STEERING SYSTEM

PROBLEM TO BE SOLVED: To provide a simple-structured steering system capable of giving a steering feeling to a driver, stabilizing the behavior of a vehicle, and securing failsafe security. SOLUTION: The steering system is structured so that an operation side shaft 2 coupled mechanically with a steering wheel 1 and a wheel side shaft 4 coupled mechanically with one wheel are coupled together mechanically so that they rotate in a single piece in the first coupling mode, and are coupled mechanically in the second coupling mode in such a way as admitting relative rotation at the set relative rotation angle and generating a single piece rotation when the set relative rotation angle is attained. On the basis of the deviation of the sensing behavior index value corresponding to the change in the vehicle behavior from the target behavior index value corresponding to the sensed operating amount of the steering wheel 1, an actuator is controlled so as to generate a steering force in the first coupling mode when judgement is passed that no steering control is required, and to generate such a steering force as to reduce the deviation in the second coupling mode when judgement is passed that such is required. COPYRIGHT: (C)2006,JPO&NCIPI