The function of a power steering system is to provide driver with power assist during the car maneuver. without the assist force the wheel would usually be too heavy to rotate manually by the driver, therefore dampening driver’s feel and comfort. In the past, the assist force had been driven by the power of the motor engine transmitted through a hydraulic system. The downsides of a hydraulic system are high energy consumption and lack of flexibility to adjust the assist power according to different driving conditions. More over, the fluids in the hydraulic system have leakage problems which require extra maintenance as the vehicle ages.
More recently, the technology of an electric steering system has been developed. Instead of using the motor engine as the source of power, it uses electricity and electric motor to provide driver with steering assist. The main advantages of an electric system are higher fule efficiency, better driver’s feel and comfort and lessen maintenance. The reduction in energy is possible because power is consumed only when assist force is required. In addition, by using controller logics and sensory devices, the level of assist force can be adjusted according to different road conditions. Lastly, as there is no oil inside an electric system, the leakage problem in hydraullic system is eliminated.