Dissertations / Theses on the topic 'Delay-based control'

Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 43-46).
This thesis introduces Copa, an end-to-end congestion control algorithm that uses three ideas. First, it shows that a target rate equal to 1/([delta]d[subscript q]), where d[subscript q] is the (measured) queueing delay, optimizes a natural function of throughput and delay under a Markovian packet arrival model. Second, it adjusts its congestion window in the direction of this target rate, converging quickly to the correct fair rates even in the face of significant flow churn. These two ideas enable a group of Copa flows to maintain high utilization with low queuing delay. However, when the bottleneck is shared with loss-based congestion-controlled flows that fill up buffers, Copa, like other delay-sensitive schemes, achieves low throughput. To combat this problem, Copa uses a third idea: detect the presence of buffer-fillers by observing the delay evolution, and respond with additive-increase/multiplicative decrease on the [delta] parameter. Experimental results show that Copa outperforms Cubic (similar throughput, much lower delay, fairer with diverse RTTs), BBR and PCC (significantly fairer, lower delay), and co-exists well with Cubic unlike BBR and PCC. Copa is also robust to non-congestive loss and large bottleneck buffers, and outperforms other schemes on long-RTT paths.
by Venkat Arun.
S.M.
S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

We investigate the issues in making a delay-based protocol adaptive to heterogeneous environments. We assess and address the problems a delay-based protocol faces when competing with a loss-based protocol such as TCP. We investigate if noise and variability in delay measurements in environments such as cable and ADSL access networks impact the delay-based protocol behavior significantly. We investigate these issues in the context of incremental deployment of a new delay-based protocol, PERT. We propose design modifications to PERT to compete with the TCP flavor SACK. We show through simulations and real network experiments that, with the proposed changes, PERT experiences lower drop rates than SACK and leads to lower overall drop rates with different mixes of PERT and SACK protocols. Delay-based protocols, being less aggressive, have problems in fully utilizing a highspeed link while operating alone. We show that a single PERT flow can fully utilize a high-speed, high-delay link. We performed several experiments with diverse parameters and simulated numerous scenarios using ns-2. The results from simulations indicate that PERT can adapt to heterogeneous networks and can operate well in an environment of heterogeneous protocols and other miscellaneous scenarios like wireless networks (in the presence of channel errors). We also show that proposed changes retain the desirable properties of PERT such as low loss rates and fairness when operating alone. To see how the protocol performs with the real-world traffic, the protocol has also been implemented in the Linux kernel and tested through experiments on live networks, by measuring the throughput and losses between nodes in our lab at TAMU and different machines at diverse location across the globe on the planet-lab. The results from simulations indicate that PERT can compete with TCP in diverse environments and provides benefits as it is incrementally deployed. Results from real-network experiments strengthen this claim as PERT shows similar behavior with the real-world traffic.

Cette thèse étudie l'utilisation de contrôleurs basés sur le retard pour les systèmes dynamiques. Quelques applications, quelques expériences, ainsi que des problèmes et des solutions théoriques sont abordés. L'accent principal de l'étude est mis sur la conception de contrôleurs basés sur le retard inspirés des contrôleurs PID. Plus précisément, nous développons des méthodes pour trouver le bon choix des paramètres du contrôleur assurant la stabilité pour différents types de contrôleurs. À cette fin, la thèse embrasse l'utilisation de modèles et d'analyses différentielles linéaires en raison de son élégante interprétation basée sur la fréquence. À cet égard, les propriétés de stabilité de ces systèmes sont régies par leur équation caractéristique, qui pour les systèmes à retards sont des quasi-polynômes. Ainsi, cette thèse étudie le comportement des racines de ces fonctions par rapport aux variations de leurs paramètres (coefficients du système et valeurs de retard) à travers des racines bien connues croisant la stabilité. Des méthodes numériques et des observations analytiques sont développées dans ce sens. En particulier, nous étudions les applications, les convertisseurs cc/cc, le pendule de Furuta, les dispositifs haptiques, et le problème MPPT-PV (maximum power point tracking - photovoltaic). Grâce à l'utilisation des régulateurs proportionnel-retard, proportionnel- dérivé basé sur retard, proportionnel-intégral retardé et proportionnel-retard-intégral. Nous proposons également une solution au problème classique de contrôle basé sur le retard, qui consiste à stabiliser une chaîne d'un nombre quelconque d'oscillateurs en appliquant un seul bloc de retard
This thesis studies the use of delay-based controllers for dynamical systems. Applications, experimentation, and theoretical problematics are addressed. The main focus of the study is the conception of delay-based controllers inspired by the well-known PID controllers. Also, and equally important, we study the design of such controllers. More precisely, we develop methods to find the proper choice of the controller's parameters assuring stability for different types of controllers. To this end, the thesis embraces the use of linear differential models and analysis due to its elegant frequency-based interpretation. In this regard, the stability properties of these systems are governed by their characteristic equation, which for time-delay systems are the so-called quasi-polynomials or polynomials with constant coefficients. Thus, this thesis studies the behavior of the roots of these functions with respect to variations of their parameters (coefficients and time delay values) through well-known roots crossing stability. Numeric methods and analytical observations are developed in this sense. In particular, we study applications, dc/dc converters, the Furuta pendulum, haptic devices, and the MPPT-PV (maximum power point tracking - photovoltaic) problem. Through the use of the proportional-delayed, proportional-delay-based derivative, proportional-delayed integral, and proportional-delayed-integral controllers. Also, we propose a solution to the classical delay-based control problem of stabilizing a chain of any number of oscillators by applying a single delay block

Le retard est un phénomène largement présent dans les systèmes de commande(i.e.retard physique, latence de communication, temps de calcul) et peut en dégrader les performances ou même les déstabiliser. Si le retard est faible, la stabilité en boucle fermée peut être garantie par des lois de commande conventionnelles mais ces techniques ne sont plus efficaces si le retard est long. Cette thèse est dédiée à la commande des systèmes à retard avec retards longs inconnus ou avec des retards incertains. Pour compenser les retards longs, la commande prédictive est adoptée et des techniques d’estimation de retard sont développées. Selon les différents types de systèmes et de retards, trois objectifs sont visés dans la thèse. Le premier objectif considère la commande des systèmes linéaires avec retards constants inconnus pour lesquels un nouvel estimateur de retard est proposé pour estimer les retards inconnus. Le retard estimé est ensuite utilisé dans la commande prédictive pour stabiliser le système. Le deuxième objectif se concentre sur la stabilisation pratique des systèmes commandés à distance avec des retards inconnus variants. Dans ce cas, les retards sont estimés de manière pratique : une boucle de communication spécifique est utilisée pour estimer le retard en temps fini puis le système est stabilisé par une commande prédictive. Les tests expérimentaux réalisés sur un réseau WiFi ont montré que l’algorithme permet d’estimer de manière robuste les retards variants. Le dernier objectif est consacré à la commande des systèmes commandés en réseau avec retards variants. La commande prédictive discrète est utilisée pour compenser les retards longs et variants et les ré-ordonnancements de paquets dans le canal capteur-contrôleur sont également considérés. De plus, cette méthode est validée par l’asservissement visuel d’un pendule inverse commandé en réseau. Les performances obtenues sont meilleures que les méthodes de commande non-prédictives classiques
Time-delay is a widely-found phenomenon (i.e. physical dead time, communication latency, computation time) in real control systems, which can degrade the performances of the system or destabilize the system. If the time-delay is small, then the closed-loop stability can be guaranteed with conventional control techniques; but these techniques are no longer effective if the time-delay is long. This thesis is dedicated to the control of time-delaysystemswithunknown or uncertain long time-delays. In order to compensate long time-delays, the predictor-based control technique is adopted, and the delay estimation techniques are developed to assist the predictor-based controller. According to the different types of the systems and the time-delays, three objectives are analyzed in the thesis. The first objective considers the control of LTI systems with unknown constant delays, a new type of delay estimator is proposed to estimate the unknown time-delays, then it is plugged into apredictor-based controller to stabilize the system. The second objective focuses on the practical stabilization of remote control systems with unknown time-varying delays, at this time, the time-delays are estimated by a practical way: a specific communication loop is used to estimate the round-trip delay in finite time, and the system is stabilized with a predictor-based controller. This practical delay estimation algorithm is implemented on a real WiFi network, it can estimate the time-varying delays with good performances and robustness. The last objective is devoted to the control of networked control systems with time-varying delays, the discrete predictor-based control techniques are used to compensate long time-varyingdelays,and the packet reordering in the sensor-to-controller channel is also considered. Moreover, this control solution is validated on a networked visual servo inverted pendulum system, and the control performances are fairly better than the non-predictive control methods

On considère la synthèse de la commande basée sur un asservissement affecté par des retards. L’approche utilisée repose sur des méthodes ensemblistes. Une partie de cette thèse est consacrée à une conception de commande active pour la compensation des retards qui apparaissent dans des canaux de communication entre le capteur et correcteur. Ce problème est considéré dans une perspective générale du cadre de commande tolérante aux défauts où des retards variés sont vus comme un mode particulier de dégradation du capteur. Le cas avec transmission de mesure retardée pour des systèmes avec des capteurs redondants est également examiné. Par conséquent, un cadre unifié est proposé afin de régler le problème de commande basé sur la transmission des mesures avec retard qui peuvent également être fournies par des capteurs qui sont affectés par des défauts soudains.Dans la deuxième partie le concept d’invariance positive pour des systèmes linéaires à retard à temps discret est exposé. En ce qui concerne l’invariance pour cette classe des systèmes dynamiques, il existe deux idées principales. La première approche repose sur la réécriture d’un tel système dans l’espace d’état augmenté et de le considérer comme un système linéaire. D’autre part, la seconde approche considère l’invariance dans l’espace d’état initial. Cependant, la caractérisation d’un tel ensemble invariant est encore une question ouverte, même pour le cas linéaire. Par conséquent, l’objectif de cette thèse est d’introduire une notion générale d’invariance positive pour des systèmes linéaires à retard à temps discret. Également, certains nouveaux éclairages sur l’existence et la construction pour les ensembles invariants positifs robustes sont détaillés. En outre, les nouveaux concepts d’invariance alternatives sont décrits
We considered the process regulation which is based on feedback affected by varying delays. Proposed approach relies on set-based control methods. One part of the thesis examines active control design for compensation of delays in sensor-to controller communication channel. This problem is regarded in a general perspective of the fault tolerant control where delays are considered as a particular degradation mode of the sensor. Obtained results are also adapted to the systems with redundant sensing elements that are prone to abrupt faults. In this sense, an unified framework is proposed in order to address the control design with outdated measurements provided by unreliable sensors.Positive invariance for linear discrete-time systems with delays is outlined in the second part of the thesis. Concerning this class of dynamics, there are two main approaches which define positive invariance. The first one relies on rewriting a delay-difference equation in the augmented state-space and applying standard analysis and control design tools for the linear systems. The second approach considers invariance in the initial state-space. However, the initial state-space characterization is still an open problem even for the linear case and it represents our main subject of interest. As a contribution, we provide new insights on the existence of the positively invariant sets in the initial state-space. Moreover, a construction algorithm for the minimal robust D-invariant set is outlined. Additionally, alternative invariance concepts are discussed

Hosts in the peer-to-peer networks need to communicate to each other directly, but majority of nodes in the Internet are private nodes, that is they are behind Network Address Translators(NAT), and cannot be reached directly like a public node. Therefore, NAT traversal techniques are required to enable nodes to make end-to-end connections. These techniques seems to be more effective over UDP transport compared to TCP. However, standard UDP lacks some useful features, such as reliability and in-order delivery of packets. It also does not have congestion control mechanism to prevent congestion in the links. In this protocol, named RABAT, we are going to present a transport library over UDP for peer-to-peer applications that provides a delay-based congestion control mechanism and also in-order delivery of packets. Our congestion control mechanism is derived from LEDBAT draft [8] and reliability implementation is based on standard TCP. RABAT provides both intra- and inter-protocol fairness, which in case of the latter is back-off to TCP. The protocol also enables users to change priority of the running transports at runtime. To the best of our knowledge, this is the first open-source implementation of LEDBAT in java.

