CN102750824A - Urban road traffic condition detection method based on voting of network sorter - Google Patents

Abstract

The invention relates to an urban road traffic condition detection method based on the voting of a network sorter, which comprises the following steps: 1) monitoring traffic characteristic parameters in real time, and extracting the traffic characteristic parameters so as to obtain test sample sets, wherein the traffic characteristic parameters comprises average vehicle speed v(m/s), vehicle flow f(veh/s), time occupancy ratio s, and travel time t(s); 2) respectively carrying out classification by a SVM (support vector machine)classifier, a BP(beeper) neural network, and a SVM-BP (support vector machine-beeper) cascade classifier in the method of combining the voting of the SVM classifier, a BP neural network, and a SVM-BP cascade classifier; if the three categories are same, sorting the test samples into the category; or if two categories are same, comparing the sum of two weights of the same category with the weight of different categories so as to determine large weights as the classification results; or if the three categories are different, taking the results recognized by the classifiers with the highest weights as the results after the mergence. The urban road traffic condition detection method provided by the invention can efficiently enhance the accuracy.

Description

Urban road traffic state detection method based on multiple neural network classifier ballot

Technical field

The present invention relates to a kind of urban road traffic state detection method.

Background technology

The distinct issues the most that exist in the operation management of urban highway traffic are traffic congestion and traffic hazard.Through the traffic behavior detection algorithm is studied, can reduce the negative effect that traffic events brings road travel.Through to the fast detecting of traffic behavior and use means such as traffic flow is induced, traffic control; Can on the overall situation, reduce the traffic congestion harmful effect that network operation produces of satisfying the need to greatest extent; Avoid the expansion of congestion status, guarantee vehicle safety, cosily go.

The researcher has done some researchs to the traffic state judging of urban road and highway both at home and abroad.The automatic event detection algorithm that uses the earliest is California algorithm.This method is differentiated the burst traffic events that possibly exist through the occupation rate data that relatively more contiguous annular coil detecting device obtains.Li and McDonald have proposed a kind of freeway traffic event detection algorithm based on Floating Car.This algorithm is based on average stroke time and adjacent two period average stroke mistiming bivariate analysis models and design.Employings such as Shi Zhongke expansion Kalman filtering method is predicted highway traffic density.Wang GuoLins etc. use a kind of traffic behavior detection method towards panoramic video.The k nearest neighbor nonparametric Regression Model that Dou Huili etc. have proposed a kind of traffic behavior forecast is used for the different probability forecast experiments of forecasting the classification traffic behavior of duration of urban road.Pi Xiaoliang etc. adopt clustering method, have realized a kind of traffic behavior sorting technique based on the Information Monitoring of toroid winding detecting device.The occupation rate data that toroid winding collects on the analysis highway sections such as Zhuan Bin provide the automatic detection algorithm of average occupancy congested in traffic on the Urban road.

Summary of the invention

In order to overcome the relatively poor deficiency of accuracy of existing urban road traffic state detection method, the present invention provides a kind of urban road traffic state detection method based on multiple neural network classifier ballot of effective raising accuracy.

The technical solution adopted for the present invention to solve the technical problems is:

A kind of urban road traffic state detection method based on multiple neural network classifier ballot, said detection method may further comprise the steps:

1) the traffic characteristic parameter comprises vehicle average velocity v (m/s), vehicle flowrate f (veh/s), time occupancy s, journey time t (s), is defined as respectively

$v=\frac{{\mathrm{\Σ}}_{i=1}^{n_{\mathrm{\τ}}}{v}_i}{n_{\mathrm{\τ}}},i=\mathrm{1,2},...n_{\mathrm{\τ}}---\left(1\right)$

$f=\frac{n_{\mathrm{\τ}}}{\mathrm{\τ}},---\left(2\right)$

$s=\frac{t_2-{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="HDA00001784406600021.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}{\mathrm{\&tau;}},---\left(3\right)$

t=t ₂-t ₁， (4)

In the following formula, v _iBe the speed of a motor vehicle of each car through certain section, τ is the time interval of the collection data of setting, n _τFor passing through the gross vehicle number of this section, t in the time interval τ ₁For vehicle begins to get into moment in this setting highway section, t ₂Pass through the moment in this highway section fully for vehicle; Formula (1) is illustrated in the mean value of the speed of a motor vehicle that the inherent fixing observation place of designated time intervals records; The vehicle number that this highway section is passed through in formula (2) the representation unit time; Formula (3) expression vehicle is through the ratio that must account for Fixed Time Interval τ the time in this highway section, i.e. time occupation rate; Formula (4) has defined journey time; Journey time representes that vehicle passes through required T.T. of a certain highway section of road, comprises running time and delay time at stop.

