Design of guided shell inclination measurement and display system. based-on MEMS accelerometer

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1 ey Engineeing Mateials Online: ISSN: , Vols , pp doi: / ans ech Publications, Switzeland Design of guided shell inclination measuement and display system based-on MEMS acceleomete Han Jun-li 1,a,Ma xing 1,Yang Xiao-hong 1 1 Special Electo-Mechanic Reseach Institute, BeiJing , China a hjlzlj2008ay@sina.com(coesponding autho) eywods: MEMS acceleation senso;attitude measuement;mc;eo compensation Abstact: Based on the analysis of inclination pinciple sing MEMS acceleation senso,we design the divided voltage cicuit and egulating cicuit.his aticle based on the MC minimum system,using MEMS acceleation senso fo development and application, and the angle infomation can be displayed by LCD o PC.he inclination measuement pecision can each ± 0.2,so it can be used fo measuing the pose of guided shell, aiplane, missiles and othe aeocaft constuction, also can be used in geological exploation and othe fields. Intoduction Angle measuement is vey impotant, no matte in obot [1], the engineeing application [2], and aicaft [3], which equies a benchmak level o the attitude measuement. Measuement data need to be saved o pocessing.at pesent a lot of eseach has focused on how to educe the total dift and impove the accuacy of measuement [4-8].In this aticle, we use acceleation senso and MC to measue the attitude, and then send pocessed data to an extenal device. he design of the attitude measuement system is small in size and has flexible communication mode, high sensitivity. Eo poduced by envionment is compensated with softwae. By compaing test on electical stability chaacteistics of sensos, the attitude measuing display system is moe stable, suitable fo all kinds of envionment measuement equiements. Simulation model Attitude measuing method usually uses geomagnetic sensos o acceleation senso [9].Magnetic sensos ae vulneable to the intefeence of metal components and difficult to measue the object of thee-dimensional attitude alone.acceleation senso can effectively induced changes of gavitational field, and is not affected by electomagnetic field. If using MEMS acceleation senso, not only has good lineaity, small size, but also ease of integation. Figue 1. ilt measuement schematic diagam using acceleomete sensos All ights eseved. No pat of contents of this pape may be epoduced o tansmitted in any fom o by any means without the witten pemission of ans ech Publications, (ID: , Pennsylvania State nivesity, nivesity Pak, SA-05/03/16,21:36:04)

2 ey Engineeing Mateials Vols When the sensos is static, senso s sensitive axial and gavitational acceleation diection angle is the angle of the tilt.as shown in figue 1, the elationship between the acceleation and tilt angle is: A = G n cosθ (1) Whee, A is output of sensitive axis; G n is acceleation value which efeence the gavity; θ is attitude angle.so, the value of θ can be obtained the accosine equation: θ = cos 1 ( A ) (2) G n Analysis pocess 1. System design he attitude measuing system designed in this aticle equies small size, high cost pefomance, can diectly display measuement data o send to the PC. Afte caeful sceening of the device, the designed measuement system is shown in figue 2 below. Attitude measuing module AOP acceleation senso AON Attitude display module LCD display RS232 PC Atmega16 Digital powe Voltage Convete Attitude signal conditioning module Diffeential amplification Filte cicuit Figue 2. Diagam of hadwie 1.1 Attitude measuing module he acceleomete is choosed as attitude measuing senso, which is uniaxial capacitive MEMS acceleation senso and has +5V powe supply. he ange is±5g, 0.5 V to 0.5 V diffeential output on both ends (AOP, AON). 1.2 Attitude signal conditioning module he output end of the is AOP and AON, espectively up to 5V voltage, then passes the diffeential opeational amplifie of AD623. At the same time, in ode to educe the intefeence, using IC cicuit MAX291 as filte, change the voltage signal s amplitude fom 0V to 5V and fequency fom 0Hz to 60Hz, so as to adapt to the Amega16 woking voltage and 8-bit s A/D sampling. 1.3 Attitude display module Choose cost-effective AVR Amega16 as single chip micocompute in the design, which woking voltage fom 4.5 V to 5.5 V. It is the coe of the whole wok, complete a vaiety of data pocessing and exchange. Display is divided into two ways: a diect way is using liquid cystal display(lcd). he pocess of implementation is 1206 display module; Anothe kind of way is using Amega16 s commonly JAG, then though RS232 to PC fo communication.contol commands and measuement data poduced by the PC. his module also includes a digital powe supply, input/output inteface, voltage convesion chip (ams V),etc.

