Robust-Optimal Control of a Nonlinear Two Degree-of-Freedom Helicopter

This paper presents the nonlinear robust-optimal control for the attitudes of a two-degree-of-freedom (2DOF) helicopter. First, a Takagi-Sugeno (T-S) fuzzy model is employed to approximate the nonlinear 2DOF helicopter. The LMI-based relaxed stability conditions are applied to design the nonlinear fuzzy controller. Using the method of parallel distributed compensator (PDC), the nonlinear fuzzy controller regulates the input voltage of two DC motors such that the attitudes of an experimental helicopter are tracked. Computer simulations and experiment results demonstrate the effectiveness of the nonlinear flight control.