Дисертації з теми "Off line Model Predictive Control"
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Filippo, Marco. "Stabilizing nonlinear model predictive control in presence of disturbances and off - line approximations of the control law." Doctoral thesis, Università degli studi di Trieste, 2011. http://hdl.handle.net/10077/4519.
Повний текст джерелаOne of the more recent and promising approaches to control is the Receding Horizon one. Due to its intrinsic characteristics, this methodology, also know as Model Predictive Control, allows to easily face disturbances and model uncertainties: indeed at each sampling instant the control action is recalculated on the basis of the reached state (closed loop). More in detail, the procedure consists in the minimization of an adequate cost function with respect to a control input sequence; then the first element of the optimal sequence is applied. The whole procedure is then continuously reiterated. In this thesis, we will focus in particular on robust control of constrained systems. This is motivated by the fact that, in practice, every real system is subjected to uncertainties, disturbances and constraints, in particular on state and input (for instance, plants can work without being damaged only in a limited set of configurations and, on the other side, control actions must be compatible with actuators' physical limits). With regard to the first aspect, maintaining the closed loop stability even in presence of disturbances or model mismatches can result in an essential strategy: moreover it can be exploited in order to design an approximate stabilizing controller, as it will be shown. The control input values are obtained recurring to a Nearest Neighbour technique or, in more favourable cases, to a Neural Network based approach to the exact RH law, which can be then calculated off line: this implies a strong improvement related to the applicability of MPC policy in particular in terms of on line computational burden. The proposed scheme is capable to guarantee stability even for systems that are not stabilizable by means of a continuous feedback control law. Another interesting framework in which the study of the influence of uncertainties on stability can lead to significant contributions is the networked MPC one. In this case, due to the absence of physical interconnections between the controller and the systems to be controlled, stability can be obtained only taking into account of the presence of disturbances, delays and data losses: indeed this kind of uncertainties are anything but infrequent in a communication network. The analysis carried out in this thesis regards interconnected systems and leads to two distinct procedures, respectively stabilizing the linear systems with TCP protocol and nonlinear systems with non-acknowledged protocol. The core of both the schemes resides in the online solution of an adequate reduced horizon optimal control problem.
Una delle strategie di controllo emerse più recentemente, più promettenti e di conseguenza più studiate negli ultimi anni è quella basata sull'approccio Receding Horizon. Grazie alle caratteristiche che contraddistinguono questa tecnica, cui si fa spesso riferimento anche col nome di Model Predictive Control, risulta piuttosto agevole trattare eventuali disturbi e incertezze di modellazione; tale metodo prevede infatti il calcolo di un nuovo ingresso di controllo per ciascun istante di campionamento, in seguito alla minimizzazione ad ogni passo di un'opportuna funzione di costo rispetto ad una sequenza di possibili futuri ingressi, inizializzata sulla base del valore dello stato del sistema all'istante considerato. Il controllo è dato dal primo elemento di tale sequenza ottima; tutto questo viene continuamente ripetuto, il che comporta un aggiornamento costante del segnale di controllo. Gli inconvenienti di questa tecnica risiedono nelle elevate risorse computazionali e nei tempi di calcolo richiesti, così da ridurne drasticamente l'applicabilità specie nel caso di sistemi con elevata dinamica. In questa tesi ci si concentrerà sulle caratteristiche di robustezza del controllore: l'importanza di quest'analisi risiede nel fatto che ogni sistema reale è soggetto a incertezze e disturbi di varia origine cui bisogna far fronte durante le normali