电子水平仪英文文献.doc

学士学位论文英文翻译部分题 目： 电子水平仪设计院 （系） 专 业 学 生 学 号 班 号 指导教师 翻译提交日期 哈尔滨工业大学教务处制Study on a New High Accuracy Dual-axis Electronic LevelAbstractThe study and the development of a new dual-axis, high accuracy and low cost elec-tronic level have been introduced. In this paper, the idea of the overall design is described, and the de-termination for the main mechanical and electronic parameters, including the overall testing, has beendiscussed in detail. Based upon the practical characteristic and the specifications of the instrument, it willbe widely used in the field of machine tool, automobile, airplane and shipping manufactures.Key Words: Electronic level; Plate spring; LVDT; Tilt measurement1 IntroductionThe new dual- axis electronic level is called tilt sensor too. It is a unique tilt measuring system capable of simultaneously recording the degree and direction of tilt with high accuracy up to 1 arc-sec. within a range of 400 arc-sec., up to 3 arc-sec. within a range of 800 arc-sec. It has a reading resolution up to 0.1 arc-sec.The working principle of the instrument is shown in Fig.1. It is composed of three parts. One part is the combination of the support frame and the base. Another part is stationary work-piece 5 fixed on the top of sup-port frame. The third part is the swing work-piece 2. The work-pieces 5 and 2 are connected by a pair of double plate springs 3.During measurement if the surface which the instrument is set on is tilt, the whole structure of the instrument will tilt too. But the swing work-piece 2 will move back along the reverse direction to the tilt by the gravity. Therefore, the coil and the core of the LVDT (linear variable differential transformer) will have relative displacement, and the relative displacement will be converted to analog voltage output. The pair of plate springs are guide way to keep the swing work-piece 2 moving. Fig.1 The structure of the electronic level.Because of the simple structure of the instrument, it is working without wear and tear, also no cross influence upon the function or precision. It is suitable for wide field of application in quality assurance and engineering, two examples are given as follows. compensate the tilt of a measured equipment can be reached. The purpose of using another head of the instrument is the same as in above example.1.1 Checking the flatness of measuring tablesThe application process is shown in Fig.2(a). One head of the instrument is set on a standard triangular base. During measurement, the triangular base is moved against a ruler step by step. Every step is just equal to a side length of the triangle. Two dimensional tilt data are picked up in every step by a computer. The another head of the instrument is set on a corner of the measured table to monitor the deformation of the whole table. Usually the micro-deformation of the whole table is caused by the weight of the testing instrument with continuous moving.Fig.2 Application Examples.1.2 Monitoring the level or compensating the tilt of a measuring equipment automaticallyThis application process is shown in Fig.2(b). One head of the instrument is set onthe slide stage of a measured instrument or a machine tool. Another head of the instrument is set on the base of the measured equipment. During the slide stage moving, two dimensional errors of the guide way, pitch and roll errors, are picked up automatically by a computer. Therefore, to monitor the level or to compensate the tilt of a measured equipment can be reached. The purpose of using another head of the instrument is the same as in above example.2 The principle of operationDuring measurement, the instrument is set up on a surface to be measured and is