Mohieddine Jelali

Technische Hochschule Köln | FH Köln · Institute of Product Development and Design Technology

The highly individualized production processes for long products in the steel industry is subject to a variety of influencing variables with mutual interactions in a complex manner. To handle this complexity, modern data mining methods can be used for a highly efficient analysis of process data, to detect process anomalies in the process data, e.g....

Metal production is still permeated by brown-field environments which are continuously becoming increasingly digitized. Therefore, smart and superordinate approaches facilitating autonomous decision-support systems and plant control, while accompanying the running production, are fundamental for the modernization progress. Cyber Physical Production...

The occurrence of anomalies and unexpected, process-related faults is a major problem for manufacturing systems, which has a significant impact on product quality. Early detection of anomalies is therefore of central importance in order to create sufficient room for maneuver to take countermeasures and ensure product quality. This paper investigate...

Die Ausstattung von Warmbandstraßen mit präzisen, genauen und robusten Messsystemen ist eine elementare Voraussetzung für die Verbesserung der Produktqualität und die Reduzierung des Energieverbrauchs, sowie der Erhöhung der Lebensdauer der Anlagen. Zu diesem Zweck arbeitet ein multidisziplinäres Konsortium an der Entwicklung von radargestützten Me...

Aims and objectives: Providing the first meta-analysis of risk factors for pressure ulcer development in adult patients. Background: Pressure ulcers remain a serious health complication for patients and nursing staff. However, there is a lack of statistical evidence for risk factors as previous research did not include any quantitative synthesis...

Stahlproduzenten wünschen sich in den nächsten Jahren, ihre Messsysteme zu modernisieren bzw. durch neue zu ersetzen, bei denen aufwendige Präventionsmaßnahmen zur Arbeitssicherheit entfallen. Anstelle von radiometrischen und optischen Systemen sollen robuste radarbasierte Systeme treten, die eine berührungslose und hochpräzise Erfassung von Bramme...

Pressure injuries remain a serious health complication for patients and nursing staff. Evidence from the past decade has not been analysed through narrative synthesis yet. PubMed, Embase, CINAHL Complete, Web of Science, Cochrane Library, and other reviews/sources were screened. Risk of bias was evaluated using a slightly modified QUIPS tool. Risk...

In this paper, an approach to recursive subspace identification based on a the coordinate-free framework of subspace identification is proposed. Herein, the predictor space serves as a natural basis for the formulation of a recursive approach. Compressing the necessary past information, a predictor space from a previous identification will be used...

Strict conditions in steel production and processing complicate usage of sensors in rolling, thereby determination of strip parameters and characteristics of technological process can be either sometimes realized approximately, or it can be impossible at any process stages. The results obtained lately in the field of development of radar technics i...

Control loop performance monitoring (CPM) in industrial production processes is an established area of research for which many methods to detect malfunctioning loops have been developed. However, it is unclear which methods are successful in an industrial environment. Often, there are additional aspects such as organizational issues, data availabil...

A recent identification study using the Tennessee Eastman Process model revealed that the MOESP-based (multiple-input multiple-output output error state space) algorithm (i.e. implementation) of the subspace identification method ORT (orthogonal decomposition) underachieves given this realistic benchmark example. In this paper, the cause of this un...

A new, comprehensive mathematical model of continuous annealing furnaces is developed, under consideration of both the radiative and convective heat transfer of the furnace components. Based on measured normal operating data from an industrial stainless steel plant, parameter identification is basically carried out using a nonlinear least-squares o...

This paper deals with the thickness control of single cold rolling mills and with the combined thickness and tension control of tandem cold rolling mills. It is shown that PI(D) controllers can be effectively replaced by the predictive functional control (PFC), which can be easily implemented and tuned under industrial automation environments. The...

To reduce downtimes and extend the lifetime of components, fault detection and identification become more important in production plants. Sensors and other information sources can be deployed for condition monitoring and fault diagnosis. In this contribution, first a review on the application of Short-time Fourier transform, continuous and discrete...

