Contact modeling for control design of traveling wave ultrasonic motors

摘要

The control applications of traveling wave ultrasonic motors (TWUSMs) suffer from the high nonlinearity and the dead zone caused by friction mechanism, and these challenges are not fully addressed in previous contact models for control design. In this paper, a contact model for control design of TWUSMs is proposed by modeling the friction interface via the static friction and considering the dead zone of vibration amplitude. Firstly, the friction characteristics of contact layer are analyzed and the simulation results clarify that the stick-slip friction can be simplified to the static friction in terms of friction properties and velocity characteristics. Then, the output characteristics of the TWUSM are derived by the static friction and further simplified by the least squares method. Moreover, the dead zone of vibration amplitude is modeled. The effectiveness and feasibility of the proposed model are verified by the simulations and the experiments. The experimental results show that the proposed model not only can effectively simplify the friction characteristics, but also is more accurate than the previous sliding friction based model. The proposed model could be very useful for the design of various controllers of TWUSMs. (C) 2020 Elsevier B.V. All rights reserved.