A New Control Strategy for Electric Power Steering on Low Friction Roads

作者：Fan Lu; Zhou Bing; Zheng Harry

来源：SAE International Journal of Passenger Cars - Mechanical Systems, 2014, 7(3): 972-980.

DOI：10.4271/2014-01-0083

• Compensation currents
• Control strategies
• Electric power steering
• Fuzzy logic algorithms
• Nonlinear vehicle dynamics model
• Physical testing
• Steering system model
• Tire-road friction

In vehicles equipped with conventional Electric Power Steering (EPS) systems, the steering effort felt by the driver can be unreasonably low when driving on slippery roads. This may lead inexperienced drivers to steer more than what is required in a turn and risk losing control of the vehicle. Thus, it is sensible for tire-road friction to be accounted for in the design of future EPS systems. This paper describes the design of an auxiliary EPS controller that manipulates torque delivery of current EPS systems by supplying its motor with a compensation current controlled by a fuzzy logic algorithm that considers tire-road friction among other factors. Moreover, a steering system model, a nonlinear vehicle dynamics model and a Dugoff tire model are developed in MATLAB/Simulink. Physical testing is conducted to validate the virtual model and confirm that steering torque decreases considerably on low friction roads. Finally, simulation results show that the new EPS assist control strategy successfully increases steering effort under slippery conditions without compromising ease of steering, while ensuring that road feel also increases with decreasing in road friction and/or increasing vehicle speed as an additional safety measure.

• 出版日期2014
• 单位University of Waterloo, Canada; University of Waterloo,Canada