Simulator Development for Steer-by-Wire Concept Evaluation 2019-26-0099

In the recent years steering feel characteristics have emerged as one of the important brand image attributes of automotive OEMs. Since past few decades, the hydraulic assisted steering system (HPAS) on which lot of research was done to tune the steering feel has been taken over by electric power assisted steering (EPAS) system. The EPAS primarily uses an electric motor controlled by an electronic control unit to assist the driver in maneuvering the vehicle. The next big leap in the steering system advancement is steer-by-wire (SbW) technology where the mechanical linkage between the steering wheel and the road wheels is eliminated. The advantages of this system are ease to use, elimination of noise-vibration-harshness of steering system caused by road forces, modularly of steering system for packaging, improved visibility to front-end displays and road ahead and a fun to drive concept. The main challenge of a SbW system is generate the steering feel experienced as in the case of conventional power assisted steering system. The main objective of present study is to develop steering simulator which is capable of reproducing the steering feel with SbW technology similar to that experienced in conventional EPAS system to meet the customers’ requirement.

For this purpose 1D AMESIM® based EPAS system model including 15 degrees of freedom chassis model integrated with suspension system, tire model and road- tire interaction model is developed. The model is validated with static and dynamic lock-to-lock test cases followed by steering effort(s)/torque versus steering wheel angle map generation for different vehicle speeds. This map is further used as an input to Matlab-Simulink® and PreScan® based hardware-in-loop steering simulator. The hardware consist of steering wheel, motor, spring, bearings and accelerator-braking-clutch controls.

PreScan® software was used for visualization while Matlab-Simulink® based model was utilized for vehicle dynamics model and control strategy development. Based on driver inputs a force feedback is provided by motor to the steering wheel. Spring force and saturation limit of hardware were modified dynamically so that with varying steering wheel angle and vehicle speed desired steering feel is achieved. The potential use developed simulator is to design and developed robust control strategy for SbW technology for autonomous and electric vehicle applications.