毕业设计-超声波测距仪英文翻译.doc

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1、毕业设计(论文)外文资料翻译系 别： 电子信息系 专 业： 通信工程 班 级： B090310 姓 名： 李春健 学 号： B09031009 外文出处： 科技信息期刊 附 件： 1. 原文； 2. 译文 2013年03月7Ultrasonic distance meter Document Type and Number:United States Patent 5442592 Abstract:An ultrasonic distance meter cancels out the effects of temperature and humidity variations by incl

2、uding 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 provided to respective

3、 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 such apparatus w

4、hich 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 techniques. It

5、 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 points can be

6、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 between the two

7、 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,present invention to provide apparatus of the type described which is independent of temperature and humidity variations. 2、SUMMARY OF

8、 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 includes an electroacoustic tra

9、nsmitter 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 units, the transmitter and

10、 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 repetition rate of the pulses is

11、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. Since both counts are identica

12、lly 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 in conjunction with the d

13、rawing 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 and a reference unit , both coupled to a utilization means .The measuring unit inclu

14、des an electroacoustic transmitter and an electroacoustic receiver. The transmitter includes piezoelectric material sandwiched between a pair of electrodes and. Likewise, the receiver includes piezoelectric material sandwiched between a pair of electrodes and. As is known, by applying an electric fi

15、eld across the electrodes and, stress is induced in the piezoelectric material. If the field varies, such as by the application of an electrical pulse, an acoustic wave is generated. As is further known, when an acoustic wave impinges upon the receiver, this induces stress in the piezoelectric mater

16、ial which causes an electrical signal to be generated across the electrodes and. Although piezoelectric transducers have been illustrated, other electroacoustic devices may be utilized, such as, for example, electrostatic, electret or electromagnetic types. As shown, the electrodes and of the receiv

17、er are coupled to the input of an amplifier , whose output is coupled to the input of a detector. The detector is arranged to provide a signal to the pulse former when the output from the amplifier exceeds a predetermined level.The pulse former then generates a trigger pulse which is provided to the

18、 pulse generator .In order to enhance the sensitivity of the system, the transducers and are resonantly excited. There is accordingly provided a continuous wave oscillator which provides a continuous oscillating signal at a fixed frequency, preferably the resonant frequency of the transducers and. T

19、his oscillating signal is provided to the modulator . To effectively excite the transmitter, it is preferable to provide several cycles of the resonant frequency signal, rather than a single pulse or single cycle. Accordingly, the pulse generator is arranged, in response to the application thereto o

20、f a trigger pulse, to provide a control pulse to the modulator having a time duration equal the time duration of a predetermined number of cycles of the oscillating signal from the oscillator. This control pulse causes the modulator to pass a burst of cycles to excite the transmitter. When electric

21、power is applied to the described circuitry, there is sufficient noise at the input to the amplifier that its output triggers the pulse generator to cause a burst of oscillating cycles to be provided across the electrodes and of the transmitter. The transmitter accordingly generates an acoustic wave

22、 which impinges upon the receiver . The receiver then generates an electrical pulse which is applied to the input of the amplifier , which again causes triggering of the pulse generator. This cycle repeats itself so that a repetitive series of trigger pulses results at the output of the pulse former

23、. This pulse train is applied to the counter , as well as to the pulse generator. The transmitter and the receiver are spaced apart by the distance D which it is desired to measure. The propagation time t for an acoustic wave travelling between the transmitter and the receiver is given by: t=D/V s w

24、here V s is the velocity of sound in the air between the transmitter and the receiver. The counter 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

25、of the air, as follows: #EQU1# where T is the temperature, p is the partial pressure 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 ra

26、te of the trigger pulses is measured very accurately by the counter 46, the sound 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 is provided. The reference unit

27、is of the same construction as the measuring unit 10 and therefore includes an electroacoustic transmitter which includes piezoelectric material sandwiched between a pair of electrodes and, and an electroacoustic receiver which includes piezoelectric material sandwiched between a pair of electrodes

28、and. Again, transducers other than the piezoelectric type can be utilized. The transmitter and the receiver are spaced apart a known and fixed reference distance D R . The electrodes and are coupled to the input of the amplifier , whose output is coupled to the input of the detector. The output of t

29、he detector is coupled to the pulse former which generates trigger pulses. The trigger pulses are applied to the pulse generator which controls the modulator to pass bursts from the continuous wave oscillator to the transmitter. The trigger pulses from the pulse former are also applied to the counte

