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On the design and implementation of decision-theoretic, interactive, and vision-driven mobile robots

University of British Columbia

We present a framework for the design and implementation of visually-guided, interactive, mobile robots. Essential to the framework's robust performance is our behavior-based robot control architecture enhanced with a state of the art decision-theoretic planner that takes into account the temporal characteristics of robot actions and allows us to achieve principled coordination of complex subtasks implemented as robot behaviors/skills. We study two different models of the decision theoretic layer: Multiply Sectioned Markov Decision Processes (MSMDPs) under the assumption that the world state is fully observable by the agent, and Partially Observable Markov Decision Processes (POMDPs) that remove the latter assumption and allow us to model the uncertainty in sensor measurements. The MSMDP model utilizes a divide-and-conquer approach for solving problems with millions of states using concurrent actions. For solving large POMDPs, we present heuristics that improve the computational efficiency of the point-based value iteration algorithm while tackling the problem of multi-step actions using Dynamic Bayesian Networks. In addition, we describe a state-of-the-art simultaneous localization and mapping algorithm for robots equipped with stereo vision. We first present the Monte-Carlo algorithm sigmaMCL for robot localization in 3D using natural landmarks identified by their appearance in images. Secondly, we extend sigmaMCL and develop the sigmaSLAM algorithm for solving the simultaneous localization and mapping problem for visually-guided, mobile robots. We demonstrate our real-time algorithm mapping large, indoor environments in the presence of large changes in illumination, image blurring and dynamic objects. Finally, we demonstrate empirically the applicability of our framework for developing interactive, mobile robots capable of completing complex tasks with the aid of a human companion. We present an award winning robot waiter for serving hors d'oeuvres at receptions and a robot for delivering verbal messages among inhabitants of an office-like environment.

Thesis/Dissertation

application/pdf

2007-12-26

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/245

Computer Science

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/