Networked Control Systems: The Communication Basics and Control Methodologies

As an emerging research field, networked control systems have shown the increasing importance and attracted more and more attention in the recent years. The integration of control and communication in networked control systems has made the design and analysis of such systems a great theoretical challenge for conventional control theory. Such an integration also makes the implementation of networked control systems a necessary intermediate step towards the final convergence of control, communication, and computation. We here introduce the basics of networked control systems and then describe the state-of-the-art research in this field. We hope such a brief tutorial can be useful to inspire further development of networked control systems in both theory and potential applications

Discrete Time Systems

Discrete-Time Systems comprehend an important and broad research field. The consolidation of digital-based computational means in the present, pushes a technological tool into the field with a tremendous impact in areas like Control, Signal Processing, Communications, System Modelling and related Applications. This book attempts to give a scope in the wide area of Discrete-Time Systems. Their contents are grouped conveniently in sections according to significant areas, namely Filtering, Fixed and Adaptive Control Systems, Stability Problems and Miscellaneous Applications. We think that the contribution of the book enlarges the field of the Discrete-Time Systems with signification in the present state-of-the-art. Despite the vertiginous advance in the field, we also believe that the topics described here allow us also to look through some main tendencies in the next years in the research area

Optimal Control of Systems with Delayed Observation Sharing Patterns

Coordinated Science Laboratory was formerly known as Control Systems LaboratoryNational Science Foundatio

Distributed optimal and predictive control methods for networks of dynamic systems

Several recent approaches to distributed control design over networks of interconnected dynamic systems rely on certain assumptions, such as identical subsystem dynamics, absence of dynamical couplings, linear dynamics and undirected interaction schemes. In this thesis, we investigate systematic methods for relaxing a number of simplifying factors leading to a unifying approach for solving general distributed-control stabilization problems of networks of dynamic agents. We show that the gain-margin property of LQR control holds for complex multiplicative input perturbations and a generic symmetric positive definite input weighting matrix. Proving also that the potentially non-simple structure of the Laplacian matrix can be neglected for stability analysis and control design, we extend two well-known distributed LQR-based control methods originally established for undirected networks of identical linear systems, to the directed case. We then propose a distributed feedback method for tackling large-scale regulation problems of a general class of interconnected non-identical dynamic agents with undirected and directed topology. In particular, we assume that local agents share a minimal set of structural properties, such as input dimension, state dimension and controllability indices. Our approach relies on the solution of certain model matching type problems using local linear state-feedback and input matrix transformations which map the agent dynamics to a target system, selected to minimize the joint control effort of the local feedback-control schemes. By adapting well-established distributed LQR control design methodologies to our framework, the stabilization problem of a network of non-identical dynamical agents is solved. We thereafter consider a networked scheme synthesized by multiple agents with nonlinear dynamics. Assuming that agents are feedback linearizable in a neighborhood near their equilibrium points, we propose a nonlinear model matching control design for stabilizing networks of multiple heterogeneous nonlinear agents. Motivated by the structure of a large-scale LQR optimal problem, we propose a stabilizing distributed state-feedback controller for networks of identical dynamically coupled linear agents. First, a fully centralized controller is designed which is subsequently substituted by a distributed state-feedback gain with sparse structure. The control scheme is obtained byoptimizing an LQR performance index with a tuning parameter utilized to emphasize/deemphasize relative state difference between coupled systems. Sufficient conditions for stability of the proposed scheme are derived based on the inertia of a convex combination of two Hurwitz matrices. An extended simulation study involving distributed load frequency control design of a multi-area power network, illustrates the applicability of the proposed method. Finally, we propose a fully distributed consensus-based model matching scheme adapted to a model predictive control setting for tackling a structured receding horizon regulation problem

