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Cognitive Robotics
  

 

Cognitive Robotics

Murray Shanahan, Mark Witkowski and Hisashi Hayashi

Intelligent and Interactive Systems Section

An EPSRC Funded Research Project at the Department of Electrical and Electronic Engineering at Imperial College, University of London


Contents:

This project is now completed. You can read the final report here (ps) or here (pdf). 

Our research in this area continues with the Cognitive Robotics II project.

Aims and Objectives of the Project

The aim of the Cognitive Robotics project has been to design and build software for controlling real (as opposed to merely simulated) robots which (i) are based on the Event Calculus, a well understood and mathematically rigorous formalism for reasoning about action, change, and space (as described in Murray Shanahan's book "Solving the Frame Problem: A Mathematical Investigation of the Common Sense Law of Inertia"), but which (ii) take account of the lessons learned in twenty five years of Robotics practice, in particular the advantages of tight coupling between sensors and actuators, as realised in the behaviour-based architectures of Brooks.

This was a two year research project, completed in August 1999. The project was partly inspired by previous work on the EPSRC funded project "Logic for Commonsense Reasoning about Continuous Change". The term "cognitive robotics" was first introduced by Ray Reiter and his colleagues, who have a research group on this topic at the University of Toronto.

We combine an Abductive Event Calculus based approach with a framework for qualitative spatial reasoning to create a formalism for reasoning about space, shape, action, and continuous change. Using this formalism, theories are constructed which describe the robot's interaction with its world. As shown in Murray Shanahan's AAAI'96 paper, sensor and motor noise can be treated as a form of non-determinism. Given such a theory, sensor data assimilation can be considered as an abductive (reasoning from observable events to valid possible causes) task, for which provably correct algorithms can be constructed.

Our experiments involved a map-building task for a single robot and a logic programming approach to representation and implementation was adopted. The project also developed logic-based control techniques which can exploit abductively constructed maps for planning and navigation. Hisashi Hayashi has been working on logic based techniques for efficient, and correct, methods of replanning. The final stage of the project involved extending these techniques for more than one robot (we have a pair of robots for this purpose). Both robots were controlled as independent processes on a single computer (using Win-Prolog from LPA). Communication between the robots currently used the Windows Dynamic Data Exchange (DDE).

The project used Khepera robots. The Khepera is a small (6cm in diameter, 6cm high), low-cost (~$2,000), relatively easy-to-maintain robotic platform developed at EPFL in Switzerland. It has a minimal suite of eight infra-red proximity sensors, and odometry. It has an on-board 68000 series micro-controller with 256K of RAM. We have developed an extended robot controller program that provides a clean interface between the robot's sensors and motors, and the logic programming used in the project. Several public domain simulators are available for this robot, but wherever possible we prefer to use the actual robots.

At end of the Cognitive Robotics project, we had completed research in the following areas:

  • A formalism for representing and reasoning about action, continuous change, space and shape. The formalism deals with concurrent action, actions with non-deterministic effects, and actions with indirect effects. The formalism takes a qualitative approach to spatial reasoning, reflecting the inherent incompleteness of the robot's knowledge, due to the uncertainty deriving from sensor and motor noise, and due to its limited sensor based perception on the world.
  • Theories expressed in the above formalism characterising the robot's interaction with the world. The world in question is a model "office environment" (scaled to suit the Khepera) containing various obstacles, both fixed and movable. Theories of increasing complexity are required, first to account for movable objects, and then for other robots.
  • Map-building algorithms which are provably correct with respect to an abductive characterisation of sensor data assimilation based on the above theories.
  • Logic programming implementations of these algorithms which supply declarative representations of maps. These implementations were initially tested in simulation, but subsequently mounted and tested on the Khepera robots.
  • A logic programming implementation of an architecture for robot planning and control which has been tested both in simulation and on the real robot. The current "sense-plan-act" architecture is based on a meta-interpreter implemented in Prolog.

The Cognitive Robotics project chaired and hosted Commonsense'98, the fourth Symposium on Logical Formalizations of Commonsense Reasoning.

Look here for Prolog code demonstrating the Abductive Event Calculus Planner.

