Decentralized control design and implementation for magnetic levitation systems with extended state observer

This paper focuses on control design and synthesize for a class of magnetic levitation systems, which have a decentralized control for each suspension point. Due to the existence of mechanical coupling among four suspension points, large modeling uncertainties, unpredictable disturbances during the operation, and measurement noises, becomes challenging. To estimate and compensate for the effects of lumped uncertainties, this study employs the extended state observer (ESO) in conjunction with active disturbance rejection control (ADRC). Specifically, a novel ESO is proposed that utilizes output signals and their derivatives to estimate the lumped uncertainties more accurately, which simplifies the convergence proof conditions and has well engineering performance. This article is written in honor of B. M. Chen on the occasion of his 60th birthday. Specifically, this paper is inspired by his pioneering work on composite nonlinear feedback, which combines linear feedback and nonlinear compensator to enhance system performance Chen et al. (IEEE Trans Autom Control, 40:427-439, 2003).