Sensorless Nonsmooth H∞-Tracking Synthesis of Servosystems with Backlash and Coulomb Friction∗

The nonsmooth phenomena such as backlash and Coulomb friction, often occurring in mechanical systems, typically produce undesired inaccuracies, oscillations and instability thereby degrading the system performance. In this paper, the H∞ synthesis is developed for a class of nonsmooth systems and it is then applied to an industrial emulator where the described phenomena are present, and an elastic band is included in the transmission motor-load, and only motor position measurements are feasible. The effectiveness of the proposed method is supported by experimental results.