At present, most of the seat suspensions of heavy-duty trucks use passive suspension and active suspension. The
passive suspension has gradually failed to meet people's needs in terms of vibration reduction performance, and
the active suspension will consume too much energy. In this paper, a stepped by-pass valve magnetorheological
semi-active suspension based on fuzzy PID control is proposed. The Simulink is used to simulate the system. In
the case of sinusoidal excitation, the results show that this semi-active suspension reduces the vertical acceleration
by 44.36%, the dynamic deflection of the suspension by 29.63% and the dynamic deformation of the tire
by 43.78% compared with the passive suspension. Under the condition of C-level road surface input, the vertical
acceleration of the suspension is reduced by 35.14%, the dynamic deflection of the suspension is reduced by
31.93%, and the dynamic deformation of the tire is reduced by 27.65%.