Research On Distributed Measurement And Control System Modeling And Its Real-time Performance

With the modernization of science and technology and the formalization of industry and agriculture production, the technology of computer and communication has obtained the high speed development and widespread application, which has resulted in the distributed measurement and control system based on the technology of network communication and modern measurement and control. The distributed measurement and control system has realized the present, remote and network of measurement and control, which becomes the focus spot. However, the existing theory fundamental of distributed measurement and control system is still not mature, its' solution has some limitation and the technical performance also needs being further enhanced. Taking the Sichuan education department, the Chengdu Science and technology Bureau key scientific research item "the research on measurement and control system modeling and confirmation technology based on network measurement system performance evaluation" and "the research on measurement and control system modeling and performance survey based on the network environment" as background, this dissertation studies the theory and practices exploration of system modeling, architecture and real-time of distributed measurement and control system.This dissertation proposes the abstract mathematical model of EFPS, and applies it in the modeling of distributional measurement and control system. Based on comparison with two kinds of typical object modeling technology, this dissertation gives the definition of EFPS model and discusses each element of EFPS model, analyses the virtues and the solved problems of EFPS model. Launching the discussion on the key factors of EFPS model, which is the hardware entity, the software entity and the abstract entity, this dissertation pointes out the transformed relations between entities, and proposes the application for the four essential elements confirmation principle of EFPS model. At the same time, the dissertation has established the description model of distributed measurement and control system by the aid of the EFPS model, which regards the distributed measurement and control system as an organic whole that is made of each part of constitution, carries on the formalization description from the system structure and the mechanism, and becomes the research basis of distributed measurement and control system architecture, the real-time performance.This dissertation discusses the architecture of distributed measurement and control system. The architecture of distributed measurement and control system relies on the architecture of computer network; however, the existing architecture of computer network that applies in measurement and control system expose a lot of flaws. Combining with the resent research of network architecture, this dissertation first employs non-level Service Unit Network Architecture to build the distributed measurement and control system, and studies the realization of distributed measurement and control system based on the Service Unit based Network Architecture. For the real-time performance, the virtual circuit between ports is firstly used to build the distributed measurement and control system. The virtual circuit between ports can distinctively processes data streams from different ports between network measurement and control nodes, can preferably resolves several key indicators such as real-time, confirmation, robustness of distributed measurement and control system.This dissertation studies the real-time of distributed measurement and control system. Firstly, this dissertation introduces the basic concepts about real-time system and quality of service, discusses the real-time features and models of distributed measurement and control system, gives the definition of RQoS and the index systems, establishes the abstract real-time service functions and discusses the applications of real-time quality of service. Secondly, by using the modeling simulation tool of OPNET, this dissertation analyses the network model, node model and per node's process model of Service Unit based Network Architecture, compares the node model based on the Service Unit based Network Architecture the modeling of OPNET builds the foundation for further studying the real-time performance of distributed measurement and control system based on the Service Unit based Network Architecture. Thirdly, by using the modeling simulation tool of OPNET, this dissertation carries on the real-time simulation experiment and analysis based on traditional Ethernet of sharing type, Ethernet of exchange type and the distributed measurement and control system with router. Taking this as the foundation, this dissertation carries on simulation experiment based on the distributed measurement and control system of Service Unit based Network Architecture and comparative analysis, which confirms the accuracy and feasibility of this schema, and can enhance the real-time performance of distributed measurement and control system.