Fuzzy sliding-mode controllers with applications

This paper concerns the design of robust control systems using sliding-mode control that incorporates a fuzzy tuning technique. The control law superp oses equivalent control, switching control, and fuzzy control. An equivalen t control law is first designed using pole placement. Switching control is then added to guarantee that the state reaches the sliding mode in the pres ence of parameter and disturbance uncertainties. Fuzzy tuning schemes are e mployed to improve control performance and to reduce chattering in the slid ing mode. The practical application of fuzzy logic is proposed here as a co mputational-intelligence approach to engineering problems associated with s liding-mode controllers. The proposed method can have a number of industria l applications including the joint control of a hydraulically actuated mini -excavator as presented in this paper. The control hardware is described to gether with simulated and experimental results. High performance and attenu ated chatter are achieved. The results obtained verify the validity of the proposed control approach to dynamic systems characterized by severe uncert ainties.