外文翻譯--超聲波測距

附 錄 附錄 A: 英文文獻(xiàn)與中文參考譯文 Ultrasonic 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 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 provided 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. 一、 BACKGROUND OF THE INVENTION This invention relates to apparatus for the measurement of distance and, more particularly, to such 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 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 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 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,present invention to provide apparatus of the type described which is independent of temperature and humidity variations. 二、 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 includes 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 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 repetition 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. Since 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. 三、 BRIEF DESCRIPTION OF THE DRAWINGS The foregoing will be more readily apparent upon reading the following description in conjunction with the drawing in which the single FIGURE schematically depicts apparatus constructed in accordance with the principles of this invention. 四、 DETAILED DESCRIPTION Referring now to the drawing, there is shown a measuring unit 10 and a reference unit 12, both coupled to a utilization 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 pair 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 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, electrostatic, 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 amplifier 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 42 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 frequency 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 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 generator 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 the 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 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 18. 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 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 rate 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 12 is provided. The reference unit 12 is of the same construction as the measuring unit 10 and therefore includes 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 piezoelectric 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 pulse 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. Preferably, 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 distance D to be measured is related to the reference distance D R as follows: i D=D R (1/t R )/(1/t) where t R is the propagation time over the distance D R in the reference unit 12. This relationship is independent of both temperature and humidity. Thus, the outputs of the counters 46 and 78 are provided as inputs to the microprocessor 90 in the utilization means 14. The microprocessor 90 is appropriately programmed to provide an output which is proportional to the ratio of the outputs of the counters 46 and 78, which in turn are proportional to the repetition rates of the respective trigger pulse trains of the measuring unit 10 and