Performance of MEMS inertial sensors

Abstract

Advanced microfabrication techniques have produced small, low-cost silicon inertial sensors of high performance, ruggedness, and inherent symmetry. When integrated with Applications Specific Integrated Circuits (ASIC's), the sensors fit in a 3 cm per side flat pack and operate from a single 5 Vdc supply. They have been evaluated in automotive anti-skid and traction control systems, and in guided munitions. Multi-Chip Module (MCM) versions instruments enable guided munitions to improve the accuracy of the Navy 5"/54 gun platform. These sensors are fabricated using a dissolved wafer process that features single crystal silicon anodically bonded to a glass substrate, resulting in a sensor die size approximately 1 mm. Uncompensated bias and scale factor performance of 0.5/spl deg//s and 1.0% for the gyroscope, and 30 mg and 0.5% for the accelerometer are nominally demonstrated over the temperature range of -40/spl deg/C to +85/spl deg/C. Stability over smaller temperature ranges of 0.5/spl deg/C has surpassed 10/spl deg//hr(0.003/spl deg//s) in overnight (6 hour) tests, while the companion accelerometer nominally demonstrates sub milli-g performance. Angle random walk of 0.25/spl deg///spl radic/h is typical for the gyros with best to date performance of 0.05/spl deg///spl radic/h observed, while the accelerometers provide velocity random walk of 5 cm/s//spl radic/h. When compensated for performance across the temperature range of -40/spl deg/C to +85/spl deg/C, instrument scale factor performance surpasses 200 ppm stability, and bias uncertainty is less than 50/spl deg//hr and 1 mg for the gyro and accelerometer respectively. The robustness of these demonstrated in the ability to survive air guns tests in excess of 60000 g. This paper discusses measured and performance, with the principal focus on recent gyro and accelerometer instrument test results. Associated electronics, controls, and applications issues are also addressed.