CN107331160A - The method and apparatus that car speed is measured based on single geomagnetic sensor - Google Patents
The method and apparatus that car speed is measured based on single geomagnetic sensor Download PDFInfo
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- CN107331160A CN107331160A CN201710762178.3A CN201710762178A CN107331160A CN 107331160 A CN107331160 A CN 107331160A CN 201710762178 A CN201710762178 A CN 201710762178A CN 107331160 A CN107331160 A CN 107331160A
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- G—PHYSICS
- G08—SIGNALLING
- G08G—TRAFFIC CONTROL SYSTEMS
- G08G1/00—Traffic control systems for road vehicles
- G08G1/01—Detecting movement of traffic to be counted or controlled
- G08G1/042—Detecting movement of traffic to be counted or controlled using inductive or magnetic detectors
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- G—PHYSICS
- G08—SIGNALLING
- G08G—TRAFFIC CONTROL SYSTEMS
- G08G1/00—Traffic control systems for road vehicles
- G08G1/01—Detecting movement of traffic to be counted or controlled
- G08G1/052—Detecting movement of traffic to be counted or controlled with provision for determining speed or overspeed
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Abstract
The invention discloses a kind of method and apparatus that car speed is measured based on single geomagnetic sensor, belong to intelligent traffic vehicle detection field.The method for measuring car speed based on single geomagnetic sensor includes：Step 1：Geomagnetic field intensity in multiple cycles that geomagnetic sensor is gathered in real time is obtained, the geomagnetic sensor is used to be arranged under road；Step 2：Calculating obtains geomagnetic field intensity rate of change；Step 3：According to the geomagnetic field intensity rate of change and the relation of car speed of resulting geomagnetic field intensity rate of change, and measured in advance, car speed is calculated.The present invention takes full advantage of that vehicle speed is small to the shock wave rule in earth's magnetic field, construction volume, construction cost is low.
Description
Technical field
The present invention relates to intelligent traffic vehicle detection technique field, particularly relate to a kind of based on single geomagnetic sensor measurement car
The method and apparatus of speed.
Background technology
High speed development and the continuous expansion of city size with social economy, urban transport problems is also with increasingly tight
Weight.Wherein, distinct issues are the traffic safety problems in city the most.And the accurate detection of vehicular traffic travel speed is traffic
The powerful guarantee of safety, is also the important step of intelligent transportation system.
At present, it is using the traditional approach of geomagnetic sensor measurement speed：It will be arranged before and after two geomagnetic sensors difference,
Bury below road, and certain distance d is kept between two geomagnetic sensors, when vehicle is travelled on road, first pass through
One of geomagnetic sensor, during by this geomagnetic sensor, vehicle can produce disturbance to sending out earth's magnetic field near geomagnetic sensor,
Geomagnetic sensors detection judges that vehicle passes through to disturbance of this vehicle to earth's magnetic field, starts timing, vehicle is therewith by another
During geomagnetic sensor device, when the geomagnetic sensors detection to vehicle is to the disturbance in earth's magnetic field, timing terminates.By above-mentioned detection
Process can obtain vehicle successively by the time t used in two geomagnetic sensors, then can be tried to achieve by formula v=d/t
The speed of vehicle.
The method of traditional measurement speed has used two geomagnetic sensors, and car is measured just with geomagnetic sensor
Disturbance is whether there is to earth's magnetic field and determines whether vehicle process, the not change to the speed of vehicle to the disturbance quantity in earth's magnetic field is carried out more
Plus the analysis of accurate quantification, do not make full use of the rule of vehicle magnetic interference over the ground；Also, surveyed using two geomagnetic sensors
Amount speed needs to bury two geomagnetic sensors below road, more serious to road damage, great in constructing amount, adds and is constructed into
This.
The content of the invention
The present invention provides that a kind of utilization vehicle speed is small to the shock wave rule in earth's magnetic field, construction volume, construction cost is low
Based on single geomagnetic sensor measure car speed method and apparatus.
