Wireless model-based predictive networked control system over cooperative wireless network

Owing to their distributed architecture, networked control systems (NCSs) are proven to be feasible in scenarios where a spatially distributed feedback control system is required. Traditionally, such NCSs operate over real-time wired networks. Recently, in order to achieve the utmost flexibility, scalability, ease of deployment, and maintainability, wireless networks such as IEEE 802.11 wireless local area networks (LANs) are being preferred over dedicated wired networks. However, conventional NCSs with event-triggered controllers and actuators cannot operate over such general purpose wireless networks since the stability of the system is compromised due to unbounded delays and unpredictable packet losses that are typical in the wireless medium. Approaching the wireless networked control problem from two perspectives, this work introduces a practical wireless NCS and an implementation of a cooperative medium access control protocol that work jointly to achieve decent control under severe impairments, such as unbounded delay, bursts of packet loss and ambient wireless traffic. The proposed system is evaluated on a dedicated test platform under numerous scenarios and significant performance gains are observed, making cooperative communications a strong candidate for improving the reliability of industrial wireless networks

Design implementation and analysis of wireless model based predictive networked control system over cooperative wireless network

Owing to their distributed architecture, networked control systems are proven to be feasible in scenarios where a spatially distributed control system is required. Traditionally, such networked control systems operate over real-time wired networks over which sensors, controllers and actuators interact with each other. Recently, in order to achieve the utmost flexibility, scalability, ease of deployment and maintainability, wireless networks such as IEEE 802.11 LANs are being preferred over dedicated wired networks. However, basic networked control systems cannot operate over such general purpose wireless networks since the stability of the system is compromised due to unbounded delays and unpredictable packet losses that are typical in the wireless medium. Approaching the wireless networked control problem from two perspectives, this thesis proposes a novel wireless networked control system and a realistic cooperative medium access control protocol implementation that work jointly to achieve decent control even under unbounded delay, bursts of packet loss and ambient wireless traffic. The proposed system is implemented and thoroughly evaluated on a dedicated test platform under numerous scenarios and is shown to be operational under bursts of packet loss and ambient wireless traffic levels which are intolerable for basic networked control systems while not being hindered by restraining assumptions of existing methods

El Control de sistemas ciberfísicos industriales. Revisión y primera aproximación.

Los sistemas ciberfísicos industriales (ICPS) abarcan las cuestiones de diseño, modelado y análisis de los sistemas ciberfísicos con especial énfasis en las aplicaciones industriales. El paradigma de la Industria 4.0 y las cuestiones asociadas a la transformación digital de la industria se pueden considerar un caso especial de ICPS. Uno de los pilares científico-técnicos para tratar el modelado y control de los ICPS es la inteligencia computacional y todos los métodos y técnicas agrupados dentro del control inteligente. En este trabajo se tratan algunos conceptos básicos de los ICPS, se presenta una aproximación a las principales estrategias de control utilizadas y algunas aplicaciones reportadas en la literatura

Hybrid Flocking Control Algorithm with Application to Coordination between Multiple Fixed-wing Aircraft

Flocking, as a collective behavior of a group, has been investigated in many areas, and in the recent decade, flocking algorithm design has gained a lot of attention due to its variety of potential applications. Although there are many applications exclusively related to fixed-wing aircraft, most of the theoretical works rarely consider these situations. The fixed-wing aircraft flocking is distinct from the general flocking problems by four practical concerns, which include the nonholonomic constraint, the limitation of speed, the collision avoidance and the efficient use of airspace. None of the existing works have addressed all these concerns. The major difficulty is to take into account the all four concerns simultaneously meanwhile having a relatively mild requirement on the initial states of aircraft. In this thesis, to solve the fixed-wing aircraft flocking problem, a supervisory decentralized control algorithm is proposed. The proposed control algorithm has a switching control structure, which basically includes three modes of control protocol and a state-dependent switching logic. Three modes of decentralized control protocol are designed based on the artificial potential field method, which helps to address the nonholonomic constraint, the limitation of speed and the collision avoidance for appropriate initial conditions. The switching logic is designed based on the invariance property induced by the control modes such that the desirable convergence properties of the flocking behavior and the efficient use of airspace are addressed. The proposed switching logic can avoid the fast mode switching, and the supervisor does not require to perform switchings frequently and respond to the aircraft immediately, which means the desired properties can still be guaranteed with the presence of the dwell time in the supervisor

