Real-time temporal and causal reasoning for intelligent control

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.