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|Title: ||Visual homing in field crickets and desert ants: a comparative behavioural and modelling study|
|Authors: ||Mangan, Michael|
|Supervisor(s): ||Webb, Barbara|
|Issue Date: ||24-Nov-2011|
|Publisher: ||The University of Edinburgh|
|Abstract: ||Visually guided navigation represents a long standing goal in robotics. Insights may
be drawn from various insect species for which visual information has been shown
sufficient for navigation in complex environments, however the generality of visual
homing abilities across insect species remains unclear. Furthermore variousmodels
have been proposed as strategies employed by navigating insects yet comparative
studies across models and species are lacking. This work addresses these questions
in two insect species not previously studied: the field cricket Gryllus bimaculatus
for which almost no navigational data is available; and the European desert ant
Cataglyphis velox, a relation of the African desert ant Cataglyphis bicolor which has
become a model species for insect navigation studies.
The ability of crickets to return to a hidden target using surrounding visual cues
was tested using an analogue of the Morris water-maze, a standard paradigm for
spatial memory testing in rodents. Crickets learned to re-locate the hidden target
using the provided visual cues, with the best performance recorded when a natural
image was provided as stimulus rather than clearly identifiable landmarks.
The role of vision in navigation was also observed for desert ants within their
natural habitat. Foraging ants formed individual, idiosyncratic, visually guided routes
through their cluttered surroundings as has been reported in other ant species inhabiting
similar environments. In the absence of other cues ants recalled their route
even when displaced along their path indicating that ants recall previously visited
places rather than a sequence of manoeuvres.
Image databases were collected within the environments experienced by the insects
using custompanoramic cameras that approximated the insect eye viewof the
world. Six biologically plausible visual homing models were implemented and their
performance assessed across experimental conditions.
The models were first assessed on their ability to replicate the relative performance
across the various visual surrounds in which crickets were tested. That is,
best performance was sought with the natural scene, followed by blank walls and
then the distinct landmarks. Only two models were able to reproduce the pattern
of results observed in crickets: pixel-wise image difference with RunDown and the
centre of mass average landmark vector.
The efficacy of models was then assessed across locations in the ant habitat.
A 3D world was generated from the captured images providing noise free and high
spatial resolution images asmodel input. Best performancewas found for optic flow and image difference based models. However in many locations the centre of mass
average landmark vector failed to provide reliable guidance. This work shows that
two previously unstudied insect species can navigate using surrounding visual cues
alone. Moreover six biologically plausible models of visual navigation were assessed
in the same environments as the insects and only an image difference based model
succeeded in all experimental conditions.|
|Sponsor(s): ||Medical Research Council (MRC)|
|Appears in Collections:||Informatics thesis and dissertation collection|
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