the reference unit 12. As described, this ratio is independent of temperature and humidity and, since the reference distance D R is known, provides an accurate representation of the distance D. The utilization means 14 further includes a display 92 which is coupled to and controlled by the microprocessor 90 so that an operator can readily determine the distance D. Experiments have shown that when the 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 minimum distance, preferably about four inches. Accordingly, there has been disclosed improved apparatus for the measurement of distance utilizing ultrasonic waves. While an illustrative embodiment of the present invention has been disclosed herein, it is understood that various modifications and adaptations to the disclosed embodiment will be apparent to those of ordinary skill in the art and it is intended that this invention be limited only by the scope of the appended claims. 參考譯文 ： 超聲波測距 文件類型和數(shù)目：美國專利 5442592 摘要：提出了一種超聲波測距儀來抵消的影響溫度和濕度的變化，包括測量單元和參考資料。在每一個單位，重復(fù)的一系列脈沖的產(chǎn)生，每有一個重復(fù)率，直接關(guān)系到各自之間的距離，發(fā)射機(jī)和接收機(jī)。脈沖提供給各自的主機(jī)，和比例的反產(chǎn)出是利用確定的距離被衡量的。 出版日期： 1995 年 8月 15日 主審查員：羅保 .伊恩 j. 一、背景發(fā)明 本發(fā)明涉及 到儀器的測量距離，更特別是，這種儀器傳送超聲波兩點(diǎn)之間。 精密機(jī)床必須校準(zhǔn)。在過去，這已經(jīng)完成利用機(jī)械設(shè)備，如卡鉗，微米等。不過，使用這種裝置并不容易本身自動化技術(shù)。據(jù)了解，該兩點(diǎn)之間距離才能確定通過測量傳播時間的浪潮往返那些兩點(diǎn)。這樣一個類型的波是一種超聲波，或聲，海浪。當(dāng)超聲波旅行兩點(diǎn)之間，距離兩個點(diǎn)之間可以衡量乘以過境的時間波由波速，在中期分開兩點(diǎn)。因此，這是一個對象本發(fā)明提供儀器利用超聲波準(zhǔn)確測量兩點(diǎn)之間距離。 當(dāng)中等兩個點(diǎn)之間的間距是被衡量的是空氣，聲速是取決于溫度和空氣相對濕度。因此，它是進(jìn) 一步對象的，現(xiàn)在的發(fā)明，提供儀器的類型所描述的是獨(dú)立于溫度和濕度的變化。 二、綜述發(fā)明 前述的和額外的對象是達(dá)到了根據(jù)這些原則的這項(xiàng)發(fā)明提供距離測量儀器，其中包括一個參考的單位和測量單位。參考和測量單位是相同的，每個包括一電發(fā)射機(jī)和接收機(jī)一電。間隔發(fā)射器和接收器的參考股是一個固定的參考距離，而間距之間的發(fā)射機(jī)和接收機(jī)的測量單位是距離來衡量。在每一個單位，發(fā)射機(jī)和接收機(jī)是再加上由一個反饋環(huán)路導(dǎo)致發(fā)射機(jī)產(chǎn)生的聲脈沖是由接收機(jī)和轉(zhuǎn)換成一個電脈沖這是然后反饋到發(fā)射機(jī)，使重復(fù)一系列脈沖的結(jié)果。重復(fù)率脈沖是成反比關(guān)系 之間的距離發(fā)射器和接收器。在每一個單位，脈沖提供一個反。由于參考的距離是眾所周知，比例反產(chǎn)出是利用，以確定所期望的距離來衡量。由于這兩方面都是相同的影響，溫度和濕度的變化，采取的比例罪狀，由此產(chǎn)生的測量變得麻木等變化。 三、簡要說明圖紙 前述將更加明顯后，讀下列的說明，在與該繪圖并在其中單一數(shù)字schematically描繪儀器興建根據(jù)這些原則的這項(xiàng)發(fā)明。 四、詳細(xì)說明 談到現(xiàn)在的繪圖，有結(jié)果表明，測量單位和 10個參考單位 12個，均加上一個利用的手段 14 。測量單位包括 1 10電發(fā)射機(jī) 16日和 1電接收機(jī) 18 。變送器 16包括壓電材料 20夾心階層之間的對電極的 22日和 24日。同樣，接收機(jī)18個，包括壓電材料 26夾心階層之間的對電極的 28日和 30日。作為眾所周知，采用電場整個電極 22日和 24日，強(qiáng)調(diào)的是，誘導(dǎo)，在壓電材料 20 。如果該字段各有不同，如所申請的一個電脈沖，聲波是 32所產(chǎn)生的。為進(jìn)一步眾所周知，當(dāng)聲波影響到接收器 18 ，這誘導(dǎo)應(yīng)力，在壓電材料 26 ，導(dǎo)致一種電信號，以產(chǎn)生全國電極 28日和 30日。雖然壓電傳感器已說明，其他電聲裝置，可利用，例如，靜電，駐極體或電磁類型。 如表所示，電極 28日和 30日的接收 18 歲以下的耦合的投入一 34放大器，其輸出耦合輸入一個探測器 36 。探測器 36 是安排提供一個信號，脈沖前 38時，輸出放大器 34已經(jīng)超過預(yù)定的水平。脈沖前 38 ，然后產(chǎn)生一個觸發(fā)脈沖，這是提供給脈沖發(fā)生器 40 。在為了提高靈敏度，該系統(tǒng)，傳感器 16 和 18歲以下的共振興奮。有相應(yīng)的提供了一個連續(xù)波振蕩器 42提供了一個連續(xù)振蕩信號在一個固定的頻率，最好是共振頻率的傳感器 16和 18 。這個振蕩信號是提供給調(diào)制器 44 。要有效地激發(fā)發(fā)射機(jī) 16 ，可取的做法是提供幾個周期的共振頻率信號，而不是一個單脈沖或單周期 。因此，脈沖發(fā)生器 40是安排，在回應(yīng)的應(yīng)用存在的一個觸發(fā)脈沖，提供一個控制脈沖調(diào)制器 44有一個時間的平等的時間，時間預(yù)定人數(shù)的周期振蕩信號從振蕩器 42 。這個控制脈沖調(diào)制器的原因， 44個通過了 “ 水管爆裂 ” 的周期，以激發(fā)發(fā)射機(jī) 16 。 當(dāng)電力是適用于所描述的電路，有足夠的噪音在輸入到放大器 34 ，其輸出觸發(fā)脈沖發(fā)生器 40 至造成了一片叫好聲，振蕩周期，以提供整個電極 22日和24日的發(fā)射器 16 。變送器 16