3 1042 Mico-Nano echnology XV 2 Softwae design 2.1 Data lineaization Data lineaization is that voltage collected by Amega16 into acceleation value measued by he acceleomete output is voltage signal, which is needed to calibate the zeo point and scale facto can get the angle calculation. his aticle uses the many position ate tuntable, also is 4 position method, to calibate the senso s zeo point and scale facto. Mainly though the acquisition senso sensitive diection [0,90,180,270 ] s output voltage,which is calculated by the following fomula. = ) / 4 (3) ( D = 90 ) / 2 (4) ( 270 Afte get the senso scale facto and zeo point, the system uses the following model fo calibating: a = ( D ) (5) O / In fomula (3), (4)and(5), is the scale facto of acceleation senso; 0, 90, 180 and 270 ae sensitive diection [0,90,180,270 ] of acquisition senso s output voltage; D is acceleomete s calibated zeo point unde the envionment of tempeatue ; a is the acceleation value afte calibation; O is the output voltage of the acceleation senso. Voltage acquisition in the pocess of system testing calibation can be used with high pecision digital multimete o special collection system.if you use a high pecision digital multimete to collect voltage, need to collect 10 times in the same position, and then calculate the aveage value as the location of the senso output voltage. Afte a calibation calculation, = V/g; D = V. 2.2 tempeatue compensation acceleation senso s zeo point vaies with tempeatue.sually by tempeatue cycle expeiment to calibate the tempeatue deviation coefficient then give tempeatue compensation. his aticle using high pecision data acquisition cicuit to senso s zeo output unde[-40,-30,-20,-10,0,10,20,30,40,50,60,70,85 ]tempeatue envionme -nt, then using MALAB to calculate fitting data as coefficient of tempeatue deviation. Figue 3 is a acceleation senso s tempeatue cycle expeiment (tempeatue-voltage diagam).he X-axis epesents the tempeatue, the unit is.y-axis is the s output voltage value at zeo point, the unit is V.he ed pat is 2 times fitting cuve, the blue cicle epesents aw data of tempeatue cycle expeiment.

4 ey Engineeing Mateials Vols Figue acceleation senso data of tempeatue cycling and fitting hough the fitting calculation, 2 times coefficient 2 = V/ ;1 time coefficient 1 = V/ ;Zeo point D = V. In the pocess of the ealization of the system, is data 1,so = ). empeatue compensation fomula can be expessed as, D = D In fomula (6), D is the zeo point afte tempeatue compensation; (6) D is acceleomete s calibated zeo point unde the envionment of tempeatue ; is tempeatue deviation coefficient; is subtacting value of senso s eal-time using tempeatue and D. 2.3 Acceleation senso s compensation about stability chaacteistics In the use of the acceleation senso, a capacitive acceleation senso of s electical stability time fom 60 s to 90s afte powe on, this is because the device s chaging and dischaging. If you don't compensate fo a peiod of time, this will geatly extend the measuing instument of boot time. So in this aticle, accoding to the steps below to compensate electical stability chaacteistics of the : (1)sing acquisition cicuit to measue acceleation senso s output voltage many times unde the envionment of specific g value input. Sampling time is commonly fom120s to140s (expeience value can be modified). (2)Selecting a single measuement peiod of the chat s (100s~120s ) data to calculate the aveage value as the senso s stability voltage(selection of the time can be modified). (3)Selecting the coesponding measuing cuve of 0s~99s peiod, and using each 12 measuement data points to calculate the aveage as the time value (the length of the sample point can be selected fom diffeent details), time (t1) with 12 points of the last time as a eal time point. (4)Subtact the stable point calculated in (2) to data calculated in (3) to fom an new data. (5) Fit cuve, the new data of (4) as the data fitting and think the distibution of these data ae two distibution and cay on the fitting. (6) Repeat (2), (3), (4), (5), the othe measuement esult data is pocessed. (7) Calculate the same coefficient of each item in (5) as its eal value. (8) o compensate accoding to the following fomula,

