Adaptive Robust Precision Motion Control of Systems With Unknown Input Dead-Zones: A Case Study With Comparative Experiments

In this paper, the recently developed integrated direct/indirect adaptive robust control (DIARC) for a class of nonlinear systems with unknown input dead-zones is combined with the desired compensation strategy to synthesize practical high-performance motion controllers for precision electrical drive systems having unknown dead-zone effects. The effect of measurement noise is alleviated by replacing noisy state feedback signals with the desired state needed for perfect output tracking. Theoretically, certain guaranteed robust transient performance and steady-state tracking accuracy are achieved even when the overall system may be subjected to parametric uncertainties, time-varying disturbances, and other uncertain nonlinearities. Furthermore, zero steady-state output tracking error is achieved when the system is subjected to unknown parameters and unknown dead-zone nonlinearity only. The proposed algorithm is also experimentally tested on a linear motor drive system preceded by a simulated unknown nonsymmetric dead-zone. The comparative experimental results obtained validate the necessity of compensating for unknown dead-zone effects and the high-performance nature of the proposed approach.