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1、 职业技术学院课程设计（论文）基于电子应变式传感器电子称的制作 姓 名： 指导教师： 专业名称： 所在系部： 2011年5月1、 设计任务及要求：设计任务： 利用电阻应变式传感器制作一个电子称，测量范围为2kg,其分辨力为1克，测量 精度0.5RD l字要 求： 1、电阻应变式 2、秤种范围为2kg 3、电路由测量电桥，差动放大电路，A/D转换电路，显示电路组成 指导教师签名： 2011年 3月 20日 二、指导教师评语： 指导教师签名： 2011年5月20 日 三、成绩 2011年6月 10 日 摘 要 电阻应变式传感器具有测量范围广、精度高、误差小和线性特性等优点，且能在恶劣环境下工作，在
2、力、压力和重要测试中有非常广泛的应用，力传感器具有结构简单、体积小、重量轻、使用寿命长等优异的特点。所以电阻应变式力传感器制作的数显电子称具有准确度高易于制作，简单实用、成本低廉、体积小巧、携带方便等特点。 本文从数显电子称的要求分析入手，将整个系统分成四个部分，分析和讨论了各个部分的电路原理、控制策略、实现方法。详细讨论了系统的各种工况及信号的传递情况，并得到了系统各个部分在不同工况的工作状态。数显电子秤根据弹性体（弹性元件，敏感梁）在外力作用下产生弹性变形，使粘贴在他表面的电阻应变片（转换元件）也随同变形，电阻应变片变形后，它的阻值将发生变化（增大或减小），再经相应的测量电路把这一电阻变化
3、转换为电信号(电压或电流），将电信号通过数码显示器显示出来，从而完成了将外力变换为电信号的过程。关键词：灵敏度、电阻应变式传感器引 言电子秤是日常生活中常用的带子衡器，广泛应用于超市。大中型商场。物流配送中心。电子秤在结构和原理上取代了以杠杆平衡为原理的传统机械式称重工具。相比传统的机械式称量工具，电子秤具有称量精度高、装机体积小、应用范围广、易于操作使用等优点，在外形布局、工作原理、结构和材料上都是全新的计量衡器。电子秤的设计首先是通过压力传感器采集到被测物体的重量并将其转换成电压信号。输出电压信号通常很小，需要通过前端信号处理电路进行准确的线性放大。放大后的模拟电压信号A/D转换电路转换成
4、数字量被送到主控电路的单片机中，在经过单片机控制译码显示器，从而显示出被测物理的重量。目前市场上使用的称重工具，或者是结构复杂，或者运行不可靠，且成本高，精度稳定性不好，调正时间长，易易损件多，维修困难，装机容量大，能源消耗大，生产成本高。而且目前市场上电子秤产品的整体水平不高，部分小型企业产品质量差且技术力量薄弱，设备不全，缺乏产品的开发能力，产品质量在低水平徘徊。因此，有针对性地开发一套有实用价值的电子秤系统，从技术上克服上述诸多缺点，改善电子城系统在应用中的不足。目 录摘要.3引言.4目录.5总体规划.61.设计内容及总体方案.6 （1）要求.6 （2）单元电路的具体设计.72.主要原件
5、的说明.7 （1）电阻应变式传感器的组成与原理.7 （2）ICL7107的性能参数.8 （3）LM358的特性及内部构造.83.电路分析与调试.10 （1）总电路图.10 （2）总体框架及原理图.10 （3）各部分电路设计（电阻应变式传感器的测量电路）.11 （4）放大电路.11 （5）A/D转换电路.11 （6）显示电路.11 （7）电路调试.114.系统所需元件列表.135.总结.136.参考文献.14总体规划对于电阻应变式力传感器制作的数显电子称制药有四个方面： 一：电路由测量电桥，二：差动放大电路，三：A/D转换电路,四：显示电路组成。从总的方面来考虑，传感器的使用应该尽量选用稳定性能
6、高，寿命长，结构简单，但是又必须使称重准确。控制电路要根据选用的传感器来设计，主要考虑稳定性，抗干扰性。控制系统应简单实用，并且在称重时能够快速反应，准确计量。总体控制要考虑环境，所称重物体对电路的影响，在确保计量准确的情况下使用能够提高称重效率。总体如图所示设计内容及总体方案要求： 1、电阻应变式 2、秤种范围为2kg 3、电路由测量电桥，差动放大电路，A/D转换电路，显示电路组成 4、工作原理，附系统原理图首先利用由电阻应变式传感器组成的测量电路测出物质的重量信号，以模拟信号的方式传到A/D传感器。其次，由A/D转换电路把由差动放大器把传感器输出的微信号进行一定倍数的放大，然后送A/D信号
7、电路中。再由A/D转换电路把接收到的模拟信号，转换成数字信号，传送到显示电路，最后又显示电路显示数据。电路原理框图电子秤的原理框图：主要原件的说明电阻应变式传感器组成及原理组成：电阻应变式传感器简称电阻应变计。当将电阻应变计用特殊胶剂粘在被测构件的表面时，则敏感元件将构件一起变形，其电阻值也随之变化，而电阻的变化与构件的变形保持一定的线性关系，进而通过相应的二次仪表系统即可测得构件的变形。通过应变计在构建上的不同粘贴方式及电路的不同联接，即可测得重力、变形、扭矩等主要参数。原理：电阻应变式称重传感器是基于这样一个原理：弹性体在外力作用下产生弹性变形，便粘贴在他表面的电阻应变片也随同产生变形，电
8、阻应变片变形后，它的阻值将发生变化，再经相应的测量电路把这一电阻变换转换为电信号，从而完成将外力变换为电信号的过程。ICL7107性能参数双列直插40脚封装，BCB输出积分型模/数转换器，电源电压=5，-5v，电源电流=1.8，-1.8mA,分辨率=3.5digit，典型模拟输入电压=土0.2，,2v，典型模拟输入电流=10pA，时钟频率=48kHz，工作温度=0-70摄氏度。 它的内部包括了线性放大、模拟开关、振荡、显示驱动等部件。该芯片可直接驱动共阳极LED数码显示管（该电路用TOS-5101BR数码管），可显示3位测量电压，电压范围为0-99.9v.可精确到0.1%集成运放LM358特性
9、： 内部频率补偿 直流电压增益高(约100dB） 单位增益频带宽（约1MHz） 电源电压范围宽：单电源（3-30V）； 双电源（土1.5-土15V） 低功耗电流，适合与电池供电 低输入偏流 低输入失调电压和失调电流 供模输入电压范围宽，包括接地 差模输入电压范围宽，等于电源电压范围 输出电压摆幅大（0至Vcc-1.5V) LM358内部包括两个独立的高增益、内部频率补偿的双运算放大器，适合于电源电压范围很宽的单电源使用，也适合于双电源工作模式，在推荐的工作条件下，电源电流与电源电压无关。它的适用范围包括传感器、直流增益模块和其他所有可用单电源供电的使用运算放大器的场合。LM358的封转形式有塑