5 1044 Mico-Nano echnology XV ' 2 a a = (7) 0 Whee, a is the measuement of oiginal voltage value; 2, 1and 0 espectively is the obtained two coefficients, 1 time coefficient, zeo point; ' a is voltage value afte the compensation. In figue 4 (a)~(b) is the esult of the fou measuements; (e) is calculated aveage value of the many point s fitting figue, black cicles epesent the new data points calculated in steps (3), black cuve epesent fitting cuve in the step (4); (f) is compensation effect figue, cuve of 0~90s is unstable peiod afte compensation, cuve of 90~120s is oiginal measuement data afte senso s output is stability. In the pocess of test, acceleomete is at 0 g condition, the X-axis epesents the time(s); the Y-axis epesents output voltage(v). (a)he fist measuement (b)he second measuement (c)he thid measuement (d)he fouth measuement (e) Data fitting (f)he second measuement compensaton effect Figue 4. Acceleation senso stable chaacteistics and compensation effect

6 ey Engineeing Mateials Vols Expeimental esults hough compensation of the acceleation senso tempeatue and electicity stability chaacteistics, within accuacy measuement with multi position ate tuntable in the scope of 0 ~180.Because of the tuntable s accuacy can each to 0.001, conside it has little angle eo, can be used as an angle of expectations.attitude measuement esults ae shown in table 1. able 1. Result of title angle measuement em Standad angle( ) Inclinomete ( ) em Standad angle( ) Inclinomete ( ) Summay he design of digital attitude measuing system in this aticle is moe flexible and moe widely applied because of two display mode: the adoption of LCD and RS232 communication with the uppe machine.he expeimental esults show that the measuing ange fom 0 ~180, the eo is ±0.2, can meet the equiements of guided shell, unmanned aeial vehicles, ships and othe attitude measuement. Refeences [1]Wei Quan,Hua Wang,Datong Liu.A Multifunctional Joint Angle Senso with Measuement Adaptability[J]. sensos,2013,13: [2]Sha Chengxian,li jie,zhai Chengui,Wang Bo,Hu Lili.Design of digital inclinomete based on MEMS acceleation senso[j].ansduce and Micosystemechnologies,2010,29(6): [3]Su Jun,Wang Zhanping.Design method of Inclinomete based on MEMS acceleomete[j]. Expeimental science & technology,2006,12: [4]Djuić-Jovičić, M.D.; Jovičić, N.S.; Popović, D.B. inematics of gait: New method fo angle estimation based on acceleometes.sensos 2011,11, [5]El-Gohay,M.; McNames, J. Shoulde and elbow joint angle tacking with inetial sensos. IEEE ans. Bio-Med. Eng.2012,59, [6]Ibata,Y.; itamua, S.; Motoi,.; Sagawa,. Measuement of hee-dimensional Postue and ajectoy of Lowe Body duing Standing Long Jumping tilizing Body-Mounted Sensos. In Poceedings of the 35th Annual Intenational Confeence of the IEEE on Engineeing in Medicine and Biology Society (EMBC),Osaka, Japan, 3-7July [7]Shigeu,.; Ryo,.; Hioaki, M. hee dimensional gait analysis using weaable acceleation and gyo sensos based on quatenion calculations.sensos 2013, 13, [8]Lee,G.X.; Low,.S.A Factoized quatenion appoach to detemine the am motions using tiaxial acceleometes with anatomical and senso constaints.ieee ans. Instum.Meas.2012,61, [9]Liu Wufa,Jiang Zhen,Gong Zhenbang.Biaxial tiltmete & application based on MEMS acceleomete [J].Jounal of tansduce technology, 2005,24 (3):86-88.

7 Mico-Nano echnology XV / Design of Guided Shell Inclination Measuement and Display System Based-on MEMS Acceleomete /