超声波测距仪-毕业论文外文文献.docx

《超声波测距仪-毕业论文外文文献.docx》由会员分享，可在线阅读，更多相关《超声波测距仪-毕业论文外文文献.docx（15页珍藏版）》请在得力文库 - 分享文档赚钱的网站上搜索。

1、 淮 阴 工 学 院毕业设计(论文)外文资料翻译系 （院）：电子与电气工程学院专 业：测控技术与仪器姓 名： 学 号： 外文出处：United States Patent 5442592(用外文写)附 件：1.外文资料翻译译文；2.外文原文。指导教师评语：所选内容与课题相关，对课题设计参考具有一定价值；翻译具有一定难度，工作量适中；译文基本正确，语句通顺，但也存在部分错误。总体评价：良 年 月 日签名： 注：请将该封面与附件装订成册。附件1：外文资料翻译译文超声波测距仪文件类型和数目：美国专利5442592 摘要：提出了一种可以抵消温度的影响和湿度的变化的新型超声波测距仪，包括测量单元和参考资

2、料。在每一个单位，重复的一系列脉冲的产生，每有一个重复率，直接关系到各自之间的距离，发射机和接收机。该脉冲序列提供给各自的计数器，计数器的产出的比率，是用来确定被测量的距离。 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，最主要的是，这种仪器，其中两点之间传输超声波。精密机床必须校准。在过去，这已经利用机械设备来完成，如卡钳，微米尺等。不过，使用这种装置并不利于本身的自动化技术发展。据了解，两点之间的距离可以通过测量两点之间的行波传播时间的决定。这样的一个波浪型是一种超声波，或声波。当超声波在两点之间通过时，两点之间的距离可以由波的速度乘以测量

3、得到的在分离的两点中波中转的时间。因此，本发明提供仪器利用超声波来精确测量两点之间的距离对象。当任意两点之间的介质是空气时，声音的速度取决于温度和空气的相对湿度。因此，它是进一步的研究对象，本次的发明，提供的是独立于温度和湿度的变化的新型仪器。 二、 综述发明这项距离测量仪器发明是根据上述的一些条件和额外的一些基础原则完成的，其中包括一个参考单位和测量单位。参考和测量单位是相同的，每个包括一个超声波发射机和一个接收机。间隔发射器和接收器的参考值是一个固定的参考距离，而间距之间的发射机和接收机的测量单位是有最小距离来衡量的。在每一个单位，发射器和接收器耦合的一个反馈回路，它会导致发射器产生超声脉

4、冲，这是由接收器和接收到一个电脉冲然后被反馈到发射机转换，从而使重复系列脉冲的结果。重复率脉冲是成反比关系之间的距离发射器和接收器。在每一个单位，脉冲提供一个反馈。由于参考的距离是众所周知的声速，比例反产出是利用数学以确定所期望的距离来衡量。由于这两方面都是相同的影响，温度和湿度的变化，采取的比例相同，由此产生的测量变得准确。 三、详细说明(一)超声波测距原理 1、压电式超声波发生器原理压电式超声波发生器实际上是利用压电晶体的谐振来工作的。超声波发生器内部结构如下所示，它有两个压电晶片和一个共振板。当它的两极外加脉冲信号，其频率等于压电晶片的固有振荡频率时，压电晶片将会发生共振，并带动共振板振

5、动，便产生超声波。反之，如果两电极间未外加电压，当共振板接收到超声波时，将压迫压电晶片作振动，将机械能转换为电信号，这时它就成为超声波接收器了。测量脉冲到达时间的传统方法是以拥有固定参数的接收信号开端为基础的。这个界限恰恰选于噪音水平之上，然而脉冲到达时间被定义为脉冲信号刚好超过界限的第一时刻。一个物体的脉冲强度很大程度上取决于这个物体的自然属性尺寸还有它与传感器的距离。进一步说，从脉冲起始点到刚好超过界限之间的时间段随着脉冲的强度而改变。结果，一种错误便出现了两个拥有不同强度的脉冲在不同时间超过界限却在同一时间到达。强度较强的脉冲会比强度较弱的脉冲超过界限的时间早点，因此我们会认为强度较强的

