Linear fuzzy controller design for dynamic positioning system of surface ships

This paper presents a linear fuzzy controller design for dynamic positioning (DP) system of surface ships using optimal H∞ control techniques. The control technique is used to exterminate the effects of environmental disturbances. First, a Takagi-Sugeno (TS) fuzzy model is used to approximate the nonlinear DP system. Then, linear matrix inequality (LMI) and eigenvalue problem (EVP) methods are employed to solve the robust fuzzy control problem. We use the Lyapunov stability theory to prove the stability of the controller. A positive definite matrix is determined by solving LMI equations using robust control toolbox available in MATLAB. The obtained positive definite matrix proves that the fuzzy controller is stable. Finally, a uniformly ultimately bound (UUB) and control performance is guaranteed. Simulation is carried out, and results are presented to validate the effectiveness and performance of the proposed control system. Copyright © 2015 Inderscience Enterprises Ltd.