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Insects are well known to be adept at flying through cluttered natural environments. This ability
to avoid collisions and control flight speed is an active field of interest for potential applications
in unmanned aerial vehicles. Previous studies have shown that insects primarily rely on visual
motion of the environment, known as optic flow, to perform flight manoeuvres such as course
control, landing, terrain following, etc. Vision based flight behaviours of honeybees have been
studied extensively in the past and have been explained in terms of either the optomotor response
or the collision avoidance (centering) response. However, the strategies used for avoiding smaller
objects in the frontal view field remain unclear. This study investigates the strategies being used
by honeybees (Apis Milfera) to avoid such obstacles. This was done by performing behavioural
experiments, where the bees were trained to fly in a tunnel and were then presented with cylindrical
obstacles of six different sizes ranging from 25mm to 165mm. The flights were recorded
using a GoPro camera and then digitised using Matlab. The digitised trajectories have then
been analysed for cues such as retinal angle, relative retinal expansion velocity(RREV), optic
flow, etc., to gain an insight into the visuo-motor strategies being implemented by honeybees to
avoid these obstacles. Our findings, based on analysing major events during flight, such as the
point of deceleration before the obstacle, the point of maximum curvature and the point where
bees cross the obstacle, suggest a combination of RREV and optic flow based response to avoid
these obstacles.
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