condizioni di funzionamento. Inoltre, la capacità di gestire errori di modellazione, come si vedrà, può essere sfruttata per ottenere un notevole incremento delle prestazioni nella stima del valore da fornire in ingresso all'impianto: si tratta di ripartire l'errore complessivo in modo da garantirsi dei margini che consentano di lavorare con un'approssimazione della legge di controllo, come specificato più avanti. In tutto il lavoro si considereranno sistemi vincolati: l'interesse per questa caratteristica dipende dal fatto che nella pratica vanno sempre tenuti in considerazione eventuali vincoli su stato e ingressi: basti pensare al fatto che ogni impianto è progettato per lavorare solo all'interno un determinato insieme di configurazioni, determinato ad esempio da vincoli fisici su attuatori, sensori e così via: non riporre sufficiente attenzione in tali restrizioni può risultare nel danneggiamento del sistema di controllo o dell'impianto stesso. Le caratteristiche di stabilità di un sistema controllato mediante MPC dipendono in modo determinante dalla scelta dei parametri e degli attributi della funzione di costo da minimizzare; nel seguito, con riferimento al caso dei sistemi non lineari, saranno forniti suggerimenti e strumenti utili in tal senso, al fine di ottenere la stabilità anche in presenza di disturbi (che si assumeranno opportunamente limitati). Successivamente tale robustezza verrà sfruttata per la progettazione di controllori stabilizzanti approssimati: si dimostrerà infatti che, una volta progettato adeguatamente il sistema di controllo “esatto” basato su approccio RH e conseguentemente calcolati off-line i valori ottimi degli ingressi su una griglia opportunamente costruita sul dominio dello stato, il ricorso a una conveniente approssimazione di tali valori non compromette le proprietà di stabilità del sistema complessivo, che continua per di più a mantenere una certa robustezza. Da notare che ciò vale anche per sistemi non stabilizzabili mediante legge di controllo feedback continua: la funzione approssimante può essere ottenuta in questo caso con tecniche di tipo Nearest Neighbour; qualora invece la legge di controllo sia sufficientemente regolare si potrà far ricorso ad approssimatori smooth, quali ad esempio le reti neurali. Tutto ciò comporta un notevole miglioramento delle prestazioni del controllore RH sia dal punto di vista del tempo di calcolo richiesto che (nel secondo caso) della memoria necessaria ad immagazzinare i parametri del controllore, risultando nell'applicabilità dell'approccio basato su MPC anche al caso di sistemi con elevata dinamica. Un altro ambito in cui lo studio dell'influenza delle incertezze e dei disturbi sulla stabilità richiede una notevole attenzione è quello dei sistemi networked; anche in questo caso il ricorso all'MPC può portare a ottimi risultati di stabilità robusta, a patto di individuare un' opportuna struttura per il sistema complessivo ed effettuare scelte adeguate per il problema di ottimizzazione. In particolare, si considererà il caso di trasmissione di dati tra un controllore centralizzato e le varie parti dell'impianto in assenza di collegamento fisico diretto. Lo studio della stabilità dovrà allora tenere in considerazione la presenza di perdite di pacchetti o ritardi di trasmissione, condizioni tutt'altro che infrequenti per le reti. Saranno quindi proposte due distinte procedure, che si dimostreranno essere in grado di garantire robustezza a sistemi rispettivamente lineari comunicanti con protocolli di tipo TCP e non lineari in presenza di protocolli UDP. Questo secondo caso è senz'altro il più complesso ma allo stesso tempo il più concreto tra i due. Il nucleo del controllo è ancora basato su una tecnica MPC, ma stavolta il controllore è chiamato a risolvere il problema di ottimizzazione su un orizzonte “ridotto”, che consente la gestione dei ritardi e di eventuali perdite di pacchetto su determinati canali. La lunghezza dell'orizzonte dipenderà dalla presenza o meno dei segnali di ricezione del pacchetto (acknowledgement).
XXIII Ciclo
1977
Pin, Gilberto. "Robust nonlinear receding horizon control with constraint tightening: off line approximation and application to networked control system." Doctoral thesis, Università degli studi di Trieste, 2009. http://hdl.handle.net/10077/3122.
