A Micromachined Vibrating Ring Gyroscope

A new micromachined gyroscope based on a vibrating ring is described. The device measures rotation rate or whole angle inertial rotation by monitorying the position of node lines in a vibrating ring. To sense rotation, the ring is electrostatically forced into an elliptically shaped vibration mode and the psoition of the node lines are capacitively monitored. When the device is rotated about the ring center, the node lines, lag behind the rotations due the the Coriolis force. The control and readout circuitry monitors this lag and develops a corrective voltage, that is proportional to the rotation rate, to hold the position of the node lines fixed. The device is fabricated using a low-cost process based on metal electroforming techniques that allows large amounts of circuitry to the included with the sensor for signal readout, compensation, autocalibration, and self-test. A resolution of approximately 0.5deg/sec in a 10Hz bandwidth, limited by the on-chip electronics, has been obtained with this new sensor, Further improvements in the on-chip electronics, the sensor materials, and the sensor design are expected to push he resolution to below 0.5deg/sec in a 50 Hz bandwidth and to improve the temperature performance of the sensor. Recommendations for improving the sensor to meet the requirements for low to medium performance applications are discussed.