Abstract
Large scale aerial deployment of miniature sensors in tough environmental conditions requires a deployment device that is lightweight, robust, and steerable. We present a novel samara-inspired autorotating craft that is capable of two flight modes (autorotating mode and diving mode) with an average glide angle of 28.9<inline-formula><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> (1.81 m lateral distance per 1 m loss of altitude) in the former mode. The bidirectional transition between the two modes and directional control is achieved by using only a single actuator. Also, in order to minimize its glide angle, a design optimization methodology is presented for our prototype, diving samara autorotating wing, along with a new cyclic control strategy for directional control of autorotating descent. The dynamic model, simulated in a six degrees-of-freedom environment using the blade element theory, is integrated with genetic algorithm to derive parameters for the wing geometry, flap angle for autorotation, and the proposed cyclic control. The physical prototype autorotates at a descent velocity of 1.43 m/s and rotation speed 4.17 Hz, and is able to transit to diving mode in an average duration of 272 ms to increase its descent velocity by at least 17.6 times. At any point during the dive, it is able to transit back into autorotation in an average duration of 327 ms. Semioutdoor experiments were used to investigate the bidirectional transitions and verify the glide angle (28.9<inline-formula><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula>), which is much improved from the previous prototype (SAW+, 58.4<inline-formula><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula>). Lastly, as a demonstration of a real-life deployment scenario and environmental conditions, the prototypes were dropped from a fixed-wing unmanned aerial vehicle at a suburban test site.
Highlights
I N MANY areas such as military, research, wildlife, and disaster rescue efforts, it is essential to deploy large numbers of lightweight sensors or payloads to desired locations as quickly as possible
samara autorotating wing (SAW) prototypes generally consist of a 3D-printed body that houses the electronic components, and a wing laser-cut from thin balsa wood
It was able to achieve a glide angle of 58.4◦ but when deployed in real-world conditions, it was observed that the trajectory was influenced by strong winds
Summary
I N MANY areas such as military, research, wildlife, and disaster rescue efforts, it is essential to deploy large numbers of lightweight sensors or payloads to desired locations as quickly as possible. In order to eliminate this weakness, two methods are explored: a new flight mode called the diving mode (D-Mode), and a better glide angle The latter involves optimizing the design parameters and improving the cyclic control technique for the craft. We attempt to demonstrate that single-winged autorotating platform can be a capable and exciting contender in the field of micropayload deployment by showing new exciting results and a novel flight mode with highly under actuated control, minimum complexity, and at low cost. Lighter weight and larger wing span, the prototype is able to enter autorotation almost immediately upon a throw and it possesses a descent rate slow enough for meaningful control and glide angle measurement; this proved to become a suitable model to be tested within the limitations of our test facility
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