Robust Motion Control of Ultrasonic Motors under Temperature Disturbance
Document Type
Article
Publication Date
4-1-2016
Journal
IEEE Transactions on Industrial Electronics
Volume
63
Issue
4
First Page
2360
Last Page
2368
URL with Digital Object Identifier
10.1109/TIE.2015.2499723
Abstract
This paper presents a practical robust controller that solves the problem of accurate motion control of ultrasonic motors (USMs) over prolonged durations, where temperature increases pose a significant challenge. This paper focuses on USMs with driver circuits that have a single user-controllable input. Prior to developing the robust controller, a nonlinear model of the system was identified by experimentally measuring the temporal relationship between motor speed and temperature to the applied input control signal. A linear approximation of this model was used to design two robust inverse dynamic controllers: one used temperature feedback and the other did not. Both control methods were implemented on a custom designed embedded control system and achieved highly consistent and accurate performance while under load over a range of working frequencies. Step-response experiments (1 rad) demonstrated a rise time of 0.1 s without any overshoot or steady-state error. A normalized RMSE below 3% with a delay of 25 ms was achieved for reference inputs with frequencies up to 1 Hz. This performance was maintained during prolonged continuous dynamic operation of several minutes, despite the great variation in the motor's dynamics due to the temperature effects (over a range of 25 °C-45 °C) and modeling uncertainties.
