RoboBat: dynamics and control of flapping flight micro aerial vehicles

Flapping flight micro aerial vehicles (MAVs) are of interest to the aerospace and robotics communities for their maneuverability in comparison to tradition fixed wing and rotary aircraft. However they present numerous challenges in the fields of dynamics, stability and control. This thesis examines the dynamics and kinematics of robotic flapping flight, the design and construction of a robotic bat test bed mounted on a 3-DOF pendulum, and subsequent control experiments using the test bed. The robotic bat test bed is capable of exhibiting different wing motions and is used to test the feasibility of controlling the motions of the robotic bat by using the phase differences between coupled nonlinear oscillators called central pattern generators (CPGs). A dynamic model for the robotic bat based on the complex wing kinematics is presented, and the wing kinematic motions themselves are analyzed using a high-speed motion capture system. Mechanical coupling effects which deviate from theoretical assumptions are investigated as well. Open loop experiments analyzing the steady state behavior of the bat's flight with varying phase differences showed a change of the pitch angle while elevation and forward velocity remains constant. Closed loop experiments indeed validate that control dimension reduction is achievable by controlling the phase differences of CPG oscillators. Unstable longitudinal modes are stabilized and controlled using only control of two parameters: phase difference and flapping frequency. Transition between flapping flight and gliding flight is analyzed. This shows promising results regarding the relation between phase differences of wing motions and longitudinal stability, and lays the groundwork for future research and experimentation in flapping flight MAVs