The traffic characteristic of the traffic characteristic parameter in monitoring highway section, and extraction in real time parameter obtains the test sample book collection;

2) sorting technique that adopts SVM, BP, SVM-BP cascade classifier to merge mutually, specific as follows:

2.1) use SVM training function to train back and test set sample data to be imported into together in the svm classifier function respectively, detecting current traffic behavior, process is following:

(2.1.1) speed, flow, occupation rate, four input characteristic parameters of journey time are provided with weight; Promptly the big characteristic parameter speed of traffic behavior influence is amassed with data on flows multiplies each other; As a new input feature vector dimension; Make SVM training input parameter dimension be increased to 5 dimensions, again to the data normalization of traffic data sample set;

(2.1.2) utilize training set sample training svm classifier device after the normalization, utilize parameters C, γ after the thought of cross validation is found out optimization, obtain the traffic behavior sorter.Parameter γ is the radially γ parameter of base, two-layer perceptron (Sigmoid) kernel function of polynomial expression, Gauss.Parameters C is the punishment parameter that SVM is set, and the punishment parameters C is a nonnegative number;

(2.1.3) utilize test sample book collection data and the sorter that training obtains to test, judge to belong to unimpeded state, busy state or congestion status;

2.2) utilize BP neural net method training and test sample book Ji Ji tested:

(2.2.1) to the data normalization of test sample book collection;

(2.2.2) utilize training set sample training BP neural network classifier after the normalization, obtain the traffic behavior sorter; Said sorter is one three layers a feedforward network; Input layer has 4 nodes, 4 road traffic features of representative input, and latent layer has 12 nodes; Output layer has 3 nodes; Represent 3 kinds of traffic behavior types, promptly unimpeded state, busy state or congestion status, the activation function of latent layer and output layer adopts the Sigmoid function;

(2.2.3) utilize test set sample and the sorter that training obtains to test, judge to belong to unimpeded state, busy state and congestion status;

2.3) with the two-layer cascade classifier of test sample book collection input SVM-BP;

The two-layer cascade classifier of described SVM-BP comprises following processing procedure:

(2.3.1) utilization SVM training function trains back and test set sample data to be imported into together in the svm classifier function respectively, detects current traffic behavior, and process is following:

(2.3.1.1) speed, flow, occupation rate, four input characteristic parameters of journey time are provided with weight; Promptly the big characteristic parameter speed of traffic behavior influence is amassed with data on flows multiplies each other; As a new input feature vector dimension; Make SVM training input parameter dimension be increased to 5 dimensions, again to the data normalization of traffic data sample set;

(2.3.1.2) utilize training set sample training svm classifier device after the normalization, utilize parameters C, γ after the thought of cross validation is found out optimization, obtain the traffic behavior sorter.Parameter γ is the radially γ parameter of base, two-layer perceptron (Sigmoid) kernel function of polynomial expression, Gauss.Parameters C is the punishment parameter that SVM is set, and the punishment parameters C is a nonnegative number;

(2.3.1.3) utilize test sample book collection data and the sorter that training obtains to test, judge whether belong to unimpeded state, if judge that then current state is unimpeded state) if not, then get into 2.3.2;

(2.3.2) utilize BP neural net method training and test sample book Ji Ji tested:

(2.3.2.1) to the data normalization of test sample book collection;

(2.3.2.2) utilize training set sample training BP neural network classifier after the normalization, obtain the traffic behavior sorter; Said sorter is one three layers a feedforward network; Input layer has 4 nodes, 4 road traffic features of representative input, and latent layer has 12 nodes; Output layer has 2 nodes; Represent 2 kinds of traffic behavior types, i.e. busy state or congestion status, the activation function employing Sigmoid function of latent layer and output layer;

(2.3.2.3) utilize test set sample and the sorter that training obtains to test, judge to belong to busy state and congestion status;

2.4) if step 2.1), 2.2), 2.3) class categories identical, then should detect sample and be classified as this type of; If wherein 2 classifications are identical, so that classification is identical 2 weights sums and different classes of weights compare, to confirm that both bigger values are classification results; If 3 classifications are all inequality, the result that so that weights are the highest sorter is discerned is as the result after merging.

