Active control of vehicle lateral dynamics through roll stiffness distribution: Simulation and driver-in-the-loop testing

This study investigates the potential of Active Suspension systems to modulate Roll Stiffness Distribution (RSD) with the goal of enhancing vehicle lateral performance and stability. By shifting the suspension’s role beyond conventional vertical dynamics and ride comfort, widely explored in existing literature, the proposed approach leverages Roll Stiffness Distribution between front and rear axles to actively influence handling balance across a broad range of driving conditions. The approach utilizes actuators already integrated into the suspension systems of modern vehicles, maximizing their potential through a dedicated control strategy. A control logic for the active management of RSD is introduced, designed to mitigate understeer or oversteer behavior in real time. System validation is initially performed in a simulation environment using standardized open-loop maneuvers in accordance with ISO protocols (Ramp Steer, Step Steer, Sine with Dwell). The controller is optimized using a Genetic Algorithm (GA) and subsequently validated through Driver-in-the-Loop (DiL) testing, conducted with a sample of 24 drivers at the dynamic simulator DriSMi of Politecnico di Milano. These tests aimed to assess both objective performance and subjective driver perception. Finally, the proposed system was integrated into a vehicle equipped with an Active Rear Steering system to explore the synergies between the two control systems and define their respective domains of effectiveness in lateral dynamics optimization.