Sliding Mode Control Versus Fractional-Order Sliding Mode Control: Applied to a Magnetic Levitation System

Abstract

This paper focuses on the comparative performances between a Sliding Mode Controller (SMC) and a Fractional-Order SMC (FOSMC). Both the SMC and FOSMC are applied to position control of a ferromagnetic ball against gravity in a Magnetic Levitation (MagLev) system. This paper is the extended version of Roy et al. (in: 2017 Indian control conference (ICC), pp 473–478, 2017). In addition to the contribution of Roy et al. (2017), this paper (i) shows the better potential of an FOSMC over a SMC which is illustrated analytically and (ii) finds the bounds of uncertainty of the parameters of the MagLev system using frequency domain analysis. Experimental results validate the theoretical propositions. The comparative analysis based on these results reveals that the FOSMC performs better than the SMC in terms of tracking accuracy, speed of response, chattering, control effort, and control energy.