PhD thesis available

Guang Li guang at ce.chalmers.se
Fri Nov 19 10:37:46 EST 1999


Dear researchers,

A PhD thesis is available at

Department of Computer Engineering
Chalmers University of Technology
S-412 96 Gothenburg, Sweden

Anyone interested please reply this mail to request a copy of it.

Regards

Guang Li


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Title: Towards On-line Learning Agents for Autonomous Navigation


Abstract

The design of a mechatronic agent capable of navigating autonomously
in a changing and perhaps previously unfamiliar environment is a very
challenging issue.

This thesis addresses this issue from both functional and system
perspectives. Functions such as spatial representation, localization,
path-finding and collision avoidance are essential to autonomous agent
navigation. Four types of learning related to these functions have
been identified as important: sensory information categorization and
classification, the learning of stimulus-response mapping, the
learning of spatial representation and the coding and adaptation of
the travel experience with regard to specific tasks. It is argued
that, in order to achieve a high degree of autonomy at the system
level, it is essential to implement each of these navigational
functions with a highly autonomous learning technique. An analysis of
several representative artificial neural network (ANN) algorithms for
their degrees of autonomy and computational characteristics indicates
that none of the learning techniques analyzed is alone sufficient in
terms of spatial learning.

It is shown that biology can be inspirational in finding a possibly
better, or perhaps more complete, solution to the learning of spatial
representation than previous engineering or ANN based approaches. In
particular, data on the biological head direction system have inspired
the generation of a computational model which is shown to be able to
use learned environmental features to correct the directional error
accumulated by dead-reckoning in a simulated mobile
robot. Furthermore, using a hippocampal place learning system in
biological systems as an inspiration, a network model of dynamic cell
structure is suggested. It allows an autonomous agent to perform tasks
such as environmental mapping, localization and path-finding. In this
model, a focus mechanism is included to help minimize computation
needs by directing the adaptation of the network and the path-finding.

The thesis also discusses various approaches toward achieving a high
degree of autonomy at the system level. It is also shown that a feed
forward gating mechanism can be combined into a layered design
framework to accommodate the interaction between various navigational
functions having high degrees of autonomy.




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