Design of sliding mode controller for magnetic levitation system

Magnetic Levitation System (MLS) is a second order nonlinear system whose applications are widely used in the industry. The objective of the system is the levitation of the objects to a determined height by the magnetization of the coil using the principle of non-contact. The relationship between the magnetic force and the current which is applied to the coil is nonlinear. In this paper, Sliding Mode Controller (SMC) is designed to achieve the desired levitation against uncertainties and nonlinearities of the system. Control law is determined to drive the trajectory towards the sliding surface where MLS becomes invariant to disturbances. Simulations are performed for servo tracking, disturbance rejection tracking, square wave tracking and robustness test. Performance measures are compared with the conventional Proportional Integral Derivative (PID) controller and the results prove that SMC is efficient than PID controller. Experimental observations are observed to confirm the simulation results. (C) 2019 Elsevier Ltd. All rights reserved.