AGAS - Aerodynamic Decelerator Systems Center
This research addressed the development of an autonomous guidance, navigation and control (GN&C) system for a flat solid circular parachute with added limited control authority. This effort was a part of Affordable Guided Airdrop System (AGAS) that integrated a low-cost guidance and control system into fielded cargo air delivery systems to deliver payload in Ultra-Light and Extra-Light weight categories.
The AGAS concept, its architecture, and components had been developed by Vertigo, Inc. A simplified model of parachute was used at the first stage to develop and evaluate the performance of a modified bang-bang control system to steer the AGAS along a pre-specified trajectory towards a desired landing point (Fig.A). Synthesis of optimal control strategy was based on the Pontryagin’s principle of optimality.
The second stage of this research involved the development of a complete six-degree-of-freedom model of AGAS, computer simulation and hardware-in-the-loop setup based on the actual airborne guidance unit (AGU) and pnematic muscle actuators (Fig B).
|Figure A. The AGAS control concept.||Figure B. Hardware setup for hardware-in-the-loop simulation.|
Finally, the complete system was tested at the U.S. Army Yuma Proving Ground, Yuma AZ. It took only 15 drops to tune the developed GN&C algorithms to match the full-scale 500-lb system. The AGAS was first demonstrated to the public during the Precision Airdrop Technology Conference and Demonstration (PATCAD) in the fall of 2001 (Fig.C). During this demonstration, the developed AGAS managed to outperform other same-weight systems including both circular parachutes and parafoils. Released from about 2km altitude above the drop zone, four AGAS systems landed with miss distances of less than 78m (with 100m being the requirement). To better appreciate this result, it should be noted that the four uncontrolled G-12-parachute-based delivery systems released at the same time were spread out within 1.4km from the intended point of impact. Ever since, the AGAS has been demonstrated at each PATCAD (2003, 2005, and 2007).
Nowadays, Capewell Aerial Systems, South Windsor, CT sells this system in four different weight configurations: AGAS-500, AGAS-2000 and AGAS-5000 (Fig.D).
|Figure C. The first demonstration of AGAS at PATCAD-2001.||Figure D. A fielded version of AGAS-2000 AGU.|
Video Clips and Downloads
You are welcome to download and watch several clips below:
- Release and deployment (10.8 Mb, 34 sec.)
- Descent with one control activated (7.5 Mb, 23 sec.)
- Descent with two adjacent controls activated (5.9 Mb, 17 sec.)
- Landing (12.3 Mb, 22 sec.)
This Zip file contains one of the vertical wind profiles gathered at YPG and used in computer simulations. You may download it and then load into MATLAB workspace using the load ('FD03014.zip', '-mat') command (it is a mat-file with the intentionally changed extension).
In addition to the papers, written by the NPS faculty and listed on the Publication page, here are some more papers written by others including the developers of AGAS hardware, Vertigo, Inc.:
Jorgensen, D., and Hickey, M., “The AGAS 2000 Precision Airdrop System,” Proceedings of Infotech@Aerospace, Arlington, Virginia, September 26-29, 2005.
Kothandaraman, G., and Rotea, M., “Simultaneous-Perturbation-Stochastic-Approximation Algorithm for Parachute Parameter Estimation,”Journal of Aircraft, vol.42, no.5, 2005, pp. 1229-1235.
Dellicker, S., Benney, R., LeMoine, D., Brown, G., Gilles, B., and Howard, R. “Steering a Flat Circular Parachute – They Said It Couldn’t Be Done,” Proceedings of the 17th AIAA Aerodynamic Decelerator Systems Technology Conference and Seminar, Monterey, CA, May 19-22, 2003.
Rogers, R., “Aerodynamic Parameter Estimation for Controlled Parachutes,” Proceedings of the AIAA Atmospheric Flight Mechanics Conference and Exhibit, Monterey, California, Aug. 5-8, 2002.
Dellicker, S., Benney, R., and Brown, G., “Guidance and Control for Flat-Circular Parachutes,” Journal of Aircraft, vol.38, no.5, 2001, pp.809-817.
Kelly, K., and Pena, B., “Wind Study and GPS Dropsonde Applicability to Airdrop Testing,” Proceedings of the 16th AIAA Aerodynamic Decelerator Systems Technology Conference and Seminar, Boston, MA, May 21-24, 2001.
Dellicker, S., and Bybee, J., “Low Cost Parachute Guidance, Navigation and Control,” Proceedings of the 15th AIAA Aerodynamic Decelerator Systems Conference, Toulouse, France, June 8-11, 1999.
Brown, G., Haggard, R., Almassy, R., Benney, R., and Dellicker, S., “The Affordable Guided Airdrop System (AGAS),” Proceedings of the 15th AIAA Aerodynamic Decelerator Systems Conference, Toulouse, France, June 8-11, 1999.
Brown, G., Haggard. R., Benney, R., and Rosato, N., “A New Pneumatic Actuator and its Use in Airdrop Applications,” Proceedings of the 15th CAES/AIAA Aerodynamic Decelerator Systems Technology Conference, Toulouse, France, June 8-11, 1999.