Nonparametric robust adaptive controller for tracking AMB systems

This paper presents a nonparametric robust adaptive controller for precisely tracking a nonlinear active magnetic bearing (AMB) system on the axial direction. The nonlinearities of AMB systems are approximated using a nonparametric method, based on which the controller is designed based on the well known backstepping procedure. It is shown that when we only estimate the bound, instead of all individuals, of the unknown weights in the nonparametric approximation, less parameters are required to be adjusted in designing the online control law. By doing this, the computational burden and the performance of the controller can be significantly lightened. The convergence of the proposed control law is proven under the Lyapunov synthesis, and the effectiveness is verified and demonstrated by simulation results.