Guidance and control for flat-circular parachutes

The Affordable Guided Airdrop System (AGAS) is being evaluated as a low-cos t alternative for meeting the military's requirements for precision airdrop . Designed to bridge the gap between relatively expensive high-glide ratio parafoil systems and uncontrolled ballistic parachutes, the AGAS concept of fers the benefits of high-altitude parachute releases as well as the potent ial for highly accurate point-of-use delivery of material. The design goal of the AGAS development is to provide a guidance, navigation, and control s ystem that can be placed in line with cargo parachute systems, for example the G-12 flat-circular parachute, and standard delivery containers (A-22) w ithout modifying these fielded systems. The AGAS is required to provide an accuracy of 328 ft (100 m), circular error probable (CEP), with a desired g oal of 164 ft (50 m) CEP. The feasibility of this concept was investigated through modeling and simulation. A three-degree-of-freedom (3DOF) point mas s flight dynamics model, sensor models of a commercial global positioning s ystem (GPS) receiver and magnetic compass, and a model of the control and a ctuator system were incorporated into a Monte Carlo simulation tool. A bang -bang controller was implemented with trajectory tracking algorithms using position and heading information. Flight testing, using a radio-controlled scaled prototype, provided parachute dynamic and control response data to s upport the modeling efforts. The study demonstrated that this concept has t he potential to provide control of previously unguided round parachutes to accuracies of approximately 210 ft (64 m) CEP. The program is now continuin g into the next phase to include the development of a full-scale prototype system for payloads up to 2200 lb (1000 kg).