Longitudinal and Vertical Dynamics Control in In-Wheel Motor Electric Vehicles

Abstract With the increasing adoption of electric vehicles (EVs), in-wheel motor configurations have gained significant attention due to their potential for improved efficiency and controllability. This thesis focuses on the longitudinal dynamics of an in-wheel motor electric vehicle, where a comprehensive simulation model is developed to analyze vehicle behavior under different road conditions, such as bumps and slippery surfaces. The developed model consists of a motor torque source, a road profile generator, and a quarter-car model that considers both longitudinal and vertical dynamics, through enveloping tire model. The system is first simulated without active control to establish baseline performance. A simple longitudinal controller is then introduced, employing a PID-based slip control mechanism that adjusts torque to regulate wheel slip. The impact of the controller on vehicle performance, including traction, stability, and ride comfort, is evaluated under different conditions. Key performance indicators such as road holding index, vertical acceleration, slip error integral , and maximum slip are analyzed to assess the effectiveness of the controller. The results demonstrate that the introduction of the traction control significantly enhances vehicle stability on slippery roads while having a minimal effect on ride comfort. The combined use of longitudinal and vertical controllers further improves comfort but introduces trade-offs in handling. These findings contribute to a better understanding of longitudinal control strategies for in-wheel motor electric vehicles and their real-world applicability.