State Observers for Sensorless Control of Magnetic Levitation Systems
It addresses the practical problem of eliminating position sensors in magnetic levitation systems, which is important for reducing cost and improving reliability, but the contribution is incremental as it applies existing estimation techniques to a specific domain.
This paper develops state observers for sensorless control of nonlinear magnetic levitation systems, enabling position regulation using only voltage and current measurements. The approach combines parameter estimation-based observers with dynamic regressor extension to reconstruct magnetic flux and estimate mechanical coordinates, achieving globally stabilizing control.
In this paper we address the problem of state observation for sensorless control of nonlinear magnetic levitation systems, that is, the regulation of the position of a levitated object measuring only the voltage and current of the electrical supply. Instrumental for the development of the theory is the use of parameter estimation-based observers, which combined with the dynamic regressor extension and mixing parameter estimation technique, allow the reconstruction of the magnetic flux. With the knowledge of the latter it is shown that the mechanical coordinates can be estimated with suitably tailored nonlinear observers. Replacing the observed states, in a certainty equivalent manner, with a full information globally stabilising law completes the sensorless controller design. We consider one and two-degrees-of-freedom systems that, interestingly, demand totally different mathematical approaches for their solutions. Simulation results are used to illustrate the performance of the proposed schemes.