Automate programmable industriel

vignette|Deux automates programmables industriels & leurs périphériques, montés en volant, pour test et analyse. Un automate programmable industriel, ou API (en anglais programmable logic controller, PLC), est un dispositif électronique numérique programmable destiné à la commande de processus industriels par un traitement séquentiel. Il envoie des ordres vers les préactionneurs (partie opérative ou PO côté actionneur) à partir de données d’entrées (capteurs) (partie commande ou PC côté capteur), de consignes et d’un programme informatique. Lorsqu'un automate programmable remplit une fonction de sécurité, il est alors appelé automate programmable de sécurité ou APS. Présentation vignette|Automate de Allen-Bradley installé dans une armoire. vignette|Automate dans une armoire électrique. On nomme automate programmable industriel (API) un type particulier d'ordinateur, robuste et réactif, ayant des entrées et des sorties physiques, utilisé pour automatiser des processus comm

Applying model checking to industrial-sized PLC programs

Simon Bliudze, Borja Fernandez Adiego, Jean-Charles Tournier

Programmable Logic Controllers (PLCs) are embedded computers widely used in industrial control systems. Ensuring that a PLC software complies with its specification is a challenging task. Formal verification has become a recommended practice to ensure the correctness of safety-critical software but is still underused in industry due to the complexity of building and managing formal models of real applications. In this paper, we propose a general methodology to perform automated model checking of complex properties expressed in temporal logics (e.g., CTL, LTL) on PLC programs. This methodology is based on an Intermediate Model (IM), meant to transform PLC programs written in various standard languages (ST, SFC, etc.) to different modeling languages of verification tools. We present the syntax and semantics of the IM and the transformation rules of the ST and SFC languages to the nuXmv model checker passing through the intermediate model. Finally, two real cases studies of CERN PLC programs, written mainly in the ST language, are presented to illustrate and validate the proposed approach.

Institute of Electrical and Electronics Engineers2015

Model-based automated testing of critical PLC programs

Simon Bliudze, Jean-Charles Tournier

Testing of critical PLC (Programmable Logic Controller) programs remains a challenging task for control system engineers as it can rarely be automated. This paper proposes a model-based approach which uses the BIP (Behavior, Interactions and Priorities) framework to perform automated testing of PLC programs developed with the UNICOS (UNified Industrial COntrol System) framework. This paper defines the translation procedure and rules from UNICOS to BIP which can be fully automated in order to hide the complexity of the underlying model from the control engineers. The approach is illustrated and validated through the study of a water treatment process.

IEEE2013

Haptic interface design and control with application to surgery simulation

Ulrich Spälter

This thesis proposes a framework for haptic devices interacting with virtual environments. As application of the theoretical results a haptic device for the surgical training of hysteroscopy, a gynecologic intervention, is presented. Surgery simulators, which can be described as 'flight simulators for surgeons', comprise a virtual reality for modeling and visualization of organs, and the haptic device: While the surgeon interactively follows the scene on the computer screen, he perceives the contact forces at the tool handle of the surgical instrument. The haptic device tracks the position of the surgery tool and transforms the virtual contact forces to real forces, which can be actually felt by the surgeon. This thesis treats haptic devices with application to surgery simulators for minimally-invasive surgery. Haptic interfaces are complex mechatronic systems and show inherent trade-offs between haptic realism and system stability. Human factors play an important role, as the human operator can both stabilize or destabilize the system. The haptic perception, which can vary between individuals, as a criterion for haptic rendering quality is still not formalized. The optimization of haptic interfaces, within focus of research since 15 years ago, has remained a complex task. However, with look at the emerging applications for haptics, it has become an even more important topic. For this reason it is necessary to integrate mechanical design, control design, mechatronic elements and human factors in a unifying approach. This thesis highlights the principal trade-offs of haptic interfaces and works out design guidelines for new developments and quantitative information on where and how to optimize haptic systems. As application example a haptic interface for the simulation of hysteroscopy, a gynecologic intervention on the female uterus, has been realized as prototype. The device takes the characteristics of hysteroscopy into account and introduces features like insertion and complete removal of the surgery tool from the haptic interface. A design methodology is proposed, which combines aspects of theoretical kinematics based on Lie-Groups with integrated product development – a systematic approach for engineering tasks. The result, a novel kinematic design, has been realized as haptic interface prototype. The well-known affine parameterization for all stabilizing controllers is shown to be a well-suited tool for haptic control synthesis. It provides insights into the control trade-offs and allows to integrate human factors at controller design stage. The resulting controller, demonstrated by experimental results, can reduce parasitic effects (friction, device dynamics) close to and below the human perception threshhold, thus making the device transparent within the specified bandwidth and suitable for real-time implementation. For numerical controller representation the δ-operator is discussed. It unifies continuous and discrete time domain and has beneficial numerical properties. As there is still no standardized procedure for technical performance evaluation of haptic interfaces methods proposed in literature are summarized. In the near future a large market for haptic technology can be expected with applications from surgery-assist devices and drive-by-wire interfaces in automobiles to entertainment, which highlights the relevance of the treated topic.

EPFL2006

Haptic interface design and control with application to surgery simulation

Ulrich Spälter

EPFL2006