CN206312366U - High accuracy road traffic volume detection device - Google Patents

High accuracy road traffic volume detection device Download PDF

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Publication number
CN206312366U
CN206312366U CN201621373919.6U CN201621373919U CN206312366U CN 206312366 U CN206312366 U CN 206312366U CN 201621373919 U CN201621373919 U CN 201621373919U CN 206312366 U CN206312366 U CN 206312366U
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CN
China
Prior art keywords
detection device
high accuracy
traffic volume
hmc1022
road traffic
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Expired - Fee Related
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CN201621373919.6U
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Chinese (zh)
Inventor
肖宝森
康恺
纪艺娟
吴家浩
曾育川
黄炳宏
李智飞
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Xiamen University Tan Kah Kee College
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Xiamen University Tan Kah Kee College
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Priority to CN201621373919.6U priority Critical patent/CN206312366U/en
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Abstract

The utility model is related to a kind of high accuracy road traffic volume detection device.Signal amplification module, the Zigbee wireless communication modules for realizing being communicated with host computer being connected including main control module and with the main control module, the signal amplification module are connected and installed on the track of road surface and for detecting whether have the magnetoresistive transducer HMC1022 that vehicle passes through;Also include a power management module for being used to be powered for whole device.The utility model device has high measurement accuracy, low-power consumption, while circuit structure is simple, it is easy to accomplish.

Description

High accuracy road traffic volume detection device
Technical field
The utility model is related to a kind of high accuracy road traffic volume detection device, it is adaptable to the vehicle/wagon flow of various occasions Amount detection.
Background technology
At present, vehicle testing techniques common both at home and abroad mainly have:Radar(Microwave), laser, the mode such as video.In recent years Come, in Bus- Speed Monitoring, magnetic resistance tests the speed and more paid attention to for magnetoresistive transducer more popularization and application.Now these three modes are introduced respectively It is as follows:
1. radar detection technique
The principle of radar velocity measurement is using microwave Doppler effect.When object is static, the frequency of radar transmitting wave with it is anti- The frequency of ejected wave is consistent;When object is moved, two wave frequency rate ,s are different, i.e., can produce frequency displacement.Radar meter is exactly according to calculating The size of the back wave frequency shift amount for receiving, and then draw the speed of related movement of testee.Radar detection technique mainly should For testing the speed for fastlink.
2. laser measuring technology
Laser measuring technology, by the laser homed on its target that the light velocity is c, produces a back wave using the excellent specific property of laser, By calculate receive back wave time and transmitting laser time both between time difference, can try to achieve measured target with The distance between Laser emission position.
3. video detection technology
Video detection can in real time show traffic information by display, and it is mainly used in traffic intersection or prosperity Crossing.Video detection is widely used in traffic, building house etc..The workflow of video detection approximately as:Use high-definition camera Machine capture traffic intersection road conditions image, then by a series for the treatment of such as image procossing, target identification after, calculate car speed.
Prior art shortcoming:
1. for radar detection technique:
(1)The wave beam of radar emission is not comprehensive, but has certain subtended angle scope, and intensity is come not as laser Concentrate, therefore effectively test the speed distance not as laser velocimeter comes far;
(2)The certainty of measurement of radar meter is influenceed by the subtended angle size of launching beam, and subtended angle is bigger, unit cambered surface intensity It is lower, the accuracy rate that tests the speed more susceptible;Conversely, then influenceing smaller.It is, in general, that when over-speed vehicles are surmounting normal enforcement During vehicle, it is which car hypervelocity that radar meter is difficult judgement;
(3)Accuracy of detection cannot ensure that vehicle, overall height and the unimpeded degree of road traffic can all influence accuracy of detection.
2. for laser measuring technology
(1)Laser velocimeter has its limitation, from above-mentioned it is known that the necessary perpendicular alignmnet measured target of laser beam, no The laser beam intensity for then reflecting is not enough, it is impossible to detect reflected signal.Additionally, when tested vehicle is distant and is in Mobile status, will all largely effect on Detection accuracy;
(2)It is the accuracy that guarantee is tested the speed, laser velocimeter device works under can be only in inactive state, is such as used for highway Administer hypervelocity phenomenon, it is easy to found by driver, will so fallen flat;
(3)Costly, current most laser velocimeter depends on import to price, and domestic product quality is not also up to To the level of American-European countries.
3. for video detection technology
(1)It is mobile inconvenient, it is unfavorable for being tested the speed at random in any section;
(2)The technology be affected by the external environment it is very big, when the relatively low weather of the visibilitys such as mist, many sand and dust is had, inspection Surveying precision will become very low.
It can be seen that, all there is certain defect in current various detection modes.Because vehicle all contains ferromagnetic material material, When vehicle is by magnetoresistive transducer, disturbance can be produced to the earth's magnetic field on periphery, by the variable quantity of real-time capture earth magnetism, can be with Judge whether magnetoresistive transducer top has vehicle to pass through.The application motion technical problem to be solved:Vehicle Flow Detection precision, no Influenceed by ambient weather, stable and reliable in work and cost.
The content of the invention
The purpose of this utility model is to provide a kind of high accuracy road traffic volume detection device, and the device has high detection Precision, low-power consumption, while circuit structure is simple, it is easy to accomplish.
To achieve the above object, the technical solution of the utility model is:A kind of high accuracy road traffic volume detection device, bag Include main control module and be connected with the main control module signal amplification module, for realize the Zigbee that is communicated with host computer without Line communication module, the signal amplification module is connected and installed on the track of road surface and for detecting whether has the magnetic that vehicle passes through Resistance sensor HMC1022;Also include a power management module for being used to be powered for whole device.
In the embodiment of the utility model one, also including be connected with the main control module reset circuit, crystal oscillating circuit, LCD1602 display modules.
In the embodiment of the utility model one, the main control module uses CC2530 chips, and it carries 14 A/D conversions Function.
In the embodiment of the utility model one, the signal amplification module uses AD620 chips, to amplify magnetoresistive transducer Detected small voltage signal.
In the embodiment of the utility model one, the magnetoresistive transducer is also associated with a set/reset circuit.
In the embodiment of the utility model one, the external+5V power supplys of HMC1022 chips, and the ceramics electricity for passing through 0.1 μ f Road filters radio-frequency component with the voltage stablized, the S/R+ of HMC1022 chips(A)Pin is connected to described through one 0.1 μ f electric capacity The D1 pins of the cmos switch pipe IRF7105 of set/reset circuit, the S/R- of HMC1022 chips(A)Pin is grounded, HMC1022 OUT+ (A), the OUT- (A) of chip the first differential input ends respectively with signal amplification module, the second differential input end connect.
In the embodiment of the utility model one, the power management module includes that 5V direct current regulation circuits and 2.5V direct currents are steady Volt circuit.
Compared to prior art, the utility model has the advantages that:
1st, the vehicle flow detection system of the present apparatus detects information of vehicle flowrate on road by using HMC1022 sensors, can be with Improve accuracy of detection;
2nd, vehicle Flow Detection sensor uses magnetoresistive transducer HMC1022, with HMC1001/1002, three axle magnetoresistive transducers Compare, HMC1022 has more low-power consumption, while reduce peripheral circuit, node ceiling capacity mainly consume wireless transmission with Receive the data moment;
3rd, detection means(Comprising magnetoresistive transducer HMC1022)Be placed under road surface, can avoid the visibilitys such as mist, many sand and dust compared with Low adverse weather conditions accuracy of detection;
4th, detection means circuit structure is simple, installs very flexibly, how much can increase or decrease detection according to road track Point quantity;
5th, it is networking flexibility, good confidentiality, low complex degree, low-power consumption, low cost, low using ZigBee wireless communication modules Message transmission rate, and can avoid transmitting data using wired mode, it is convenient to install;
6th, signal amplification module uses high precision, low in energy consumption, wide input voltage range, and the good difference of gain performance to put Big device AD620.
Brief description of the drawings
Fig. 1 is the utility model hardware block diagram.
Fig. 2 is the utility model HMC1022 pinouts.
Fig. 3 is the circuit theory diagrams of the utility model magnetoresistive transducer HMC1022.
Fig. 4 is the utility model vehicle flowrate signal flow path switch figure.
Fig. 5 is the utility model IRF7105 internal structures and pin figure.
Fig. 6 is the utility model set/reset timing circuit figure.
The voltage change curve that sensor is detected when Fig. 7 is the utility model vehicle by directly over sensor test point Figure.
Fig. 8 is the utility model 5V direct current regulation circuit schematic diagrams.
Fig. 9 is the utility model 2.5V direct current regulation circuit schematic diagrams.
Figure 10 is the utility model AD620 amplifying circuit schematic diagrams.
Specific embodiment
Below in conjunction with the accompanying drawings, the technical solution of the utility model is specifically described.
A kind of high accuracy road traffic volume detection device of the present utility model, including main control module and with the master control molding The signal amplification module of block connection, the Zigbee wireless communication modules for realizing being communicated with host computer, the signal amplify mould Block is connected and installed on the track of road surface and for detecting whether has the magnetoresistive transducer HMC1022 that vehicle passes through;Also include one For the power management module powered for whole device.Also include the reset circuit, the crystal oscillator electricity that are connected with the main control module Road, LCD1602 display modules.
The main control module uses CC2530 chips, and it carries 14 A/D translation functions.The signal amplification module is adopted AD620 chips are used, to amplify the small voltage signal detected by magnetoresistive transducer.
The magnetoresistive transducer is also associated with a set/reset circuit.External+5V the power supplys of HMC1022 chips, and lead to Cross the voltage that the ceramics circuit of 0.1 μ f filters radio-frequency component to be stablized, the S/R+ of HMC1022 chips(A)Pin is through 1 μ f electric capacity is connected to the D1 pins of the cmos switch pipe IRF7105 of the set/reset circuit, the S/R- of HMC1022 chips(A)Draw Pin is grounded, OUT+ (A), the OUT- (A) of HMC1022 chips the first differential input end respectively with signal amplification module, second poor Input is divided to connect.
The power management module includes 5V direct current regulation circuits and 2.5V direct current regulation circuits.
It is below specific embodiment of the utility model.
High accuracy road traffic volume detection device of the present utility model, mainly includes signal amplification module, A/D moduluss of conversion Block, sensor set/reset module, magnetoresistive transducer HMC1022, ZigBee wireless communication module, magnetoresistive transducer HMC1022 It is placed in the road surface of road track.
Fig. 1 show the hardware system block diagram of road traffic detecting system.When vehicle is by being installed on the track of road surface Magnetoresistive transducer near when magnetic field size change, sensor can accurately detect the change of magnetic field signal, and by magnetic Field signal is changed into voltage signal.System includes the signal amplification module, using AD620 chips, for amplifying magneto-resistive transducing Small and weak voltage signal detected by device HMC1022;Comprising the A/D modular converters, by the voltage signal conversion after amplification For ease of the data signal of analysis;Comprising the ZigBee wireless communication modules, the information of vehicle flowrate for that will detect sends To host computer.
Fig. 2 show HMC1022 pinouts, HMC1022 not only have magnetic field intensity scope wider and relatively low set/ Resetting current performance, and with accuracy of detection is high, stable work in work, small size, anti-electromagnetic noise, to nonferromagnetic object Reactionless the features such as.Wheatstone bridge is the core component of HMC1022, there is a sensitive axes in electric bridge, is respectively intended to survey Amount magnetic field Bx parallel with chip and vertical direction and.In linear scope, the change of magnetic resistance causes the change of output voltage Change, directly represent the intensity in magnetic field.
Fig. 3 show the circuit of magnetoresistive transducer HMC1022.External+5V power supplys, and the ceramic disc capacitor filter for passing through 0.1uf Voltage except radio-frequency component to be stablized.Because application scenario is complicated and changeable, and the utility model is to detect vehicle to the earth The influence in magnetic field changes to judge information of vehicles, therefore without using bias current circuit, respective pins are hanging.S/R+ (A) pin meets set, the output end D1 of the switch mosfet pipe IRF7105 of reset circuit.Due to each set/reset pulse only Apply in one direction, if that is, the pulse of+4A is used to set sensor, impulse attenuation electric current is not lower than 0 electric current. Any negative current(Or less than rated current)Pulse signal can all cause sensor cannot set, thus cannot obtain optimal Sensitivity.And the level of set/reset pulse that utility model is produced is not less than 0, so by S/R-(A)Pin is grounded so that Set/reset pulse current can flow directly into ground terminal by S/R+ ends, it is ensured that its flow direction is consistent.And the differential signal of sensor is defeated Go out differential input end+IN and-the IN end of pin OUT+ (A) and OUT- (A) respectively with signal amplification chip AD620 to connect.
Fig. 4 show vehicle flowrate signal flow path switch figure, and periphery magnetic field can be caused when vehicle is by sensor detection node Change, the magnetic simulation signal that magnetoresistive transducer HMC1022 will be detected is sent in A/D modular converters by I/O interfaces, will Analog signal is converted to data signal, and the data signal after conversion is sent into each base station by radio circuit.
Fig. 5 show IRF7105 internal structures and pin figure, is realized by one group of ferromagnetism resistance inside HMC1022 Set/reset, from cmos switch pipe IRF7105, its conducting and cut-off is controlled by clock signal, and set/multiple is produced with this Digit pulse.
Fig. 6 show set/reset timing circuit figure, and the pulse current that utility model has 2us pulsewidths per 50ms produces electricity Road, also further can reduce frequency to save power consumption.Switch switching tube IRF7105's by the low level clock signal of 2us pulsewidths Conducting and cut-off, control set/reset pulse.Set pulse is formed by the tantalum electric capacity of a 1uF, while connecting one on power supply The dropping resistor of individual 200 Ω, to reduce noise.The output end of IRF7105 is connected to HMC1022's by the electric capacity of a 0.1uF S/R+ ends.
The voltage change curve that sensor is detected when Fig. 7 show automobile by directly over sensor test point, detection Value jumps to 2.6V or so from 1V jumps.
Fig. 8,9 show 5V, 2.5V direct current regulation circuit.System power supply uses external 9V button cells or 7.2V lithium batteries Or 9V voltages are exported by power regulator.Because this DC voltage is that possible contain larger ripple, can be to the stability of system Produce large effect, it is necessary to given by reliable filter circuit and filtered, make ripple components in output voltage as much as possible Reduce, so as to obtain smooth, galvanic current pressure.But the magnitude of voltage of 9V and 7.2V can not be supplied directly to the system module of 5V After electricity, therefore filter circuit, in addition it is also necessary to connect mu balanced circuit.
The effect of mu balanced circuit is, when cell voltage changes, to maintain output DC voltage stability constant.Cell voltage is defeated After going out, by passing through electrochemical capacitor after commutation diode again(100μF)One-level filtering is carried out, it is miscellaneous inside direct current to remove Ripple, prevents interference.Filtered direct current turns into the 5V power supplys of stabilization by three terminal regulator AMS1117-5.0 voltage stabilizings again, its The Vin pin of middle AMS1117-5.0 are input pins, connect battery DC positive source, and GND is grounding leg, connect battery DC power supply and bear Pole, Vout is output pin, and it is exactly+5V with the voltage of grounding leg.5V power supplys out again by the secondary filter of electrochemical capacitor, Make 5V power supplys more reliable and more stable.A resistance and a red light emitting diodes of 1K are added in 5V voltage-stabilized power supplies simultaneously, when After upper electricity, red light emitting diodes are lighted, and represent that power work is normal.Now the power supply of a stabilization output 5V has been designed It is good, as shown in Figure 8.Because amplifier module is worked using single supply powering mode, in order to reach preferably detection amplification effect, A reference voltage Vref need to be provided to amplifier, the utility model may be programmed shunt regulator diode TL431A very with three ends Easily just can produce+2.5V a reference voltage for stabilization.The 5V power supplys that AMS1117-5.0 is exported are by an electricity of 10K Resistance is connected on the negative electrode of TL431A, and by its negative electrode and reference edge short circuit, plus earth, such negative electrode or reference edge and grounding leg Voltage is exactly+2.5V, recycles the ceramic disc capacitor of 0.1uf to filter radio-frequency component, just can obtain+2.5V the voltages of a stabilization , as shown in Figure 9.For the utility model of this power module, it is fully able to meet power supply needed for single-chip microcomputer and integrated package It is required that.
Figure 10 show AD620 amplifying circuits.Magnetoresistive transducer HMC1022 is that magnetic field signal is converted into differential voltage is defeated Go out, be OUT+ for X-axis output voltage virtual value Vo (A)(A)And the difference between OUT- (A), due to A/D converters in piece Input voltage range be 0-5V.In order to effectively using the sampling precision of A/D converter, improve detection accuracy, A/ is being carried out Before D samplings, the weak voltage signals that magnetoresistive transducer is exported need to be amplified.The utility model selects instrument amplifier AD620.Its+IN is set to correspond respectively to the Differential Input OUT+ of sensor with-IN signal input parts(A)With OUT- (A).
The input of AD620 differential amplifier circuits is the difference output of magnetoresistive transducer, output end voltage value and two inputs Between difference magnitude of voltage it is linear, its relational expression as shown in Equation 1, in formula:Be gain multiplication factor, its withPass It is formula as shown in Equation 2,Unit be.From gain multiplication factor expression formula 2-2, the multiplication factor of amplifying circuit is only By resistanceInfluence, therefore adjustmentResistance just adjustable circuit multiplication factor.Signal is amplified in utility model The value that 500 times, i.e. adjustment precision slide resistance RP1 is 98.6
The present embodiment uses HMC1022 to gather sensor for information of vehicle flowrate with CC2530 as main control module, uses AD620 is difference amplifier, and the vehicle flowrate signal to collecting is amplified treatment;Changed using 14 A/D in CC2530, Convert analog signals into data signal;Using cmos switch pipe IRF7105, and its conducting and cut-off are controlled by clock signal, Set/reset pulse is produced with this;Information of vehicle flowrate is sent to by host computer using ZigBee wireless communication modules, such as handing over Siphunculus reason information departments consult, to understand road traffic condition.
The gain factor G of signal amplification module is adjusted, it is 500 that the system sets G, according to related gain formula, regulation essence Close sliding resistance makes RG be 98.6 ohm.
When above the frequent magnetoresistive transducer of vehicle, magnetic field changes, and changes of magnetic field is converted to voltage change, and voltage becomes Change very faint and of short duration, it is desirable to which sample frequency is high, the 14A/D conversions in the CC2530 of selection can meet requirement.For A/D Modular converter is, it is necessary to write and debug A/D conversion programs.
Utility model has the pulse current of 2us pulsewidths to produce circuit per 50ms, further reduces frequency to save power consumption.By The conducting and cut-off of the low level clock signal switching switching tube IRF7105 of 2us pulsewidths, control set/reset pulse.Set arteries and veins Punching is formed by the tantalum electric capacity of a 1uF, while a dropping resistor of 200 Ω of being connected on power supply, to reduce noise. The output end of IRF7105 is connected to the S/R+ ends of HMC1022 by the electric capacity of a 0.1uF.
The utility model product is placed in into scene carries out experiment test, when magnetoresistive transducer detection node A is placed in road Centre, when vehicle passes through from directly over detection node, detected value jumps to 2.6V or so from 1V jumps, and detection value changes are quite notable, from Fig. 7 can be clearly seen.When sensor node test has obtained 100 cars, and actual is 98 by vehicle, Detection accuracy It is 98%.It was verified that the Detection accuracy of the method is high.Crossroad traffic lights control is such as applied to, friendship can be greatly improved Way system efficiency.
The above, only the utility model preferably specific embodiment, but protection domain of the present utility model is not This is confined to, any one skilled in the art can readily occur in the technical scope that the utility model is disclosed Change or replacement, should all cover within protection domain of the present utility model.Therefore protection domain of the present utility model should It is defined by scope of the claims.

