Ulrasonic ranging sysem design综合课程设计翻译.doc

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1、Ultrasonic ranging system designPublication title: Sensor Review. Bradford: 1993. Vol. 13ABSTRACT：Ultrasonic ranging technology has wide using worth in many fields，such as the industrial locale，vehicle navigation and sonar engineeringNow it has been used in level measurement，self-guided autonomous v

2、ehicles, fieldwork robots automotive navigation，air and underwater target detection，identification，location and so onSo there is an important practicing meaning to learn the ranging theory and ways deeply. To improve the precision of the ultrasonic ranging system in hand，satisfy the request of the e

3、ngineering personnel for the ranging precision，the bound and the usage，a portable ultrasonic ranging system based on the single chip processor was developedKeywords：Ultrasound r，Ranging System，Single Chip Processor1.IntroductiveWith the development of science and technology, the improvement of peopl

4、es standard of living, speeding up the development and construction of the city. urban drainage system have greatly developed their situation is constantly improving. However, due to historical reasons many unpredictable factors in the synthesis of her time, the city drainage system. In particular d

5、rainage system often lags behind urban construction. Therefore, there are often good building excavation has been building facilities to upgrade the drainage system phenomenon. It brought to the city sewage, and it is clear to the city sewage and drainage culvert in the sewage treatment system. comf

6、ort is very important to peoples lives. Mobile robots designed to clear the drainage culvert and the automatic control system Free sewage culvert clear guarantee robot, the robot is designed to clear the culvert sewage to the core. Control System is the core component of the development of ultrasoni

7、c range finder. Therefore, it is very important to design a good ultrasonic range finder.2. A principle of ultrasonic distance measurement 2.1 The principle of piezoelectric ultrasonic generator Piezoelectric ultrasonic generator is the use of piezoelectric crystal resonators to work. Ultrasonic gen

8、erator, the internal structure as shown, 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 re

9、sonance, 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. The t

10、raditional way to determine the moment of the echos arrival is based on thresholding the received signal with a fixed reference. The 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 i

11、ntensity of an echo reflecting from an object strongly depends on the objects nature, size and distance from the sensor. Further, the 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 err

12、or may occur Even two echoes with different intensities arriving exactly at the same time will surpass the threshold at different moments. The stronger one will surpass the threshold earlier than the weaker, so it will be considered as belonging to a nearer object.2.2The principle of ultrasonic dist

13、ance 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 cl

14、ock. 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 3.Ultrasonic Ranging System for the Second Circuit Design System is characterized by single-chip

15、 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. Figure 1 circuit principle diagr

16、am3.1 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; ultra

17、sonic 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 transisto

18、r 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. 3.2 Reception and

19、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 osci

20、llator 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 proc

21、essing. 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 t

22、he 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 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;

23、 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 3.3 The

24、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 re

25、ceiver 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 i

26、ts 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 MOV 30H, A SETB EX0; open external interrupt

27、0 POP ACC POP PSW RETI For a flat target, a distance measurement consists of two phases: a coarse measurement and. a fine measurement:Step 1: Transmission of one pulse train to produce a simple ultrasonic wave.Step 2: Changing the gain of both echo amplifiers according to equation , until the echo i

28、s detected.Step 3: Detection of the amplitudes and zero-crossing times of both echoes.Step 4: Setting the gains of both echo amplifiers to normalize the output at, say 3 volts. Setting the period of the next pulses according to the : period of echoes. Setting the time window according to the data of

29、 step 2.Step 5: Sending two pulse trains to produce an interfered wave. Testing the zero-crossing times and amplitudes of the echoes. If phase inversion occurs in the echo, determine to otherwise calculate to by interpolation using the amplitudes near the trough. Derive t sub m1 and t sub m2 .Step 6

30、: Calculation of the distance y using equation .4. The ultrasonic ranging system software design Software is divided into two parts, the main program and interrupt service routine. Completion of the work of the main program is initialized, each sequence of ultrasonic transmitting and receiving contr

31、ol. 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. 5. Conclusions Required measuring range o

32、f 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

33、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, integrated amplifier, but also with automatic gain control level, magnification to 76dB, the center frequency

34、is 38k to 40k, is exactly resonant ultrasonic sensors frequencyREFERENCES1. Fox, J.D., Khuri-Yakub, B.T. and Kino, G.S., High Frequency Acoustic Wave Measurement in Air, in Proceedings of IEEE 1983 Ultrasonic Symposium, October 31-2 November, 1983, Atlanta, GA, pp. 581-4.2. Martin Abreu, J.M., Ceres

35、, R. and Freire, T., Ultrasonic Ranging: Envelope Analysis Gives Improved Accuracy, Sensor Review, Vol. 12 No. 1, 1992, pp. 17-21.3. Parrilla, M., Anaya, J.J. and Fritsch, C., Digital Signal Processing Techniques for High Accuracy Ultrasonic Range Measurements, IEEE Transactions: Instrumentation and

36、 Measurement, Vol. 40 No. 4, August 1991, pp. 759-63.4. Gao Guanwang,Wang Yanpeng,Sha Zhanyou,”The Design of Embedded MCU Network Measure and Control System”, Energy Procedia, Vol. 17, Part A, 2012, pp. 989-983.5. Canali, C., Cicco, G.D., Mortem, B., Prudenziati, M., and Taron, A., A Temperature Com

37、pensated Ultrasonic Sensor Operating in Air for Distance and Proximity Measurement, IEEE Transaction on Industry Electronics, Vol. IE-29 No. 4, 1982, pp. 336-41.6. Reinhardt Kotz, Johan Wiklund, Rainer Haldenwang,”Optimisation of Pulsed Ultrasonic Velocimetry system and transducer technology for industrial applications”, Ultrasonics, Vol.53, Issue 2, February 2013, pp. 469-459.7. Martin, J.M., Ceres, R., Calderon, L and Freire, T., Ultrasonic Ranging Gets Thermal Correction, Sensor Review, Vol. 9 No. 3, 1989, pp. 153-5.