Optimization of the Kinematics of a Flapping Wing MAV in Hover for Enhanced Performance

Abstract

The kinematics of a rigid and flexible flapping wing micro air vehicle (MAV) in hover are optimized for enhanced performance using surrogate based approximation of the unsteady aerodynamic loads. The surrogates are generated using kriging interpolation of the time averaged thrust generated and power consumed by the wings. The fitting data is obtained using a nonlinear approximate aeroelastic model that combines a nonlinear finite element based structural dynamic model with an approximate unsteady aerodynamic model. The parameter space for the rigid wings consists of seven kinematic parameters. For the flexible wing case, six structural parameters are used to augment the kinematic parameters, resulting in a total of 13 design variables. The surrogates are combined with a hybrid search algorithm to identify feasible designs that produce the desired combination of thrust and power. The best rigid and flexible configurations predicted using the surrogates are superior to the best designs available in the corresponding sets of sample points used to create the surrogates. Thrust and power are found to be competing design objectives. The phase angle between flap and pitch motions has a significant impact on the wing performance for fixed stroke amplitudes and frequency. The peak performance of flexible wings occurs for smaller amounts of pitch actuation compared to the rigid wings due to elastic wing twist. Rigid wings performed better than flexible wings in several regions of the parameter space, leading to the conclusion that the choice between rigid or flexible wings is not straightforward.

Multidisciplinary design optimization of the flapping wing system for forward flight

“…Recently, some optimization studies consider the deformation of the wing structure to evaluate the aerodynamic performance. 8,9 However, optimization researches on flapping kinematics and the wing structure are rare for a practical flapping wing design. The research results from biologists and physicists indicate that the flexibility of the flapping wing has unnegligible effects on its performance, such as the thrust and propulsive efficiency.…”