Switched chattering control vs. backlash/friction phenomena in electrical servo-motors

A switched control algorithm is developed to globally stabilize an electrical servo-motor operating under uncertainty conditions in the presence of complex non-linear phenomena such as backlash, stick-slip motion, etc. The controller constructed is referred to as a chattering controller and it does not rely on the generation of sliding motions while providing robustness features similar to those possessed by their sliding mode counterparts. Particularly, the chattering controller ensures robustness against external disturbances with the a priori known norm bounds, thus rejecting the influence of undesired backlash/friction effects on the motor. Stability analysis, given within the Lyapunov functions framework extended to discontinuous dynamic systems, additionally reveals a finite time convergence of the system trajectories to the equilibrium point. Performance issues of the controller are illustrated in a simulation study.