On the benefit of direct wheel torque control for longitudinal comfort enhancement on uneven roads

Ride comfort is highly affected by road irregularities which cause oscillations in the vertical and longitudinal accelerations. While most studies focus on attenuating the vertical oscillations, a few of them focus on the longitudinal component. Moreover, even fewer in this context compare the control performance of different powertrain architectures, mainly focusing on localized road events. The aim of this research is to demonstrate the effectiveness of in-wheel motor (IWM) architecture for improving vehicle comfort. This paper presents a nonlinear model predictive control (NMPC) strategy, enhanced with the road height profile as preview information. The proposed control architecture is implemented on a vehicle model with two different powertrain configurations: one with four IWMs and another with four conventional on-board motors (OBMs). Performance is assessed across three road profiles of increasing roughness. The results demonstrate that IWM control improves ride comfort significantly compared to the uncontrolled vehicle, achieving an acceleration oscillations reduction of 41% on A-class roads and 31% on C-class roads. On the contrary, the OBM configuration only achieves improvements of 20% and 12%, respectively.