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U.S. Army Yuma Proving Grounds |
Parachute Inflation Phase Estimation and Trajectory Reconstruction -
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Precise knowledge of the dynamic trajectory of a parachute airdrop is a vital component of canopy and suspension system design as well as for model identification and the development of guided systems. Also, Computed Air Release Points or CARPS, used in many airdrop applications to aid in the accurate and safe delivery of critical payloads (such as food and battlefield supplies), require trajectory data to build and refine prediction algorithms.
For most parachute systems, the most chaotic and complex phase of flight is canopy deployment and inflation. During this phase, maintaining GPS lock is often impossible and only the inertial instruments, such as accelerometers and gyros if present, are available to collect trajectory data.
 Maine Aerospace Consulting, under contract  to the Army’s Yuma Proving Grounds in Yuma, Arizona, is developing a Matlab-based tool to reconstruct the dynamic trajectory of a parachute airdrop specifically during the deployment/inflation phase. The algorithm employs an Extended Kalman Estimator to optimally combine potential measurements from GPS (position and velocity), accelerometers and rate gyros to produce an estimate of vehicle position, velocity and attitude. Additionally, since this is a model-based technique, the state vector includes key math model parameters. The algorithm employs inflation models derived from research done at Parks College Parachute Research Group primarily to support the propagation portion of the estimation process. The software can be executed using the Matlab command window or a specially designed Graphical User Interface (GUI).
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