A torque estimator for a traveling wave ultrasonic motor - application to an active claw

Frédéric Giraud (1, 2) , Betty Semail (2, 1)

1 ALCOVE - Collaborative interactive virtual environment
2 L2EP - Laboratoire d’Électrotechnique et d’Électronique de Puissance - ULR 2697

Depending on its electrical to mechanical energy conversion process, the torque on a Travelling Wave Ultrasonic Motor(TWUM)'s shaft is not directly proportional to a measur-able electrical variable, such as current or voltage, but is derived from a complicated process at the stator/rotor interface. The load torque is thus quite unknown, and this can be a disadvantage in applications where a torque limitation is required or a torque measurement is needed. The aim of this article is to come up with a straightforward torque estimator on a TWUM. For that purpose, the motor is modelled, this modelling leads to different estimator strategies. More specifically, we chose a strategy for which a speed sensor is useless, relying only on the stator's resonant behavior. The parameters of the motor needed for the estimator are measured afterwards while some non linearities are identified and taken into account. Several experimental trials are then carried out to check the performance of the estimator. Finally, a claw actuated by a TWUM is presented, because this is a typical application where the knowledge of the torque helps guarantee the safety of the device.

Domaines: Energie électrique; Bibliothèque électronique [cs.DL]

Frédéric Giraud, Betty Semail. A torque estimator for a traveling wave ultrasonic motor - application to an active claw. IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2006, 53 (8), pp.1468 - 1477. ⟨10.1109/TUFFC.2006.1665104⟩. ⟨hal-01110739⟩