Повний текст джерелаNonlinear Receding Horizon (RH) control, also known as moving horizon control or nonlinear Model Predictive Control (MPC), refers to a class of algorithms that make explicit use of a nonlinear process model to optimize the plant behavior, by computing a sequence of future ma- nipulated variable adjustments. Usually the optimal control sequence is obtained by minimizing a multi-stage cost functional on the basis of open-loop predictions. The presence of uncertainty in the model used for the optimization raises the question of robustness, i.e., the maintenance of certain properties such as stability and performance in the presence of uncertainty. The need for guaranteeing the closed-loop stability in presence of uncertainties motivates the conception of robust nonlinear MPC, in which the perturbations are explicitly taken in account in the design of the controller. When the nature of the uncertainty is know, and it is assumed to be bounded in some compact set, the robust RH control can be determined, in a natural way, by solving a min–max optimal control problem, that is, the performance objective is optimized for the worst-case scenario. However, the use of min-max techniques is limited by the high computational burden required to solve the optimization problem. In the case of constrained system, a possibility to ensure the robust constraint satisfaction and the closed-loop stability without resorting to min-max optimization consists in imposing restricted (tightened) constraints on the the predicted trajectories during the optimization. In this framework, an MPC scheme with constraint tightening for discrete-time nonlinear systems affected by state-dependent and norm bounded uncertainties is proposed and discussed. A novel method to tighten the constraints relying on the nominal state prediction is described, leading to less conservative set contractions than in the existing approaches. Moreover, by imposing a stabilizing state constraint at the end of the control horizon (in place of the usual terminal one placed at the end of the prediction horizon), less stringent assumptions can be posed on the terminal region, while improving the robust stability properties of the MPC closed-loop system. The robust nonlinear MPC formulation with tightened constraints is then used to design off- line approximate feedback laws able to guarantee the practical stability of the closed-loop system. By using off-line approximations, the computational burden due to the on-line optimization is removed, thus allowing for the application of the MPC to systems with fast dynamics. In this framework, we will also address the problem of approximating possibly discontinuous feedback functions, thus overcoming the limitation of existent approximation scheme which assume the continuity of the RH control law (whereas this condition is not always verified in practice, due to both nonlinearities and constraints). Finally, the problem of stabilizing constrained systems with networked unreliable (and de- layed) feedback and command channels is also considered. In order to satisfy the control ob- jectives for this class of systems, also referenced to as Networked Control Systems (NCS’s), a control scheme based on the combined use of constraint tightening MPC with a delay compen- sation strategy will be proposed and analyzed. The stability properties of all the aforementioned MPC schemes are characterized by using the regional Input-to-State Stability (ISS) tool. The ISS approach allows to analyze the depen- dence of state trajectories of nonlinear systems on the magnitude of inputs, which can represent control variables or disturbances. Typically, in MPC the ISS property is characterized in terms of Lyapunov functions, both for historical and practical reasons, since the optimal finite horizon cost of the optimization problem can be easily used for this task. Note that, in order to study the ISS property of MPC closed-loop systems, global results are in general not useful because, due to the presence of state and input constraints, it is impossible to establish global bounds for the multi-stage cost used as Lyapunov function. On the other hand local results do not allow to analyze the properties of the predictive control law in terms of its region of attraction. There- fore, regional ISS results have to employed for MPC controlled systems. Moreover, in the case of NCS, the resulting control strategy yields to a time-varying closed-loop system, whose stability properties can be analyzed using a novel regional ISS characterization in terms of time-varying Lyapunov functions.
XXI Ciclo
1980
Peenze, Andries Jacobus. "Model predictive suspension control on off-road vechicles." Diss., University of Pretoria, 2019. http://hdl.handle.net/2263/79302.
Повний текст джерелаDissertation (MEng)--University of Pretoria, 2019.
Mechanical and Aeronautical Engineering
MEng
Unrestricted
Annamalai, Andy S. K. "An adaptive autopilot design for an uninhabited surface vehicle." Thesis, University of Plymouth, 2014. http://hdl.handle.net/10026.1/3100.
Повний текст джерелаVettorazzo, Carolina Maia. "Model predictive control of gas compression station in off-shore production platforms." reponame:Repositório Institucional da UFSC, 2016. https://repositorio.ufsc.br/xmlui/handle/123456789/179945.
