2006 Volume 126 Issue 12 Pages 1667-1677
There are few self-gap-detecting electromagnetic suspension (EMS) systems robust enough against variation of coil resistance. The authors succeeded in providing much robustness against the variation of coil resistance with a self-gap-detecting EMS system. An adaptive control for coil resistance and an exciting voltage compensator for differences between the coil resistances were applied to the self-gap-detecting EMS system. The adaptive control was applied to the feedback controller and the state observer which evaluates gap length and its change rate with respect to time. As a result, it made clear that this self-gap-detecting controller yields more robustness against mass variation to EMS systems than conventional controllers with gap detectors. This paper proposes this new self-gap-detecting technique. The adaptive control and the exciting voltage compensator will be explained. Moreover, the robustness against mass variation will be discussed. The experimental results will show a validity of the proposed technique and a possibility to apply the self-gap-detecting EMS system to practical apparatuses in industrial fields.