The Permanent Magnet–Electromagnetic Hybrid Suspension (PEMS) system reduces energy consumption and enlarges the levitation gap, but its performance is constrained by strong nonlinearities, parameter variations, and complex disturbances. An Observation Error Constrained Linear Active Disturbance Rejection Control (OEC-LADRC) method is developed, in which the traditional Linear Extended State Observer is reconstructed by introducing an observation-error constraint term, enhancing disturbance-estimation accuracy without increasing observer bandwidth. Stability is established through theoretical analysis, and a PEMS experimental platform based on a medium–low-speed maglev suspension unit is constructed for validation. Experimental results indicate that, compared with LADRC equipped with anti-suction-failure protection, OEC-LADRC reduces the steady-state levitation-gap error by up to 50%, decreases the time-weighted integral of the absolute tracking error by approximately 14–22%, and shortens the recovery time under free-fall impact by 75.51%, demonstrating significantly improved robustness and disturbance suppression under complex operating conditions.
Qin et al. (Thu,) studied this question.