Grafcet: Behavioural Issues and Control Synthesis

International audienceThis paper discusses the difficulties encountered in identifying the correct behaviour of Grafcet specifications in view of synthesising a correct control execution model. Formal algorithms for the synthesis of supervisory controllers related to Grafcet are also proposed. These algorithms consider the constraints induced by the behaviour of the controlled plant so as to identify the required correct behaviour of Grafcet during control execution. The resulting control execution is deadlock-free, and represents the minimal possible restriction of the behaviour of a given Grafcet, subject to a number of specified constraints

Synthesis of control implementation for discrete manufacturing systems

International audienceThe paper presents the concepts and steps required to synthesize a correct control implementation for discrete manufacturing systems, starting from Grafcet speci-® cations. A formal framework implementing the synthesis steps is also presented and illustrated with an example of a drilling system

A 6 DEGREES OF FREEDOM KINEMATICAL MODEL OF THE KNEE FOR THE DESIGN OF A NEW REHABILITATION DEVICE

International audienceIsokinetics devices are widely used in the field of knee rehabilitation. This kind of apparatus often solicits the knee joint in the sagittal plane with one degree of freedom. With the development of exoskeletons and intelligent prostheses, more precise control applications to assistive robotics for rehabilitation are possible. Our aim is to design a new apparatus for the 3 dimensional control of knee joint movements for sports training and rehabilitation. The first step to design such apparatus is to specify its kinematics. This paper presents a kinematical model of the knee joint that will be employed to specify the future Device kinematics and a preliminary control scheme

On The Nield-Koznetsov Integral Function and Its Application to Airys Inhomogeneous Boundary Value Problem

In this work, we provide a solution to a two-point boundary value problem that involves an inhomogeneous Airys differential equation with a variable forcing function. The solution is expressed in terms of the recently introduced Nield-Koznetsov integral function, Ni(x), and another conveniently defined integral function, Ki(x). The resulting expressions involving these integral functions are then evaluated using asymptotic and ascending series

Suivi de trajectoire d'un dispositif de rééducation des membres inférieurs - Approche multimodèles

International audienceCet article propose la commande en suivi de trajectoire d'un nouveau dispositif de rééducation des membres inférieurs en chaîne musculaire fermée. L'effort du patient appliqué sur cette machine est considéré comme une perturbation externe à la dynamique du système. Le modèle dynamique obtenu de ce dispositif est écrit sous forme d'un multimodèle de type Takagi-Sugeno (T-S). Une loi de commande de type non-PDC (Parallel-Distributed-Compensation) est synthétisée afin d'assurer le suivi de trajectoire de ce système en boucle fermée avec atténuation des perturbations externes. Des conditions de stabilité sont données sous forme d'inégalités linéaires matricielles en utilisant une fonction de Lyapunov non-quadratique. Enfin, la simulation d'un mouvement isocinétique illustre l'efficacité de l'approche proposée. Mots clés-Dispositif de rééducation, chaîne musculaire fermée, multimodèles, descripteurs, suivi de trajectoires, LMI

Integration of a failure monitoring within a hybrid dynamic simulation environment

The complexity and the size of the industrial chemical processes induce the monitoring of a growing number of process variables. Their knowledge is generally based on the measurements of system variables and on the physico-chemical models of the process. Nevertheless this information is imprecise because of process and measurement noise. So the research ways aim at developing new and more powerful techniques for the detection of process fault. In this work, we present a method for the fault detection based on the comparison between the real system and the reference model evolution generated by the extended Kalman filter. The reference model is simulated by the dynamic hybrid simulator, PrODHyS. It is a general object-oriented environment which provides common and reusable components designed for the development and the management of dynamic simulation of industrial systems. The use of this method is illustrated through a didactic example relating to the field of Chemical Process System Engineering

Dynamic state reconciliation and model-based fault detection for chemical processes

In this paper, we present a method for the fault detection based on the residual generation. The main idea is to reconstruct the outputs of the system from the measurements using the extended Kalman filter. The estimations are compared to the values of the reference model and so, deviations are interpreted as possible faults. The reference model is simulated by the dynamic hybrid simulator, PrODHyS. The use of this method is illustrated through an application in the field of chemical processe

Methicillin-resistant Staphylococcus aureus in poultry- an emerging concern related to future epidemic

Methicillin resistant – Staphylococcus aureus (MRSA) is an organism responsible for causing deadly infections in man, poultry and several other animal species. Ever since the discovery of MRSA in decade of 1960’s, it has been isolated and reported in live poultry birds and their meat products worldwide. Strikingly, MRSA recovered from poultry share a common ancestry with MRSA isolates of human and animal origin. Furthermore, MRSA colonizes the skin and mucous membranes of both man and poultry. This colonizing ability of MRSA is not only a cause of non-responsive infections in poultry but it can also be transferred to the humans handling birds at farms and slaughter houses. Moreover, the consumers of poultry meat can also acquire its infection. The cases of cross infections of MRSA between poultry and human has been reported. However, the most important difficulty to control MRSA and its interspecies transmission is the irrational use of antimicrobial drugs and inadequate biosecurity measures. Therefore, rational usage of antimicrobials and good biosecurity measures need to be adopted for prevention and control of zoonotic MRSA infections. This paper reviews the existing status of MRSA in poultry as a possible threat of zoonosis