CN100559417C - The magnitude of traffic flow, vehicle speed measurement wireless sensor node - Google Patents
The magnitude of traffic flow, vehicle speed measurement wireless sensor node Download PDFInfo
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- CN100559417C CN100559417C CNB2007100100866A CN200710010086A CN100559417C CN 100559417 C CN100559417 C CN 100559417C CN B2007100100866 A CNB2007100100866 A CN B2007100100866A CN 200710010086 A CN200710010086 A CN 200710010086A CN 100559417 C CN100559417 C CN 100559417C
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Abstract
The present invention relates to signal acquisition and processing apparatus, the magnitude of traffic flow, vehicle speed measurement wireless sensor node, it is characterized in that: it is made up of microprocessor, sensor unit, Transmit-Receive Unit and power supply unit, power supply unit is respectively microprocessor, sensor unit and Transmit-Receive Unit power supply is provided, sensor unit is that magnetoresistive transducer inputs to microprocessor behind the two-stage amplifier amplifying signal, microprocessor is by the signal of the A/D converter pick-up transducers unit that carries, information is sent to Transmit-Receive Unit after treatment, and Transmit-Receive Unit sends signal to appointment place.Wireless sensor node of the present invention, simple in structure, easy to install and use, cheap, non-cpntact measurement, measuring accuracy height can be organized into network and realize monitoring on a large scale, not influenced by adverse weather condition, have very big application and popularization value.
Description
Technical field:
The present invention relates to signal acquisition and processing apparatus, especially for the measurement mechanism of on-highway motor vehicle flow and travel speed.
Background technology:
Traffic information acquisition system is a vital link in the intelligent transportation system overall architecture, and traffic information promptly and accurately is the basis that intelligent transportation system is efficiently brought into play the traffic control effect.Wagon detector commonly used at present has toroid winding detector, microwave detector, ultrasonic detector and video detector etc.Consider from cost performance and high reliability, use maximum toroid winding detector, its technology maturations of remaining now, the accuracy of detection height, equipment price is low, but all weather operations, but need cut the road surface when installing, influence pavement life, and installation process is very big to coil reliability and life-span influence, installation and maintenance is difficulty relatively, in addition, toroid winding can only carry out the bicycle road to be measured, and needs a plurality of sensors under the multilane measurement situation, and cost is very high.Ultrasonic detector adopts suspension type to install, and need not to destroy the road surface, and the measuring accuracy height can detect the very little wagon flow of spacing, and its deficiency is can't normally detect when wind speed is excessive, and the object of probe below also can produce reflection wave, causes flase drop.But microwave detector operate as normal still under rugged surroundings can realize that multilane detects.Video detector is powerful, and image is directly perceived, and installation and maintenance do not destroy the road surface, and a video camera can cover 6 tracks, is applicable to the traffic control of city intersection, but is subject to the weather extremes influence, and requiring night provides enough brightness for the road surface.The above-mentioned general value of vehicle detector at present commonly used is relatively more expensive, generally is arranged in the city intersection place, can not reflect vehicle away from the travel situations in the highway section of intersection, and the measuring accuracy of some detectors also can be subjected to the influence of weather conditions.
Summary of the invention:
The objective of the invention is to overcome above-mentioned not enough problem, a kind of magnitude of traffic flow, vehicle speed measurement wireless sensor node are provided, simple in structure, easy to install and use, cheap, be not subjected to surrounding environment, climatic influences, safe and reliable.
The technical scheme that the present invention is adopted for achieving the above object is: the magnitude of traffic flow, vehicle speed measurement wireless sensor node, form by microprocessor, sensor unit, Transmit-Receive Unit and power supply unit, power supply unit is respectively microprocessor, sensor unit and Transmit-Receive Unit power supply is provided, sensor unit is that magnetoresistive transducer inputs to microprocessor behind the two-stage amplifier amplifying signal, microprocessor is by the signal of the A/D converter pick-up transducers unit that carries, information is sent to Transmit-Receive Unit after treatment, and Transmit-Receive Unit sends signal to appointment place.
Described sensor unit also is equipped with the refresh pulse generator and links to each other with magnetoresistive transducer, and the refresh pulse generator is controlled by microprocessor, is used for regularly recovering the detection sensitivity of magnetoresistive transducer.
