Development of steer-by-wire system with direct drive torque feedback

This paper describes the design of a Steer-by-Wire system with direct drive torque feedback on the steering wheel. The control scheme does not use any torque sensor: torque information is derived from two observers. Steering feel is greatly improved since the reaction torque sensed by the driver is an image of tire contact patch reaction only. The paper also gives information about the choice of both steer and feedback motors, considering design hints like type, fault-tolerance, redundancy, torque ripple, efficiency, size, weight and cost.