6、脉冲属于较近的物体。2、超声波测距原理超声波发射器向某一方向发射超声波，在发射时刻的同时开始计时，超声波在空气中传播，途中碰到障碍物就立即返回来，超声波接收器收到反射波就立即停止计时。超声波在空气中的传播速度为340m/s，根据计时器记录的时间t，就可以计算出发射点距障碍物的距离(s)，即：s=340t/2二 超声波测距系统的电路设计系统的特点是利用单片机控制超声波的发射和对超声波自发射至接收往返时间的计时，单片机选用8751，经济易用，且片内有4K的ROM，便于编程。电路原理图如图所示。其中只画出前方测距电路的接线图，左侧和右侧测距电路与前方测距电路相同，故省略之。1、40kHz脉冲的产生与

7、超声波发射测距系统中的超声波传感器采用UCM40的压电陶瓷传感器，它的工作电压是40kHz的脉冲信号，这由单片机执行下面程序来产生。puzel： mov 14h, #12h； 超声波发射持续200mshere： cpl p1.0 ； 输出40kHz方波 nop ； nop ； nop ； djnz 14h，here； ret前方测距电路的输入端接单片机P1.0端口，单片机执行上面的程序后，在P1.0端口输出一个40kHz的脉冲信号，经过三极管T放大，驱动超声波发射头UCM40T，发出40kHz的脉冲超声波，且持续发射200ms。右侧和左侧测 距电路的输入端分别接P1.1和P1.2端口，工作原理

8、与前方测距电路相同。2、超声波的接收与处理接收头采用与发射头配对的UCM40R，将超声波调制脉冲变为交变电压信号，经运算放大器IC1A和IC1B两极放大后加至IC2。IC2是带有锁 定环的音频译码集成块LM567，内部的压控振荡器的中心频率f0=1/1.1R8C3，电容C4决定其锁定带宽。调节R8在发射的载频上，则LM567输入信号大于25mV，输出端8脚由高电平跃变为低电平，作为中断请求信号，送至单片机处理。前方测距电路的输出端接单片机INT0端口，中断优先级最高，左、右测距电路的输出通过与门IC3A的输出接单片机INT1端口，同时单片机P1.3和P1.4接到IC3A的输入端，中断源的识别由

9、程序查询来处理，中断优先级为先右后左。部分源程序如下：receive1：push psw push acc clr ex1 ； 关外部中断1 jnb p1.1, right ； P1.1引脚为0,转至右测距电路中断服务程序 jnb p1.2, left ； P1.2引脚为0,转至左测距电路中断服务程序return： SETB EX1； 开外部中断1 pop acc pop psw retiright： . ； 右测距电路中断服务程序入口 ajmp returnleft： . ； 左测距电路中断服务程序入口 ajmp return3、计算超声波传播时间在启动发射电路的同时启动单片机内部的定时器T

10、0，利用定时器的计数功能记录超声波发射的时间和收到反射波的时间。当收到超声波反射波时，接收电路 输出端产生一个负跳变，在INT0或INT1端产生一个中断请求信号，单片机响应外部中断请求，执行外部中断服务子程序，读取时间差，计算距离。其部分源程序如下：RECEIVE0： PUSH PSW PUSH ACC CLR EX0 ； 关外部中断0 MOV R7, TH0 ； 读取时间值 MOV R6, TL0 CLR C MOV A, R6 SUBB A, #0BBH； 计算时间差 MOV 31H, A ； 存储结果 MOV A, R7 SUBB A, #3CH MOV 30H, A SETB EX0

11、； 开外部中断0 POP ACC POP PSW RETI对于一个平坦的目标，距离测量包括两个阶段:粗糙的测量和精细测量。第一步：脉冲的传送产生一种简单的超声波。第二步：根据公式改变回波放大器的获得量直到回拨被检测到。第三步：检测两种回波的振幅与过零时间。第四步：设置回波放大器的所得来规格输出，假定是3伏。通过脉冲的周期设置下一个脉冲。根据第二部的数据设定时间窗。第五步：发射两串脉冲产生干扰波。测量过零时间与回波的振幅。如果逆向发生在回波中，决定要不通过在低气压插入振幅。第六步：通过公式计算距离y。四、超声波测距系统的软件设计软件分为两部分，主程序和中断服务程序，如图3（a）（b）(c) 所示

