Rony Ghostine

Variable delays and message losses: Influence on the reliability of a control loop

Today, new technologies (distributed systems, networks communication) are more and more integrated for applications needing to fit real-time and critical constraints. It means that we require more and more to integrate these new technology-based components in systems or sub-systems dedicated to safety or dealing with a high level of criticality. Control systems are generally evaluated as a function of required performances (overshoot, rising time, response time) under the condition to respect a stability condition. Reliability evaluation of such systems is not trivial, because generally classical methods do not take into account time and dynamic properties which are the bases of control systems. The methodology proposed in this paper deals with an approach for the dependability evaluation of control systems, based on Monte-Carlo simulation, giving a contribution to the integration of automatic control and dependability constraints.

DEPENDABILITY EVALUATION OF NETWORKED CONTROL SYSTEMS UNDER TRANSMISSION FAULTS

Abstract The validation of network systems is mandatory to guarantee the dependability levels, that international standard impose in many safety-critical applications. This article presents a framework for the dependability evaluation of a networked control system (NCS) taking into account the network behaviour when transition faults occurs. CAN-based systems are studied and a proposed method is described with an example.

A Framework for the Reliability Evaluation of Networked Control Systems

Abstract this paper presents a framework to enable the analysis of the influence of the transmission faults on the reliability of a networked control system (NCS). The approach is composed of two parts: a modelling part in which all the basic components of a networked control system are modelled and a simulation part in which simulation is done on the models to evaluate the reliability. Due to external perturbations transmission faults may occur on the medium decreasing network quality of service and system performance. These aspects are difficult to assess with traditional dependability method like fault trees and reliability blocks. Our approach is applied to a case study example. The results show that our framework is an effective way for the reliability evaluation of networked control systems.

DEFINITION AND MODELLING OF THE COMMUNICATION ARCHITECTURE FOR THE CONTROL OF A HELICOPTER-DRONE

Abstract This paper presents a laboratory mini-helicopter model and its implementation and simulation as a networked control system. A model of the mini-helicopter, together with the choice of a communication architecture, is proposed. Simulations are effected to study the mentioned system as a networked control system in consideration of network delays, etc. Proposed simulations are achieved thanks to the TrueTime framework which is a Matlab / Simulink based toolbox. This toolbox provides several types of networks which are briefly described in the paper. The mentioned system is simulated by using two types of networks – CAN and Ethernet wire network. Results show differences in quantitative deviations among simulations of the mini-helicopter as system without network and with network.

INFLUENCE OF TRANSMISSION FAULTS ON THE DEPENDABILITY LEVEL OF NETWORKED CONTROL SYSTEMS: APPLICATION TO A CONTROL LOOP

The development of new technologies for automation, particularly the use of networks (notably wireless networks) and the generalisation of digital components, allows envisaging their use in several kinds of applications, with an induced low cost, particularly in embedded systems. When designing such digital-based systems, we must take care of the dependability level of these systems. Due to the complexity of these architectures, it is not trivial to evaluate this dependability level. The present paper proposes a modelling strategy in order to achieve this evaluation, with an application to a control loop.

Dependability Evaluation of Networked Control Systems Under Transmission Faults

: The validation of network systems is mandatory to guarantee the dependability levels, that international standard impose in many safety-critical applications. This article presents a framework for the dependability evaluation of a networked control system (NCS) taking into account the network behaviour when transition faults occurs. CAN-based systems are studied and a proposed method is described with an example. Copyright