An energy-saving strategy for steering-motors of steer-by-wire vehicles

In a steering process, the steering-motor of a steer-by-wire (SBW) vehicle consumes energy. To facilitate energy efficiency analyses, the steeringmotor energy consumption is split into two parts, which correspond to varied and constant steering-wheel angle operating condition, respectively. The former condition is a vehicle operational manoeuvre, in which steering-wheel angle varies continuously, whereas the latter is a constant-radius circular-curve negotiation, in which steering-wheel angle maintains constant. Analysing the relation of steering-wheel angle with a road curvature, we propose an energysaving strategy for steering-motors of SBW vehicles. The energy-saving strategy is featured with a concept, a hydro-mechanical locking device, and an SBW controller for the steering-motor unit. The feasibility and effectiveness of the energy-saving strategy is demonstrated using closed-loop simulations. To implement the closed-loop simulation, we combine the driver, vehicle, and curved road models generated in CarSim software with the steering-motor model and the SBW controller developed in Matlab/Simulink.