Described sensor unit is equipped with two magnetoresistive transducers of 10-15 centimetre apart, two magnetoresistive transducers respectively connect an one-level amplifier one stage signal and amplify, after same pair of computing two-stage amplifier amplifies, signal is transferred to microprocessor again, refresh pulse generator of microprocessor control, the refresh pulse generator is connected with two magnetoresistive transducers respectively.
The microprocessor control program is that first vehicle passes through, just start timer immediately and write down the moment that vehicle passes through, gather the output signal of rear end magnetic field sensor then, after vehicle detecting algorithm detected vehicle, microprocessor stopped the timer timing, by length of following time of timer record, calculate the size of the speed of a motor vehicle, after this, microprocessor is reduced to original frequency with sample frequency, restart the counting work of vehicle, finish until dormancy time.
Described power supply unit is a disposable lithium cell; The voltage of disposable lithium cell output carries out supplying power to power unit after the voltage adjustment through the DC voltage-stabilizing chip.
Described Transmit-Receive Unit is a wireless transmit/receive units, adopts little power consumption radio frequency chip nRF905 to carry out radio communication.
Have bonded adhesives on the described wireless sensor node housing.
Wireless sensor node of the present invention can directly stick with glue on carriageway surfacing, and by the disposable lithium cell power supply, measurement data sends by wireless communication unit, has so just greatly simplified the installation of wireless sensor node.Because sensor node is by powered battery, energy-conservation is the problem that will consider emphatically, therefore, has selected little power consumption components and parts on the hardware design of wireless sensor node of the present invention as far as possible for use.
Wireless sensor node of the present invention can accurately be surveyed flow motor and travel speed; Utilize wireless communication technology to finish the transmission of measurement data, and the dependence powered battery makes that on-the-spot installation is very convenient, can be arranged in each highway section of avenue easily, rather than only be confined to the intersection, and can be organized into network realization monitoring on a large scale.Because this wireless sensor node is simple in structure, easy to install and use, cheap, not only be convenient to produce, and wireless sensor node utilizes magnetoresistive transducer to survey surrounding environment magnetic field, through out-of-date, can detect the field signal of a sudden change as automobile.A kind of non-cpntact measurement device of this wireless sensor node, cheap, measuring accuracy is high, not influenced by adverse weather condition, has very big application and popularization value.
Description of drawings:
Fig. 1 is a structural representation of the present invention.
The change curve of field signal when the vehicle that Fig. 2 obtains for the present invention's actual measurement passes through.
Fig. 3 is a microprocessor control program block diagram of the present invention.
Fig. 4 is the continuous figure of Fig. 3.
Embodiment:
Wireless sensor node as shown in Figure 1, the magnitude of traffic flow, vehicle speed measurement wireless sensor node, by microprocessor 3, sensor unit 1, Transmit-Receive Unit 4 and power supply unit 2 are formed, it is the disposable lithium cell 5 of ER14505 that power supply unit adopts battery size, the lithium battery output voltage is 3.6V, after being 3.3V voltage, the treatment conversion of change in voltage integrated circuit TPS60101 supplies microprocessor, sensor unit and wireless transmit/receive units use, sensor unit is equipped with two magnetoresistive transducers 8 of 10 centimetres apart, magnetoresistive transducer is the U.S. novel magnetoresistive transducer HMC1021 of Newire Inc.'s production suddenly, two magnetoresistive transducers respectively meet an one-level amplifier 9 instrumentation amplifier INA155 and carry out the one stage signal amplification, carry out after second signal amplifies signal being transferred to microprocessor through same pair of computing two-stage amplifier 7 (OPA262) again, refresh pulse generator 6 on the microprocessor control sensor unit, the refresh pulse generator is connected with two magnetoresistive transducers respectively.Microprocessor is embedded MSP430F149, and shown in Fig. 3,4, microprocessor receiving sensor unit information is sent to Transmit-Receive Unit after treatment, and Transmit-Receive Unit sends signal to appointment place.The microprocessor control program is that first vehicle passes through, just start timer immediately and write down the moment that vehicle passes through, gather the output signal of rear end magnetic field sensor then with the sample frequency of 1KHz, after vehicle detecting algorithm detects vehicle, microprocessor just stops the timer timing, the time length of noting by timer like this, just can calculate the size of the speed of a motor vehicle, after this, microprocessor is reduced to 100Hz with sample frequency, restart the counting work of vehicle, finish until 1 minute dormancy time.
