Performance Degradation of the MEMS Vibratory Gyroscope in Harsh Environments

The use of MEMS gyroscopes in a wide range of applications requiring then to function from medium to harsh environments make it necessary to evaluate the performance of MEMS gyroscopes under those conditions. This paper focuses on the effects of elevated temperature and humidity on the performance of MEMS vibratory gyroscopes. Performance of the MEMS gyroscope was evaluated by conducting Highly Accelerated Stress Testing (HAST) on a COTS (commercial-off-the-shelf) single axis MEMS vibratory gyroscope having an operating temperature range from -40(sic)C to +105(sic)C. The gyroscope sensors were exposed to 130 degrees C and 85% relative humidity with a pressure of 33.3 psia or 230 kPa for 96 hours. Pre-baking and post-baking tests were conducted before and after HAST at 125(sic)C for 24 hours respectively. Also, stationary baseline testing (SBT) and rotary baseline testing (RBT) were performed before and after the pre-baking, HAST and post-baking tests to measure any permanent shift during the respective test. A preliminary result shows that the MEMS gyroscope output degraded in the pre-baking test and HAST; while it showed a recovery in post-baking test. After completing the entire test procedure, it was observed that MEMS gyroscope output didn't come back to the original position, and resulted in a permanent output shift of 1.85deg/s.