Robust adaptive fuzzy control of nonaffine systems guaranteeing transient and steady state error bounds

We consider the prescribed performance tracking problem of single-input single-output, unknown, nonaffine systems in the presence of exogenous disturbances. By prescribed performance, we mean that the tracking error should converge to a predefined arbitrarily small residual set, with convergence rate no less than a prespecified value, exhibiting maximum overshoot less than a sufficiently small preassigned constant. The aforementioned goal is obtained via an output error transformation, which incorporates the desired performance characteristics, and whose boundedness is proven a sufficient condition. Fuzzy systems are utilized to approximate the system uncertainties, and consequently, a smooth robust adaptive fuzzy controller is designed to achieve the target. Simulation studies clarify and verify the approach. Copyright (c) 2012 John Wiley & Sons, Ltd.