Real-time control delay estimation is an important performance measure for any intersection to improve the signal timing plans dynamically in real-time and hence improve the overall system performance. Control delay estimates helps to determine the level-of-service (LOS) characteristics of various approaches at an intersection and takes into account deceleration delay, stopped delay and acceleration delay. All kinds of traffic delay calculation especially control delay calculation has always been complicated and laborious as there never existed a low-cost direct method to find them in real-time from the field. A recent validated technology called Bluetooth Median Access Control (MAC) ID matching traffic data collection technology seems to hold promise for continuous and cost-effective traffic data collection. Bluetooth traffic data synchronized with vehicle trajectory plot generated from GPS probe vehicle runs has been used to develop control delay models which has a potential to predict the control delays in real-time based on Bluetooth detection error parameters in field. Incorporating control delay estimates in real-time traffic control management would result in significant improvement in overall system performance.
Master of Science

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Neste trabalho, propomos uma abordagem de Controle Preditivo Baseado em Modelo Neural (Neural Based Model Predictive Control - N-MPC) para lidar com atrasos na planta de direção de carros autônomos. Examinamos a abordagem N-MPC como uma alternativa para a implementação do subsistema de controle de direção da Intelligent and Autonomous Robotic Automobile (IARA). Para isso, comparamos a solução padrão, baseada na abordagem de controle Proporcional Integral Derivativo (PID), com a abordagem N-MPC. O subsistema de controle de direção PID funciona bem na IARA para velocidades de até 25 km/h. No entanto, acima desta velocidade, atrasos na Planta de Direção da IARA são muito elevados para permitir uma operação adequada usando uma abordagem PID. Modelamos a Planta de Direção da IARA usando uma rede neural e empregamos esse modelo neural na abordagem N-MPC. A abordagem N-MPC superou a abordagem PID reduzindo o impacto de atrasos na Planta de Direção de IARA e permitindo a operação autônoma da IARA em velocidades de até 37 km/h um aumento de 48% na velocidade máxima estável

While research investigating the effectiveness of rehabilitation programs for adolescent substance use has increased in recent years, few studies have explored predictors of differential response to these rehabilitation programs. Delay of gratification (DG), which refers to the tendency to forego strong immediate satisfaction in the pursuit of larger long-term rewards, is one factor potentially relevant to all rehabilitation programs, as substance use can be characterized as a choice between short-lasting satisfaction from drug consumption and long-term benefits from abstinence. This study aims at investigating the changes of delay of gratification and the relationship between delay of gratification, future orientation and drug avoidance throughout a drug rehabilitation programme. A sample of one hundred and eleven students in Christian Zheng Sheng College was recruited to participate in this longitudinal study with four waves of data collection. The findings of the present study contribute to the literature of risky behavior by demonstrating the relationship between delay of gratification and drug avoidance, as well as the finding that delay of gratification is a changeable trait which can be strengthened through interventions. Further study will be required to examine the mechanism of change in delay of gratification and drug avoidance, as well as the influences of future orientation on delay of gratification and drug avoidance.
published_or_final_version
Clinical Psychology
Master
Master of Social Sciences

In this thesis study, it is aimed to improve the performance of an Internet-based teleoperation system enabling the remote operation of a 6 DOF industrial robot. In order to improve the safety and efficiency of the teleoperation, stability and synchronization (hand-eye coordination) are considered. The selected communication medium between the human operator and remote robot is the Internet. The variable time delays and nondeterministic characteristics of the Internet may lead to instability of the teleoperation system. Considering the disturbing effects of the Internet onto the transmission, an event-based control approach is used in order to improve the stability of the teleoperation system. Besides, a visual feedback system is developed and a force-feedback mouse is designed in order to improve synchronization between the human operator and robot during the command generation according to the feedback obtained from the control system. A client-server software application is developed to interface the human operator with remote environment. It is observed that, using the event-based control approach in the operation makes the teleoperation stable and improves the synchronization ability. Implementation of visual feedback and force-feedback mouse to the teleoperation system improves the human operator&rsquo
s ability to perform remote operation.

Networked control over wireless networks is of growing importance in many application domains such as industrial control, building automation and transportation systems. Wide deployment however, requires systematic design tools to enable efficient resource usage while guaranteeing close-loop control performance. The control system may be greatly affected by the inherent imperfections and limitations of the wireless medium and malfunction of system components. In this thesis, we make five important contributions that address these issues.  In the first contribution, we consider event- and self-triggered control and investigate how to efficiently tune and execute these paradigms for appropriate control performance. Communication strategies for aperiodic control are devised, where we jointly address the selection of medium-access control and scheduling policies. Experimental results show that the best trade-off is obtained by a hybrid scheme, combining event- and self-triggered control together with contention-based and contention-free medium access control. The second contribution proposes an event-based method to select between fast and slow periodic sampling rates. The approach is based on linear quadratic control and the event condition is a quadratic function of the system state. Numerical and experimental results show that this hybrid controller is able to reduce the average sampling rate in comparison to a traditional periodic controller, while achieving the same closed-loop control performance. In the third contribution, we develop compensation methods for out-of-order communications and time-varying delays using a game-theoretic minimax control framework. We devise a linear temporal coding strategy where the sensor combines the current and previous measurements into a single packet to be transmitted. An experimental evaluation is performed in a multi-hop networked control scenario with a routing layer vulnerability exploited by a malicious application. The experimental and numerical results show the advantages of the proposed compensation schemes. The fourth contribution proposes a distributed reconfiguration method for sensor and actuator networks. We consider systems where sensors and actuators cooperate to recover from faults. Reconfiguration is performed to achieve model-matching, while minimizing the steady-state estimation error covariance and a linear quadratic control cost. The reconfiguration scheme is implemented in a room heating testbed, and experimental results demonstrate the method's ability to automatically reconfigure the faulty system in a distributed and fast manner. The final contribution is a co-simulator, which combines the control system simulator Simulink with the wireless network simulator COOJA. The co-simulator integrates physical plant dynamics with realistic wireless network models and the actual embedded software running on the networked devices. Hence, it allows for the validation of the complete wireless networked control system, including the study of the interactions between software and hardware components.

QC 20140929

This dissertation addresses the development of integrative modeling strategies capable of combining deterministic and stochastic, discrete and continuous, as well as multi-scale features. The first set of studies combines the purely deterministic modeling methodology of Biochemical Systems Theory (BST) with a hybrid approach, using Functional Petri Nets, which permits the account of discrete features or events, stochasticity, and different types of delays. The efficiency and significance of this combination is demonstrated with several examples, including generic biochemical networks with feedback controls, gene regulatory modules, and dopamine based neuronal signal transduction. A study expanding the use of stochasticity toward systems with small numbers of molecules proposes a rather general strategy for converting a deterministic process model into a corresponding stochastic model. The strategy characterizes the mathematical connection between a stochastic framework and the deterministic analog. The deterministic framework is assumed to be a generalized mass action system and the stochastic analogue is in the format of the chemical master equation. The analysis identifies situations where internal noise affecting the system needs to be taken into account for a valid conversion from a deterministic to a stochastic model. The conversion procedure is illustrated with several representative examples, including elemental reactions, Michaelis-Menten enzyme kinetics, a genetic regulatory motif, and stochastic focusing. The last study establishes two novel, particle-based methods to simulate biochemical diffusion-reaction systems within crowded environments. These simulation methods effectively simulate and quantify crowding effects, including reduced reaction volumes, reduced diffusion rates, and reduced accessibility between potentially reacting particles. The proposed methods account for fractal-like kinetics, where the reaction rate depends on the local concentrations of the molecules undergoing the reaction. Rooted in an agent based modeling framework, this aspect of the methods offers the capacity to address sophisticated intracellular spatial effects, such as macromolecular crowding, active transport along cytoskeleton structures, and reactions on heterogeneous surfaces, as well as in porous media. Taken together, the work in this dissertation successfully developed theories and simulation methods which extend the deterministic, continuous framework of Biochemical Systems Theory to allow the account of delays, stochasticity, discrete features or events, and spatial effects for the modeling of biological systems, which are hybrid and multiscale by nature.

