CN202748940U - Infrared sensor-based vehicle-flowrate detection apparatus - Google Patents
Infrared sensor-based vehicle-flowrate detection apparatus Download PDFInfo
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- CN202748940U CN202748940U CN 201220415233 CN201220415233U CN202748940U CN 202748940 U CN202748940 U CN 202748940U CN 201220415233 CN201220415233 CN 201220415233 CN 201220415233 U CN201220415233 U CN 201220415233U CN 202748940 U CN202748940 U CN 202748940U
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Abstract
The utility model discloses an infrared sensor-based vehicle-flowrate detection apparatus, comprising two pyroelectric infrared sensors which are separated for a certain distance and are arranged on or beside a road, a single-chip microcomputer and a display. The two pyroelectric infrared sensors are used for respectively outputting a pulse signal to the single-chip microcomputer when detecting the vehicle to put in. The single-chip microcomputer is used for calculating vehicle passing number based on the pulse signal, time the vehicle passes by the two pyroelectric infrared sensors, the distance of the two pyroelectric infrared sensors and vehicle speed based on the time and the distance and sending to the display for displaying. Compared with conventional detection methods, the vehicle-flowrate detection apparatus provided by the utility model is simple and accurate in detection and has an important reality meaning on traffic management.
Description
Technical field
The utility model relates to vehicle flowrate and speed of a motor vehicle detection technique field.
Background technology
In city management and safeguarding, the management of traffic route is particularly important with construction, reasonably arranges road both can guarantee people's routine work needs of life, can guarantee that again Community health develops in an orderly manner, reaches the effect of getting twice the result with half the effort.The detection of vehicle flowrate and the speed of a motor vehicle is the foundation of intelligent traffic administration system, it is the important indicator of analyzing road conditions, in system, occupy critical role, can be the assessment road congestion conditions, detailed data are provided, all have great significance for judging and avoid the road congestion situation, monitoring timely and accurately for relieving traffic congestion, formulate the road reformation scheme.
Traffic flow detection system is exactly a kind of vehicle flowrate to be added up and the system that records, utilize it can realize to road traffic effectively and rational control and management.At present, the method and system that the relevant magnitude of traffic flow detects are a lot, but all exist operation calculation method complicated, or the problem of assay device structures complexity, are unfavorable for popularizing, promoting.
The utility model content
Technical problem to be solved in the utility model provides a kind of simple to operate, and accuracy rate is high utilizes pyroelectric infrared sensor to measure traffic flow detecting device based on infrared sensor.
The utility model is such:
A kind of traffic flow detecting device based on infrared sensor comprises that two are separated by a distance pyroelectric infrared sensor, a single-chip microcomputer and a display that is installed on road top or side; Export respectively a pulse signal when described two pyroelectric infrared sensors are used for detecting vehicle and sail into and send into described single-chip microcomputer; Described single-chip microcomputer is used for calculating vehicle according to described pulse signal and calculates the speed of a motor vehicle by number and calculating and according to vehicle by the time of described two pyroelectric infrared sensors, the distance of described two pyroelectric infrared sensors, and sends into described display and show.
Described traffic flow detecting device based on infrared sensor comprises a signal processor, is used for the pulse signal of described pyroelectric infrared sensor output is carried out every straight amplification, compares the described single-chip microcomputer of the rear input of Screening Treatment reason.
Described signal processor includes:
Every straight amplifying circuit, be used for the pulse signal of described pyroelectric infrared sensor output is carried out exporting to the comparison module circuit after straight amplification;
The comparison module circuit is used for described pulse signal every straight amplification and threshold voltage are compared, but inputs to described single-chip microcomputer after filtering out described single-chip microcomputer processing signals.
Described comparison module circuit comprises window comparator circuit and a digital regulation resistance, and described digital regulation resistance is used for the threshold voltage of using when described window comparator circuit comparison Screening Treatment signal is adjusted in control by described Single-chip Controlling.
