Investigation of the Interaction between the Vehicle Vertical Vibration and Driveline Torsional Vibration Using A Hydro-Pneumatic Limited Bandwidth Active Suspension System 2021-01-0700

Rear wheel drive vehicles have a long driveline using a propeller shaft with two universal joints. Consequently, in this design usage of universal joints within vehicle driveline is inevitable. However, the angularity of the driveshaft resulting from vertical oscillations of the rear axle causes many torsional and bending fluctuations of the driveline. Unfortunately, most of the previously published research work in this area assume the propeller inclination angle is constant under all operating conditions. As a matter of fact, this assumption is not accurate due to the vehicle body attitudes either in pitch or bounce motions. Where the vehicle vibration due to the suspension flexibility, either passive or active type, exists. Moreover, the relative motion between the body and the wheel make this virtualization is so far from the realty in real ground vehicles

In this research work, the hydro-pneumatic limited bandwidth active suspension system with wheelbase preview control is designed to investigate how the active suspension design affects torsional and bending fluctuations of the driveline in comparison with passive suspension. Accordingly, a half car mathematical model with four degrees of freedom ride vibration coupled with the driveline torsional model is constructed and used for these investigations.

The results are generated with two control strategies for the limited bandwidth active suspension, the first one emphasizes on ride comfort and the other emphasizes road holding parameters. On the other hand, two road excitations are used to test the model. The results showed that the virtualization of driveline angularity constant is not suitable for ground vehicle simulation and design. The suspension system type has a significant effect on torsional and bending fluctuations of the driveline. For the limited bandwidth, active suspension type with wheelbase preview control proposed in this work a significant improvement is achieved, in comparison with conventional passive suspension system, through reducing the interaction between the vehicle body vertical vibration and driveline torsional vibration.