The parallel crank-rocker flapping mechanism: an insect-inspired design for micro air vehicles

This paper presents a novel micro air vehicle (MAV) design that seeks to reproduce the unsteady aerodynamics of insects in their natural flight. The challenge of developing an MAV capable of hovering and maneuvering through indoor environments has led to bio-inspired flapping propulsion being considered instead of conventional fixed or rotary winged flight. Insects greatly outperform these conventional flight platforms by exploiting several unsteady aerodynamic phenomena. Therefore, reproducing insect aerodynamics by mimicking their complex wing kinematics with a miniature flying robot has significant benefits in terms of flight performance. However, insect wing kinematics are extremely complex and replicating them requires optimal design of the actuation and flapping mechanism system. A novel flapping mechanism based on parallel crank-rockers has been designed that accurately reproduces the wing kinematics employed by insects and also offers control for flight maneuvers. The mechanism has been developed into an experimental prototype with MAV scale wings (75 mm long). High-speed camera footage of the non-airborne prototype showed that its wing kinematics closely matched desired values, but that the wing beat frequency of 5.6 Hz was below the predicted value of 15 Hz. Aerodynamic testing of the prototype in hovering conditions was completed using a load cell and the mean lift force at the maximum power output was measured to be 23.8 mN.