We are implementing a control system for a discrete manufacturing environment that partitions tasks using a negotiation protocol like the contract net described by Smith and Davis [24,25,26,3]. The application domain differs in interesting ways from those to which contract nets have previously been applied. This report

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Anytime algorithms are useful when the time available for computation is limited, that is, when there is a tradeoff between the time cost of further computation and the cost of using a solution that is only partially complete. Although machine planning presents this sort of problem, there has not yet been a treatment of anytime planning for the general case, that is, a treatment not tied to specific domains. In this paper, we present a model for general-purpose anytime planning which allows the user to trade off the optimality of plans generated deliberatively with the speed of reactive plan generation. The anytime planner allows an interruption of hierarchical deliberative planning at the completion of any criticality level, and completes the plan at execution time using reactive planning. We illustrate the usefulness of this approach on a manufacturing domain. Introduction Automation of planning techniques can potentially save a great deal of design and programmin...

Simulation serves as an effective decision support tool in flexible manufacturing systems for understanding and analyzing the effect of changes to the system environment. Due to the variety of situations that have to be evaluated, a generative scheduler for such a system must be more flexible than its realistic equal while still producing detailed and accurate schedules. This research presents a possible solution to this problem and is intended for use in a distributed, reactive, virtual environment. The solution exploits the advantages gained by using multiple processes in a distributed environment to create, simulate, and evaluate possible schedules. The system is designed on the premise that a distributed parallel search and simulation of competing schedules with accompanying heuristics and subgoaling will greatly reduce the search space and control the state space explosion. The architecture implemented in this research exhibits a paradigm shift by focusing on scheduling over a dis...

A new algorithm for the distributed simulation and evaluation of on-line schedules is presented. Generally, on-line scheduling has often been restricted to scheduling activities on a single machine or workcell. The exploratory research reported in this paper expands on-line scheduling to encompass several machines or workcells. Branch and bound search techniques are used in the simulation to reduce the number of simulations simultaneously in execution. The algorithm is applied for the distributed simulation of on-line schedules for a manufacturing example. 1. INTRODUCTION Several obstacles prevent current assembly and manufacturing lines from capitalizing on the promises of complete automation. Among these are the difficulties in scheduling 1 resources and ordering processes such that optimal use is made of the current configuration. Fox and Kempf [FoKe85] distinguish the differences between planning and scheduling and suggest that a distinction is both essential and beneficial. Wh...

Simulation serves as an effective decision support tool in flexible manufacturing systems for understanding and analyzing the effect of changes to the system environment. Due to the variety of situations that have to be evaluated, a generative scheduler for such a system must be more flexible than its realistic equal while still producing detailed and accurate schedules. This research presents a possible solution to this problem and is intended for use in a distributed, reactive, virtual environment. The solution exploits the advantages gained by using multiple processes in a distributed environment to create, simulate, and evaluate possible schedules. The system is designed on the premise that a distributed parallel search and simulation of competing schedules with accompanying heuristics and subgoaling will greatly reduce the search space and control the state space explosion. The architecture implemented in this research exhibits a paradigm shift by focusing on scheduling ...

Abstract not found

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2.1. Modeling assemblies 2

A scheme for domain and task representation in an interactive learning environment is described. The approach, based on recent enhancements to a classic AI planning formulation, enables suitable feedback to be incorporated economically into tutors for a range of procedural domains. The method is applied to the problem of simulating the operation of a video cassette recorder and representing tasks within this domain.