Miniature Bulk PZT Traveling Wave Ultrasonic Motors for Low-Speed High-Torque Rotary Actuation

To realize applications involving low speed and high torque in the high-performance actuator industry, especially in the aerospace field, we propose a novel 70H traveling wave rotary ultrasonic motor (TRUM) with an outer diameter of 70 mm and an aperture ratio of 53% (the ratio between the aperture and outer diameter). The power transmission mechanism between the stator and the rotor is analyzed, and a method for realizing low-speed–high-torque characteristics of TRUMs is proposed. ANSYS software is used to simulate the modal parameters of the stator, and the ratio β between the normal amplitude and the tangential vibration velocity of the stator is proposed. The larger the value of β, the lower the speed and the higher the torque. Furthermore, two prototype motors are fabricated, namely, 70HA and 70HB. Compared with 70HA, the maximum no-load speed of the improved 70HB (50 rpm) is decreased by 23.1% and the maximum stall torque (2.4 N∙m) is increased by 100%. Besides this, with a smaller mass of 210 g and a higher torque density of 11.43 N∙m/kg, 70HB has fundamentally different mechanical characteristics.

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Robot Hand with Fingers Using Vibration-Type Ultrasonic Motors (Driving Characteristics)

Journal of Robotics and Mechatronics ◽

10.20965/jrm.2003.p0588 ◽

2003 ◽

Vol 15 (6) ◽

pp. 588-595

Author(s):

Kenji Nishibori ◽

◽

Setsuya Kondo ◽

Hirohisa Obata ◽

Shigeru Okuma ◽

...

Keyword(s):

Contact Angle ◽

Contact Force ◽

Cylindrical Body ◽

Robot Hand ◽

Simple Construction ◽

Low Speed ◽

Ultrasonic Motors ◽

Output Torque ◽

Design Value ◽

High Torque

An ultrasonic motor is a promising actuator for robots since it has simple construction, high response, and high torque at low speed. This paper proposes a robot hand using vibrational ultrasonic motors, instead of moving elements, as fingers. This robot hand with three fingers can simultaneously grasp and rotate a cylindrical body. The driving characteristics of the robot hand were examined experimentally under various conditions. It was confirmed that high torque was obtained when the optimum contact angle and contact force of the ultrasonic motors were used. The reduction of output torque is small even when the diameter of the rotational body deviates from the design value.

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An EMG Control System for an Ultrasonic Motor Using a PSoC Microcomputer

Technological Advancements in Biomedicine for Healthcare Applications - Advances in Bioinformatics and Biomedical Engineering ◽

10.4018/978-1-4666-2196-1.ch002 ◽

2012 ◽

pp. 11-17

Author(s):

Yorihiko Yano

Keyword(s):

Control System ◽

Threshold Level ◽

Ultrasonic Motor ◽

Electromagnetic Noise ◽

Elbow Prosthesis ◽

Low Speed ◽

Ultrasonic Motors ◽

Emg Control ◽

High Torque

The author investigated the possibility of developing a myoelectric elbow prosthesis powered by an ultrasonic motor. Ultrasonic motors have some features that make them uniquely suited to powering prosthetics: they deliver high torque under low-speed operation, they are compact in size and they produce no electromagnetic noise. Typically, the threshold-level of an EMG (electromyogram) is adopted as the method for myoelectrically controlling prostheses using a microcomputer. However, this method is not suitable for every prosthesis. Here, the author proposes an EMG control system for a myoelectric elbow prosthesis that uses a PSoC microcomputer combined with an accelerometer to create an ultrasonic motor. The chapter shows that the EMG control system developed by the author effectively controlled the ultrasonic motor.

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