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Parameterschätzung und Modellevaluation für komplexe SystemeSchumann-Bischoff, Jan 06 April 2016 (has links)
No description available.
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Grinding mill circuit control from a plant-wide control perspectiveLe Roux, Johan Derik January 2016 (has links)
A generic plant-wide control structure is proposed for the optimal operation of a grinding mill circuit.
An economic objective function is defined for the grinding mill circuit with reference to the economic
objective of the larger mineral processing plant. A mineral processing plant in this study consists of a
comminution and a separation circuit and excludes the extractive metallurgy at a metal refinery. The
comminution circuit's operational performance primarily depends on the mill's performance. Since
grindcurves define the operational performance range of a mill, the grindcurves are used to define
the setpoints for the economic controlled variables for optimal steady-state operation. For a given
metal price, processing cost, and transportation cost, the proposed structure can be used to define
the optimal operating region of a grinding mill circuit for the best economic return of the mineral
processing plant. The plant-wide control structure identifies the controlled and manipulated variables
to ensure the grinding mill circuit can be maintained at the desired operating condition.
The plant-wide control framework specifies regulatory and supervisory control aims which can be
achieved by means of non-linear model-based control. An impediment to implementing model-based
control is the computational expense to solve the non-linear optimisation function. To resolve this
issue, the reference-command tracking version of model predictive static programming (MPSP) is
applied to a grinding mill circuit. MPSP is an innovative optimal control technique that combines
the philosophies of Model Predictive Control (MPC) and approximate dynamic programming. The
performance of the proposed MPSP control technique, is compared to the performance of a standard
non-linear MPC (NMPC) technique applied to the same plant for the same conditions. Results show
that the MPSP control technique is more than capable of tracking the desired set-point in the presence
of model-plant mismatch, disturbances and measurement noise. The performance of MPSP and NMPC
compare very well, with definite advantages offered by MPSP. The computational speed of MPSP
is increased through a sequence of innovations such as the conversion of the dynamic optimization
problem to a low-dimensional static optimization problem, the recursive computation of sensitivity
matrices, and using a closed form expression to update the control. The MPSP technique generally
takes only a couple of iterations to converge, even when input constraints are applied. Therefore,
MPSP can be regarded as a potential candidate for on-line applications of the NMPC philosophy to
real-world industrial process plants.
The MPSP and NMPC simulation studies above assume full-state feedback. However, this is not always
possible for industrial grinding mill circuits. Therefore, a non-linear observer model of a grinding mill
is developed which distinguishes between the volumetric hold-up of water, solids, and the grinding
media in the mill. Solids refer to all ore small enough to discharge through the end-discharge grate,
and grinding media refers to the rocks and steel balls. The rocks are all ore too large to discharge from
the mill. The observer model uses the accumulation rate of solids and the discharge rate as parameters.
It is shown that with mill discharge flow-rate, discharge density, and volumetric hold-up measurements,
the model states and parameters are linearly observable. Although instrumentation at the mill discharge
is not yet included in industrial circuits because of space restrictions, this study motivates the benefits
to be gained from including such instrumentation. An Extended Kalman Filter (EKF) is applied
in simulation to estimate the model states and parameters from data generated by a grinding mill
simulation model from literature. Results indicate that if sufficiently accurate measurements are
available, especially at the discharge of the mill, it is possible to reliably estimate grinding media,
solids and water hold-ups within the mill. Such an observer can be used as part of an advanced process
control strategy. / 'n Generiese aanlegwye beheerstruktuur vir die optimale beheer van 'n maalmeulkring word voorgehou.