Cooperative Estimation and Control of Large-scale Process Networks

학위논문 (박사)-- 서울대학교 대학원 : 화학생물공학부, 2017. 2. 이종민.본 연구는 대규모 공정 네트워크의 협동 추정 및 제어에 관한 연구이며 기존 대규모 공정의 추정 및 제어 알고리즘의 단점을 보완한 새로운 알고리즘을 제안한다. 또한 대규모 시스템의 한 가지 예로 주로 대규모 상수관망을 대상으로 하여 모델링 및 추정을 통해 이상 진단 및 감지 알고리즘을 개발한다. 상수관망에서 누수, 파열 등의 이상이 발생할 경우 시스템의 크기 및 복잡성으로 인해 이를 감지 및 진단하는 것이 매우 어렵다. 또한 상수관망의 이상으로 인해 발생한 압력 전파 모델이 존재하지 않기 때문에 시스템 모델 없이 효과적으로 이상감지 및 진단하는 기법을 제안하고자 하였다. 기존에 화학공정에서 이상감지를 위해 많이 쓰이는 통계적 기법인 cumulative sum(CUSUM)과 특이점을 빠르고 정확하게 감지할 수 있는 discrete wavelet transform(DWT)을 통합한 새로운 감지 알고리즘을 제안하였고, 이상감지 결과를 이용하여 대규모 상수관망에서 간단한 최적화 해법으로 이상의 위치를 진단하는 알고리즘을 제안하였다. 실제 상수관망의 이상 실험 데이터를 사용하여 제안된 알고리즘을 검증하였고 진단 오차가 30 m 이내로 기존 기술 대비 이상 진단 오차를 현저히 줄임을 확인하였다. 상수관망의 압력 전파 모델이 존재한다면 상태추정(state estimation)을 이용하여 데이터 기반의 알고리즘에 비해 쉽고 빠르게 이상감지 및 진단을 할 수 있기 때문에 상수관망의 이상으로 인한 압력 전파 모델을 개발하고자 하였다. 모델링을 위해 consensus 알고리즘이라는, 네트워크에서의 노드 간의 상태(state)를 나타내는 알고리즘을 이용하였고 consensus 알고리즘을 상수관망에 맞게 수정하여 복잡한 압력 전파 모델을 선형의 간단한 형태로 나타낼 수 있었다. 이를 실제 실험 데이터와 비교하여 제안한 consensus 알고리즘 기반 모델이 실제 압력 전파 다이나믹스를 15% 이내의 오차로 나타낼 수 있음을 보였다. 다음으로 위에서 개발한 모델을 이용하여 대규모 네트워크 시스템에서의 상태추정 기법을 적용한 새로운 이상 감지 및 진단 알고리즘을 제안하였다. 기존의 칼만필터(Kalman filter) 등의 상태추정 방법은 상수관망과 같은 대규모 시스템에 적용될 경우 시스템의 규모가 매우 크기 때문에 계산량 등의 문제가 발생한다. 이를 해결하기 위해 전체 시스템을 여러 개의 서브시스템으로 나눈 decentralized 추정 방법이 연구가 되었다. 그러나 이는 서브시스템 간 상호작용을 고려하지 않기 때문에 이를 보완하기 위해 distributed 추정이 연구되었지만 이 방식은 전체 시스템의 크기가 커짐에 따라서 서브시스템의 estimator의 크기 또한 커지는, 즉 scalability가 없다는 단점이 있다. 본 연구에서 이러한 기존의 방법들을 보완한 새로운 cooperative estimation 알고리즘을 제안하였다. Cooperative state estimation을 상수관망 뿐만 아니라 대규모 화학공정에도 적용하여 decentralized 그리고 distributed 방식의 단점을 보완하면서 centralized estimation과 유사한 성능을 가짐을 보였다. 마지막으로, cooperative estimation 개발에 사용한 핵심 아이디어를 제어 알고리즘에 똑같이 적용하여 cooperative model predictive control(cooperative MPC)을 제안하였다. Cooperative MPC 또한 대규모 공정 네트워크의 제어에 있어 기존의 decentralized 또는 distributed MPC의 단점을 보완하는 새로운 알고리즘으로, 대규모 화학공정에 적용하여 centralized MPC와 유사한 성능을 보임을 증명하였다. 본 박사 논문에서 제시한 대규모 공정의 추정 및 제어를 위한 cooperative KF 그리고 cooperative MPC를 사용하여 기존의 centralized의 계산량 문제, decentralized의 상호작용 문제, 그리고 distributed의 scalability 문제를 해결한 새로운 추정 및 제어가 가능하다.State estimation and control of large-scale process network systems are considered as difficult problems because they consist of numerous subsystems and interactions between subsystems make the entire network dynamics complicated. Chemical processes and pipe networks are representative large-scale networks. In this thesis, we propose a novel cooperative estimation and control algorithms of large-scale process networks. In water pipe networks, a fault such as pipe leak or burst often happens and it is difficult to detect and diagnose. For fault detection and location of water pipe networks, state estimation can be an effective tool. However, a mathematical model describing dynamics of leak in water pipe networks does not exist. Before we develop a mathematical model of water pipe network, we propose a novel methodology to detect and locate leak in water pipe networks. Conventional detection methods include a cumulative sum (CUSUM) and a wavelet transform (WT). However, the CUSUM has a problem of slow response and the WT is sensitive to signal transitions. We integrate two algorithms to effectively detect sudden pressure changes of water pipe networks. The developed leak detection and location system is validated with real field data obtained from artificial leaks by opening hydrant valves in small-scale and medium-scale pipe networks and natural leak occurred in large-scale pipe network. The developed algorithm is model-free approach to detection and location of leak in water pipe networks. We propose consensus algorithm based mathematical model of leak dynamics. Modeling the flow dynamics of leaks in water pipe networks is an extremely difficult problem due to the complex entangled network structure and hydraulic phenomenon. We propose a fundamental model for negative pressure wave dynamics of leaks in water pipe networks based on a consensus algorithm and water hammer theory. The resulting model is a simple and linearly interconnected model in the network even though the dynamics of water pipe networks has a considerable complexity. The