Design Of Protocol Stack Of Wireless Sensor Network For Synchronization Acquisition Of Mechanical Vibration

As a new information sensing and data acquisition system, Wireless sensornetwork can avoid the disadvantages of complex wiring, low flexibility, poorexpandability and poor maintainability of wired monitoring system and has greatapplication value in engineering when it is applied to the field of vibration monitoringof machinery and equipment. However, if we want to make wireless sensor networktechnology in the field of mechanical vibration monitoring, in addition to achieve thetwo basic functions of the network self-organization and reliable data transmission, butalso need to address the problems of synchronous acquisition with high precisionbetween multi-nodes. And it should be solved only by designing a protocol stack ofwireless sensor network pertinently. So it is necessary to design a communicationprotocol stack of wireless sensor network for mechanical vibration monitoring.According to the characteristics and requirements of the application of mechanicalvibration monitoring, this thesis summarizes three main functions required by thecommunication protocol of wireless sensor network, including multiple hopsself-organizing, multi-node synchronization acquisition and reliable data transmission,and also designs and realizes a set of communication protocol stack of wireless sensornetwork named STBTC_P based on these need. STBTC_P uses physical layer andMAC layer of IEEE802.15.4as the underlying foundation. Based on this, network layerand application layer are developed and have achieved the realization of all functionalrequirements mentioned above.Before performing synchronous acquisition, in order to prevent different parentnodes assign the same short address to their child nodes in the process of multi-hopself-organizing, STBTC_P adopts distributed address allocation algorithm to coordinatethe address assignment. After successful networking, in order to achieve thesynchronous acquisition of the mechanical vibration, STBTC_P proposes thecentralized associated beacons allocation method to avoid beacon collision, and firstextends the clock synchronization mechanism based on beacon provided by IEEE802.15.4to the whole network to synchronize the clocks of all nodes. Then STBTC_Ptries to achieve commands trigger synchronously using the beacon timing compensationmethod in mufti-hop networks and the two key issues affecting synchronous acquisitionhave been solved. After the completion of acquisition, STBTC_P transmits the vibration data to the center by arranging routing based on the parent-child link, and tries toreduce the packet loss rate by using the subcontracting recovery mechanism at theapplication layer to further improve the reliability of data transmission.In this thesis, STBTC_P is developed using self-designed acquisition nodeWSN-G2.1, and a PC control center is also developed to control and monitor thenetwork. At last, to validate the performance of the developed STBTC_P, multipleexperiments were carried out to test the performance of different functions, includingtiming of transmitting beacon, synchronization accuracy of clock, synchronizationaccuracy of command trigger, throughput and packet loss rate of network. The resultsindicate that most of the features of the STBTC_P are able to meet the requirements ofthe general mechanical vibration monitoring applications, and has a wide application.