Advances in PID Control

Since the foundation and up to the current state-of-the-art in control engineering, the problems of PID control steadily attract great attention of numerous researchers and remain inexhaustible source of new ideas for process of control system design and industrial applications. PID control effectiveness is usually caused by the nature of dynamical processes, conditioned that the majority of the industrial dynamical processes are well described by simple dynamic model of the first or second order. The efficacy of PID controllers vastly falls in case of complicated dynamics, nonlinearities, and varying parameters of the plant. This gives a pulse to further researches in the field of PID control. Consequently, the problems of advanced PID control system design methodologies, rules of adaptive PID control, self-tuning procedures, and particularly robustness and transient performance for nonlinear systems, still remain as the areas of the lively interests for many scientists and researchers at the present time. The recent research results presented in this book provide new ideas for improved performance of PID control applications

Design and Implementation of Modern Controls for Drive and Suspension of a High Speed Double Conical Bearingless Motor on a Real-Time System

In this work, modern control approaches for drive and suspension of a high speed double conical bearingless motor are designed. Firstly, the air gap flux density and the forces acting on the rotor are analytically calculated. Subsequently, an elaborate model of the magnetically levitated rotor is developed, which considers the non-collocation of position sensors and levitation windings as well as the presence of angular motion. Three different control approaches are designed and simulated. The first approach comprises a state controller augmented with integral action, with which the closed loop dynamics are freely defined after pole placement. The other two approaches concern Linear Quadratic Gaussian and Model Predictive control. The pole placement control approach is tested successfully on the test bench with the real motor. Sinusoidal disturbance forces, with the rotational frequency, can cause large rotor orbits and may drive the inverters to their limits. For this reason, two synchronous filtering control strategies are developed. Using Imbalance Force Compensation, the rotor can be driven with low orbits at relatively low speed and using Imbalance Force Rejection, the rotor can be driven with low levitation currents at high speed. The control performance is evaluated by measurements and the measured frequency response of the closed loop system is presented

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Investigation of a Neural Network Methodology to Predict Transient Performance in Fms

Most rapid analytical evaluative models for Flexible Manufacturing Systems (FMSs) are based on the steady-state performance. There is a practical need to develop robust, easy to construct, and transportable transient-state evaluative models for FMSs. This study proposes an ANN based metamodeling framework that can capture various post disruption system behaviors of FMS. The proposed ANN based meta-modeling scheme consists of a hierarchical taxonomy of mutilple ANNs. Each set of ANNs collectively represents a different part of the underlying system modeling domain. The taxonomical arrangement of multiple ANNs overcomes shortcomings often found in single ANN based meta-modeling schemes. These shortcomings are generally related to the limited knowledge acquisition capability of these schemes. The study uses an Extend based discrete simulation model that is built after an experimental FMS with a limited disruption trigger and handling capabilities. The simulation model is used to study various post-disruption behaviors by a given FMS and to study the feasibility of the proposed modeling scheme as a viable means to provide "lookahead" capability for a low level controller.Findings and Conclusions: The proposed ANN based metamodeling approach using multiple ANNs, in a taxonomically organized modeling structure, is an efficient way to capture multiple target performance index observation processes with a similar overall post-disruption behavior pattern. Despite its accuracy issues, this methodology was proven especially effective when it has to deal with noisy time series such as TIS at observation under a data rich environment. The study is to prove that the proposed methodology could be a viable means to model transient system behaviors. As long as individual observation processes of the selected performance index can keep their variances smaller among themselves, the accuracy of the overall model would be acceptable. This non-parametric performance modeling technique using hierarchically organized multiple ANNs, is worth further investigation.Industrial Engineering & Managemen

Ingénierie de modèle pour la sécurité des systèmes critiques ferroviaires

Development and application of formal languages are a long-standing challenge within the computer science domain. One particular challenge is the acceptance of industry. This thesis presents some model-based methodologies for modelling and verification of the French railway interlocking systems (RIS). The first issue is the modellization of interlocking system by coloured Petri nets (CPNs). A generic and compact modelling framework is introduced, in which the interlocking rules are modelled in a hierarchical structure while the railway layout is modelled in a geographical perspective. Then, a modelling pattern is presented, which is a parameterized model respecting the French national rules. It is a reusable solution that can be applied in different stations. Then, an event-based concept is brought into the modelling process of low-level part of RIS to better describe internal interactions of relay-based logic. The second issue is the transformation of coloured Petri nets into B machines, which can help designers on the way from analysis to implementation. Firstly, a detailed mapping methodology from non-hierarchical CPNs to abstract B machine notations is presented. Then the hierarchy and the transition priority of CPNs are successively integrated into the mapping process, in order to enrich the adaptability of the transformation. This transformation is compatible with various types of colour sets and the transformed B machines can be automatically proved by Atelier B. All these works at different levels contribute towards a global safe analysis frameworkLe développement et l’application des langages formels sont un défi à long terme pour la science informatique. Un enjeu particulier est l’acceptation par l’industrie. Cette thèse présente une approche pour la modélisation et la vérification des postes d’aiguillage français. La première question est la modélisation du système d’enclenchement par les réseaux de Petri colorés (RdPC). Un cadre de modélisation générique et compact est introduit, dans lequel les règles d’enclenchement sont modélisées dans une structure hiérarchique, tandis que les installations sont modélisées dans une perspective géographique. Ensuite, un patron de modèle est présenté. C’est un modèle paramétré qui intègre les règles nationales françaises qui peut être appliquée pour différentes gares. Puis, un concept basé sur l’événement est présenté dans le processus de modélisation des parties basses des postes d’aiguillage. La deuxième question est la transformation des RdPCs en machines B, qui va aider les concepteurs sur la route de l’analyse à application. Tout d’abord, une méthodologie détaillée, s’appuyant sur une table de correspondance, du RdPCs non-hiérarchiques vers les notations B est présentée. Ensuite, la hiérarchie et la priorité des transitions du RdPC sont successivement intégrées dans le processus de mapping, afin d’enrichir les possibilités de types de modèles en entrées de la transformation. Les machines B produites par la transformation permettent la preuve automatique intégrale par l’Atelier B. L’ensemble de ces travaux, chacun à leur niveau, contribuent à renforcer l’efficacité d’un cadre global d’analyse sécuritair

