超声波测距仪外文翻译1

1、 淮 阴 工 学 院毕业设计(论文)外文资料翻译学 院：电子与电气工程学院专 业：电子信息工程姓 名：仲林学 号：3082107140外文出处：advances in imaging and electron physics附 件：1.外文资料翻译译文；2.外文原文。指导教师评语： 年月日签名： 附件1：外文资料翻译译文超声波测距仪摘要：提出了一种超声波测距仪来抵消的温度和湿度引起的变化，包括测量单元和参考标准。每一个单元产生重复的一系列脉冲，每一次重复直接关系到发射机和接收机之间的距离。脉冲串提供给各自的计数器，然后利用计数器所测得的数据进行距离的测量。 出版日期： 1995年8月15日主审

2、查员：罗保.伊恩j. 一、背景发明本发明涉及到仪器的测量距离，更特别是，这种仪器传送超声波于两点之间。 精密机器设备必须校准。在过去，这已经可以利用卡钳，微米等工具来校准机械设备。不过，使用这些工具都不能实现自动化。据了解，该两点之间距离可以通过测量波在两点之间的传播时间来确定。这样一个类型的波可以是是一种超声波，或声，或波。当超声波传播于两点之间的时候，两个点之间的距离可以通过由超声波波速乘以超声波传播的时间，在合适的分离的两点。因此，这是一个发明提供仪器利用超声波准确测量两点之间距离的方法。 当距离适当的两个点之间的介质是空气的时候，声速只取决于温度和空气相对湿度。因此，这个发明的进一步目

3、标是，目前的发明提供仪器的方法如所描述的一样是独立于温度和湿度的变化的。 二、综述发明 前述的和额外的目标已经实现了根据这些原则的这项发明提供距离测量仪器，其中包括一个参考的单元和测量单元。参考和测量单元是相同的，每个单元都包括了一个电声波的发射机和接收机。参考单元的发射器和接收器之间的间隔是一个固定的参考距离，然而测量单元的发射机和接收机的间距才是我们所要测量的部分。在每一个单元中，发射机和接收机都连接了一个反馈环路，以使发射机产生能由接收器接收的声波生脉冲，然后由接收机转换成一个电脉冲反馈到发射机，使产生一系列重复脉冲的结果。脉冲重复率是成反比关系发射器和接收器之间的距离。在每一个单元，脉

4、冲被用来提供给一个计数器。由于参考的距离是已经知道的了，所以计数器所输出的数据被利用来确定所期望测得的距离。由于温度和湿度的变化，这两方面都会造成相同的影响，利用计数器所提供的数据，这样的测量对于温度和湿度引起的变化一样是没有办法避免的。 三、简要图纸说明 通过读接了下来的说明前面的叙述将变得更加明显，这个关于电路原理图的描述在与这项发明的相关规律保持了相当的一致性。 四、详细说明根据现在的绘图，可以得出以下结论，测量单元10和参考单元12都联结起来组成了可以利用的单元14 。测量单元10包括了一个电信号发射机16和一个电信号接收机18 。发射器16包括了夹着一对电极22和24的压电材料20。

5、同样，接收机18包括了夹着一对电极28和30的压电材料26。众所周知，通过利用电极22和24之间产生的电场，压电材料20将产生压力 。如果该电场产生变化的话，例如通过利用一个电脉冲，就会产生一个声波32。因此，进一步得知，当声波对接收器18起作用的时候 ，这时会引起接收器上的压变材料26产生机械变形，同时产生一个电信号通过28和30这一对电极 。虽然已经对压电传感器作出了说明，但是其他的电声装置也可利用，例如，有关静电的，驻极体或电磁类型的。 如图所示，接收机的电极28和30将与放大器34的输入端相连接，同时，放大器的其输出端与探测器36相连接。探测器36被用于提供一个信号给脉冲发生器38，当

