CN102426787B - Method and system for measuring speed of vehicle by using single magnetic induction strength sensor - Google Patents

Abstract

The invention discloses a method and a system for measuring a speed of a vehicle by using a single magnetic induction strength sensor. The method comprises the following steps of: a, acquiring the occupation time of a magnetic induction strength sensor, which is arranged on a lane, by each vehicle which passes through the lane in a time period; b, determining a vehicle flow type of the time period, wherein the vehicle flow type comprises a mixed vehicle flow type and a single vehicle flow type of large vehicles and small vehicles; and c, determining the average occupation time of vehicles of a certain type in the time period, and thus obtaining a vehicle passing speed of the lane in the time period by using the average length of the vehicles of the type and the average occupation time of the vehicles of the type. The invention has the advantages that: the speeds of the vehicles which pass through the lane can be obtained by using only one magnetic induction strength sensor; and construction quantity and cost are reduced.

Description

Adopt single magnetic induction density sensor to carry out the method and system of vehicle speed measuring

Technical field

The present invention relates to that the road traffic speed of a motor vehicle detects, monitoring technical field, specifically a kind ofly adopt single magnetic induction density sensor to carry out the method and system of vehicle speed measuring.

Background technology

Existing road transportation network overload improves an urgent demand that its operational efficiency is Transportation Development.The important steps such as control of traffic and road, assessment and planning must be carried out on the basis of grasping the existing road traffic.How the mass traffic information that produces of highly effective gathering modern city system is a challenging problem.Using electronic information technology to gather road traffic information is its basic means, has occurred telefault, video, the main technology of several classes of microwave (RTMS) in engineering practice in decades.But it is Shortcomings aspect vehicle speed measuring: the telefault maintenance cost that easily is damaged is high; The technology of processing based on video image is subjected to natural weather condition, installation site and road surface complexity effect large, and the velocity estimation precision is not high; RTMS is subject to shelter (as the isolation strip) impact, and the installation site affects it and detects performance, and the vehicle speed measurement performance is not good enough yet.Based on the vehicle detection technology customer service preferably of magnetic induction density sensor environmental suitability, can obtain higher real-time vehicle speed by lay former and later two magnetic induction density sensors in same track, but cost is higher, and needs broken road to bury underground, damage the road surface, great in constructing amount.

Because the defective that above-mentioned existing vehicle speed measuring method exists, the inventor, positive research and innovation is in addition carried out the method and system of vehicle speed measuring, the deficiency that exists to solve prior art to the single magnetic induction density sensor of the employing of founding a kind of novelty.

Summary of the invention

In order to solve the above-mentioned problems in the prior art, the invention provides and a kind ofly adopt single magnetic induction density sensor to carry out the method for vehicle speed measuring, the method only needs a magnetic induction density sensor can obtain speed through the vehicle in this track, has reduced construction volume and cost.

In order to solve the problems of the technologies described above, the present invention has adopted following technical scheme:

Adopt single magnetic induction density sensor to carry out the method for vehicle speed measuring, comprise the steps:

A. gather each vehicle of passing through on a time period inside lane to being arranged on the holding time of the magnetic induction density sensor on this track;

B. determine the wagon flow type of this time period, described wagon flow type comprises mixed flow type and the single wagon flow type of large car and compact car;

C. determine the average holding time of a certain type car of this time period, the average length by the type car and the average holding time of the type car obtain the vehicle Negotiation speed in this this track of time period.

Further, described wagon flow type is determined by following formula, t _max＞α t _minBe the mixed flow type, otherwise be single wagon flow type, wherein t _minBe the minimum holding time in this time period, t _maxBe the maximum holding time in this time period, α is the ratio of the average length of the average length of known large car and compact car.

Further, the ratio of the average length of the average length of described large car and compact car is 2.

Further, when the wagon flow type is the mixed flow type, utilize maximum variance between clusters to carry out cluster analysis and distinguish large car and compact car, utilize the average length of average holding time of compact car and known compact car to obtain the average speed of the vehicle in this track in this time period.