Cette thèse traite le problème de la conception des asservissements en vitesse de vérins hydrauliques. Le contrôleur utilisé implémente la commande coordonnée des mouvements des outils de pelleteuse. Les problèmes de synthèse des lois de commande sont étudiés à partir du modèle dynamique du bras d'une pelleteuse. Des représentations très simplifiées sont proposées afin de concevoir des algorithmes de commande. Les simplifications sont traduites par la présence d'un terme global inconnu dont les effets sont estimés en ligne. Une variante à temps continu de la méthode dite Time Delay Contrai (TDC) est proposée. Elle consiste à remplacer un opérateur de retard pur par une approximation de Padé. Une nouvelle approche de synthèse de lois de commande échantillonnées-bloquées est aussi proposée. La nouvelle loi est obtenue directement à partir d'un modèle dynamique simplifié à temps discrétisé. Les résultats obtenus par simulations et par expérimentations valident les approches proposées
The design and implementation of a velocity controller for hydraulic actuators is the subject of this thesis. The controller is used in order to achieve coordinated motion control of End effectors of excavators. A dynamic model of an excavator arm is studied in detail to give a full insight into the problem of modelling of such a system. An alternative simplified model is proposed in order to obtain a control law. The simplifications are represented by a global unknown term that is estimated online by the control algorithm. An alternative approach to Time Delay Control (TDC) method is proposed in the continuous time domain. Ln the proposed method, ail the delays disappear, and there is no need of measuring the derivatives of the state vector. A new discrete-time design method is also developed. The discrete-time law is obtained directly from a simplified discrete-time model. Extensive computer simulations and experimental results were obtained to validate the new control methods

In this thesis, we develop numerical methods for solving five nonstandard optimal control problems. The main idea of each method is to reformulate the optimal control problem as, or approximate it by, a nonlinear programming problem. The decision variables in this nonlinear programming problem influence its cost function (and constraints, if it has any) implicitly through the dynamic system. Hence, deriving the gradient of the cost and the constraint functions is a difficult task. A major focus of this thesis is on developing methods for computing these gradients. These methods can then be used in conjunction with a gradient-based optimization technique to solve the optimal control problem efficiently.The first optimal control problem that we consider has nonlinear inequality constraints that depend on the state at two or more discrete time points. These time points are decision variables that, together with a control function, should be chosen in an optimal manner. To tackle this problem, we first approximate the control by a piecewise constant function whose values and switching times (the times at which it changes value) are decision variables. We then apply a novel time-scaling transformation that maps the switching times to fixed points in a new time horizon. This yields an approximate dynamic optimization problem with a finite number of decision variables. We develop a new algorithm, which involves integrating an auxiliary dynamic system forward in time, for computing the gradient of the cost and constraints in this approximate problem.The second optimal control problem that we consider has nonlinear continuous inequality constraints. These constraints restrict both the state and the control at every point in the time horizon. As with the first problem, we approximate the control by a piecewise constant function and then transform the time variable. This yields an approximate semi-infinite programming problem, which can be solved using a penalty function algorithm. A solution of this problem immediately furnishes a suboptimal control for the original optimal control problem. By repeatedly increasing the number of parameters used in the approximation, we can generate a sequence of suboptimal controls. Our main result shows that the cost of these suboptimal controls converges to the minimum cost.The third optimal control problem that we consider is an applied problem from electrical engineering. Its aim is to determine an optimal operating scheme for a switchedcapacitor DC-DC power converter—an electronic device that transforms one DC voltage into another by periodically switching between several circuit topologies. Specifically, the optimal control problem is to choose the times at which the topology switches occur so that the output voltage ripple is minimized and the load regulation is maximized. This problem is governed by a switched system with linear subsystems (each subsystem models one of the power converter’s topologies). Moreover, its cost function is non-smooth. By introducing an auxiliary dynamic system and transforming the time variable (so that the topology switching times become fixed), we derive an equivalent semi-infinite programming problem. This semi-infinite programming problem, like the one that approximates the continuously-constrained optimal control problem, can be solved using a penalty function algorithm.The fourth optimal control problem that we consider involves a general switched system, which includes the model of a switched-capacitor DC-DC power converter as a special case. This switched system evolves by switching between several subsystems of nonlinear ordinary differential equations. Furthermore, each subsystem switch is accompanied by an instantaneous change in the state. These instantaneous changes—so-called state jumps—are influenced by control variables that, together with the subsystem switching times, should be selected in an optimal manner. As with the previous optimal control problems, we tackle this problem by transforming the time variable to obtain an equivalent problem in which the switching times are fixed. However, the functions governing the state jumps in this new problem are discontinuous. To overcome this difficulty, we introduce an approximate problem whose state jumps are governed by smooth functions. This approximate problem can be solved using a nonlinear programming algorithm. We prove an important convergence result that links the approximate problem’s solution with the original problem’s solution.The final optimal control problem that we consider is a parameter identification problem. The aim of this problem is to use given experimental data to identify unknown state-delays in a nonlinear delay-differential system. More precisely, the optimal control problem involves choosing the state-delays to minimize a cost function measuring the discrepancy between predicted and observed system output. We show that the gradient of this cost function can be computed by solving an auxiliary delay-differential system. On the basis of this result, the optimal control problem can be formulated—and hence solved—as a standard nonlinear programming problem.

In conventional bilateral teleoperation, transmission delay over the Internet can potentially cause instability. The wave variable algorithm guarantees stability under varying transmission delay at the cost of poor transient performance. Adding a predictor on the master side can reduce this undesirable side-effect, but that would require a slave model. An inaccurate slave model used in the predictor as well as variations in transmission delay, both of which are likely under realistic situations, can result in steady state errors. A direct drift control algorithm is used to drive this error to zero regardless of the source of error. A semi-adaptive predictor that can distinguish between free space and rigid contact environment is used to provide more accurate force feedback on the master side. A full adaptive predictor is also used that estimates the slave environment parameters using recursive least squares with a forgetting factor. This research presents the experimental results and evaluations of the wave variable based methods under a realistic operation environment using a real master and slave. The effectiveness of this algorithm is fully evaluated using human subjects with no previous experience in haptics. Three algorithms are tested using PHANTOM brand haptic devices as master and slave: conventional bilateral teleoperation with no transmission delay as control, wave variable teleoperation with approximately 200 ms transmission delay one way, and wave variables with adaptive predictor and direct drift control with approximately 200 ms transmission delay one way. For each algorithm the human subjects are asked to perform three simple tasks: use the master to force the slave to track a reference trajectory in free space with the least amount of error, identify a contour surface on the slave side as accurately as possible using only haptic information from the master, and navigate a simple maze on the slave side in the least amount of time using haptic information from the master.

Transition delay in boundary-layer flows is achieved via reactive control of flow instabilities, i.e. Tollmien-Schlichting (TS) waves. Adaptive and model-based control techniques are investigated by means of direct numerical simulations (DNS) and experiments. The action of actuators localised in the wall region is prescribed based on localised measurement of the disturbance field; in particular, plasma actuators and surface hot-wire sensors are considered. Performances and limitations of this control approach are evaluated both for two-dimensional (2D) and three-dimensional (3D) disturbance scenarios. The focus is on the robustness properties of the investigated control techniques; it is highlighted that static model-based control, such as the linear-quadratic- Gaussian (LQG) regulator, is very sensitive to model-inaccuracies. The reason for this behaviour is found in the feed-forward nature of the adopted sensor/actuator scheme; hence, a second, downstream sensor is introduced and actively used to recover robustness via an adaptive filtered-x least-mean-squares (fxLMS) algorithm. Furthermore, the model of the flow required by the control algorithm is reduced to a time delay. This technique, called delayed-x least-mean-squares (dxLMS) algorithm, allows taking a step towards a self-tuning controller; by introducing a third sensor it is possible to compute on-line the suitable time-delay model with no previous knowledge of the controlled system. This self-tuning approach is successfully tested by in-flight experiments on a motor-glider. Lastly, the transition delay capabilities of the investigated control con- figuration are confirmed in a complex disturbance environment. The flow is perturbed with random localised disturbances inside the boundary layer and the laminar-to-turbulence transition is delayed via a multi-input-multi-output (MIMO) version of the fxLMS algorithm. A positive theoretical net-energy- saving is observed for disturbance amplitudes up to 2% of the free-stream velocity at the actuation location, reaching values around 1000 times the input power for the lower disturbance amplitudes that have been investigated.
I den här avhandlingen har reglertekniska metoder tillämpats för att försena omslaget från ett laminärt till ett turbulent gränsskikt genom att dämpa tillväxten av små instabiliteter, så kallade Tollmien-Schlichting vågor. Adaptiva och modellbaserade metoder för reglering av strömning har undersökts med hjälp av numeriska beräkningar av Navier-Stokes ekvationer, vindtunnelexperiment och även genom direkt tillämpning på flygplan. Plasmaaktuatorer och varmtrådsgivare vidhäftade på ytan av plattan eller vingen har använts i experimenten och modellerats i beräkningarna. Prestanda och begränsningar av den valda kontrollstrategin har utvärderats för både tvådimensionella och tredimensionella gränsskiktsinstabiliteter. Fokus har varit på metodernas robusthet, där vi visar att statiska metoder som linjär-kvadratiska regulatorer (LQG) är mycket känsliga för avvikelser från den nominella modellen. Detta beror främst på att regulatorer agerar i förkompenseringsläge (”feed-foward”) på grund av strömningens karaktär och placeringen av givare och aktuatorer. För att minska känsligheten mot avvikelser och därmed öka robustheten har en givare införts nedströms och en adaptiv fXLMS algoritm (filtered-x least-mean-squares) har tillämpats.                  Vidare har modelleringen av fXLMS-algoritmen förenklats genom att ersätta överföringsfunktionen mellan aktuatorer och givare med en lämplig tidsfördröjning.  Denna  metod som kallas för dxLMS (delayed-x least-mean-squares) kräver att ytterligare en givare införs långt uppströms för att kunna uppskatta hastigheten på de propagerande instabilitetsvågorna. Denna teknik har tillämpats framgångsrikt för reglering av gränsskiktet på vingen av ett segelflygplan. Slutligen har de reglertekniska metoderna testas för komplexa slumpmässiga tredimensionella störningar som genererats uppströms lokalt i gränsskiktet. Vi visar att en signifikant försening av laminärt-turbulentomslag äger rum med hjälp av en fXLMS algoritm. En analys av energibudgeten visar att för ideala aktuatorer och givare kan den sparade energiåtgången på grund av minskad väggfriktion vara upp till 1000 gånger större än den energi som använts för reglering.

Traditional generators have been decommissioned or replaced by renewable energy generation due to utility long-standing goals. However, instead of flattening the entire plant, the rotating mass of generator can be utilized as a storage unit (inertia resource) to mitigate the frequency swings during transient caused by the renewables. The goal of this work is to design a control strategy utilizing the decommissioned generator interfaced with power grid via a back-to-back converter to provide inertia support. This is referred to as decoupled synchronous machine system (DSMS). On top of that, the grid-side converter is capable of providing reactive power as an auxiliary voltage controller. However, in a practical setting, for power utilities, the detailed state equations of such device as well as the complicated nonlinear power system are usually unobtainable making the controller design a challenging problem. Therefore, a model free, purely data-driven strategy for the nonlinear controller design using Koopman operator-based framework is proposed. Besides, the time delay embedding technique is adopted together with Koopman operator theory for the nonlinear system identification. Koopman operator provides a linear representation of the system and thereby the classical linear control algorithms can be applied. In this work, model predictive control is adopted to cope with the constraints of the control signals. The effectiveness and robustness of the proposed system are demonstrated in Kundur two-area system and IEEE 39-bus system.
Doctor of Philosophy

