Take-Off Trajectory Optimization of a Pigeon-Inspired Flapping Wing Robot

Birds take off to provide a rapid transition between ground and airborne for predator avoidance and flight initiation. This approach could extend the range of applications for flapping-wing robots. The hard-to-model, unsteady aerodynamics lead to less accurate control of robots. In addition, the success of a take-off is predicated on the need to choose an optimal flight path while sustain the body attitude. In this paper, we present a trajectory optimization algorithm for implementing the take-off of a flapping-wing robot. To accurately model the unsteady aerodynamics, the amplitude of the passive twisting angle was estimated using load cell experiment. Subsequently, a trajectory optimization of the robot's take-off at a height of 1 m was performed with minimum energy consumption as the objective function. We validated this method using a non-linear optimization simulation and demonstrated a flight of a 280 g flapping-wing robot. The average error between the simulation and the actual flight is less than 10%, demonstrating the effectiveness of the trajectory optimization algorithm. Overall, this work paves the way towards the application of flapping-wing robots for autonomous outdoor flight.