Described display is LCD display.
The utility model by the information of vehicles output pulse signal that utilizes two pyroelectric infrared sensor collections of separating certain distance and pass through to single-chip microcomputer, calculating vehicle by single-chip microcomputer according to described pulse signal calculates vehicle speed by the time and delivers to the display demonstration by number and according to the distance between described sensor and vehicle, thereby finish the measurement to wagon flow quantitative statistics and the speed of a motor vehicle, realized that real-time demonstration detects and demonstration vehicle flowrate and the speed of a motor vehicle; Simultaneously, the utility model method is simple, detects accurately.
Description of drawings
Fig. 1 uses the utility model based on the schematic diagram of the traffic flow detecting device of infrared sensor;
Fig. 2 is the structure principle chart based on the traffic flow detecting device of infrared sensor that the utility model embodiment provides;
Fig. 3 is the circuit theory diagrams of the pyroelectric infrared sensor that provides of the utility model embodiment;
The processing flow chart of the pyroelectric infrared sensor output signal that Fig. 4 the utility model embodiment provides;
Fig. 5 is the circuit theory diagrams every straight amplifying circuit that the utility model embodiment provides;
Fig. 6 is the circuit theory diagrams of the digital regulation resistance that provides of the utility model embodiment;
Fig. 7 is the circuit theory diagrams of the window comparator circuit that provides of the utility model embodiment;
Fig. 8 is the display circuit schematic diagram of the display that provides of the utility model embodiment;
Fig. 9 is the schematic diagram of the display interface of the display that provides of the utility model embodiment;
The circuit theory diagrams of the single-chip microcomputer storer that Figure 10 the utility model embodiment provides;
Figure 11 is the process flow diagram of single-chip microcomputer external interrupt INT 1 control program that provides of the utility model embodiment
Figure 12 is the process flow diagram of single-chip microcomputer external interrupt INT 0 control program that provides of the utility model embodiment;
Figure 13 is the process flow diagram of the single-chip microcomputer inquiry control program that provides of the utility model embodiment;
Figure 14 is the process flow diagram of the regulating system detection sensitivity that provides of the utility model embodiment.
Embodiment
Below in conjunction with drawings and Examples the utility model is further specified.
The utility model by the information of vehicles output pulse signal that utilizes two pyroelectric infrared sensor collections of separating certain distance and pass through to single-chip microcomputer, calculating vehicle by single-chip microcomputer according to described pulse signal calculates vehicle speed by the time and delivers to the display demonstration by number and according to the distance between described sensor and vehicle, thereby finish the measurement to wagon flow quantitative statistics and the speed of a motor vehicle, realized that real-time demonstration detects and demonstration vehicle flowrate and the speed of a motor vehicle.
Use the utility model based on the detection method of the traffic flow detecting device of infrared sensor, may further comprise the steps:
Two pyroelectric infrared sensors that are connected with a single-chip microcomputer are separated by a distance along the link length direction are installed on road top or side, and described two pyroelectric infrared sensors are in the same plane;
Output pulse signal was to described single-chip microcomputer when the first pyroelectric infrared sensor detected a vehicle and sails into, and the single-chip microcomputer built-in timer begins timing, and described single-chip microcomputer adds 1 to the counting of vehicle flowrate simultaneously;
Output pulse signal was to described single-chip microcomputer when the second pyroelectric infrared sensor detected above-mentioned vehicle and sails into, described timer stops timing, behind the described vehicle speed of Time Calculation that is calculated according to the distance between described two pyroelectric infrared sensors and described timer by described single-chip microcomputer, will count and the speed of a motor vehicle is delivered to described display demonstration.
Before behind the pulse signal of described pyroelectric infrared sensor output, sending into described single-chip microcomputer, further comprising the steps of:
Described pulse signal is carried out step every straight amplification, comparison Screening Treatment.
Among the utility model embodiment, the external storer of establishing of described single-chip microcomputer.
When described the second pyroelectric infrared sensor did not detect above-mentioned vehicle and sails into, the counting of described single-chip microcomputer turned back to original state.
The purpose of this utility model also is to provide a kind of traffic flow detecting device based on infrared sensor, comprises that two are separated by a distance pyroelectric infrared sensor, a single-chip microcomputer and a display that is installed on road top or side; Export respectively a pulse signal when described two pyroelectric infrared sensors are used for detecting vehicle and sail into and send into described single-chip microcomputer; Described single-chip microcomputer is used for calculating vehicle according to described pulse signal and calculates the speed of a motor vehicle by number and calculating and according to vehicle by the time of described two pyroelectric infrared sensors, the distance of described two pyroelectric infrared sensors, and sends into described display and show.
Described traffic flow detecting device based on infrared sensor comprises a signal processor, is used for the pulse signal of described pyroelectric infrared sensor output is carried out every straight amplification, compares the described single-chip microcomputer of the rear input of Screening Treatment reason.
Described signal processor includes:
Every straight amplifying circuit, be used for the pulse signal of described pyroelectric infrared sensor output is carried out exporting to the comparison module circuit after straight amplification;
The comparison module circuit is used for described pulse signal every straight amplification and threshold voltage are compared, but inputs to described single-chip microcomputer after filtering out described single-chip microcomputer processing signals.
Described comparison module circuit comprises window comparator circuit and a digital regulation resistance, and described digital regulation resistance is used for the threshold voltage of using when described window comparator circuit comparison Screening Treatment signal is adjusted in control by described Single-chip Controlling.
Described display is LCD display.
Referring to shown in Figure 1, the figure shows the traffic flow detecting device based on infrared sensor that the utility model embodiment provides.With two pyroelectric infrared sensors 1,2 in the same plane, and be separated by a distance and be installed on suitably height and position of road top, when having vehicle to pass through, produce an alternation infrared radiation signal on the sensor, make sensor circuit produce a faint voltage signal, this signal is sent to amplification and rectification circuit, and output pulse signal is sent into single-chip microcomputer after amplifying shaping, by single-chip microcomputer count and and timing, and show that by display vehicle is by number and the speed of a motor vehicle.
Mainly use the functions such as the interruption of single-chip microcomputer and counting for the detection of vehicle flowrate, measure the mistiming that two pyroelectric infrared sensors detect for interruption, timer that single-chip microcomputer is mainly used in the detection of the speed of a motor vehicle, calculate the speed of a motor vehicle according to the actual range of two pyroelectric infrared sensors.
Described two pyroelectric infrared sensors also can separate certain distance and be installed on the road side location.Can be to install by support, or utilize overline bridge to install, can be installed on the Width both sides of overline bridge, or be installed on the same side.
Shown in Fig. 1 ~ 2, the structure based on the traffic flow detecting device of infrared sensor that the figure shows that the utility model embodiment provides for convenience of explanation, only shows the part relevant with the utility model embodiment.
In the present embodiment, described two pyroelectric infrared sensors place respectively the overline bridge two ends, and what establish that automobile touches first is pyroelectric infrared sensor 1, after touch and be pyroelectric infrared sensor 2.
Because automobile has high-temperature part, such as engine, water tank etc., so when the automobile in moving crossed under two pyroelectric infrared sensors, pyroelectric infrared sensor 1 can at first detect and collect signal, and produces corresponding waveform; Then signal is amplified under distortionless prerequisite, and be converted into voltage signal, again according to the threshold voltage that sets, the signal that gathers after amplifying is screened, be initially high level, if the signal after the screening is higher than the threshold voltage value and then produces low level, then keep high level if be lower than the threshold voltage value, when arriving, counts negative edge.
Under the original state, only allow pyroelectric infrared sensor 1 open, if when detecting negative edge, pyroelectric infrared sensor 1 is closed at once, and pyroelectric infrared sensor 2 is opened simultaneously, if pyroelectric infrared sensor 2 detects negative edge within a certain period of time, then thinking has vehicle to cross, and counts vehicle flowrate; Meanwhile, single-chip microcomputer records the mistiming that two pyroelectric infrared sensors detect negative edge, and according to the mistiming calculating speed of a motor vehicle.
If pyroelectric infrared sensor 2 does not detect negative edge within a certain period of time, then can be regarded as once and disturb, and system comes back to original state.
In signal acquisition process, pyroelectric infrared sensor is placed directly over the overline bridge, point to the road of Vehicle Driving Cycle, detect information of vehicles and the faint electric signal of conversion output, other disturb through elimination behind straight amplifying circuit, comparison module circuit, at last the signal driver single-chip microcomputer that obtains are analyzed and are counted, and analyze the waveform that produces, parameter is processed, and formed various control signals to realize the wagon flow quantitative statistics.
The below is former to the circuit of the utility model each several part module to be and the control program of single-chip microcomputer is elaborated as follows:
One, pyroelectric infrared sensor
Referring to shown in Figure 3,1 pair of power supply of capacitor C carries out filtering, and+5 V power supply flow sensor power ends enter operational amplifier U 1 after the low-pass filtering of output terminal through resistance R 3 and capacitor C 5.
According to operational amplifier character, when sensor does not produce pulse signal, namely in-phase input end (No. 12 pin of U 1D) is when being direct current signal, the voltage of inverting input and in-phase input end equate, and generation current not on this moment resistance R 4 and the R 5, the output voltage of operation amplifier (No. 14 pins of U 1D) equals the magnitude of voltage of input signal.
When sensor signal produces pulse, the voltage of in-phase input end raises suddenly, this moment, the voltage of inverting input also increased, within the of short duration time, the voltage at capacitor C 2 two ends can not raise immediately, at this in a flash, capacitor C 2 is equivalent to short circuit, the input voltage of in-phase input end equates with resistance R 4 both end voltage, again owing to flowing through the electric current of resistance R 5 and flowing through equating of resistance R 4, so the time resistance R 5 two ends voltage be 220 times of resistance R 4 both end voltage, also just formed approximately 220 times the amplification of input signal to in-phase input end.
Two, every straight amplifying circuit
Referring to Fig. 5, this illustrates the circuit theory every straight amplifying circuit that the utility model embodiment provides.
Among Fig. 5, the signal that socket JP 4 sends for infrared sensor, capacitor C 7 plays the effect of isolated DC, the alternating current-direct current mixed signal of infrared sensor output is become AC signal, if capacitor C 7 capacitances are excessive, the DeGrain of isolated DC signal, the too small meeting of capacitance rising cutoff frequency, useful signal can not normally be passed through, and can prolong the response time.
Through repeatedly experiment, 0.1 uF is suitable for the electric capacity value.Resistance R 14 discharges and recharges passage for capacitor C 7 provides, and guarantees the circuit normal operation, and resistance is crossed conference and caused the response time long, and resistance is crossed small-signal and can be flowed directly into power supply ground and not enter amplifier, and through experiment, 100 K are suitable for the R14 value.
Pyroelectric infrared sensor imports signal into circuit, enters every straight amplifying circuit from socket JP4, but is the mixed signal of AC and DC at input end.When have car under the pyroelectric infrared sensor through out-of-date, can produce a pulse, peak-to-peak value is 300 mV approximately, DC component is 0.8 V approximately.Through capacitor C 7, the DC component of signal can be filtered out, by resistance R 14, for providing, electric capacity discharges and recharges passage, guarantee the normal operation of circuit.Then the in-phase input end of processed signal input operational amplifier.Because the effect of electric capacity and resistance, this moment, the DC component of signal was cut, and peak-to-peak value is about 50 mV.But this moment, signal amplitude was very little, needed to amplify about 50 times.In this circuit, use operational amplifier LM 324 to realize the amplification of small-signal.Can change enlargement factor by the resistance that changes slide rheostat.
Be 50 in order to make enlargement factor, resistance is adjusted to and approximately is respectively 9.8K and 200 Ω.Peak-to-peak value is amplified to 2 V, satisfies the requirement of comparison module circuit.
Three, comparison module circuit
(1) digital regulation resistance
Digital regulation resistance is actually one by monolithic processor controlled potentiometer, and the maximum value of X 9313 is 10 K.Be digital regulation resistance by Single-chip Controlling with the key distinction of common potentiometer, the variation of electricity consumption signal controlling resistance, the signal of adjusting is more accurate.The output voltage of digital regulation resistance is the dividing potential drop of the current resistance of digital regulation resistance in circuit.
As shown in Figure 6, X 9313 is digital regulation resistance, and No. 8 pin Vcc are power supply; No. 4 pin GND ground connection; No. 5 pin VW are the Voltage-output pin; No. 7 pin CS are chip selection signal, ground connection; No. 2 pin UD is the rise and fall control input end, for output increases progressively, successively decreases for output during low level during high level, is controlled by single-chip microcomputer P1.1 mouth; No. 1 pin INC is clock signal, is controlled by single-chip microcomputer P1.0 mouth; No. 3 pin VH and No. 6 pin VL are respectively high voltage input and low-voltage input, and output voltage will change between high low-voltage input.Because the resistance of digital regulation resistance is about 10K, after being connect 10 K resistance, VH meets Vcc, with ground connection behind the VL termination 20K resistance, thereby with the power supply dividing potential drop of 5 V.After tested, high voltage is 4.75 V, and low-voltage is 2.5 V, and digital regulation resistance will be equally divided into 32 parts between the high-low level, owing to high low voltage range is dwindled, so that the precision of digital regulation resistance improves.When the clock signal comes a pulse, if No. 2 pin UD connect high level, then output voltage increase high low-voltage difference 1/32, namely be about 0.04 V; If No. 2 pin UD connects low level, then output voltage reduces by 0.04 V.
The parameter of digital regulation resistance is selected very important, and it directly affects the reliability of device.Threshold value is too high, and then sensitivity is low, although undesired signal suppresses to some extent to external world, but the responding ability to signal weakens, even can not respond, if threshold value is too low then highly sensitive, interference rejection capability weakens to external world, as long as there is the undesired signal input in the external world, then just might produce maloperation.X9313 has 32 resistance values, and resistance value can be controlled by external digital signal, and the resistance value that chooses is stored in the storer, can repeat to call.
(2) window comparator circuit
When pyroelectric infrared sensor detected vehicle, the vehicle infrared radiation that will be surveyed and receive by sensor was transformed into faint voltage signal, and the field effect transistor in being contained in sensor is amplified backward outer output.Because sensor may produce output signal to the interference of photo-thermal and other objects, so add window comparator circuit, signal is screened, and improves the precision of measuring.
The signal that pyroelectric infrared sensor sends will arrange first quiescent point after amplifying circuit amplifies signal, to satisfy the requirement of window comparator circuit.
Signal after at first will amplifying connects capacitor C 8 and removes flip-flop, then with the resistance of resistance R 4 and 19 two 100 K of resistance R, accesses such as Fig. 7, so that the direct current quiescent point is raised to 2.5 V.The value of resistance must be enough large, otherwise useful signal is disappeared.Output terminal access voltage comparator with this signal and digital regulation resistance.In this circuit, voltage comparator adopts LM324 integrated computation amplification chip (U3B among Fig. 7), and through the sensitivity of reference voltage regulator potentiometer regulating circuit, namely investigative range.