Claims (7)

1. a kind of high accuracy road traffic volume detection device, it is characterised in that:Including main control module and with the main control module The signal amplification module of connection, the Zigbee wireless communication modules for realizing being communicated with host computer, the signal amplification module It is connected and installed on the track of road surface and for detecting whether has the magnetoresistive transducer HMC1022 that vehicle passes through;Also include that one uses In the power management module powered for whole device.
2. high accuracy road traffic volume detection device according to claim 1, it is characterised in that:Also include and the master control Reset circuit, crystal oscillating circuit, the LCD1602 display modules of molding block connection.
3. high accuracy road traffic volume detection device according to claim 1, it is characterised in that:The main control module is adopted CC2530 chips are used, it carries 14 A/D translation functions.
4. high accuracy road traffic volume detection device according to claim 1, it is characterised in that:The signal amplification module Using AD620 chips, to amplify the small voltage signal detected by magnetoresistive transducer.
5. high accuracy road traffic volume detection device according to claim 1, it is characterised in that:The magnetoresistive transducer is also It is connected with a set/reset circuit.
6. high accuracy road traffic volume detection device according to claim 5, it is characterised in that:The HMC1022 chips External+5V power supplys, and the voltage that radio-frequency component is filtered to be stablized by the ceramics circuit of 0.1 μ f, the S/ of HMC1022 chips R+(A)Pin is connected to the D1 pins of the cmos switch pipe IRF7105 of the set/reset circuit through one 0.1 μ f electric capacity, The S/R- of HMC1022 chips(A)Pin is grounded, OUT+ (A), the OUT- (A) of HMC1022 chips respectively with signal amplification module First differential input end, the second differential input end connect.
7. high accuracy road traffic volume detection device according to claim 1, it is characterised in that:The power management module Including 5V direct current regulation circuits and 2.5V direct current regulation circuits.
CN201621373919.6U 2016-12-15 2016-12-15 High accuracy road traffic volume detection device Expired - Fee Related CN206312366U (en)

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CN201621373919.6U CN206312366U (en) 2016-12-15 2016-12-15 High accuracy road traffic volume detection device

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Application Number Priority Date Filing Date Title
CN201621373919.6U CN206312366U (en) 2016-12-15 2016-12-15 High accuracy road traffic volume detection device

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109118784A (en) * 2018-10-24 2019-01-01 广东工业大学 A kind of magnetic resistance vehicle detecting sensor and intelligent traffic control system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109118784A (en) * 2018-10-24 2019-01-01 广东工业大学 A kind of magnetic resistance vehicle detecting sensor and intelligent traffic control system

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Granted publication date: 20170707

Termination date: 20191215