Fuzzy Tuner Based Modified Cascade Control for Electromagnetic Levitation System

This research work presents the modified cascade control scheme using the Fuzzy Tuner. The proposed control structure is implemented for the Electromagnetic Levitation System (EMLS). This EMLS is a group of the highly nonlinear, unstable and electromechanically coupled system. The conventional cascade control with PID and PI controllers as primary and secondary loops is one of the widely used control approaches for the EMLS. However, the constant gains of the conventional cascade control structure may not provide the proper stabilization of the levitating object in the presence of the nonlinearities and the payload disturbances. Hence, Fuzzy Tuner is incorporated for the automatic tuning of the controller gains based on the ITAE criterion. Additionally, the nonlinear estimator is hybridized with the scheme to provide an online estimate of the vertical velocity of the EMLS. Also, the feed-forward compensator is introduced to compress the effect of the variation of the operating conditions. The experimental hardware is utilized to perform the stabilizing control and tracking control operations. The vertical payload disturbance in the range of 0-40 % is considered to check the efficacy of the proposed modified cascade controller.