JPS60104689A - Joint type 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 (a) Technical Field of the Invention The present invention relates to a robot that grasps an object and causes the object to perform a desired motion, and particularly relates to an articulated robot having a plurality of arms connected by joints.

(b) Background of the Technology Robots are often used in, for example, assembly factories, where they grip a desired part, make it perform a predetermined movement, and then attach it to another predetermined part.

Many of the robots used for such applications are called articulated robots, and as shown in Fig. 1, they have multiple joints 1 (generally represented by flexion joints indicated by circles and marks). There are two types of revolute joints: an arm 2 connected in series by a rotary joint, a hand 3 provided at the tip of the arm 2, and one arm constituting the joint 1, as shown in the cross-sectional view in Figure 2. It is built in the end of 2a and the axis A
It includes a servo motor 4 having A as its rotation axis, and an angle detector 5 provided at one shaft end of the servo motor 4.

The angle between one arm 2a and the other arm 2b is controlled by a feedback method using a drive signal given to each servomorph 4 from a command section (not shown).

In other words, the rotation of the servo motor 4 is controlled by the reduction gearbox 6.
is converted into an angle between one arm 2a and the other arm 2b, and the detected value of the angle detector 5 is used as a feed pack signal. Such control is performed on the servo motor 4 provided at each joint 1, and as a result, the two hands 3 perform desired movements.

In general, position information is used as a drive signal in robots, but recently, when smoothness or accuracy is required when controlling the trajectory of one hand 3, especially in articulated robots, position information is used as a drive signal. Along with position information, speed information calculated from the current position from moment to moment has come to be used as a signal.

(c) Prior art and problems In the articulated robot using feedback control as described above, the feed bank signal, that is, the angle detector 5
Needless to say, if an error occurs in the detection signal due to noise or the like, an error will occur in the movement of the next hand 3.

On the other hand, in the articulated robot that moves to the target position using only the position information, no calculations are performed using the position information during the trajectory, so the error does not cause any particular problems.

However, in an articulated robot that uses speed information, which will be described later, especially when the number of arms 2, that is, the number of joints 1, is large, 1
Errors in reading position information cause large errors in the calculated movement of the hand 3, and damage to various parts or the surroundings has become a problem.

(d) Purpose of the Invention An object of the present invention is to prevent the adverse effects of errors in angle detectors in articulated robots.

(e) Structure of the invention, that is, the articulated robot according to the present invention includes a joint, a plurality of arms connected by the joint, a servo motor provided at the joint and driving one arm with respect to the other arm;
and an angle detector for detecting the angle between one arm and the other arm connected by the joint 7)
A diagnostic device is provided for diagnosing the presence or absence of an abnormality in the detected value of the angle detector based on the difference between at least two detected values obtained by the same angle detector.

(f) Examples of the invention Next, the gist of the present invention will be specifically explained using examples.

FIG. 3 shows a block diagram of an embodiment of the invention.

In the figure, the reference numerals common to those in FIGS. 1 and 2 refer to the same objects, and 7 is a command unit that generates commands to move the arm 2, and 8 is a servo amplifier (described later) based on commands generated by the command unit 7. 9 is a servo amplifier that amplifies the drive signal for the servo motor 4; 10 is a servo amplifier that amplifies the drive signal for the servo motor 4; 10 is a control unit that generates a drive signal for the servo motor 4; This is a diagnostic device that diagnoses whether there is an abnormality in the detector and generates an alarm signal when a foreign item is detected.

The control unit 8 controls the joint shape 1 as illustrated in FIG. 1, for example.
In the case of a robot, each servo motor 4 provided at six joints 1 generates a desired velocity vector for the hand 3, for example, every 200 m5 based on the command given from the command unit 7. A necessary drive signal is generated, and each servo motor 4 rotates at a speed corresponding to the drive signal.

As a result, the hand 2 performs the movement described above.

The angle detector 5 detects the rotation angle of the servo motor 4, and the detected value is given to the control unit 8 as a feed hack signal.

The value determined by the diagnostic Wri speed of the diagnostic device 10.

For example, every 50/I3, the difference d between the detected values of the angle detector 5 is compared in advance with a preset reference value e, and the difference d
When the value exceeds the reference value e, an alarm signal is generated.

For example, if the rotational speed of the servo motor 4 is 1200 revolutions per minute, and the amount of change in the detected value of the angle detector 5 per rotation of the servo motor is 2000, then the diagnostic device 10 changes the detected value of the angle detector 5 for 50 μs. The amount of change in the detection value of the angle detector 5 during the next two detections is (1200x2000x50) / (60xl, 00
0,000)=2, therefore, during 50 μs the angle detector 5
If the amount of change in the detected value is, for example, 5, this is considered to be an error caused by noise or the like, and measures are taken such as stopping the motion of the articulated robot by an alarm signal.

Note that the value of the reference value e is determined by the rotational speed of the servo motor, the diagnostic speed of the diagnostic device 10, etc., and is determined in advance by simulation or the like.

Values that do not affect the motion of the articulated robot are used.

The operation will be explained below using the flowchart shown in FIG.

First, the value n1 of the angle detector provided at a certain joint θi is read and then a predetermined period of time (50 μS) is elapsed.

Read the value n2 of the same angle detector. The difference (n2-nl) between the values of the angle detector at this time is calculated, and it is determined whether the difference is within the reference value.

If it is within the reference value, the value n2 of the angle detector read the second time is used to perform the D calculation for the subsequent movement of the articulated robot.

If the value is outside the reference value, an alarm signal is issued to notify the maintenance personnel of the occurrence of an abnormality, and an error signal is sent to the control unit to stop the operation of the articulated robot.

(g) Detailed Description of the Invention According to the present invention, when an error in the angle detector in an articulated robot is detected, the operation can be stopped by an alarm signal. Damage etc. can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a mock diagram of an articulated robot, FIG. 2 is a structural diagram of the main parts of the articulated robot, FIG. 3 is a block diagram of an embodiment of the present invention, and FIG. 4 is an operation flowchart. In the figure, 1 is a joint, 2 is an arm, 3 is a hand, 4 is a servo motor, 5 is an angle detector, and 10 is a diagnostic device.

Claims (1)

[Claims] a joint, a plurality of arms connected by the joint, a drive source provided at the joint for driving one arm with respect to the other arm, and a drive source between one arm and the other arm connected by the joint. An articulated robot equipped with an angle detector that detects an angle is provided with a diagnostic device that diagnoses whether there is an abnormality in the detected value of the angle detector based on the difference between at least two detected values obtained by the same angle detector. An articulated robot characterized by: