CN203299224U - Motor vehicle speed detection device based on piezoelectric sensor - Google Patents
Motor vehicle speed detection device based on piezoelectric sensor Download PDFInfo
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- CN203299224U CN203299224U CN2013203156436U CN201320315643U CN203299224U CN 203299224 U CN203299224 U CN 203299224U CN 2013203156436 U CN2013203156436 U CN 2013203156436U CN 201320315643 U CN201320315643 U CN 201320315643U CN 203299224 U CN203299224 U CN 203299224U
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Abstract
Provided is a motor vehicle speed detection device based on piezoelectric sensors. The device comprises a first piezoelectric sensor, a second piezoelectric sensor, an I/O input buffer, a main controller, a timing pulse generator, a display data latch, a display bit strobe latch, an integrated nixie display, an LED lamp driver, and an LED indicator lamp. The first piezoelectric sensor and the second piezoelectric sensor are buried in vehicle travel roads which have constant space. The device is an intelligent traffic and illegal capture evidence obtaining system, and a novel economical and accurate motor vehicle speed detection scheme is provided. The device is controlled by the singlechip, and detects speed of a motor vehicle combining with the piezoelectric sensors. The device combines the piezoelectric sensor technology and the cheap singlechip, and is economical and practical as an annular coil, and disadvantages of low motor vehicle speed detection precision and large error of the annular coil are overcome. The device can obtain speed values of high precision detection as a radar, and the price is more economical and practical than that of a radar product.
Description
Technical field
The utility model relates to electronic technology field, is specifically related to a kind of pick-up unit of motor vehicle speed based on piezoelectric transducer.
Background technology
Along with the quick increase with the magnitude of traffic flow of being on the increase of motor vehicle, the motor vehicle speed detection technique in intelligent transportation and motor vehicle violation snap-shooting system, is a very important part.The sensor of motor vehicle speed pick-up unit, according to adopting different technologies mainly to be divided into: conventional several detection modes such as Data mining, video detection, microwave radar, laser radars.
The Data mining mode is a kind of motor vehicle detecting technology of comparative maturity, and it is mainly a kind of for the existence of motor vehicle or the detection mode of passing through.But, due to the defect of himself, can't obtain accurate, high-precision velocity amplitude during the method detection speed.
The detection of toroid winding speed is normally completed by two toroid windings, record motor vehicle through the first toroid winding and the second toroidal time, then utilize the distance between the first toroid winding and the second toroid winding, obtain the speed of motor vehicle according to V=S/T.Uncertainty due to the motor-driven vehicle going track, as: non-rectilinear travel, non-ly at the uniform velocity travel, the factor such as surrounding magnetic field effect, toroid winding shape, size, often make former and later two toroid windings consistent not to the detection of same car, thereby cause the vehicle running speed that obtains and actual speed deviation excessive, defects such as easily occurring leaking car, emit at a high speed, emit low speed, rate accuracy is low.Produced also thus that mistake is grabbed, the phenomenons such as erroneous judgement and legal dispute.
The video detection mode is a kind of method of utilizing image processing techniques to realize Vehicle Speed Measurement Through Video.Collection by video image has realized the speed of the motor vehicle in travelling is detected, pass through the image data post-processed: the methods such as background estimating, motion detection, Target Segmentation, target location are determined, target following, utilize corresponding computing method and computing formula, calculate the speed of motor vehicle.The precision of the motor vehicle speed of video detection at present is also very poor, is mainly because video detects the factors such as extraneous complicated scenery, ambient light variation, installation site that are subjected to.Simultaneously, need to gather in large quantities video image and relevant mathematical computations, take many times.Therefore keep away and unavoidably produced velocity error.The velocity amplitude of its detection can only, as the data reference, can not use as high-quality metering outfit.
At present all to the checkout equipment aspect motor vehicle speed in, the rate accuracy of microwave radar, laser radar is best product.
It is mainly to utilize Doppler effect (Doppler Effect) principle that microwave radar tests the speed: when target was close to radar antenna, the reflected signal frequency will be higher than transmitter frequency; Otherwise when target was gone away from antenna, the reflected signal frequency will can change by the numerical value of frequency lower than transmitter frequency, calculates the relative velocity of target and radar.
It is the product that laser technology combines with Radar Technology that laser radar tests the speed.Comprise a single bundle narrow band laser and a receiving system.Because the light velocity is fixing, laser pulse is sent to the time that target turns back again and can be directly proportional to distance., with two pulses of fixed intervals emission, can record two distances; The difference of these two distances can be obtained the speed of target divided by Transmission Time Interval.In theory, emission two subpulses can measure speed; In fact, for avoiding mistake, survey, laser radar velometer (rifle) was launched and is asked its mean value calculation target velocity up to the pulsating wave of seven groups in moment.
Microwave radar, laser radar test the speed and existing be widely used in the police and exceed the speed limit in the industry such as test.But due to the problem that relative price is more expensive and install, major part is to be used in mobile candid photograph equipment.Simultaneously testing the speed of radar is target detection to a section, and the single track that can not differentiate a section, so its practicality has been subject to restriction greatly.
Piezoelectric transducer is a kind of sensor based on piezoelectric effect of newly developing in recent years, is a kind of self-power generation type and data-collection formula sensor.Its sensitive element is made by piezoelectric, produces electric charge on its surface after piezoelectric is stressed, and this electric charge after charge amplifier, testing circuit amplification and transforming impedance, just becomes the electric weight output that is proportional to suffered external force.
Piezoelectric transducer is for detection of power and the non-electric physical quantity that can be transformed to power, as pressure, acceleration etc.Its advantage is bandwidth, highly sensitive, signal to noise ratio (S/N ratio) is high, simple in structure, reliable operation and lightweight etc.It is widely used in the technical fields such as engineering mechanics, biomedicine, electroacoustics.
The application of existing piezoelectric transducer, be in the stage at the early-stage in China, is take the road dynamic weighing as main substantially, as overload punishing justification violating the regulations, and as pure motor vehicle speed, detects also seldom.
Being compared as follows of piezoelectric transducer and toroid winding, detections of radar mode:
Piezoelectric transducer is substantially the same with the toroid winding installation method, need to be embedded in the road of motor-driven vehicle going.But with very large difference is still arranged on toroidal use-pattern.
Difference one: shape is installed
Toroid winding is that the shape modes such as rectangle, rhombus, the positive Eight characters are installed, and piezoelectric transducer to be fillet shape mode install, the contrast of both mounting meanss is as shown in Figure 7.So latter's error on the speed accuracy of detection is minimum.
Difference two: detection mode
Data mining mode: when motor vehicle is arranged through toroid winding, changed original normal toroid winding surrounding magnetic field, the frequency of toroid winding oscillatory circuit is changed.Utilize this rate of change to reach order ground to motor vehicle detecting.Need A/D sampling and filtering to calculate.Cycle is long, error is large.
The piezoelectric transducer detection mode: when having motor vehicle to pass through piezoelectric transducer respectively, piezoelectric transducer is being subject to after external pressure triggers just producing immediately electric pulse, the I/O signal that can identify as computing machine after amplification, shaping circuit are processed.Therefore, piezoelectric transducer is faster than toroid winding on response speed.
Piezoelectric transducer is compared its accuracy of detection with radar basically identical, but the piezoelectric transducer cost is compared really and is dominant than radar with cost.Piezoelectric transducer can carry out to the motor vehicle in single track speed and detect.Can accurately to motor vehicle, capture location.But radar does not really reach this requirement.
Therefore, in above-mentioned motor vehicle speed detected, piezoelectric transducer namely had the high precision of radar, and has with respect to toroidal economic and practical.
Summary of the invention
For the problem that prior art exists, the utility model provides a kind of pick-up unit of motor vehicle speed based on piezoelectric transducer.
The technical solution of the utility model is:
A kind of pick-up unit of motor vehicle speed based on piezoelectric transducer, comprise the first piezoelectric transducer, the second piezoelectric transducer, I/O input buffer, master controller, timing pulse generator, demonstration data latches, show position gating latch, integrated nixie display, LED lamp driver and LED light;
the first piezoelectric transducer and the second piezoelectric transducer are embedded in the motor-driven vehicle going road of constant spacing, the output terminal of the output terminal of the first piezoelectric transducer and the second piezoelectric transducer all is connected to the input end of I/O input buffer through the I/O interface, the output terminal of I/O input buffer connects the input end of master controller, the output terminal of timing pulse generator connects another input end of master controller, three different output terminals of master controller connect respectively the input end that shows data latches, show the input end of position gating latch and the input end of LED lamp driver, the output terminal that shows data latches all connects integrated nixie display with the output terminal that is connected position gating latch, the output terminal of LED lamp driver connects LED light.
The output terminal of described master controller is connected with communication controller, and this communication controller carries out data communication by communication interface and far end system.
Make integrated circuit board based on the piezoelectric transducer speed detector by 3U industrial standard architectures size with described, can insert in 3U standard industry cabinet.
Described timing pulse generator is for the device of standard clock signal is provided to master controller.
Described master controller is to complete motor vehicle speed is detected for the electric impulse signal of the electric impulse signal according to the first piezoelectric transducer output and the output of the second piezoelectric transducer, and with the device of the real-time output display of test result.
Described demonstration data latches is the device that latchs for the speed data to master controller output.
A described demonstration position gating latch is the device that latchs for bit address corresponding to speed data to master controller output.
Described the first piezoelectric transducer and the second piezoelectric transducer are outer can arrange with identical constant spacing the 3rd piezoelectric transducer.
Adopt the described pick-up unit of motor vehicle speed based on piezoelectric transducer to carry out motor vehicle speed and detect, carry out as follows:
Step 1: successively when being embedded with the first piezoelectric transducer and the second piezoelectric transducer road, the first piezoelectric transducer and the second piezoelectric transducer will be distinguished the output electric pulse signal to master controller when motor vehicle;
Step 2: master controller controls the first piezoelectric transducer by the LED lamp driver and LED lamp state corresponding to the second piezoelectric transducer shows;
Step 3: electric impulse signal reaches the I/O input buffer by the I/O interface and carries out shaping, and the electric impulse signal after shaping inputs to master controller via the I/O port again;
Step 4: the standard time clock pulse signal that master controller provides according to timing pulse generator, piezoelectric transducer after shaping input electric impulse signal is counted timing, this counting timing is converted to motor vehicle again by the first piezoelectric transducer and the second piezoelectric transducer time used;
Step 5: according to motor vehicle by the first piezoelectric transducer and the second piezoelectric transducer time used and the constant spacing between the first piezoelectric transducer and the second piezoelectric transducer, calculate the velocity amplitude of motor vehicle by this constant spacing, and with the motor vehicle speed Conversion of measurement unit, be kilometer/hour;
Step 6: the motor vehicle speed data that will measure reach and show that data latches latchs output, the address of this speed data position correspondence is reached show that position gating latch latchs output simultaneously;
Step 7: the data bit that speed data is corresponding shows on integrated nixie display;
Step 8: master controller can transfer to communication controller with speed data, then through communication interface, reaches far end system, carries out data communication.
the described master controller of step 2 is controlled the LED lamp show state of the correspondence of the first piezoelectric transducer and the second piezoelectric transducer by the LED lamp driver, specifically: when motor vehicle during through the first piezoelectric transducer, the LED display lamp corresponding with this sensor lighted, when motor vehicle sails out of the first piezoelectric transducer, the LED display lamp corresponding with this sensor extinguishes, when motor vehicle during through the second piezoelectric transducer, the LED display lamp corresponding with this sensor lighted, when motor vehicle sails out of the second piezoelectric transducer, the LED display lamp corresponding with this sensor extinguishes.
Beneficial effect:
The piezoelectric transducer that adopts in the utility model, under the effect that is subject to external force, will produce an electric impulse signal,, through Shape correction, form a square-wave pulse.Utilize just this characteristic of piezoelectric transducer, two sensors are embedded on the surface road that spacing is certain distance, when motor vehicle by the time will produce electric impulse signal, utilize the electric impulse signal of these two sensors to carry out timing, draw as calculated the velocity amplitude of detection.
The utility model device is to be intelligent transportation and the evidence-obtaining system of capturing violating the regulations, and a kind of not only economy but also the new departure of motor vehicle speed detection accurately are provided.This device, based on Single-chip Controlling, detects motor vehicle speed in conjunction with piezoelectric transducer.Utilize piezoelectric transducer technology and cheap single-chip microcomputer combination, can be that economy is practical again as toroid winding, and can overcome the shortcoming that toroid winding is not high to the motor vehicle speed accuracy of detection, error is large.Can obtain the velocity amplitude that high precision detects as radar, and than the price economy of Radar Products, material benefit.
This apparatus structure is simple, by 3U industrial standard architectures size, makes integrated circuit board, can insert easily in 3U standard industry cabinet, substitutes former Data mining plate.This device rate accuracy is high, anti-interference is extremely strong.Compare with the capturing system violating the regulations of existing Data mining mode, substantially eliminated the inaccurate phenomenon of original system motor vehicle speed measuring.Greatly improved the motor vehicle speed Detection accuracy.Stop former Data mining system phenomenon large to the motor vehicle speed measuring error, that judge by accident, grab by mistake and again occurred, reduced legal dispute.This detection scheme is simple, practical, economical, is better than existing conventional detection scheme.
Description of drawings
Fig. 1 is the structure of the detecting device of the motor vehicle speed based on the piezoelectric transducer block diagram of the utility model embodiment;
Fig. 2 is the pick-up unit of the motor vehicle speed based on the piezoelectric transducer circuit diagram of the utility model embodiment;
Fig. 3 is the first piezoelectric transducer and the second piezoelectric transducer location arrangements schematic diagram of the utility model embodiment;
Fig. 4 is the first piezoelectric transducer of the utility model embodiment and the second piezoelectric transducer sequential chart that tests the speed;
Fig. 5 is the overhaul flow chart of the motor vehicle speed based on piezoelectric transducer of the utility model embodiment;
Fig. 6 is the location arrangements schematic diagram of the first piezoelectric transducer, the second piezoelectric transducer and the 3rd piezoelectric transducer of the utility model embodiment;
Fig. 7 is the piezoelectric transducer installation site of the utility model embodiment and traditional toroid winding installation site contrast schematic diagram.
Embodiment
Below in conjunction with accompanying drawing, embodiment of the present utility model is elaborated.
As shown in Figure 1, present embodiment is based on the motor vehicle speed pick-up unit of piezoelectric transducer, comprises the first piezoelectric transducer, the second piezoelectric transducer, I/O input buffer, master controller, timing pulse generator, demonstration data latches, shows position gating latch, integrated nixie display, LED lamp driver and LED light;
It is the piezoelectric transducer of the Switzerland Kistler of 9195F511 that the first piezoelectric transducer, the second piezoelectric transducer all adopt model; As shown in Figure 2, I/O input buffer employing model is the six tunnel schmidt trigger reversers of SN74HC14; It is the single-chip microcomputer of AT89C51 that master controller is selected the model of American ATMEL; It is the single-chip microcomputer of AT89C2051 that timing pulse generator is selected the model of American ATMEL; Show that it is the eight road D class triggers with Protection Counter Functions of SN74HC273 that data latches is selected model; Show that it is eight Reuter's bright D class latchs with ternary output of SN74HC373 that position gating latch is selected model; The model that integrated nixie display is selected is SR420401K(or XSM-S5641BB); It is the six tunnel schmidt trigger reversers of SN74HC14 that the LED lamp driver is selected model; LED light is selected diameter
3 red luminotrons.
as shown in Figure 3, the first piezoelectric transducer and the second piezoelectric transducer are embedded in the Vehicle Driving Cycle road of constant spacing S, constant spacing is set as S=2 rice (according to situation, also can set other spacing as 1 meter or 3 meters), the output terminal of the output terminal of the first piezoelectric transducer and the second piezoelectric transducer all is connected to the input end of I/O input buffer through the I/O interface with the piezoelectric transducer signal feed, the output terminal of I/O input buffer connects the input end of master controller, the output terminal of timing pulse generator connects another input end of master controller, three different output terminals of master controller connect respectively the input end that shows data latches, show the input end of position gating latch and the input end of LED lamp driver, the output terminal that shows data latches all connects integrated nixie display with the output terminal that is connected position gating latch, the output terminal of LED lamp driver connects LED light.
Another output terminal of master controller is connected with communication controller, and this communication controller carries out data communication by communication interface and far end system.
Make integrated circuit board based on the piezoelectric transducer speed detector by 3U industrial standard architectures size with described, can insert easily in 3U standard industry cabinet.
Timing pulse generator is for the device of standard clock signal is provided to master controller.
Master controller is to complete motor vehicle speed is detected for the electric impulse signal of the electric impulse signal according to the first piezoelectric transducer output and the output of the second piezoelectric transducer, and with the device of the real-time output display of test result.
Show that data latches is the device that latchs for the speed data to master controller output.
Show that position gating latch is the device that latchs for bit address corresponding to speed data to master controller output.
The first piezoelectric transducer and the second piezoelectric transducer are outer can arrange with identical constant spacing the 3rd piezoelectric transducer.
Adopt the described pick-up unit of motor vehicle speed based on piezoelectric transducer to carry out motor vehicle speed and detect, flow process as shown in Figure 5, is carried out as follows:
Step 1: detected motor vehicle is successively by on the road that is embedded with the first piezoelectric transducer (piezoelectric transducer L1) and the second piezoelectric transducer (piezoelectric transducer L2), and the first piezoelectric transducer and the second piezoelectric transducer difference output electric pulse signal are to master controller;
Step 2: master controller controls the first piezoelectric transducer by the LED lamp driver and LED lamp state corresponding to the second piezoelectric transducer shows;
Specifically: when motor vehicle during through the first piezoelectric transducer, the LED display lamp corresponding with this sensor lighted, when motor vehicle sails out of the first piezoelectric transducer, the LED display lamp corresponding with this sensor extinguishes, when motor vehicle during through the second piezoelectric transducer, the LED display lamp corresponding with this sensor lighted, and when motor vehicle sailed out of the second piezoelectric transducer, the LED display lamp corresponding with this sensor extinguished;
Step 3: electric impulse signal reaches the I/O input buffer by the I/O interface and carries out shaping, and the electric impulse signal after shaping inputs to master controller via the I/O port again;
When the motor vehicle in travelling passes through the first piezoelectric transducer and the second piezoelectric transducer successively, article two, piezoelectric transducer will produce respectively electric impulse signal, and by the piezoelectric transducer signal feed, electric impulse signal is passed to the I/O input buffer via the I/O interface and carry out shaping, then be transferred to master controller I/O port.
Step 4: the standard time clock pulse signal that master controller provides according to timing pulse generator, piezoelectric transducer after shaping input electric impulse signal is counted timing, this counting timing is converted to motor vehicle again by the first piezoelectric transducer and the second piezoelectric transducer time T used;
Step 5: according to motor vehicle by the first piezoelectric transducer and the second piezoelectric transducer time used and the constant spacing S between the first piezoelectric transducer and the second piezoelectric transducer, calculate the velocity amplitude V=S/T of motor vehicle by this constant spacing, and with the motor vehicle speed Conversion of measurement unit, be kilometer/hour;
The first piezoelectric transducer and the second piezoelectric transducer test the speed sequential chart as shown in Figure 4, and wherein, t1 is the time of motor vehicle through the first piezoelectric transducer, and t2 is the time of motor vehicle through the second piezoelectric transducer, T=t2-t1.
Step 6: the motor vehicle speed data that will measure reach and show that data latches latchs output, the address of this speed data position correspondence is reached show that position gating latch latchs output simultaneously;
Step 7: the data bit that speed data is corresponding shows on integrated nixie display;
Step 8: master controller can transfer to communication controller with speed data, then through communication interface, reaches far end system, carries out data communication.
More accurate for the speed that makes tested vehicle, another embodiment of the present utility model is, will be based on the motor vehicle speed pick-up unit of two piezoelectric transducers, then increase a piezoelectric transducer and expand to three piezoelectric transducer speed and detect.Every two piezoelectric transducers combination in three piezoelectric transducers, can calculate respectively three motor vehicle speed values, and the mode of every kind of combination is L1 and L2, L1 and L3, L2 and L3 combination, as shown in Figure 6.Can obtain three velocity amplitude V1(L1 and L2 array mode in present embodiment), V2(L1 and L3 array mode) and V3 (L2 and L3 array mode), utilize method of weighted mean to obtain average velocity
The formula of mean value is:
=(V1+V2+V3)/3, wherein V1, V2, V3 are three velocity amplitudes that obtain,
For the final motor vehicle average velocity that obtains.Relative error range between velocity amplitude V1, V2 and V3 velocity amplitude less than 3% time is effective value.
Claims (4)
1. the pick-up unit of the motor vehicle speed based on piezoelectric transducer, is characterized in that: comprise the first piezoelectric transducer, the second piezoelectric transducer, I/O input buffer, master controller, timing pulse generator, demonstration data latches, show position gating latch, integrated nixie display, LED lamp driver, LED light;
the first piezoelectric transducer and the second piezoelectric transducer are embedded in the motor-driven vehicle going road of constant spacing, the output terminal of the output terminal of the first piezoelectric transducer and the second piezoelectric transducer all is connected to the input end of I/O input buffer through the I/O interface, the output terminal of I/O input buffer connects the input end of master controller, the output terminal of timing pulse generator connects another input end of master controller, three different output terminals of master controller connect respectively the input end that shows data latches, show the input end of position gating latch and the input end of LED lamp driver, the output terminal that shows data latches all connects integrated nixie display with the output terminal that is connected position gating latch, the output terminal of LED lamp driver connects LED light.
2. the pick-up unit of the motor vehicle speed based on piezoelectric transducer according to claim 1, it is characterized in that: the output terminal of described master controller is connected with communication controller, and this communication controller carries out data communication by communication interface and far end system.
3. the pick-up unit of the motor vehicle speed based on piezoelectric transducer according to claim 1, it is characterized in that: make integrated circuit board based on the piezoelectric transducer speed detector by 3U industrial standard architectures size with described, can insert in 3U standard industry cabinet.
4. the pick-up unit of the motor vehicle speed based on piezoelectric transducer according to claim 1, is characterized in that: outside described the first piezoelectric transducer and the second piezoelectric transducer, the 3rd piezoelectric transducer can be set with identical constant spacing.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103308710A (en) * | 2013-06-03 | 2013-09-18 | 沈阳天久信息技术工程有限公司 | Motor vehicle speed detection device and method based on piezoelectric transducers |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103308710A (en) * | 2013-06-03 | 2013-09-18 | 沈阳天久信息技术工程有限公司 | Motor vehicle speed detection device and method based on piezoelectric transducers |
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