An Agile Samara-Inspired Single-Actuator Aerial Robot Capable of Autorotation and Diving

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 samarainspired autorotating craft that is capable of two flight modes (autorotating mode and diving mode) with an average glide angle of 28.9 • (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 • ), which is much improved from the previous prototype (SAW+, 58.4 • ). 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.

A self-rotating, single-actuated UAV with extended sensor field of view for autonomous navigation

“…PULSAR has a unique design compared with existing single-actuator UAVs. The dSAW proposed in ( 28 ) used a servo to drive the cyclic pitch of a wing flap during an air-induced self-rotation. Because of the lack of propellers, the dSAW cannot perform powered flight and only works by dropping from a preset altitude.…”

“…For existing self-rotation UAVs ( 20 – 33 ) and other underactuated UAVs with fewer than four propellers ( 40 , 48 – 52 ), the main focuses were on design concept, vehicle configuration, and flying feasibility, whereas agility and the ability to avoid dynamic obstacles were not considered or demonstrated. Only the dSAW proposed in ( 28 ) demonstrated an agile motion that involved only unpowered diving.…”

“…( 25 – 27 ) and Win et al . ( 28 ) estimated the full UAV states by leveraging external position measurements from GPS or radio frequency instruments, limiting their use in GNSS-denied environments. Besides the intended self-rotation in ( 20 – 33 ), unexpected self-rotation could also occur in common quadrotors in case of partial rotor failures.…”

Design, Modeling and Control of a Two Flight Mode Capable Single Wing Rotorcraft With Mid-Air Transition Ability

“…Work done in [4] shows an example of an unpowered monocopter-based lightweight sensor, that can achieve a soft landing due to its shape. Alongside soft landing, the concept of autorotation has also been explored for directional control while in descent using a control surface such as an aileron or flap in [5], [6]. Together with a flap for directional control, monocopters can utilize a motor-driven propeller to achieve lift for the ascent.…”

Modeling, Control and Implementation of Adaptive Reconfigurable ROtary Wings (ARROWs)

“…More severe underactuated aerial systems with only one actuator have been developed and validated to be able to track 3-D position, such as "monospinner" in [26], single actuator microaerial vehicle in [27], and swashplateless microair vehicle in [28]. Instead of actively stabilizing the flight attitude, the nature inspired robotic samara [29], [30], [31] shows a different strategy by making use of its winged body to obtain both extra lift force and passive attitude stability in flight [32], [33], [34].…”