The traveling-wave ultrasonic motor (TWUM) drive offers many distinct advantages but suffers from severe system nonlinearities and parameter variations, especially during speed control. This paper presents a new speed tracking control system for the TWUM drive, which newly incorporates neuro-fuzzy control and direct pulsewidth modulation to solve the problem of nonlinearities and variations. The proposed control system is digitally implemented by a low-cost digital-signal-processor-based microcontroller, hence reducing the system hardware size and cost. Experimental results confirm that the proposed speed tracking controller can offer good steady-state and transient performance.

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High frequency data, Impulse response function, Realized volatility, Trading volume, Vector autoregressive model,

In this paper, a systematic approach to design ultrasonic stepping motors (USMs) using spatially shifted standing vibrations is presented, with emphasis on the combination of the order of vibration mode, the number of spatial phase shifts, the number of electrode divisions and the number of sections to excite a mode. Based on the operating principle, the design equations and constraints are mathematically derived, hence proposing the design procedure. The finite element method is also employed to investigate the vibration of the stator. Moreover, by borrowing the idea of electromagnetic stepping motors, the half-step-operation control is newly applied to this USM so that the step size can be further halved. A 80-step USM is prototyped. The proposed design approach and control scheme are well supported by experimentation.