model is then validated using experimental data obtained from a real water pipe network. A comparative study demonstrates that the proposed model can describe the real system with high qualitative and quantitative accuracy and that it can be used to develop a model-based leak detection and location algorithm based on the state estimation approach. Using the developed model, we develop a fault detection and location algorithm based on state estimation in water pipe networks. The detection algorithm is based on cooperative H∞-estimation for large-scale interconnected linear systems. To show applicability of the proposed model, we apply distributed and cooperative estimation with H∞-performance to the developed model. The estimation result demonstrates the consensus algorithm based pipe network model can be potentially used for leak detection and location with state estimation method. H∞-based design provides guaranteed performance with respect to model and measurement disturbances. Also, we propose cooperative Kalman filter of large-scale network systems. Basic concepts are based on cooperative H∞-estimation used for detection and location. The proposed cooperative Kalman filter can show fully decentralized or fully distributed state estimation performance depending on parameter selection. It is demonstrated using large-scale chemical process network. We finally propose a cooperative model predictive control of large-scale process networks based on the same concepts and ideas used to develop cooperative state estimation. Important properties of stability, optimality, local controllability, and scalability are also proved. When the developed cooperative MPC is applied to chemical process network composed of three process units, it shows performance between decentralized and distributed manners. We also show that the proposed cooperative MPC is the same with centralized MPC under certain condition.1. Introduction 1 1.1 Background and Motivation 1 1.2 Preliminaries 2 1.2.1 Network topology 3 1.2.2 Consensus algorithm 4 1.2.3 State Estimation for large-scale networks 6 1.2.4 Control for large-scale networks 9 1.3 Contribution 17 1.4 Outline 18 2. Model-free Approach to Fault Detection and Location of Water Pipe Networks 20 2.1 Introduction 20 2.2 Detection Algorithm 24 2.2.1 Noise filtering of raw pressure data 24 2.2.2 Cumulative sum for global detection 25 2.2.3 Discrete wavelet transform for local time correction 26 2.3 Location Algorithm 29 2.3.1 Negative pressure wave 29 2.3.2 Node matrix 31 2.3.3 Objective function 32 2.4 Integrated System 33 2.5 Experiments and Validations 34 2.5.1 Small-scale pipe network with artificial faults 34 2.5.2 Medium-scale pipe network with artificial faults 43 2.5.3 Large-scale pipe network with natural faults 46 2.6 Limitations for applicability to complex networks 52 2.7 Conclusions 53 3. Consensus Algorithm for Process Networks 54 3.1 Introduction 54 3.2 Consensus Algorithm based Process Network Model 59 3.2.1 Consensus in networks 59 3.3 Application to Water Pipe Networks 60 3.3.1 Flow dynamics based on consensus algorithm 61 3.3.2 Water hammer theory 62 3.3.3 Dynamics at leak point 64 3.3.4 Complete model 65 3.3.5 Experiment 66 3.3.6 Validation 69 3.4 Conclusions 74 4. Cooperative State Estimation of Large-scale Process Networks 77 4.1 Introduction 77 4.2 System Model and Repartition 79 4.2.1 System model 79 4.2.2 Repartition of system model 82 4.3 Cooperative State Estimation Based on Kalman Filter 84 4.3.1 Standard Kalman filter 84 4.3.2 Cooperative Kalman filter 87 4.4 Application I: Water Pipe Networks for Fault Detection and Location 98 4.5 Application II: Chemical Process Networks with Recycles 104 4.5.1 Network model 104 4.5.2 Simulation results 109 4.6 Conclusions 109 5. Cooperative Model Predictive Control of Large-scale Process Networks 112 5.1 Introduction 113 5.2 System Model and Repartition 115 5.3 Cooperative Model Predictive Control 116 5.3.1 Centralized MPC 116 5.3.2 Cooperative MPC 120 5.4 Application to Chemical Process Networks with Recycles 121 5.5 Conclusions 121 6. Concluding Remarks 123 6.1 Concluding Remarks 123 6.2 Future Directions 126 Bibliography 127 초록 138Docto