12、。主程序完成初始化工作、各路超声波发射和接收顺序的控制。定时中断服务子程序完成三方向超声波的轮流发射，外部中断服务子程序主要完成时间值的读取、距离计算、结果的输出等工作。系统初始化后就启动定时器T1从0开始计数，此时主程序进入等待，当到达定时时间时T1溢出进入T1中断服务子程序；在T1中断服务子程序中将启动一次新的超声波发射，此时将在P1.0引脚上开始产生的方波，同时开启定时器T0计时，为了避免直射波的绕射，需要延迟1ms后再开INT0中断允许；INT0中断允许打开后，若此时出现低电平则代表收到回波信号，将提出中断请求进入INT0中断服务子程序，在INT0中断服务子程序中将停止定时器T0计时，

13、读取定时器T0时间值到相应的存储区，同时设置接收成功标志；主程序一旦检测到接收成功标志，将调用测温子程序，采集超声波测距时的环境温度，并换算出准确的声速，存储到RAM存储单元中；单片机再调用距离计算子程序进行计算，计算出传感器到目标物体之间的距离；此后主程序调用显示子程序进行显示；当一次发射、接收、显示的过程完成后，系统将延迟100ms重新让T1置初值，再次启动T1以溢出，进入下一次测距。如果由于障碍物过远，超出量程，以致在T0溢出时尚未接收到回波，则显示“ERROR”重新回到主流程进入新一轮测试。五、结论对所要求测量范围30cm200cm内的平面物体做了多次测量发现，其最大误差为0.5cm，

14、且重复性好。可见基于单片机设计的超声波测距系统具有硬件结构简单、工作可靠、测量误差小等特点。因此，它不仅可用于移动机器人，还可用在其它检测系统中。思考：至于为什么接收不用晶体管做放大电路呢，因为放大倍数搞不好，CX20106集成放大电路，还带自动电平增益控制，放大倍数为76dB，中心频率是38k到40k，刚好是超声波传感器的谐振频率 。附件2：外文原文（复印件）Ultrasonic distance meter Document Type and Number:United States Patent 5442592 Abstract:An ultrasonic distance meter

15、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

16、 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. A.BACKGROUND OF THE INVENTION This invention relates to apparatus for

17、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

18、 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

19、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 m

20、easure 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 wh

21、ich is independent of temperature and humidity variations. B.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 an

22、d 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

23、 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 rep

24、etitive 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 determ

25、ine 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.C.DETAILED DESCRIPTION A.principle of ultrasonic distance measurement 1, t

26、he principle of piezoelectric ultrasonic generator Piezoelectric ultrasonic generator is the use of piezoelectric crystal resonators to work. Ultrasonic generator, the internal structure as shown in Figure 1, it has two piezoelectric chip and a resonance plate. When its two plus pulse signal, the fr

27、equency equal to the intrinsic piezoelectric oscillation frequency chip, the chip will happen piezoelectric resonance, and promote the development of plate vibration resonance, ultrasound is generated. Conversely, if the two are not inter-electrode voltage, when the board received ultrasonic resonan

28、ce, it will be for vibration suppression of piezoelectric chip, the mechanical energy is converted to electrical signals, then it becomes the ultrasonic receiver. The traditional way to determine the moment of the echos arrival is based on thresholding the received signal with a fixed reference. The

29、 threshold is chosen well above the noise level, whereas the moment of arrival of an echo is defined as the first moment the echo signal surpasses that threshold. The intensity of an echo reflecting from an object strongly depends on the objects nature, size and distance from the sensor. Further, th

30、e time interval from the echos starting point to the moment when it surpasses the threshold changes with the intensity of the echo. As a consequence, a considerable error may occur Even two echoes with different intensities arriving exactly at the same time will surpass the threshold at different mo

