Fuzzy control design for nonlinear dynamic systems using constrained H∞/LTR

Stabilization problems for nonlinear systems are difficult, especially when not all the state are available. This study proposed a combination of constrained H_∞ and loop transfer recovery (LTR) to control nonlinear systems via Takagi-Sugeno fuzzy model. First, the Takagi-Sugeno fuzzy model is employed to represent a nonlinear system. Next, based on the fuzzy model, a Kalman filter is developed. The controller gain is calculated by using constrained H_∞ theory. LTR is then applied to reinforce the robust property of the controller. Simulation results for application to a two-link robot system are demonstrated. The performance of the designed system is assessed in the frequency domain and via the time-domain simulation.