Four-Wheel Steering Vehicle Control using Takagi-Sugeno Fuzzy Models

This paper deals with the problem of vehicle active control. The focus is to improve the vehicle stability and handling. Vehicle dynamics is described by a 10-DOF (degree of freedom) model which include lateral, longitudinal, yaw and roll dynamics. Parametric variations (due to the variation of road conditions) and also, a variation of vehicle velocity are taken into account in the controller synthesis. The nonlinear vehicle model is approximated by a Takagi-Sugeno (T-S) fuzzy model with structured parametric uncertainties. State variables are not always available. Thus, fuzzy observer-based algorithm will be proposed to ensure control with performance specifications. Robust pole placement LMI (linear matrix inequalities) conditions are obtained using Lyapunov and H_infin approach, which ensure desired performances of the closed loop system.