Optimal control of a container crane by a fuzzy logic controller, robustness and stability

The objective of this study concerns the determination of the optimal control strategies of a rotary crane. Such system is represented by a sixth order nonlinear mathematical model. The proposed approach consists of the decomposition of the system into two interconnected subsystems which are linear with respect to their state and control vectors. The non linearities are located in the interconnexion terms. In this context, local feedback gains can be computed by solving, a nonlinear Riccati equation. whereas, the local gains depend on the state vector of the other subsystem. Within this approach, a Takagi Sugeno fuzzy logic system has been constructed in order to identify these gains. Simulation results show that the proposed approach yields to satisfactory performances.