Global Positioning System Denied Navigation of Autonomous Parafoil Systems Using Beacon Measurements From a Single Location

Precision-guided airdrop systems have shown considerable accuracy improvements over more widely used unguided systems through high-quality position, velocity, and time feedback provided by global positioning system (GPS). These systems, like many autonomous vehicles, have become solely dependent on GPS to conduct mission operations. This necessity makes airdrop systems susceptible to GPS blackout in mountainous or urban terrain due to multipathing issues or from signal jamming in active military zones. This work overcomes loss of GPS through an analysis of guidance, navigation and control (GNC) capabilities using a single radio frequency (RF) beacon located at the target. Such a device can be deployed at the target by ground crew on site to retrieve package delivery. Two novel GNC algorithms are presented, which use either range from or direction to a RF beacon. Simulation and experimental flight testing results indicated that beacon-based methods can achieve similar results as GPS-based methods. This technology provides a simple and elegant solution to GPS blackout with best method studied showing only a 21% decrease in landing accuracy in comparison to GPS-based methods.