US Patent 11420670 Steer-by-wire system and control method thereof

A steer-by-wire system and a control method thereof. A reaction motor generates a reaction in a direction opposite to a direction in which a steering wheel is manipulated by a driver. A current sensor senses a phase current output by the reaction motor. A motor position sensor senses an angle of rotation of the reaction motor. A state and disturbance observer estimates a plurality of state variables and a driver torque by receiving information regarding the phase current and information regarding the angle of rotation of the reaction motor. A reaction controller determines a reaction torque output by the reaction motor, in accordance with the plurality of state variables and the driver torque estimated by the state and disturbance observer. A steering intention of a driver is accurately determined when the torque sensor or the steering angle sensor is not provided or malfunctions.