Patent ID: 7516642

Claim:
A method for calibrating a distance sensor of a rotary actuator device for controlling a charge cycle valve of an internal combustion engine, wherein the rotary actuator device includes a controllable electric motor having an actuator element for actuating the charge cycle valve, two energy storage means acting on the charge cycle valve in opposite drive directions, a control unit for controlling the electric motor such that the charge cycle valve is transferred from a first end position in which the actuator element driven by a rotor of the electric motor is in a first metastable torque-neutral position associated with the first end position, to a second end position in which at least one of the actuator element and the rotor is in a second metastable torque-neutral position associated with the second end position, comprising the acts of: controlling the electric motor starting from one of the first or second metastable torque-neutral positions so that the rotor is moved out of said one of the first or second metastable torque-neutral positions in at least one direction by a distance; measuring a power consumption by the electric motor during said movement of the rotor out of said one of the first or second metastable torque-neutral positions; and determining a new rotor position for calibration of the distance sensor based on the measured the power consumption by the electric motor.