Hybrid adaptive fuzzy controllers of robot manipulators with bounds estimation

A hybrid adaptive fuzzy controller comprises a weighted combination of a direct and an indirect adaptive fuzzy controller, with a continuously switched supervisory controller. The direct and indirect adaptive fuzzy controllers allow fuzzy control rules and fuzzy descriptions to be incorporated respectively, to achieve better adaptation speed. In the design of the supervisory controller, the bounds of the unknown robot dynamics are not required; they are adaptively estimated in the Lyapunov sense. Experimental evaluation conducted on a SEIKO TT-3000 SCARA robot shows that the proposed hybrid adaptive fuzzy controller is robust and stable. It also outperforms both the direct and indirect adaptive fuzzy controllers designed by the authors in their previous work in terms of tracking accuracy and the magnitude of control torque required.