Повний текст джерелаMade available in DSpace on 2017-10-10T04:09:13Z (GMT). No. of bitstreams: 1 348412.pdf: 1522637 bytes, checksum: bfc8477785a30cc5de8726097fb056f2 (MD5) Previous issue date: 2016
Uma plataforma off-shore normalmente produz petróleo bruto e gás natural. O gás é tratado para a remoção da humidade e sua pressão e sua temperatura são modificadas de acordo com sua aplicação final. Parte do gás é direcionado para a linha de exportação de gás para ser comercializado. Muitas vezes o gás é utilizado por poços que operam com elevação por gaslift. O gás natural também é usado em turbinas para gerar eletricidade. Um sistema de compressão de gás é uma parte importante de uma unidade de produção off-shore de petróleo. O tipo de compressor mais usado em um sistema de compressão de gás é o compressor centrífugo. Uma falha do compressor pode fazer com que uma unidade de produção completa seja desligada. Os compressores centrífugos têm limites operacionais muito restritos e são muito sensíveis a mudanças na vazão de entrada de gás ou nas propriedades do mesmo. O compressor pode entrar em surge, que é uma condição operacional instável caracterizada pelo fluxo reverso de gás dentro do compressor e que pode acontecer quando a vazão de entrada de gás é muito baixa. Um compressor centrífugo que opera em surge não comprimirá o gás corretamente, causando danos permanentes à máquina. O procedimento normal utilizado quando se detecta a ocorrência de surge é parar o compressor. Geralmente, os compressores centrífugos são instalados com um controle regulatório que inclui a prevenção de surge. No entanto, mudanças bruscas na vazão de entrada de gás e na composição do gás são conhecidas por fazer com que o compressor centrífugo pare com frequência. Esta dissertação propõe um controlador MPC que reduz o consumo de energia do sistema de compressão e melhora sua proteção contra surge. Este trabalho também apresenta a modelagem de uma estação de compressão real composta de dois compressores de três estágios. Com base na análise do comportamento do sistema e da relação dinâmica entre as entradas e saídas do sistema, são propostas e testadas duas formulações de MPC diferentes. Para ajustar o controlador MPC foi aplicada a técnica de ajuste satisfatório, melhorando o desempenho do controlador.
Abstract : An offshore oil production unit normally produces crude oil and natural gas. The gas is treated for removal of moisture and its pressure and temperature are conditioned to its target application. Part of the gas is directed to the gas export line for sales. Often it is used by wells operating with gas lift. Natural gas is also used in turbines to generate electricity. A gas compression system is an important part of an offshore oil production unit. The most important type of equipment used in a gas compression system is the centrifugal compressor. A compressor failure may cause a complete production unit shut down. Centrifugal compressors have a limited operational range and are very sensitive to changes in the gas flow rate or in its properties. Compressor surge is an unstable operational condition characterized by reverse flow inside the compressor and it can happen when the gas flow rate is too low. A centrifugal compressor operating in surge mode will not compress the gas as required and the machine could be damaged permanently. The normal procedure used when surge is detected is to stop the compressor. Usually centrifugal compressors are installed with a regulatory control that includes the avoidance of surge. But abrupt changes in gas flowrate and gas composition are known to cause centrifugal compressor to stop the production operations too often. This dissertation proposes a MPC controller that reduces the energy consumption of the compression system and improves its protection against surge. This work also presents the modeling of a real compression station composed of two three-stage compressors. Based on the analysis of the system?s behavior and the dynamic relation between inputs and outputs, two different MPC formulations are proposed and tested. To tune the MPC controller the satisficing tuning technique is applied, improving the controller?s performance.
NARDINI, ALBERTO. "Development of a thermomechanical and metallurgical model in order to design a predictive control tool in line." Doctoral thesis, Università Politecnica delle Marche, 2018. http://hdl.handle.net/11566/257295.
Повний текст джерелаAlaya, Oussama, and Maik Fiedler. "Optimal pressure control using switching solenoid valves." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-200545.
