A case study for adaptive robust precision motion control of systems preceded by unknown dead-zones with comparative experiments

The recently proposed integrated direct/indirect adaptive robust controller (DIARC) for a class of nonlinear systems with unknown input dead-zones is combined with desired trajectory compensation to achieve asymptotic stability with excellent tracking performance. The algorithm is tested on a linear motor drive system preceded by a simulated non-symmetric dead-zone which is practically supposed to be unknown. Certain guaranteed robust transient performance and final tracking accuracy are achieved even when the overall system may be subjected to parametric uncertainties, time-varying disturbances and other uncertain nonlinearities. Signal noise that affects the adaptation function is alleviated by replacing the noisy state signal with the desired state feedback. Furthermore, asymptotic output tracking is achieved when there is unknown dead-zone nonlinearity only. Comparative experimental results obtained validate the necessity of dead-zone compensation and the high-effectiveness nature of the proposed approach as well.1