Thermal soaring flight of birds and unmanned aerial vehicles

Ákos, Zsuzsa; Nagy, Máté; Leven, Severin; Vicsek, Tamás

doi:10.1088/1748-3182/5/4/045003

Cited by 80 publications

(83 citation statements)

References 32 publications

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“…Other attempts (15,16) have used neural networks and Q-learning to find strategies to center a turbulence-free thermal. Akos et al (17) show that these simple rules fail even in the presence of modest velocity fluctuations modeled as Gaussian white noise, and express the need for strategies that could work in realistic turbulent flows.…”

mentioning

confidence: 99%

Learning to soar in turbulent environments

Reddy

Celani

Sejnowski

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

150

115

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Birds and gliders exploit warm, rising atmospheric currents (thermals) to reach heights comparable to low-lying clouds with a reduced expenditure of energy. This strategy of flight (thermal soaring) is frequently used by migratory birds. Soaring provides a remarkable instance of complex decision making in biology and requires a longterm strategy to effectively use the ascending thermals. Furthermore, the problem is technologically relevant to extend the flying range of autonomous gliders. Thermal soaring is commonly observed in the atmospheric convective boundary layer on warm, sunny days. The formation of thermals unavoidably generates strong turbulent fluctuations, which constitute an essential element of soaring. Here, we approach soaring flight as a problem of learning to navigate complex, highly fluctuating turbulent environments. We simulate the atmospheric boundary layer by numerical models of turbulent convective flow and combine them with model-free, experience-based, reinforcement learning algorithms to train the gliders. For the learned policies in the regimes of moderate and strong turbulence levels, the glider adopts an increasingly conservative policy as turbulence levels increase, quantifying the degree of risk affordable in turbulent environments. Reinforcement learning uncovers those sensorimotor cues that permit effective control over soaring in turbulent environments.thermal soaring | turbulence | navigation | reinforcement learning M igrating birds and gliders use upward wind currents in the atmosphere to gain height while minimizing the energy cost of propulsion by the flapping of the wings or engines (1, 2). This mode of flight, called soaring, has been observed in a variety of birds. For instance, birds of prey use soaring to maintain an elevated vantage point in their search for food (3); migrating storks exploit soaring to cover large distances in their quest for greener pastures (4). Different forms of soaring have been observed. Of particular interest here is thermal soaring, where a bird gains height by using warm air currents (thermals) formed in the atmospheric boundary layer. For both birds and gliders, a crucial part of the thermal soaring is to identify a thermal and to find and maintain its core, where the lift is typically the largest. Once migratory birds have climbed up to the top of a thermal, they glide down to the next thermal and repeat the process, a migration strategy that strongly reduces energy costs (4). Soaring strategies are also important for technological applications, namely, the development of autonomous gliders that can fly large distances with minimal energy consumption (5).Thermals arise as ascending convective plumes driven by the temperature gradient created due to the heating of the earth's surface by the sun (6). Hydrodynamic instabilities and processes that lead to the formation of a thermal inevitably give rise to a turbulent environment characterized by strong, erratic fluctuations (7,8). Birds or gliders attempting to find and maintain a thermal face...

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mentioning

confidence: 99%

Learning to soar in turbulent environments

Reddy

Celani

Sejnowski

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

150

115

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“…According to [2,4] we have the angles (α), the force of lift (L) and speeds in soaring flight see Figures 3 and 4. …”

Section: Biological Inspiration Of Flight Flight Typesmentioning

confidence: 99%

Flight Performance of the Biological Lifting Surface

Prisacariu¹

2017

INCAS BULLETIN

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In the international research, biomimetic lifting surface are analyzed in various aspects: construction, aerodynamics and energy. The specificity of the flying wings determined similarity between the aeromechanical and the biomimetic concepts leading to numerous challenges in terms of construction, aerodynamics and actuation. The Aeromechanics of the biological flight focuses both on the various forms of lifting surfaces and the biomechanical aspects. This article contains a number of references to the biological inspiration of the morphing concept, a brief introduction to the theoretical area of the flying wings and a numerical analysis of biologically similar morphing geometry completed by conclusions and future approaches.

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“…While feathers are not equipped with the ability to sense air currents directly, it is believed that receptors on the follicles of the feathers and changes in pressure distribution on the wing surface are used to provide birds with information about updrafts [36][37][38][39].…”

Section: Future Research Directionsmentioning

confidence: 99%

A Review of Bird-Inspired Flapping Wing Miniature Air Vehicle Designs

Gerdes

Gupta

Wilkerson

2010

Volume 2: 34th Annual Mechanisms and Robotics Conference, Parts a and B

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Physical and aerodynamic characteristics of the bird in flight may offer benefits over typical propeller or rotor driven miniature air vehicle (MAV) locomotion designs in certain types of scenarios. A number of research groups and companies have developed flapping wing vehicles that attempt to harness these benefits. The purpose of this paper is to report different types of flapping wing designs and compare their salient characteristics. For each category, advantages and disadvantages will be discussed. The discussion presented will be limited to miniature-sized flapping wing air vehicles, defined as 10–100 grams total weight. The discussion will be focused primarily on ornithopters which have performed at least one successful test flight. Additionally, this paper is intended to provide a representation of the field of current technology, rather than providing a comprehensive listing of all possible designs. This paper will familiarize a newcomer to the field with existing designs and their distinguishing features. By studying existing designs, future designers will be able to adopt features from other successful designs. This paper also summarizes the design challenges associated with the further advancement of the field and deploying flapping wing vehicles in practice.

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Thermal soaring flight of birds and unmanned aerial vehicles

Cited by 80 publications

References 32 publications

Learning to soar in turbulent environments

Learning to soar in turbulent environments

Flight Performance of the Biological Lifting Surface

A Review of Bird-Inspired Flapping Wing Miniature Air Vehicle Designs

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