Julien Provost

An event-driven manufacturing information system architecture for Industry 4.0

Future manufacturing systems need to be more flexible, to embrace tougher and constantly changing market demands. They need to make better use of plant data, ideally utilising all data from the entire plant. Low-level data should be refined to real-time information for decision-making, to facilitate competitiveness through informed and timely decisions. The Line Information System Architecture (LISA), is presented in this paper. It is an event-driven architecture featuring loose coupling, a prototype-oriented information model and formalised transformation services. LISA is designed to enable flexible factory integration and data utilisation. The focus of LISA is on integration of devices and services on all levels, simplifying hardware changes and integration of new smart services as well as supporting continuous improvements on information visualisation and control. The architecture has been evaluated on both real industrial data and industrial demonstrators and it is also being installed at a large automotive company. This article is an extended and revised version of the paper presented at the 2015 IFAC Symposium on Information Control in Manufacturing (INCOM 2015). The paper has been restructured in regards to the order and title of the chapters, and additional information about the integration between devices and services aspects have been added. The introduction and the general structure of the paper now better highlight the contributions of the paper and the uniqueness of the framework.

Generation of Single Input Change Test Sequences for Conformance Test of Programmable Logic Controllers

Conformance test is a functional test technique which is aiming to check whether an implementation, seen as a black-box with inputs/outputs, conforms to its specification. Numerous theoretical worthwhile results have been obtained in the domain of conformance test of finite state machines. The optimization criterion, which is usually selected to build the test sequence, is the minimum-length criterion. Based on experimental results, this paper focuses on the generation of a single input change (SIC) test sequence from a specification model represented as a Mealy machine; such a sequence is aiming at preventing from erroneous test verdicts due to incorrect detection of synchronous input changes by the programmable logic controller (PLC) under test. A method based on symbolic calculus to obtain the part of the specification that can be tested with a SIC sequence is first presented. Then, an algorithm to build the SIC test sequence is detailed; three solutions are proposed, according to the connectivity properties of the SIC-testable part.

A formal semantics for Grafcet specifications

This paper shows how the behavior of a model described in the specification language proposed by the IEC 60848 standard can be represented, without semantics loss, in a formal manner, by a finite state machine (FSM) with logic inputs and outputs. This contribution is illustrated on a nontrivial example; this case study points out that the duration of the construction of the equivalent FSM complies with the requirements of designers of automation systems.

Testing programmable logic controllers from finite state machines specification

This paper shows, on the basis of experiments, that execution of conformance tests of programmable logic controllers with minimum-length test sequences built from specifications in FSMs may yield spurious results. A new approach to build test sequences is then proposed to remove, or at least strongly lessen, this issue.

Test sequence construction from SFC specification

This paper focuses on conformance test of electronic programmable devices whose specification is given in Sequential Function Chart (SFC). More precisely, a method is proposed to obtain automatically, from this specification, one minimum length test sequence which permits the exhaustive test of the behavior of the device. This method takes advantage of previous results on construction of the state machine representation of a SFC and on test of Mealy machines; conversely, it extends the industrial use possibilities of this latter technique. The contribution is exemplified on a simple model.

SIC-testability of sequential logic controllers

SIC (Single Input Change) test sequences must be privileged for conformance test of logic controllers, to prevent from erroneous test results when the test-bench and the implementation under test are not synchronized. This paper proposes first a definition of the SIC-testable part of a sequential specification model, i.e. the part of the model that can be tested by using a sequence starting from the initial state and for which only one input can change at one at the same time. Then, an algorithm to determine the SIC-testable part is given; if this part is the whole specification, the specification model is declared totally SIC-testable. Once the SIC-testable part obtained, a SIC sequence for conformance test of an implementation of this part can be generated. These contributions are exemplified on an example.

Design-to-test approach for black-box testing of programmable controllers

This paper focuses on a global consideration of design and testing phases of a safety-critical automation system with programmable controllers. A design-to-test approach is proposed to improve the testability of programmable controllers and reduce overhead during the testing phase, under the premise that the nominal behavior of a system is guaranteed to remain unchanged during normal execution. This approach is elaborated and illustrated on a medium scale case study throughout the paper, and then applied to a larger case study in order to illustrate its scalability.

Multi-view hand tracking using epipolar geometry-based consistent labeling for an industrial application

This paper addresses a visual tracking and analysis method for automatic monitoring of an industrial manual assembly process, where each worker sequentially picks up components from different boxes during an assembling process. Automatic surveillance of assembling process would enable to reduce assembling errors by giving early warning. We propose a hand tracking and trajectory analysis method from videos captured by several uncalibrated cameras with overlapping views. The proposed method consists of three modules through single-view hand tracking, consistent labeling across views, and optimal decision from multi-view temporal dynamics. The main novelties of the paper include: (a) target model learning with multiple instances through K-means clustering applied to accommodate different levels of light reflection; (b) optimal criterion for consistent labeling of tracked hands across views, based on the symmetric epipolar distance; (c) backward correction of mis-detection by combining epipolar lines with previously tracked results; (d) a multi-view voting scheme for analyzing hand trajectory using binary hand location maps. Experiments have been conducted on videos by multiple uncalibrated cameras, where a person performs assembly operations. Test results and performance evaluation have shown the effectiveness of this method, in terms of multi-view consistent estimation of hand trajectories and accurate interpretation of component assembly actions.

Online Support for Shop-Floor Operators Using Body Movements Tracking

This paper presents results of experiments on the integration of human operators and automation in the context of assembly systems. Several experiments have been conducted to evaluate the use of augmented reality applications in order to provide dynamic work instructions and online feedback information to a shop-floor operator. Based on these results, an experimental platform has been developed so that the shop-floor operator and the automated system behave as a closed-loop system.

Planning in assembly systems — A common modeling for products and resources

This paper presents a method for modeling robot and human resources in the context of assembly systems planning. In assembly systems, several redundant resources can be used to increase system flexibility. However, the “quality” of a sequence planning strongly depends on the “quality” of the system modeling. Furthermore, occurrence of unexpected events or variations in availability of resources may have significant impact on the actual planning. Instead of using simplistic models such as available or unavailable resources, the method presented in this paper proposes a more detailed modeling of resource abilities. Products and resources are considered on the same levels and matched together on a final step. The aim of this modeling is to permit analyses and to increase system flexibility.