In boundary-layer flows it is possible to reduce the friction drag by breaking the path from laminar to turbulent state. In low turbulence environments, the laminar-to-turbulent transition is dominated by local flow instabilities – Tollmien-Schlichting (TS) waves – that exponentially grows while being con- vected by the flow and, eventually, lead to transition. Hence, by attenuating these disturbances via localised forcing in the flow it is possible to delay farther downstream the onset of turbulence and reduce the friction drag. Reactive control techniques are widely investigated to this end. The aim of this work is to compare model-based and adaptive control techniques and show how the adaptivity is crucial to control TS-waves in real applications. The control design consists in (i) choosing sensors and actuators and (ii) designing the system responsible to process on-line the measurement signals in order to compute an appropriate forcing by the actuators. This system, called compen- sator, can be static or adaptive, depending on the possibility of self-adjusting its response to unmodelled flow dynamics. A Linear Quadratic Gaussian (LQG) regulator is chosen as representative of static controllers. Direct numerical simulations of the flow are performed to provide a model for the compensator design and test its performance. An adaptive Filtered-X Least-Mean-Squares (FXLMS) compensator is also designed for the same flow case and its per- formance is compared to the model-based compensator via simulations and experiments. Although the LQG regulator behaves better at design conditions, it lacks robustness to small flow variations. On the other hand, the FXLMS compensator proved to be able to adapt its response to overcome the varied conditions and perform an adequate control action. It is thus found that an adaptive control technique is more suitable to delay the laminar-to-turbulent transition in situations where an accurate model of the flow is not available.
I det tunna gränsskikt som uppstår en yta, kan friktionen minskas genom att förhindra omslag från ett laminärt till ett turbulent flöde. När turbulensnivån är låg  i omgivningen, domineras till en början omslaget av lokala instabiliteter (Tollmien-Schlichting (TS) v ågor) som växer i en exponentiell takt samtidigt som de propagerar nedströms. Därför, kan man förskjuta omslaget genom att dämpa TS vågors tillväxt i ett gränsskikt och därmed minska friktionen.Med detta mål i sikte, tillämpas och jämförs två reglertekniska metoder, nämligen en adaptiv signalbaserad metod och en statiskt modellbaserad metod. Vi visar att adaptivitet är av avgörande betydelse för att kunna dämpa TS vågor i en verklig miljö. Den reglertekniska konstruktionen består av val av givare och aktuatorer samt att bestämma det system som behandlar mätsignaler (on- line) för beräkning av en lämplig signal till aktuatorer. Detta system, som kallas för en kompensator, kan vara antingen statisk eller adaptiv, beroende på om det har möjlighet till att anpassa sig till omgivningen. En så kallad linjär regulator (LQG), som representerar den statiska kompensator, har tagits fram med hjälp av numeriska simuleringar of strömningsfältet. Denna kompensator jämförs med en adaptiv regulator som kallas för Filtered-X Least-Mean-Squares (FXLMS) både experimentellt och numeriskt. Det visar sig att LQG regulatorn har en bättre prestanda än FXLMS för de parametrar som den var framtagen för, men brister i robusthet. FXLMS å andra sidan, anpassar sig till icke- modellerade störningar och variationer, och kan därmed hålla en god och jämn prestanda.Man kan därmed dra slutsaten att adaptiva regulatorer är mer lämpliga för att förhala omslaget fr ån laminär till turbulent strömning i situationer då en exakt modell av fysiken saknas.

QC 20141020

This work is to investigate the performance of two Kalman Filter Algorithms, namely Linear Kalman Filter and Extended Kalman Filter on control-based human motion prediction in a real-time teleoperation. The Kalman Filter Algorithm has been widely used in research areas of motion tracking and GPS-navigation. However, the potential of human motion prediction by utilizing this algorithm is rarely being mentioned. Combine with the known issue - the delay issue in today’s teleoperation services, the author decided to build a prototype of simple teleoperation model based on the Kalman Filter Algorithm with the aim of eliminated the unsynchronization between the user’s inputs and the visual frames, where all the data were transferred over the network. In the first part of the thesis, two types of Kalman Filter Algorithm are applied on the prototype to predict the movement of the robotic arm based on the user’s motion applied on a Haptic Device. The comparisons in performance among the Kalman Filters have also been focused. In the second part, the thesis focuses on optimizing the motion prediction which based on the results of Kalman filtering by using the smoothing algorithm. The last part of the thesis examines the limitation of the prototype, such as how much the delays are accepted and how fast the movement speed of the Phantom Haptic can be, to still be able to obtain reasonable predations with acceptable error rate.   The results show that the Extended Kalman Filter has achieved more advantages in motion prediction than the Linear Kalman Filter during the experiments. The unsynchronization issue has been effectively improved by applying the Kalman Filter Algorithm on both state and measurement models when the latency is set to below 200 milliseconds. The additional smoothing algorithm further increases the accuracy. More important, it also solves shaking issue on the visual frames on robotic arm which is caused by the wavy property of the Kalman Filter Algorithm. Furthermore, the optimization method effectively synchronizes the timing when robotic arm touches the interactable object in the prediction.   The method which is utilized in this research can be a good reference for the future researches in control-based human motion tracking and prediction.
Detta arbete fokuserar på att undersöka prestandan hos två Kalman Filter Algoritmer, nämligen Linear Kalman Filter och Extended Kalman Filter som används i realtids uppskattningar av kontrollbaserad mänsklig rörelse i teleoperationen. Dessa Kalman Filter Algoritmer har används i stor utsträckning forskningsområden i rörelsespårning och GPS-navigering. Emellertid är potentialen i uppskattning av mänsklig rörelse genom att utnyttja denna algoritm sällan nämnas. Genom att kombinera med det kända problemet – fördröjningsproblem i dagens teleoperation tjänster beslutar författaren att bygga en prototyp av en enkel teleoperation modell vilket är baserad på Kalman Filter algoritmen i syftet att eliminera icke-synkronisering mellan användarens inmatningssignaler och visuella information, där alla data överfördes via nätverket. I den första delen av avhandlingen appliceras både Kalman Filter Algoritmer på prototypen för att uppskatta rörelsen av robotarmen baserat på användarens rörelse som anbringas på en haptik enhet. Jämförelserna i prestandan bland de Kalman Filter Algoritmerna har också fokuserats. I den andra delen fokuserar avhandlingen på att optimera uppskattningar av rörelsen som baserat på resultaten av Kalman-filtrering med hjälp av en utjämningsalgoritm. Den sista delen av avhandlingen undersökes begräsning av prototypen, som till exempel hur mycket fördröjningar accepteras och hur snabbt den haptik enheten kan vara, för att kunna erhålla skäliga uppskattningar med acceptabel felfrekvens.   Resultaten visar att den Extended Kalman Filter har bättre prestandan i rörelse uppskattningarna än den Linear Kalman Filter under experimenten. Det icke-synkroniseringsproblemet har förbättrats genom att tillämpa de Kalman Filter Algoritmerna på både statliga och värderingsmodeller när latensen är inställd på under 200 millisekunder. Den extra utjämningsalgoritmen ökar ytterligare noggrannheten. Denna algoritm löser också det skakande problem hos de visuella bilder på robotarmen som orsakas av den vågiga egenskapen hos Kalman Filter Algoritmen. Dessutom effektivt synkroniserar den optimeringsmetoden tidpunkten när robotarmen berör objekten i uppskattningarna.   Den metod som används i denna forskning kan vara en god referens för framtida undersökningar i kontrollbaserad rörelse- spåning och uppskattning.

The research is motivated by real applications, such as pasteurization plant, water networks and autonomous system, which each of them require a specific control system to provide proper management able to take into account their particular features and operating limits in presence of uncertainties related to their operation and failures from component breakdowns. According to that most of the real systems have nonlinear behaviors, it can be approximated them by polytopic linear uncertain models such as Linear Parameter Varying (LPV) and Takagi-Sugeno (TS) models. Therefore, a new economic Model Predictive Control (MPC) approach based on LPV/TS models is proposed and the stability of the proposed approach is certified by using a region constraint on the terminal state. Besides, the MPC-LPV strategy is extended based on the system with varying delays affecting states and inputs. The control approach allows the controller to accommodate the scheduling parameters and delay change. By computing the prediction of the state variables and delay along a prediction time horizon, the system model can be modified according to the evaluation of the estimated state and delay at each time instant. To increase the system reliability, anticipate the appearance of faults and reduce the operational costs, actuator health monitoring should be considered. Regarding several types of system failures, different strategies are studied for obtaining system failures. First, the damage is assessed with the rainflow-counting algorithm that allows estimating the component’s fatigue and control objective is modified by adding an extra criterion that takes into account the accumulated damage. Besides, two different health-aware economic predictive control strategies that aim to minimize the damage of components are presented. Then, economic health-aware MPC controller is developed to compute the components and system reliability in the MPC model using an LPV modeling approach and maximizes the availability of the system by estimating system reliability. Additionally, another improvement considers chance-constraint programming to compute an optimal list replenishment policy based on a desired risk acceptability level, managing to dynamically designate safety stocks in flowbased networks to satisfy non-stationary flow demands. Finally, an innovative health-aware control approach for autonomous racing vehicles to simultaneously control it to the driving limits and to follow the desired path based on maximization of the battery RUL. The proposed approach is formulated as an optimal on-line robust LMI based MPC driven from Lyapunov stability and controller gain synthesis solved by LPV-LQR problem in LMI formulation with integral action for tracking the trajectory.
Esta tesis pretende proporcionar contribuciones teóricas y prácticas sobre seguridad y control de sistemas industriales, especialmente en la forma maten ática de sistemas inciertos. La investigación está motivada por aplicaciones reales, como la planta de pasteurización, las redes de agua y el sistema autónomo, cada uno de los cuales requiere un sistema de control específico para proporcionar una gestión adecuada capaz de tener en cuenta sus características particulares y limites o de operación en presencia de incertidumbres relacionadas con su operación y fallas de averías de componentes. De acuerdo con que la mayoría de los sistemas reales tienen comportamientos no lineales, puede aproximarse a ellos mediante modelos inciertos lineales politopicos como los modelos de Lineal Variación de Parámetros (LPV) y Takagi-Sugeno (TS). Por lo tanto, se propone un nuevo enfoque de Control Predictivo del Modelo (MPC) económico basado en modelos LPV/TS y la estabilidad del enfoque propuesto se certifica mediante el uso de una restricción de región en el estado terminal. Además, la estrategia MPC-LPV se extiende en función del sistema con diferentes demoras que afectan los estados y las entradas. El enfoque de control permite al controlador acomodar los parámetros de programación y retrasar el cambio. Al calcular la predicción de las variables de estado y el retraso a lo largo de un horizonte de tiempo de predicción, el modelo del sistema se puede modificar de acuerdo con la evaluación del estado estimado y el retraso en cada instante de tiempo. Para aumentar la confiabilidad del sistema, anticipar la aparición de fallas y reducir los costos operativos, se debe considerar el monitoreo del estado del actuador. Con respecto a varios tipos de fallas del sistema, se estudian diferentes estrategias para obtener fallas del sistema. Primero, el daño se evalúa con el algoritmo de conteo de flujo de lluvia que permite estimar la fatiga del componente y el objetivo de control se modifica agregando un criterio adicional que tiene en cuenta el daño acumulado. Además, se presentan dos estrategias diferentes de control predictivo económico que tienen en cuenta la salud y tienen como objetivo minimizar el daño de los componentes. Luego, se desarrolla un controlador MPC económico con conciencia de salud para calcular los componentes y la confiabilidad del sistema en el modelo MPC utilizando un enfoque de modelado LPV y maximiza la disponibilidad del sistema mediante la estimación de la confiabilidad del sistema. Además, otra mejora considera la programación de restricción de posibilidades para calcular una política ´optima de reposición de listas basada en un nivel de aceptabilidad de riesgo deseado, logrando designar dinámicamente existencias de seguridad en redes basadas en flujo para satisfacer demandas de flujo no estacionarias. Finalmente, un enfoque innovador de control consciente de la salud para vehículos de carreras autónomos para controlarlo simultáneamente hasta los límites de conducción y seguir el camino deseado basado en la maximización de la bacteria RUL. El diseño del control se divide en dos capas con diferentes escalas de tiempo, planificador de ruta y controlador. El enfoque propuesto está formulado como un MPC robusto en línea optimo basado en LMI impulsado por la estabilidad de Lyapunov y la síntesis de ganancia del controlador resuelta por el problema LPV-LQR en la formulación de LMI con acción integral para el seguimiento de la trayectoria.

