Pascale Marangé

Remote Control of Automation Systems for DES Courses

The objective of technical courses is the transfer of knowledge and know-how to students. In the case of discrete event system courses, it is important for a learner to locally or remotely control real systems (or plants) that are composed of many sensors and actuators. The use of these devices poses several problems. First, it is difficult to adapt them to the students level (from beginner to expert). Second, these systems are generally designed with industrial components. An error on the control-command design can involve safety problems and breakdowns. In this paper, the authors propose an original solution to solve these two problems. To guarantee the safety of the operators and the equipment, an approach using a validation filter is proposed. It is based on the definition of logical constraints, which should in no case be violated. To adapt the difficulty level, it is proposed to modify the level of automation. For that, the functional dimension of the automation system is modified to adapt the students level of autonomy. The level of automation is defined by the teacher by means of a functional analysis of the system. To validate the approach, it is applied to an original project with ten-year-old children on a packaging system. The aim of the project is to enable ldquoyoung novice control engineersrdquo to perform their first programmable logic controller program to control the whole system.

Prevention of human control errors by robust filter for manufacturing system

Abstract In this paper, we are interested at the errors that can commit by a human operator in the control program. When a command error is made, the presence of a product in the system can cause damage. In this paper, we design a robust filter placed inside the PLC which authorizes or forbids outputs from the PLC. The filter is composed of several logical constraints which have to be respected at each PLC cycle. In order to guarantee the filter quality, it is necessary to check that all constraints have been well defined. For that, in order to validate the filter, an original formal method has been proposed. This one is based on a modular modelling approach of the manufacturing system by using different timed automata models (actuators, sensors, items, and PLC), and by considering the most permissive PLC program. UPPAAL checker is used to verify that the filter is sufficient to avoid the manufacturing system to reach dangerous forbidden states. If it is the case, the filter guarantees the safety whatever the PLC program. Hence, the filter still remains active even if there are changes in the PLC program during the lifecycle of the production system.

SYNTHESIS OF SUPERVISED CONTROLLER BASED ON BOOLEAN CONSTRAINTS AND BOOLEAN AUTOMATA

Abstract In order to establish a method to synthesis controllers, an essential step is the modelling of both plant and constraints. However, this step remains a very complex task. To mitigate this difficulty and facilitate modelling, we present a methodology for plant modelling based on rules; as well as a user friendly methodology for constraints modelling based on logical equations in the traditional Boolean algebra. Then, we present an adaptation of the Kumar algorithm synthesis adequated to these new modelling. To conclude, we show that our synthesis approach can constitute a help in controller development and to be diverted from its first function to be used in controller validation.

Industrial risk prevention by robust filter for manufacturing control system

Abstract Environmental damages can come from control errors. Indeed, for instance, maintenance tasks and improvements in the manufacturing process involve changes in the PLC (programmable logic controller) program that can have bad security consequences. Hence, a PLC program which is at the beginning of the production lifecycle safety validated can become unsafe. Today, this problem is increased because remote maintenance monitoring is a reality in manufacturing systems. In this paper, we design a robust filter placed inside the PLC which authorizes or forbids outputs from the PLC. The filter is composed of several logical constraints which have to be respected at each PLC cycle. In order to guarantee the filter quality, it is necessary to check that all constraints have been well defined. For that, in order to validate the filter, an original formal method has been proposed. This one is based on a modular modelling approach of the manufacturing system by using different timed automata models (actuators, sensors, items, and PLC), and by considering the most permissive PLC program. UPPAAL checker is used to verify that the filter is sufficient to avoid that the manufacturing system reaches dangerous forbidden states. If it is the case, the filter guarantees the safety whatever the PLC program. Hence, the filter still remains active even if there are changes in the PLC program during the lifecycle of the production system.

Human-Machine Systems concepts applied to Control Engineering Education

In this paper, we interest us to Human-Machine Systems (HMS) concepts applied to Education. It is shown how the HMS framework enables to propose original solution in matter of education in the field of control engineering. We focus on practical courses on control of manufacturing systems. The proposed solution is based on an original use of real and large-scale systems instead of simulation. The main idea is to enable the student, whatever his/her level to control the whole system, from novice to expert, in a safety mode. The teacher is responsible for sharing the control design tasks between the student and the automatic system. Different teachers and students have tested this approach, on different manufacturing systems. By an experiment with a class of “10-year-old novice control engineer”, we have shown the interest and the power of the proposed solution. We have proposed at the children to realize their first control program of a packaging process. This experiment encountered a big success.

