Abstract
Flying insects are capable of achieving remarkable maneuverability with their flapping wings. The wing-driving mechanism in their thorax, called the musculoskeletal system, is flexible unlike conventional drones that normally control their body attitudes with rigid elements. In this study, we investigate the effects of the flexibility in the musculoskeletal system on the kinematics and aerodynamic performance of flapping wings. A dynamic musculoskeletal model (DMSM) consisted of springs, dampers and a mass is developed with a simplified thorax structure of the insect. The DMSM is loosely coupled with a computationally cheap quasi-steady model (CIQSM) and a high-fidelity computational fluid dynamic (CFD) model. The structural properties of DMSM are adjusted through optimization that utilizes the CIQSM and can minimize the power consumption to drive the wing, while generating enough amount of vertical force to support its own weight. The kinematics and the aerodynamic performances with the DMSM are further evaluated by the integrated model coupling the DMSM with the CFD simulator. While the discrepancy between the CIQSM and CFD becomes bigger when the DMSM is more flexible because the error is amplified by the flexible structure, our results reveal that the flexible DMSM can reduce the power consumption to drive the flapping wing noticeably in comparison with the rigid wing-driving mechanism. The results point out the importance of interaction between the flexible wing-driving mechanism and flapping wing aerodynamics for the design of the micro air vehicles as well as the insects.
