Corina Popescu

Towards the energy efficient future factory

Up to now, most factories and their processes were designed and constructed with the cost as the most important economic factor. However due to the increased changes in energy sector, the energy optimization should be another key indicator for cross layer optimization. In order to achieve this optimization, energy has to be measured locally and almost in real time, while manufacturing control activities should also be aware of the energy consumed. Furthermore higher-residing decision support systems and enterprise services, will take also into consideration the overall energy consumption, for each process and optimize globally and locally. These goals are assisted with the increasing automation within the factories that can provide better visibility and efficiency of the shop floor.

Runtime Modeling of Flow for Dynamic Deadlock-free Scheduling in Service-oriented Factory Automation Systems

Abstract Changes in equipment and production demand cannot be predicted at the design stage. Therefore, decision taking mechanisms must rely on real time information collected from the shop floor. To perform scheduling and routing optimization, not only modifications in values of parameters of interest, but also in the flow itself must be accounted for. This paper addresses this problem and proposes a method to formally model, at runtime, the flow within a service-oriented manufacturing line. The resulting representation assists deadlock free dynamic scheduling of the system.

A Petri net-based approach to incremental modelling of flow and resources in service-oriented manufacturing systems

In order to overcome the myopia problem, routing strategies must be based on formal representations of flow that automatically account for modifications in the values of parameters of interest and in the model itself. This work addresses this problem and discusses how to automatically incorporate resources (e.g. workstations/transportation devices/storage) in a Petri-net-derived model of flow that is modifiable at runtime to reflect and influence the routing in a manufacturing line. The modelling approach takes into consideration scalability needs and was experimentally validated. The applicability of the models is shown for PN-based dynamic scheduling.

Verification of the Consistency of Timing Constraints of the Orchestration of Factory Automation Web Services

This paper presents a methodology to verify the timing constraints of the orchestrator of factory automation web services. The formalism that was chosen to represent the sequencing of the services as well as their timing behavior is Timed Net /Condition Event Systems (TNCES), due to both its modular nature and its ability to express concurrent behaviors and non-determinism. A description of the means of calculating the relationship between the timing constraints of the control constructs used to specify the orchestration and respectively the intermediate constraints of the composing services is given. A small theoretical example is provided.

On ontology mapping in factory automation domain

This paper is intended to provide a start point towards developing accurate mathematical means of achieving inter-vendor interoperability in factory automation domain. The proposed approach assumes a description of the physical laws of the basic operations performed by the devices is incorporated into the OWL-S classes at operation ontology level. This way a part of the translation process may be reduced to analysis of the compatibility of linear systems of equations obtained for blocks of operations polled from the analyzed ontologies. One-to-one, one-to-many (many-to-one) and many-to-many mapping cases are analyzed separately and details on the theoretical grounds of the translation procedure are given. A research roadmap is presented.

Modeling logical and temporal conditions to formally validate factory automation web services

This paper is focused on presenting the means of modeling the conditions that are tested with either conditional or looping control constructs (repeat-while, repeat-until and if-then-else). The depicted ideas are part of a methodology developed to formally verify and validate the orchestration of factory automation web services. The formalism used to represent in a modular manner the sequencing of services is timed net condition/event systems (TNCES). The basic modules capable of modeling Boolean conditions are illustrated and initial ideas on how to represent timing conditions are sketched.

An Algorithm for Siemens STL representation in TNCES

System engineering process supported by the formal methods should improve the quality of the developed product. Here, a single step in formalization of industrial programming is highlighted together with its place in the whole framework for formal validation of industrial systems. This paper describes an algorithm of translating statement list language to the timed net condition/event systems that forms a controller model. Thus controller models can be generated for the industrial automated systems implemented in statement list.

Remote energy monitoring unit design and implementation

This paper presents the design and implementation of a remote energy monitoring unit for production systems. The unit is capable of monitoring and visualizing total energy cost, the energy cost per production operation and the energy consumption associated to the processing of a specific product. Thus the next step for the energy consumption optimization can be performed by knowing consumption of specific operations. The unit is mobile and can be reallocated and integrated with different production systems providing web-service interfaces for remote monitoring. FESTO MPS production line is used in this paper for demonstration purposes. The paper shows how the user can obtain the information on energy consumption and describes a set of KPIs for energy monitoring.

Matrix-based conflict resolution algorithm: Application to path selection in PN-based scheduling search

This paper presents an algorithm that selects a group of independent events out of a given set of possibly conflicting actions. The procedure is matrix-based and was implemented in JAVA to guide backtracking scheduling search based on a Petri Net-derived model of flow. The manufacturing systems particularly addressed in the implementation are using Web Services to implement the Service-Oriented-Architecture pattern. However, the conflict resolution method is applicable to more general settings, provided that conflicts are automatically detectable and expressible in matrix-form.

Modelling interaction-aware services from an orchestration viewpoint

The need to express the flow of services separately from peer to peer interactions has lead to the definition of two concepts: orchestration and choreography. This paper discusses the modeling challenges arising with the need to express situations in which the boundary between the two notions cannot be clearly set, and yet only one of the aspects - specifically the orchestration part - is of interest for representation and analysis.