Actuator device for a brake-by-wire braking system and braking system

An actuator device for a brake-by-wire braking system, comprising

• an electric motor which has a rotor and a stator,
• a gearing system which is interposed between an actuator output shaft and the electric motor,
• a sensor device which comprises a motor rotation angle sensor for detecting the rotation angle position of the rotor of the electric motor, and
• a control unit which is designed to drive the electric motor to provide a drive torque at the actuator output shaft, and wherein the control unit has a torque determination module which is designed to determine the drive torque at the actuator output shaft caused by the electric motor from the motor parameters of the electric motor,
• wherein the sensor device has an actuator output rotation angle sensor for detecting a rotation angle of the actuator output shaft,
• wherein the torque determination module is designed to compare a rotation angle at the actuator output shaft determined from the sensor signals of the motor rotation angle sensor and a rotation angle determined from the sensor signals of the actuator output rotation angle sensor, to determine a rotation angle difference value based thereon and to determine the drive torque at the actuator output shaft based on the motor parameters of the electric motor and based on the rotation angle difference value.