Adaptive Control with Unknown Parameters in Reference Input

In this paper, model reference adaptive control problem is considered with reference input dependent upon the unknown parameters of the system. Due to the uncertainty in the reference input, conventional linear-in-parameters adaptive controller cannot achieve the control objective without enforcing persistent excitation (PE). A new technique is presented for introducing an excitation signal and regulating its magnitude, dependent upon the convergence of the output tracking and parameter errors. Intelligent excitation ensures parameter convergence similar to conventional PE, but initiates only when necessary. As a result, the regulated output tracks the unknown reference input. Simulations illustrate the theoretical findings