Increasing customer demands in product quality and increasing complexity in production plants found the need of profound system knowledge to reduce downtimes, to extend the lifetime of components, and to reduce the deterioration of quality. In this contribution, the application of Wavelet Transform and Empirical Mode Decomposition to selected indus...

In this paper, a closer look at the underlying computer code of the well-known Tennessee Eastman Process model is taken. Since its introduction in the 1990s typical simulation software, e.g. MATLAB®, which is used to simulate the process model, has changed. Thus the original program flow devised by Downs & Vogel no longer holds. This results in pro...

The aim of COGNITVE CONTROL was to create cognitive automation systems with the capabilities automatic control performance monitoring (CPM), self-detection and automatic diagnosis of faults (sensors, actuators, controller) and self-adaptation in control system environments to optimise the product quality and minimise energy consumption in steel dur...

Das Handbuch der Prozessautomation ist ein Standardwerk für die Planung verfahrenstechnischer Anlagen. In der 5., überarbeiteten Version geht es auf die Herausforderung bei der Digitalisierung der Anlage ein. Das Handbuch wurde von fast 50 Experten mit umfassenden Praxiskenntnissen gestaltet und deckt das gesamte Feld der Prozessautomatisierung ab....

In order to optimize rolling processes and to increase strip quality and the productivity of rolling mills, Andritz Sundwig has developed a modular and universally applicable flatness model for all types of rolling mills with configurable flatness actuators. The model takes into account all effects and components involved in the flatness developmen...

Um Walzprozesse zu optimieren und die Bandqualität und Produktivität von Walzanlagen weiter zu steigern, hat die ANDRITZ Sundwig GmbH ein modular aufgebautes und universell für alle Gerüsttypen einsetzbares Planheitsmodell mit konfigurierbaren Planheitsstellgliedern entwickelt. Das Modell berücksichtigt alle an der Planheitsausbildung beteiligten E...

In existing production plants, sensor systems and other sources provide information about the plant condition. This paper presents methods for how data can be conveniently summarized, treated, and evaluated to retain characteristic features and allocate them to certain faults respectively to use them for monitoring purposes. This work details the d...

This paper combines the use of the Harris index and the relative damping index (RDI) to a new method for CPM-based controller tuning. The RDI is defined based on the disturbance impulse repsonse, which is calculated as byproduct of the Harris index. The proposed technique provides controller settings that attain the best-achievable performance by c...

In this paper, subspace identification methods are compared regarding their capability to cope with process disturbances occurring in complex plants. The Tennessee Eastman process is considered to be a realistic simulation model of chemical processes. The MOESP, N4SID and ORT methods as well as some of their variants are applied to data gathered fr...

This paper investigates the use of the standard available measured signals in a hydraulic system (the pressure signals of the two hydraulic cylinder chambers) to develop a modular signal-based monitoring system. The developed system has to detect and classify the typical faults that can occur in the hydraulic systems, e.g. internal leakage, dynamic...

This contribution describes a predictive maintenance strategy through a modelbased condition monitoring scheme for hydraulic systems in rolling mills, with specific application to the wrapper roll control of a hot strip coiler. For this purpose, a diagnosis strategy is developed using the Unscented Kalman Filter (UKF) technique based on typically a...

Within the present project, different strategies have been considered in order to establish a coordinated approach to the coil processing with the focus on the product through different facilities. Different features and tools have been developed for analysing, monitoring and optimisation of strip flatness from entry of cold rolling to the exit of...

Systems in some industrial fields, such as power and servo industry and robotics, show references and disturbances tending to be more deterministic rather than stochastic. In these cases, the processes are operated with frequent changes in the references and hence output levels. So, for such systems, deterministic assessment techniques are needed....

The aim of statistical process control (SPC) techniques, when applied to control-loop operating data, is to identify and track certain variation within the loop, and thus highlight situations that show abnormal behaviour, i.e. statistically significant events or abnormalities. Indeed, understanding this variation may be a first step towards the imp...

