Performance analysis of fuzzy control strategy for tractor semi-active seat suspension

This study develops and evaluates a semi-active seat suspension system for tractors using magnetorheological damper (MRD) and fuzzy logic-based control strategies. A five-degree-of-freedom (5-DOF) half-car tractor model is constructed, integrating human-seat dynamics, cab vibration, chassis motion, tire flexibility, and MRD nonlinear hysteresis represented by the Bouc-Wen model. To address uncertainties caused by road roughness, vehicle speed, and human-seat mass variation, a Type-1 fuzzy logic controller (T1FLC) and an interval Type-2 fuzzy logic controller (IT2FLC) are designed. The stability of both controllers is analyzed through phase-plane trajectories. Simulations are performed under random C-F class road excitations, bump inputs at different speeds, and human-seat massranging from 50 to 150 kg. Results show that semi-active control substantially improves ride comfort and reduces suspension dynamic deflection compared with passive suspension. Under random road excitations, the IT2FLC reduces the root mean square (RMS) vertical acceleration by approximately 60% and dynamic deflection by over 50%, effectively mitigating suspension bottoming-out. Under bump excitations, improvements reach 61.27% and 55.94%, respectively. The IT2FLC consistently demonstrates stronger robustness than the T1FLC, especially under highly uncertain or severe road conditions. These findings provide theoretical and engineering support for intelligent vibration-control strategies in agricultural tractor seat suspension systems.