adjusted to the zero indication with three screws 8. If the surface is tilted a small angle 角度to the horizontal, then the swing part will bear a force F and a force couple M. With the multiple influence of F and M , a deflection Y of the double plate springs will be generated as shown in Fig.3. It can be expressed by the formula (1): Fig.3 The working situation of the plate springs. Here: E is the elastic modulus of the spring ,I is the moment of inertia. Also (b is the width，h is the thickness of the springs) is known. Because the tilt angle H isonly within 800 arc-sec.,F=Psincan be written as F=P. Therefore, the formula(1) becomes to Upon the formula (2), obviously the deflection of the springs is linear with the tilt angle .Suppose the absolute zero of the instrument is just indicating the globe level, then the center of the core will coincide with the center of the coil of a LVDT. When a tilt of the surface take place, the two centers of the core and the coil will move relatively following the swing part. The larger of the tilt will lead to the longer of the distance of the two centers. The mechanical displacement will be converted to a bipolar dc voltage by LVDT and its subsystem AD598 chip.3 Design of the main systemDuring design, the important factor is to control and decrease the hysteresis of thespring. In order to reach this requirement, two principles should be obeyed: First, the material of the spring should possess smaller hysteresis, so we have chosen a kind of spring made of Ni-Ti-Al series alloy that is better for this requirement. Second, during work, the maximum deflection Y should be smaller than the maximum elastic displacement of the spring about 45 times. The maximum elastic displacement of the spring max is :Here is the elastic limit of the spring. Also, considering the whole size of the instrument, we set the length L of the spring to be 60mm, width b =25mm, and thickness h=0.15mm. According to the formulae (2) and (3), we set the maximum deflection of he spring Y to be 0.2mm, within the maximum working range =800 arc-sec.Based on the requirements of the range and 0.1 arc-sec. resolution, we can get the requirements for choosing LVDT. Miniature type of LVDT, MHR series (010MHR), is chosen. Its specifications are listed in Table 1.Table 1The circuit for conjunction with LVDT to convert transducer mechanical position to abipolar voltage with a high degree of accuracy and repeatability is shown in Fig. 4. We choose an integrated circuit chip AD598. The AD598 contains a low distortion sine wave oscillator to drive the LVDT primary. The LVDT secondary output consists of two sine waves that drive the AD598 directly. The AD598 operates upon the two signals, dividing their difference by their sum, producing a scaled bipolar dc output. For a full-scale displacement of Y=0.2mm, the voltage output of the AD598 is computed by formula (4):Where S=126mV/(V#mm) is LVDT sensitivity ,Vout =4V is the full range output voltage ,d is measuring range, here VA+VB=2.7V. Based on the formula (4), we get the value R2=280kThe output dc voltage is then connected to a 16 bits A/D converter 9015. The full scale output from AD598 is 4V analog. So the 800 arc-sec. is respected with about 25600 bits digit. In order to get stable reading, the converted bits are divided by 4. Therefore, 8 bit is equal to 1 arc-sec.Fig.4 AD598 for dual supply operation.Fig.5 Calibration and overall testing.4 Calibration and overall testThe calibration is shown in Fig.5. The dual-axis electronic level is set on a measuring fixture 4 which has been tested. When the fixture is working, there is about 0.10.2 arc-sec. of roll movement around the beam direction of the HP