STABILITY AND PERFORMANCE OF NETWORKED CONTROL SYSTEMS

Network control systems (NCSs), as one of the most active research areas, are arousing comprehensive concerns along with the rapid development of network. This dissertation mainly discusses the stability and performance of NCSs into the following two parts. In the first part, a new approach is proposed to reduce the data transmitted in networked control systems (NCSs) via model reduction method. Up to our best knowledge, we are the first to propose this new approach in the scientific and engineering society. The "unimportant" information of system states vector is truncated by balanced truncation method (BTM) before sending to the networked controller via network based on the balance property of the remote controlled plant controllability and observability. Then, the exponential stability condition of the truncated NCSs is derived via linear matrix inequality (LMI) forms. This method of data truncation can usually reduce the time delay and further improve the performance of the NCSs. In addition, all the above results are extended to the switched NCSs. The second part presents a new robust sliding mode control (SMC) method for general uncertain time-varying delay stochastic systems with structural uncertainties and the Brownian noise (Wiener process). The key features of the proposed method are to apply singular value decomposition (SVD) to all structural uncertainties, to introduce adjustable parameters for control design along with the SMC method, and new Lyapunov-type functional. Then, a less-conservative condition for robust stability and a new robust controller for the general uncertain stochastic systems are derived via linear matrix inequality (LMI) forms. The system states are able to reach the SMC switching surface as guaranteed in probability 1 by the proposed control rule. Furthermore, the novel Lyapunov-type functional for the uncertain stochastic systems is used to design a new robust control for the general case where the derivative of time-varying delay can be any bounded value (e.g., greater than one). It is theoretically proved that the conservatism of the proposed method is less than the previous methods. All theoretical proofs are presented in the dissertation. The simulations validate the correctness of the theoretical results and have better performance than the existing results

Modelo de perda de pacote para projeto e simulação de sistemas de controle em rede sem fio

Orientador : Prof. Dr. Eduardo Parente RibeiroDissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia Elétrica. Defesa: Curitiba, 12/05/2016Inclui referências : f. 61-63Área de concentração: Sistemas eletrônicosResumo: A compreensão da dinâmica intr?nseca em um sistema de controle de rede sem fios (WNCS - Wireless Networked Control System) é relevante para o desenvolvimento e análise de estratégias de controle que proporcionem o funcionamento do sistema em condições adversas, como em casos onde ocorre uma alta taxa de perda de pacotes durante a comunicação. A perda de pacotes é uma das principais deficiências presentes na transmissão de dados sem fios, as quais afetam diretamente a qualidade do sistema de controle. Desse modo um modelo de perda de pacotes preciso é muito importante para o projeto e simulação de WNCS. Neste sentido o presente trabalho analisou o comportamento de um processo, em diferentes níveis de perda de pacotes utilizando o protocolo IEEE (Institute of Electrical and Electronic Engineers) 802.15.4. Foram comparados dois modelos de perda de pacotes, a fim de verificar qual o modelo pode representar melhor esse comportamento em um WNCS. O comportamento real da transmissão foi obtido mediante comunicação entre dois n'os xbees modelo s1. Sobre as perdas reais foram ajustados dois modelos de perdas de pacotes, sendo estes os modelos de Bernoulli, modelo utilizado em softwares de simulação de WNCS/NCS, tal qual TRUETIME e o modelo de Gilbert-Elliot. As análises mostraram em que condições os modelos de perdas diferem na representação do comportamento real do WNCS. Ambos os modelos representaram bem baixas taxas de perdas, mas o modelo de Gilbert-Elliot mostrou ser uma melhor representação para taxas de perdas mais elevadas. Palavras-chave: Sistema de controle em rede, perda de pacote, modelo de Gilbert- Elliot, modelo de Bernoulli.Abstract: The understanding of intrinsic dynamics of a wireless networked control system (WNCS) is relevant to the development and analysis of control strategies to enable the operation of the system under adverse conditions. Packet loss is one of the main deficiencies present in wireless data transmission. An accurate packet loss model is very important to WNCS design and simulation. We analyzed the behavior of a plant under different levels of packet loss using the IEEE 802.15.4 protocol. We compared two models of packet loss in order to check which model can better represent this behavior in a WNCS. The results demonstrate in which conditions the Gilbert-Elliot and Bernoulli models differ in the representation of packet loss for a WNCS. Gilbert model showed to be a better representation specially for higher loss ratios. Key words: WNCS, packet loss, Gilbert-Elliot model, Bernoulli model

Design of Wireless Communication Networks for Cyber-Physical Systems with Application to Smart Grid

Cyber-Physical Systems (CPS) are the next generation of engineered systems in which computing, communication, and control technologies are tightly integrated. On one hand, CPS are generally large with components spatially distributed in physical world that has lots of dynamics; on the other hand, CPS are connected, and must be robust and responsive. Smart electric grid, smart transportation system are examples of emerging CPS that have significant and far-reaching impact on our daily life. In this dissertation, we design wireless communication system for CPS. To make CPS robust and responsive, it is critical to have a communication subsystem that is reliable, adaptive, and scalable. Our design uses a layered structure, which includes physical layer, multiple access layer, network layer, and application layer. Emphases are placed on multiple access and network layer. At multiple access layer, we have designed three approaches, namely compressed multiple access, sample-contention multiple access, and prioritized multiple access, for reliable and selective multiple access. At network layer, we focus on the problem of creating reliable route, with service interruption anticipated. We propose two methods: the first method is a centralized one that creates backup path around zones posing high interruption risk; the other method is a distributed one that utilizes Ant Colony Optimization (ACO) and positive feedback, and is able to update multipath dynamically. Applications are treated as subscribers to the data service provided by the communication system. Their data quality requirements and Quality of Service (QoS) feedback are incorporated into cross-layer optimization in our design. We have evaluated our design through both simulation and testbed. Our design demonstrates desired reliability, scalability and timeliness in data transmission. Performance gain is observed over conventional approaches as such random access