Investigation of powertrain inertia and road loads effects on automotive yawing

Automotive stability control requires models that accurately represent powertrain dynamics and road load effects. Relevant literature widely addresses yaw control using a linear modeling approach, but it does not address these effects on the vehicle's yaw performance. Thus, it lacks the required accuracy to represent real driving maneuvers. This contribution presents an extended two-degree-of-freedom model that includes longitudinal dynamics that cover the vehicle’s powertrain dynamics, road load parameters, and road surface roughness effects. The adopted model is applied to different driving conditions and maneuvers to examine the vehicle yaw response and to compare the extended model with the basic linear one within the established limits in relevant literature. The model results clearly show that engine driving and braking power, powertrain inertias, gear ratios, brake forces, road loads due to air drag and rolling resistance, surface roughness, etc., can significantly influence vehicle yaw response. It also demonstrates the model’s flexibility to account for actual forces and disturbances, which helps develop an accurate yaw moment control strategy. The extended model shows much better potential for controlling vehicle yaw response compared to simplified model results. It includes powertrain dynamics that help to improve vehicle performance in terms of yaw rate and rollover limit. Moreover, the adopted modeling allows for longitudinal speed variation, which reflects real maneuvers. Therefore, the vehicle yawing response is better represented, as the model allows for a shift from current steady-state-based control techniques towards more accurate model-based yaw control techniques.