People on the Project

Murray Shanahan was the principal investigator of this project, Mark Witkowski was employed on the project as a full time research fellow, and Hisashi Hayashi was employed as a full time research associate. For the first year the project was based at the Department of Computer Science at Queen Mary & Westfield College, and employed Rob Miller as research fellow and Fabio Berti as research associate.

Discussion and correspondence about the work on this project is very welcome. Please contact Murray Shanahan, or Mark Witkowski directly.

 

Papers and Publications by the Project Team

Please refer to the Cognitive Robotics II pages for an up-dated list of our publications in the area of Cognitive Robotics.

2000

  • Murray Shanahan, An Abductive Event Calculus Planner, The Journal of Logic Programming, Vol. 44, pages 207-239. [abstract] [compressed postscript].
  • Murray Shanahan and Mark Witkowski, High-Level Robot Control Through Logic, Proceedings ATAL 2000, pages 100-113 (to appear in the Springer-Verlag LNAI series).  [abstract] [compressed postscript] [electronic appendices]
  • Mark Witkowski, The Role of Behavioral Extinction in Animat Action Selection, Proc 6th Int. Conf. on Simulation of Adaptive Behaviour (SAB-00), [abstract] [pdf]
  • Mark Witkowski, Alexander Artikis and Jeremy Pitt, Trust and Cooperation in a Trading Society of Objective-Trust Based Agents, Proc. Autonomous Agents 2000 Workshop on Deception, Fraud and Trust in Agent Societies, pages 127-136 [abstract] [pdf]

1999

1998

  • Hisashi Hayashi, Knowledge Assimilation and Proof Restoration through the Addition of Goals, Proceedings 8th International Conference on Artificial Intelligence: Methodology, Systems, and Applications (AIMSA’98), Lecture Notes in Artificial Intelligence 1480, Springer-Verlag (1998), pages 291–302.
  • A G Cohn, N M Gotts, Z Cui, D A Randell, B Bennet and J M Gooday, Exploiting Temporal Continuity in Qualitative Spatial Calculi, eds M J Egenhofer and R Golledge, Spatial Information Systems, Oxford, 1998.
  • Murray Shanahan, Reinventing Shakey, Working Notes of the 1998 AAAI Fall Symposium on Cognitive Robotics, pages 125–135. [abstract] [compressed postscript]
  • Mark Witkowski, Dynamic Expectancy: An Approach to Behaviour Shaping Using a New Method of Reinforcement Learning, 6th Int. Symp. on Intelligent Robotic Systems (SIRS98), July, 1998, pages 73-81. [abstract] [postscript]

1997

  • Hisashi Hayashi, Language HSimple(R): An Action Language for Representing Concurrent Actions and Continuous Changes, in the Working Notes of the Second Workshop on Practical Reasoning and Rationality, [abstract] [postscript]
  • Murray Shanahan, Solving the Frame Problem: A Mathematical Investigation of the Common Sense Law of Inertia, MIT Press, 1997. [contents]
  • Murray Shanahan, Event Calculus Planning Revisited, in Proceedings of 1997 European Conference on Plannning (ECP 97). An early draft of this paper appears in the Working Notes of the AAAI 97 Workshop on Robots, Softbots, Immobots: Theories of Action, Planning and Control, 1997. [abstract] [compressed postscript]
  • Murray Shanahan, Noise, Non-Determinism and Spatial Uncertainty, Proceedings AAAI 97, pages 153–158 [abstract] [compressed postscript]

1996

  • Rob Miller and Murray Shanahan, Reasoning about Discontinuities in the Event Calculus, in proceedings of the 5th International Conference on Principles of Knowledge Representation and Reasoning (KR 96), 1996. [Abstract] [postscript] [dvi]
  • Murray Shanahan, Noise and the Common Sense Informatic Situation for a Mobile Robot, in the proceedings of AAAI'96, 1996. [Abstract] [compressed postscript]
  • Murray Shanahan, Robotics and the Common Sense Informatic Situation, in the proceedings of ECAI'96, Budapest, Hungary, 1996. [Abstract] [compressed postscript]

Other references, and those before 1996, may be found at the respective author's homepages.

 

Related WWW Sites

This page maintained by Murray Shanahan. Last Change: 14/5/01 (by MW).

 

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