When not having vehicle to enter, No. 6 pin voltage of operational amplifier are about 2.5 V; The voltage that the adjusting digital regulation resistance makes No. 5 pins is a little more than 2.5 V, and this moment, No. 7 pins were output as high level.When having vehicle to enter investigative range, infrared sensor output detecting voltage makes inverse output terminal voltage be higher than the voltage of in-phase input end after amplifying, and at this moment output end voltage saltus step is low level, produces negative edge, thereby triggers singlechip interruption.Because operational amplifier connects negative supply, output may be negative value, can damage the external interrupt of single-chip microcomputer, therefore interpolation diode D3 and current-limiting resistance R 17 make negative voltage be no more than-0.7 V as clamping circuit, and the protection single-chip microcomputer; Whether at last, signal enters single-chip microcomputer external interrupt INT 0, be used for detecting vehicle and enter.
Four, the display circuit of display
Referring to shown in Figure 8, among the utility model embodiment, it is power supply ground that display chip adopts 12864, No. 1 pins of serial LCD chip, and No. 2 pins are positive supply, and No. 3 pin is regulated input voltage by slide rheostat RW1, the contrast of control liquid crystal display; No. 4 pin CS are chip selection signal, and by the control of single-chip microcomputer P0.0 mouth, No. 5 pin SID are the serial data mouth, and by the control of single-chip microcomputer P0.1 mouth, No. 6 pin CLK are clock signal, are controlled by single-chip microcomputer P0.3 mouth.In the utility model, use serial mode, No. 15 pin PSB is used for the parallel or working method of serial of choice for use, connects all the time low level; No. 16 pin NC is unsettled; No. 17 pin RET reseting pin and No. 18 pin Vout negative pressure output pin also needn't use; No. 19 pin LED_ K and No. 20 pin LED_ K are that LED-OV and backlight are anodal, connect together+5 V VDD-to-VSSs with No. 1, No. 2 pins respectively.
Five, memory circuitry
Shown in Fig. 9 ~ 10, memory chip 24C256 is a 256K bit serial CMOS EPROM, and 32768 bytes are contained in inside.Concrete method of attachment and pin function are: No. 4 pin GND are power supply ground; No. 8 pin Vcc are positive supply; No. 1 pin and No. 2 pin A 0 and A 1 are address input line; these pins are hardwired or do not connect; for 4 24C256 devices of the maximum addressables of unibus system; here directly be set to low level; the address is 00; No. 7 pin WP are write-protect; here connect low level, close write-protect, allow device to carry out write operation; No. 6 pin SCL are serial clock input pins; for generation of the clock that all data of device send or receive, by the P0.4 mouth control of single-chip microcomputer, No. 5 pin SDA are bidirectional linked list data/address signals; be used for the sending and receiving of all data of device, controlled by single-chip microcomputer P0.5 mouth.
Six. the software control flow process of single-chip microcomputer
When carrying out Software for Design based on single-chip microcomputer, all software programs all use the C language compilation, to reach the function that shows vehicle flowrate and the speed of a motor vehicle.Control program comprises 2 external interrupt triggers, initialization subroutine, digital regulation resistance adjusting program and liquid crystal display program etc.
(1) down trigger mode
Because vehicle at first can pass through pyroelectric infrared sensor 1, when system is in the state that the wait vehicle crosses, only have INT 1 just can finish counting for open mode.Can design thus, the main contents of principal function are the initialization of each element and digital regulation resistance, progressively reduce digital regulation resistance voltage to suitable value, and the initial value that demonstration is set is 0.Finish assignment and the demonstration of vehicle flowrate and vehicle speed initial value, enter at last circulation.
In the digital regulation resistance initialization, the output voltage of digital regulation resistance is divided into 32 lattice with the voltage of 2.5 V～3.75 V, and every lattice are 0.04 V approximately.Because the initial output voltage of digital regulation resistance is unknown, therefore in initialize routine, at first the output voltage with digital regulation resistance rises to the 32nd the highest lattice, namely 3.75 V make its decline afterwards in master routine.Requirement according to sensitivity is different, and fall is also different.For example, if descend 26 lattice, namely use the 8th lattice, this moment, the threshold voltage of digital regulation resistance output was 2.5 V+0.04 V * 8=2.82 V.
