Abstract
This paper describes a new type of acoustic rate gyros, which utilizes Coriolis force acting on air particles vibrated by sound. The sensing head of this gyro is an acoustically closed vessel, inside of which is separated into two chambers by a T-shaped separator. A thin and flat sensing channel connecting the two chambers is formed between the upper plate of the separator and an inside wall of the vessel. The two chambers and the sensing channel thus form an acoustic bridge. The sound source of the bridge, which is a small loud speaker mounted on the separator, gives differentially a sinusoidal volume change to the two chambers and vibrates the air in the sensing channel. Two electret condenser microphones are mounted on the top of the vessel to detect the sound pressures at both sides of the sensing channel. Rotation of the sensing head around a vertical axis produces the Coriolis force in the sensing channel and causes phase changes to these sound pressures. The output voltage proportional to the rate of the rotation is obtained by detecting the phase difference between the outputs of the two microphones. Experiments using a prototype gyro with a signal processing circuit showed the accuracy of 1°/s.
