Bird-Inspired Spatial Flapping Wing Mechanism via Coupled Linkages with Single Actuator
2026-04-09 • Robotics
Robotics
AI summaryⓘ
The authors designed a bird-like flapping wing mechanism using two connected linkages that move with just one motor. One part moves to create the wing’s sweeping motion, while the other part automatically folds and unfolds without extra motors. They developed an easier way to build these complicated linkages based on shapes with certain areas, making the wing’s movements smooth and coordinated. They tested a 3D-printed version that successfully showed the intended flapping and folding actions.
Bennett linkageSpatial single-loop mechanismOne-degree-of-freedomFlapping-wing mechanismKinematic synthesisFour-bar linkagePassive mechanismBio-inspired robotics3D printingLinkage folding
Authors
Daniel Huczala, Sun-Pill Jung, Frank C. Park
Abstract
Spatial single-loop mechanisms such as Bennett linkages offer a unique combination of one-degree-of-freedom actuation and nontrivial spatial trajectories, making them attractive for lightweight bio-inspired robotic design. However, although they appear simple and elegant, the geometric task-based synthesis is rather complicated and often avoided in engineering tasks due to the mathematical complexity involved. This paper presents a bird-inspired flapping-wing mechanism built from two coupled spatial four-bars, driven by a single motor. One linkage is actuated to generate the desired spatial sweeping stroke, while the serially coupled linkage remains unactuated and passively switches between extended and folded wing configurations over the stroke cycle. We introduce a simplified kinematic methodology for constructing Bennett linkages from quadrilaterals that contain a desired surface area and further leverage mechanically induced passive state switching. This architecture realizes a coordinated sweep-and-fold wing motion with a single actuation input, reducing weight and control complexity. A 3D-printed prototype is assembled and tested, demonstrating the intended spatial stroke and passive folding behavior.