30、r. Preferably, all of the transducers, and have the same resonant frequency. Therefore, the oscillators and both operate at that frequency and the pulse generators and provide equal width output pulses. In usage, the measuring unit and the reference unit are in close proximity so that the sound velo

31、city in both of the units is the same. Although the repetition rates of the pulses in the measuring unit and the reference unit are each temperature and humidity dependent, it can be shown that the distance D to be measured is related to the reference distance D R as follows: i D=D R (1/t R )/(1/t)

32、where t R is the propagation time over the distance D R in the reference unit. This relationship is independent of both temperature and humidity. Thus, the outputs of the counters and are provided as inputs to the microprocessor in the utilization means. The microprocessor is appropriately programme

33、d to provide an output which is proportional to the ratio of the outputs of the counters, which in turn are proportional to the repetition rates of the respective trigger pulse trains of the measuring unit and the reference unit. As described, this ratio is independent of temperature and humidity an

34、d, since the reference distance D R is known, provides an accurate representation of the distance D. The utilization means further includes a display which is coupled to and controlled by the microprocessor so that an operator can readily determine the distance D. Experiments have shown that when th

35、e distance between the transmitting and receiving transducers is too small, reflections of the acoustic wave at the transducer surfaces has a not insignificant effect which degrades the measurement accuracy. Accordingly, it is preferred that each transducer pair be separated by at least a certain mi

36、nimum distance, preferably about four inches. 超声波测距仪文件类型和数目：美国专利5442592 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

37、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

38、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

39、度和湿度引起的变化一样是没有办法避免的。三、简要说明图纸通过接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，测量单元和参考单元都联结起来组成了可以利用的单元。测量单元包括了一个电信号发射机和一个电信号接收机。发射器包括了夹着一对电极和压电材料。同样，接收机包括了夹着一对电极和压电材料。众所周知，通过利用电极之间产生的电场，压电材料将产生压力。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。因此，进一步得知，当声波对接收器起作用的时候，这时会引起接收器上的压变材料产生机械变形

40、，同时产生一个电信号通过电极。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，接收机的电极和将与放大器的输入端相连接，同时，放大器的其输出端与探测器相连接。探测器被用于提供一个信号给脉冲发生器，当放大器的输出已经超过预定的等级。脉冲发生器然后产生一个触发脉冲，这是提供给脉冲发生器。在为了提高灵敏度，该系统的传感器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，他能持续的产生一个固定频率的连续振荡信号，最好是同传感器和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。为了使发射机有效的工作，最好的做法是提供

41、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，用于回应每一个触发脉冲，提供一个控制脉冲给调制器，让调制器有一个与来自于振荡器的周期振荡信号预定的相同时间。这样的控制脉冲能使调制器传送一个周期的突破口以触发发射机。当电源被用于描述的电路，有相当大的噪音输入到放大器，以至于其输出触发脉冲发生器引起正当周期变化，这个振荡周期是用来提供给发射器的电极和。发射器因此产生声波并作用于接收器。接收器1然后产生一个电脉冲，输入放大器，这再次触发脉冲发生器。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的输出。这脉冲串被用于计数器，以及脉冲发生器。发射机和接收机中间的

42、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，通过公式T=D/V。速度是在发射机和接收机之间这段空气中传播的速度，计数器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。参考单元同测量单元基本上是一样的，其中，包括一电

43、发射机，以及在压电材料之间的一对电极和接收机，其中包括压电材料之间的一对电极。再次，传感器除了其他类型压电也可以被利用。发射机和接收机之间的距离都是已知的且固定的,设为DR。电极和连接到放大器的输入端，其输出连接到探测器。探测器的输出端连接到脉冲发生器，脉冲发生器产生触发脉冲。触发脉冲应用到脉冲发生器以控制调制器通过连续振荡器传送一段脉冲串传递至发射机。来自于脉冲发生器的触发脉冲也用于计数器。最好是所有的传感器具有相同的共振频率。因此，振荡器都工作在同样的频率上，脉冲发生器产生相同带宽的输出脉冲。按照惯例，测量单元和参考单元空间上很接近，使该声速在这两个单元是相同的。虽然测量单元和参考单元的脉

44、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：iD=DR(1/tR)/(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，计数器的输出被用来提供来作为微处理器，作为方法。微处理器可通过编写程序来提供输出。这个输出与计数器的输出是成比例的，反过来也同测量单元和参考单元各自的触发脉冲串成比例。如所叙述的一样，这些比率是不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。这个利用方法更进一步的包括了被微处理器控制的显示器，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。