Research On The Application Of Magneto-rheological Damper In Steer-by-Wire Force Feedback System

The Steer-by-Wire(SBW) system is one part of the Drive-by-Wire(DBW) system that theautomobile industry would focus on in future. A SBW system is one in which the conventionalmechanical linkages between the steering wheel and the front wheel are removed and the system isoperated by electronic actuators. The SBW system has many merits. For example, a vehicle’sweight can be decreased by reducing the number of necessary parts. The danger of driver beingcrushed is eliminated. It permits automatic steering and vehicle stability control to be free. It’s animportant task for SBW system to provide a suitable road feel. Currently, most research on SBWsystem using a motor to implement force feedback. While the control of the motor fails, the force-feedback motor may drag the steering wheel, causing an accident. Meanwhile a requirement of thesteering wheel is able to return to the original position when the driver releases his hands off thesteering wheel. So this paper adopts a mechanism consisted of Magneto-rheological(MR) damperand torsion spring to provide semi-active force feedback.In this paper, the feedback torque of conventional steering system was analyzed. Themathematical model of feedback torque was established. The relationship between the front wheeland feedback torque of steering wheel was obtained using numerical simulation. A SBW systemforce feedback device based on MR damper and torsion spring was raised. The mechanical modelof this device was established.On the basis of above, an experimental system of MR damper and torsion spring mechanismfor SBW system force feedback was developed based on an industrial computer. The experimentalsystem included MR damper, torsion spring, steering wheel, torque sensor, optical encoder, dataacquisition card and programmable power supply. A force feedback software system was designedwhich included the main control module, torque test module, angle measure module, power supplycontrol module, data storage module and real-time calculation module based on the developmenttools of LabVIEW.The MR damper’s static performance, dynamic performance and hysteresis phenomena weretested using the SBW system force feedback experimental platform. The stiffness of the torsionspring was calibrated. The return-to-center ability of torsion spring was analyzed. The steeringwheel curve of feedback torque and turning angle was planned based on road feel evaluation. Experimental results shows that the mechanism of MR damper and torsion spring can be usedin SBW force feedback system. The experimental system can be used for further research oncontrol algorithm.