Model-Based System Engineering Approach for Steering Feel Simulation for Passenger Vehicles

The basic function of steering system is to control the direction of the vehicle. The driver applies effort on the steering wheel and receives feedback through the steering system as a result of tire to road interaction. This feedback consists of a haptic (force) feedback which is directly felt by the driver and it is termed as steering feel. Precise steering feel gives better driving experience and is decisive factor for customer to buy a vehicle as well as for OEMs in building brand image. Along with steering parameters, suspension and tire parameters also has significant impact on steering feel. In past, modelling of the steering system was done at component level or with simplified vehicle system. Such approaches had not given accurate results of steering feel metric and resulted in incorrect steering design parameter selection. In order to replicate actual vehicle characteristics, complex and detailed modelling of steering, tire and suspension subsystems is necessary. This study proposes high fidelity model-based system engineering approach for prediction of the steering feel. In this methodology, detailed steering model is developed consisting of assist map, steering stiffness, steering gear ratio. Advanced tire, suspension models are built and integrated with 18 degree of freedom chassis model. Simulation is performed according to ISO 7401. The quantities such as steering wheel torque, lateral acceleration, yaw rate, steering wheel angle are measured in simulation. Steering feel metric parameters are extracted from these measured quantities and compared with physical testing measurement. This system engineering based modelling approach resulted in high accuracy results compared with testing data for transient on-centre handling. Proposed approach can be used at initial design stage, sensitivity analysis, optimization of steering design parameters to improve steering feel enabling driving experience to customers.