Accession Number : ADA184337
Title : Management of Temporal Constraints for Factory Scheduling.
Descriptive Note : Technical rept.,
Corporate Author : CARNEGIE-MELLON UNIV PITTSBURGH PA ROBOTICS INST
Personal Author(s) : Le Pape,Claude ; Smith,Stephen F
Report Date : Jun 1987
Pagination or Media Count : 20
Abstract : This paper, presents constraint propagation techniques used in the OPIS scheduling system to update schedule descriptions and detect introduced inconsistencies. This approach is summarized as follows: 1) a hierarchical model is used to represent resources and operations to be performed. Schedules are developed and maintained at different levels of precision which are explicitly associated with resources and operations; constraint propagation is correspondingly performed at different levels, 2) Various scheduling constraints are attached to resources and operations, and combined to derive time bound constraints. A description of the original constraints that collectively impose a bound is explicitly recorded, 3) Time bound constraints are maintained by an object-oriented propagation process: through messages, resources and operations communicate constraints and cooperate to compute time bounds, and 4) When time bounds are inconsistent, their origins provide the information required to construct an appropriate description of the conflicting situation. This description provides OPIS with information needed to make reactive decisions.
Descriptors : *JOB SHOP SCHEDULING , SYSTEMS APPROACH , ROBOTICS , MANAGEMENT PLANNING AND CONTROL , AIR FORCE RESEARCH
Subject Categories : Mfg & Industrial Eng & Control of Product Sys
Distribution Statement : APPROVED FOR PUBLIC RELEASE