10、封8引线双列直插式贴片 电路分析与调试1 总电路图电路组装（1）整体设计框架及原理图（2）各部分电路设计1）电阻应变式传感器的测量电路 常用的桥式测量电路如图。 桥式测量电路有四个电阻，电桥的一个对角线接入工作电压E，另一个对角线为输出电压Uo。其特点是：当四个桥臂电阻达到相应的关系时，电桥输出为零，否则就有电压输出，可利用灵敏检流计来测量，所以电桥能够精确地测量微小的电阻变化。2）放大电路 典型的差动放大器如下图所示，只需高精度LM358和几只电阻器，即可构成性能优越的仪表用放大器。广泛应用于工业自动控制、仪器仪表、电气测量等数字采集的系统中3）A/D转换电路4）显示电路电路调试（1）首先在
11、秤体自然下垂已无负载时调整RP1，使显示器准确显示零。（2）再调整Rp2，使秤体承担满量程重量（本电路选满量程为2千克）时显示满量程值。 （调节Rp2衰减比）（3）然后在秤钩下悬挂1千克的标准砝码，观察显示器是否显示1.000，如有偏差，可调整RP3值，使之准确显示1.000。（4）重新进行2、3步骤，使之均满足要求为止。 （5）最后测量RP2、RP3电阻值，并用固定精密电阻予以代替。RP1可引出表外调整。测量前先调整RP1，使显示器回零4.系统所需原件列表待添加的隐藏文字内容2总 结 通过这次课程设计，我们对传感器设计基础知识有了更深入的了解，而且更重要的是又学到了很多新的知识，获得了新的经
12、验。我们从中学会了如何去做设计，深刻了解到团队精神的重要性，在这次的课程设计当中，在一些材料的选用，与其它同学进行了交流，提高了自己的工作效率。 在如此短的时间。依靠个人能力是不可能完成如此繁琐的资料查找与收集的。所以，通过这次课程设计，加强了同学之间的交流，大大增进了我们班的凝聚力，协作的精神更强了。而且自己也学到了很多实际的有用的东西，相信对以后的工作一定会大有益处。 最后，在此对李棚老师的帮助表示深深的谢意参考文献传感器与自动检测Employment tribunals sort out disagreements between employers and employees.You
13、may need to make a claim to an employment tribunal if: you dont agree with the disciplinary action your employer has taken against you your employer dismisses you and you think that you have been dismissed unfairly.For more information about dismissal and unfair dismissal, seeDismissal.You can make
14、a claim to an employment tribunal, even if you haventappealedagainst the disciplinary action your employer has taken against you. However, if you win your case, the tribunal may reduce any compensation awarded to you as a result of your failure to appeal.Remember that in most cases you must make an
15、application to an employment tribunal within three months of the date when the event you are complaining about happened. If your application is received after this time limit, the tribunal will not usually accept i.If you are worried about how the time limits apply to you, take advice from one of th
16、e organisations listed underFurther help.Employment tribunals are less formal than some other courts, but it is still a legal process and you will need to give evidence under an oath or affirmation.Most people find making a claim to an employment tribunal challenging. If you are thinking about makin
17、g a claim to an employment tribunal, you should get help straight away from one of the organisations listed underFurther help.If you are being represented by a solicitor at the tribunal, they may ask you to sign an agreement where you pay their fee out of your compensation if you win the case. This
18、is known as adamages-based agreement. In England and Wales, your solicitor cant charge you more than 35% of your compensation if you win the case.If you are thinking about signing up for a damages-based agreement, you should make sure youre clear about the terms of the agreement. It might be best to
