Design of Teaching Platform Based on Information Detection System

Transcription

1 , pp Desgn of Teachng Platform Based on Informaton Detecton System Zhenjng Yao, Lxn L, Qn Gao & Zhmng Han Insttute of Dsaster Preventon Sanhe, Hebe, People s Republc of Chna zjyang4@sna.com Abstract. The engneerng practce teachng of sensor and detecton technology based experments wth an envronmental dstance nformaton detecton system s proposed n ths paper. The experments have been conducted ncludng ntroducton prncple of sensor, choose sensor, desgn of electronc crcut, sgnal transmttng module. The engneerng-orented method can contrbute greatly to arousng student s nterest and developng ther nnovatve abltes. The results of students learnng show that ther problem-solvng and engneerng applcaton ablty had mproved. The engneerng practce teachng s benefcal to the development of applcaton-orented unversty educaton. 1 Introducton The Insttute of Dsaster Preventon s an applcaton-orented nsttute. Its orentaton s to cultvate appled talents to satsfy needs of the socety. These undergraduate needs to have deep theoretcal bass and broad professonal knowledge, as well as has engneerng practce ablty and comprehensve creatve capacty [1][2]. Therefore, undergraduate engneerng practce teachng level s an mportant measure of an applcaton-orented unversty s teachng level. Sensor and detecton technology plays an mportant role n ndustral producton and scentfc research. Partcularly n recent years, ndustral producton ncreasngly depends on sensor and detecton technology wth the rapd development of mcroelectroncs and ndustral automaton. Sensor and detecton technology, whch s the fronter scence and technology, s one of mportant base course for the specalty of measurement technology and nstrument [3][4]. Ths course teachng has mportant meanng for brngng up students ablty of lnkng up theory wth practce and engneerng applcaton capacty of measurement and control system. It has become ncreasngly mportant for students future work. Many companes hre staff wth practcal applcaton of sensor before graduaton. Hence, the sensor applcaton level s an mportant measure of an applcaton-orented unversty students professonal skll level. Sensor and detecton technology s a practcal techncal course whch can mprove students engneerng applcaton ablty and nnovaton capacty. Ths course nvolves physcs, electroncs, mechancal, optcal, acoustc, and many other dscplnes, whch has relatvely ndependent content and lacks of systematzaton and contnuty. So ISSN: ASTL Copyrght 216 SERSC

2 students feel the course s dffcult to understand and memorze [5] In the tradtonal classroom teachng of sensor and detecton technology at present, there are some problems of takng theory serously and makng lght of practce. Students feel t hard to get an effcent result or borng to study, and lack ntatve and enthusasm to ths course. In the tradtonal teachng mode, the students have learned how detect nonelectrc sgnal wth sensor, but had not learned how to apply sensor for detectng nonelectrc sgnal [6][7]. The tradtonal teachng mode s not n favor of tranng students engneerng applcaton and creatvty ablty [8]. For applcaton undergraduate course college, the goal of sensor and detecton technology teachng s not to desgn sensor, but to apply sensor for detectng non-electrc sgnal [9]. In order to tran students ablty n engneerng practcal and creatvty, the engneerng practce teachng s presented n ths paper. It teaches students how to construct a complete detecton system usng a sensor. Ths engneerng practce teachng content ncludes choose sensor, desgn of electronc crcut, sgnal transmttng module, etc. In ths paper, an envronmental dstance nformaton detecton system usng ultrasonc sensor s desgned. It can make students not only understand sensor theory deeply, but also learn to apply sensor for solvng engneerng problems. The engneerng practce teachng trans students n engneerng applcaton ablty and mproves the students nnovatve capacty. 2 The Proposed Engneerng Practce Teachng The content of sensor and detecton technology course ncludes ntroducton prncple of sensor, choose sensor, desgn of electronc crcut, desgn of detecton system usng sensor, sgnal transmttng module, etc. The engneerng practce teachng project n ths paper would desgn an envronmental dstance nformaton detecton system usng ultrasonc sensor. 2.1 Introducton Prncple of Ultrasonc Sensor Ultrasonc sensor s a converson component, whch transforms the ultrasonc sgnal nto electrcal sgnal or electrcal sgnal nto ultrasonc sgnal. The ultrasonc sensor, whch has large sze, wde frequency band and hgh operatng voltage, had been wdely used n dstance nformaton detecton system [1]. The dagram of electrostatc ultrasonc sensor was shown n Fgure 1. Electrostatc ultrasonc sensor was composed of back electrode and metal flm. In order to make the ultrasonc sensor work n a lnear state, a bas voltage must be added between back electrode and metal flm. When an alternatng voltage was added between back electrode and metal flm, ultrasonc wave was transmtted by metal flm forced vbraton. For another, when ultrasonc wave acts on metal flm, forced vbraton of metal flm was occurred. Then dstance between metal flm and back electrode was changed. Hence, the capactance of the metal flm and the back electrode was changed correspondngly. In the end, the voltage between metal flm and back electrode was changed. Therefore, ultrasonc sensor s a converson component between ultrasonc wave and voltage sgnal. 44 Copyrght 216 SERSC

