Supervisory Control (supervisory + control)

Distribution by Scientific Domains


Selected Abstracts


NON-BLOCKING SUPERVISORY CONTROL FOR INITIALISED RECTANGULAR AUTOMATA

ASIAN JOURNAL OF CONTROL, Issue 2 2004
Michael P. Spathopoulos
ABSTRACT We consider the problem of supervisory control for a class of rectangular automata and more specifically for compact rectangular automata with uniform rectangular activity, i.e. initialised. The supervisory controller is state feedback and disables discrete-event transitions in order to solve the non-blocking forbidden state problem. The non-blocking problem is defined under both strong and weak conditions. For the latter maximally permissive solutions that are computable on a finite quotient space characterised by language equivalence are derived. [source]


Flexible manufacturing cell SCADA system for educational purposes

COMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 1 2008
Sarah Reynard
Abstract This article deals with the development of a Supervisory Control and Data Acquisition SCADA system to be used in a flexible manufacturing cell for educational purposes in different automation engineering fields (SCADA development, PLC programming and industrial communications). When dealing with industrial communications or PLC programming the SCADA is employed as a supervision tool. In the other hand, when teaching SCADA systems the application will be developed by the students and the SCADA presented in this article is employed as a model. The application communicates through Internet with four controllers, by means of an OPC server, visualizes comprehensive information about the elements of the cell, includes the video streaming of an IP camera, and features traceability and report generation capabilities. © 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 16: 21,30, 2008; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20115 [source]


Operative Platform Applied to Building Automation

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 1 2009
Joćo Figueiredo
This structure is composed by three interrelated levels: the Operational level,where the field equipment is controlled, the Inter-Active level,where inhabitants communicate the building their preferences regarding control variables (lights, temperature, etc.), and the higher-level control, the Overall Building Well-Being Model, which manages the global building, taking into account the optimization of the inhabitants preferences, constrained by the available resources. At this third level, the inter-building communication is available. Each building has the capability to communicate with its neighbors, informing about fires, floods, security problems, power consumption expectations, and so on. This article implements one of the three above-referred interrelated control levels: the Operational-level control. This operative platform is structured over a cascade hierarchical control architecture where inner loops are performed by local PLCs (Programmable Logic Controllers), and the outer loop is managed by a centralized SCADA system (Supervisory Control and Data Acquisition) that interacts with the entire PLC network. The lower-level control loop assures high processing velocity tasks, the upper-level control loop updates the local references, knowing the complete system state. This operative model is tested on two prototypes, where all instrumentation in place is controlled by the industrial PLC network. Both prototypes worked perfectly showing the huge potential of communication systems between distributed processes. These communication systems allow intelligent centralized algorithms to manage decision-making problems in real-time environments. The system presented in this article combines several technologies (local PLCs, SCADA systems, and network communications) to reach the goal of efficient management of intelligent buildings. [source]


A fuzzy logical vigilance alarm system for improving situation awareness and trust in supervisory control

HUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 4 2006
Cheng-Li Liu
An automation system's operating performance is judged by how well an automation unit is monitored and maintained by its supervisors. Previous research has shown that situation awareness (SA) and trust are critical factors in automation. The purpose of this study was to evaluate and improve supervisory performance in automation manufacturing. First, a conceptual structure of the relationship among SA, trust, and vigilance was developed. Second, a quantitative vigilance performance-measuring model (, value) was proposed. Third, a matrix experiment based on orthogonal arrays through a simulated system of an auxiliary feed-water system (AFWS) was conducted to verify the effect of the measuring model. Finally, according to the vigilance performance-measuring model, a fuzzy logical vigilance alarm system was constructed to improve operating performance. The results of the first experiment indicated that the , value on human dynamic decision-making characteristics was easy and objective in the measurement of operators' vigilance. With greater vigilance, there is a greater likelihood of making appropriate SA and acquiring more trust in automation. The results of the second experiment indicated that applying the , value to the design of the fuzzy logical vigilance alarm system could improve supervisory performance efficiently. Therefore, an adaptive vigilance performance-measuring model combined with a fuzzy technique applied to the design of a human,machine interface for the improvement of cognitive decision making and operating performance is an important new direction in automation manufacturing. © 2006 Wiley Periodicals, Inc. Hum Factors Man 16: 409,426, 2006. [source]


Designing predictors for MIMO switching supervisory control

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 3 2001
Edoardo Mosca
Abstract The paper studies the problem of inferring the behaviour of a linear feedback loop made up by an uncertain MIMO plant and a given candidate controller from data taken from the plant possibly driven by a different controller. In such a context, it is shown here that a convenient tool to work with is a quantity called normalized discrepancy. This is a measure of mismatch between the loop made up by the unknown plant in feedback with the candidate controller and the nominal ,tuned-loop' related to the same candidate controller. It is shown that discrepancy can in principle be obtained by resorting to the concept of a virtual reference, and conveniently computed in real time by suitably filtering an output prediction error. The latter result is of relevant practical value for on-line implementation and of paramount importance in switching supervisory control of uncertain plants, particularly in the case of a coarse distribution of candidate models. Copyright © 2001 John Wiley & Sons, Ltd. [source]


Fault-tolerant control of process systems using communication networks

AICHE JOURNAL, Issue 6 2005
Nael H. El-Farra
Abstract A methodology for the design of fault-tolerant control systems for chemical plants with distributed interconnected processing units is presented. Bringing together tools from Lyapunov-based nonlinear control and hybrid systems theory, the approach is based on a hierarchical architecture that integrates lower-level feedback control of the individual units with upper-level logic-based supervisory control over communication networks. The local control system for each unit consists of a family of control configurations for each of which a stabilizing feedback controller is designed and the stability region is explicitly characterized. The actuators and sensors of each configuration are connected, via a local communication network, to a local supervisor that orchestrates switching between the constituent configurations, on the basis of the stability regions, in the event of failures. The local supervisors communicate, through a plant-wide communication network, with a plant supervisor responsible for monitoring the different units and coordinating their responses in a way that minimizes the propagation of failure effects. The communication logic is designed to ensure efficient transmission of information between units, while also respecting the inherent limitations in network resources by minimizing unnecessary network usage and accounting explicitly for the effects of possible delays due to fault-detection, control computations, network communication and actuator activation. The proposed approach provides explicit guidelines for managing the various interplays between the coupled tasks of feedback control, fault-tolerance and communication. The efficacy of the proposed approach is demonstrated through chemical process examples. © 2005 American Institute of Chemical Engineers AIChE J, 2005 [source]


NON-BLOCKING SUPERVISORY CONTROL FOR INITIALISED RECTANGULAR AUTOMATA

ASIAN JOURNAL OF CONTROL, Issue 2 2004
Michael P. Spathopoulos
ABSTRACT We consider the problem of supervisory control for a class of rectangular automata and more specifically for compact rectangular automata with uniform rectangular activity, i.e. initialised. The supervisory controller is state feedback and disables discrete-event transitions in order to solve the non-blocking forbidden state problem. The non-blocking problem is defined under both strong and weak conditions. For the latter maximally permissive solutions that are computable on a finite quotient space characterised by language equivalence are derived. [source]