Design and control of the first foldable single-actuator rotary wing micro aerial vehicle

Abstract

The monocopter is a type of micro aerial vehicle largely inspired from the flight of botanical samaras (Acer palmatum). A large section of its fuselage forms the single wing where all its useful aerodynamic forces are generated, making it achieve a highly efficient mode of flight. However, compared to a multi-rotor of similar weight, monocopters can be large and cumbersome for transport, mainly due to their large and rigid wing structure. In this work, a monocopter with a foldable, semi-rigid wing is proposed and its resulting flight performance is studied. The wing is non-rigid when not in flight and relies on centrifugal forces to become straightened during flight. The wing construction uses a special technique for its lightweight and semi-rigid design, and together with a purpose-designed autopilot board, the entire craft can be folded into a compact pocketable form factor, decreasing its footprint by 69%. Furthermore, the proposed craft accomplishes a controllable flight in 5 degrees of freedom by using only one thrust unit. It achieves altitude control by regulating the force generated from the thrust unit throughout multiple rotations. Lateral control is achieved by pulsing the thrust unit at specific instances during each cycle of rotation. A closed-loop feedback control is achieved using a motion-captured camera system, where a hybrid proportional stabilizer controller and proportional-integral position controller are applied. Waypoint tracking, trajectory tracking and flight time tests were performed and analyzed. Overall, the vehicle weighs 69 g, achieves a maximum lateral speed of about 2.37 m s−1, an average power draw of 9.78 W and a flight time of 16 min with its semi-rigid wing.

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

“…On the other hand, Win et al . ( 32 , 33 ) installed the motor on a one-side wing of the UAV. The motor provided a thrust driving the wing to rotate, which produced an aerodynamic lift that controlled the UAV’s altitude.…”

“…The other UAV states other than heading angle still remained unsolved. Full UAV state estimations were made in ( 22 , 24 , 31 – 33 ), but they all relied on external motion capture systems to provide the position and attitude measurements, so they could only be used in indoor instrumented environments. Likewise, Fregene 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. Sun et al .…”

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

“…Note that the higher rotating speed introduces higher angular momentum [40], which requires higher torque generation for attitude stabilization, accordingly. What's more, the lower pitching angles will decrease the torque generation ability based on (29) and (30). As a result, platform (c) in Fig.…”

“…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].…”