In order to solve the above technical problems, present invention offer technical scheme is as follows：
On the one hand, the present invention provides a kind of method that car speed is measured based on single geomagnetic sensor, including：
Step 1：Obtain geomagnetic field intensity in multiple cycles that geomagnetic sensor is gathered in real time；The geomagnetic sensor is used for
It is arranged under road；
Step 2：Calculating obtains geomagnetic field intensity rate of change；
Step 3：According to the geomagnetic field intensity rate of change and car of resulting geomagnetic field intensity rate of change, and measured in advance
The relation of speed, calculates car speed.
Further, step 11 is also included between the step 1 and step 2：
Step 11：Determine whether that vehicle passes through according to the geomagnetic field intensity of acquisition, if so, performing step 2, if nothing, hold
Row step 1.
Further, the step 11 is further：
The geomagnetic field intensity that the geomagnetic field intensity that current period is obtained was obtained with a upper cycle is compared, and is set if exceeding
Determine threshold value, then regarded as vehicle process, perform step 2, otherwise, regard as no vehicle and pass through, perform step 1.
Further, the geomagnetic sensor is three axle geomagnetic sensors, and the geomagnetic field intensity is the earth magnetism field strength of X-axis
Degree, the direction of the X-axis of the geomagnetic sensor is parallel with direction of traffic, and the step 2 is further：
Geomagnetic field intensity when judging to have the vehicle pass through is Bnow, make B1=Bnow, from obtaining BnowMoment, Bnow1For most
The new geomagnetic field intensity once gathered, Bpre1For data Bnow1A upper cycle collection geomagnetic field intensity, work as Bpre1-Bnow1>Δ
B1When, wherein, Δ B1For given threshold, B is made2=Bpre1, calculate from there is geomagnetic field intensity BnowStart to there is earth's magnetic field
Intensity Bpre1This period geomagnetic sensor has the geomagnetic field intensity number N of collection altogether, and the geomagnetic field intensity rate of change is：Wherein, BsFor the geomagnetic field intensity rate of change of geomagnetic sensor X-axis, T is the cycle that geomagnetic sensor is sampled.
It is preferred that, in the step 3, the geomagnetic field intensity rate of change B of measured in advancesRelation with car speed v is：
V=aBs 3+bBs 2+cBs+d (1)
Wherein, a, b, c, d are constant；
Constant a, b, c, d determination method are as follows in formula (1)：
Geomagnetic field intensity data under different vehicle speed v are gathered with the same cycle, ground X-axis is tried to achieve according to the step 2
Change rate of magnetic density Bs, obtain multigroup Bs- v data, using least square fitting curve, obtain constant a, b, c, d.
On the other hand, the present invention provides a kind of device that car speed is measured based on single geomagnetic sensor, including：
Acquisition module：For obtaining geomagnetic field intensity in multiple cycles that geomagnetic sensor is gathered in real time；The earth magnetism is passed
Sensor is used to be arranged under road；
First computing module：Geomagnetic field intensity rate of change is obtained for calculating；
Second computing module：For the earth magnetism field strength according to resulting geomagnetic field intensity rate of change, and measured in advance
The relation of rate of change and car speed is spent, car speed is calculated.
Further, the device for measuring car speed based on single geomagnetic sensor also includes：
Judge module：For determining whether that vehicle passes through according to the geomagnetic field intensity of acquisition.
Further, the judge module, is further used for：
The geomagnetic field intensity that the geomagnetic field intensity that current period is obtained is obtained with upper a cycle is compared, if exceeding
Given threshold, then regarded as vehicle process, otherwise, regards as no vehicle and passes through.
Further, the geomagnetic sensor is three axle geomagnetic sensors, and the geomagnetic field intensity is the earth magnetism field strength of X-axis
Degree, the direction of the X-axis of the geomagnetic sensor is parallel with direction of traffic, and first computing module is further used for：
Geomagnetic field intensity when judging to have the vehicle pass through is Bnow, make B1=Bnow, from obtaining BnowMoment, Bnow1For most
The new geomagnetic field intensity once gathered, Bpre1For data Bnow1A upper cycle collection geomagnetic field intensity, work as Bpre1-Bnow1>Δ
B1When, wherein, Δ B1For given threshold, B is made2=Bpre1, calculate from there is geomagnetic field intensity BnowStart to there is earth's magnetic field
Intensity Bpre1This period geomagnetic sensor has the geomagnetic field intensity number N of collection altogether, and the geomagnetic field intensity rate of change is：Wherein, BsFor the geomagnetic field intensity rate of change of geomagnetic sensor X-axis, T is the cycle that geomagnetic sensor is sampled.