REQUIREMENT AND USE FOR REMOTE TEACHING OF DISCRETE EVENTS SYSTEMS

Today, Internet makes possible remote access to PLC (Programmable Logic Controllers) remote maintenance, monitoring, supervision and follow-up of plants. In this article, we are interested in the possibilities that Internet offers for the D.E.S (Discrete Events System) teaching. The concept of distributed practical work room is proposed in order to facilitate the technical know-how transmission. The idea consists for students, on the one hand to use a real PLC and specialized software via Internet and on the other hand, to check their controller program by the mean of a plant simulation. In addition, the controller program verification problem is proposed. Indeed, as well within the framework of the real as simulated plant use, it is necessary to develop controller verification tools able to cooperate with the teacher and students and having explanatory capacities.

Control validation of D.E.S systems: Application to remote laboratories

Objectives of Automation courses are knowledge and know-how transfer to students. It is important for learner to control locally or remotely real systems composed of many sensors and actuators. The use of these devices poses several problems. Firstly, it is difficult to adapt them to the student’s level (from beginner to expert). Secondly, these systems are generally designed with industrial components. An error on the control-command design can involve safety problems and breakdowns. Technologies today allow remote use of plant. That makes it possible to improve the availability of the work practice rooms but ask pedagogy and safety questions. In this paper, we propose an original solution to solve these 2 problems. In order to guarantee the safety of the operators and the equipment, an approach using a validation filter is proposed. It is based on the logical constraints which should in no case to be violated. In order to adapt the difficulty level, it is proposed to modify the level of automation. For that, the functional dimension of the automation system is modified to adapt the student’s level of autonomy. In order to validate the approach, we applied it to an original project with 10 year old children on a packaging system.

Prise en compte de l’état réel d’un système complexe pour l’aide à la décision en phase d’exploitation

Cet article propose un modele d’aide au choix de sequences de conduite pour les systemes critiques. L’objectif ici consiste a proposer un classement multicritere de sequences en integrant a la fois l’aspect securitaire, dans la definition des criteres de decision, et egalement l’etat reel des equipements et les connaissances metiers. Une methodologie structuree pour supporter le processus de classement est ainsi developpee. Les modeles proposes reposent sur la theorie de l’utilite multi-attributs et la notion de bilan de sante. Les entrees de ces modeles proviennent des donnees reelles et des connaissances metiers. En sortie, l’expert de la conduite dispose d’un ensemble d’informations consensuelles et objectives sur le systeme. La principale originalite de ce travail consiste en la combinaison d’information issue du suivi « on line » du systeme et d’un outil issu de l’aide a la decision dans un objectif de pilotage de SED.

Proposition of Plant Model for the Verification of System Safety

Abstract Previously, we define an approach that screens the dangerous evolutions to secure the manufacturing system. For that, a filter with a constraints set, is defined. Indeed, these constraints are located in a filter between the plant and the controller, to filter outputs which can damage the plant. In this paper, we propose a verification approach to ensure the sufficiency of constraints. This verification is performed by model checking that requires a system model (plant, Programmable Logic Controller evolution, and control program). This paper proposes a system model taking into account the computing environment as well as the technology of plant elements and system instrumentation. This model is proposed to make the verification of the constraints sufficiency. We propose a modular system modelling to consider each plant element separately, and considering each stage of the functional chain. The modelling tool used is timed automata because they enable to synchronise different models. An example of double-acting cylinder driven by a 5/2 air valve, illustrates this proposal.

REMOTE CONTROL OF AUTOMATION SYSTEMS FOR TRAINING

Abstract We are interested in the remote use of automated systems by students within the framework of Discrete Event Systems teaching. One of the most important problems in this case, is to guarantee that the proposed PLC (Programmable Logic Controller) control is correct; it is to say respecting the specifications given by the teacher. Hence, there is a validation problem of the control. To solve this problem, we propose an on-line validation approach based on a filter placed between the PLC and the plant. A second problem is the system dimension. Indeed, we propose an approach to keep a global vision adapted to the level of learners. For that, we propose a functional identification. We applied this method to an original project where some 9 year old children have discovered automation by programming a tablets packaging system.