Unified Chassis Control for the Improvement of Agility, Maneuverability, and Lateral Stability

This paper describes a unified chassis control (UCC) strategy for improving agility, maneuverability, and vehicle lateral stability by the integration of active front steering (AFS) and electronic stability control (ESC). The proposed UCC system consists of a supervisor, a control algorithm, and a coordinator. The supervisor determines the target yaw rate and velocity based on control modes that consist of no-control, agility-control, maneuverability-control, and lateral-stability-control modes. These control modes can be determined using indices that are dimensionless numbers to monitor a current driving situation. To achieve the target yaw rate and velocity, the control algorithm determines the desired yaw moment and longitudinal force, respectively. The desired yaw moment and longitudinal force can be generated by the coordination of the AFS and ESC systems. To consider a performance limit of the ESC system and tires, the coordination is designed using the Karush-Kuhn-Tucker (KKT) condition in an optimal manner. Closed-loop simulations with a driver-vehicle-controller system were conducted to investigate the performance of the proposed control strategy using the CarSim vehicle dynamics software and the UCC controller, which was coded using MATLAB/Simulink. Based on our simulation results, we show that the proposed UCC control algorithm improves vehicle motion with respect to agility, maneuverability, and lateral stability, compared with conventional ESC.