3 back electrode alternatng voltage C Ut R metal flm U bas voltage Fg. 1. The dagram of electrostatc ultrasonc sensor. 2.2 Desgn of Envronmental Dstance Informaton Detecton System Fgure 2 shows the hardware mplementaton of envronmental dstance nformaton detecton system. The system ncludes ultrasonc transmttng crcut and echo sgnal recevng crcut. In ultrasonc transmttng crcut, coded modulaton exctaton sequence was sent from the feld programmng gate array (FPGA). After power amplfyng, the ultrasonc sensor was trggered to transmt ultrasound. In echo sgnal recevng crcut, after band-pass flterng, shapng and the polarty correlaton between the bnary echo sequence and a reference echo sequence was carred out. The reference echo sequence was recoded from an acrylc board placed 4 cm n front of the ultrasonc sensor. Lastly, the dstance calculaton was mplemented f the echo sequence was recognzed to be from ts own sensor transmsson. Coded modulaton exctaton sequence Ultrasonc transmttng crcut Power Amplfer Ultrasonc Sensor Ultrasound Echo Obstacle Dstance Calculaton Polarty Correlator Shapng Crcut Band-pass Flter Echo sgnal recevng crcut Fg. 2. Hardware mplementaton of envronmental dstance nformaton detecton system. 2.3 Desgn of Ultrasonc Sensor s Drvng Crcut Ultrasonc drvng crcut s a key part of the ultrasonc transmttng crcut. Fgure 3 shows the transformer based ultrasonc drvng crcut. After transmttng coded modu- Copyrght 216 SERSC 45

4 laton exctaton pulse sequence, the Mosfet Q1 was workng n swtchng of power semconductor. So varyng electrc current, whch produced by the prmary col of transformer T1, can generate magnetc flux. It produced nductve voltage n the secondary col of transformer T1. The nductve voltage n secondary col was n tmes hgher than that of prmary col. Where n s the col rato between prmary and secondary cols. Lastly, the hgh voltage can excte ultrasonc sensor to transmt ultrasound. VCC T1 C1 D4 pulse sequence Q1 2 D2 D1 D3 Fg. 3. Ultrasonc drvng crcut. 2.4 Desgn of Sgnal Transmttng Module In order to obtan both hgh resoluton and long operatng range of envronmental dstance nformaton detecton system, the coded exctaton sgnal and pulse compresson technque were used n ultrasonc dstance measurement. In the sgnal transmttng module, the coded modulaton exctaton sequence was constructed. In ths paper, the chaos pulse wdth modulaton (CPWM) exctaton sequence was emsson n the envronmental dstance nformaton detecton system. In the CPWM exctaton sequence, the wdth of carrer pulse was modulated by chaos code. The perod of carrer pulse remaned the same. The pulse wdth CPWM exctaton sequence was expressed as follows, tcpwm tc y, 1,2, n 1 2 t of CPWM In the CPWM exctaton sequence, y (=1,2,,n) was chaos codes, n was pulse number, t c was perod of carrer pulse, (,t c) was range of pulse wdth. (1) 46 Copyrght 216 SERSC

