JPH0619002U - Robot arm controller - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a control device for a robot apparatus, which corrects the axis deviation of an arm quickly and accurately without involving work by manpower. [Structure] The control circuit takes in the count values P ₁ and P ₂ from the counter (S1). The count values P ₁ and P ₂ indicate the positions (angles) of the motor shaft and the arm shaft. The axis deviation amount ΔP is calculated using the equation (1). The absolute value of the axis deviation amount ΔP and the threshold value ΔP _SET are compared (S3). If the amount of axis deviation is less than or equal to the threshold value (S3: ≦), the count value P ₁ is corrected to obtain P ₁ ′ (= P1 + ΔP) (S4). This value P ₁ ′
Is used to control the position of the motor (S5). When the amount of axis deviation exceeds the threshold value (S3:>), abnormal processing such as alarm notification is performed (S6).

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a device for controlling a robot arm, and more particularly to a device for correcting an axis deviation of the arm.

[0002]

[Prior art]

 Generally, in a robot apparatus, when the arm receives an excessive force from the outside, such as when the arm interferes with a structure or the like, an axis deviation may occur in the driving force transmission system of the arm. In order to maintain the operational reliability of the robot device, it is necessary to correct this axis deviation. There are two conventional methods for correcting the axis deviation, for example:

1. By re-teaching the teaching point to the robot device, the stored teaching point is changed to the position corresponding to the current position (shifted position).

2. If the alignment point (fixed point) is set at a certain point within the operating range of the robot unit and an axis shift occurs, the manpower guides the arm to the alignment point, and the deviation of the number of encoder pulses at this time is calculated. Then, the amount of axis deviation is calculated and corrected.

[0005]

[Problems to be solved by the device]

 However, the conventional axis deviation correction described above has the following problems.

1. In the case of re-teaching, manpower for teaching work is required, and the operation rate of the robot apparatus is lowered because the operation of the robot device is interrupted during the teaching work. Particularly, when there are many teaching points, the labor and time required become enormous and the above-mentioned drawbacks become remarkable. In addition, there is a safety problem because the teaching work is performed by approaching the robot arm operation area.

2. When the arm is guided to a fixed point for alignment, an accessory such as a jig for alignment is required. In addition, since the arm must be accurately aligned with the fixed point by hand, careful work is required, increasing the burden on manpower, and further increasing the work time and hindering the line availability. There is also a problem that the positioning accuracy depends on the manpower proficiency.

In view of the above problems, an object of the present invention is to provide, in a robot control device, a device that quickly and accurately corrects an axis deviation of an arm without a work by manpower.

[0009]

[Means for Solving the Problems]

 The structure of this device is shown in FIG. A robot arm control device according to the present invention is a device for controlling an arm shaft 103 connected to a motor drive shaft 102 via a transmission mechanism 101, and includes the following elements.

(1) A pair of angular displacement detection means 104, 105 for detecting angular displacement of the motor drive shaft 102 and the arm shaft 103.

(2) A pair of angle calculating means 106, 107 for calculating the angle of each axis from the detection outputs of the pair of speed detecting means 104, 105.

(3) Axis deviation amount calculation means 108 for calculating the axis deviation amount from the angle of each axis and the rotation speed ratio of the transmission mechanism 101.

(4) An angle correction unit 109 that corrects the angle of the motor drive shaft 102 based on the amount of axis deviation.

(5) Motor control means 110 for controlling the rotation of the arm shaft 103 based on the corrected angle.

(6) Judging means 111 for judging whether or not the amount of axis deviation is within the allowable range.

(7) An output unit 112 that operates when the amount of axis deviation deviates from the allowable range and outputs an abnormal axis deviation occurrence notification.

[0017]

[Action]

 According to the present invention, in the device for controlling the arm shaft by detecting the angular displacement of the motor drive shaft to obtain the angle of the motor drive shaft and driving the motor based on this angle, the motor drive shaft and the arm are controlled. Control is performed in consideration of misalignment with the axis. That is, the angular displacement of the arm shaft is detected separately from the motor drive shaft, and the amount of shaft deviation is determined from the rotation speed ratio of each shaft. Then, for example, if the amount of axis deviation is within the allowable range, the detected angle of the motor drive shaft is corrected to control the rotation of the arm axis, and if the amount of axial deviation exceeds the allowable range, drive of the arm axis is stopped. At the same time, it performs abnormal processing such as output of notification of abnormal axis deviation.