'n Ekonomiese doelwitfunksie is gedefinieer vir die maalmeulkringbaan met verwysing tot die
ekonomiese doelwit van die groter mineraalverwerkingsaanleg. 'n Mineraalverwerkingsaanleg bestaan
in hierdie studie slegs uit die vergruisings- en skeidingskringbane. Die ekstraktiewe metallurgie by
die metaal raffinadery word uitgesluit. Die vergruisingskringbaan se operasionele werksverrigting is
hoofsaaklik van die maalmeul se werksverrigting afhanklik. Aangesien maalkurwes die bereik van
die maalmeul se werksverrigting beskryf, kan die maalkurwes gebruik word om die stelpunte van die
ekonomiese beheerveranderlikes te definieer vir werking by optimale gestadigde toestand. Gegewe
'n bepaalde metaalprys, bedryfskoste, en vervoerkoste, kan die voorgestelde struktuur gebruik word
om die optimale werksgebied vir die maalmeulkring te definieer vir die beste ekonomiese gewin van
die algehele mineraalverwerkingsaanleg. Die aanlegwye beheerstruktuur omskryf die beheerveranderlikes
en manipuleerbare veranderlikes wat benodig word om die maalmeulkring by die gewenste
werksgebied te handhaaf. Die aanlegwye beheerstruktuur spesifiseer regulatoriese en toesighoudende beheer doelwitte. Hierdie
doelwitte kan bereik word deur gebruik te maak van nie-lineêre model gebaseerde beheer. Die probleem
is dat die bewerkingskoste om nie-lineëre optimeringsfunksies op te los 'n struikelblok is om model
gebaseerde beheer op industriële aanlegte toe te pas. Ter oplossing hiervan, word die stelpunt-volg
weergawe van model gebaseerde voorspellende statiese programmering (MVSP) toegepas op 'n
maalmeulkringbaan. MVSP is 'n innoverende optimale beheertegniek, en bestaan uit 'n kombinasie
van die filosofieë van model gebaseerder voorspellende beheer (MVB) en aanpassende dinamiese
programmering. Die verrigting van die voorgestelde MVSP beheertegniek word vergelyk met die
verrigting van 'n standaard nie-lineëre MVB (NMVB) tegniek deur beide beheertegnieke op dieselfde
aanleg vir dieselfde toestande toe te pas. Resultate dui aan dat die MVSP beheertegniek in staat is
om die gekose stelpunt te midde van model-aanleg wanaanpassing, steurnisse, en metingsgeraas te
volg. Die verrigting van MVSP en NMVB vergelyk goed, maar MVSP bied duidelike voordele. Die
bewerkingspoed vir MVSP word vinniger gemaak deur die dinamiese optimeringsprobleem in 'n laeorde
statiese optimeringsprobleem te omskep, die sensitiwiteitsmatrikse rekursief uit te werk, en deur
'n geslote uitdrukking ter opdatering van die beheeraksie te gebruik. Die MVSP beheertegniek benodig
normaalweg slegs 'n paar iterasies om tot 'n oplossing te konvergeer, selfs indien beperkings op die
insette toegepas word. Om die rede word MVSP as 'n potensiële kandidaat beskou vir aanlyntoepasings
van die NMVB filosofie op industriële aanlegte.
Die MVSP en NMVB simulasie studies hierbo neem aan dat volle toestandterugvoer moontlik is.
Hierdie is nie altyd moontlik vir industriële maalmeulkringbane nie. Om die rede is 'n nie-lineêre
waarnemingsmodel van 'n maalmeul ontwikkel. Die model onderskei tussen die volumetriese hoeveelheid
water, vaste stowwe, en maalmedia in die meul. Vaste stowwe verwys na alle erts wat klein
genoeg is om deur die uitskeidingsif aan die ontslagpunt van die meul te vloei. Maalmedia verwys
na rotse en staalballe in die meul, met rotse wat te groot is om deur die uitskeidingsif te vloei. Die
waarnemingsmodel maak gebruik van die ontslaantempo en die opeenhopingstempo van vaste stowwe
as parameters. Indien die meul se ontslagvloeitempo, ontslagdigtheid, en totale volumetriese aanhouding
gemeet word, is alle toestande en parameters van die waarnemingsmodel lineêr waarneembaar.
Alhoewel instrumentasie by die meul se ontslagpunt as gevolg van ruimte beperkings nog nie op
industriële aanlegte ingesluit word nie, dui hierdie studie die voordele aan wat verkrygbaar is deur
sulke instrumentasie in te sluit. 'n Verlengde Kalman Filter (VKF) word in simulasie gebruik om
die model se toestande en parameters af te skat. 'n Bestaande maalmeul simulasie model vanuit die
literatuur word gebruik om die nodige data vir die VKF te genereer. Resultate dui aan dat indien die metings akkuraat genoeg is, veral by die ontslagpunt van die meul, betroubare afskattings van die
volumetriese hoeveelheid maalmedia, vaste stowwe, en water in die meul gemaak kan word. So 'n
afskatter kan vorentoe gebruik word as deel van 'n gevorderde prosesbeheer strategie. / Thesis (PhD)--University of Pretoria, 2016. / Electrical, Electronic and Computer Engineering / PhD / Unrestricted
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Development of an Intelligent Tire Based Tire - Vehicle State Estimator for Application to Global Chassis ControlSingh, Kanwar Bharat 27 January 2012 (has links)
The contact between the tire and the road is the key enabler of vehicle acceleration, deceleration and steering. However, under the circumstances of sudden changes to the road conditions, the driver`s ability to maintain control of the vehicle maybe at risk. In many cases, this requires intervention from the chassis control systems onboard the vehicle. Although these systems perform well in a variety of situations, their performance can be improved if a real-time estimate of the tire-road contact parameters (ranging from kinematic conditions of the tire to its dynamic properties) are available. At the present stage of development, tire-road contact parameters are indirectly estimated using observers based on vehicle dynamics measurements (acceleration, yaw and roll rates, suspension deflections, etc). Although these methods present a relatively accurate solution, they rely heavily on tire and vehicle kinematic formulations and break down in case of abrupt changes in the measured quantities.
