Effects of vehicle dynamics on small UAS-gust encounters

Stutz, Colin M.; Hrynuk, John T.; Bohl, Douglas G.

doi:10.1016/j.ast.2023.108679

Cited by 2 publications

(1 citation statement)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For small uncrewed aerial systems (UAS), however, traditional designs leveraging the simplicity of rigidity and decades of optimal aeronautical insight are often accompanied by fragile gust and turbulence response [7][8][9]. Research concerning UAS gust mitigation is therefore a vibrant and important area of inquiry [10][11][12][13] and has also emerged as a possible means for UAS-based kinetic power generation [14][15][16]. The robust response of birds in transient atmospheric conditions motivates bio-inspired mitigation studies.…”

Section: Introductionmentioning

confidence: 99%

Shoulder viscoelasticity in a raptor-inspired model alleviates instability and enhances passive gust rejection

Stanton

2024

Bioinspir. Biomim.

View full text Add to dashboard Cite

Recent experiments with gliding raptors reveal a perplexing dichotomy: remarkably resilient gust rejection, but, at the same time, an exceptionally high degree of longitudinal instability. To resolve this incompatibility, a multiple degree of freedom model is developed with minimal requisite complexity to examine the hypothesis that the bird shoulder joint may embed essential stabilizing and preflexive mechanisms for rejecting rapid perturbations while simplifying and reducing control effort. Thus, the formulation herein is centrally premised upon distinct wing pitch and body pitch angles coupled via a Kelvin-Voigt viscoelastic shoulder joint. The model accurately exhibits empirical gust response of an unstable gliding raptor, generates biologically plausible equilibrium configurations, and the viscoelastic shoulder coupling is shown to drastically alleviate the high degree of instability predicted by conventional linear flight dynamics models. In fact, stability analysis of the model predicts a critical system timescale (the time to double amplitude of a pitch divergence mode) that is commensurate with in vivo measured latency of barn owls (\textit{Tyto alba}). Active gust mitigation is studied by presupposing the owl behaves as an optimal controller. The system is under-actuated and the feedback control law is resolved in the controllable subspace using a Kalman decomposition. Importantly, control-theoretic analysis precisely identifies what discrete gust frequencies may be rapidly and passively rejected versus disturbances requiring feedback control intervention.

show abstract

Section: Introductionmentioning

confidence: 99%

Shoulder viscoelasticity in a raptor-inspired model alleviates instability and enhances passive gust rejection

Stanton

2024

Bioinspir. Biomim.

View full text Add to dashboard Cite

show abstract

Flowfield Analysis of Vortex Interactions During Large Sharp-Edged Gusts

Bonnet,

Smith

2024

AIAA Journal

View full text Add to dashboard Cite

Uncrewed air vehicles in urban environments will have flights during terminal operations that are dominated by strong transient aerodynamics. These vehicles are not only lighter and smaller than traditional rotorcraft and helicopters, but in many instances they may be hybrid configurations with lifting surfaces similar to those of fixed-wing aircraft. These differences require further understanding of the physics of these transient aerodynamics, specifically large-amplitude transverse gusts and the resulting vehicle response, where classic indicial theory is no longer valid. This is crucial to the safety and certification of these air vehicles near buildings and populations. Prior efforts identified that gust responses depart from traditional linear theory when the leading-edge vortex (LEV) forms as a distinct feature and departs from the lifting surface, resulting in flow nonlinearities. This paper expands our understanding of the interactional physics of these nonlinear transverse gusts with flow separation. LEV and trailing-edge vortex (TEV) behavior are correlated, and these vortex interactions are studied to understand the impact on flow separation and subsequent aerodynamic behavior. Larger gust ratios are observed to increase the LEV normal translation, while flow separation is driven by the location and magnitude of the TEV.

show abstract

Effects of vehicle dynamics on small UAS-gust encounters

Cited by 2 publications

References 36 publications

Shoulder viscoelasticity in a raptor-inspired model alleviates instability and enhances passive gust rejection

Shoulder viscoelasticity in a raptor-inspired model alleviates instability and enhances passive gust rejection

Flowfield Analysis of Vortex Interactions During Large Sharp-Edged Gusts

Contact Info

Product

Resources

About