Implementation of GSA Based Optimal Lead-Lead Controller for Stabilization and Performance Enhancement of a DC Electromagnetic Levitation System

Abstract

In this paper, design, fabrication and testing of voltage controlled (singe loop) single actuator based attraction type levitation system has been reported. A cylindrical shaped hollow ferromagnetic object has been arranged to suspend under E-core electromagnet for some specific applications. The linearized model (transfer function) of voltage controlled electromagnetic levitation system (EMLS) is third order and unstable. Tuning of controller parameters become more difficult for voltage controlled EMLS than current controlled second order EMLS. Usually controllers based on classical technique have been reported for the overall closed loop stabilization. These controllers have a restricted zone of operation and the tracking performance of the controller is found to deteriorate rapidly with increasing deviations from the nominal operating point for which the controller has been designed. As opposed classical techniques, in this work we present an optimization technique that seeks to search for a stabilizing controller of predefined order and structure that also yields good overall performance for a wide air-gap range of operation of the EMLS.  The optimized parameters of cascaded two Lead controllers (Lead-Lead) for single actuator based voltage controlled EMLS are determined using a novel Gravitational Search Algorithm (GSA), implemented in dSPACE platform using MATLAB. Finally stability and performances are tested experimentally.