Transmit-Receive Unit is a wireless transmit/receive units, adopts little power consumption radio frequency chip nRF905 and dual-mode antenna 10 to carry out radio communication.Have bonded adhesives on the wireless sensor node housing.
As shown in Figure 2, when not having vehicle through sensor node, field signal fluctuates in certain scope, and through out-of-date, tangible positive negative pulse stuffing signal just can appear in field signal as vehicle.When the vehicle forward passed through sensor node, direct impulse appearred earlier in field signal, and follows a reverse impulse closely, and the order that positive negative pulse stuffing occurs when vehicle oppositely passes through is opposite.
Core of the present invention is Low Power Embedded Microprocessor MSP430F149, it changes carrying out digital-to-analogue based on the output signal of the sensing unit of magnetoresistive transducer HMC1021, and the signal of gathering carried out analyzing and processing, obtain information such as flow motor, average speed, by wireless transmit/receive units analysis result is sent then.The core devices of radio frequency units is nRF905, and it can realize the physical layer function of cordless communication network, and the data that send from microprocessor are packed, and adds control prefix and redundancy check code, and finishes the bit wireless transmission at the ISM wave band.Magnetoresistive transducer HMC1021 is the U.S.'s novel magnetoresistive transducer of Newire Inc.'s production suddenly, its sensing mechanism is four arm Wheatstone bridges that are made of mistor, magnetic field can be converted to differential output voltage, it can detect the magnetic field that is low to moderate 85 microgasusses, and measurement range is ± 6 Gausses.Can satisfy high precision, the requirement of high reliability has small chip volume and very little power consumption again.Instrumentation amplifier INA155 can amplify the differential wave of HMC1021 output, and differential signal is converted to single-ended output signal, thereby can further further be amplified by little power consumption operational amplifier OPA262.As seen from Figure 1, a vehicle detection wireless sensor node disposes two HMC1021 magnetoresistive transducers, a front end that is positioned at wireless sensor node, and another is positioned at the rear end, and the two is at a distance of 10 centimetres, and the purpose of She Zhiing is in order to realize vehicle speed measurement like this.Because OPA262 is a double operational, the two-way field signal uses the amplifier of this OPA262 to realize that secondary amplifies respectively like this, has saved the number of the amplifier chip that uses.Field signal after OPA262 amplifies is admitted to the A/D converter that MSP430F149 carries, and is converted into digital signal under the control of trace routine, through the processing of data processing algorithm, obtains vehicle flowrate and speed information, and sends to wireless transmit/receive units.
The measurement result of wireless sensor node sends by the wireless transmit/receive units of being made up of nRF905, owing to adopted communication, contiguous wireless sensor node can be organized into network, this not only can realize large-range measuring, and helps to simplify the program design of wireless sensor node passback measurement data.In the present invention, nRF905 is configured to work in the 433MHz frequency range, and this frequency range need not application, can freely use.NRF905 this as little power consumption chip, but in this wireless sensor node, remain the main element of power consumption.Wireless communication unit can consume more energy in transceive data with when being in idle condition, and therefore, microprocessor can be when not using wireless communication unit, and nRF905 is set to dormant state, realizes energy-conservation.
Because magnetoresistive transducer in use for some time, or be subjected to the influence of high magnetic field intensity, detection sensitivity can descend greatly, thereby influences the precision of vehicle detection.A refresh pulse generator is housed among the present invention, can produces an of short duration current impulse under the control of microprocessor, through the effect of this current impulse, magnetoresistive transducer can recover high measurement sensitivity again.