Diplomová práce pojednává o stabilizaci diskrétního logistického modelu pomocí několika řídících metod. Je zde provedena především stabilizace rovnováh, 2-periodických cyklů a 3-periodických cyklů. Ke stabilizaci systému je využito proporčního zpětně-vazebního řízení, zpětně-vazebního řízení s časovým zpožděním a řízení založeného na predikci. U každé metody je diskutovaná stabilizační množina pro řídící zesilovač spolu s oblastmi stability pro odpovídající kontrolovaná řešení. Všechny teoretické výsledky jsou ilustrovány grafickými interpretacemi v softwaru MATLAB. Podpůrné výpočty jsou provedeny pomocí softwaru Maple.

L’optimisation des systèmes de groupes motopropulseurs (GMP) dans les automobiles modernes repose sur l’ingénierie des systèmes basée sur des modèles pour faire face à la complexité des systèmes automobiles et aux exigences de conception des commandes. Deux prérequis à l’optimisation du GMP sont le simulateur de GMP et la conception des commandes, assurant un fonctionnement satisfaisant du GMP pendant les cycles de conduite. Cette thèse s’articule autour de ces prérequis et fait partie de la phase model-in-the-loop du cycle de développement du contrôle. Elle vise d’abord à identifier des modèles linéaires boîtes noires de systèmes de GMP, car ils présentent des avantages d’accessibilité à la conception de la commande linéaire et de facilité d’intégration des modifications dans la définition technique du GMP. Elle vise également à identifier et à contrôler les systèmes de GMP à retard de transport car l’intégration du retard est cruciale pour la précision du modèle et l’optimalité de son contrôle. Sur ces bases, nous abordons le GMP du point de vue de la chaîne d’air d’un moteur essence. Nous identifions d’abord un modèle linéaire boîte noire state-space (SS), via un algorithme d’identification basé sur les méthodes subspace. Différents ordres de modèles et paramètres d’algorithmes sont testés et ceux donnant les meilleurs résultats d’identification et de validation sont indiqués, conduisant à un gain de temps de 85% pour des identifications futures similaires. Bien que cette partie considère l’ensemble de la chaîne d’air, le reste s’adresse aux certains de ses composants, notamment le papillon électrique, l’échangeur de chaleur et la recirculation des gaz d’échappement (EGR). Concernant le papillon électrique, nous nous inspirons des lois physiques régissant son fonctionnement pour construire un modèle mathématique linéaire à paramètres variables (LPV) SS, qui définit la structure vectorielle de régression du modèle LPV boîte noire ARX qui représente un banc d’essais du papillon et reflète ses nonlinéarités et discontinuités en variant entres ses zones fonctionnelles. Pour traiter les délais de transport de chaleur et de masse dans la chaîne d’air, nous nous référons respectivement à l’échangeur de chaleur et à l’EGR. La refonte des équations aux dérivées partielles (EDP) hyperboliques à dimensions infinies décrivant ces phénomènes de transport sous la forme d’un système à retard facilite l’identification du système et la conception du contrôle. Pour ce faire, le moyennage spatiale et la méthode des caractéristiques sont utilisés pour découpler les EDP hyperboliques décrivant les flux advectifs dans un échangeur de chaleur et pour les reformuler en un système à retard temporel. La méthode à descente de gradient cherche à réduire l’erreur entre la température de sortie du modèle et celle d’un banc d’essai d’échangeur de chaleur, pour identifier les paramètres du système à retard, qui dépasse les EDP en termes de précision d’identification et de temps de calcul. D’autre part, les EDP décrivant le transport de masse dans une EGR sont refondus en un système SS soumis à un retard de sortie. Pour réguler le rapport de gaz brûlé dans le gaz d’admission, la quantité de gaz recirculé est contrôlée à l’aide de deux approches de contrôle optimale indirecte, qui prennent en compte la nature infinie du modèle et qui sont accompagnées des méthodes du Lagrangien Augmenté et d’Uzawa pour respecter des contraintes d’entrée et d’état, permettant ainsi d’obtenir un contrôleur plus performant que le PID initialement existant. En générale, cette thèse se situe à mi-chemin entre les secteurs académique et industriel. En évaluant l’éligibilité de l’intégration des théories existants d’identification et de contrôle des systèmes dans des applications automobiles réelles, elle indique les avantages et les inconvénients de ces théories et ouvre de nouvelles perspectives dans l’optimisation des systèmes du GMP basée sur les modèles
Powertrain systems optimization in modern automobiles relies on model-based systems engineering to cope with the complex automotive systems and challenging control design requirements. Two prerequisites for model-based powertrain optimization are the powertrain simulator and the control design, which ensures a desirable powertrain operation during driving cycles. This thesis revolves around these prerequisites and belongs to the model-in-the-loop phase of the control development lifecycle. It first aims at identifying control-oriented powertrain systems models, particularly linear black-box models because of the merits they present in terms of accessibility to linear control design and facility of integrating changes in the powertrain system technical definition. It also aims at identifying and controlling powertrain systems featuring transport time delay because integrating the delay in the model and control design is crucial on the former’s system representability and on the latter’s optimality. Based on these premises, we address the powertrain from the engine air-path perspective. We first identify a linear black-box state-space (SS) model of a gasoline engine air-path, using an identification algorithm based on subspace methods. Different model orders and algorithm parameters are tested and those yielding the best identification and validation results are made clear, which leads to an 85% time gain in future similar identifications. While this part considers the air-path as a whole, the rest of the work focuses on specific air-path components, notably the electric throttle (ET), the heat-exchanger, and the exhaust gas recirculation (EGR). Regarding the ET, we inspire from the physical laws governing the throttle functioning to construct a linear-parameter-varying (LPV) mathematical SS model, which serves to set the regression vector structure of the LPV black-box ARX model, which is representative of an ET test bench and reflects its nonlinearities and discontinuities as it varies from one functioning zone to another. To address the questions of heat and mass transport time delays in the engine air-path, we refer to the heat exchanger and the EGR respectively. Recasting the infinite-dimensional hyperbolic partial differential equations (PDEs) describing these transport phenomena as a time-delay system facilitates the adjoint system identification and control design. To that end, a space-averaging technique and the method of characteristics are used to decouple the hyperbolic PDEs describing the advective flows in a heat exchanger, and to reformulate them as a time-delay system. Reducing the error between the output temperature of the model and that of a heat exchanger test-bench is what seeks the gradient-descent method used to identify the parameters of the time-delay system, which surpasses the PDEs in terms of identification accuracy and computational efficiency. On the other hand, the EGR is addressed from a control-oriented perspective, and the PDEs describing the mass transport phenomenon in its tubular structure are recast as a SS system subject to output delay. To regulate the burned gas ratio in the intake gas, the amount of recirculated gas is controlled using two indirect optimal control approaches, taking into account the model’s infinite-dimensional nature and accompanied with the Augmented Lagrangian Uzawa method to guarantee the respect of the input and state constraints, thus resulting in a controller of superior performance than the initially existing PID. In general, this thesis is located half-way between the academic and the industrial sectors. By evaluating the eligibility of integrating existing system identification and control theories in real automotive applications, it highlights the merits and demerits of these theories and opens up new prospects in the domain of model-based powertrain systems optimization