Shedding Light on the Complex Picture of Psychosocial Factors that Promote Mental Health in Young People

Across the world about half a billion people suffer from mental health problems each year. Most of such mental distress starts to manifest before or during adolescence. Childhood adversity (CA) is strongly associated with mental health problems. Resilience factors (RFs), such as self-esteem or social support, reduce mental health problems following CA. While a multitude of knowledge exists for single RFs, a more holistic understanding of the RF landscape is lacking. Such knowledge is however crucial, as we otherwise miss out on important interrelations between RFs (e.g. family support → self-esteem → friendships), and as a focus on single RFs may overestimate their importance and ecological validity. With my doctoral research I aimed to take on this challenge, by conducting six projects. I focused on emotional, social, behavioural, and cognitive factors, rather than on the underlying biological or higher-order cultural factors, to specifically study those RFs that can be directly targeted in psychosocial interventions. The first project is a preregistered systematic review with which I aimed to identify empirically supported RFs, on the individual-, family- and community-level. Building on the notion that examining single RFs may not be sufficient to understand the system that protects individuals from developing mental health problems, the second project was aimed at examining the interrelations of those 10 RFs that were identified in the systematic review and were assessed in our population-based adolescent cohort (N > 1K). With the third project I took the research question of how RFs are interconnected a step further and tried to unravel RF changes during the vulnerable period between early (age 14) and later adolescence (age 17). The fourth project was aimed at shedding light on the relative importance as well as on the predictive value with which RFs reduce subsequent mental health problems, as such knowledge may inform risk and mental-health screening. In the fifth project I explored how RFs mitigate the relationship between CA and subsequent mental health problems, by testing a series of direct-effect, moderation and mediation models. Such information may be vital as different effects may hold different implications for intervention research. The sixth and last project was aimed at investigating the most important RFs from the previous projects, high self-esteem and low brooding, in response to a natural stressor. More specifically, I studied those two RFs before, during and after a stress-inducing exam period in medical students, to find out whether the RFs change from before to after the stressor, and whether they co-evolve with mental distress (i.e. mutual change). My doctoral research revealed that RFs indeed cut across multiple ecological levels (i.e. individual, family and community level) and that every level has a notable impact on mental health. This clearly underpins the importance of more holistic RF research. Moreover, I showed that RFs can be described as a promotive system. The RFs seemed to enhance each other less in adolescents with a CA history, compared to adolescents without a CA history. This potential disadvantage of the RF system in adolescents with CA was only detected at age 14, more proximally after CA. However, most pathways between RFs and distress did not change from earlier to later adolescence, which indicates that some deleterious effects that are associated with CA do not seem to wane over the course of adolescence. Furthermore, I found that brooding (abstract, negative-focussed, and repetitive thinking) and self-esteem (quest for nurturing and optimizing self-worth) seem to be particularly promising transdiagnostic factors for risk and mental-health screening. Those RFs had the highest relative importance and predicted subsequent distress similarly well as distress could predict itself. Brooding and self-esteem were also among those RFs that best described the deleterious relationship between CA and subsequent mental health, and may therefore be fruitful targets for psycho-education as well as for psychosocial intervention research. Last but not least my research revealed that both high self-esteem and low brooding before exams mitigate increase in mental distress during the stress-inducing exams, suggesting that both have a potentially promising prevention effect. Moreover, self-esteem during exams fostered recovery of mental distress after exams, suggesting that self-esteem may also be a fruitful target for treatments at times of stress. Of course, all findings need replication in independent samples, and derived conjectures need to be tested in translational (intervention) studies. All in all, my doctoral research has not only enhanced the empirical understanding of the complex landscape of RFs, but has also shed light on potentially time-efficient and strength-based RF targets. Therefore, my findings offer valuable recommendations for public mental health and clinical intervention research.Medical Research Council, Pinsent Darwin, and Sackler Fundin