外文翻译--超声波测距系统

附 录 2 This article described the three directions (before, left, right) ultrasonic ranging system is to understand the front of the robot, left and right environment to provide a movement away from the information. (Similar to GPS Positioning System) A principle of ultrasonic distance measurement 1, the 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 frequency 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 resonance, it will be for vibration suppression of piezoelectric chip, the mechanical energy is converted to electrical signals, then it becomes the ultrasonic receiver. 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 same 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 distance between the launch distance barrier (s), that is: s = 340t / 2 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 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. 2 1,40 kHz ultrasonic 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 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 launch 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 ultrasonic 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 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 front 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 deal with, interrupt priority level for the first left right after. Part of the source code is as follows: receive1: push psw push acc 3 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 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 4, the calculation of ultrasonic 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 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 SUBB A, # 3CH 4 MOV 30H, A? SETB EX0； open external interrupt 0 POP ACC? POP PSW RETI Fourth, the ultrasonic ranging system software design Software is divided into two parts, the main program and interrupt service routine, shown in Figure 3 (a) (b) (c) below. Completion of the work of the main program is initialized, each sequence of ultrasonic transmitting and receiving control. Interrupt service routines from time to time to complete three of the rotation direction of ultrasonic launch, the main external interrupt service subroutine to read the value of completion time, distance calculation, the results of the output and so on. V. CONCLUSIONS Required measuring range of 30cm 200cm objects inside the plane to do a number of measurements found that the maximum error is 0.5cm, and good reproducibility. Single-chip design can be seen on the ultrasonic ranging system has a hardware structure is simple, reliable, small features such as measurement error. Therefore, it can be used not only for mobile robot can be used in other detection systems. Thoughts: As for why the receiver do not have the transistor amplifier circuit, because the magnification well, CX20106 integrated amplifier, but also with automatic gain control level, magnification to 76dB, the center frequency is 38k to 40k, is exactly resonant ultrasonic sensors frequency 5 本文所介绍的三方向（前、左、右）超声波测距系统，就是为机器人了解其前方、左侧和右侧的环境而提供一个运动距离 信息。（类似 GPS定位系统） 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图 1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。 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 2 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 200ms here： cpl p1.0 ； 输出 40kHz方波 nop ； nop ； nop ； djnz 14h， here； ret 6 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