Low cost quartz rate sensors applied to tactical guidance IMUs

The military has shifted its emphasis from strategic weapons to tactical weapons. The challenge in meeting the needs of this shift is to develop a small, low-cost inertial measurement unit (IMU) with sufficient accuracy to meet the needs of modern precision tactical weapons. New instruments, new digital signal processing techniques and the Global Positioning System (GPS) have redefined the cost and performance capability achievable with tactical IMUs. Rockwell International is developing a Digital Quartz IMU (DQI) to meet the needs of this new generation of IMU requirements. The DQI is being designed around an inertial sensor assembly (ISA) being jointly developed by Rockwell International and the Systron Donner Inertial Division of BEI. The ISA utilizes small, batch-fabricated quartz inertial sensors to achieve low cost and small volume. Traditional analog processing of the output of this class of sensor has been replaced with digital processing based on sigma delta analog-to-digital converters to achieve improved performance. This combination of low-cost batch processed sensors with the stability of high-speed digital signal processing produces an IMU that meets the needs of a wide variety of tactical weapons with attractive performance/cost ratios. Prototypes of the DQI design will be completed and evaluated in early 1994. The paper provides an overview of the DQI design and status. A description of the performance objectives and design approach used for the inertial sensor assembly, digital signal processing and mechanical packaging of the DQI are presented