Study On The WSN Based On MEMS Sensors

Wireless sensor network, integrating with sensor technology, embedded computing technology,distributed information processing technology and wireless communication technology, has becamea new research field and had very broad application prospect. The technology originated in themilitary project, with the characteristics of high density of nodes, strong network dynamic,organization network, diversification in data access method and the others. With the development oftechnology now it is widely used in military, medical, monitoring, intelligent traffic etc. MEMStechnology is a new and rapidly developing technology. It has the vast development potential andmarket prospects. This paper researched wireless sensor network based on MEMS sensor. Theimproved new type of high precision MEMS capacitive accelerometer sensor was used in thewireless sensor network. The software and hardware were studied and designed. Thecommunication between nodes was realized through the experimental.Firstly, the paper studied the wireless sensor network and its node and described the concept ofWSN. The characteristics and some crucial problems of the WSN are summed up. The basic frameof the node in the WSN was proposed. The node was divided into four modules according to theirfunctions: the sensor module, the processor module, the wireless communication module and thepower management module. Node modular was helpful to analyze and research. And then theconstraints of WSN and its node were analyzed.Then the paper introduced MEMS sensor, described the working principle of the accelerometerwith the actuators droved by Lorenz force for increasing the initial sensing capacitance. Thestructure of the sensor was improved to be aimed at the deficiency of the original design, andproposed the capacitance detection circuit. Through the ANSYS software, the sport mode, the staticsensitivity and impact resistance of the sensor designed are simulated and analyzed. Results showthat the stiffness of support beam is large in non-sensitive direction, and lower sensitivity of theacceleration signal, which greatly inhibits the axial cross-effect. The sensitivity of the sensor in thesensitive direction Y axis is 0.558μm/g, and the accelerometer can sustain 1000g acceleration.On the basis of the analysis above, the hardware and software systems were designed in thepaper. The low power MSP430F1611 chip and the CC2430 chip supporting for ZigBee were used inthe hardware system. The processor module, wireless transceiver module and power supply modulewere designed from the angle of each function module, which included the serial storage circuit ofthe processor module, clock circuit, UART circuit, JTAG interface circuit, interface circuit of thewireless transceiver module and interface configuration between the MSP430F1611. In software system, the paper mainly designed and realized the serial communication, FLASHdrive, real-time clock, the data acquisition and wireless data communication. In order to improvethe real-time response and meet the task demands, firstlyμC / OS - II operating system wastransplanted into the MSP430F1611 processor of the gateway node, and the codes were introducedwhich were needed while transplanting theμC / OS–II. And then the functions of serialcommunication, FLASH drive and timing clock were realized. In the wireless transceiver module,the node data acquisition and processing and wireless data transceiver were mainly designed.Through ZigBee agreement data collecting by node was sent to the gateway node and then uploadedto the PC machine.Finally, the system was debugged and the node physical map was given. The paper introducedthe problems encountered when debugging the hardware and software systems and gave theexperiment results of nodes communication.