Actuation system with step motor

An actuation system control process for detection of mechanical clearance, the actuation system including:

• a control system;
• an actuator comprising a drive part and a step motor comprising a rotor and a stator with at least one electric phase;
• an actuated system comprising a controlled element coupled to the drive part;
• and
• an elastic part generating an elastic return force on the rotor of the motor or on the drive part,
• the detection process of mechanical clearance comprising the steps of:
• a) moving the rotor by a predetermined amplitude xi in a direction for displacement of the controlled element;
• b) switching off the current of said at least one phase of the stator;
• c) measuring an induced electric parameter generated on said at least one phase of the stator, and when the value of the electric parameter signals that the rotor has made no return or a return inferior to a predetermined threshold
• d) optionally, moving the rotor by an amplitude yi in an opposite direction to the direction for displacement of the controlled element, where xi>yi,
• e) and repetition of steps (a), (b), (c) and optionally (d) until detection of an induced electric parameter corresponding to return of the rotor resulting from the elastic return force when the mechanical clearance has been overtaken.