Locking mechanism based on flat, overlapping belt, and ultrasonic vibration

Abstract

Locking devices play an important role in robots and assist suits in terms of energy management and miniaturization. In this work, we develop a new locking device for a flat belt that can lock the belt at arbitrary positions and has a simple design that requires no driving parts. According to a mechanical analysis of a flat, overlapped-belt structure, the locked and unlocked states of a flat belt that passes through the structure depend only on the friction coefficient and the contact angle between the belt and the circular cylinder. Moreover, conventional research mentions that the friction coefficient between two objects can be reduced by apply ultrasonic vibration to the objects. The proposed locking mechanism thus uses ultrasonic vibration to vary the friction coefficient and force a flat, overlapped-belt structure to transition from the locked state to the unlocked state. Experiments were conducted by using a prototype device. Upon applying ultrasonic vibration to a locked belt, the belt is unlocked and transmits 14.0% of the tensile force applied to one to the opposite end.