24 is similarly detected.
To the acceleration / deceleration in the movement direction obtained from the distance between the foreign body and the proximity sensor to move the tip of the second arm 24 or the like and stop the movement of the robot. Can be prevented. In addition, the proximity sensor 3 repeats the detection operation at fixed time intervals, and when the foreign body passes by before the moving part of the robot 2 stops and the proximity sensor 3 no longer detects the foreign body, the acceleration / deceleration command is stopped. However, the operation of the movable part may be continued by returning to the initial speed. In that case, it is not necessary to restart the movable part of the robot, and the work time is not wasted.

[0007]

As described above, according to the present invention, a foreign object is detected on the front surface of the movable portion of the robot in the moving direction,
Since the distance between the robot and the foreign body is calculated and the distance between the robot and the foreign body is decelerated by decelerating with a constant acceleration / deceleration and stopped, a shocking inertial force acts on the robot. Therefore, there is an effect that it is possible to prevent a collision with a foreign object without causing damage to the work or the mounted object by smoothly stopping.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention.

FIG. 2 is a block diagram of a control device of the present invention.

[Explanation of symbols]

 1 Rail 2 Robot 3 Proximity Sensor 4 Control Device 41 Acceleration / Deceleration Calculator 42 Speed Commander 43 Drive Device

Claims (1)

[Claims] 1. A front surface in a moving direction of a movable part of a robot,
Providing a proximity sensor for detecting a foreign body, in an industrial robot collision prevention method for stopping the operation of a robot according to the output of the proximity sensor, the detection distance between the proximity sensor and the foreign body is obtained, The required stop distance is obtained by subtracting the minimum approach distance at which the moving part of the robot can approach the foreign body from the detected distance, and the acceleration / deceleration for decelerating to a stop during the required stop distance with a constant acceleration is obtained. A method for preventing collision of an industrial robot, comprising moving and stopping a movable part of the robot according to a speed.