Abstract
This work studies the implementation aspects and the expected customer benefits deriving from Active Rear Steering (ARS) technology on a passenger vehicle.
The work is composed of three sections.
The first section is an introduction of the ARS technology, presenting the main implications of implementing this technology onto a passenger vehicle. This includes for example limitations of passive rear suspensions vs. advantages of active solution or package.
The second section is related to the ARS controller design.
First a single track vehicle model is identified, deriving from the above multibody one. Based on the identified model, first a feedforward controller is proposed to improve and personalize the vehicle steady state response to the driver input. Then an oversteer / understeer feedback controller is designed to correct the vehicle dynamic and stability behavior. The oversteer / understeer controller, based on dynamic gain scheduling and yaw rate feedback, results in the expected improvements in agility and stability, till the limit of the rear axle force saturation.
The third section is about performance evaluation in CAE.
An existing multibody vehicle model has been modified to include an ARS actuator and its performances have been compared to the original, passive vehicle model; the improvements in terms of objective measurements have been quantified on standard, full vehicle test maneuvers such as steering pad, slalom or double lane change; typical metrics considered were the entry speed for the double lane change and for the slalom, the minimum steering radius or the maximum speed at a given steering radius.
The testing results are then abstracted to obtain overall indexes for each vehicle attribute, allowing then the quantification of the customer benefits.
Keywords: rear steering, vehicle dynamics, handling, stability, controls