Optimal switching between geocentric and egocentric strategies in navigation.

O Peleg,L Mahadevan

doi:10.1098/rsos.160128

Abstract

Animals use a combination of egocentric navigation driven by the internal integration of environmental cues, interspersed with geocentric course correction and reorientation. These processes are accompanied by uncertainty in sensory acquisition of information, planning and execution. Inspired by observations of dung beetle navigational strategies that show switching between geocentric and egocentric strategies, we consider the question of optimal reorientation rates for the navigation of an agent moving along a preferred direction in the presence of multiple sources of noise. We address this using a model that takes the form of a correlated random walk at short time scales that is punctuated by reorientation events leading to a biased random walks at long time scales. This allows us to identify optimal alternation schemes and characterize their robustness in the context of noisy sensory acquisition as well as performance errors linked with variations in environmental conditions and agent–environment interactions.

Highlights

Navigation in complex uncertain environments requires information about environmental cues along with the ability to memorize and execute intended plans based on these cues
We introduce a model for the movement of the beetle, or a navigational agent, that is associated with paths that are a characteristic of correlated diffusion on short time scales, and biased diffusion on long time scales [12]
Inspired by the behavioural strategy of navigational movement of the dung beetle, we have posed and solved an optimization problem of geocentric navigation interspersed by egocentric cue integration

Summary

Introduction

Navigation in complex uncertain environments requires information about environmental cues (landmarks) along with the ability to memorize and execute intended plans based on these cues. Not stopping at all avoids the loss of time associated with reorientation, but leads to trajectories that deviate significantly from the intended bearing This leads to a natural question of the optimal rate of switching between the egocentric strategy and the geocentric one. We introduce a model for the movement of the beetle, or a navigational agent, that is associated with paths that are a characteristic of correlated diffusion on short time scales, and biased diffusion on long time scales [12] This allows us to pose and solve an optimization problem for the most efficient switching strategy and characterize its robustness in the presence of noisy sensory acquisition and in rough environments, with relevance to questions that go beyond the original motivation for the problem

Mathematical model

Regular reorientation

Dynamic reorientation

Discussion