Meeting Abstract
In the absence of much passive stability, flying insects rely upon active stabilisation, necessitating the provision of rich sensory feedback across a range of modalities. Mechanosensors that respond to aerodynamic flows are ubiquitous on the bodies of flying insects; in our model species, the desert locust (Schistocerca gregaria), approximately 430 flow-sensitive hairs (trichoid sensilla) on the front of the head provide a highly directional response to the oncoming flow. The directional sensitivity of these hairs may allow them to sense changes in angle of attack and sideslip, and are thus potentially important in both lateral and longitudinal flight stability. Here we characterize how the flow over each hair field varies with angle of attack and sideslip. We use computational fluid dynamics to model how the flow around the head varies with head orientation, validating our simulations against wind tunnel particle image velocimetry on a scale model. The simulations reveal that some fields of hairs are better placed to measure angle of attack, while others are better placed to sense changing sideslip. In addition we find that some hair fields could provide consistent sensing over a range of angles, whereas other fields appear to have a threshold response, with greatly reduced sensing of oncoming flow over certain head angles. We go on to compare the measured local flow directions with the directional sensitivity of each of the sensilla, measured morphologically using microCT scans. These data provide information on the curvature of each hair, which corresponds to the peak directional sensitivity of the hair to airflow. The relationships between these data allow us to identify what features of the flow certain groups of hairs might be measuring, and how this information could be used in flight control.