This thesis regards the problem of optimal management of water resources in inland navigation networks from a control theory perspective. In particular, the main objective to be attained consists in guaranteeing the navigability condition of the network, i.e., ensuring that the water levels are such that vessels can travel safely. More specifically, the water levels must be kept within an interval around the setpoint. Other common objectives include minimizing the operational cost and ensuring a long lifespan of the equipment. However, inland navigation networks are large-scale systems characterized by a number of features that complicate their management, namely complex dynamics, large time delays and negligible bottom slopes. In order to achieve the optimal management, the efficient control of the hydraulic structures, e.g., gates, weirs and locks, must be ensured. To this end, a control-oriented modeling approach is derived based on an existing simplified model obtained from the Saint-Venant equations. This representation reduces the complexity of the original model, provides flexibility and allows to coordinate current and delayed information in a systematic manner. However, the resulting model formulation belongs to the class of delayed descriptor systems, for which standard control and state estimation tools would need to be extended. Instead, model predictive control and moving horizon estimation can be easily adapted for this formulation, as well as being able to deal with physical and operational constraints in a natural manner. Due to the large dimensionality of inland navigation networks, a centralized implementation is often neither possible nor desirable. In this regard, non-centralized approaches are considered, decomposing the overall system in subsystems and distributing the computational burden among the local agents, each of them in charge of meeting the local objectives. Given the fact that inland navigation networks are strongly coupled systems, a distributed approach is followed, featuring a communication protocol among local agents. Despite the optimality of the computed solutions, state estimation will only be effective provided that the sensors acquire reliable data. Likewise, the control actions will only be applied correctly if the actuators are not impacted by faults. Indeed, any error can lead to an inefficient management of the system. Therefore, the last part of the thesis is concerned with the design of supervisory strategies that allow to detect and isolate faults in inland navigation networks. All the presented modeling, centralized and distributed control and state estimation and fault diagnosis approaches are applied to a realistic case study based on the inland navigation network in the north of France to validate their effectiveness.
Cette thèse contribue à répondre au problème de la gestion optimale des ressources en eau dans les réseaux de navigation intérieure du point de vue de la théorie du contrôle. Les objectifs principales à atteindre consistent à garantir la navigabilité des réseaux de voies navigables, veiller à la réduction des coûts opérationnels et à la longue durée de vie des équipements. Lors de la conception de lois de contrôle, les caractéristiques des réseaux doivent être prises en compte, à savoir leurs dynamiques complexes, des retards variables et l’absence de pente. Afin de réaliser la gestion optimale, le contrôle efficace des structures hydrauliques doit être assuré. A cette fin, une approche de modélisation orientée contrôle est dérivée. Cependant, la formulation obtenue appartient à la classe des systèmes de descripteurs retardés, pour lesquels la commande prédictive MPC et l’estimation d’état sur horizon glissant MHE peuvent être facilement adaptés à cette formulation, tout en permettant de gérer les contraintes physiques et opérationnelles de manière naturelle. En raison de leur grande dimensionnalité, une mise en œuvre centralisée n’est souvent ni possible ni souhaitable. Compte tenu du fait que les réseaux de navigation intérieure sont des systèmes fortement couplés, une approche distribuée est proposée, incluant un protocole de communication entre agents. Malgré l’optimalité des solutions, toute erreur peut entraîner une gestion inefficace du système. Par conséquent, les dernières contributions de la thèse concernent la conception de stratégies de supervision permettant de détecter et d’isoler les pannes des équipements. Toutes les approches présentées sont appliquées à une étude de cas réaliste basée sur le réseau de voies navigables du nord e la France afin de valider leur efficacité.
La present tesi versa sobre el problema de la gestió òptima dels recursos hídrics en vies de navegació interior des de la perspectiva de la teoria de control. Concretament, l’objectiu principal radica en garantir la condició de navegabilitat del s is tema. Dit d’una altra manera, es vol garantir que els nivells d’aigua siguin tals que les embarcacions puguin navegar-hi de forma segura. Aquest objectiu s’assoleix mantenint els nivells a l’interior d’un interval construït al voltant del punt d’operació. Altres objectius comuns en aquest context as piren a minimitzar els cos tos associats a l’operació dels equips, així com a prolongar-ne la seva vida útil. Ara bé, les vies de navegació interior són sistemes a gran escala caracteritzats per dinàmiques complexes, grans retards temporals i pendents negligibles, aspectes que en dificulten la gestió. Per tal d’assolir la ges tió òptima, s’ha de garantir un control eficient de les estructures hidràuliques tals com comportes, dics i rescloses. Amb aquesta finalitat, es deriva un modelat del sistema orientat a control basat en un model existent simplificat, obtingut a partir de les equacions de Saint-Venant. Aquesta nova representació redueix la complexitat del model original, proporciona flexibilitat i permet coordinar informació actual i retardada de manera sistemàtica. Malgrat això, la formulació resultant pertany a la classe de sistemes descriptors amb retard, per als quals les tècniques de control i d’estimació estàndards necessiten ser esteses. En canvi, el control predictiu basat en models i l’estimació d’estat amb horitzó lliscant es poden adaptar fàcilment a la formulació proposada. A més, són capaços de tractar amb restriccions físiques i operacionals de forma natural. Degut a les grans dimensions de les vies de navegació interior, una implementació centralitzada no resulta, tot sovint, ni possible ni desitjada. Per tal de pal·liar aquest problema, es consideren mètodes no centralitzats. D’aquesta manera, es descompon el sistema global en subsistemes i es distribueix la càrrega computacional del problema centralitzat entre els agents locals, de manera que cadascun d’ells s’encarrega de fer complir els objectius locals . En tant que les vies de navegació interior són sistemes fortament connectats, se segueix un plantejament distribuït, incloent un protocol de comunicació entre els agents locals. Malgrat la optimalitat dels resultats que les estratègies proposades puguin proporcionar, l’estimació d’estat només serà efectiva a condició que els sensors proveeixin informació fiable. Igualment, les accions de control únicament es podran aplicar correctament si els actuadors no estan afectats per fallades. En efecte, qualsevol error pot conduir a una gestió ineficaç del sistema. És per aquest motiu que la darrera part de la tes i tracta s obre el disseny d’estratègies de supervisió, que permetin detectar i aïllar fallades en vies de navegació interior. Tots els resultats de modelat, control i estimació d’es tat centralitzats i distribuïts, així com de diagnòstic de fallades, s’apliquen a un cas d’estudi realista, basat en les vies de navegació interior del nord de França, per tal de provar-ne la seva eficàcia.
La presente tesis versa sobre el problema de la gestión óptima de los recursos hídricos en vías de navegación interior desde la perspectiva de la teoría de control. En concreto, el objetivo principal consiste en garantizar la condición de navegabilidad del sistema, es decir, garantizar que los niveles de agua de los canales sean tales que las embarcaciones puedan navegar de forma segura. Dicho objetivo se consigue manteniendo los niveles dentro de un intervalo alrededor del punto de operación. Otros objetivos comunes consisten en minimizar los costes asociados a la operación de los equipos, así como a extender su vida útil. Hay que tener en cuenta que las vías de navegación interiores son sistemas a gran escala caracterizados por dinámicas complejas, grandes retardos temporales y pendientes prácticamente nulas, lo que dificulta su gestión. Para alcanzar la gestión óptima, se debe garantizar un control eficiente de las estructuras hidráulicas tales como compuertas, diques y esclusas, y para ello se deriva un modelado del sistema orientado a control, basado en un modelo simplificado ya existente, obtenido a partir de las ecuaciones de Saint-Venant. Esta nueva representación reduce la complejidad del modelo original, proporciona flexibilidad y permite coordinar información actual y retardada de forma sistemática. Sin embargo, la formulación resultante pertenece a la clase de sistemas descriptores con retardos, para los cuales las técnicas de control y de estimación de estado estándares necesitan ser extendidas. En cambio, el control predictivo basado en modelos y la estimación de estado con horizonte deslizante pueden ser fácilmente adaptadas para la formulación propuesta, además de permitir lidiar con restricciones físicas y operacionales de forma natural. Hay que tener en cuenta que, debido a las grandes dimensiones de las vías de navegación interior, una implementación centralizada no es, a menudo, ni posible ni deseada, y para paliar este problema se consideran los enfoques no centralizados. De este modo, se descompone el sistema global en subsistemas y se distribuye la carga computacional del problema centralizado entre los agentes locales, de manera que cada uno de ellos se encarga de cumplir los objetivos locales. Como las vías de navegación interior son sistemas fuertemente conectados, se sigue un enfoque distribuido, incluyendo un protocolo de comunicación entre los agentes. También se ha de considerar que la estimación de estado sólo será efectiva a condición de que los sensores provean información fiable. Asimismo, las acciones de control únicamente se podrán aplicar correctamente si los actuadores no están afectados por fallas. En efecto, cualquier avería puede conducir a una gestión ineficaz del sistema. Es por ello que la última parte de la tesis trata sobre el diseño de estrategias de supervisión que permitan detectar y aislar fallas en vías de navegación interior. Todos los resultados de modelado, control y estimación de estado centralizados y distribuidos, así como de diagnóstico de fallas, se aplican a un caso de estudio realista basado en las vías de navegación interior del norte de Francia para probar su eficacia.

Recently, there has been a significant rise in the Hyper-Text Transfer Protocol (HTTP) video streaming usage worldwide. However, the knowledge of performance of HTTP video streaming is still limited, especially in the aspect of factors which affect video quality. The reason is that HTTP video streaming has different characteristics from other video streaming systems. In this thesis, we show how the delivered quality of a Flash video playback is affected by different factors from diverse layers of the video delivery system, including congestion control algorithm, delay variation, playout buffer length, video bitrate and so on. We introduce Quality of Delivery Degradation (QoDD) then we use it to measure how much the Quality of Delivery (QoD) is degraded in terms of QoDD. The study is processed in a dedicated controlled environment, where we could alter the influential factors and then measure what is happening. After that, we use statistic method to analyze the data and find the relationships between influential factors and quality of video delivery which are expressed by mathematic models. The results show that the status and choices of factors have a significant impact on the QoD. By proper control of the factors, the quality of delivery could be improved. The improvements are approximately 24% by TCP memory size, 63% by congestion control algorithm, 30% by delay variation, 97% by delay when considering delay variation, 5% by loss and 92% by video bitrate.

We develop and evaluate two significant modeling concepts within the context of a large-scale Airspace Planning and Collaborative Decision-Making Model (APCDM) and, thereby, enhance its current functionality in support of both strategic and tactical level flight assessments. The first major concept is a new severe weather-modeling paradigm that can be used to assess existing tactical en route flight plan strategies such as the Flight Management System (FMS) as well as to provide rerouting strategies. The second major concept concerns modeling the mediated bartering of slot exchanges involving airline trade offers for arrival/departure slots at an arrival airport that is affected by the Ground Delay Program (GDP), while simultaneously considering issues related to sector workloads, airspace conflicts, as well as overall equity concerns among the airlines. This research effort is part of an $11.5B, 10-year, Federal Aviation Administration (FAA)-sponsored program to increase the U.S. National Airspace (NAS) capacity by 30 percent by the year 2010. Our innovative contributions of this research with respect to the severe weather rerouting include (a) the concept of â Probability-Netsâ and the development of discretized representations of various weather phenomena that affect aviation operations; (b) the integration of readily accessible severe weather probabilities from existing weather forecast data provided by the National Weather Service (NWS); (c) the generation of flight plans that circumvent severe weather phenomena with specified probability levels, and (d) a probabilistic delay assessment methodology for evaluating planned flight routes that might encounter potentially disruptive weather along its trajectory. Given a fixed set of reporting stations from the CONUS Model Output Statistics (MOS), we begin by constructing weather-specific probability-nets that are dynamic with respect to time and space. Essential to the construction of the probability-nets are the point-by-point forecast probabilities associated with MOS reporting sites throughout the United States. Connections between the MOS reporting sites form the strands within the probability-nets, and are constructed based upon a user-defined adjacency threshold, which is defined as the maximum allowable great circle distance between any such pair of sites. When a flight plan traverses through a probability-net, we extract probability data corresponding to the points where the flight plan and the probability-net strand(s) intersect. The ability to quickly extract this trajectory-related probability data is critical to our weather-based rerouting concepts and the derived expected delay and related cost computations in support of the decision-making process. Next, we consider the superimposition of a flight-trajectory-grid network upon the probability-nets. Using the U.S. Navigational Aids (Navaids) as the network nodes, we develop an approach to generate flight plans that can circumvent severe weather phenomena with specified probability levels based on determining restricted, time-dependent shortest paths between the origin and destination airports. By generating alternative flight plans pertaining to specified threshold strand probabilities, we prescribe a methodology for computing appropriate expected weather delays and related disruption factors for inclusion within the APCDM model. We conclude our severe weather-modeling research by conducting an economic benefit analysis using a k-means clustering mechanism in concert with our delay assessment methodology in order to evaluate delay costs and system disruptions associated with variations in probability-net refinement-based information. As a flight passes through the probability-net(s), we can generate a probability-footprint that acts as a record of the strand intersections and the associated probabilities from origin to destination. A flight planâ s probability-footprint will differ for each level of data refinement, from whence we construct route-dependent scenarios and, subsequently, compute expected weather delay costs for each scenario for comparative purposes. Our second major contribution is the development of a novel slot-exchange modeling concept within the APCDM model that incorporates various practical issues pertaining to the Ground Delay Program (GDP), a principal feature in the FAAâ s adoption of the Collaborative Decision-Making (CDM) paradigm. The key ideas introduced here include innovative model formulations and several new equity concepts that examine the impact of â at-least, at-mostâ trade offers on the entire mix of resulting flight plans from respective origins to destinations, while focusing on achieving defined measures of â fairnessâ with respect to the selected slot exchanges. The idea is to permit airlines to barter assigned slots at airports affected by the Ground Delay Program to their mutual advantage, with the FAA acting as a mediator, while being cognizant of the overall effect of the resulting mix of flight plans on air traffic control sector workloads, collision risk and safety, and equity considerations. We start by developing two separate slot-exchange approaches. The first consists of an external approach in which we formulate a model for generating a set of package-deals, where each package-deal represents a potential slot-exchange solution. These package-deals are then embedded within the APCDM model. We further tighten the model representation using maximal clique cover-based cuts that relate to the joint compatibility among the individual package-deals. The second approach significantly improves the overall model efficiency by automatically generating package-deals as required within the APCDM model itself. The model output prescribes a set of equitable flight plans based on admissible trades and exchanges of assigned slots, which are in addition conformant with sector workload capabilities and conflict risk restrictions. The net reduction in passenger-minutes of delay for each airline is the primary metric used to assess and compare model solutions. Appropriate constraints are included in the model to ensure that the generated slot exchanges induce nonnegative values of this realized net reduction for each airline. In keeping with the spirit of the FAAâ s CDM initiative, we next propose four alternative equity methods that are predicated on different specified performance ratios and related efficiency functions. These four methods respectively address equity with respect to slot-exchange-related measures such as total average delay, net delay savings, proportion of acceptable moves, and suitable value function realizations. For our computational experiments, we constructed several scenarios using real data obtained from the FAA based on the Enhanced Traffic Management System (ETMS) flight information pertaining to the Miami and Jacksonville Air Route Traffic Control Centers (ARTCC). Through our experimentation, we provide insights into the effect of the different proposed modeling concepts and study the sensitivity with respect to certain key parameters. In particular, we compare the alternative proposed equity formulations by evaluating their corresponding slot-exchange solutions with respect to the net reduction in passenger-minutes of delay for each airline. Additionally, we evaluate and compare the computational-effort performance, under both time limits and optimality thresholds, for each equity method in order to assess the efficiency of the model. The four slot-exchange-based equity formulations, in conjunction with the internal slot-exchange mechanisms, demonstrate significant net savings in computational effort ranging from 25% to 86% over the original APCDM model equity formulation. The model has been implemented using Microsoft Visual C++ and evaluated using a C++ interface with CPLEX 9.0. The overall results indicate that the proposed modeling concepts offer viable tools that can be used by the FAA in a timely fashion for both tactical purposes, as well as for exploring various strategic issues such as air traffic control policy evaluations; dynamic airspace resectorization strategies as a function of severe weather probabilities; and flight plan generation in response to various disruption scenarios.
Ph. D.