(2) external interrupt INT 1 program
Referring to shown in Figure 11, the figure shows the flow process of single-chip microcomputer external interrupt INT 1 program.
After opening external interrupt INT 1, this moment, system began to wait for crossing of vehicle, when vehicle crosses pyroelectric infrared sensor 1, can produce pulse signal, and by shaping, produced negative edge, and negative edge will be identified, thereby produced external interrupt INT 1.Close external interrupt 1 this moment, opening timing device 0, the timer initial value is set and starts timer 0, the vehicle flowrate number adds 1, open external interrupt INT 0 and wait for that vehicle is by another pyroelectric infrared sensor, and the triggering mode of external interrupt INT 0 is set, at last the vehicle flowrate data upgraded are sent into display and shown through the display circuit of display.
(3) external interrupt INT 0 program
Referring to shown in Figure 12, the figure shows the flow process of single-chip microcomputer external interrupt INT 0 program.
After opening external interrupt INT 0, system begins to wait for that vehicle crosses from infrared sensor 2, when vehicle crosses, pyroelectric infrared sensor can produce pulse signal, equally by shaping, produces negative edge, negative edge will be identified, and interrupts thereby produce INT 0.Have no progeny in the generation and close external interrupt, the timeing closing device, and calculate the speed of a motor vehicle with the data based formula v=s/t in the timer register, s is that variable is wide here, the overline bridge width of namely measuring; T is the timer measurement of measuring through the time that the crossover-passing width consumes.The speed of a motor vehicle that calculates is sent into the variable multiplier, and the data of the vehicle speed that upgrades are sent into display and show.
Referring to shown in Figure 13, master control program uses cyclic query mode, circular wait.When the P03 mouth is low level, illustrated that vehicle arrives, start timer, vehicle flowrate adds 1, update displayed vehicle flowrate, circular wait.When the P20 mouth becomes low level, illustrate that vehicle rolls away from, with distance/Time Calculation speed of a motor vehicle, the update displayed speed of a motor vehicle.
Among the utility model embodiment, digital regulation resistance is divided into 32 shelves, the output voltage range of adjustment is 2.5 V-3.75 V, and voltage is defined as the 1st grade when being 2.5 V, and voltage is defined as the 32nd grade when being 3.75 V.The regulation voltage span is 1.25V, that is to say, and one grade of the every rising of digital regulation resistance, output voltage increases 0.04V.For example, second gear voltage is 2.5 V+0.04 V=2.54 V.Initial voltage and the corresponding voltage of each grade of digital regulation resistance are set.
By the actual test to the different time environment, find following rule: 14 o'clock in the afternoon, this moment, solar irradiation was the strongest, ambient temperature is the highest, and digital regulation resistance tap initial position is the 6th grade, so that threshold voltage is 2.74v, as disturbed and transfer at most the 8th grade, threshold voltage is 2.82 V.At late 23 o'clock, digital regulation resistance tap initial position was 4 grades, and threshold voltage is 2.66v, as disturbed and transfer at most the 5th grade or the 6th grade.
In the reality test, the adjusting of sensitivity bothers, and sensitivity is too high may to cause the pulse error count, and sensitivity is crossed to hang down and may easily be leaked meter; And different time, different location, Various Seasonal, all different to the requirement of sensitivity.Therefore, must correct this phenomenon, reach the effect of automatic straightening sensitivity.
At first the initial value of digital regulation resistance is made as very sensitively, has then judged whether pulse error count phenomenon, namely whether in the situation that there is not car that counting has occured.
Determination methods is as follows: if per 30 seconds an of road can not surpass 20 by vehicle flowrate, if the vehicle flowrate that system detects in 30 seconds, illustrates the situation that the vehicle error count occurred greater than 20, at this moment will reduce the sensitivity of 1 lattice.Can automatically be adjusted to suitable sensitivity by this method.
