Proposal of nonlinear friction compensation approach for a ball-screw-driven stage in zero-speed region including non-velocity-reversal motion

This paper presents a heuristic friction compensation approach for handling the springlike friction behaviors of a ball-screw-driven stage in zero-speed region. The friction compensation for the motion that the stage is decelerated to stop and then accelerated in the same direction, which is also referred to as non-velocity-reversal motion, is discussed in detail. As the elastic energy stored in mechanical components may not be completely released during non-velocity-reversal motion, the conventional compensation approaches may not work well. Therefore, some other sophisticated friction compensation approaches become necessary for this kind of motion. In this study, a velocity pattern recognition algorithm is presented as the first step to classify the velocity patterns in zero-speed crossing region. Then, sinc function is exploited to model the nonlinear springlike friction of the ball-screw-driven stage. It is proved that the friction can be properly compensated for both the reversal motion and non-reversal motion. Experiments are performed to verify the proposed approach and it is demonstrated that the control performance is significantly improved.