19、 get advice from an experienced adviser, for example, at a Citizens Advice Bureau. To find your nearest CAB, including those that give advice by e-mail, click onnearest CAB.For more information about making a claim to an employment tribunal, seeEmployment tribunals.The (lack of) air up there Watch m
20、Cayman Islands-based Webb, the head of Fifas anti-racism taskforce, is in London for the Football Associations 150th anniversary celebrations and will attend Citys Premier League match at Chelsea on Sunday.I am going to be at the match tomorrow and I have asked to meet Yaya Toure, he told BBC Sport.
21、For me its about how he felt and I would like to speak to him first to find out what his experience was.Uefa hasopened disciplinary proceedings against CSKAfor the racist behaviour of their fans duringCitys 2-1 win.Michel Platini, president of European footballs governing body, has also ordered an i
22、mmediate investigation into the referees actions.CSKA said they were surprised and disappointed by Toures complaint. In a statement the Russian side added: We found no racist insults from fans of CSKA.Age has reached the end of the beginning of a word. May be guilty in his seems to passing a lot of
23、different life became the appearance of the same day; May be back in the past, to oneself the paranoid weird belief disillusionment, these days, my mind has been very messy, in my mind constantly. Always feel oneself should go to do something, or write something. Twenty years of life trajectory deep
24、ly shallow, suddenly feel something, do it.一字开头的年龄已经到了尾声。或许是愧疚于自己似乎把转瞬即逝的很多个不同的日子过成了同一天的样子；或许是追溯过去，对自己那些近乎偏执的怪异信念的醒悟，这些天以来，思绪一直很凌乱，在脑海中不断纠缠。总觉得自己自己似乎应该去做点什么，或者写点什么。二十年的人生轨迹深深浅浅，突然就感觉到有些事情，非做不可了。The end of our life, and can meet many things really do?而穷尽我们的一生，又能遇到多少事情是真正地非做不可？During my childhood, thi
25、nk lucky money and new clothes are necessary for New Year, but as the advance of the age, will be more and more found that those things are optional; Junior high school, thought to have a crush on just means that the real growth, but over the past three years later, his writing of alumni in peace, s
26、uddenly found that isnt really grow up, it seems is not so important; Then in high school, think dont want to give vent to out your inner voice can be in the high school children of the feelings in a period, but was eventually infarction when graduation party in the throat, later again stood on the
27、pitch he has sweat profusely, looked at his thrown a basketball hoops, suddenly found himself has already cant remember his appearance.童年时，觉得压岁钱和新衣服是过年必备，但是随着年龄的推进，会越来越发现，那些东西根本就可有可无；初中时，以为要有一场暗恋才意味着真正的成长，但三年过去后，自己心平气和的写同学录的时候，突然就发现是不是真正的成长了，好像并没有那么重要了；然后到了高中，觉得非要吐露出自己的心声才能为高中生涯里的懵懂情愫划上一个句点，但毕业晚会的时候
28、最终还是被梗塞在了咽喉，后来再次站在他曾经挥汗如雨的球场，看着他投过篮球的球框时，突然间发现自己已经想不起他的容颜。Originally, this world, can produce a chemical reaction to an event, in addition to resolutely, have to do, and time.原来，这个世界上，对某个事件能产生化学反应的，除了非做不可的坚决，还有，时间。A persons time, your ideas are always special to clear. Want, want, line is clear, as
