Schedule execution using perturbation analysis

Abstract

In a holonic shop floor control (SFC) architecture, a reactive scheduler co-operates with an autonomous online SFC system to combine high performance with reactivity against disturbances. To take its decisions, the online SFC system uses the existing schedule as advice. This "schedule execution" (SE) problem is not trivial, because the decisions taken by the online SFC system are local decisions in a combinatorial optimisation problem. By representing the schedule as a graph, this paper presents an algorithm for SE, based on perturbation analysis. It tackles the nonlinearities in the production system by a combination of linearisation and feedback control.