Research On Principle And Implementation Of WSN For Virtual Instrument Infrastructure

As a new means for information access, Wireless Sensor Networks (WSN) can be deployed quickly, and can be applied widely. A typical application of WSN is that the sensor nodes monitor surrounding environment and report to supervisor what happened and the target state in many to one communication. Virtual Instrument(VI), a monitor and control system, which is composed of computer, Modular instrument hardware and software used for data analysis, inter-process communication and graphical user interface, indicates the highest level of intelligent instrument. VI is integrating various kinds of new technology to improve its intelligence and ability, and to deal with the challenges of development.By other’s faults, wise men correct their own. Original invention or breakthrough in science and technology often appear on the bases of crossdisciplinenary. With the function of data acquisition and data transmission which are necessary to VI, WSN can serve as its body to sample, transmit and process the information and acts as its digital remote receptor. Combining WSN and VI and constructing new VI with the advantage of WSN, which have combined the latest progress of computer, communication, instrumentation and some related disciplines, that is the general trend of historical development.Orienting the application of WSN, the dissertation regards the WSN as an infrastructure for VI and focus on the technology issues when WSN is applied to VI. The main research and contributions are as follows:1. In order to match VI, the issues about the architecture ofⅥbased on WSN, the issues about the application layer protocol for WSN, the issues about the topology control of WSN, the issues about synchronous sampling of target state and real-time transmission (MAC protocol), the issues about the adaptability of WSN and the issues about the distributed coordination of VI (data integration) are introduced.2. Aiming at the issues about architecture ofⅥand the issues about application layer protocol for WSN, the dissertation designs the architecture ofⅥ, the node hardware framework of WSN and its protocol stack; it describes the working process ofⅥbased on WSN and provides the working state of WSN nodes and the inter-state conversion method; basing on cross-layer design idea, it devises the application layer protocol for WSN; at the same time it projects the format of general frame, data frame, command frame on the application layer, defines the order on application layer and offers the command format and function description.3. Topology control of WSN is the basis to meet the needs of VI in the aspect of sampling and transmission. To solve the topology control problems, the dissertation designs topology detection method and process which is based on application layer protocol VI-APL for WSN; it designs the expression method of topology information and puts forward the election principle for link weight; it puts forward tree cluster topology control algorithm—VITDT, offers the process to implement the algorithm and the VITDT-based method to control the power, and proves the effectiveness of the algorithm by simulation.4. To meet the needs of VI to sample the target synchronously, combining with WSN topology control, the dissertation puts forward a new synchronization mechanism for WSN—Broadcast Tree Delay Synchronization Mechanism (BTDTS), introduces the principle of BTDTS and gives the performance analysis; to solve the problems of WSN for real-time data transmission, it puts forward a MAC protocol which is based on global synchronization and TDMA—TSMAC (Tree Slot MAC). TSMAC protocol ensures the transfer time in WSN is predictable and access is fair among the nodes.5. Data fusion involves the WSN adaptability and distributed coordination of VI. The dissertation analyzes the movement of the sample data of WSN over time, defines a concept of time-sensitivity and puts forward a sensor classification method by time-sensitivity; it puts forward a data fusion method based on time-sensitive, gives process of data processing, offers the theoretical analysis and the actual test of the algorithm, and the effectiveness of this method is verified.6. A VI is designed based on MSP430 WSN node that is originated by ourself, which takes advantage of techniques and algorithms that are involved in this dissertation. As an instance, Putting this VI into Mobile Computer Room Environmental Control, it shows that WSN based VI have great advancement in the aspect of convenience and effectiveness.Focusing on how to apply WSN into the filed of VI, the dissertation analyses and solves the problems when the application occurs. The research is instructive to the application of WSN and especially to centralized WSN.