Adaptive variable universe fuzzy control for a class of strict-feedback systems with unknown dead-zone

In this paper, based on variable universe fuzzy tracking control (VUFC), we present a novel adaptive non-backstepping design algorithm for a class of SISO strict-feedback systems with unknown dead-zone. With some new states variables and coordinate transforms, the state-feedback control of strict-feedback system is converted into the output-feedback control of normal system and observers need to be designed to estimate these indirect un-measurable states. So, we can consider VUFC scheme rather than backstepping scheme. VUFC are mainly based on the changing of contraction and expansion factor to change the universe of the variables to develop the control performance. This new algorithm can improve the accuracy of the system, alleviate tracking error, strong robustness. According to Lyapunov stable theorem analysis, the stability of all the signals in the closed-loop system can be guaranteed and the tracking error is proven to converge to a small neighborhood of the origin. Simulation results are presented to verify the effectiveness of the proposed approach.