Be a bit of source program below:
P1OUT&＝~TRX_CE；
TimerA_Flag＝0；
CCRO＝6555；
Standby_Mode()；
Send_Mode()；
TxAdress()；
SendData(Message)；
P1OUT|＝TRX_CE；
Delay_us(50)；
P1OUT&＝~TRX_CE；
Delay_us(800)；
while((P2IN&0x04)＝＝0)；
Power_Off()；
P6OUT&＝~TX；
Claims (5)
1, the magnitude of traffic flow, vehicle speed measurement wireless sensor node, it is characterized in that: it is by microprocessor (3), sensor unit (1), Transmit-Receive Unit (4) and power supply unit (2) are formed, power supply unit is respectively microprocessor, sensor unit and Transmit-Receive Unit provide power supply, sensor unit is that magnetoresistive transducer (8) inputs to microprocessor behind the two-stage amplifier amplifying signal, microprocessor is by the signal of the A/D converter pick-up transducers unit that carries, information is sent to Transmit-Receive Unit after treatment, Transmit-Receive Unit sends signal to appointment place, the microprocessor control program is that first vehicle passes through, just start timer immediately and write down the moment that vehicle passes through, gather the output signal of rear end magnetic field sensor then with sample frequency, after vehicle detecting algorithm detects vehicle, microprocessor just stops the timer timing, by length of following time of timer record, calculate the size of the speed of a motor vehicle, after this, microprocessor is reduced to original frequency with sample frequency, restart the counting work of vehicle, finish until dormancy time.
2, the magnitude of traffic flow according to claim 1, vehicle speed measurement wireless sensor node is characterized in that: power supply unit (2) power supply is disposable lithium cell (5).
3, the magnitude of traffic flow according to claim 2, vehicle speed measurement wireless sensor node is characterized in that: the voltage of disposable lithium cell output carries out supplying power to power unit after the voltage adjustment through the DC voltage-stabilizing chip.
4, the magnitude of traffic flow according to claim 1, vehicle speed measurement wireless sensor node is characterized in that: Transmit-Receive Unit (4) is a wireless transmit/receive units, adopts little power consumption radio frequency chip nRF905 to carry out radio communication.
5, the magnitude of traffic flow according to claim 1, vehicle speed measurement wireless sensor node is characterized in that: have bonded adhesives on the wireless sensor node housing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2007100100866A CN100559417C (en) | 2007-01-16 | 2007-01-16 | The magnitude of traffic flow, vehicle speed measurement wireless sensor node |
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2007100100866A CN100559417C (en) | 2007-01-16 | 2007-01-16 | The magnitude of traffic flow, vehicle speed measurement wireless sensor node |
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| Publication Number | Publication Date |
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| CN101025863A CN101025863A (en) | 2007-08-29 |
| CN100559417C true CN100559417C (en) | 2009-11-11 |
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| CNB2007100100866A Expired - Fee Related CN100559417C (en) | 2007-01-16 | 2007-01-16 | The magnitude of traffic flow, vehicle speed measurement wireless sensor node |
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Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101694746A (en) * | 2009-10-19 | 2010-04-14 | 浙江大学 | Magnetic resistant vehicle quantity and speed detecting node based on Zigbee wireless protocol and use methods thereof |
| CN103123743A (en) * | 2012-12-11 | 2013-05-29 | 武汉智慧城市研究院股份有限公司 | Vehicle counting system and method based on wireless sensor network |
| CN103247180A (en) * | 2013-05-10 | 2013-08-14 | 秦旭彦 | Micropower wireless geomagnetism traffic flow detector |
| CN103268705A (en) * | 2013-05-10 | 2013-08-28 | 秦旭彦 | Self-power-generation wireless geomagnetic traffic flow detector |
| US10557725B2 (en) * | 2014-11-24 | 2020-02-11 | Sensitec Gmbh | Magnetoresistive wheatstone measuring bridge and angle sensor having at least two such measuring bridges |
| CN104835326A (en) * | 2015-04-24 | 2015-08-12 | 周欣 | Vehicle detector based on anisotropy magnetic resistance sensor array |
| FR3049750B1 (en) * | 2016-03-31 | 2018-04-27 | Eco Compteur | DETECTION SYSTEM FOR PASSING A BIKE |
| CN108776196A (en) * | 2018-05-31 | 2018-11-09 | 深圳市沃特沃德股份有限公司 | Drunk driving self-checking system based on short-distance wireless communication and method |
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Granted publication date: 20091111 Termination date: 20120116 |