Real-time temporal and causal reasoning for intelligent control

ABSTRACT

Automation of the control of complex systems has been achieved through the application of computers using such tools as closed-loop control, finite-state machines, etc. However, a number of tasks in the control of such processes must still be performed by human operators, resisting conventional automation efforts. These tasks usually involve unforeseen circumstances, such as defective controller hardware or unusual behavior of the application being controlled. Operators often use experience or heuristic reasoning to cope with these types of process deviations. In this paper, we will describe the theory and design of a generic temporal/causal system called TEMPROS (TEMporal PROgramming System) used to perform intelligent real-time control, capable of assuming many of the responsibilities that are currently exclusively performed by human operators. The system uses temporal propositions as its reasoning mechanism, deviating from current temporal reasoning systems by adding the new state “potentially true” to the truth value of a proposition. In addition, the system employs a plan hierarchy and a “lazy instantiation” mechanism to achieve the performance needed to make intelligent decisions in real time. We shall also outline the application of TEMPROS to the domain of growing gallium arsenide crystals using the LEC process.

REFERENCES

• Allen: Allen, J.F., Maintaining Knowledge about Temporal Intervals, Readings in Knowledge Representation, Edited by R.J. Brachman and H.J. Levesque, Morgan Kaufman Publishers, 1985
• Kahn and Gorry: Kahn, K., Gorry, G.A., Mechanizing Temporal Knowledge, Artificial Intelligence 2 (1971), 189-208
• McDermott: McDermott, D., A Temporal Logic for Reasoning About Processes and Plans, Cognitive Science 6, 101-155 (1982)
• Shoham: Shoham, Y., Reasoning about Causation in Knowledge Based Systems, 2nd Conference on Ai Applications, 1985

INDEX TERMS

Primary Classification:
  I. Computing Methodologies
  I.2 ARTIFICIAL INTELLIGENCE
      I.2.1 Applications and Expert Systems
          Subjects: Industrial automation

Additional Classification:
  J. Computer Applications
  J.7 COMPUTERS IN OTHER SYSTEMS
      Subjects: Command and control

  K. Computing Milieux
  K.6 MANAGEMENT OF COMPUTING AND INFORMATION SYSTEMS
      K.6.1 Project and People Management
          Subjects: Systems development

General Terms:
Design, Human Factors, Management, Theory