Energy Saving Design and Control of Steering Wheel System of Steering by Wire Vehicle.

The steering wheel system of steering by wire vehicles usually composed of a steering wheel and a road feel motor. This system provides an artificial road feel in the form of torque generated from road feel motor. The motor consistently consumes energy to provide road feel torque during steering, which increases the battery's load and vehicle's fuel consumption. To lessen the energy consumption, a novel design scheme of this steering wheel system is presented in this paper, which adds two variable ratio rotating dampers and a rotating spring. The mathematical model of this system is established according to four steering modes, which are steering, maintaining at a certain angle, and returning and releasing the steering wheel after steering. Control strategies of steering and return modes are developed with the help of PI controller and validated in Simulink simulation. The proportion coefficient of the PI controller is designed as the function of the angular speed of the steering wheel in the steering mode to acquire a better performance. The comparison of energy consumptions in a double lane change is conducted based on Simulink and Carsim co-simulation. The conclusion shows that the new mechanism could save energy greatly and track the steering angle or feel torque at a quite precise.