Further, said step (2.2.3) and (2.3.2.3) in, utilize time series, merge through classification results a plurality of continuous time points, obtain final differentiation result, detailed process is following:

A, employing svm classifier device or SVM-BP sorter are as the fundamental classifier of test;

B, initial n secondary data sample is classified and the record sort result, its result promptly differentiates the result and issues as final;

C, behind record n+1 secondary data sample classification result, adopt the ballot mode of integrated study, a preceding n+1 classification results is voted, draw a differentiation result, issue as the differentiation state of n+1 secondary data sample.

Technical conceive of the present invention is: for China urban express way traffic density is high, spacing is little, the speed of a motor vehicle is lower, the normal many operation conditionss in traffic congestion highway section of the property sent out; This paper has utilized SVM, BP meshsort algorithm to merge, and designs the sorting technique of a SVM, BP, SVM-BP cascade classifier ballot fusion.As the sample of training classifier, the weight of input characteristic parameter is set after utilizing the svm classifier device with the characteristic parameter pre-service of China's urban highway traffic, optimizes the SVM parameter, traffic behavior is classified out; Utilize the BP neural network that traffic behavior is classified out again; Then; Adopt the SVM-BP cascade classifier; As the sample of training classifier, the weight of input characteristic parameter is set after utilizing the svm classifier device with the characteristic parameter pre-service of China's urban highway traffic, optimizes the SVM parameter; Unimpeded state classification is come out, utilize the BP neural network again the non-classified busy and congestion status classification of ground floor sorter; To same test set sample,, then should detect sample and be classified as this type of if the class categories of 3 sorters is identical; If wherein 2 classifications are identical, so that classification is identical 2 weights sums and different classes of weights compare, to confirm that both bigger values are classification results; If 3 classifications are all inequality, the result that so that weights are the highest sorter is discerned is as the result after merging.This method can improve the city traffic detection accuracy effectively.

Beneficial effect of the present invention mainly shows: improve the city traffic detection accuracy effectively.

Description of drawings

Fig. 1 is the synoptic diagram of the structure of SVMs.

Fig. 2 is the topological structure synoptic diagram of BP neural network.

Fig. 3 is each characteristic parameter data profile of traffic data sample.

Embodiment

Below in conjunction with accompanying drawing the present invention is further described.

With reference to Fig. 1～Fig. 3, a kind of urban road traffic state detection method that merges SVM and BP neural network, the traffic characteristic parameter mainly comprises vehicle average velocity, vehicle flowrate, vehicle time occupancy etc.The method of DETECTION OF TRAFFIC PARAMETERS is a lot, mainly contains ultrasound examination, infrared detection, the detection of toroidal inductive circle, Computer Vision Detection.The ultrasound examination precision is not high, receives vehicle to block the influence with the pedestrian easily, the distance short (generally being no more than 12m) of detection.Infrared detection receives the influence of the thermal source of vehicle own, and is antimierophonic indifferent, and accuracy of detection is not high.The ring sensor accuracy of detection is high, but requires to be arranged in the civil structure of road surface, and road pavement has damage, construction and inconvenient installation, and also the quantity of installing is many.The continuous development of technology such as Computer Vision Detection Along with computer technology, Flame Image Process, artificial intelligence, pattern-recognition in recent years obtains application more and more widely in traffic flow detects.The data that the microwave data of the s Afforestation in Hangzhou City Zone main roads that the traffic parameter data of this problem provide from Hangzhou public transport department and video data and software VISSIM emulation obtain.

Characteristic parameter vehicle average velocity v (m/s), vehicle flowrate f (veh/s), time occupancy s, journey time t (s) are defined as

$v=\frac{{\mathrm{\&Sigma;}}_{i=1}^{n_{\mathrm{\&tau;}}}{v}_i}{n_{\mathrm{\&tau;}}},i=\mathrm{1,2},...n_{\mathrm{\&tau;}}---\left(5\right)$

$f=\frac{n_{\mathrm{\&tau;}}}{\mathrm{\&tau;}},---\left(6\right)$

$s=\frac{t_2-{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="HDA00001784406600021.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}{\mathrm{\&tau;}},---\left(7\right)$

t=t ₂-t ₁， (8)

