Variable Universe Adaptive Fuzzy Sliding Mode Controller for a Class of Nonlinear System

Abstract

Based on integrating the property of sliding mode control (SMC) with the thought of variable universe in adaptive fuzzy control, a design method of variable universe adaptive fuzzy sliding mode control (FSMC) is proposed. There are two sets of control rule bases. The first set is utilized to approach the equivalent control of SMC. By adjusting the universes of input variables and the membership fuzzy controller of conclusion part in rules on-line, a variable universe adaptive fuzzy control is developed to estimate the equivalent control of SMC control system. The derived adaptive law is applied to adjust the rule parameter for changing the control rules to meet system dynamic. Another set is used to attenuate the switching control of SMC in the sense of heuristic, which ensure the requirement of system stability. Four heuristic control rules are employed to smooth the control law based on the concepts of SMC. We apply the control method to the missile electro-hydraulic servo mechanism. Simulation results verify the validity of the proposed approach.