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1、研究生课程考核试卷科目： 专业外语 教师： 姓名： 学号： 20140802054 专业：微电子学与固体电子学 类别： 学术 上课时间: 2014年10月至2014年12月考生成绩：卷面成绩平时成绩课程综合成绩阅卷评语：阅卷教师 (签名)The Search of Earthquake Early Warning and Vibration Picking Device Based on MEMSLaibao Yu, Zhigao Chen, Xiongwei Wu, Han Lv(Key Laboratory of Earthquake Geodesy, Institute of Seism
2、ology, CEA, Wuhan 430071)(Wuhan Base of Institute of Crustal Dynamics, CEA, Wuhan 430071)Abstract: A set of earthquake early warning and vibration picking device based on the MEMS technology was designed. The device was tested by using GSK-166 vibration table and compared with standard sensor AC43 t
3、hrough the metrological verification, and theresults showed that the performance parameters of the devicemeet the requirements of earthquake early warning system basically.Key Words: MEMS technology, earthquake early warning, vibration picking device1 Introduction Physics of the earth is a science b
4、ased on observation and measurement, seismology has a rapid development since the instrument have emerged and the method based on the instrument observation was established. After the development of several generations, seismometer have developed from the record by magnifying smoke using initial mec
5、hanical lever to measurement Integrated electronic technology and computer technology, improved the frequency band range and detecting precision substantially, and it make the seismological research and development enter a new stage. With the research and development to seismology science and requir
6、ement of space detection to the moon and the mars, combining with development of the modern electronic and computer technology, modern seismic sensors need to develop towards low power consumption, miniaturization, chip, low cost and high reliability, and be able to get full band observation and mea
7、surement. Modern measurement instrument based on mechanical hammer have some advantages such as high low resolution, large dynamic range, but show the deficiencies in the application. Micro Electronic Mechanical System is based on the integrated circuit technology and micro mechanical process, and t
8、hen integrate the mechanical components, optical system, driver components, electronic control system as a whole unit, has small volume, light weight, small consumption, low cost, easy to integrate and strong overload capacity. Now there is a micro mechanic seismic accelerometer instrument based on
9、MEMS technology, which is smaller than a coin in volume, power consumption only in milliwatt level, and can be applied to earthquake observation and measurement. Earthquake early warning tested the earthquake parameters quickly using the earthquake instrument, and released the information of the ear
10、thquake such as time or degree before the arrival of the destructive earthquake waves. It is very important to get earthquake signal for earthquake early warning, the frequency of natural earthquake signal rank from 0100HZ,the demand to the low frequency is very high, and the signal is too weak to m
11、easure easily, so it is hard to get accurately. Traditional earthquake signal acquisition system can not meet the demand because of the large volume, narrow frequency band, high energy consumption and small dynamic range, but the earthquake signal collecting system for acceleration sensor based on M
12、EMS technology can meet the requirement above. Aiming to the instrument index applied to earthquake, in this paper a new kind of MEMS micro accelerometer instrument was designed, which has large dynamic range, good linearity and low mechanical noise. Sensor can bear the impact of the acceleration si
13、gnal about 1000g.2 Methodology and Experiments2.1 Selection of ChipAt present, our country has no clear standards in the index of the earthquake early warning system. The thesis combines with the standard of the strong earthquake instrument: digital earthquake accelerometer, and surveys the earthqua
14、ke early accelerometer in the word now. By analyzing the technical parameters of existing earthquake early warning system, Sums up the important index of the earthquake early warning system, as shown in table 1.Index countries and regions America Japan Taiwan TurkeyType 3 axis 3 axis 3 axis 3 axisMe
15、asure range 4g 4g 2g 2g Frequency range DC200HZ DC100HZ DC50HZ DC50HSensitivity 2.5V/g 2.5V/gDynamic range 155dB 96dB 108dBTransverse sensitivity 0.03g/g 0.03g/g 3dBTab.1 Parameters of seismic monitoring device2.2 Hardware DesignDevice select C8051F020 as main control chip, adopt 16 bites double cha
16、nnel A/D chip LTC1865 as collection chip, as shown in figure 1. The device is only in designing phase. The data detected is sent to PC by UART, and network structure and related hardware will be designed in further work.Fig.1 Structure chart of hardwareHAAM-326B1 integrates signal low-pass filter ci
17、rcuit, and low-pass filter can be realized only by providing external capacitance. The filtering capacitor can be get by calculating:F-3dB=12Rout32KCx,y,z Considering the frequency range of natural earthquake, set 50HZ as cut-off frequency, and low-pass filter capacitor is 0.1Uf by calculating. In o
