The PAVS lab is currently focused on the development of low-cost precision aerial delivery systems and strategies that can bridge the current cost and performance gaps between uncontrolled parachute systems and costly ram-air parafoil systems.
Single Actuator-based Precision Delivery using a Cruciform Parachute
Cruciform (also known as cross) canopies are inexpensive parachute systems that still exhibit good parachute performance characteristics. However, it is important to consider how the parachute can be controlled. Currently, two categories of parachute control exist: asymmetric and symmetric control. Symmetric control enables the modification of the system descent speed. And in the presence of accurate wind predictions, the system can be controlled through riding the various winds to a desired target. Asymmetric control refers to deforming only a portion of the canopy, thereby creating an asymmetric pressure distribution. This asymmetry results in horizontal gliding capabilities.
The cruciform canopy is controlled with a single actuator, making it a highly cost-effective yet accurate aerial delivery method. Canopy heading is controlled with a permanently deformed panel (through suspension line shortening) with the adjacent panel controlled with a servo-actuator. The glide ratio can then be controlled such that when the system is spinning the GR = 0.0, and when the heading is stabilized the asymmetric canopy deformation creates a GR = 0.3-0.4.
Parachute gain tuning was accomplished in the NASA Langley Vertical Spin Tunnel in Hampton, VA. The 20ft diameter vertical wind tunnel provided a unique testing platform in which the system can fall with an unlimited test duration. Real-time tuning was the completed creating a robust heading controller.
Outdoor flight testing has been conducted with a large hexacopter (DJI M600 and GD-1400 X8), Arcturus T-20 fixed wing unmanned aircraft, UH-60 Black Hawk helicopter, and a SkyVan fixed wing aircraft. Guidance results have demonstrated high accuracy even with simple guidance strategies.