Precision Control of Piezoelectric Ultrasonic Motor for Myringotomy With Tube Insertion

Abstract

The current treatment of otitis media with effusion (OME) when medication fails is to surgically insert a grommet tube in the tympanic membrane. A novel precision surgical device has been developed, which allows tube insertion to be accomplished in an office setting. The device leverages on a piezoelectric ultrasonic motor (USM) stage to facilitate the motion sequences for the procedures. The core engine of the device is in the USM motion controller to achieve the high precision, fast response, and repeatability necessary to allow these medical procedures to be efficiently and successfully done with minimum trauma to the patient. This paper focuses on the controller design for the USM to meet the unique set of specifications to apply the surgical device optimally on patient with OME. A model of the USM is first built and identified. A proportionalintegralderivative (PID) controller is used as the main tracking controller with the parameters derived optimally using an linearquadratic regulator (LQR)assisted tuning approach. A sign function compensator acts to remove nonlinear dynamics due mainly to friction and a sliding mode controller further rejects remnant uncertainty and disturbance. The experimental results show that the constituent control components fulfill their respective functions well, and collectively, the composite controller is effective toward delivering the level of control performance to meet the objectives for the medical procedures.