Position -d e pe n den t Friction C om pensa t i o n for Ba I I se rew Tables

This paper describes a compensation scheme jor positional-dependent friction in ballscrew-type tables. Based on the observations of the experimental data, the friction of the ball-screw table exhibits periodical behavior with varying amplitudes upon different velocities. The friction proJile function f, (X) can be determined by measuring the static friction in each position. The parameter of amplitude for scaling the friction profile is calculated in real time Jbr friction compensation. This formulation is then applied to the friction observer developed by Hassig and Friedland. The convergence of the modiJied friction compensator is proved and the simulcrtion results demonstrate the ability of the proposed method.