Further, take maximum between-cluster variance corresponding to holding time of magnetic induction density sensor as large car and the final segmentation threshold of compact car, the holding time to the magnetic induction density sensor that is not more than this segmentation threshold is the holding time of compact car.

Further, when the wagon flow type is single wagon flow type, determine whether compact car, compact car obtains the average speed of the vehicle in this track in this time period with the average holding time in the average length of known compact car and this time period in this way; During for compact car as not judging, obtain an average speed with the average length of known compact car and the average holding time in this time period, and the average speed of a upper time period of introducing, relatively whether the Euclidean distance of two average speeds is less than certain limit, if less than, the average speed that calculates is for the average speed of this time period, if be not less than, the average speed of an above time period is the average speed of this time period.

Another object of the present invention adopts single magnetic induction density sensor to carry out the system of vehicle speed measuring for providing a kind of, and system of the present invention only needs a magnetic induction density sensor can obtain speed through the vehicle in this track, has reduced construction volume and cost.

The technical scheme that realizes above-mentioned purpose is as follows:

Adopt single magnetic induction density sensor to carry out the system of vehicle speed measuring, comprising:

One magnetic induction density sensor is arranged on a track, is sent to microprocessor after gathering space magnetic induction density and converting thereof into electric signal;

Microprocessor, the electric signal that the magnetic induction density sensor is sent carries out digital/analog signal conversion and digital signal processing, the holding time of each vehicle that passes through in one time period of acquisition to described magnetic induction density sensor; Determine the wagon flow type of this time period, described wagon flow type comprises mixed flow type and the single wagon flow type of large car and compact car; Determine the average holding time of a certain type car of this time period, the average length by the type car and the average holding time of the type car obtain the vehicle Negotiation speed in this this track of time period.

Further, described wagon flow type is determined by following formula, t _max＞α t _minBe the mixed flow type, otherwise be single wagon flow type, wherein t _minBe the minimum holding time in this time period, t _maxBe the maximum holding time in this time period, α is the ratio of the average length of the average length of known large car and compact car.

Further, the ratio of the average length of the average length of described large car and compact car is 2.

Further, when the wagon flow type is the mixed flow type, utilize maximum variance between clusters to carry out cluster analysis and distinguish large car and compact car, utilize the average length of average holding time of compact car and known compact car to obtain the average speed of the vehicle in this track in this time period.

Further, take maximum between-cluster variance corresponding to holding time of magnetic induction density sensor as large car and the final segmentation threshold of compact car, the holding time to the magnetic induction density sensor that is not more than this segmentation threshold is the holding time of compact car.

Further, when the wagon flow type is single wagon flow type, determine whether compact car, compact car obtains the average speed of the vehicle in this track in this time period with the average holding time in the average length of known compact car and this time period in this way; During for compact car as not judging, obtain an average speed with the average length of known compact car and the average holding time in this time period, and the average speed of a upper time period of introducing, relatively whether the Euclidean distance of two average speeds is less than certain limit, if less than, the average speed that calculates is for the average speed of this time period, if be not less than, the average speed of an above time period is the average speed of this time period.

Compared with prior art, beneficial effect of the present invention is:

1 compares with existing two magnetic induction density sensor wagon flow Speed Detection Technologies, and the present invention only buries a magnetic induction density sensor underground in a track can realize the wagon flow velocity estimation, effectively reduces cost, has reduced the infringement of construction volume and road pavement;

2 compare with existing two magnetic induction density sensor wagon flow Speed Detection Technologies, magnetic induction density sensor in the present invention only need be operated under the holding time statistical model can obtain the wagon flow velocity information, dual sensor is by obtaining vehicle by the mistiming of two sensors, except the spacing acquisition speed of two sensors.single-sensor only can obtain vehicle by sensor the time holding time, two factors of the speed of a motor vehicle and vehicle commander determine holding time length simultaneously, the holding time of single unit vehicle is computing velocity directly, this patent only utilizes the holding time of the interior a plurality of vehicles of the collection set time length of a cycle sensor, by the feature of utilizing real road traffic flow vehicle to consist of, the holding time has been carried out the statistical signal processing, and adopt on this basis different speed of a motor vehicle computing method to realize the estimation to wagon flow speed, the method greatly reduces magnetic induction density sensor power consumption, extended magnetic induction density sensor serviceable life,

3 compare with traditional unicoil vehicle speed estimation method, and the present invention has effectively reduced the evaluated error of bringing because of the randomness of oversize vehicle number variation;

4 compare with traffic flow detection techniques such as videos with existing microwave, and the present invention has weatherproof advantage;

5, applied range of the present invention, the inventive method calculated amount and committed memory are all less, are adapted at realizing in Miniature magnetic induction sensor hardware, can be applicable to the various traffic flows such as road, expressway, bridge, tunnel and detect scene.

Description of drawings

Fig. 1 is the schematic flow sheet that the single magnetic induction density sensor of employing of the present invention carries out the method for vehicle speed measuring;

Fig. 2 is the work schematic diagram that the single magnetic induction density sensor of employing of the present invention carries out the system of vehicle speed measuring.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail, but not as a limitation of the invention.

Fig. 1 is the schematic flow sheet that the single magnetic induction density sensor of employing of the present invention carries out the method for vehicle speed measuring; As shown in Figure 1, the vehicle speed measuring method of single magnetic induction density sensor comprises the steps:

A. gather each vehicle of passing through on a time period inside lane to being arranged on the holding time of the magnetic induction density sensor on this track;

B. determine the wagon flow type of this time period, described wagon flow type comprises mixed flow type and the single wagon flow type of large car and compact car;

C. determine the average holding time of a certain type car of this time period, the average length by the type car and the average holding time of the type car obtain the vehicle Negotiation speed in this this track of time period.

Determining of wagon flow type:

The vehicle number being detected in one time period i is N (i), and the minimum holding time to the magnetic induction density sensor in N (i) car is t _min, the maximum holding time is t _max,

t _min＝min{t ₁，t ₂，…，t _N}

t _max＝max{t ₁，t ₂，…，t _N}

t ₁, t ₂..., t _NBe respectively N (i) car to the holding time of magnetic induction density sensor.If t _max＞α t _min, the wagon flow type is the mixed flow type, namely has simultaneously large car and compact car in wagon flow, if t _max≤ α t _min, the wagon flow type is single wagon flow type.α is the average length of known large car

Average length with compact car

Ratio.According to statistics, α is made as 2.0.According to the threshold value N of the vehicle number N (i) that passes through in this time period with the vehicle flowrate size judgement of setting _maxCompare, the vehicle flowrate that can judge in this time period is large or little.N (i)＞N _maxThe time, vehicle flowrate is large, as N (i)≤N _maxThe time, vehicle flowrate is little.Simultaneously, N _maxValue be to adopt mass data artificial and that the first-class monitored in various ways of shooting obtains to add up the empirical value that draws according to traffic department, the rule of value is: the quantity that occurs continuously and only occur oversize vehicle in given monitoring time in urban road is N _maxProbability extremely low, can think N not occur occurring continuously within given detection time _maxAnd the quantity that oversize vehicle only occurs is.According to N (i) and threshold value N _maxAnd t _maxAnd t _minRelation can be refined as the wagon flow type four types, and the detailed division of wagon flow type sees the following form 1.

Table 1

	N＞N max	N≤N max
			t max＞α·t min	Type 1.	Type 2.
t max≤α·t min	Type 3.	Type 4.

Wherein, 1. various and flow are large; 2. various and flow are little; 3. single vehicle and flow are large; 4. single vehicle and flow are little.

For the mixed flow type, namely the type in table 1 1. with type 2., in this time period average speed obtain with the average holding time of compact car and the average length of known compact car.

Work as t _max＞α t _minThe time, the wagon flow type is type in hybrid vehicle, namely by comprising simultaneously large car and compact car in vehicle.First utilize maximum variance between clusters to carry out cluster analysis to distinguish large car and compact car.Then utilize mean transit time and the known average vehicle commander of compact car to calculate average speed.Method is as follows:

Compact car and large car number are designated as respectively N _S(i) and N _L(i), N _S(i)+N _L(i)=N (i).

The ratio that compact car and large car is accounted for total vehicle number N (i) is designated as respectively ω _SAnd ω _L, ${\mathrm{\ω}}_S=\frac{N_S\left(i\right)}{N\left(i\right)},$ ${\mathrm{\ω}}_L=\frac{N_L\left(i\right)}{N\left(i\right)},$ ω _S+ω _L＝1。

In this time period, compact car and large car are designated as respectively the mean value of the holding time of magnetic induction density sensor

With

The overall average holding time of rolling stock is designated as u,

$u={\mathrm{\ω}}_S\·{\stackrel{\‾}{t}}_S\left(i\right)+{\mathrm{\ω}}_L\·{\stackrel{\‾}{t}}_L\left(i\right)---\left(1\right)$

, the holding time t of each car to the magnetic induction density sensor _j(i), j=1,2 ..., the corresponding inter-class variance g of N (i) _jFor

g _j＝ω _S(μ _S-u) ²+ω _L(μ _L-u) ² (2)

Formula (1) substitution formula (2) can be got:

$g_j={\mathrm{\ω}}_S{\mathrm{\ω}}_L{({\stackrel{\‾}{t}}_S\left(i\right)-{\stackrel{\‾}{t}}_L\left(i\right))}^2---\left(3\right)$

Again travel through in turn the value of j, obtain maximum between-cluster variance g _max,

g _max＝max{g ₁，g ₂，…，g _N}

With maximum between-cluster variance g _maxThe holding time t of corresponding vehicle to the magnetic induction density sensor _m(i) be designated as the final segmentation threshold of large car and compact car, that is:

$\∀t_j\left(i\right)\≤t_m\left(i\right),$ Judgement is compact car;

$\∀t_j\left(i\right)>t_m\left(i\right),$ Judgement is large car.

At last, according to the mean value of compact car to the holding time of magnetic induction density sensor

Average length with known compact car

Obtain the average speed of the vehicle in this track in this time period

${\stackrel{\‾}{t}}_S\left(i\right)=\frac{1}{N_S\left(i\right)}\underset{j=1}{\overset{N_S\left(i\right)}{\mathrm{\Σ}}}{t}_j\left(i\right)$

$\stackrel{\‾}{s}\left(i\right)=\frac{{\stackrel{\‾}{L}}_S}{{\stackrel{\‾}{t}}_S\left(i\right)}.$

For single wagon flow type

Work as t _max≤ α t _minThe time, the wagon flow type is single wagon flow type, namely only has compact car or only has large car, and possessing simultaneously N (i)＞N _maxThe time, be type 3., according to N _maxValue rule, can judge only to be compact car by vehicle this moment, at this moment, directly adopt the average length of known compact car With the mean value to holding time of magnetic induction density sensor of this time period, namely compact car calculates the average speed of this time period to the mean value of the holding time of magnetic induction density sensor, and formula is as follows:

$\stackrel{\‾}{t}\left(i\right)=\frac{1}{N\left(i\right)}\underset{j=1}{\overset{N\left(i\right)}{\mathrm{\Σ}}}{t}_j\left(i\right)$

$\stackrel{\‾}{s}\left(i\right)=\frac{{\stackrel{\‾}{L}}_S}{\stackrel{\‾}{t}\left(i\right)}.$

Work as t _max≤ α t _minAnd N (i)≤N _maxThe time, for type 4., the wagon flow vehicle is that single wagon flow type and vehicle flowrate are little.According to N _maxValue rule, this moment vehicle big or small uncertain, adopt this moment the method for memory judgement to obtain interior average speed of this time period, specific as follows:

Suppose that current N (i) car is compact car entirely, so just obtain the average speed in this time period with above-mentioned method

Namely use the average length of known compact car

With the mean value to holding time of magnetic induction density sensor of this time period, namely compact car calculates the average speed of this time period to the mean value of the holding time of magnetic induction density sensor.Introduce the average speed of a known upper time period i-1

When

With

Euclidean distance less than certain limit, hypothesis is set up so, namely all vehicles are compact car, with the result the calculated average speed as this time period; Otherwise judgement hypothesis is false, and namely all vehicles are large car, chooses the average speed of a time period this moment as the average speed of current time, that is:

$\left\{\begin{array}{cc}\stackrel{\‾}{s}\left(i\right)={\stackrel{\‾}{s}}^{\′}\left(i\right),& |{\stackrel{\‾}{s}}^{\′}\left(i\right)-\stackrel{\‾}{s}(i-1)|\≤\mathrm{\β}\·\stackrel{\‾}{s}(i-1)\\ \stackrel{\‾}{s}\left(i\right)=\stackrel{\‾}{s}(i-1),& |{\stackrel{\‾}{s}}^{\′}\left(i\right)-\stackrel{\‾}{s}(i-1)|>\mathrm{\β}\·\stackrel{\‾}{s}(i-1)\end{array}\right.---\left(4\right)$

In formula, β gets 0.10.The Euclidean distance of one dimension function i.e. the absolute value of 2 differences, The β that can not surpass previous time period for the difference of the hypothesis speed of current slot and previous time period speed doubly, the value of β is also the empirical value that goes out according to a large amount of statisticss.

Fig. 2 is the work schematic diagram that the single magnetic induction density sensor of employing of the present invention carries out the system of vehicle speed measuring.As shown in Figure 2, adopt single magnetic induction density sensor to carry out the system of vehicle speed measuring, comprise

One magnetic induction density sensor is arranged on a track, is sent to microprocessor after gathering space magnetic induction density and converting thereof into electric signal;

Microprocessor, the electric signal that the magnetic induction density sensor is sent carries out digital/analog signal conversion and digital signal processing, the holding time of each vehicle that passes through in one time period of acquisition to described magnetic induction density sensor; Determine the wagon flow type of this time period, described wagon flow type comprises mixed flow type and the single wagon flow type of large car and compact car; Determine the average holding time of a certain type car of this time period, the average length by the type car and the average holding time of the type car obtain the vehicle Negotiation speed in this this track of time period.In embodiment, the magnetic induction density sensor adopts HMC1052L type magnetic induction sensor, and microprocessor adopts MSP430F149 type production of integrated circuits.There are ALU (be used for carrying out and calculate), totalizer and general purpose register set (storage intermediate result) in its inside; Programmable counter, data and address latch/impact damper, internal bus (data interaction between each hardware), storer (storage program) etc.Each element in the vehicle speed measuring system of single magnetic induction density sensor of the present invention, does not repeat them here in conjunction with Fig. 2 and referring to the said method part the processing procedure of data.

Above embodiment is only exemplary embodiment of the present invention, is not used in restriction the present invention, and protection scope of the present invention is defined by the claims.Those skilled in the art can make various modifications or be equal to replacement the present invention in essence of the present invention and protection domain, this modification or be equal to replacement and also should be considered as dropping in protection scope of the present invention.

Claims (8)

1. adopt single magnetic induction density sensor to carry out the method for vehicle speed measuring, it is characterized in that, comprise the steps:

A. gather each vehicle of passing through on a time period inside lane to being arranged on the holding time of a magnetic induction density sensor on this track;

B. determine the wagon flow type of this time period, described wagon flow type comprises mixed flow type and the single wagon flow type of large car and compact car;

C. determine the average holding time of a certain type car of this time period, the average length by the type car and the average holding time of the type car obtain the vehicle Negotiation speed in this this track of time period; Wherein,

When the wagon flow type is single wagon flow type, determine whether compact car, compact car obtains the average speed of the vehicle in this track in this time period with the average holding time in the average length of known compact car and this time period in this way; During for compact car as not judging, obtain an average speed with the average length of known compact car and the average holding time in this time period, and the average speed of a upper time period of introducing, relatively whether the Euclidean distance of two average speeds is less than certain limit, if less than, the average speed that calculates is for the average speed of this time period, if be not less than, the average speed of an above time period is the average speed of this time period.

2. the single magnetic induction density sensor of employing according to claim 1 carries out the method for vehicle speed measuring, it is characterized in that, described wagon flow type is determined by following formula, t _maxα t _minBe the mixed flow type, otherwise be single wagon flow type, wherein t _minBe the minimum holding time in this time period, t _maxBe the maximum holding time in this time period, α is the ratio of the average length of the average length of known large car and compact car.

3. the single magnetic induction density sensor of employing according to claim 1 carries out the method for vehicle speed measuring, it is characterized in that, when the wagon flow type is the mixed flow type, utilize maximum variance between clusters to carry out cluster analysis and distinguish large car and compact car, utilize the average length of average holding time of compact car and known compact car to obtain the average speed of the vehicle in this track in this time period.

4. the single magnetic induction density sensor of employing according to claim 3 carries out the method for vehicle speed measuring, it is characterized in that, take maximum between-cluster variance corresponding to holding time of magnetic induction density sensor as large car and the final segmentation threshold of compact car, the holding time to the magnetic induction density sensor that is not more than this segmentation threshold is the holding time of compact car.

5. adopt single magnetic induction density sensor to carry out the system of vehicle speed measuring, it is characterized in that, comprising:

One magnetic induction density sensor is arranged on a track, is sent to microprocessor after gathering space magnetic induction density and converting thereof into electric signal;

Microprocessor, the electric signal that the magnetic induction density sensor is sent carries out digital/analog signal conversion and digital signal processing, the holding time of each vehicle that passes through in one time period of acquisition to described magnetic induction density sensor; Determine the wagon flow type of this time period, described wagon flow type comprises mixed flow type and the single wagon flow type of large car and compact car; Determine the average holding time of a certain type car of this time period, the average length by the type car and the average holding time of the type car obtain the vehicle Negotiation speed in this this track of time period; Wherein, when the wagon flow type is single wagon flow type, determine whether compact car, compact car obtains the average speed of the vehicle in this track in this time period with the average holding time in the average length of known compact car and this time period in this way; During for compact car as not judging, obtain an average speed with the average length of known compact car and the average holding time in this time period, and the average speed of a upper time period of introducing, relatively whether the Euclidean distance of two average speeds is less than certain limit, if less than, the average speed that calculates is for the average speed of this time period, if be not less than, the average speed of an above time period is the average speed of this time period.

6. the single magnetic induction density sensor of employing according to claim 5 carries out the system of vehicle speed measuring, it is characterized in that, described wagon flow type is determined by following formula, t _maxα t _minBe the mixed flow type, otherwise be single wagon flow type, wherein t _minBe the minimum holding time in this time period, t _maxBe the maximum holding time in this time period, α is the ratio of the average length of the average length of known large car and compact car.

7. the single magnetic induction density sensor of employing according to claim 5 carries out the system of vehicle speed measuring, it is characterized in that, when the wagon flow type is the mixed flow type, utilize maximum variance between clusters to carry out cluster analysis and distinguish large car and compact car, utilize the average length of average holding time of compact car and known compact car to obtain the average speed of the vehicle in this track in this time period.

8. the single magnetic induction density sensor of employing according to claim 7 carries out the system of vehicle speed measuring, it is characterized in that, take maximum between-cluster variance corresponding to holding time of magnetic induction density sensor as large car and the final segmentation threshold of compact car, the holding time to the magnetic induction density sensor that is not more than this segmentation threshold is the holding time of compact car.

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