5 2.5 Envronment Dstance Informaton Detecton Experment The dstance measurement experments of envronmental dstance nformaton detecton system were mplemented n sensor and detectng technology laboratory. The ultrasound propagaton speed n ar can be calculated as follows, v = v T T. (2) Where v = m s and T = K. In our experments, the ultrasound speed was about m/s at 27 C temperature. The dstance between ultrasonc sensor and obstacle can be calculated as follows, v t d = TOF (3) 2 Where t TOF s the tme of flght. 4 Conclusons The engneerng practce teachng method was proposed for teachng sensor and measurement technology at Insttute of Dsaster Preventon. An envronmental dstance nformaton detecton system was desgned, whch ncluded ntroducton prncple of sensor, choose sensor, desgn of electronc crcut, desgn of detecton system usng sensor, sgnal transmttng module, etc. The proposed teachng method can combne theory wth practce of sensor and measurement technology course. Students can master the workng prncple of sensor and how to apply sensor for detectng nonelectrc sgnal. The proposed teachng method concentrates on student-ablty-orented usng engneerng practce. Its purpose s to enhance students practcal engneerng applcaton capacty and nnovatve ablty, whch s especally mportant n the applcatonorented unversty. Hence, students n engneerng practce teachng classroom can develop students professonal skll level. Ths provdes foundaton for students n ther future work. Copyrght 216 SERSC 47

6 Acknowledgements. The work was supported by the Scentfc Technology Research Projects for Hgher Schools n Hebe Provnce (No. ZD21424), Specal Fund of Fundamental Scentfc Research Busness Expense for Hgher School of Central Government (No. ZD21424), the Fne Constructon Course projects funded by the Insttute of Dsaster Preventon (No. JPJS2161), and the Specal Fund of Fundamental Scentfc Research Busness Expense for Hgher Schools of Central Government (Projects for creaton teams) (No. ZY21614). References 1. Lu, Y., Yang C., and Zhou Q.: Research on sustanable practce teachng system of the applcaton-orented specalty. Internatonal Conference on Scalable Computng and Communcatons - the 8th Internatonal Conference on Embedded Computng, ScalCom- EmbeddedCom, (29) L, F., Hu, R., and Fan X.: Innovaton of engneerng educaton models n applcatonorented nsttutes. Internatonal Conference on Educatonal and Informaton Technology (ICEIT), (21) v Lu, S.: Study on the constructon pattern teachng of sensor and detectng technology. Chna Electrc Power Educ., 3, 14, (214) Wang, W., and Guan, F.: Teachng reform and exploraton of the course Sensor Technology. World Trans. on Engng. and Technol. Educ., 11, 3, (213) L, C., Hou, R., Fan, S., Guo, Z., and Xng, W.: Desgnng experment teachng for sensor course. Research and Exploraton n Laboratory, 29, 1, (21) Xu, K., and Yang, S.: Performng sensor dynamc response experments n classroom. Research and Exploraton n Laboratory, 28, 9, (29) 36-38, Wu, L., Ln, A., and Lu, C.: Research on teachng of the course of prncples and applcatons of sensor. Hgher Educaton Forum, 4, (28) Zhu, L., L, Y., Qan, M. and Xa, H.: Teachng reformaton of sensor and detectng technology. J. of East Chna Insttute of Technol., 3, 1, (211) Lu, Q.: Experments and engneerng practce n the classroom teachng of sensor and detecton technology. World Trans. on Engng. and Technol. Educ., 13, 1, (215) Wu, J.: Prncple and applcaton of sensor. Bejng: Chna Machne Press, (213) Copyrght 216 SERSC