Peak Input Torque Minimization of a Flapping Wing Mechanism for MAVs

Abstract

Flapping wing micro air vehicles (MAVs) are desired for surveillance and reconnaissance in confined spaces, and should exhibit small scale flight with the following abilities: obstacle avoidance, hovering, and slow flight speed. One of the major components of MAVs is the flapping mechanism, which actuates wings to generate sufficient lift and propulsion force. The use of compliant elements in flapping wing MAVs is a possible solution to the decreased power transmission inherently present in the scaling of traditional rigid body mechanisms. To demonstrate the effectiveness of compliant elements, an extension spring and compliant joint were incorporated into the University of Maryland’s Small Bird MAV. The motor torque was derived in terms of the rigid body mechanics, and compliant parameters optimized using an interior point algorithm to minimize the peak motor torque throughout the flapping cycle. Under the assumption of constant aerodynamic load on the wings, the extension spring and compliant joint mechanisms resulted in a 89.25% and a 97.1% reduction in the motor torque from the rigid body mechanism, respectively. To validate this analytical solution, the mechanisms were modeled in MSC Software’s ADAMS simulation engine.