An anti-windup and backlash compensation-based finite-time control method for performance enhancement of a class of nonlinear systems

Real-world nonlinear control systems (e.g., robots) are influenced dynamically by backlash and saturation. However, it is lacking of a control design tool with a sound theory to deal with these phenomena and achieve optimal finite-time stability simultaneously. To this end, we propose a novel anti-windup and backlash compensation-based finite-time control (AWBC-FTC) method for an unsolved control task of a general class of unstable nonlinear systems under input saturation and backlash nonlinearity. It includes a compound control structure with two layers where the upper switches two control modes and the lower regulates the system in either the backlash mode or the contact mode. New stability theory together with parameter optimization algorithms are also proposed to support new design approaches of two sub-controllers where the adversary effects of input saturation and backlash are eliminated and the optimal finite state stability under a guaranteed domain of attraction is achieved. Experimental results on a benchmark robot system verify the advantages of the proposed design tools over the other in terms of a bunch of transient and stability measures. Therefore, the work enriches both theory and design of nonlinear systems for a challenging control objective.