To address this problem, researchers have been developing certain sensor based advanced tire concepts for direct measurement of the tire-road contact parameters. Thus the new terms "Intelligent Tire" and "Smart Tire", which mean online tire monitoring are thus enjoying increasing popularity among automotive manufacturers and formed the motivation for this thesis to explore the possibility of developing an intelligent tire system. The development of the so called "intelligent tire/ smart tire system" is expected to spur the development of a new generation of vehicle control system with modified control strategies, leveraging information directly coming from the interface between the tire and the road, and in turn significantly reducing the risk of accidents.
The specific contributions of this thesis include the following:
• Development of an intelligent tire system, with a special attention to development of measurement and sensor feature extraction methodologies of acceleration signals coming from sensors fixed to the tire innerliner
• Design of an integrated vehicle state estimator for application to global chassis control
• Development of a model-based tire-road friction estimation algorithm
• Development of an intelligent tire based adaptive wheel slip controller for anti-lock brake system (ABS)
• Development of a piezoelectric vibration energy harvesting system with an adaptive frequency tuning mechanism for intelligent tires / Master of Science
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Estimation d'état, estimation paramétrique et identifiabilité des modèles quasi-LPV / State and parameter estimation, and identi ability of quasi-LPV modelsSrinivasarengan, Krishnan 28 June 2018 (has links)
Dans cette thèse, deux problèmes liés aux approches basées sur des modèles pour le diagnostic de défauts et l'estimation du niveau de dégradation des équipements dans un bâtiment sont étudiés: la conception d'observateurs adaptatifs pour l'estimation de l'état et des paramètres, et l'analyse de l'identifiabilité des paramètres. La classe des modèles considérés est celle des modèles quasi-linéaires à paramètres variants dans le temps (quasi-LPV) avec paramétrisation affine des matrices d'état. Utilisant l'approche polytopique de Takagi-Sugeno (T-S), deux types d'observateurs sont proposés, un pour des systèmes en temps continu et l'autre pour des systèmes en temps discret. La structure de Luenberger (correction de la dynamique à l'aide de l'erreur d'estimation de la sortie) est choisie pour la partie d'estimation d'état de l'observateur pour les deux et leur conception s'appuie sur l'approche de Lyapunov. Pour la partie d'estimation des paramètres, une structure originale est proposée en temps continu et une structure proportionnelle-intégrale (PI) est utilisée en temps discret. La troisième contribution présente succinctement une méthode d'estimation d'état et des paramètres de façon découplée. Elle utilise conjointement l'approche de l'espace de parité et un observateur à mémoire finie. Pour la quatrième contribution relative à l'identifiabilité des paramètres, les états du système sont tout d'abord éliminés en utilisant une approche de type espace de parité. Cela permet d'extraire le `résumé exhaustif' du modèle qui aide à établir l'identifiabilité du modèle. Tous les résultats sont illustrés à l'aide d'exemples / Two problems relevant to the model-based approaches to fault diagnosis and degradation estimation in commissioned buildings are investigated in this thesis: adaptive observers for state and parameter estimation, and parameter identifiability. The system models considered are the quasi-LPV models with affine parameterization. Using the Takagi-Sugeno (T-S) polytopic approach, two observer designs, one for continuous-time models and another for discrete-time models are provided. Both models use a Luenberger structure for the state estimation part and deploy the Lyapunov design approach. An innovative non-linear estimation model is obtained through the design process for the continuous-time parameter estimation whereas a proportional-integral (PI) structure is used for discrete-time. A brief third contribution is a decoupled state and parameter estimation that makes use of the parity-space approach and realized using a finite memory observer strategy. For the fourth contribution of parameter identifiability, a parity-space formulation using null-space computation is used for the elimination of states of the model from which the exhaustive summary of the model is extracted and the identifiability of the model verified. All the results are illustrated using examples
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Information Field Theory Approach to Uncertainty Quantification for Differential Equations: Theory, Algorithms and ApplicationsKairui Hao (8780762) 24 April 2024 (has links)
<p dir="ltr">Uncertainty quantification is a science and engineering subject that aims to quantify and analyze the uncertainty arising from mathematical models, simulations, and measurement data. An uncertainty quantification analysis usually consists of conducting experiments to collect data, creating and calibrating mathematical models, predicting through numerical simulation, making decisions using predictive results, and comparing the model prediction with new experimental data.</p><p dir="ltr">The overarching goal of uncertainty quantification is to determine how likely some quantities in this analysis are if some other information is not exactly known and ultimately facilitate decision-making. This dissertation delivers a complete package, including theory, algorithms, and applications of information field theory, a Bayesian uncertainty quantification tool that leverages the state-of-the-art machine learning framework to accelerate solving the classical uncertainty quantification problems specified by differential equations.</p>