It is preferred that, in second computing module, geomagnetic field intensity rate of change B set in advancesWith car speed v pass
It is to be：
V=aBs 3+bBs 2+cBs+d (2)
Wherein, a, b, c, d be constant a, b, c, d in constant, formula (2) determination method it is as follows：
Geomagnetic field intensity data under different vehicle speed v are gathered with the same cycle, asked according to first computing module
Obtain the change rate of magnetic density B of ground X-axiss, obtain multigroup Bs- v data, using least square fitting curve, obtain constant a, b,
c、d。
The invention has the advantages that：
The method and apparatus that car speed is measured based on single geomagnetic sensor of the present invention, using single geomagnetic sensor pair
Car speed is measured, and the influence in earth's magnetic field is quantified using car speed, passes through geomagnetic field intensity rate of change
Car speed is obtained with the relation of car speed, the rule of car speed magnetic fields over the ground, this side is taken full advantage of
Method measurement car speed is all suitable for any vehicle, solves the problem of influence that different automobile types produce to earth's magnetic field is different.
The measurement car speed method of the present invention is reduced under geomagnetic sensor burial ground only with single geomagnetic sensor
Construction volume and the destruction to road, construction cost is low.
Brief description of the drawings
Fig. 1 is the flow chart of the method that car speed is measured based on single geomagnetic sensor of the present invention；
Fig. 2 is the geomagnetic field intensity rate of change of the present invention and the relation schematic diagram of car speed；
Fig. 3 is the earth's magnetic field schematic diagram of the geomagnetic sensor of the present invention.
Embodiment
To make the technical problem to be solved in the present invention, technical scheme and advantage clearer, below in conjunction with accompanying drawing and tool
Body embodiment is described in detail.
On the one hand, the present invention provides a kind of method that car speed is measured based on single geomagnetic sensor, as shown in Figures 1 to 3,
Including：
Step 1：Obtain geomagnetic field intensity in multiple cycles that geomagnetic sensor is gathered in real time；Geomagnetic sensor is used to set
Under road, depth is set to be set according to common knowledge；It is strong that geomagnetic sensor gathers earth's magnetic field in real time with the cycle T set
Spend and gather once, single-chip microcomputer is read once from geomagnetic sensor, it is ensured that its sensitivity detected；
Step 2：Calculating obtains geomagnetic field intensity rate of change；Two adjacent periods can be used when calculating geomagnetic field variation rate
Interior geomagnetic field intensity value is subtracted each other again divided by computation of Period is obtained, or calculates acquisition using other modes；
Step 3：According to the geomagnetic field intensity rate of change and car of resulting geomagnetic field intensity rate of change, and measured in advance
The relation of speed, calculates car speed.
The method that car speed is measured based on single geomagnetic sensor of the present invention, using single geomagnetic sensor to vehicle speed
Degree is measured, and the influence in earth's magnetic field is quantified using car speed, passes through geomagnetic field intensity rate of change and vehicle
The relation of speed obtains car speed, takes full advantage of the rule of car speed magnetic fields over the ground, this method measurement
Car speed is all suitable for any vehicle, solves the problem of influence that different automobile types produce to earth's magnetic field is different.
The measurement car speed method of the present invention is reduced under geomagnetic sensor burial ground only with single geomagnetic sensor
Construction volume and the destruction to road, construction cost is low.
Further, to better implement the present invention, step 11 is also included between step 1 and step 2：
Step 11：Determine whether that vehicle passes through according to the geomagnetic field intensity of acquisition, if so, performing step 2, if nothing, hold
Row step 1.