Since a control loop may exhibit poor performance for various reasons, it is not only important to detect poor performance, but the challenge is to trace the bad performance to its root cause. Not only controller design and tuning but also other elements in the control systems, such as sensors and actuators, are often responsible for the poor perfo...

The final and most challenging objective of applying performance assessment methods and indices should always be to suggest measures to improve the control or process/plant performance. Even in the case where the loop is found to work at acceptable performance level, it is useful to know how the performance can be improved to attain top level. In t...

Control valves are the most commonly used actuators or final control elements in the process industries. Many surveys indicate that about 20–30 % of all control loops oscillate due to valve problems caused by valve nonlinearities, such as stiction, hysteresis, dead-band or dead-zone. Many control loops in process plants perform poorly due to valve...

The standard control performance assessment methods are based on the minimum-variance (MV) principle or modifications of it. The key point is that the MV benchmark (as a reference performance bound) can be estimated from routine operating data without additional experiments, provided that the system delay is known or can be estimated with sufficien...

Minimum-variance benchmarking only considers the most fundamental performance limitation of a control loop owing to the existence of time delays. In practice, however, there are many other limitations on the achievable control performance, such as constraints on controller order, structure, and action. Many researchers have introduced modified/exte...

When a control loop is detected to be oscillating, the root cause of that oscillation may be aggressive controller tuning, external disturbance, or valve nonlinearity, particularly stiction. Even in the case where stiction is detected by applying any of the techniques described in Chap. 11, it is desirable to quantify the extent of stiction. This c...

Performance assessment algorithms contain many options and parameters that must be specified by the user. These factors substantially affect the accuracy and acceptability of the results of assessment exercises. A fundamental basis for performance assessment is to record and carefully inspect suitable closed-loop data. Pre-processing operations, wh...

Numerous investigations have shown that the performance of control systems in the process industries is not satisfactory. This particularly applies for the steel industry, where it is the norm to perform controller tuning only at the commissioning stage and then never again. A loop that worked well at one time is prone to degradation over time unle...

This chapter deals with extensions of the MV benchmark that need substantially more information about the plant than just the time delay. An extension of the MV benchmark is the approach of generalised MV (GMV) benchmarking, minimising a weighted sum of the control error and control effort. More general but rigorous extensions are the linear-quadra...

In practice, it is the norm to perform controller tuning only at the commissioning stage and never again. A control loop that worked well at one time is prone to degradation over time unless regular maintenance is undertaken. Typically, 30 % of industrial loops have poor tuning, and 85 % of loops have sub-optimal tuning. There are many reasons for...

The growing acceptance of the CPM technology in some industries is due to the awareness that control software is recognised to be a capital asset that should be maintained, monitored and revised routinely. Control systems permanently showing top performance significantly reduce or even avoid product-quality degradation, loss of energy resources, wa...

Most of control performance methods assume that the system is (at least locally) linear. However, the presence of certain type of nonlinearity may cause severe performance problems. For instance, stiction, hysteresis and dead-band in actuators, or faulty sensors can induce unwanted oscillations. Thus, it is recommended to evaluate “how linear (or n...

Since the loops in multivariable control systems can be coupled, a multivariable control strategy can further reduce process variations, thus, only multivariable assessment can provide the right measure of performance improvement potential in the general case. In this chapter, methods for multivariable minimum-variance benchmarking are presented: i...

This contribution is about control performance monitoring (CPM) technology in metal processing plants. It is shown how to explore not yet discovered opportunities for controller performance improvement in this industrially interesting field, where special aspects have to be considered. The paper presents one industrial case study of the performance...

For cold rolled flat products, strip thickness and flatness are major quality parameters. However, the control of these two quality parameters with high performance is not independently possible with standard systems. Thickness and flatness control have got an influence on each other. To avoid thickness deviations through the flatness controller, n...

Zusammenfassung Die Produktion von Edelstahlfeinblech erfolgt meist an 20-Rollenwalzenwerken. Diese stellen komplexe und totzeitbehaftete Mehrgrößensysteme dar, bei denen Banddicke und Bandplanheit als wichtigste Qualitätsmerkmale in optimaler Weise geregelt werden müssen. Dabei ist die gegenseitige Kopplung zwischen den beiden Qualitätsgrößen, ins...

