A new design method and half-step operation for ultrasonic stepping motors

Abstract

In this paper, a systematic design method and a new half-step operation are proposed for ultrasonic stepping motors (USMs) which are based on the principle of spatially shifted standing vibrations. With emphasis on the combination of the order of vibration mode, the number of spatial phase shifts, the number of electrodes, and the number of simultaneously excited electrodes, the design equations and constraints are newly derived, hence, proposing the design procedure. The finite-element method and impedance measurement are also employed to investigate the vibration of the stator. By borrowing the control idea of electromagnetic stepping motors, the half-step operation is newly applied to this USM so that the step size can be further halved. An 80-step USM is prototyped. The proposed design method and half-step operation are well supported by experimentation.

Microstepping control of ultrasonic stepping motors

“…Thus, when the excitation switches from phase A to the simultaneous excitation of both phases A and B, the microstep angle θ µ is equal to the angle shift from the initial nodal line (the zerocrossing point of f a ) to the new nodal line (the zero-crossing point of f ab ). Hence, it yields (10), θ µ can be expressed as…”

“…However, due to the segmentation problem of piezoelectric materials, which are usually made of lead zirconate titanate (PZT), the corresponding step size or the number of steps per revolution is practically limited. Very recently, an attempt has been made to improve the step size of this USSM by borrowing the half-step operation of the conventional electromagnetic stepping motor [10]. Following the idea in [10], the purpose of this paper is to propose and implement the microstepping control of the USSM using the principle of spatially shifted standing vibrations.…”

“…Very recently, an attempt has been made to improve the step size of this USSM by borrowing the half-step operation of the conventional electromagnetic stepping motor [10]. Following the idea in [10], the purpose of this paper is to propose and implement the microstepping control of the USSM using the principle of spatially shifted standing vibrations. Different from the previous half-step operation, which successively conducts single-phase-on and two-phase-on excitation modes, the proposed microstepping control simultaneously varies both the combination of phase excitations and the magnitude of excitations in such a way that the desired step size can be attained.…”

Analytical and numerical modeling of an ultrasonic stepping motor using standing waves

“…In the next paragraphes, the design process for the choice of the motor parameters is described. From [2] and [3], it appears clearly that the number N of steps is a function of the number q of divisions of the piezoelectric ring, the number m of electrodes supplied simultaneously, but also the number of spatial phase shifts p (equivalent to the number of driving phases). It is also specified that there are two modes of motion for the motor: large step and small step.…”

A short cylinder ultrasonic motor with novel excitation mode

“…• Motor design: Along with the rapid development of microelectromechanical systems, the miniaturization of USMs is being actively investigated such as the development of standing-wave stepping USMs [10]- [12] and the development of short cylinder USMs [13]- [15].…”