GPS Performance Enhancement for Advanced Space Launch Boosters and Recoverables

Robert E. Ewing, Vincent P. Lewis, David A. Lukaszewski, Frank R. Bletzacker

Abstract:	Of low-Cost integrated Global Positioning System and Inertial measurement Unit (GPS/IMU) navigation systems to meet the demanding space mission requirements associated with advanced launch vehicle systems. The use of fess expensive, low to moderate grade inertial sensors is made possible by Performance enhancement gained through use of GPS. The types of sensors used in the simulated strapdown IMU include fiber optic gyros and silicon accelerometers. These solid state devices are expected to be hiihly reliable and easily producible with low projected unit cost. The sensors are configured in a skewed redundant array as used in fault-tolerant architectures. SimUtatiOn was performed for several mission phases including launch vehicle boost, onorbit coast, and the deorbit, descent and automatic landing Of a recoverable module, without additional navigation aids. GPS code and Carrier loop tracking is used in all mission phases. And the differential GPS correction mode is utilized during autoland. For most cases, a closed-loop, fully-integrated 17-state extended Kalman Filter, in U-D formulation, is utilized to estimate IMU misalignment angles as well as sensor biases inflight. Results are derived from a high-fidelity, Monte Carlo, guidance and navigation error analysis simulation environment developed by Martin Marietta Astronautics Group (MMAG). In addklln to normal trajectory and error analysis models, tht tool has several other unique features, in&IdinQ a complete set of GPS user and satellite models, permitting nominal as well as failure scenarios to be simulated for a variety of IMU and GPS avionics configurations.
Published in:	Proceedings of the 3rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1990) September 19 - 21, 1990 The Broadmoor Hotel Colorado Spring, CO
Pages:	483 - 494
Cite this article:	Ewing, Robert E., Lewis, Vincent P., Lukaszewski, David A., Bletzacker, Frank R., "GPS Performance Enhancement for Advanced Space Launch Boosters and Recoverables," Proceedings of the 3rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1990), Colorado Spring, CO, September 1990, pp. 483-494.
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