Patent ID: 8093842

Claim:
A position controlled drive mechanism comprising: an electric motor provided with a rotatable shaft; a movable stop operably connected to the rotatable shaft; a sensor for generating a displacement signal indicative of a displacement of the movable stop; and a controller so connected to the electric motor that rotation of the rotatable shaft is controlled thereby, the controller being so connected to the sensor to receive the displacement signal and to calculate therefrom a position of the movable stop; the controller including at least two of the following modes of operation in which the controller is so configured as to: a) control the electric motor to rotate the rotatable shaft to reach a selected position of the movable stop; b) control supply of voltage or of current to the electric motor to maintain a current position of the movable stop, wherein the supply of voltage or current is cut if a large force applied to rotate the shaft prevents maintaining the current position; c) control the electric motor to rotate the rotatable shaft in a selected direction until an external object hinders the rotation of the rotatable shaft; and d) control the electric motor to assist an externally initiated rotation movement of the rotatable shaft detected by the sensor.