H-infinity robust control design for an arm manipulator

This paper deals with the application of the optimal H-infinity control des ign technique to derive a controller for a 3 DOF arm manipulator affected b y nonmodeled dynamics, nonlinearities, actuator dynamics and sensor noise. The control objectives were to obtain a robust stable with robust performan ce controlled system. A family of nonparametric models for a finite number of the arm configurations was obtained. Then, a multivariable nominal model was proposed and derived together with additive nonparametric uncertainty bounds. Weighting functions were used to normalize the H-infinity norm of t he uncertainty and to act on the command, sensor, and error signals. Finall y, a controller was computed by solving the corresponding H-infinity optimi zation problem. The controller was tried on the nominal and worst case conf iguration models. The results showed robust stability and robust performanc e of the controlled system.