Vehicle yaw dynamics control by torque-based assist systems enforcing driver's steering feel constraints

We investigate the control of torque-based steering assist systems for improving yaw rate tracking and vehicle stabilization. As opposed to active front steering systems based on harmonic motors, torque-based steering assist systems are mechanically coupled with the driver. Thus, besides standard vehicle and actuators constraints, specific constraints related to the driver-actuator interaction need to be enforced. These constraints can be formulated to achieve a multiplicity of goals, including avoiding excessive strain in the driver's arms, and preserving the driver's “feel for the road”. In order to achieve high control performance and constraints satisfaction, we implement controllers based on linear and switched model predictive control, where different types of driver's steering feel constraints are enforced. The different controllers are evaluated in simulation maneuvers to analyze their capabilities and the impact of the constraints in terms of vehicle cornering, stabilization, and driver's steering feel.