US 4,973,895 AGranted

Motor drive method for an industrial robot

AssigneeFanuc Corporation

InventorsNobutoshi Torii, Tyo Nihei, Jun Kikuchi

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Abstract

A motor drive method is provided which is capable of preventing suspension of operation of an industrial robot, and preventing deviation of the track of movement from a command track, attributable to an overload state of a motor. Output torque command values for motors for various axes of the robot are detected (S1). When any one of the detected values exceeds a predetermined value, which is determined in accordance with the maximum output torque of each corresponding one of the motors for the various axes, an amount of move command per unit time, for every one of the axes, is reduced. The amount of move command per unit time is reduced by using the torque command values thus increased, the product of an override value and a coefficient obtained in accordance with the differential of the torque command values (S3, S6 and S14), whereby the overload state of the motor is prevented.

Claims10

Dependent claims

A motor drive method for an industrial robot which includes at least one operating section, a plurality of motors for driving the at least one operating section with respect to a plurality of axes, and control means for delivering a move command to a corresponding one of the motors, said method comprising the steps of:

(a) detecting the outputting torques of a predetermined plurality of motor;
(b) comparing each of the output torques thus detected with a predetermined value, determined beforehand in accordance with the maximum output torque of each corresponding one of the predetermined plurality of motors;
(c) storing the output torque if the output torque is less than the predetermined value;
(d) increasing an index value if the number of axes has not been reached;
(e) comparing stored override values with each other when the index value and the number of axes are the same;
(f) storing the smallest override value comparison in an override register;
and
(g) outputting the stored override value as a speed command for individually decreasing an amount of the move command per unit time, for every one of the predetermined plurality of motors.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/360,940Filed 4 May 1989
Priority: JP 62-27345930 Oct 1987
Granted: 27 Nov 1990
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

G05B 19/416
Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to…
G05B 19/4062
Characterised by monitoring or safety: monitoring servoloop, e.g. overload of servomotor, loss of feedback or reference
G05B 2219/34188
Director, elements to supervisory: safety, stop, slowdown interpolator if speed, position, torque error too large
G05B 2219/37344
Measurements: torque, thrust, twist, machining force measurement