Meeting Abstract
Beetles, flies, and bees flap their wings by an asynchronous mechanism: Wing strokes are not individually triggered by nerve impulses; rather, delayed stretch-activation allows the flight muscle to oscillate spontaneously when coupled to a resonant load. This type of ‘distributed’ control mechanism has advantages, such as neurological economy and robustness against perturbation, but the implications have not been fully explored. Previous studies found that asynchronous flappers are constrained to a narrow frequency range. We have constructed mathematical and mechanical models of delayed feedback oscillators that display additional complex dynamics that have not been observed in insects. We use high-speed video recordings of house flies to investigate how wing mass affects wing movements. To increase wing mass, we spray-paint the entire wing with a thin layer of spray-on make-up. We attach the fly to a wire and record the wing movements of the tethered fly at 6900 frames per second. We determine wing beat frequency and amplitude from the recordings. By mapping the dynamical parameter space displayed by a real insect we can determine whether the delayed feedback oscillator mechanism is sufficient, or whether additional control mechanisms are employed. We found that flies with increased wing mass are still able to fly and flap their wings. However, adding weight to the wings decreases the frequency of the flapping as well as increasing the amplitude of wing movement during each flap. This observation is consistent with our prediction that the wings behave like a harmonic oscillator and carries implications for the evolution of flight and robotics; a different result would have indicated that the dynamics are more complex or the control mechanism is neurologically rather than mechanically mediated.
