Although many researchers have invested time into improving the capabilities of flapping wing drones, their low endurance time still limits the applications they can be effectively used for. If the power consumed for flight of these systems could be reduced, their flight times could be improved, increasing the range of applications for which they could be effective. In this study, a nonlinear vibratory-based spring actuation mechanism is proposed for a flapping wing nano air vehicle (FWNAV) in order to investigate its power consumption compared to classical systems. The FWNAV considered in this work is composed of a slider crank actuation mechanism with a bumblebee inspired wing shape. A single degree of freedom lumped-parameter model with a nonlinear spring force, total mass, forcing, transmission ratio, and linear damping factor is used for the dynamical modeling of the system. This simplified model of the system allows analytical expressions to be easily derived for the system so that a parametric study can be carried out to understand the influence of different parameters on the FWNAV’s performance to determine ideal configurations to limit input power to increase flight times. A classical actuation system, modeled as a single degree of freedom lumped-parameter model without a spring, is considered to compare against to understand the impact of including a spring, either linear or nonlinear, on the FWNAV’s power consumption.

By including a spring in the actuation system, the resonance phenomenon can be exploited to decrease the forcing input into the system or to reduce the required input frequency to achieve lift necessary for hovering. By minimizing either the input forcing or necessary frequency, the input power will be decreased compared to a classical system without a spring. Although input power can be decreased, the tradeoff is the necessity for higher actuator displacements which requires additional design considerations. Preliminary results show that the transmission ratio has a large effect on the performance of the system due to its impact on the quadratic damping coefficient (drag force) and too large of transmission ratios result in an overdamped system. The resonance phenomenon greatly reduces the necessary forcing required for hovering of the system at the expense of necessary actuator displacement. Additionally, including a nonlinear spring can have a positive influence on power input by taking advantage of softening effects which further reduce the necessary frequency into the system, directly reducing the needed power. Flapping-wing designers can inspire from this design process and proposed system to move further in the development of efficient bio-inspired systems.

 


Dynamics and Performance of a Vibratory-Based Actuation Mechanism for Hovering Air Vehicles

Division / Sponsors: 
Design Engineering Division and Computers & Information In Engineering Division


Paper Proceedings: https://asmedigitalcollection.asme.org/IDETC-CIE/IDETC-CIE2020/volume/83907

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