A novel frequency division control strategy with minimal sensors for commercial vehicle cab suspension using integrated air spring–magnetorheological damper

To address the performance degradation of velocity-dependent semi-active suspension control caused by low-frequency sensor noise and velocity-reconstruction errors, this study develops an integrated magnetorheological damper–air spring (MR–AS) device and a frequency division control (FDC) strategy for commercial vehicle cab suspensions. A three-degree-of-freedom quarter-cab model and a nonlinear MR–AS model incorporating MR hysteresis, air-spring nonlinearity, an auxiliary chamber, and pipeline flow-response dynamics are established. The integrated device is fabricated and experimentally characterized, and its model parameters are identified from harmonic tests. The harmonic balance method is used to interpret the influence of nonlinear air-spring stiffness on the cab frequency response. Guided by the frequency-dependent damping trade-off, FDC determines the damping state from the relative dominance of the low- and high-frequency components of a single measured acceleration signal, thereby avoiding explicit velocity reconstruction. Comparative simulations and real-vehicle road tests demonstrate that FDC suppresses low-frequency resonance while maintaining higher-frequency vibration isolation under practical sensing conditions. Compared with the passive 0 A condition, the FDC reduces the weighted RMS cab accelerations in the x -, y -, and z -directions by 6.9%, 9.9%, and 10.3%, respectively, resulting in an overall vibration reduction of 9.2%. The proposed approach provides a compact and low-complexity solution for semi-active cab-suspension control.