Integration of scheduling and control in holonic manufacturing systems

status: publishe

Schedule Execution using Perturbation Analysis

In a holonic shop floor control (SFC) architecture, a reactive scheduler co-operates with an autonomous on-line SFC system to combine high performance with reactivity against disturbances. To take its decisions, the on-line SFC system uses the existing schedule as advice. This "schedule execution" problem (SE) is not trivial, because the decisions taken by the on-line 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 non-linearities in the production system by a combination of linearisation and feedback control. 1. Introduction In industry, high performance schedulers currently are hardly used, due to the lack of schedule robustness [14]. While a near-optimal schedule is executed on the shop floor, several disturbances occur: rush orders, machine breakdowns, etc. It turns out that the performance of a schedule is very sensible to these..

Design pattern for integrating centralised scheduling in distributed holonic manufacturing systems

status: publishe

Generic concepts for holonic manufacturing control

status: publishe

Interaction mechanisms in holonic manufacturing systems

status: publishe

Schedule Execution In Holonic Manufacturing Systems

: To bridge the gap between advanced scheduling research and industrial practice, high performance scheduling needs to be combined with reactivity to disturbances. This paper presents an architecture for shop floor control (SFC) that builds upon the concepts of holonic manufacturing and combines the advantages of traditional hierarchical control with the benefits of distributed control. The architecture supports the use of several control strategies, like hierarchical control, heterarchical control and other holonic control strategies. These intermediate strategies are based on a tight co-operation between scheduler and SFC holon. Keywords: Holonic manufacturing, shop floor control, holonic architecture, reactive scheduling 1. INTRODUCTION It is widely understood that there exists a wide gap between research and industrial practice in scheduling and shop floor control (SFC) (Parunak, 1991). During several years, the calculation of near-optimal schedules, preferably on-line, has bee..

Schedule Execution For A Holonic Shop Floor Control System

: The control structure of a traditional shop floor control system (SFCS) is built according to a strict multi-level hierarchy. Such a SFCS is very rigid and does not support evolution nor adaptation to the factory needs. Holonic manufacturing is a new approach to deal with these problems. A holonic manufacturing system is a highly decentralised system consisting of co-operative, intelligent, autonomous modules, called 'holons', that together yield an agile and self-organising manufacturing system and support global optimisation. This paper presents a holonic architecture for a SFCS. The architecture supports the use of several control strategies, like hierarchical control, heterarchical control and other holonic control strategies. These intermediate strategies are based on a tight cooperation between scheduler and SFC holon. It is shown that a Gantt chart does not contain sufficient information to execute a schedule while being subject to disturbances. Using partial derivatives of th..

Predictability of hierarchical, heterarchical and holonic control

status: publishe

Holonic manufacturing systems: - architectural and manufacturing control issues

Afdeling Productietechnieken, machinebouw en automatisering (PMA)status: publishe