Gain-scheduling control of T-S fuzzy systems with actuator saturation

This paper presents a gain-scheduling output feedback control design method for T-S fuzzy systems with actuator saturation. Different from existing control design methods for T-S fuzzy systems, the basic idea of the proposed approach is to transform the T-S fuzzy model with saturation nonlinearity into the form of linear fractional transformation (LFT). Instead of commonly used fuzzy controllers, a gain-scheduled output feedback controller in the LFT form is introduced to stabilize the saturated T-S fuzzy system with guaranteed H∞ performance. The problem of establishing regional stability and performance of the closed-loop nonlinear system are tackled by using robust control techniques. As a result, the conservatism introduced by dealing with the quadratic terms of normalized fuzzy weighting functions can be avoided. The proposed controller synthesis problem is cast as a convex optimization in terms of linear matrix inequalities (LMIs) and can be solved efficiently. An example of balancing the inverted pendulum with bounded actuation is provided to illustrate the effectiveness of the proposed design method.