Parameter convergence of adaptive input-output linearisable systems with application to Chua´s circuits

Verifiable sufficient conditions for parameter convergence of a class of adaptive input-output linearisable systems with unknown parameters, including those affine with the control input, are provided. Certainty-equivalent adaptive control has solved the tracking problem for a wider class of systems; however, parameter convergence has not so far been verified a priori. By taking advantage of the obtained asymptotic tracking stability and the vanishing time derivatives of the estimated parameters, it is found that it can indeed be checked beforehand provided some mild assumptions are satisfied. The results are then applied directly to a Chua´s circuit to demonstrate their utility