Adaptive fuzzy dynamic surface control for a class of pure-feedback mechanical systems

An adaptive fuzzy dynamic surface controller is proposed for a class of unstable mechanical systems in purefeedback form. Under the design framework of general dynamic surface control, fuzzy systems are applied to approximate the unknown nonlinearities of the model. Adaptive laws are designed to estimate the weight values of fuzzy systems and unknown parameters. From Lyapunov stability analysis, it is shown that the control strategy can guarantee the semiglobal stability of the closed-loop system. This method eliminates the problem of "explosion of complexity" existing in the traditional backstepping approach and solves the circular design problem existing in pure-feedback control system design. Simulation results show that the control system can overcome the uncertainties and realize the tracking control effectively.