Accurate Friction Compensation for a High Precision Stage using a Synchronous Piezoelectric Device Driver

It is well-known that one of the major limitations to achieve a good performance in mechanical systems is the presence of friction. High resolution positioning systems operating with accuracies in nanometer region usually exhibit relatively large steady-state tracking errors or even oscillations if controllers are designed without considering friction. Consequently, this paper aims at improving the position control of a high precision stage using a synchronous piezoelectric device driver (SPIDER) by comparing the performances of three friction compensators. These friction compensators detect friction in the system and use this information to modify the control input. The first using bang-bang control is based on the well-known static friction model. The second is a friction state observer based on the dynamic friction LuGre model, and the third is a feed-forward compensator based on the LuGre model. In order to effect a fair comparison, three friction compensators uses the same identified friction parameters in controller synthesis. The performance comparisons are presented by means of experimental results on the proposed high precision stage using SPIDER.