Gain scheduling-based friction compensation

In this paper, it is experimentally proved that friction can be regarded as damping in the case of low speed motion. According to that, friction can be seen like part of the process and not like disturbances. Utilizing the root-locus method for the purpose of analysis, it is established that the friction effect (stick-slip, hunting) can be rejected at low speed by means of large speed controller integral gain, with the stabilizing damping effect of the friction. The integral gain of the speed controller is realized by gain-scheduling utilizing the look-up table for the whole speed range. Remarkably good servosystem behavior is experimentally verified on a laboratory model by utilization of the proposed control concept.