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6 results on '"Müller, Tonya"'

1. Vision-based flight control and stabilisation in hawkmoths

Author

Müller, Tonya and Taylor, Graham

Subjects
595.78
Abstract

Insects are inherently unstable and therefore rely on sensory feedback in order to maintain flight control and stability. This thesis focuses on how the hawkmoth Manduca sexta uses visual feedback to control and stabilise flight. The analysis is based on extensive sampling of the optomotor responses. I use a virtual reality flight simulator to measure the total moment that the moths generate in response to oscillating wide-field stimuli. The visual stimuli simulate rotations of different amplitudes and frequencies about six different body axes. The moment responses depend upon stimulus amplitude, so are fundamentally non-linear. Nevertheless, for a fixed and suitably small stimulus amplitude, it is possible to fit a linear PID-controller with time delay to each of the optomotor responses. The analysis shows that the moths rely on proportional and integral feedback of angular velocity, with different time delays about different rotation axes. This varying time delay prevents spatial superposition of the optomotor responses to lateral rotational stimuli, meaning that there is no general control law that predicts the responses to an arbitrary lateral stimulus. By combining these empirically derived vision-based flight controllers with linearised flight dynamic models of hovering M. sexta, I evaluate their performance in providing flight stability. This analysis suggests that visual feedback is sufficient to stabilise disturbances associated with rotational stimuli about the horizontal roll and dorso-ventral axes, but is insufficient to stabilise disturbances associated with rotational stimuli about the pitch axis, vertical yaw axis, and longitudinal body axis. The time delay of the optomotor response has a substantial influence on the superposition of the measured optomotor responses, and strongly affects the predicted flight stability. The findings presented in this work have implications for understanding not only the mechanisms and functionality of flight control in hawkmoths, but also the results of past and future investigations into vision-based flight control in insects and flapping-wing air vehicles.

Published
2015

2. In Vivo Time- Resolved Microtomography Reveals the Mechanics of the Blowfly Flight Motor

Author

Walker, Simon M., Schwyn, Daniel A., Mokso, Rajmund, Wicklein, Martina, Müller, Tonya, Doube, Michael, Stampanoni, Marco, Krapp, Holger G., and Taylor, Graham K.

Subjects
animal structures
Abstract

Dipteran flies are amongst the smallest and most agile of flying animals. Their wings are driven indirectly by large power muscles, which cause cyclical deformations of the thorax that are amplified through the intricate wing hinge. Asymmetric flight manoeuvres are controlled by 13 pairs of steering muscles acting directly on the wing articulations. Collectively the steering muscles account for, PLoS Biology, 12 (3), ISSN:1544-9173, ISSN:1545-7885

Published
2014

5. In Vivo Time-Resolved Microtomography Reveals the Mechanics of the Blowfly Flight Motor.

Author

Walker, Simon M., Schwyn, Daniel A., Mokso, Rajmund, Wicklein, Martina, Müller, Tonya, Doube, Michael, Stampanoni, Marco, Krapp, Holger G., and Taylor, Graham K.

Subjects
ANIMAL flight, X-ray computed microtomography, BLOWFLIES, WINGS (Anatomy), MECHANICS (Physics)
Abstract

: Time-resolved X-ray microtomography permits a real-time view of the blowfly in flight at a previously unprecedented level of detail, revealing how the tiny steering muscles work. [ABSTRACT FROM AUTHOR]

Published
2014
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6. In vivo time-resolved microtomography reveals the mechanics of the blowfly flight motor.

Author

Walker SM, Schwyn DA, Mokso R, Wicklein M, Müller T, Doube M, Stampanoni M, Krapp HG, and Taylor GK

Subjects
Animals, Biomechanical Phenomena, Diptera anatomy & histology, Tomography methods, Wings, Animal anatomy & histology, Wings, Animal physiology, Diptera physiology, Flight, Animal
Abstract

Dipteran flies are amongst the smallest and most agile of flying animals. Their wings are driven indirectly by large power muscles, which cause cyclical deformations of the thorax that are amplified through the intricate wing hinge. Asymmetric flight manoeuvres are controlled by 13 pairs of steering muscles acting directly on the wing articulations. Collectively the steering muscles account for <3% of total flight muscle mass, raising the question of how they can modulate the vastly greater output of the power muscles during manoeuvres. Here we present the results of a synchrotron-based study performing micrometre-resolution, time-resolved microtomography on the 145 Hz wingbeat of blowflies. These data represent the first four-dimensional visualizations of an organism's internal movements on sub-millisecond and micrometre scales. This technique allows us to visualize and measure the three-dimensional movements of five of the largest steering muscles, and to place these in the context of the deforming thoracic mechanism that the muscles actuate. Our visualizations show that the steering muscles operate through a diverse range of nonlinear mechanisms, revealing several unexpected features that could not have been identified using any other technique. The tendons of some steering muscles buckle on every wingbeat to accommodate high amplitude movements of the wing hinge. Other steering muscles absorb kinetic energy from an oscillating control linkage, which rotates at low wingbeat amplitude but translates at high wingbeat amplitude. Kinetic energy is distributed differently in these two modes of oscillation, which may play a role in asymmetric power management during flight control. Structural flexibility is known to be important to the aerodynamic efficiency of insect wings, and to the function of their indirect power muscles. We show that it is integral also to the operation of the steering muscles, and so to the functional flexibility of the insect flight motor., Competing Interests: The authors have declared that no competing interests exist.

Published
2014
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