title: Controlling free flight of a robotic fly using an onboard vision sensor inspired by insect ocelli.
abstract: Scaling a flying robot down to the size of a fly or bee requires advances in manufacturing, sensing and control, and will provide insights into mechanisms used by their biological counterparts. Controlled flight at this scale has previously required external cameras to provide the feedback to regulate the continuous corrective manoeuvres necessary to keep the unstable robot from tumbling. One stabilization mechanism used by flying insects may be to sense the horizon or Sun using the ocelli, a set of three light sensors distinct from the compound eyes. Here, we present an ocelli-inspired visual sensor and use it to stabilize a fly-sized robot. We propose a feedback controller that applies torque in proportion to the angular velocity of the source of light estimated by the ocelli. We demonstrate theoretically and empirically that this is sufficient to stabilize the robot's upright orientation. This constitutes the first known use of onboard sensors at this scale. Dipteran flies use halteres to provide gyroscopic velocity feedback, but it is unknown how other insects such as honeybees stabilize flight without these sensory organs. Our results, using a vehicle of similar size and dynamics to the honeybee, suggest how the ocelli could serve this role.
authors.affiliation: School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA minster@seas.harvard.edu.
authors.forename: Sawyer B
authors.identifier: http://orcid.org/0000-0001-6732-6791
authors.initials: SB
authors.lastname: Fuller
authors.affiliation: School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Karpelson
authors.affiliation: Laboratory for Information and Decision Systems, Massachusetts Institute of Technology, Cambridge, MA 02138, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Censi
authors.affiliation: School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Kevin Y
authors.initials: KY
authors.lastname: Ma
authors.affiliation: School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Wood
mesh_terms: D000401:Aircraft / Q000295:instrumentation*; D000818:Animals; D032701:Biomimetics / Q000295:instrumentation*; D054910:Compound Eye, Arthropod / Q000502:physiology*; D004175:Diptera / Q000502:physiology*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005246:Feedback; D056228:Feedback, Sensory / Q000502:physiology*; D005426:Flight, Animal / Q000502:physiology*; D008904:Miniaturization; D009949:Orientation / Q000502:physiology; D012371:Robotics / Q000295:instrumentation*; D019415:Torque; D014159:Transducers; D014921:Wings, Animal / Q000502:physiology
keywords: biology-inspired robotics; phasic response; stability; velocity feedback