Повний текст джерелаBraconnier, Jean-Baptiste. "Maintien de l'intégrité de robots mobiles en milieux naturels." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22667/document.
Повний текст джерелаThis thesis focused on the issue of the preseving of the integrity of mobile robots in off-road conditions. The objective is to provide control laws to guarantee the integrity of a vehicle during autonomous displacements in natural environments at high speed (5 to 7 m.s -1 ) and more particularly in The framework of precision farming. Integrity is here understood in the broad sense. Indeed, control of the movements of a mobile robot can generate orders that affect its physical integrity, or restrains the achievement of its task (rollover, spin, control stability, maintaining accuracy , etc.). Moreover, displacement in natural environments leads to problems linked in particular to relatively variable and relatively low adhesion conditions (especially since the speed of the vehicle is high), which results in strong sliding of wheels on the ground, or to ground geometries that can not be crossed by the robot. This thesis aims to determine in real time the stability space in terms of permissible controls allowing to moderate the actions of the robot. After a presentation of the existing modelings and observers that allow the use of these modelizations for the implementation of predictive control law for trajectory tracking, a new method of estimation of side-slip angles based on a kinematic observation is proposed. It permit to address the problem of variable speed of the vehicle (and in particular the case of zero values) and also to allow the observation during a displacement without reference trajectory. This new observer is essential for the further development of this thesis, since the rest of the work is concerned with the modulation of the speed of the vehicle. So, in the further work, two predictive control laws acting on the speed of the vehicle have been set up. The first one provides a solution to the problem of the saturation of steering actuators, when the speed or side-slip angles make the trajectory inadmissible to follow with respect to the physical capacities of the vehicle. The second one adress the problem of guaranteeing the accuracy of trajectory tracking (keeping the vehicle in a corridor of displacement). In both cases, the control strategy is similar: the future state of the vehicle is predicted according to the current conditions of evolution and the simulated one for the future evolution (obtained by simulating the evolution of dynamics models of the vehicle) in order to determine the value of the optimum speed so that the target variables (in one case the value of the steering and in the other the lateral deviation from the trajectory) comply with the imposed conditions (not exceeding a target value). The results presented in this thesis were realized either in simulations or in real conditions on robotic platforms. It follows that the proposed algorithms make it possible : in one case to reduce the speed of the vehicle in order to avoid the saturation of the steering actuator and therefore the resulting over and under steering phenomena and thus make it possible to preserve the vehicle’s controllability. And in the other case, to ensure that the lateral deviation from the trajectory remains below a target value
Guillet, Audrey. "Commande locale décentralisée de robots mobiles en formation en milieu naturel." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22609/document.
Повний текст джерелаThis thesis focuses on the issue of the control of a formation of wheeled mobile robots travelling in off-road conditions. The goal of the application is to follow a reference trajectory (entirely or partially) known beforehand. Each robot of the fleet has to track this trajectory while coordinating its motion with the other robots in order to maintain a formation described as a set of desired distances between vehicles. The off-road context has to be considered thoroughly as it creates perturbations in the motion of the robots. The contact of the tire on an irregular and slippery ground induces significant slipping and skidding. These phenomena are hardly measurable with direct sensors, therefore an observer is set up in order to get an estimation of their value. The skidding effect is included in the evolution of each robot as a side-slip angle, thus creating an extended kinematic model of evolution. From this model, adaptive control laws on steering angle and velocity for each robot are designed independently. These permit to control respectively the lateral distance to the trajectory and the curvilinear interdistance of the robot to a target. Predictive control techniques lead then to extend these control laws in order to account for the actuators behavior so that positioning errors due to the delay of the robot response to the commands are cancelled. The elementary control law on the velocity control ensures an accurate longitudinal positioning of a robot with respect to a target. It serves as a base for a global fleet control strategy which declines the overall formation maintaining goal in local positioning objective for each robot. A bidirectionnal control strategy is designed, in which each robot defines 2 targets, the immediate preceding and following robot in the fleet. The velocity control of a robot is finally defined as a linear combination of the two velocity commands obtained by the elementary control law for each target. The linear combination parameters are investigated, first defining constant parameters for which the stability of the formation is proved through Lyapunov techniques, then considering the effect of variable coefficients in order to adapt in real time the overall behavior of the formation. The formation configuration can indeed be prone to evolve, for application purposes and to guarantee the security of the robots. To fulfill this latter requirement, each robot of the fleet estimates in real time a minimal stopping distance in case of emergency and two avoidance trajectories to get around the preceding vehicle if this one suddenly stops. Given the initial configuration of the formation and the emergency behaviors calculated, the desired distances between the robots can be adapted so that the new configuration thus described ensures the security of each and every robot of the formation against potential collisions
Qian, Jun. "Identification paramétrique en boucle fermée par une commande optimale basée sur l’analyse d’observabilité." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10113/document.