31、ments. The stronger one will surpass the threshold earlier than the weaker, so it will be considered as belonging to a nearer object.2, the principle of ultrasonic distance measurement Ultrasonic transmitter in a direction to launch ultrasound, in the moment to launch the beginning of time at the sa

32、me time, the spread of ultrasound in the air, obstacles on his way to return immediately, the ultrasonic reflected wave received by the receiver immediately stop the clock. Ultrasound in the air as the propagation velocity of 340m / s, according to the timer records the time t, we can calculate the

33、distance between the launch distance barrier (s), that is: s = 340t / 2 B.Ultrasonic Ranging System for the Second Circuit Design System is characterized by single-chip microcomputer to control the use of ultrasonic transmitter and ultrasonic receiver since the launch from time to time, single-chip

34、selection of 8751, economic-to-use, and the chip has 4K of ROM, to facilitate programming. Circuit schematic diagram shown in Figure 2. Draw only the front range of the circuit wiring diagram, left and right in front of Ranging Ranging circuits and the same circuit, it is omitted. 1,40 kHz ultrasoni

35、c pulse generated with the launch Ranging system using the ultrasonic sensor of piezoelectric ceramic sensors UCM40, its operating voltage of the pulse signal is 40kHz, which by the single-chip implementation of the following procedures to generate. puzel: mov 14h, # 12h; ultrasonic firing continued

36、 200ms here: cpl p1.0; output 40kHz square wave nop; nop; nop; djnz 14h, here; ret Ranging in front of single-chip termination circuit P1.0 input port, single chip implementation of the above procedure, the P1.0 port in a 40kHz pulse output signal, after amplification transistor T, the drive to laun

37、ch the first ultrasonic UCM40T, issued 40kHz ultrasonic pulse, and the continued launch of 200ms. Ranging the right and the left side of the circuit, respectively, then input port P1.1 and P1.2, the working principle and circuit in front of the same location. 2, reception and processing of ultrasoni

38、c Used to receive the first launch of the first pair UCM40R, the ultrasonic pulse modulation signal into an alternating voltage, the op-amp amplification IC1A and after polarization IC1B to IC2. IC2 is locked loop with audio decoder chip LM567, internal voltage-controlled oscillator center frequency

39、 of f0 = 1/1.1R8C3, capacitor C4 determine their target bandwidth. R8-conditioning in the launch of the carrier frequency on the LM567 input signal is greater than 25mV, the output from the high jump 8 feet into a low-level, as interrupt request signals to the single-chip processing. Ranging in fron

40、t of single-chip termination circuit output port INT0 interrupt the highest priority, right or left location of the output circuit with output gate IC3A access INT1 port single-chip, while single-chip P1.3 and P1. 4 received input IC3A, interrupted by the process to identify the source of inquiry to

41、 deal with, interrupt priority level for the first left right after. Part of the source code is as follows: receive1: push psw push acc clr ex1; related external interrupt 1 jnb p1.1, right; P1.1 pin to 0, ranging from right to interrupt service routine circuit jnb p1.2, left; P1.2 pin to 0, to the

42、left ranging circuit interrupt service routine return: SETB EX1; open external interrupt 1 pop acc pop psw reti right: .?; right location entrance circuit interrupt service routine Ajmp Return left: .; left Ranging entrance circuit interrupt service routine Ajmp Return 3, the calculation of ultrason

43、ic propagation time When you start firing at the same time start the single-chip circuitry within the timer T0, the use of timer counting function records the time and the launch of ultrasonic reflected wave received time. When you receive the ultrasonic reflected wave, the receiver circuit outputs

44、a negative jump in the end of INT0 or INT1 interrupt request generates a signal, single-chip microcomputer in response to external interrupt request, the implementation of the external interrupt service subroutine, read the time difference, calculating the distance . Some of its source code is as follows: RECEIVE0: PUSH PSW PUSH ACC CLR EX0; related external interrupt 0 MOV R7, TH0; read the time value MOV R6, TL0 CLR C MOV A, R6 SUBB A, # 0BBH; calculate the time difference MOV 31H, A; storage results MOV A, R7