Robust force control for a magnetically levitated manipulator using flux density measurement

Abstract

This paper demonstrates, theoretically and experimentally, the idea of magnetic force control in magnetically levitated systems using flux density measurements. The force is determined by measuring the flux density in the airgap from a Hall-effect sensor. A simple magnetic levitation system which consists of a U-shaped electromagnet and a manipulator is developed for demonstration. A state feedback controller and H-infinity controller are used together to increase robustness and speed performance of the force controlled system, and they are implemented in real time using a digital signal processor with 16-bit A/D and D/A converters. Simulation and experimental results for robust stability, disturbance/noise rejection and asymptotic tracking are presented.