Adaptive fuzzy nonlinear ℋ∞ tracking control design of a constrained robot system

The problem of robust trajectory tracking control, with a guaranteed H_infin performance, for constrained manipulator systems subject to uncertainties and external disturbances is solved in this paper. A control strategy is developed based on the robot mathematical model and an adaptive fuzzy approach. The adaptive fuzzy control law is based on Takagi-Sugeno model, which is proposed to estimate the behavior of unknown dynamics. A nonlinear H_infin controller is formulated in order to attenuate the effects of estimation errors and external disturbances. A force sensor has been designed and built to measure the forces and torques between the manipulator end-effector and the environment. Finally, experimental results are presented to show the robust tracking performance of a three-link planar manipulator with a straight line path constraint by the proposed approach.