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Commande tolérante aux défauts des systèmes non linéaires représentés par des modèles de Takagi-Sugeno / Fault tolerant control for Takagi-Sugeno nonlinear systemsBezzaoucha, Souad 25 October 2013 (has links)
Cette thèse porte sur la représentation T-S des systèmes non linéaires et les non-linéarités qui leur sont associées (saturation et paramètres variants dans le temps) pour la commande et le diagnostic. Ainsi, une nouvelle approche utilisant la transformation par secteurs non linéaires permet de ré-écrire le système sous forme polytopique en prenant en compte la présence de paramètres variants dans le temps. Cette forme polytopique est ensuite utile pour la synthèse d'observateurs assurant l'estimation simultanée de l'état et des paramètres du système. Une application au diagnostic est également considérée en comparant les valeurs des paramètres estimés en ligne avec leurs valeurs nominales supposées connues et représentatives du mode de fonctionnement non défaillant. Concernant la commande, la contrainte de saturation est représentée sous forme de modèle T-S et est intégrée au modèle du système. La synthèse de plusieurs lois de commande assurant la stabilité du système bouclé, en prenant en compte les limites de saturation est proposée. La poursuite de modèle de référence est également traitée avec la mise en évidence des conditions structurelles de poursuite pour les modèles non linéaires sous forme T-S. L'accent est mis sur les différents critères de choix de commande en fonction des buts recherchés / A first contribution of this thesis is to propose a systematic procedure to deal with the state and parameter estimation for nonlinear time-varying systems. It consists in transforming the original system into a T-S model with unmeasurable premise variables using the sector nonlinearity transformation. Then a joint state and parameter observer is designed and the convergence conditions of the joint state and parameter estimation errors are established. The second contribution of this thesis is the stabilization problem under saturation constraints. In fact, we aim to present a new approach for the saturation nonlinearity study, where the sector nonlinearity transformation is used to represent the nonlinear behaviour of a saturated actuator under a T-S form. The T-S representation of the saturation is used to integrate the limitation constraints into the control synthesis, such that the system stability is ensured and the controller gains are calculated according to the saturation level. The model reference tracking control problem is also addressed. It aims to highlight the encoutered difficulties and the proposed solutions to achieve the tracking objective. Through analytical studies, by presenting clear structural conditions and control strategies, we try to point and answer some major interogations, that are : "how the model reference is to be chosen ? " and "which tracking criterion to consider to achieve a certain objective ? ". The case of constrained control input is also considered with a special focus on the anticipation for the saturated control
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Observer-based engine air charge characterisation : rapid, observer-assisted engine air charge characterisation using a dynamic dual-ramp testing methodSchaal, Peter January 2018 (has links)
Characterisation of modern complex powertrains is a time consuming and expensive process. Little effort has been made to improve the efficiency of testing methodologies used to obtain data for this purpose. Steady-state engine testing is still regarded as the golden standard, where approximately 90% of testing time is wasted waiting for the engine to stabilize. Rapid dynamic engine testing, as a replacement for the conventional steady-state method, has the potential to significantly reduce the time required for characterisation. However, even by using state of the art measurement equipment, dynamic engine testing introduces the problem that certain variables are not directly measurable due to the excitation of the system dynamics. Consequently, it is necessary to develop methods that allow the observation of not directly measurable quantities during transient engine testing. Engine testing for the characterisation of the engine air-path is specifically affected by this problem since the air mass flow entering the cylinder is not directly measurable by any sensor during transient operation. This dissertation presents a comprehensive methodology for engine air charge characterisation using dynamic test data. An observer is developed, which allows observation of the actual air mass flow into the engine during transient operation. The observer is integrated into a dual-ramp testing procedure, which allows the elimination of unaccounted dynamic effects by averaging over the resulting hysteresis. A simulation study on a 1-D gas dynamic engine model investigates the accuracy of the developed methodology. The simulation results show a trade-off between time saving and accuracy. Experimental test result confirm a time saving of 95% compared to conventional steady-state testing and at least 65% compared to quasi steady-state testing while maintaining the accuracy and repeatability of conventional steady-state testing.
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