[0018]

【Example】

An embodiment of this invention will be described below. FIG. 2 is a schematic view of a main part of a robot arm control device according to an embodiment of the present invention. In the figure, 201 is a motor, 202 is a motor shaft, 203 is a speed reducer, and 204 is an arm shaft. The motor shaft 202 and the arm shaft 204 are provided with, for example, incremental encoders 205 and 206. Further, waveform shaping circuits 207 and 208, rotation direction detection circuits 209 and 210, and up / down counters 211 and 212 are configured corresponding to the encoders 205 and 206. The control circuit 213 operates according to a predetermined program, takes in the count values P ₁ and P _{2 of} the counters 211 and 212, and outputs a motor drive signal. The motor driver circuit 214 drives the motor 201 based on the motor drive signal.

FIG. 3 shows an outline of a program incorporated in the control circuit 213. The operation of this device will be described with reference to this figure. The up / down counters 211 and 212 count up / down the detection pulses according to the rotation direction and indicate the position (angle) of the motor shaft 202 and the arm shaft 204. The count values P ₁ and P ₂ are held. The control circuit 213 takes in the count values P ₁ and P ₂ for each control cycle (S1), and calculates the axis deviation amount ΔP using the equation (1). However, N is the speed reduction ratio of the speed reducer 203.

[0020]

## EQU1 ## ΔP = P₁-P₂/ N (1) Then, the absolute value of the axis deviation amount ΔP and the threshold value ΔP_SETAre compared with each other to determine whether the axis deviation is within the allowable range (S3). If the amount of axis deviation is less than or equal to the threshold value (S3: ≤), the count value P₁Correct P₁′ (= P1 + ΔP) is calculated (S4), and this value P ₁ The position control of the motor is carried out by using '(S5). On the other hand, when the amount of axis deviation exceeds the threshold value (S3:>), an alarm is given and an abnormal process is performed such as stopping the robot device (S6).

In other words, when an axis deviation occurs in the arm, even if the axis deviation is not negligible in position control but is within a mechanically permissible range, position control that compensates for the axis deviation is performed. To continue the operation of the robot device. This allows the robot apparatus to continue operating with a predetermined operational reliability, for example, when the arm interferes with the structure and causes a slight misalignment. If the amount of axis deviation is unacceptable due to the mechanism, it is determined that maintenance of the speed reducer 203 and the like is necessary, and the device is stopped.

[0022]

[Effect of device]

 As described above, according to the present invention, the shaft misalignment between the motor drive shaft and the arm shaft is detected, and the motor control is performed by correcting the detected angle of the motor drive shaft according to the amount of the shaft misalignment. Even if there is a non-negligible misalignment, it is not necessary to re-instruct, and the operation of the robot can be maintained. Therefore, there is an advantage that manpower required for re-teaching can be saved and safety can be improved, and the operation rate of the robot device can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of this invention.

FIG. 2 is a block diagram showing an outline of main parts of a robot arm control device according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a main procedure of processing in a control circuit.

[Explanation of symbols]

 101 ... Transmission mechanism 102 ... Motor drive shaft 103 ... Arm shaft 104 ... Motor drive shaft angular displacement detection means 105 ... Arm shaft angular displacement detection means 106 ... Motor drive shaft angle calculation means 107 ... Arm shaft angle calculation means 108 Axis deviation calculation means 109 ... Angle correction means 110 ... Motor control means 111 ... Judgment means 112 ... Output means

Claims (2)

[Scope of utility model registration request] 1. A device for controlling an arm shaft connected to a motor drive shaft via a transmission mechanism, the device comprising: a pair of angular displacement detection means for detecting an angular displacement of the motor drive shaft and the arm shaft. A pair of angle calculation means for calculating the angle of each axis from the detection output of the pair of speed detection means, and an axis deviation amount calculation means for calculating the axis deviation amount from the angle of each axis and the rotation speed ratio of the transmission mechanism, A robot arm control device comprising: an angle correction unit that corrects the angle of the motor drive shaft based on the amount of axis deviation; and a motor control unit that controls the rotation of the arm shaft based on the corrected angle. . 2. The robot arm control device according to claim 1, wherein the determining means determines whether or not the axis deviation amount is within an allowable range, and operates when the axis deviation amount deviates from the allowable range. A robot arm control device comprising: an output unit that outputs a notice of occurrence of an abnormal axis deviation.