碩士
國立成功大學
資訊工程學系碩博士班
95
Delay control is an important service which belongs to Diffserv on Internet. Traditionally, mechanisms for delay control, like PAD scheduling, WTP scheduling, and HPD scheduling, are all deployed in IP layer and only offer a ratio of delay time for different applications. These mechanisms can not precisely control delay for a certain queuing delay request. Thus, in order to offer an accurate delay control service, we present DCA-FTCP, a delay control mechanism based on FAST TCP, in this thesis. On the basis of TCP layer, the proposed DCA-FTCP is easy to be installed in end hosts rather than current DiffServ mechanisms which need extra support from routers. And by mathematical analysis, DCA-FTCP is proven with its effectiveness of absolutely precise delay control service. Furthermore, a series of simulations are also conducted to verify the performance of DCA-FTCP. DCA-FTCP can indeed offer an absolutely accurate delay control service for Internet transmission.

碩士
國立臺灣科技大學
電機工程系
92
Generally, traffic signal can be controlled by two kinds of approaches, timer signal traffic control and dynamic calculation traffic control. Timer signal traffic control is a timer-schedule model, which is to pre-define signal schedules for each day. In this kind of approaches, there are usually several pre-set schedules which are used in different time slots in a day. Dynamic calculation traffic control is to dynamically tune the traffic control strategy based on some observed information, such as traffic flow or traffic density. Usually this kind of approaches needs to collect information every 10~15 minutes so that it can predicts traffic in the future. In timer signal traffic control, many scholars such as Webster, Akcelik, etc., have proposed various approaches. In dynamic calculation traffic control, there also exist several mature models as the OPAC mode, the MOVA mode, etc. In this thesis, we model traffic signal control based on Akcelik’s delay model. We use a simple genetic algorithm to find the optimal valid period. We then analyze the relationship between flow and the obtained valid period to discover any possible ways of dynamic calculation traffic control. We also study the effects of different powers of the delay time used in the fitness function value. It is found that it can have a smaller delay time with a better safe velocity when the power of the delay time is 2. We also analyze the relationship between traffic flow and the valid signal control period. It is concluded from our simulation that the dynamic control rules can be modeled as a curve as the difference between the maximal x-coordinate flow and the maximal y-coordinate flow vs. the difference between the maximal x-coordinate valid period and the maximal y-coordinate valid period. It can be verified that the total delay time based on the obtained curve is smaller than that of using the original timer signal traffic control.

Power control is essential in Code Division Multiple Access (CDMA) systems in order to reduce the near-far effect, optimize,the system capacity, and combat the signal degradation due to fading. One problem with Closed Loop Power Control (CLPC) is the delay introduced by power measurement and round-trip delay in the power control loop. We study the impact of power control loop delays on Frame Error Rate (FER) performance under a range of channel conditions. A new CLPC algorithm with delay compensation and fade prediction is then proposed to mitigate the effects of loop delays on CLPC. Delay compensation can reduce power oscillation amplitude around the desired received power level and fade prediction can forecast an upcoming fade in order to mitigate its effect. The FER performance on the forward link of an Interim Standard - 2000 (IS-2000) CDMA system using the delay compensated fade prediction based CLPC algorithm is studied. Simulations with a detailed IS-2000 physical layer model and various Third Generation Partnership Project 2 (3GPP2) channel models are used to illustrate the performance gains of the proposed CLPC algorithm over the conventional CLPC algorithm. The performance of the proposed CLPC algorithm as a function of mobile speed, delay, and carrier frequency is analyzed. It is found that the proposed CLPC algorithm performs better than the conventional CLPC algorithm by about 1 dB for a range of mobile speeds of interest. The performance improvement obtainable by using the proposed CLPC algorithm can reduce the interference and result in an increase in the system capacity. Finally, the effect of power control bit (PCB) errors on the performance of the proposed CLPC algorithm is studied. Simulation results indicate that the proposed CLPC algorithm is still beneficial when the PCB error rate is 5%.

博士
國立交通大學
資訊工程學系
84
The advance of high speed network technology has enabled the development of the multimedia communication systems supporting all conceivable media including voice, video, and data. For transporting such a diverse mix of traffic sources requiring different Quality Of Services (QOSs), multimedia communication systems consisting of the underlying networks and the end systems are demanded to provide QOS guarantees for different classes of traffic sources. This thesis aims at providing delay- basedQOS control mechanisms for multimedia communications through ATM networks. First, regarding the Earliest-Due-Date (EDD) as one of the most promising scheduling disciplines providing QOS guarantees in wide area ATM Networks, we propose a feasible implementation architecture and in-depth performance analysis for the realization ofthe EDD scheduling discipline. Second, while the underlying network provides the end-to-end delay guarantees for multimedia communications, resolutions of networkdelay jitters in end systems supporting diverse multimedia applications are highly essential. In particular, multimedia communications supporting multimedia data in high speed networks often require the smoothing of video playout to prevent potential playout discontinuity while still achieving satisfactory playout quality. To satisfy this need, in this thesis, we propose a novel video playout smoothing mechanism, called the Video Smoother, in receiving end systems to guarantee acceptable playout quality for real-time video applications.

碩士
國立交通大學
機械工程學系
98
This thesis presents a predictive disturbance observer for two-input-two-output (TITO) stable systems with input delay and output delay. The controlling method proposed here incorporates a decoupler in the forward loop to compensate model coupling, which makes the complicated TITO system solvable as two simple SISO (single-input-single-output) systems. For the disturbance rejection, the concept of predictive control is used based on the characteristic of deterministic disturbances to eliminate time delay effect, hence the proposed scheme can obtain better disturbance rejection. Predictive disturbance observer (PDOB) can improve the performance of time delay system and reject various forms of deterministic disturbance, including the step, ramp and sinusoidal disturbance. The scheme can separate design controller for set-point tacking and for disturbance rejection with a predictive disturbance observer for two-input-two-output (TITO) stable systems with input delay and output delay. Internal stability and robustness of the proposed closed-loop system are analyzed. When the system exist the uncertainty, robust stability and disturbance rejection of the system are discussed in the simulation.

博士
國立成功大學
電機工程學系
90
This dissertation is dedicated to develop the optimal tracking control of hybrid time-delay nominal/uncertain systems. It includes the following distributions: (i) The optimal digital tracking design for sampled-data time-delay systems under state and control constraints is proposed. The advanced digital redesign technique based on the multi-objective evolutionary programming (MOEP) is effective to achieve performance optimization under concurrent system constraints. (ii) The tracking control of cascaded hybrid systems with different input time delays is developed. First, the optimal high-gain analog tracker is designed based on the MOEP optimal search technique, then utilizing the MOEP-based digital redesign approach to determine the relative long sampling period under constraints and associated implementable low-gain digital controller for the hybrid systems. (iii) Considering the uncertainties and restrictions in time-invariant linear systems, an optimal min-max algorithm to minimize the worst errors between the outputs and the desired signals is proposed. (iv) A new digital modeling technique involving the Newton’s forward difference formula with EP for sampled-data uncertain systems with general multiple state and input delays is developed. Furthermore, combining the successful digital redesign technology with the MOEP via the min-max method, the best digital tracker is also developed. MOEP-based optimal digital redesign techniques are utilized in this dissertation to develop digital controllers for hybrid nominal/uncertain systems. The effectiveness of developed digital control laws is demonstrated by illustrative examples. To believe firmly, the advantages of this dissertation are helpful to complete the theories and implements in the literature for optimal control of hybrid time-delayed systems.

