A packaged silicon MEMS vibratory gyroscope for microspacecraft

In this paper, we present recent work on the design, fabrication, and packaging of a silicon Micro-Electro-Mechanical System (MEMS) microgyroscope designed for space applications. A hermetically sealed package that houses the microgyroscope and most of its control electronics has been built and tested. The entire microgyroscope package is approximately 1×1×0.7 inches in dimensions. The rest of the control electronics which includes the drive and lock-in amplifier circuitry are mounted outside the gyro box on a 1×1 inch circuit board. This packaged microgyroscope has a 7 Hz split between its drive and sense mode and has a scale factor of 24 mV/deg/sec, bias stability of 70 deg/hr, angle random walk of 6.3 deg/√hr, and a rate ramp of 0.2 deg/hr/sec. Recent improvements on the fabrication and assembly procedures and microgyroscope design have resulted in clover-leaf structures with matched drive and sense resonant frequency. These new structures have a very small temperature dependent frequency shift of 0.23 Hz/degree for both the drive and sense modes