In the following formula, v _iBe the speed of a motor vehicle of each car through certain section, τ is the time interval of the collection data of setting, n _τFor passing through the gross vehicle number of this section, t in the time interval τ ₁For vehicle begins to get into moment in this setting highway section, t ₂Pass through the moment in this highway section fully for vehicle.Formula (5) is illustrated in the mean value of the speed of a motor vehicle that the inherent fixing observation place of designated time intervals records.The vehicle number that this highway section is passed through in formula (6) the representation unit time.Formula (7) expression vehicle is through the ratio that must account for Fixed Time Interval τ the time in this highway section, i.e. time occupation rate.Formula (8) has defined journey time.Journey time representes that vehicle passes through required T.T. of a certain highway section of road, comprises running time and delay time at stop.

This paper is divided into Three Estate with road traffic state: unimpeded, busy, block up.Unimpeded service level is the highest.

1) unimpeded: this grade service level is in free flow and steady flow scope.Its height is limited to free flow, and each vehicle does not receive the influence of other vehicles in the traffic flow basically, has very high degree of freedom to select desired speed.Its lower bound will begin to notice in the traffic flow other users to his influence for each vehicle, but the degree of freedom of the speed of selection is also not too influenced.

2) busy: still in the steady flow scope, the interaction between vehicle becomes and becomes heavy this grade service level, and selection speed receives the restriction of other vehicles, and comfortable have obvious decline with convenience degree.

3) block up: excessively to unstable flow, speed all receives strict constraint with the driving degree of freedom to this grade service level, and is comfortable low with convenience degree, at signalized intersections very long queuing vehicle arranged by steady flow.When having a small amount of increase, the volume of traffic will go wrong aspect the operation.When the volume of traffic in certain highway section meets or exceeds the traffic capacity in this highway section, just can cause traffic jam.The phenomenon of stop-go appears in the operation in formation this moment, and they are extremely unstable.Vehicle has very long stop delay in the crossing, some vehicle even will wait two signal periods could pass through the crossing.

The acquisition of data is the modes that combine through the microwave data that utilizes the VISSIM of simulation software emulated data and stadium, Hangzhou road-phoenix to play road (north orientation south).

Stadium, the Hangzhou road-phoenix that provides according to Hangzhou traffic department plays the microwave data in road (north orientation south), utilizes the VISSIM software emulation traffic of this each period of crossing whole day, obtains 3170 in traffic data sample altogether.Data simulation used herein the data of traffic behavior of each period of whole day.Though classification accuracy does not have the said method of other documents high, they are strong to promote the ability force rate.Wherein the training set sample is 1730, and its classification number unimpeded, busy, that block up is respectively 878,669,183.1440 in test set sample, its classification number unimpeded, busy, that block up is respectively 740,565,135.Each characteristic parameter DATA DISTRIBUTION of traffic data sample is as shown in Figure 3.

In the present embodiment, the main thought of SVM is to set up a classification lineoid as the decision-making curved surface, makes that the isolation edge between positive example and the counter-example is maximized.The theoretical foundation of SVM is Statistical Learning Theory, is the approximate realization of structural risk minimization.This principle is based on the fact: the error rate (extensive error rate) on the study machine test data is the boundary with training error rate and an item sum that depends on Vapnik-Chervonenkis (VC) dimension; But under the merotype situation, SVMs is zero for last value, and makes second to minimize.

At support vector x _iAnd this notion of inner product nuclear between the vector x of input control extraction is the key of structure SVMs learning algorithm.The support vector collection is to be made up of the little subclass that algorithm extracts from training data.

The structure of SVMs is as shown in Figure 1.Among Fig. 1, k () is a kernel function, and its kind mainly contains:

1) linear kernel function: k (x, x _i)=x ^Tx _i;

2) polynomial kernel function: k (x, x _i)=(γ x ^Tx _i+ r) ^p, γ>0;

3) the radially basic kernel function of RBF: k (x, x _i)=exp (γ || x-x _i|| ²), γ>0;

4) the two-layer perceptron kernel function of Sigmoid: k (x, x _i)=tanh (γ x ^Tx _i+ r).

SVM is converted into a convex quadratic programming problem based on structural risk minimization with whole solution procedure, and it separates global optimum and unique.

