Steer-by-wire system

A steer-by-wire system mounted in a vehicle, the steer-by-wire system comprising:

• a turning device configured to turn a wheel of the vehicle;
• and
• a steering reaction force control unit configured to control a steering reaction force applied to a steering wheel, wherein:
• the steering reaction force control unit is configured to calculate a plurality of kinds of axial forces with use of different parameters, calculate a final axial force based on the plurality of kinds of axial forces, and generate the steering reaction force corresponding to the final axial force;
• the plurality of kinds of axial forces include a basic axial force that is calculated based on a turning angle of the wheel or a steering angle of the steering wheel, and an under axial force that becomes smaller than the basic axial force during understeer;
• and
• the steering reaction force control unit is configured to calculate a degree of understeer that reflects a difference between the basic axial force and the under axial force during the understeer and to reduce the final axial force during the understeer to a value smaller than the basic axial force by an amount corresponding to the degree of understeer.