New Linear Ultrasonic Micromotor for Precision Mechatronic Systems

This paper presents a new design for a linear ultrasonic micromotor for precision positioning developed by Physik Instrumente (PI). The stator of the ultrasonic motor consists of a rectangular piezoceramic plate. Two sliders, bonded to a spring which presses them against the stator, move along guides integrated in the stator. These motors are characterized by their extremely simple construction. Two prototypes of the motors using a 9x4x1.5 mm and a 16x8x1.5 mm piezoceramic plate have been designed and tested. With an external position sensor and servo-controller, the motors can be driven to positions in the 0.1 μm range. In open-loop mode, repeatable step size is in the micron range. Maximum speed of the motors is around 100 mm/s. In closed-loop mode, speeds in the millimeter per second range are possible. The design and operating characteristics of the prototypes in both openand closed-loop modes are presented in this paper. To obtain the proper stator geometry, FEM software was used and the vibrational behavior of the system was analyzed with a 3D scanning vibrometer. The FEM simulations, as well as the results of the laser vibrometer measurements, will be presented as animations.