Abstract
In this paper, a measured current-based method to reproduce realistic steering feel and improve the returnability of steer- by-wire systems is proposed. The key contribution presented here is a novel method to recreate the steering feel in term of force feedback with simple and cheap current sensors. The current sensor is used to measure the steering torque on the rack of steering mechanism. This measured steering torque therefore, includes the overall dynamic effects from road conditions, aligning moments, tire properties and so on. Beside that a free control scheme is proposed to improve returnability as well as the handwheel stability in free motions. The frequency effect of handwheel motion is also introduced. And, this could be useful for torque-map based method. In addition, the physical property the lock-to-lock or steering limitation of mechanical connected steering systems is first carried out for steer-by-wire systems. The lock-to-lock property allows the driver to feel the hard contact when he or she reaches the rotating limitation of handwheel movement. The feasibility of the proposed method was tested with simulation and semi-experiment. A handwheel known as a haptic interface was developed for the experiments. The simulation and semi-experiment were conducted with six subjects. The results have shown that the proposed method offers a cheaper and simpler solution for reproducing realistic steering feel in steer-by-wire systems, and hard contact at lock-tolock position, and improving the stability of handwheel in free motion.
Keywords: steer-by-wire, force feedback, steering feel, driving feel, current sensor, free control, stability, haptic feedback in steer-by-wire, human-vehicle interaction.