碩士
逢甲大學
電子工程所
99
In this thesis, novel observer-based adaptive interval type-2 fuzzy control (AIT2FC) is proposed to handle high level uncertainties such as uncertainties in inputs to the FLC, uncertainties in control outputs, linguistic uncertainties and uncertainties associated with the noisy training data facing the fuzzy logic controller (FLC) in dynamic nonlinear systems with time delay which is a source of instability. Three adaptive fuzzy neural network (FNN) control schemes are included：direct FNN, indirect FNN and hybrid FNN. Based on approach learning algorithm, free parameters of the AIT2FC can be tuned on line by output feedback control law and adaptive law by using Lyapunov criterion. During the design procedure, not only the stability and robustness can be guaranteed but also the external disturbance on the tracking error can be attenuated. The numerical simulation is performed to illustrate the effectiveness of the proposed control strategy. Furthermore, simulation results show that interval type-2 FLCs have the potential to overcome the limitations of type-1 FLCs can improve design performance in many application involving high levels of uncertainty.

The objective of this research is to develop distributed approaches to optimizing network traffic. Two problems are studied, which include exploiting social networks in routing packets (coupons) to desired network nodes (users in the social network), and developing a rate based transport protocol, which will guarantee that all the flows in a network (e.g. Internet) meet a delay constraint per packet. Firstly, we will study social networks as a means of obtaining information about a system. They are increasingly seen as a means of obtaining awareness of user preferences. Such awareness could be used to target goods and services at them. We consider a general user model, wherein users could buy different numbers of goods at a marked and at a discounted price. Our first objective is to learn which users would be interested in a particular good. Second, we would like to know how much to discount these users such that the entire demand is realized, but not so much that profits are decreased. We develop algorithms for multihop forwarding of such discount coupons over an online social network, in which users forward coupons to each other in return for a reward. Coupling this idea with the implicit learning associated with backpressure routing (originally developed for multihop wireless networks), we would like to demonstrate how to realize optimal revenue. We will then propose a simpler heuristic algorithm and try to show, using simulations, that its performance approaches that of backpressure routing. As the second problem, we look at the traditional formulation of the total value of information transfer, which is a multi-commodity flow problem. Here, each data source is seen as generating a commodity along a fixed route, and the objective is to maximize the total system throughput under some concept of fairness, subject to capacity constraints of the links used. This problem is well studied under the framework of network utility maximization and has led to several different distributed congestion control schemes. However, this idea of value does not capture the fact that flows might associate value, not just with throughput, but with link-quality metrics such as packet delay, jitter and so on. The traditional congestion control problem is redefined to include individual source preferences. It is assumed that degradation in link quality seen by a flow adds up on the links it traverses, and the total utility is maximized in such a way that the quality degradation seen by each source is bounded by a value that it declares. Decoupling source-dissatisfaction and link-degradation through an ?effective capacity? variable, a distributed and provably optimal resource allocation algorithm is designed, to maximize system utility subject to these quality constraints. The applicability of our controller in different situations is illustrated, and results are supported through numerical examples.

碩士
國立成功大學
機械工程學系
102
Robotic control systems have been extensively applied in industrial operation, underwater navigation, and outer space exploration. With the rapid development of Internet, traditional robotic systems with wired connection are increasingly replaced by systems in which the robotic system and controller are connected through a communication network. Control of robotic system over communication network provides many advantage, but the signal transmission cannot be regarded as ideal, and network uncertainties time delay, packet loss, and limited communication resources constitute major challenges. The objective of this study is to develop a control algorithm for network of robotic systems achieve position regulation in the presence of communication delay and packet loss. This thesis studies the control problem of networked robotic system by utilizing passivity approach. Wave-Variable Transformation is combined with Wave-Variable Modulation to deal with networked robotic systems under time-constant delay and packet loss. Based on passivity control theory, robotic system is passive with respect to velocity and torque as the input-output pair. Therefore the remote controller works out with the position information by integrating the velocity information. The issue of position drift would degrade performance of a robotic system due to the lack of position information in remote controller. In this thesis, a Local Controller is presented to transmit a signal containing both velocity and position information. Therefore, the position regulation can be guaranteed without the requirement of explicit position signals. Due to the discrete-time nature of communication network, the proposed control framework is extended to discrete-time system. A passive sampler and hold is used to convert the continuous-time signal form the robotic system to a discrete-time signal, and vice versa. Finally, the efficiency of the developed networked robotic system is validated via both simulation and experiment results.

碩士
國立交通大學
機械工程系所
97
The purpose of this thesis is to use the design of the predictive disturbance observer for a class of delayed systems. Since time delay exists in many industrial processes, there are many time delay compensation methods. However most of the compensation methods can not attenuate disturbance effectively, especially for periodic disturbances. In this thesis, the concept of predictive control is utilized based on the characteristic of deterministic disturbances to eliminate time delay effect, hence the proposed design achieves better disturbance rejection which not only applies to step and ramp disturbances but also to periodic disturbances as well. This advantage is applied to SISO (single-input-single-output) unstable non-minimum phase delayed systems and TITO (two-input-two-output) stable delayed systems. Both proposed schemes have two degree of freedom in designing controllers for setpoint tracking and disturbance rejection respectively. Internal stability and robustness of the proposed closed-loop system are analyzed. Performances are compared via several examples in the case of nominal model and perturbed model, subjected to step, ramp and periodic disturbances.

碩士
淡江大學
航空太空工程學系碩士班
100
This paper investigates the development of a distributed multi-microcontroller flight control system for an in-house designed UAV. The flight control computer and other avionic systems and instruments are connected over an I2C (inter-integrated circuit) data bus with the flight control computer as the master micro-controller. The system forms a networked control system. Time delay problem is inevitable when information is transmitted between the micro-controllers. A model-based state feedback flight control system with time delay is presented in the paper. The plant model is used to simulate the plant behavior during the periods when sensor data are not available. When the controller receives the sensor data that were transmitted by the sensor a period of time ago, a propagation unit is employed in the control system to propagate the sensor signals instantaneously to the present time. The estimate is then used to update the model that in turn will generate the control signal for the plant. Computer simulation confirms the success of the model-based design for the distributed multi-chips flight control system.

碩士
國立中正大學
通訊工程研究所
107
In recent years, machine learning、cloud calculation and internet of things has played an important role in our society. For these technologies, internet protocols is the key part of them. When the among of data transfer in the internet is increase drastically,a suitable TCP congestion control mechanism is needed.In this paper, a new TCP congestion control mechanism based on BDP will be proposed.

博士
國立高雄第一科技大學
工程科技研究所
96
In this dissertation, the orthogonal-functions approach (OFA) is first proposed to solve the Takagi-Sugeno (TS) fuzzy-model-based time-delay dynamic equations. The new method simplifies the procedure of solving the TS-fuzzy-model-based time-delay dynamic equations (TSFMTDE) into the successive solution of a system of recursive formulae only involving the matrix algebra. The new proposed approach is non-iterative, non-differential, non-integral, straightforward, and well-adapted to the computer implementation. The computational complexity can therefore be reduced remarkably. An illustrated numerical example is given in order to demonstrate the availability of the presently proposed method. Next, for the finite-horizon optimal control problem of the TS-fuzzy-model-based time-delay control systems, by integrating the delay-dependent stabilizability condition, the OFA, and the hybrid Taguchi-genetic algorithm (HTGA), an integrative method is presented to design the stable and quadratic-optimal parallel-distributed-compensation (PDC) controllers. In this dissertation, the delay-dependent stabilizability condition is proposed in terms of linear matrix inequalities (LMIs). The control objective of quadratic optimal fuzzy PDC controllers is to minimize a quadratic integral performance index, where the quadratic integral performance index is also converted into the algebraic form by using the OFA. Based on the OFA, the stable and quadratic-optimal PDC control problem for the TS-fuzzy-model-based time-delay control systems is replaced by a static parameter optimization problem represented by the algebraic equations with constraint of LMI-based stabilizability condition; thus greatly simplifying the stable and optimal PDC control design problem. The computational complexity for both differential and integral in the stable and optimal PDC control design of the original dynamic systems may therefore be reduced considerably. Then, for the static constrained-optimization problem, the HTGA is employed to find the stable and quadratic-optimal PDC controllers of the TS-fuzzy-model-based time-delay control systems. A design example of the stable and quadratic-optimal PDC controllers is given to demonstrate the applicability of the proposed approach. Finally, for the finite-horizon optimal control problem of a class of time-varying TS-fuzzy-model-based time-delay control systems, by complementarily fusing the OFA, the HTGA and the delay-dependent stabilizability condition, an integrative method is presented to design the stable and quadratic-optimal PDC controllers, where the delay-dependent stabilizability condition can be derived from the concept of convex sets and the LMI technique. A design example of the stable and quadratic-optimal PDC controllers of a class of the time-varying TS-fuzzy-model-based time-delay control systems is given to demonstrate the applicability of the proposed new integrative approach.

碩士
國立臺北科技大學
電機工程系研究所
102
In networked control systems (NCSs), Internet serves as the transmission medium for control command and feedback command. Therefore, the transmission medium causes NCSs also lead to unavoidable problems in time delays which seriously degrade control performance and stability. Among existing time delay compensation methods, PID controller is designed to be simple, but it is difficult to have excellent control for time delay varied system. To improve time delay varied system, this project use fuzzy logic controller to replaced PID controller. Thus, such approach can enhance control adaptability and avoid complex mathematical models. When time delay varied is great, the fuzzy rules which are based on the experience of human operators and fixed type can’t be adaptive improvements. Therefore, it is critical for NCSs to be able to make transient responses and maintain steady state responses within a great time delay varied. This study proposed a NCSs design. The method can keep the system responses for time delay varied system. This study verified the result of simulation and practical experiment. The practical experiment implemented into two parts. In the first approach, on-line estimation of the time delay is developed by network monitor interface processing measurement of the round-trip time between packages. Thereby, compare of time delay difference in proximal and remote. The second approach proposed a control architecture where CDOB is the basis for time delay varied system. CDOB appears oscillations in the transient response. Therefore, multi-level fuzzy controller (MLFC) is selected as base of control response. The first layer fuzzy control rules and generated based on the experience of human operators. In order to correct the impreciseness of the first layer fuzzy control rules and compensate for system response. A second layer fuzzy controller is used to tune the output membership functions and fixed the center of control response. A systematic procedure is proposed for design of a multi-level fuzzy controller, which is capable of controlling nonlinear systems with uncertainties and time delay varied parameter to reduce overshoot and improve system performance.

碩士
大同大學
電機工程學系(所)
103
In this thesis, an observer-based fuzzy sliding mode control approach for uncertain underactuated nonlinear systems with time delay is proposed. This study deals with the problem of controlling a class of uncertain nonlinear systems in the presence of the state time delay. The fuzzy logic systems are used to approximate the unknown nonlinear functions by some adaptive laws, and a fuzzy state observer is employed to estimate the unmeasured states. A stability criterion in terms of Lyapunov-Krasovskii functional method is derived to guarantee the stability of uncertain underactuated nonlinear systems with state time delay. From Lyapunov stability theorem, the proposed design approach can not only guarantee semi-globally uniformly ultimately boundedness of all the signals in the closed-loop system, but also converge to a small neighborhood of the origin for the tracking error of the system. Finally, the simulation results are given to show the effectiveness of the proposed control approach.