Method for controlling a power steering system of a road vehicle

A method for controlling a power steering system of a road vehicle, the power steering system including an electric power steering (EPS) subsystem and an electro-hydraulic power steering (EHPS) subsystem for providing force to a steering box of the road vehicle, the method being implemented by a control system of the road vehicle and comprising steps of, after the road vehicle is started:

• activating only the EPS subsystem;
• receiving a speed reading indicating speed of the road vehicle from a speedometer of the road vehicle;
• after the EPS subsystem is activated, further activating the EHPS subsystem when the speed reading indicates that the speed of the road vehicle is not higher than a predetermined speed threshold;
• once the EHPS subsystem is activated, receiving a torque reading indicating torque applied to a steering column of the power steering system from a torque sensor that is disposed on the steering column;
• controlling a hydraulic motor of the EHPS subsystem to rotate at a rotational speed higher than a pre-set rotational speed when the torque reading indicates that the torque is not smaller than a predetermined torque threshold;
• and
• controlling the hydraulic motor of the EHPS subsystem to rotate at a rotational speed lower than the pre-set rotational speed when the torque reading indicates that the torque is smaller than the predetermined torque threshold.