Повний текст джерелаFor online parameter identification, the developed methods here allow to design online and in closed loop optimal inputs that enrich the information in the current experience. These methods are based on real-time measurements of the process, on a dynamic nonlinear (or linear) multi-variable model, on a sensitivity model of measurements with respect to the parameters to be estimated and a nonlinear observer. Analysis of observability and predictive control techniques are used to define the optimal control which is determined online by constrained optimization. Stabilization aspects are also studied (by adding fictitious constraints or by a Lyapunov technique). Finally, for the particular case of a first order linear system, the explicit control law is developed. Illustrative examples are processed via the ODOE4OPE software : a bio-reactor, a continuous stirred tank reactor and a delta wing. These examples help to see that the parameter estimation can be performed with good accuracy in a single and less costly experiment
HAJHOUJ, MOUAMD. "Programmation hors ligne : emulation des composants d'une cellule robotisee." Paris, ENSAM, 1988. http://www.theses.fr/1988ENAM0005.
Повний текст джерелаAdolfssson, Alexander, and Marie Åström. "Development Finance Institutions’ Effect on The Fund Manager’s Investment Decisions : Balancing Financial Performance Goals and Development Impact Objectives." Thesis, Umeå universitet, Företagsekonomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-124744.
Повний текст джерелаNaidoo, Yubanthren Tyrin. "Practical on-line model validation for model predictive controllers (MPC)." Thesis, 2010. http://hdl.handle.net/10413/5706.
Повний текст джерелаThesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.
Ding-HueiLiang and 梁定輝. "Observer/Kalman Filter Identification Method and Model Predictive Control Approach-Based On-Line Fault-Tolerant Control." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/ca2ce8.
Повний текст джерела國立成功大學
電機工程學系
104
In this thesis, inputs are not allowed to be negative for some physical systems, so we propose improved on-line observer/Kalman filter identification (OKID) method for unknown stochastic systems. Besides, we use the model predictive control tracker for unknown system. It satisfies input constraint and fault-Tolerant.
Lee, Tsung-en, and 李聰恩. "Realization of Model Predictive Control of Coating Mass Weight Measured by Neural Network in Continuous Galvanization Line." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/32224783212564200397.
Повний текст джерела國立高雄第一科技大學
系統資訊與控制研究所
99
In the Continuous Galvanization Line(CGL),variation in the coating mass of strip will cause the serious defect of product, this thesis focuses on the optimal coating mass measurement for the moving strip by Neural Network and then designs an intelligent controller to carry out nozzle adjust by manual based on Model Predict Control theory, in order to improve the accuracy of coating mass and reduce production cost. The total process belongs to off-line simulation, Including coating mass measurement by MATLAB NNTOOL, and the MPC controller for the nozzle air pressure output by MATLAB Simulink. We adopt the actual on-line x-ray intensity value and coating mass data by the negression method and NNTOOL, and compare the result each other.As the accuracy is concerned, the latter is prefer to the former. And then, this paper brings up an essential model predictive control and monitoring system for coating mass weight control system in the Continuous Galvanization Line(CGL), The aim is eager to reduce operational costs and increasing process stability. From the simulation result, more than ninety percents of coating mass weight can come into being actural, and the air nozzle can be controlled under a reasonable range.