18、rder to improve the precision of A/D, the external high precision voltage source MAX873 is used for the device. Theearthquakesignalisweakandinterferenced easily, so taking measures to reduce the system interference is very important. There are many interference factors, including signal channel inte
19、rference and power interference and so on. Signal channel interference comes from the common-mode interference resulted in internal resistance which pass through all kinds of signals in the system, the total interference among the amplifying circuits, electrostatic coupling interference caused by th
20、e high frequency signal in the circuit. The power interference is the interference generated by the voltage noise caused by the unstable power voltage coupled to the system. Interference methods mainly include:1) GroundingGrounding is the primary method to stop the interference. Accurate and reliabl
21、e grounding can eliminate the nosy voltage caused by passing all the circuits. The frequency of analog signal of the system is below 1 kHz. It is low frequency circuit, whose inductance not the main problem between components, but when the grounding forms a loop, it will cause a great effect on the
22、circuit, so we take the way of one point grounding. In addition, power lines and signal lines should be separated. Besides, when making the design of analog circuit, in order to remove the coupling in the analog circuit and noise reduction, we should make the free input of the analog signal connect
23、ground by high level.2) filter wave There are two kinds of filter named power filter and signal filter respectively. The device adopts a simple power filter wave circuit and filter with EMI chip. The noise of the circuit reduces obviously after filter. Signal filtering is mainly to reduce the use of
24、 capacitance and inductance, using the resistance to reduce the mean square value of the thermal noise.2.3 Software Design Modular design is used in the device software including module block, gathering module and communication module and so on, the software process as shown in figure 2. Fig.2 Flow
25、chart of softwareConsidering the data requirement of the software filter and earthquake instrument system, the sampling frequency of LTC1865 is set 20Ksps, and the serial baud rate is set 38400.2.4 Test Vibration table GSK-166 is the production of Swiss Geosig Company. The frequency of the GDK-166 r
26、ank from 050Hz, maximum speed is 4.8 m/s, maximum acceleration is 5g, effective range is 660nm, and all kinds of seismic waveform can be simulated.3 ConclusionThe thesis combines with the standard of the strong earthquake instrument: digital earthquake accelerometer. Through analyzing the technology
27、 parameter of the earthquake early warning system in the word, this paper summarizes the basic parameter demand of the earthquake early warning system. The device selects C8051F020 as main control chip, adopts 16 bites double channel A/D chip LTC1865 as collection chip, and selects MEMS chip HAAM-32
28、6B1 as acceleration test chip. Modular design is used in the device software including module block, gathering module and communication module and so on. The device is tested by using GSK-166 vibration table and compared with standard sensor AC43 through the metrological verification. Considering th
29、e data requirement of the software filter and earthquake instrument system, the sampling frequency of LTC1865 is set 20Ksps, and the serial baud rate is set 38400. The data is filtered before being sent, and every data is two bites. When the design of the device is completed, it will be working all
30、the time. It is proved that the response of the device to all kind of vibration is rapid, and the operation is stable too. Results show that the basic parameters of earthquake early warning system of the device designed can meet the requirements of the system. Compared with traditional mechanical st
31、ructure, the device based MEMS technology is smaller in size, the biggest is no more than one centimeter, even just for a few microns, and its thickness is smaller. Using in integrated circuit, the cost will be lower, the power consumption can be reduced.4 Acknowledgements The authors wish to thank
32、Key Laboratory of Earthquake Geodesy, Institute of Seismology and Wuhan Base of Institute of Crustal Dynamics which provide a comfortable place and financial support. The authors would like to thank all the colleagues for valuable suggestions. The authors would like to thank father and mother. If th
33、ere is no their encouragement and support, the paper would not be competed. 5 References【1】 Qiufang Ma. The development of natural seismic signal acquisition system based on MEMS technology D. China University of Petroleum, 2007.【2】 Shirong Lin. The research of seismic instrument index system and the design of MEMS instrument D. Key Laboratory of Earthquake Geodesy, Institute of Seismology, 2012.【3】 Daozhong Li. The design of the strong vibration lack box based on MEMS accelerometer J. Geodesy and geodynamics, 2010, (S2): 126-128.