US 5,710,498 A · Method and apparatus for friction compensation

Abstract

Compensation for friction affecting motion of moveable machine members is effected in servo control of the member actuators. An estimate of velocity is used in evaluation of a model of frictional force to produce compensation values. Alternative embodiments provide continuous models of estimated velocity and frictional forces and state models of estimated velocity and frictional forces. Compensation values determined according to either embodiment may be produced for application to servo control commands such as position or torque. The compensation accounts for step changes of friction upon reversal of direction of travel.

Claims17

Dependent claims

A method of servomechanism control comprising the steps of:

a) producing a position command which is representative of the desired position of a controlled element;
b) deriving a value of estimated velocity from the position command, wherein the estimated velocity represents actual velocity of the controlled element;
c) determining values for frictional force as a function of estimated velocity and direction;
d) producing a compensation value in response to the value of frictional force, the compensation value changing with time according to a predetermined algorithm;
and
e) compensating servomechanism command values in response to the compensation value, the compensated servomechanism command values including a component to oppose frictional forces affecting motion of the controlled element.

3 more elements

Dependencies are inferred from the claim text.

Method and apparatus for friction compensation

Life of this patent

Method and apparatus for friction compensation

Life of this patent

Abstract

Claims17