Foldable Wings Improve Energy Efficiency of Bio-Inspired Flapping-Wing Robot during Takeoff

The folding function of foldable flapping-wing robots (FFWRs) plays an important role in practical application. In this work, we designed a foldable wing mechanism for studying its energy efficiency improvement potential. The foldable wing mechanism allows the entire wing membrane to fold and expand through the movement of components. We mainly studied the feasible foldable airfoil skeleton, and carried out kinematics and aerodynamic simulations on it, and compared the simulation results with the non-folding airfoil. The results show that when the flapping frequency is the same as 2Hz and the robot forward speed is 5m/s to 10m/s, the average lift force and thrust of the foldable airfoil are smaller than the ones of the non-folding airfoil. The energy loss will be reduced during takeoff of the robot with the foldable wings. The results in this paper can provide a reference for the subsequent wing improvement and flapping-wing robots design.