interferometer. The target of double retroreflectors is set on the fixture too. The HP interferomreter and part of the angle system are fixed on a stage with fixture 4 together. First, the instrument is calibrated against HP laser with the number of bits. After calibration, the equivalent values between bits and tilt angles are known. Therefore, the read-out of the instrument can be expressed by angle value. We use the same apparatus as shown in Fig.5 to do the overall testing. During testing the top plate of the fixture is upand down to make different angles through turning a screw. The testing data are listed intable 2.Table 2 gives out the testing data for positive direction and positive return direction of X axis of the electronic level. There are a set of data for minus direction and there are two sets of data for Y axis of the electronic level. All other testing results are the same as the data shown in Table 2. Based on the testing data, we can say that the maximum uncertainty of the instrument within 300 arc-sec. is better than 1 arc-sec.5 ConclusionThe new dual-axis electronic level has a simple mechanical structure, but high accuracy and feasible for using and adjustment. This achievement is owe to the compact mechanical body, a few integrated circuit chip with only several electronic external passive components engaged in the work, also owe to the quality of the plate spring, the better linearity of the LVDT, the satisfactory stability of the AD598 circuitry. Due to the dual-axis function plus double sets can be connected together to do a measuring project, the new electronic level can ensure a measuring process more reliable and more reasonable. So it is very useful and very easy for the wide applications in the field of industry.References1 Wang Baoguang , Mao Yunying. Study on the structure design of a high accuracy 3D probe. Journal of Tianjin University, 1993, (1):76842 Chen Lincai. Design of precision instrument. 1sted. Beijing: Mechanical Industry Express, 1991,3 Signal conditioning components & subsystem. Handbook, ANALOG DEVICES: 13234 Linear & angular displacement transducers. Hand-book, Company Lucas Schaevitz一种高精度的新型双坐标电子水平仪的研究摘要 介绍一种新型的高精度、双坐标、低成本电子水平仪的研究与开发。论述了其总体设计思想,并对机械、电子等主要参数的确定方法及精度检定等进行了深入的讨论。通过对仪器的实用性和精度指标的分析,表明该仪器在机床、汽车、飞机和轮船等制造领域有着广泛的应用前景。关键词: 电子水平仪 片簧 线性差动式变压器(LVDT) 倾斜角度测量1 引言型的双轴电子水平倾角传感器。这是一个独特的倾斜测量系统能够同时记录具有高的精度可达1弧秒的程度和方向的倾斜。 400弧秒的范围内，多达3个角秒。的范围内，为800弧秒。它有一个读数分辨率可达0.1角秒。仪器的工作原理如图1所示。它是由三部分组成。一个部分是相结合的支撑框架和基座。另一部分是静止的支持框架的顶部固定在工件5。第三部分是摆动工件2。工件5和2连接由一对3，测量，如果仪器上设置的表面是倾斜的双板弹簧，整体式结构的仪表会过于倾斜。但摆动工件2沿相反的方向移动，回到由重力倾斜。因此，线圈和铁心的LVDT（线性可变差动变压器）将有相对位移，并且将被转换为模拟电压输出的相对位移。对板簧导向的方式来保持工件摆动2移动。图1的结构的电子水平。由于仪器结构简单，无磨损，也没有交叉影响后的功能或精度。这是适合于广泛的领域中的质量保证和工程应用，给出了两个例子，如下所示。补偿的倾斜测量设备可以达到。使用仪器的另一头的目的，在上面的例子中是相同的。1.1检查平直度测量表Alpha示于图2（a）中的应用程序。单头的仪器上设置一个标准的三角形基地。在测量过程中，三角形的基础是对统治者步步移动。的每一步都是相等的三角形的一个边长。二维倾斜数据拿起由计算机中的每一步。仪器的另一头被设置在一个角落里测量表来监控整个表的变形。整个表的微变形一般是由连续移动的测试工具的重量。撤消修改图2应用实例。1.2监测水平或自动补偿的倾斜测量设备Alpha此应用程序的过程示于图2（b）。一个仪器头部的设置滑动阶段的测量仪器或机床。另一头的仪器测量设备的基础上。滑动台移动期间，两个导轨，俯仰和侧滚错误的尺寸误差，拿起由电脑自动进行。因此，要监视的水平或倾斜补偿的测量设备都可以到达。使用仪器的另一头的目的，在上面的例子中是相同的。2工作原理 在测量过程中，仪器的设置要被测量的表面上，并与三个螺丝8被调整到零指示。如果表面一个小角度倾斜时，角度的水平，然后摆动的部分将承受的力F和力偶M.随着多个F和M，Y的双板簧偏转的影响，将产生如图所示在图3中。它可以表示为式（1）： 图3 板弹簧的工作情况。这里：E为弹簧的弹性模量，I是转动惯量。也（b是宽度，h为弹簧的厚度）是已知的。因为倾斜角H是仅于800弧秒，F= Psincan被写为F = P。因此，该公式：当式（2），很明显的弹簧的挠度与倾斜角是线性的。假设仪器的绝对零度的仅仅是表示全球水平，然后将一个LVDT线圈的中重合的中心的核心。当倾斜的表面发生，这两个中心的铁心和线圈的相对移后的摆动部分。的倾斜角度大，将导致两个中心的距离长。 LVDT和其子系统AD598芯片将被转换成机械位移的双极性直流电压。3主系统的设计 在设计的过程中，重要的因素是控制和减少的滞后弹簧。为了达到这一要求，应遵循两个原则：首先，弹簧的材料应具有较小的滞后，所以我们选择了一种镍 - 钛 - 铝系列合金制成的弹簧，是更好地为这一要求。其次，在工作过程中，在最大偏转Y应该小于弹簧的最大弹性位移约45倍。弹簧的max最大弹性位移是： 在这里，是弹簧的弹性极限此外，考虑到整个大小的仪器，我们设置弹簧的长度L是60毫米的，宽度b=25mm时，厚度H =0.15毫米。根据式（2）及（3）中，我们设置他弹簧0.2毫米，= 8