Abstract:

When a vehicle is moving straight, the driver's acceleration and deceleration operations will cause the vehicle body to pitch. Frequent attitude changes are likely to induce motion sickness in passengers and affect handling experience. To suppress this adverse pitch response, this paper focuses on the problem of vehicle body pitch attitude control under driving and braking conditions, conducts research on modeling and control algorithms based on a fully active suspension system, and verifies the control effect through real-vehicle tests. A four-degree-of-freedom vehicle pitch model is first developed, which incorporates suspension anti-dive and anti-squat characteristics, the location of the longitudinal roll center, and the differences in force transmission mechanisms during driving and braking. The model is validated through simulation using CarMaker. A feedforward–feedback control architecture is then designed, where a nonlinear pitch model is used in place of actual vehicle state feedback, enabling decoupling between drive/brake inputs and vertical road disturbances. This approach effectively suppresses the influence of road unevenness and slope variation on suspension control force output. To achieve a zero pitch angle, a feedforward controller and a PID feedback controller are proposed. An engineering-oriented optimization method is proposed for the feedforward path to suppress high-frequency oscillations in the theoretical control force. Finally, real-vehicle tests are conducted on a prototype vehicle equipped with fully active suspension. Results demonstrate that the proposed control strategy significantly attenuates vehicle pitch response under full-throttle acceleration and emergency braking conditions, reducing pitch angle RMS by up to 89.2% and 77.7%, respectively, thereby enhancing ride comfort and handling stability.

Key words: fully active suspension, pitch model, vehicle attitude control, feedforward–feedback control, real-vehicle experiment