The Lynchpin—A Novel Geometry for Modular, Tangential, Omnidirectional Flight

Authors Abstract
A novel geometry for a six degrees of freedom (6DOF) unmanned aerial vehicle (UAV) rotary wing aircraft is introduced and a flight mechanical analysis is conducted for an aircraft built in accordance to the thrust vectors of the proposed geometry. Furthermore, the necessary mathematical operations and control schemes are derived to fly an aircraft with the proposed geometry. A system identification of the used propulsion system with the necessary thrust reversal in the form of bidirectional motors and propellers was conducted at a whirl tower. The design of the first prototype aircraft is presented as well as the first flight test results. It could be demonstrated that an aircraft with the thrust vectors oriented according to the proposed geometry works sufficiently and offers unique maneuvering capabilities that cannot be reached with a conventional design. The biggest limiting factor could be identified to be the latency resulting from the time needed to reverse the direction of rotation of the bidirectional propellers. Special operational handling considerations for a manually flown 6DOF vehicle are summarized, and different approaches to control such a vehicle are described. Different mission scenarios and applications for a single aircraft in this design are concluded. Due to the symmetrical properties of the proposed geometry, several aircraft can also be connected at different orientations in flight. Consequently, the possibilities of docking in midair are illustrated, and possible mission scenarios for a group of aircraft, working together collaboratively, are presented. Especially when operated autonomously in a group of aircraft, new possibilities evolve from the capability of the proposed geometry to bond in different orientations.
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Howard, T., Molter, C., Seely, C., and Yee, J., "The Lynchpin—A Novel Geometry for Modular, Tangential, Omnidirectional Flight," SAE Int. J. Aerosp. 16(3):291-303, 2023,
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Mar 15, 2023
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Journal Article