Modelling and control of vehicle corner with in-wheel motor: active suspension control

In-wheel electric powertrains contain motors right inside the wheel hub. This setup has many good points, like making the car handle better, saving energy, and giving designers more freedom. By getting rid of the usual drivetrain parts, in-wheel motors (IWMs) can control torque precisely. This affects the vehicle dynamics including acceleration, braking, pitch, and heave. A lot of studies have looked at how to reduce the up-and-down shaking caused by bumpy roads. But not much attention has been paid to how this interacts with the back-and-forth movements, which can influence how stable and easy to control the car is. Moreover, IWMs introduce additional non negligible mass to the unsprung mass, negatively affecting the suspension filtering capacity of the road disturbances. This study investigates the potential of combining IWMs and active suspension systems to enhance stability and controllability. By leveraging real-time velocity feedback from the sprung and unsprung mass, the suspension system proactively adjusts damping forces to improve ride comfort and road holding. A quarter-car simulation model is developed in Simulink, incorporating Skyhook, Groundhook, and longitudinal PID torque controllers. The Skyhook controller prioritizes passenger comfort by reducing sprung mass acceleration, while the Groundhook controller enhances road holding by minimizing tire load variations. The performance of these controllers is compared against a passive suspension system to evaluate their effectiveness under different conditions. Simulation results across various road profiles, including single bump, multiple bumps, ISO Road, and variable-friction surfaces (μ = 0.8 to 0.17), reveal that the combined vertical controller and torque modulation strategy significantly improves ride quality and handling. Notably, Skyhook and Groundhook controllers outperform passive damping, with Groundhook demonstrating superior road holding, especially on low-friction surfaces. The findings indicate that IWMs, when integrated with active suspension systems and combined control strategies, provide a better solution for optimizing electric vehicle dynamics across diverse real-world conditions.