The above only is preferred implementation of the present utility model; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the utility model principle; can also make some improvements and modifications, these improvements and modifications also should be considered as protection domain of the present utility model.
Claims (5)
1. the traffic flow detecting device based on infrared sensor is characterized in that, comprises that two are separated by a distance pyroelectric infrared sensor, a single-chip microcomputer and a display that is installed on road top or side; Export respectively a pulse signal when described two pyroelectric infrared sensors are used for detecting vehicle and sail into and send into described single-chip microcomputer; Described single-chip microcomputer is used for calculating vehicle according to described pulse signal and calculates the speed of a motor vehicle by number and according to vehicle by the time of described two pyroelectric infrared sensors, the distance of described two pyroelectric infrared sensors, and sends into described display demonstration.
2. the traffic flow detecting device based on infrared sensor according to claim 1, it is characterized in that, comprise a signal processor, be used for pulse signal with described pyroelectric infrared sensor output carry out every straight amplification, compare Screening Treatment after the described single-chip microcomputer of input.
3. the traffic flow detecting device based on infrared sensor according to claim 2 is characterized in that, described signal processor includes:
Every straight amplifying circuit, be used for the pulse signal of described pyroelectric infrared sensor output is carried out exporting to the comparison module circuit after straight amplification;
The comparison module circuit is used for described pulse signal every straight amplification and threshold voltage are compared, but inputs to described single-chip microcomputer after filtering out described single-chip microcomputer processing signals.
4. the traffic flow detecting device based on infrared sensor according to claim 3, it is characterized in that, described comparison module circuit comprises window comparator circuit and a digital regulation resistance, described digital regulation resistance is used for the threshold voltage of using when described window comparator circuit comparison Screening Treatment signal is adjusted in control by described Single-chip Controlling.
5. each described traffic flow detecting device based on infrared sensor is characterized in that according to claim 1 ~ 4, and described display is LCD display.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102789691A (en) * | 2012-08-21 | 2012-11-21 | 北京信息科技大学 | Detecting method and detecting system of flow and speed of vehicles |
| CN104680799A (en) * | 2013-11-29 | 2015-06-03 | 青岛永通电梯工程有限公司 | Vehicle flow detection method |
| CN105046960A (en) * | 2015-07-10 | 2015-11-11 | 潘进 | Method and apparatus for analyzing road congestion state and detecting illegal parking |
| CN108242155A (en) * | 2016-12-23 | 2018-07-03 | 吴若父 | A kind of overspeed monitor for velocity tunnel |
| CN108281013A (en) * | 2018-03-22 | 2018-07-13 | 安徽八六物联科技有限公司 | A kind of road traffic monitoring system |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102789691A (en) * | 2012-08-21 | 2012-11-21 | 北京信息科技大学 | Detecting method and detecting system of flow and speed of vehicles |
| CN104680799A (en) * | 2013-11-29 | 2015-06-03 | 青岛永通电梯工程有限公司 | Vehicle flow detection method |
| CN105046960A (en) * | 2015-07-10 | 2015-11-11 | 潘进 | Method and apparatus for analyzing road congestion state and detecting illegal parking |
| CN105046960B (en) * | 2015-07-10 | 2018-03-02 | 武汉微智创大科技有限公司 | A kind of method and device detected to congestion in road state analysis and illegal parking |
| CN108242155A (en) * | 2016-12-23 | 2018-07-03 | 吴若父 | A kind of overspeed monitor for velocity tunnel |
| CN108281013A (en) * | 2018-03-22 | 2018-07-13 | 安徽八六物联科技有限公司 | A kind of road traffic monitoring system |
| CN109930538A (en) * | 2019-04-02 | 2019-06-25 | 绍兴职业技术学院 | A kind of sprinkling truck variable spray system |
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