EPACK, INC. — Department of Defense SBIR Phase I: SB152-005

Description

Microelectromechanical systems (MEMS) inertial (motion) sensors are now used for a wide range of consumer and industrial applications, but cant be used for many precision navigation applications because of their inaccuracy. In particular, the measurement (bias) stability of MEMS gyroscopes generally have temperature sensitivities of 10-100 degrees/hour/degree Celsius. This mean that even with small outside temperature chances, these sensors have difficulty achieving the 1 degree/hour instabilities of much larger and more expensive fiber optic gyroscopes. Furthermore, changes in stress (which can also be temperature dependent) also have significant effects on device performance. The proposed environmentally stabilized IMU (eIMU) will address this through improvements in its micromachined thermal/stress isolation package. This package holds the IMU (consisting of 3 gyroscopes and 3 accelerometers) at a constant temperature during operation and isolates them from changing outside stresses. The technical challenges include: (i) further optimizing the package design to eliminate thermal and stress gradients; (ii) eliminating materials and processes which can result in long term sensor drift and; (iii) optimizing the sensor performance and the oven control algorithms.