Unconventional control solutions for small fixed wing unmanned aircraft

Panta, Ashim; Abdel‐Rohman, Mohamed; Marino, Matthew; Watkins, Simon; Fisher, Alex

doi:10.1016/j.paerosci.2018.07.005

Cited by 15 publications

(7 citation statements)

References 50 publications

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“…In addition, CFD models could be used to thoroughly explore the gapped wing design space, enabling more rapid prototype iterations and optimization. CFD models and prototypes could also help evaluate the gapped wing control surface as a method of turbulence mitigation or gust alleviation [48][49][50][51][52][53].…”

Section: Limitations and Future Workmentioning

confidence: 99%

Avian whiffling-inspired gaps provide an alternative method for roll control

Sigrest

Inman

2022

Bioinspir. Biomim.

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Some bird species exhibit a flight behavior known as whiffling, in which the bird flies upside-down during landing, predator evasion, or courtship displays. Flying inverted causes the flight feathers to twist, creating gaps in the wing’s trailing edge. It has been suggested that these gaps decrease lift at a potentially lower energy cost, enabling the bird to maneuver and rapidly descend. Thus, avian whiffling has parallels to an uncrewed aerial vehicle (UAV) using spoilers for rapid descent and ailerons for roll control. However, while whiffling has been previously described in the biological literature, it has yet to directly inspire aerodynamic design. In the current research, we investigated if gaps in a wing’s trailing edge, similar to those caused by feather rotation during whiffling, could provide an effective mechanism for UAV control, particularly rapid descent and banking. To address this question, we performed a wind tunnel test of 3D printed wings with a varying amount of trailing edge gaps and compared the lift and rolling moment coefficients generated by the gapped wings to a traditional spoiler and aileron. Next, we used an analytical analysis to estimate the force and work required to actuate gaps, spoiler, and aileron. Our results showed that gapped wings did not reduce lift as much as a spoiler and required more work. However, we found that at high angles of attack, the gapped wings produced rolling moment coefficients equivalent to upwards aileron deflections of up to 32.7° while requiring substantially less actuation force and work. Thus, while the gapped wings did not provide a noticeable benefit over spoilers for rapid descent, a whiffling-inspired control surface could provide an effective alternative to ailerons for roll control. These findings suggest a novel control mechanism that may be advantageous for small fixed-wing UAVs, particularly energy-constrained aircraft.

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Section: Limitations and Future Workmentioning

confidence: 99%

Avian whiffling-inspired gaps provide an alternative method for roll control

Sigrest

Inman

2022

Bioinspir. Biomim.

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“…If a single alula or asymmetrically arranged alulae are used, roll can be controlled, with an efficiency one order of magnitude better than traditional flaps and ailerons, as shown in Figure 10. The alula could produce a maximum roll moment of 0.036, which is better than the control force of a −20° flap aileron [23][24][25]. Subsequently, Linehan et al [26] constructed a sliding-alula wing (SAW) and carried out a wind-tunnel experiment.…”

Section: Bionic Application Of the Alulamentioning

confidence: 99%

The Progress of Aerodynamic Mechanisms Based on Avian Leading-Edge Alula and Future Study Recommendations

et al. 2021

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Birds in nature have many unique devices to help them acquire excellent flight abilities under various complex flight conditions. One of the unique devices is the leading-edge alula, located at the junction of the arm wing and the hand wing of most birds. It often spreads out during takeoff and landing, probably playing a similar role to high-lift devices in fixed-wing aircraft. This paper analyzed and reviewed the results of current research on leading-edge alula, finding some important factors, such as the complex flapping motions, flexibility, and the plane and section shape of the wing, that have been ignored in current research to a certain extent. These would greatly affect the conclusions obtained. Hence, for a deeper understanding of the aerodynamic mechanisms and functions of the alula, some new study predictions for future research are presented. In addition, the feasible models and methods for further research based on these predictions are discussed and proposed. For example, the higher-accuracy LES or hybrid LES/RANS method and the combinations of these methods with wind-tunnel experiments using PIV technology are recommended.

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“…The control mechanisms and sensing strategies used to maintain this stability are not understood. Studies investigating the control strategies employed by windhovering birds would likely discover novel gust-mitigation techniques that inspire the development of ultra-stable UAVs, a concept that has been the subject of recent research 6 – 15 .…”

Section: Introductionmentioning

confidence: 99%

A method for continuous study of soaring and windhovering birds

Penn

Watkins

et al. 2022

Sci Rep

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Avian flight continues to inspire aircraft designers. Reducing the scale of autonomous aircraft to that of birds and large insects has resulted in new control challenges when attempting to hold steady flight in turbulent atmospheric wind. Some birds, however, are capable of remarkably stable hovering flight in the same conditions. This work describes the development of a wind tunnel configuration that facilitates the study of flapless windhovering (hanging) and soaring bird flight in wind conditions replicating those in nature. Updrafts were generated by flow over replica “hills” and turbulence was introduced through upstream grids, which had already been developed to replicate atmospheric turbulence in prior studies. Successful flight tests with windhovering nankeen kestrels (Falco cenchroides) were conducted, verifying that the facility can support soaring and wind hovering bird flight. The wind tunnel allows the flow characteristics to be carefully controlled and measured, providing great advantages over outdoor flight tests. Also, existing wind tunnels may be readily configured using this method, providing a simpler alternative to the development of dedicated bird flight wind tunnels such as tilting wind tunnels, and the large test section allows for the replication of orographic soaring. This methodology holds promise for future testing investigating the flight behaviour and control responses employed by soaring and windhovering birds.

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Unconventional control solutions for small fixed wing unmanned aircraft

Cited by 15 publications

References 50 publications

Avian whiffling-inspired gaps provide an alternative method for roll control

Avian whiffling-inspired gaps provide an alternative method for roll control

The Progress of Aerodynamic Mechanisms Based on Avian Leading-Edge Alula and Future Study Recommendations

A method for continuous study of soaring and windhovering birds

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