Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Patent
1989-03-22
1991-01-29
Ip, Paul
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
31856818, 318616, 318618, 318636, 364513, G05B 1942
Patent
active
049889346
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to a robot control apparatus which performs teaching/playback-type position control with regard to a robot having a plurality of drive axes.
2. Background Art
The basic operation in ordinary teaching/playbacktype robot control comprises a teaching operation, in which the robot is first moved manually, by using a teaching pendant, to store motion point position information and tasks to be performed at these points in the data memory of a controller, an editing operation, in which the taught subjected matter stored in the data memory, namely the robot command data, is altering using an MDI & CRT unit, etc., of the controller, and a playback operation and automatic running performed after the teaching and editing operations.
In the playback operation and automatic running phase, a predetermined velocity command is applied to a drive mechanism of each controlled axis of the robot hand, thereby controlling the drive of these mechanisms simultaneously so that a predetermined task can be accomplished. With regard to the traveling velocity of the robot arm at such time, motion velocity can be decided as a ratio with respect to the maximum velocity, which is set for the robot arm, by an override function at the time of manual feed and by a motion velocity modification command and a set value of override at the time of playback operation. The reason for this is that it is required that the traveling velocity of the hand be suitably altered, in dependence upon the task performed by the robot, at automatic running and playback.
When teach data for each drive axis is decided in dependence upon the attitude of the robot arm with regard to taught starting and end points in the foregoing conventional robot control apparatus, there are occasions where, depending upon the motion, the load acting upon a motor during the motion exceeds the maximum output of a motor. Consequently, at the time of the teaching operation, it is required that a motion velocity modification command be set in such a manner that the load which will act upon the motor during the motion will fall within an allowable value range to lower the motion velocity. This places an excessive burden upon the operator as far as performing the teaching operation is concerned.
Conversely, depending upon the motion to be taught, there are times when the load acting upon the motor falls below the maximum output of the motor even though the robot arm moves at the set maximum velocity. The reason for this is that in a conventional robot control apparatus, the maximum velocity of motion and the acceleration/deceleration time constant along each drive axis are fixed at constant values at all times regardless of the type of robot motion performed.
More specifically, if a robot arm is capable of being driven at a higher velocity and, moreover, with a shorter time constant, whenever necessary, the maximum velocity and time constant cannot be changed even though motion at the higher speed becomes possible. Consequently, the improvement in robot efficiency is not satisfactory.
DISCLOSURE OF THE INVENTION
The present invention has been devised in order to solve the foregoing problems and its object is to provide a robot control apparatus in which the maximum velocity and time constant of each axial motor are decided for each and every taught motion to simplify the teaching operation and raise the motion speeds.
In accordance with the present invention, there can be provided a robot control apparatus for controlling a plurality of drive axes simultaneously by outputting a drive command to a motor having an acceleration/deceleration function, comprising memory means for storing teach data which stipulates a type of motion of a robot arm from a starting point to an end point, arithmetic means for deciding maximum velocity and an acceleration/deceleration time constant along each drive axis in such a manner that a load which will act upon each axial motor will attain a maximum output of the respective motor during motion bet
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Kikuchi Jun
Nihei Ryo
Torii Nobutoshi
Toyoda Kenichi
Fanuc Ltd.
Ip Paul
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