Enhanced backstepping sliding mode controller for motion tracking of a nonlinear 2-DOF piezo-actuated micromanipulation system

In this paper a robust backstepping sliding mode controller is developed for tracking control of 2-DOF piezo-actuated micromanipulation system. The control approach is established to obtain high precision tracking in the existence of hysteresis nonlinearity, model uncertainties and external disturbances which treated as a lumped uncertainty. The control scheme is developed based on backstepping technique and a sliding surface is introduced in the final stage of the algorithm. To attenuate the chattering problem caused by a discontinuous switching function, a simple fuzzy system is used. The asymptotical stability of the system can be guaranteed since the control law is derived based on Lyapunov theorem. The effectiveness and feasibility of the suggested approach are tested for tracking of a micrometer-level reference trajectories. From the results, it is shown that the developed control system not only achieves satisfactory control performance, but also eliminates the chattering phenomena in the control effort.