6、放大器34的输出已经超过预定的等级。脉冲发生器38然后产生一个触发脉冲，这是提供给脉冲发生器40 。在为了提高灵敏度，该系统的传感器16和18岁通常情况下都是保持运作的。根据相应的需要，本发明提供了一个连续波振荡器42，他能持续的产生一个固定频率的连续振荡信号，最好是同传感器16和18能接收到的固定频率一致 。这个振荡信号被用来提供给调制器44 。为了使发射机16有效的工作 ，最好的做法是提供几个周期的共振频率信号，而不是一个单脉冲或单周期。因此，在这里使用了脉冲发生器40，用于回应每一个触发脉冲，提供一个控制脉冲给调制器44，让调制器44有一个与来自于振荡器42的周期振荡信号预定的相同时间

7、。这样的控制脉冲能使调制器44传送一个周期的突破口以触发发射机16。 当电源被用于描述的电路，有相当大的噪音输入到放大器34 ，以至于其输出触发脉冲发生器40引起正当周期变化，这个振荡周期是用来提供给发射器16的电极22和24。发射器16因此产生声波32并作用于接收器18 。接收器18 然后产生一个电脉冲，输入放大器的34 ，这再次触发脉冲发生器40 。这个周期继续循环，使重复的一系列触发脉冲作用于脉冲发生器38的输出 。这脉冲串被用于计数器46，以及脉冲发生器40 。 发射机16和接收机18中间的间隔距离 d 它是我们想要测量的数据。传播时间t是声波传播于之间的距离除以速度而得出来的，通过公

8、式t=d/v 。速度是在发射机16和接收机18之间这段空气中传播的速度，计数器46测量触发脉冲的重复率，这是因为脉冲等于的1/t。因此，重复率是等于v/d。声波的速度通常受到空气的湿度和温度的影响，例子如下：#equ1#其中t是温度，p是水汽局部的压力，h是大气压强， 和是比例不同压力下在热水汽和干燥的空气不同的比热容。因此，触发脉冲的重复率测被计数器46测量得相当的准确 ，但是声速受到温度和湿度的影响，使测量的距离d无法被准去的确定。 根据这项发明的基本原理，需要利用参考单元12 。参考单元12同测量单元10基本上是一样的，其中，包括一电发射机50，以及在压电材料52之间的一对电极的54和5

9、6 。接收机58 ，其中包括压电材料60之间的一对电极62和64 。再次，传感器除了其他类型压电也可以被利用。发射机50和接收机58之间的距离都是已知的且固定的,设为dr。电极62和64连接到放大器66的输入端 ，其输出连接到探测器68 。探测器68的输出端连接到脉冲发生器70，脉冲发生器70产生触发脉冲。触发脉冲应用到脉冲发生器72以控制调制器74通过连续振荡器76传送一段脉冲串传递至发射机50 。来自于脉冲发生器70的触发脉冲也用于计数器78。 最好是所有的传感器16 ，18 ，50和58具有相同的共振频率。因此，振荡器42和76都工作在同样的频率上，脉冲发生器40和72产生相同带宽的输出

10、脉冲。 按照惯例，测量单元10和参考单元12空间上很接近，使该声速在这两个单元是相同的。虽然测量单元10和参考单元12的脉冲重复率各自依赖于各自的温度和湿度，能证明的距离d来衡量。可以得出测量单元和参考单元之间的联系如下：i d=d r (1/t r )/(1/t)，tr是指的参照单元声波传播于固定空间的时间。这个关系与空气的温度和湿度都是无关的。 因此，计数器46和计数器78的输出被用来提供来作为微处理器90，作为方法14。微处理器90可通过编写程序来提供输出。这个输出与计数器46和78的输出是成比例的，反过来也同测量单元10和参考单元12各自的触发脉冲串成比例。如所叙述的一样，这些比率是不