Nonlinear control and synchronization of multiple Lagrangian systems with application to tethered formation flight spacecraft

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 217-228).This dissertation focuses on the synchronization of multiple dynamical systems using contraction theory, with applications to cooperative control of multi-agent systems and synchronization of interconnected dynamics such as tethered formation flight. Inspired by stable combinations of biological systems, contraction nonlinear stability theory provides a systematic method to reduce arbitrarily complex systems into simpler elements. One application of oscillation synchronization is a fully decentralized nonlinear control law, which eliminates the need for any inter-satellite communications. We use contraction theory to prove that a nonlinear control law stabilizing a single-tethered spacecraft can also stabilize arbitrarily large circular arrays of tethered spacecraft, as well as a three-spacecraft inline configuration. The convergence result is global and exponential due to the nature of contraction analysis. The proposed decentralized control strategy is further extended to robust adaptive control in order to account for model uncertainties. Numerical simulations and experimental results validate the exponential stability of the tethered formation arrays by implementing a tracking control law derived from the reduced dynamics.(cont.) This thesis also presents a new synchronization framework that can be directly applied to cooperative control of autonomous aerospace vehicles and oscillation synchronization in robotic manipulation and locomotion. We construct a dynamical network of multiple Lagrangian systems by adding diffusive couplings to otherwise freely moving or flying vehicles. The proposed tracking control law synchronizes an arbitrary number of robots into a common trajectory with global exponential convergence. The proposed control law is much simpler than earlier work in terms of both the computational load and the required signals. Furthermore, in contrast with earlier work which used simple double integrator models, the proposed method permits highly nonlinear systems and is further extended to adaptive synchronization, partial-joint coupling, and concurrent synchronization. Another contribution of the dissertation is a novel nonlinear control approach for underactuated tethered formation flight spacecraft. This is motivated by a controllability analysis that indicates that both array resizing and spin-up are fully controllable by the reaction wheels and the tether motor. This work reports the first propellant-free underactuated control results for tethered formation flight.(cont.) We also fulfill the potential of the proposed strategy by providing a new momentum dumping method. This dissertation work has evolved based on the research philosophy of balancing theoretical work with practicality, aiming at physically intuitive algorithms that can be directly implemented in real systems. In order to validate the effectiveness of the decentralized control and estimation framework, a new suite of hardware has been designed and added to the SPHERES (Synchronize Position Hold Engage and Reorient Experimental Satellite) testbed. Such recent improvements described in this dissertation include a new tether reel mechanism, a force-torque sensor and an air-bearing carriage with a reaction wheel. This thesis also introduces a novel relative attitude estimator, in which a series of Kalman filters incorporate the gyro, force-torque sensor and ultrasound ranging measurements. The closed-loop control experiments can be viewed at ...by Soon-Jo Chung.Sc.D

MS FT-2-2 7 Orthogonal polynomials and quadrature: Theory, computation, and applications

Quadrature rules find many applications in science and engineering. Their analysis is a classical area of applied mathematics and continues to attract considerable attention. This seminar brings together speakers with expertise in a large variety of quadrature rules. It is the aim of the seminar to provide an overview of recent developments in the analysis of quadrature rules. The computation of error estimates and novel applications also are described

Generalized averaged Gaussian quadrature and applications

A simple numerical method for constructing the optimal generalized averaged Gaussian quadrature formulas will be presented. These formulas exist in many cases in which real positive GaussKronrod formulas do not exist, and can be used as an adequate alternative in order to estimate the error of a Gaussian rule. We also investigate the conditions under which the optimal averaged Gaussian quadrature formulas and their truncated variants are internal

Robust distributed control of constrained linear systems

This thesis presents new algorithms for the distributed control of a group of contrained, linear time-invariant (LTl) dynamic subsystems.EThOS - Electronic Theses Online ServiceGBUnited Kingdo