Cross validation (Cross Validation) is a kind of statistical analysis technique of checking sorter performance.Its basic thought is under certain meaning, raw data to be divided into groups, and a part is as training set, and another part is as the checking collection.At first sorter is trained, utilize the checking collection to test the model that training obtains again, with these performance index as the evaluation sorter with training set.

The BP neural network is current application one of neural network model the most widely.It is a kind of Multi-layered Feedforward Networks, and it is trained by the error Back-Propagation algorithm.A large amount of input and output mode mapping relations can learnt and store to the BP network.Its learning rules are to use method of steepest descent, come the constantly weights and the threshold value of adjustment network through backpropagation, make the error sum of squares of network minimum.BP neural network model topological structure comprises input layer, latent layer and output layer.

The BP network is the counterpropagation network that non-linear differentiable function is carried out the weights training, and the BP algorithm belongs to the δ algorithm, is a kind of learning algorithm of supervised, and main thought is: for q input learning sample: x ₁, x ₂..., x _q, known its corresponding output sample is y ₁, y ₂..., y _qUtilize the actual output of network and the error between the target vector to revise its weights, make the square-error of network output layer reach minimum.The BP neural network topology structure is as shown in Figure 2.

Experiment shows that this method improves to classification accuracy.Experimental procedure is following:

1) generate the svm classifier device:

Utilize LIBSVM sorter training and test sample book collection (this paper adopts the LIBSVM tool box to accomplish parameter optimization, model training and result's test): the status flag of vehicle average velocity, vehicle flowrate, vehicle time occupancy, journey time characteristic and the judgement of the traffic characteristic parameter of extracting is carried out pre-service; Utilization SVM training function trains back and test set sample data to be imported into together in the svm classifier function respectively, and to detect current traffic behavior be unimpeded, busy or block up.

(1.1) speed, flow, occupation rate, four input characteristic parameters of journey time are provided with weight.

Promptly to big characteristic parameter speed of traffic behavior influence and data on flows multiply each other long-pending, vf as a new input feature vector dimension, makes SVM training input parameter dimension be increased to 5 and ties up.Again to the data normalization of traffic data sample set.

Utilize the training set sample training svm classifier device after the normalization, utilize parameters C, γ after the thought of cross validation is found out optimization, obtain the traffic behavior sorter.Parameter γ is the radially γ parameter of base, two-layer perceptron (Sigmoid) kernel function of polynomial expression, Gauss.Parameters C is the punishment parameter that SVM is set.The punishment parameters C is a nonnegative number, and its size is represented the size to the attention degree of the outlier in the training set sample.

Different SVM models, different kernel functions and parameter thereof all affect the performance index of algorithm.This paper takes 4 kinds of SVM models: linearity, polynomial expression, Gauss radially base, Sigmoid kernel function analyze.Adopt the thought of cross validation to carry out parameter optimization to different SVM model and kernel functions.Test repeatedly through getting different parameter areas, finally obtain one group of optimum parameter of classifying quality.

(1.2) utilize test set data and the sorter that training obtains to test.

2) generate the BP sorter:

(2.1) to the data normalization of traffic data sample set.

(2.2) utilize training set sample training BP neural network classifier after the normalization, obtain the traffic behavior sorter.

The network classifier of this paper design is one three layers a feedforward network.Input layer has 4 nodes, 4 road traffic features of representative input.Latent layer has 12 nodes.Output layer has 3 nodes, represents 3 kinds of traffic behavior types.The activation function of latent layer and output layer adopts the Sigmoid function.

(2.3) utilize test set sample and the sorter that training obtains to test.

The BP neural network has good performance in pattern recognition classifier.Three layers of BP network with unlimited hidden node can be realized arbitrarily from being input to the Nonlinear Mapping of output.

3) generate the SVM-BP sorter:

(3.1) at first training generates SVM, BP two sorters.Wherein svm classifier is unimpeded and non-unimpeded, and BP classifies busy and blocks up.

(3.2) utilize the svm classifier device with unimpeded the separating in the test set sample.

(3.3) ground floor is not detected the BP network classifier classification that the busy and test set sample that block up of classifying carries out the second layer.

In the present embodiment; The fusion of SVM-BP is that the advantage of svm classifier device and BP network classifier is merged, separately the classification shortcoming of forgoing, the rate of accuracy reached to 87.0833% of this two layers of classified device; Higher 2 percentage points than SVM (Gauss is base radially) sorter, higher 7 percentage points than BP network classifier.Therefore, all more superior on classifying quality than single S VM or BP meshsort algorithm based on SVM with the two layers of classified device of BP.