11、依赖于温度和湿度的，因为参考距离dr是已知的，提供了一个准确的距离d的参考。这个利用方法12更进一步的包括了被微处理器控制的显示器92，所以设备可以确定距离d。试验还表明当发射机和接收机传感器之间的距离太小的时候，声波的反射在传感器表面的效果不是很明显，以至于极大的影响了测量的精度。根据这种情况，使传感器分开有一个相当的最小距离，最合适是4英寸。附件2：外文原文ultrasonic distance meterabstract:an ultrasonic distance meter cancels out the effects of temperature and humidity var

12、iations by including a measuring unit and a reference unit. in each of the units, a repetitive series of pulses is generated, each having a repetition rate directly related to the respective distance between an electroacoustic transmitter and an electroacoustic receiver. the pulse trains are provide

13、d to respective counters, and the ratio of the counter outputs is utilized to determine the distance being measured. publication date:08/15/1995 primary examiner:lobo, ian j.1、background of the invention this invention relates to apparatus for the measurement of distance and, more particularly, to s

14、uch apparatus which transmits ultrasonic waves between two points. precision machine tools must be calibrated. in the past, this has been accomplished utilizing mechanical devices such as calipers, micrometers, and the like. however, the use of such devices does not readily lend itself to automation

15、 techniques. it is known that the distance between two points can be determined by measuring the propagation time of a wave travelling between those two points. one such type of wave is an ultrasonic, or acoustic, wave. when an ultrasonic wave travels between two points, the distance between the two

16、 points can be measured by multiplying the transit time of the wave by the wave velocity in the medium separating the two points. it is therefore an object of the present invention to provide apparatus utilizing ultrasonic waves to accurately measure the distance between two points. when the medium

17、between the two points whose spacing is being measured is air, the sound velocity is dependent upon the temperature and humidity of the air. it is therefore a further object of the invention, present invention to provide apparatus of the type described which is independent of temperature and humidit

18、y variations. 2、summary of the invention the foregoing and additional objects are attained in accordance with the principles of this invention by providing distance measuring apparatus which includes a reference unit and a measuring unit. the reference and measuring units are the same and each inclu

19、des an electroacoustic transmitter and an electroacoustic receiver. the spacing between the transmitter and the receiver of the reference unit is a fixed reference distance, whereas the spacing between the transmitter and receiver of the measuring unit is the distance to be measured. in each of the

20、units, the transmitter and receiver are coupled by a feedback loop which causes the transmitter to generate an acoustic pulse which is received by the receiver and converted into an electrical pulse which is then fed back to the transmitter, so that a repetitive series of pulses results. the repetit

21、ion rate of the pulses is inversely related to the distance between the transmitter and the receiver. in each of the units, the pulses are provided to a counter. since the reference distance is known, the ratio of the counter outputs is utilized to determine the desired distance to be measured. sinc

22、e both counts are identically influenced by temperature and humidity variations, by taking the ratio of the counts, the resultant measurement becomes insensitive to such variations. 3、brief description of the drawings the foregoing will be more readily apparent upon reading the following description

23、 in conjunction with the drawing in which the single figure schematically depicts apparatus constructed in accordance with the principles of this invention. 4、detailed description referring now to the drawing, there is shown a measuring unit 10 and a reference unit 12, both coupled to a utilization

24、means 14. the measuring unit 10 includes an electroacoustic transmitter 16 and an electroacoustic receiver 18. the transmitter 16 includes piezoelectric material 20 sandwiched between a pair of electrodes 22 and 24. likewise, the receiver 18 includes piezoelectric material 26 sandwiched between a pa

25、ir of electrodes 28 and 30. as is known, by applying an electric field across the electrodes 22 and 24, stress is induced in the piezoelectric material 20. if the field varies, such as by the application of an electrical pulse, an acoustic wave 32 is generated. as is further known, when an acoustic

26、wave impinges upon the receiver 18, this induces stress in the piezoelectric material 26 which causes an electrical signal to be generated across the electrodes 28 and 30. although piezoelectric transducers have been illustrated, other electroacoustic devices may be utilized, such as, for example, e

27、lectrostatic, electret or electromagnetic types. as shown, the electrodes 28 and 30 of the receiver 18 are coupled to the input of an amplifier 34, whose output is coupled to the input of a detector 36. the detector 36 is arranged to provide a signal to the pulse former 38 when the output from the a

