Comparison of synchronous and asynchronous actuation strategies in response to perturbations

There are two regimes for actuating flapping wings known as synchronous and asynchronous. Synchronous flapping is where each wing beat corresponds to a muscle contraction caused by a neural signal resulting in the wing beat frequency matching the neural excitation frequency. In contrast, the asynchronous regime’s wing beat frequency is decoupled from the neural activation due to its muscle properties (delay stretch activation). The wing beat frequency from this regime is an emergent property of the system and so is affected by the interactions between the body, actuators and external fluid. We are interested in how these two different actuation strategies perform in different scenarios for example how they respond to perturbations.

Dynamics in fluids can be difficult to model hence we want to use a scaled robotic platform to help capture real world effects of air on the wing. Our collaborators in UCSD, the Gravish Lab have developed a robotic flapping wing which captures important features of the biological system such that we can simulate the two actuation strategies. In our wind tunnel which is suitable for creating laminar, low speed airflow, we are investigating how the robot responds to perturbations at various wind speeds for a set wingbeat frequency (synchronous) and an emergent wingbeat frequency (asynchronous). As the behaviour of the asynchronous regime depends on external factors such as the fluid, the regime may be able to adapt to oncoming airflow to enable faster recovery or resistance to perturbations.
This study helps us understand more about the aerodynamics and emergent kinematics on centimeter scale insect flight as well as aid in the development of small scaled flapping robots.