Study on SelfTakeoff of a Flapping Robot without Running: Influence of the Initial Pitch Angle on the Takeoff Trajectory Recently, research on flapping robots inspired by the behavior of insects and birds has become a focus of attention in the fields of robotics and biomimetics. However, most flapping robots require an operator or an assistance device to take off. The goal of this study was to develop a flapping robot that can achieve selftakeoff without running and can be used like a drone. This paper describes the development and evaluation of the flapping robot developed with this aim. The developed robot can generate a thrust that exceeds its own weight with a simple flapping mechanism and a lightweight design. The airspeed was simulated using the thrust measured with a force sensor and the resistance coefficient estimated in a gliding experiment, and it was found to exceed the minimum airspeed required to achieve takeoff 0.3 s from the onset of flapping. The result of the takeoff experiment demonstrated that takeoff was possible if the initial pitch angle was high. However, the pitch angle decreased immediately after takeoff due to the pitching moment generated by the flapping motion. The moment on the tail wing was not enough for the robot to maintain a horizontal posture at low airspeeds during takeoff. It was concluded that the robot requires a control mechanism for the pitching moment generated by the flapping motion andor accelerators that function without flapping during takeoff, such as hind limbs. Therefore, the parameters required for the design of actuated hind limbs were estimated.

Soft biohybrid morphing wings with feathers underactuated by wrist and finger motion Since the Wright Flyer, engineers have strived to develop flying machines with morphing wings that can control flight as deftly as birds. Birds morph their wing planform parameters simultaneouslyxe2x80x94including sweep, span, and areaxe2x80x94in a way that has proven to be particularly challenging to embody robotically. Previous solutions have primarily centered around the classical aerospace paradigm of controlling every degree of freedom to ensure predictable performance, but underperform compared with birds. To understand how birds accomplish wing morphing, we measured the kinematics of wing flexion and extension in common pigeons, Columba livia. The skeletal and feather kinematics show that the 20 primary and 20 secondary feathers are coordinated via approximately linear transfer functions controlled by wrist and finger motion. To replicate this control principle in a robot, we developed a biohybrid morphing wing with real feathers to understand the underlying design principles. The outcome, PigeonBot, embodies 42 degrees of freedom that control the position of 40 elastically connected feathers via four servoactuated wrist and finger joints. Our flight tests demonstrate that the soft feathered wings morph rapidly and robustly under aerodynamic loading. They not only enable wing morphing but also make robot interactions safer, the wing more robust to crashing, and the wing reparable via xe2x80x9cpreening.xe2x80x9d In flight tests, we found that both asymmetric wrist and finger motion can initiate turn maneuversxe2x80x94evidence that birds may use their fingers to steer in flight.