29、if nothing could shake his. Also once seemed to be determined to do something, but more often is he backed out at last. Dislike his cowardice, finally found that there are a lot of love, there are a lot of miss, like shadow really have been doomed. Those who do, just green years oneself give oneself
30、 an arm injection, or is a self-righteous spiritual.一个人的时候，自己的想法总是特别地清晰。想要的，不想要的，界限明确，好像没有什么可以撼动自己。也曾经好像已经下定了决心去做某件事，但更多的时候是最后又打起了退堂鼓。嫌恶过自己的怯懦，最终却发现有很多缘分，有很多错过，好像冥冥之中真的已经注定。那些曾经所谓的非做不可，只是青葱年华里自己给自己注射的一支强心剂，或者说，是自以为是的精神寄托罢了。At the moment, the sky is dark, the air is fresh factor after just rained. Su
31、ddenly thought of blue plaid shirt; Those were broken into various shapes of stationery; From the corner at the beginning of deep friendship; Have declared the end of the encounter that havent start planning. Those years, those days of do, finally, like youth, will end in our life.此刻，天空是阴暗的，空气里有着刚下过
32、雨之后的清新因子。突然想到那件蓝格子衬衫；那些被折成各种各样形状的信纸；那段从街角深巷伊始的友谊；还有那场还没有开始就宣告了终结的邂逅计划那些年那些天的非做不可，终于和青春一样，都将在我们的人生中谢幕。Baumgartner the disappointing news: Mission aborted. r plays an important role in this mission. Starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation
33、or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. It will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising al
34、titude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence.The supersonic descent could happen as early as Sunda.The weatheThe balloon will slowly drift to the edge of space at 120,00
35、0 feet ( Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.Below, the Earth becomes the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, hell be traveling fast, so despite the distance, it will not be like diving i
36、nto the deep end of a pool. It will be like he is diving into the shallow end. Skydiver preps for the big jumpWhen he jumps, he is expected to reach the speed of sound - 690 mph (1,110 kph) - in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he approaches the more
37、dense air closer to Earth. But this will not be enough to stop him completely.If he goes too fast or spins out of control, he has a stabilization parachute that can be deployed to slow him down. His team hopes its not needed. Instead, he plans to deploy his 270-square-foot (25-square-meter) main chu
38、te at an altitude of around 5,000 feet (1,524 meters).In order to deploy this chute successfully, he will have to slow to 172 mph (277 kph). He will have a reserve parachute that will open automatically if he loses consciousness at mach speeds.Even if everything goes as planned, it wont. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is guaranteed to work higher than 25,000 feet (7,620 meters).cause there