Bird-like tail and wing joints for aerial robots

  • Ruggia, Marco (University of Twente)

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Birds morph in extraordinary ways, enabling highly efficient flight in some species and agile flight in others. This research characterizes wing and tail morphing trough range of motion (RoM) measurements of all major joints in all 3 rotational degrees of freedom (DoF) simultaneously, using motion capture techniques on a pigeon cadaver (Columba livia), something not accomplished before. This data is then used to progress development of bird-like aerial robots. It is speculated, that wing joints tend to move along the edges of RoM to preserve muscular energy in flight. This principle could prove useful for bird-like robots, so a novel robotic twin is developed for further windtunnel/flight studies. It matches a real wing in key aspects, like wrist locking behavior, and elbow ``carrying angle''. It also implements real feathers with matching DoF, leveraging their natural velcro-like behavior. Extensions are planned to add shape memory alloy (SMA) actuation on key DoF's. For the tail, a novel and exceptionally simple mechanism is presented to actuate all 4 DoF (yaw-pitch-roll-spread), with 4 actuators placed in parallel. This is achieved by using a spring-steel flexure, that acts as the bulbus rectricis, together with actuators acting as lateralis caudae and pubocaudalis externus muscles. This is a significant improvement over the typically used series actuator arrangement. Flight tests are underway as of writing of this abstract.