Robird wind tunnel test setup design

Robird is a robot bird which mimics flapping motion by two con rod mechanisms per wing which transform motor rotational motion into flapping, i.e. plunging and pitching. The latter caused by introducing a phase shift in-between the motion of the two con rod mechanisms. To gain understanding in the (aero) dynamics of (Ro) birds, a wind tunnel test setup is designed to among others measure aerodynamic loads. In the design, the desired phase shift, typically between 6° and 7°, is fixed actively with a desired accuracy of ±0.1°.A nonlinear model of the 2-DOF setup mechanism is developed in Spacar using a finite element formulation. The model is validated through state space system identification and parameter estimation of the actual setup. To obtain the desirable flapping wing motion an optimal PID controller is designed. Finally, in the wind tunnel experiments, aerodynamic loads are determined by subtracting the reaction forces measured with a 6-DOF force sensor with simulations of inertial loads and stress resultants.