A Maicromachined vibrating ring gyroscope

A new micromachined gyroscope based on a vibrating ring is de­ scribed. The device measures rotation rate or whole angle inertial rotation by monitoring the position of node lines in a vibrating ring. To sense rotation, the ring is electrostatically forced into an ellipti­ cally shaped vibration mode and the position of the node lines are capacitively monitored. When the device is subjected to rotation, the node lines, lag behind the rotation due to the Coriolis force. The control and readout circuitry monitors this lag and develops a cor­ rective 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 al­ lows large amounts of circuitry to be included with the sensor. A resolution of approximately 0.5 °/sec in a 10 Hz bandwidth, limited by the on-chip electronics, has been obtained with this new sensor. Further improvements in the on-chip electronics and sensor materi­ als are expected to push the resolution to below 0.5 ° /sec in a 50 Hz bandwidth.