Zusammenfassung Ein besonders häufiges Problem in der Prozessindustrie ist das Auftreten oszillatorischer Verläufe der Signale in Regelkreisen. Diese führen unter anderem zu einer erhöhten Streuung der Produktqualität, zu einem erhöhten Energiebedarf, zu Produktivitätsverlusten sowie zu erhöhtem Komponentenverschleiß. Der Beitrag stellt ein neues V...

Product quality, operation safety, material and energy consumption, and thus the financial performance of industrial plants are directly or indirectly linked to the performance of control systems. Since process control systems are very complex, usually comprising different hierarchy levels, it is hopeless to maintain them on regular basis by plant...

Oscillations in process control loops are a very common problem. Oscillations often indicate a more severe problem than irregular variability. The presence of oscillations in a control loop increases the deviations from the setpoint of the process variables, thus causing inferior products, larger rejection rates, increased energy consumption and re...

This chapter contains an exhaustive comparative study of methods for detecting stiction in control valves. The study involves 93 different data sets from different process industries, including chemicals, pulp and paper mills, commercial building, and metal processing. The different techniques considered in the study are assessed in terms of effici...

To close this book, let us reiterate the goal of the book and ponder what we have achieved. As stated in the introduction, the aim of control loops is to maintain processes at the desired operating conditions, safely and efficiently. A poorly performing control loop can result in disrupted process operations, degraded product quality, higher materi...

This introductory chapter explains the role of control valves in the process industry and the motivation for the detection of valve stiction in control loops. It reviews some definitions of the term “stiction” and similar phenomena (deadband, backlash, hysteresis, etc.) that can occur in control valves. Some basic analysis tools will be described,...

This chapter presents a new procedure for quantifying valve stiction in control loops based on global optimisation. Measurements of the controlled variable (PV) and controller output (OP) are used to estimate the parameters of a Hammerstein system, consisting of a connection of a two-parameter stiction model and a linear low-order process model. As...

Zusammenfassung Die Bandplanheit stellt eines der wichtigsten Qualitätsmerkmale der gewalzten Erzeugnisse (Grobblech, Band und Folie), die in vielen Industriezweigen wie der Auto-mobil-, Bau-, Haushalts- und Verpackungsindustrie benötigt werden, dar. Beim betrachteten Walzprozess handelt es sich um ein totzeitbehaftetes und zum Teil stark gestörtes...

This contribution presents a new procedure for quantifying valve stiction in control loops based on global optimisation. Measurements of the controlled variable (PV) and controller output (OP) are used to estimate the parameters of a Hammerstein system, consisting of a connection of a two-parameter stiction model and a linear low-order process mode...

This contribution takes the control performance monitoring (CPM) technology into a new industrial area, the metal processing, where not much work has been done before. It is shown how to explore not yet discovered opportunities for controller performance improvement in this industrially interesting field, where special aspects have to be considered...

In the process industry there is an increasing interest in control performance monitoring (CPM) as a component of comprehensive and effective plant condition monitoring. This paper presents new approaches for automatic controller tuning based on CPM methods and indices. The aim is to optimise the performance of control loops being identified as poo...

A review of the current status in control performance assessment (CPA) technology and industrial applications is presented. Merits and drawbacks of each CPA method are highlighted. An evaluation of publications during the last 15 years shows some trends in the application of a number of CPA metrics and methods in different process industries. Also...

Die Automatisierungssysteme in der Metallindustrie sind in der Regel hierarchisch, d. h. aus mehreren Ebenen aufgebaut, wobei jede Ebene eine große Anzahl von Regelkreisen beinhaltet. Dieser Teil 2 der Arbeit stellt ein neues systematisches Konzept zur kontinuierlichen Regelkreisüberwachung in solchen Automatisierungssystemen vor. Die dabei gewählt...