Further, step 11 is further：
The geomagnetic field intensity that the geomagnetic field intensity that current period is obtained was obtained with a upper cycle is compared, if exceeding
Given threshold, then regarded as vehicle process, performs step 2, otherwise, regards as no vehicle and passes through, performs step 1.Specifically,
When there is vehicle to be travelled from distant place near geomagnetic sensor, the geomagnetic field intensity meeting that geomagnetic sensor is collected with the sampling period
Having significantly strengthens, according to this feature, BnowThe geomagnetic field intensity of the earth's magnetic field X-axis gathered for geomagnetic sensor the last time,
BpreFor data BnowA upper cycle earth's magnetic field X-axis geomagnetic field intensity, work as Bnow-BpreDuring ＞ Δ B, it is determined as that vehicle is passed through
Cross, otherwise, pass through without vehicle, wherein Δ B is to determine whether vehicle by the threshold value set by geomagnetic sensor, and threshold value is big
Small setting can specifically be set according to noisy degree of prevailing circumstances etc., and the size of threshold value does not influence the implementation of the present invention.
If passing through geomagnetic sensor without vehicle, then geomagnetic sensor continues to gather geomagnetic sensor with the sampling period
Neighbouring earth's magnetic field field strength and geomagnetic sensor often gather that a data monolithic is machine-readable to be taken once, and whether monitoring vehicle has in real time
Vehicle passes through.If having detected vehicle by near geomagnetic sensor, then the magnetic field strength date to earth's magnetic field X-axis is carried out
Below deeper into analysis.
It is preferred that, geomagnetic sensor is three axle geomagnetic sensors, and geomagnetic field intensity is the geomagnetic field intensity of X-axis, and earth magnetism is passed
The direction of the X-axis of sensor is parallel with direction of traffic, as shown in figure 3, geomagnetic sensor is buried below road with appropriate depth,
Component schematic diagram of the magnetic field intensity in X, Y, Z axis, it is assumed that total magnetic intensity be component in S, X, Y, Z axis be respectively X1,
Y1, Z1, then meetBecause the direction of X-axis is parallel with direction of traffic, the earth magnetism field data of X-axis is most
It is regular, it is preferred that the geomagnetic field intensity used in the present invention is the geomagnetic field intensity of X-axis；
It is below a kind of specific computational methods for convenience of measurement geomagnetic field intensity rate of change：
Geomagnetic field intensity when judging to have the vehicle pass through is Bnow, make B1=Bnow, from obtaining BnowMoment, Bnow1For most
The new geomagnetic field intensity once gathered, Bpre1For data Bnow1A upper cycle collection geomagnetic field intensity, work as Bpre1-Bnow1>Δ
B1When, wherein, Δ B1For given threshold, B is made2=Bpre1, calculate from there is geomagnetic field intensity BnowStart to there is earth's magnetic field
Intensity Bpre1This period geomagnetic sensor has the geomagnetic field intensity number N of collection altogether, and the geomagnetic field intensity rate of change is：Wherein, BsFor the geomagnetic field intensity rate of change of geomagnetic sensor X-axis, T is the cycle that geomagnetic sensor is sampled.
If it is judged that there is vehicle to be used as the first of calculating rate of change by the geomagnetic field intensity for the point for then passing through vehicle
It is individual, i.e. Bnow, be tested with vehicle through when by meeting given threshold find out the earth's magnetic field X-axis that geomagnetic sensor is gathered
Maximum (the i.e. B of geomagnetic field intensity during this period of timepre1) as second point, subtracted with the geomagnetic field intensity value of second point
The geomagnetic field intensity value divided by this period for removing first point are exactly rate of change, herein, can pass through this period and count sampling
Count to calculate, be (N+1) T.There is vehicle to be opened when passing through it is worth noting that, the computation interval of above-mentioned computational methods is judgement
Begin to stop when there is maximum to the geomagnetic field intensity of the X-axis of certain a period of time, do not arrived for vehicle at the time of the maximum occurs
At the time of directly over up to geomagnetic sensor, therefore, it is desirable to according to the velocity interval of vehicle to be measured, given threshold Δ is rationally set
B1, Δ B1Setting can be according to the velocity interval of vehicle to be measured, and ensure the geomagnetic field intensity maximum B of X-axispre1Appear in car
Reach geomagnetic field intensity directly over before, carry out test of many times, obtain rational given threshold.This computational methods are being taken into account
While simple, accurate rate is higher.
