All Function Trustworthy Integrated GPS Guidance On a Launch Vehicle Transfer Stage

Stanley C. Maki and Kevin D. Keierleber

Abstract:	A payload transfer stage on an expendable launch vehicle may be required to perform a variety of missions such as low earth orbit direct injection, transfer and payload injection into higher earth orbits, lunar and Mars transfer orbit injection, cargo delivery to Space Station Freedom (SSF), and yet unknown Space Defense Initiative (SDI) payload missions. For an all-function GPS integrated guidance, the GPS must provide attitude determination, in addition to position, velocity, and time elements. Some missions may require orbit durations so long that even precision inertial guidance will have excessive attitude drift. The future trend in space avionics is provision of fault tolerance. The declining cost of avionics relative to vehicle and payload costs is precipitating this trend. GPS antenna configurations, receiver redundancy, redundant inertial sensor configurations, and multiprocessor redundancy are presented for trustworthy integrated GPS inertial guidance. Algorithms and software mapping are discussed for fault-tolerant software operating systems and application software to perform attitude determination and system reconfiguration, in addition to the more common aspects of GPS/inertial position, velocity, and time integration. The verification aspects of modular redundant software are described. Hardware configurations are presented for both near-term and future integrated GPS inertial guidance. Near-term implementation uses line- replaceable units (LRUs), whereas future implementations use line-replaceable modules (LRUs) such as the Multi-Path Redundant Avionics System (MPRAS) with parallel/serial standard interconnecting buses, and an alternative serial standard bus implementation. The aspects of antenna location, thermal conditioning, and avionics hardware installation on a space vehicle are also discussed.
Published in:	Proceedings of the 4th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1991) September 11 - 13, 1991 Albuquerque, NM
Pages:	433 - 442
Cite this article:	Maki, Stanley C., Keierleber, Kevin D., "All Function Trustworthy Integrated GPS Guidance On a Launch Vehicle Transfer Stage," Proceedings of the 4th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1991), Albuquerque, NM, September 1991, pp. 433-442.
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