Yajie Chen

With the aim of enhancing both the ride comfort and the safety of the vehicle, we propose a new type of suspension with an annular vibration-absorbing structure, and establish a 3-DOF 1/4 vehicle model. The structure parameters and time-delay feedback control parameters are determined by particle swarm optimization algorithms, which take the root mean values of body acceleration, suspension dynamic deflection, and tire dynamic displacement as their optimization objectives. We analyze the stability of the suspension control system to ensure the stability of the time-delay control system through the Routh-Hurwitz stability criterion, characteristic root method, and stability switching method. Then, we compare and analyze the response characteristics of conventional suspension, new suspension without time-delay feedback control, and new suspension with time-delay feedback control under simple harmonic excitation and random excitation. The results show that the new suspension with time-delay feedback control has a significant damping effect on the body under the premise of ensuring the stability of the system.

To improve the overall performance of four-wheel steering vehicles under different working conditions and solve the problem of the unbalanced comprehensive control effect of a single controller, a multi-mode optimal decision control system is proposed based on the linear 2-DOF dynamic model of the vehicle, which can make the vehicle have better performance under different working conditions. The system is composed of multiple controllers, in which the self-tuning dual yaw rate feedback controller can create timely feedback and make adjustments according to the driving state of the vehicle, which is optimal under the condition of a small rotation angle at medium and high speeds. The system can match the corresponding controller according to the optimal performance of different control strategies at different speeds and angles. The simulation results show that the multi-mode optimal selection system can make the vehicle perform optimally under different working conditions, and that comprehensive performance is more prominent than that of a single controller.

To address the contradiction between ride comfort and handling stability, a new vibration-absorbing wheel structure with time-delay feedback control was proposed by applying a time-delay feedback-controlled dynamic vibration absorber to the wheel structure. Using H₂ optimization and the particle swarm optimization algorithm (PSO), the design parameters of the time-delay vibration-absorbing wheel structure were obtained with sprung mass acceleration (SMA), suspension deflection (SD) and dynamic tire deflection (DTD) as the optimization objective functions. The stability interval of the system was analyzed using the Routh–Hurwitz criterion and the Sturm criterion. The vehicle vibration reduction performance of the new vibration-absorbing wheel structure was simulated and verified in the time domain under harmonic excitation and random excitation. The simulation results show this new structure can effectively solve the contradiction between the ride comfort and handling stability. It provides a new technical idea for reducing vehicle vibration.