It is preferred that, in step 3, the geomagnetic field intensity rate of change B of measured in advancesRelation with car speed v is：
V=aBs 3+bBs 2+cBs+d (1)
Wherein, a, b, c, d are constant；
Constant a, b, c, d determination method are as follows in formula (1)：
Geomagnetic field intensity data under different vehicle speed v are gathered with the same cycle, the earth magnetism of X-axis is tried to achieve according to step 2
Field intensity rate of change Bs, obtain multigroup Bs- v data, using least square fitting curve, obtain constant a, b, c, d.
Applicant is by lot of experiments discovery, geomagnetic field intensity rate of change BsRelation with car speed v will not be because of car
Type is different, vehicle size is different and changes, as shown in Fig. 2 to test obtained Bs- v data and curves, transverse axis is vehicle speed
Degree, unit km/h, transverse axis is the change rate of magnetic density of geomagnetic sensor X-axis, using least square method to Bs- v data and curves
It is fitted, obtains a=5.35 × 10-6, b=-0.00226, c=0.6457, d=-16.94, that is to say, that using the present invention
Computational methods can shield different automobile types, the vehicle size difference different to geomagnetic field disturbance, only according to change of magnetic field strength
Rate can calculate car speed.
In the present invention, the cycle T that geomagnetic sensor gathers geomagnetic field intensity in real time is 5-20ms；Outside geomagnetic sensor
Portion is provided with sealed insulation device, and geomagnetic sensor can be prevented to be imbedded in underground and penetrated into by rainwater, of the invention based on single
The measurable 0-240km/h of method of Magnetic Sensor measurement car speed speed.
It is worth noting that, the periphery of geomagnetic sensor can set the electronic components such as circuit board, due to being passed by earth magnetism
Sensor measurement geomagnetic field intensity is known technology, herein to the internal structure and measuring principle of geomagnetic sensor, is repeated no more, can
Measured with reference to common knowledge.
On the other hand, the present invention also provides a kind of device that car speed is measured based on single geomagnetic sensor, including：
Acquisition module：For obtaining geomagnetic field intensity in multiple cycles that geomagnetic sensor is gathered in real time；Geomagnetic sensor
For being arranged under road, depth is set to be set according to common knowledge, geomagnetic sensor is gathered in real time with the cycle T set
Geomagnetic field intensity and gather once, single-chip microcomputer from geomagnetic sensor read once；
First computing module：Geomagnetic field intensity rate of change is obtained for calculating；
Second computing module：For the earth magnetism field strength according to resulting geomagnetic field intensity rate of change, and measured in advance
The relation of rate of change and car speed is spent, car speed is calculated.
The device that car speed is measured based on single geomagnetic sensor of the present invention, acquisition module uses single geomagnetic sensor
Car speed is measured, the influence in earth's magnetic field is quantified using car speed, changed by geomagnetic field intensity
Rate and the relation of car speed obtain car speed, take full advantage of the rule of car speed magnetic fields over the ground, this
Method measurement car speed is all suitable for any vehicle, solves the problem of influence that different automobile types produce to earth's magnetic field is different.
The present invention reduces construction volume under geomagnetic sensor burial ground and to road only with single geomagnetic sensor
Destruction, construction cost is low.
Further, the device for measuring car speed based on single geomagnetic sensor also includes：
Judge module：For determining whether that vehicle passes through according to the geomagnetic field intensity of acquisition.
Further, judge module, is further used for：
The geomagnetic field intensity that the geomagnetic field intensity that current period is obtained is obtained with upper a cycle is compared, if exceeding
Given threshold, then regarded as vehicle process, otherwise, regards as no vehicle and passes through.Specifically, have vehicle from distant place traveling to
When near geomagnetic sensor, the geomagnetic field intensity that geomagnetic sensor is collected with the sampling period, which has, significantly to be strengthened, according to this
Feature, BnowFor the geomagnetic field intensity of the earth's magnetic field X-axis of geomagnetic sensor the last time collection, BpreFor data BnowUpper one week
The geomagnetic field intensity of the earth's magnetic field X-axis of phase, works as Bnow-BpreDuring ＞ Δ B, it is determined as that vehicle passes through near geomagnetic sensor, otherwise,
There is no vehicle process, wherein Δ B is to determine whether vehicle by the threshold value set by geomagnetic sensor, the setting of threshold size
Can specifically it be set according to noisy degree of prevailing circumstances etc., the size of threshold value does not influence the implementation of the present invention.
If passing through geomagnetic sensor without vehicle, then geomagnetic sensor continues to gather geomagnetic sensor with the sampling period
Neighbouring earth's magnetic field field strength and geomagnetic sensor often gather that a data monolithic is machine-readable to be taken once, and whether monitoring vehicle has in real time
Vehicle passes through.If having detected vehicle by near geomagnetic sensor, then the magnetic field strength date to earth's magnetic field X-axis is carried out
Below deeper into analysis.
It is preferred that, geomagnetic sensor is three axle geomagnetic sensors, and geomagnetic field intensity is the geomagnetic field intensity of X-axis, and earth magnetism is passed
The direction of the X-axis of sensor is parallel with direction of traffic, as shown in figure 3, geomagnetic sensor is buried below road with appropriate depth,
Component schematic diagram of the magnetic field intensity in X, Y, Z axis, it is assumed that total magnetic intensity be component in S, X, Y, Z axis be respectively X1,
Y1, Z1, then meetBecause the direction of X-axis is parallel with direction of traffic, the earth magnetism field data of X-axis is most
It is regular, it is preferred that the geomagnetic field intensity used in the present invention is the geomagnetic field intensity of X-axis；
Hereinafter a kind of computational methods of geomagnetic field intensity rate of change are calculated for specific first computing module：
Geomagnetic field intensity when judging to have the vehicle pass through is Bnow, make B1=Bnow, from obtaining BnowMoment, Bnow1For most
The new geomagnetic field intensity once gathered, Bpre1For data Bnow1A upper cycle collection geomagnetic field intensity, work as Bpre1-Bnow1>Δ
B1When, wherein, Δ B1For given threshold, B is made2=Bpre1, calculate from there is geomagnetic field intensity BnowStart to there is earth's magnetic field
Intensity Bpre1This period geomagnetic sensor has the geomagnetic field intensity number N of collection altogether, and the geomagnetic field intensity rate of change is：Wherein, BsFor the geomagnetic field intensity rate of change of geomagnetic sensor X-axis, T is the cycle that geomagnetic sensor is sampled.
If it is judged that there is vehicle to be used as the first of calculating rate of change by the geomagnetic field intensity for the point for then passing through vehicle
It is individual, i.e. Bnow, be tested with vehicle through when by meeting given threshold find out the earth's magnetic field X-axis that geomagnetic sensor is gathered
Maximum (the i.e. B of geomagnetic field intensity during this period of timepre1) as second point, subtracted with the geomagnetic field intensity value of second point
The geomagnetic field intensity value divided by this period for removing first point are exactly rate of change, herein, can pass through this period and count sampling
Count to calculate, be (N+1) T.There is vehicle to be opened when passing through it is worth noting that, the computation interval of above-mentioned computational methods is judgement
Begin to stop when there is maximum to the geomagnetic field intensity of the X-axis of certain a period of time, do not arrived for vehicle at the time of the maximum occurs
At the time of directly over up to geomagnetic sensor, therefore, it is desirable to according to the velocity interval of vehicle to be measured, given threshold Δ is rationally set
B1, Δ B1Setting can be according to the velocity interval of vehicle to be measured, and ensure the geomagnetic field intensity maximum B of X-axispre1Appear in car
Reach geomagnetic field intensity directly over before, carry out test of many times, obtain rational given threshold.This computational methods are being taken into account
While calculating simple, accurate rate is higher.
It is preferred that, in the second computing module, the geomagnetic field intensity rate of change B of measured in advancesWith car speed v relation
For：
V=aBs 3+bBs 2+cBs+d (2)
Wherein, a, b, c, d be constant a, b, c, d in constant, formula (2) determination method it is as follows：
Geomagnetic field intensity data under different vehicle speed v are gathered with the same cycle, X-axis is tried to achieve according to the first computing module
Geomagnetic field intensity rate of change Bs, obtain multigroup Bs- v data, using least square fitting curve, obtain constant a, b, c, d.
Applicant is by lot of experiments discovery, geomagnetic field intensity rate of change BsRelation with car speed v will not be because of car
Type is different, vehicle size is different and changes, as shown in Fig. 2 to test obtained Bs- v data and curves, transverse axis is vehicle speed
Degree, unit km/h, transverse axis is the change rate of magnetic density of geomagnetic sensor X-axis, using least square method to Bs- v data and curves
It is fitted, obtains a=5.35 × 10-6, b=-0.00226, c=0.6457, d=-16.94, that is to say, that using the present invention
Computational methods can shield different automobile types, the vehicle size difference different to geomagnetic field disturbance, only according to change of magnetic field strength
Rate can calculate car speed.
In the present invention, the cycle T that geomagnetic sensor gathers geomagnetic field intensity in real time is 5-20ms；Outside geomagnetic sensor
Portion is provided with sealed insulation device, and geomagnetic sensor can be prevented to be imbedded in underground and penetrated into by rainwater, of the invention based on single
The measurable 0-240km/h of method of Magnetic Sensor measurement car speed speed.
It is worth noting that, the periphery of geomagnetic sensor can set the electronic components such as circuit board, due to being passed by earth magnetism
Sensor measurement geomagnetic field intensity is known technology, herein to the internal structure and measuring principle of geomagnetic sensor, is repeated no more, can
Measured with reference to common knowledge.
Described above is the preferred embodiment of the present invention, it is noted that for those skilled in the art
For, on the premise of principle of the present invention is not departed from, some improvements and modifications can also be made, these improvements and modifications
It should be regarded as protection scope of the present invention.
Claims (10)
1. a kind of method that car speed is measured based on single geomagnetic sensor, it is characterised in that including：
Step 1：Obtain geomagnetic field intensity in multiple cycles that geomagnetic sensor is gathered in real time；The geomagnetic sensor is used to set
Under road；
Step 2：Calculating obtains geomagnetic field intensity rate of change；
Step 3：According to the geomagnetic field intensity rate of change and vehicle speed of resulting geomagnetic field intensity rate of change, and measured in advance
The relation of degree, calculates car speed.
2. the method according to claim 1 that car speed is measured based on single geomagnetic sensor, it is characterised in that the step
Also include step 11 between rapid 1 and step 2：
Step 11：Determine whether that vehicle passes through according to the geomagnetic field intensity of acquisition, if so, performing step 2, if nothing, perform step
Rapid 1.
3. the method according to claim 2 that car speed is measured based on single geomagnetic sensor, it is characterised in that the step
Rapid 11 are further：
The geomagnetic field intensity that the geomagnetic field intensity that current period is obtained was obtained with a upper cycle is compared, if more than setting threshold
Value, then regarded as vehicle process, performs step 2, otherwise, regards as no vehicle and passes through, performs step 1.
4. the method according to claim 1 that car speed is measured based on single geomagnetic sensor, it is characterised in that describedly
Magnetic Sensor is three axle geomagnetic sensors, and the geomagnetic field intensity is the geomagnetic field intensity of geomagnetic sensor X-axis, and the earth magnetism is passed
The direction of the X-axis of sensor is parallel with direction of traffic, and the step 2 includes：
Geomagnetic field intensity when judging to have the vehicle pass through is Bnow, make B1=Bnow, from obtaining BnowMoment, Bnow1For newest one
The geomagnetic field intensity of secondary collection, Bpre1For data Bnow1A upper cycle collection geomagnetic field intensity, work as Bpre1-Bnow1>ΔB1When,
Wherein, Δ B1For given threshold, B is made2=Bpre1, calculate from there is geomagnetic field intensity BnowStart to there is geomagnetic field intensity
Bpre1This period geomagnetic sensor has the geomagnetic field intensity number N of collection altogether, and the geomagnetic field intensity rate of change is：Wherein, BsFor the geomagnetic field intensity rate of change of geomagnetic sensor X-axis, T is the cycle that geomagnetic sensor is sampled.
5. the method according to claim 4 that car speed is measured based on single geomagnetic sensor, it is characterised in that the step
In rapid 3, the geomagnetic field intensity rate of change B of measured in advancesRelation with car speed v is：
V=aBs 3+bBs 2+cBs+d (1)
Wherein, a, b, c, d are constant；
Constant a, b, c, d determination method are as follows in formula (1)：
Geomagnetic field intensity data under different vehicle speed v are gathered with the same cycle, the earth magnetism of X-axis is tried to achieve according to the step 2
Field intensity rate of change Bs, obtain multigroup Bs- v data, using least square fitting curve, obtain constant a, b, c, d.
6. a kind of device that car speed is measured based on single geomagnetic sensor, it is characterised in that including：
Acquisition module：For obtaining geomagnetic field intensity in multiple cycles that geomagnetic sensor is gathered in real time；The geomagnetic sensor
For being arranged under road；
First computing module：Geomagnetic field intensity rate of change is obtained for calculating；
Second computing module：For being become according to resulting geomagnetic field intensity rate of change, and the geomagnetic field intensity of measured in advance
The relation of rate and car speed, calculates car speed.
7. the device according to claim 6 that car speed is measured based on single geomagnetic sensor, it is characterised in that the base
The device for measuring car speed in single geomagnetic sensor also includes：
Judge module：For determining whether that vehicle passes through according to the geomagnetic field intensity of acquisition.
8. the device according to claim 7 that car speed is measured based on single geomagnetic sensor, it is characterised in that described to sentence
Disconnected module, is further used for：
The geomagnetic field intensity that the geomagnetic field intensity that current period is obtained is obtained with upper a cycle is compared, if more than setting
Threshold value, then regarded as vehicle process, otherwise, regards as no vehicle and passes through.
9. the device according to claim 6 that car speed is measured based on single geomagnetic sensor, it is characterised in that describedly
Magnetic Sensor is three axle geomagnetic sensors, and the geomagnetic field intensity is the geomagnetic field intensity of geomagnetic sensor X-axis, and the earth magnetism is passed
The direction of the X-axis of sensor is parallel with direction of traffic, first computing module, is further used for：
Geomagnetic field intensity when judging to have the vehicle pass through is Bnow, make B1=Bnow, from obtaining BnowMoment, Bnow1For newest one
The geomagnetic field intensity of secondary collection, Bpre1For data Bnow1A upper cycle collection geomagnetic field intensity, work as Bpre1-Bnow1>ΔB1When,
Wherein, Δ B1For given threshold, B is made2=Bpre1, calculate from there is geomagnetic field intensity BnowStart to there is geomagnetic field intensity
Bpre1This period geomagnetic sensor has the geomagnetic field intensity number N of collection altogether, and the geomagnetic field intensity rate of change is：Wherein, BsFor the geomagnetic field intensity rate of change of geomagnetic sensor X-axis, T is the cycle that geomagnetic sensor is sampled.
10. the device according to claim 9 that car speed is measured based on single geomagnetic sensor, it is characterised in that described
In second computing module, geomagnetic field intensity rate of change B set in advancesRelation with car speed v is：
V=aBs 3+bBs 2+cBs+d (2)
Wherein, a, b, c, d be constant a, b, c, d in constant, formula (2) determination method it is as follows：
Geomagnetic field intensity data under different vehicle speed v are gathered with the same cycle, X-axis is tried to achieve according to first computing module
Geomagnetic field intensity rate of change Bs, obtain multigroup Bs- v data, using least square fitting curve, obtain constant a, b, c, d.
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