In der Praxis zeigt sich, dass ein hoher Prozentsatz der Regelkreise in der Metallindustrie aufgrund von fehlender Instandhaltung und Optimierung Performanceprobleme hat. Daher ist es dringend geboten, eine fortlaufende Bewertung und Überwachung der Reglerperformance einzuführen. Teil 1 dieses Beitrages unterteilt die Methoden des Control Performan...

An overview of the current status and future trends in control performance assessment (CPA) technology and applications in the metal processing sector is presented. The sources of poor control performance are discussed, and desired properties of CPM algorithms and tools are stated. A systematic concept for continuous control performance monitoring...

Surface finishing plays an important role in the metal processing industry. Galvanised strips are coated on both sides with one or more paint layers to get desired surface properties like colour, corrosion resistance and so on. The strips are then processed into, e.g., washing machines, electrical control cabinets, car parts, etc. Therefore, lacque...

The efficiency of automatic flatness control systems in tandem cold mills is mainly based on the accuracy of the prediction models and on the selection of optimum control concepts. BFI, together with EKO Stahl, has recently developed and partly applied advanced flatness control strategies (providing online-adaptation of actuator action to thickness...

The purpose of this chapter is to give a survey of basic and advanced control design methods for HSSs, including theoretical background and application to selected models derived in Chapters 4 and 5. The benefits and limitations associated with standard control design approaches are reviewed. Recent advances in the area of control theory, involving...

In Chapter 4, theoretical models of hydraulic servo-systems have been presented and analysed. The subsystem models of hydraulic servo-systems have been brought into representations, which are suitable for controller design. This finally led to simple models, describing the relevant dynamics and non-linearities of the systems, which form the basis f...

The purpose of this chapter is to define some physical properties of hydraulic fluids, and to discuss the fundamental laws and equations of fluid motion, types of flow, and the flow through orifices and valves. It should be mentioned that the intention of this chapter is not to present the complete theoretical basics of fluid motion in hydraulics (...

This chapter contains a general characterisation of hydraulic servo-systems with some fundamental definitions and a brief description of a number of subsystems of hydraulic servo-systems. It is neither within the scope of this chapter nor our intention to go into the function/construction details of the different subsystems. For this, the reader sh...

In this chapter, some case studies of the use of selected methods for modelling and control of HSSs are described to demonstrate the performance and different aspects of the methodologies presented in this book. Emphasis is placed on the comparison of widely used classical (mostly linear) approaches with advanced (usually nonlinear) strategies conc...

This chapter is devoted to the derivation of physical models for hydraulic servo-systems and includes the most relevant dynamic and non-linear effects that are involved in hydraulic servo-systems. The model derivation is based on the physical fundamentals described in Chapter 3 and on first principles. Many assumptions and simplifications must be m...

The application of new measurement systems and the optimisation of process control are major measures for better exploitation of plant potentials. The optical flatness measurement system TopPlan fulfils the demands for high resolution and reproducibility, low cost investment and running costs, and it provides the three-dimensional determination of...

The efficiency of automatic flatness control systems in hot rolling mills is based mainly on the capability of the installed instrumentation to provide accurate flatness measurements, on accurate prediction models, and on the selection of an optimum control concept. BFI, together with Thyssen Krupp Stahl, has recently developed a new topometric fla...

The application of advanced (multivariable) control strategies yields significant improvement in the quality of rolled products. For instance, the beneficial effects of orthogonal Smith Predictor based control developed by BFI lead to rapid, consistent and reliable elimination of flatness deviations over the whole strip length. The control concept...

This contribution aims to present a compact and efficient model for the calculation of strip thickness profile and shape which refers to the tension stress distribution. The model is derived from appropriate combination and generalization of analytical approaches well known in the published literature. The basis for the model is given from analytic...

A new dynamic mill simulator has been developed, acting as a realistic environment for controller evaluation as well as enabling the development of linear state-space models for controller synthesis. The construction of the simulator is performed in a modular fashion with the help of a series of interlinked blocks and various levels of hierarchy. C...

Thesis--Gerhard-Mercator-Universitat-Gesamthochschule.