Position, Velocity, and Attitude Instrumentation of a Sport Parachute Jumper

Joseph M. Strus, Earl G. Blackwell, Christian A. Gellrich, Michael R. Kirkpatrick and James W. Sinko

Abstract:	SRI International is currently developing a low-cost combined GPS/INS instrumentation package and associated data processing software for several precision navigation applications. The immediate goal for the instrumentation package is to develop a hardware prototype that is compact and light-weight and has the ability to provide stand-alone IMU and GPS data capture for six hours. Furthermore, the package must provide a means to time-tag IMU data to GPS time, and it should be ruggedized to withstand impacts of up to 100 g's. The associated post-mission data processing software uses carrier smoothed differential GPS (DGPS) and an extended Kalman filter to provide position, velocity, and attitude. The first test of the system for functional performance and validation was to gather data and provide a position, velocity, and attitude solution for a sport parachute jumper during free fall, parachute deployment, and the following spiraling dynamics. The paper has two parts. The first part presents the design and architecture for the data capture system and the associated GPS/INS navigation processing software. Component evaluation of several GPS receivers based on reacquisition and dynamic response and the IMU and the embedded processor selection is discussed. The navigation processing software generates DGPS corrections from an L1 reference station and processes raw pseudo- range and delta-range. A single extended Kalman filter combines the IMU and GPS sensor data to form the integrated orientation and position solution. In the second part of the paper, operational considerations and test results of the maneuvering sport jumper during free fall and the associated chute opening are presented. The GPS reradiated signal coupler antenna cable design used for GPS reception while the jumper is in the aircraft overcomes the difficulties associated with GPS reradiation. Finally, methods for deriving GPS-only, and accelerometer-only approximations for swing angle are considered.
Published in:	Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002) September 24 - 27, 2002 Oregon Convention Center Portland, OR
Pages:	881 - 887
Cite this article:	Strus, Joseph M., Blackwell, Earl G., Gellrich, Christian A., Kirkpatrick, Michael R., Sinko, James W., "Position, Velocity, and Attitude Instrumentation of a Sport Parachute Jumper," Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002), Portland, OR, September 2002, pp. 881-887.
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