- Using fundamental mechanics principles, we interpret the complicated phenomenon of visual stabilization in a flying bird. For birds, mechanisms of visual stabilization are of great significance because blurred vision resulting from vigorous body vibrations caused by wing flapping could seriously jeopardize their survival. Most relevant studies have attributed the bird’s vision stabilization to their nervous and musculoskeletal systems that sense and reduce the vibrations. In our study, however, we found that a flapping passerine exploits a trick to fix the eyes: the production of a lift force exerted posterior to the center of mass of the bird’s body. This trick concurrently results in rotational and translational displacements of the bird's body. Such a complicated body motion does not deteriorate the stability of the eye; instead, the eye remains stabilized because the displacement caused by body translation becomes an offset due to the displacement caused by body rotation. This trick for visual stabilization can offer bio-inspired guidance for engineers to enhance the visual stability of surveillance cameras incorporated in micro aerial vehicles.