4) three sorter ballots are merged

If 1), 2), 3) in the sorter class categories identical, then should detect sample and be classified as this type of; If wherein 2 classifications are identical, so that classification is identical 2 weights sums and different classes of weights compare, to confirm that both bigger values are classification results; If 3 classifications are all inequality, the result that so that weights are the highest sorter is discerned is as the result after merging.

In the present embodiment, utilize the svm classifier device with the characteristic parameter pre-service of China's urban highway traffic after as the sample of training classifier, the weight of input characteristic parameter is set, optimize the SVM parameter, traffic behavior is classified out; Utilize the BP neural network that traffic behavior is classified out again; Then; Adopt the SVM-BP cascade classifier; As the sample of training classifier, the weight of input characteristic parameter is set after utilizing the svm classifier device with the characteristic parameter pre-service of China's urban highway traffic, optimizes the SVM parameter; Unimpeded state classification is come out, utilize the BP neural network again the non-classified busy and congestion status classification of ground floor sorter; To same test set sample,, then should detect sample and be classified as this type of if the class categories of 3 sorters is identical; If wherein 2 classifications are identical, so that classification is identical 2 weights sums and different classes of weights compare, to confirm that both bigger values are classification results; If 3 classifications are all inequality, the result that so that weights are the highest sorter is discerned is as the result after merging.

Simulation result is seen table 1.

Table 1

In the present embodiment, the implementation phase of to detection, can utilize time series, merge, obtain final differentiation result through classification results to a plurality of continuous time points.

The issuing time of supposing urban road traffic state is spaced apart 1 minute, data sample of per 1 minute record.The blending algorithm step is following:

(1) sorter after employing SVM (Gauss is base radially), SVM-BP or aforementioned any fusion is as the fundamental classifier of test.

(2) 4 initial 4 minutes moment data are classified and the record sort result, its result promptly issues as final differentiation result.

(3) behind the 5th minute classification results of record, adopt the ballot mode of integrated study, preceding 5 classification results are voted, draw one and differentiate the result, issue as the 5th minute differentiation state.

(4) from the 6th minute, when m minute (m>5), behind its classification results of record, to m-4, m-3, m-2, m-1, m minute 5 classification results constantly vote or based on the fusion of integrated study.Draw one and differentiate the result, as m minute issue result.

Because in the reality, possibly there is error in the data collection task of urban highway traffic characteristic parameter.The sorter classification accuracy that uses can not reach 100%.This blending algorithm can reduce effectively because the correlation noise that data are inaccurate and error in classification causes that data acquisition causes improves the accuracy of differentiating traffic behavior greatly.Avoided the single erroneous judgement directly to issue the confusion that causes simultaneously.

Claims (2)

1. urban road traffic state detection method based on the ballot of multiple neural network classifier, it is characterized in that: said detection method may further comprise the steps:

1) the traffic characteristic parameter comprises vehicle average velocity v (m/s), vehicle flowrate f (veh/s), time occupancy s, journey time t (s), is defined as respectively

$v=\frac{{\mathrm{\&Sigma;}}_{i=1}^{n_{\mathrm{\&tau;}}}{v}_i}{n_{\mathrm{\&tau;}}},i=\mathrm{1,2},...n_{\mathrm{\&tau;}},---\left(1\right)$

$f=\frac{n_{\mathrm{\&tau;}}}{\mathrm{\&tau;}},---\left(2\right)$

$s=\frac{t_2-t_1}{\mathrm{\&tau;}},---\left(3\right)$

t=t ₂-t ₁， (4)

In the following formula, v _iBe the speed of a motor vehicle of each car through certain section, τ is the time interval of the collection data of setting, n _τFor passing through the gross vehicle number of this section, t in the time interval τ ₁For vehicle begins to get into moment in this setting highway section, t ₂Pass through the moment in this highway section fully for vehicle; Formula (1) is illustrated in the mean value of the speed of a motor vehicle that the inherent fixing observation place of designated time intervals records; The vehicle number that this highway section is passed through in formula (2) the representation unit time; Formula (3) expression vehicle is through the ratio that must account for Fixed Time Interval τ the time in this highway section, i.e. time occupation rate; