Modelling and Control of a Multi-Mass Ultrasonic Motor for Airborne Applications

Environmental and fire risks together with high maintenance costs are the main drivers in recent years to replace hydraulic actuators in aircrafts by electromechanical actuators. Unluckily, a solution based on electromagnetic motors with reduction gears results in increased weight and electrical peak power of the drive train for typical brake requirements. A promising actuator candidate with high torque and low inertia for airborne applications is the multi-mass ultrasonic motor (MM-USM) derived from the well known travelling-wave type motor (TW-USM). This contribution focuses on the modelling of the MM-USM and proposes a control concept for this motor as drive component of a novel airborne brake actuator: after outlining the operational principle of the motor, a mechanical model is presented, which incorporates sliding and sticking operations of the friction contact. A first validation of the motor model via FEA calculations is supplementing this paper