A RATE SENSOR FOR SENSING A RATE ON AT LEAST TWO AND PREFERABLY THREE AXES

摘要

A rate sensor for sending applied rate on at least two and preferably three axes includes a vibrating structure (6). Means are provided for vibrating the structure (6) in a Cos 2.theta. carrier mode at a Cost 26 frequency. This carrier mode provides the linear momentum components necessary to couple energy into response modes in every geometric plane. Rotation about one or other of the axes in the plane of the vibrating structure will generate Coriolis forces which cause a rocking motion of the vibrating structure (6) about the same axis at the carrier mode frequency. The vibrating structure (6) has a substantially planar substantially ring or hoop like form shaped and dimensioned to match the frequencies of the Cos 2.theta. mode and rocking mode vibrations in the structure (6) resulting in a resonant amplification of the rocking made vibrations caused by rotations around axes in the plane of the structure (6). Rotation about the third axis normal to the plane of the structure (6) generates Coriolis forces which couple energy into the degenerate Cos 2.theta. response mode. The Cos 2.theta. response and rocking mode vibration amplitudes are proportional to the applied rate and means are provided for detecting the Cos 2.theta. response mode and rocking mode vibration and thereby the applied rate.