Final Report Summary - DCBIF (Flight dynamics and control of birds and insects)
This project aimed to develop an understanding of the dynamics and control of bird and insect flight comparable in its sophistication to the understanding that engineers have of aircraft. To accomplish this, we tackled a set of highly challenging problems by developing a range of exciting new experimental techniques.
Birds and insects are highly visual animals, so we were especially interested to understand how they use vision to stabilize and control their flight. This is of practical as well as academic interest, because operational unmanned air vehicles do not yet use vision to stabilize and control their flight but will likely do so soon. We explored this problem by developing a virtual-reality flight simulator for insects – rather like a miniature Imax cinema, complete with high-speed data projectors, but equipped with a device measuring the tiny forces and torques that the insect exerts in flight. Our results showed that the insects responded to simulated rotations of their visual field by producing torques that were controlled in an appropriate way to effectively stabilize and steer flight. We also showed that by turning their heads, the insects were able to see a much faster range of motions than they could otherwise have done. Interestingly, we found that birds moved their heads similarly in our field experiments with trained eagles and falcons. We are now in the process of applying these insights to the control of small, unmanned air systems.
Observing your own self-motion, whether through vision or any other sense, is only half of the problem of flight control: to do something useful with this information, you must act upon it. We were therefore interested in understanding how birds and insects control their wingbeat, and especially how they control the shapes of their wings, in order to control their flight. We investigated this problem by using high-speed digital video cameras in the lab and field to measure the details of wing movement and deformation in a trained eagle and a range of insects. We also used computational techniques to predict the aerodynamic forces, and found that wing deformation enhanced the aerodynamic lift that an insect could produce for a given mechanical power by a staggering 70%. Finally, we flew the insects in a virtual reality flight arena, and measured how they responded to sudden rotations of their visual environment, allowing us to link our results back to our other work on vision-based flight control. Our results on wing morphing in birds have since inspired the development by a UK company of a small, unmanned air vehicle with wings that change shape in a bird-like fashion to control its flight performance and flight trajectory (video: http://tinyurl.com/njyroqz).
Changes in wing movement and wing deformation can be caused by a variety of different mechanisms, including the passive effects of aerodynamics, inertia and elasticity, and the active effects of musculoskeletal control. We were therefore interested to understand how changes in wing shape and movement were brought about in birds and insects. We accomplished this partly with the aid of our high-speed videos and aerodynamic models, but to explore the inner workings of the insect flight motor in the depth required, we had to develop an entirely new experimental technique. To do this, we teamed up with insect physiologists at Imperial College London, and beamline scientists at the Swiss Light Source. We exposed the insect to x-ray illumination in flight, spinning it around to allow us to see the flight motor from all angles, and thereby causing the insect to try to turn by varying its wingbeat. By combining radiographic images taken from different viewing angles at the same stage of the wingbeat, we were able to reconstruct – in full 3D – the musculoskeletal movements that power and control the wingbeat (video: http://tinyurl.com/nskataz). We now intend to apply these insights to the development of new micromechanical devices.
Birds and insects are highly visual animals, so we were especially interested to understand how they use vision to stabilize and control their flight. This is of practical as well as academic interest, because operational unmanned air vehicles do not yet use vision to stabilize and control their flight but will likely do so soon. We explored this problem by developing a virtual-reality flight simulator for insects – rather like a miniature Imax cinema, complete with high-speed data projectors, but equipped with a device measuring the tiny forces and torques that the insect exerts in flight. Our results showed that the insects responded to simulated rotations of their visual field by producing torques that were controlled in an appropriate way to effectively stabilize and steer flight. We also showed that by turning their heads, the insects were able to see a much faster range of motions than they could otherwise have done. Interestingly, we found that birds moved their heads similarly in our field experiments with trained eagles and falcons. We are now in the process of applying these insights to the control of small, unmanned air systems.
Observing your own self-motion, whether through vision or any other sense, is only half of the problem of flight control: to do something useful with this information, you must act upon it. We were therefore interested in understanding how birds and insects control their wingbeat, and especially how they control the shapes of their wings, in order to control their flight. We investigated this problem by using high-speed digital video cameras in the lab and field to measure the details of wing movement and deformation in a trained eagle and a range of insects. We also used computational techniques to predict the aerodynamic forces, and found that wing deformation enhanced the aerodynamic lift that an insect could produce for a given mechanical power by a staggering 70%. Finally, we flew the insects in a virtual reality flight arena, and measured how they responded to sudden rotations of their visual environment, allowing us to link our results back to our other work on vision-based flight control. Our results on wing morphing in birds have since inspired the development by a UK company of a small, unmanned air vehicle with wings that change shape in a bird-like fashion to control its flight performance and flight trajectory (video: http://tinyurl.com/njyroqz).
Changes in wing movement and wing deformation can be caused by a variety of different mechanisms, including the passive effects of aerodynamics, inertia and elasticity, and the active effects of musculoskeletal control. We were therefore interested to understand how changes in wing shape and movement were brought about in birds and insects. We accomplished this partly with the aid of our high-speed videos and aerodynamic models, but to explore the inner workings of the insect flight motor in the depth required, we had to develop an entirely new experimental technique. To do this, we teamed up with insect physiologists at Imperial College London, and beamline scientists at the Swiss Light Source. We exposed the insect to x-ray illumination in flight, spinning it around to allow us to see the flight motor from all angles, and thereby causing the insect to try to turn by varying its wingbeat. By combining radiographic images taken from different viewing angles at the same stage of the wingbeat, we were able to reconstruct – in full 3D – the musculoskeletal movements that power and control the wingbeat (video: http://tinyurl.com/nskataz). We now intend to apply these insights to the development of new micromechanical devices.