Gain scheduled H-infinity controllers for a two link flexible manipulator

The dynamics of a two link flexible manipulator are highly nonlinear and vary with the configuration of the second link over the operating range of the manipulator. This fact makes it difficult for a single linear time invariant controller to achieve the desired closed-loop specifications. This paper investigates the use of robust gain scheduled H^ controllers for endpoint trajectory tracking of a two link flexible manipulator with the angular position of the second link used as a scheduling parameter. A new method of gain scheduling with guaranteed stability at all frozen intermediate operating points is proposed. The method exploits the explicit and observer based compensator form of H^ controllers resulting from the normalized coprime factor robust stabilization approach. Simulation results corresponding to straight line motion of the tip of the second link are shown to illustrate the use of the proposed method.