28、mplifier 34 exceeds a predetermined level. the pulse former 38 then generates a trigger pulse which is provided to the pulse generator 40. in order to enhance the sensitivity of the system, the transducers 16 and 18 are resonantly excited. there is accordingly provided a continuous wave oscillator 4

29、2 which provides a continuous oscillating signal at a fixed frequency, preferably the resonant frequency of the transducers 16 and 18. this oscillating signal is provided to the modulator 44. to effectively excite the transmitter 16, it is preferable to provide several cycles of the resonant frequen

30、cy signal, rather than a single pulse or single cycle. accordingly, the pulse generator 40 is arranged, in response to the application thereto of a trigger pulse, to provide a control pulse to the modulator 44 having a time duration equal the time duration of a predetermined number of cycles of the

31、oscillating signal from the oscillator 42. this control pulse causes the modulator 44 to pass a burst of cycles to excite the transmitter 16. when electric power is applied to the described circuitry, there is sufficient noise at the input to the amplifier 34 that its output triggers the pulse gener

32、ator 40 to cause a burst of oscillating cycles to be provided across the electrodes 22 and 24 of the transmitter 16. the transmitter 16 accordingly generates an acoustic wave 32 which impinges upon the receiver 18. the receiver 18 then generates an electrical pulse which is applied to the input of t

33、he amplifier 34, which again causes triggering of the pulse generator 40. this cycle repeats itself so that a repetitive series of trigger pulses results at the output of the pulse former 38. this pulse train is applied to the counter 46, as well as to the pulse generator 40. the transmitter 16 and

34、the receiver 18 are spaced apart by the distance d which it is desired to measure. the propagation time t for an acoustic wave 32 travelling between the transmitter 16 and the receiver 18 is given by: t=d/v s where v s is the velocity of sound in the air between the transmitter 16 and the receiver 1

35、8. the counter 46 measures the repetition rate of the trigger pulses, which is equal to 1/t. therefore, the repetition rate is equal to v s /d. the velocity of sound in air is a function of the temperature and humidity of the air, as follows: #equ1# where t is the temperature, p is the partial press

36、ure of the water vapor, h is the barometric pressure, w and a are the ratio of constant pressure specific heat to constant volume specific heat for water vapor and dry air, respectively. thus, although the repetition rate of the trigger pulses is measured very accurately by the counter 46, the sound

37、 velocity is influenced by temperature and humidity so that the measured distance d cannot be determined accurately. in accordance with the principles of this invention, a reference unit 12 is provided. the reference unit 12 is of the same construction as the measuring unit 10 and therefore includes

38、 an electroacoustic transmitter 50 which includes piezoelectric material 52 sandwiched between a pair of electrodes 54 and 56, and an electroacoustic receiver 58 which includes piezoelectric material 60 sandwiched between a pair of electrodes 62 and 64. again, transducers other than the piezoelectri

39、c type can be utilized. the transmitter 50 and the receiver 58 are spaced apart a known and fixed reference distance d r . the electrodes 62 and 64 are coupled to the input of the amplifier 66, whose output is coupled to the input of the detector 68. the output of the detector 68 is coupled to the p

40、ulse former 70 which generates trigger pulses. the trigger pulses are applied to the pulse generator 72 which controls the modulator 74 to pass bursts from the continuous wave oscillator 76 to the transmitter 50. the trigger pulses from the pulse former 70 are also applied to the counter 78. prefera

41、bly, all of the transducers 16, 18, 50 and 58 have the same resonant frequency. therefore, the oscillators 42 and 76 both operate at that frequency and the pulse generators 40 and 72 provide equal width output pulses. in usage, the measuring unit 10 and the reference unit 12 are in close proximity so that the sound velocity in both of the units is the same. although the repetition rates of the pulses in the measuring unit 10 and the reference unit 12 are each temperature and humidity dependent, it can be shown that the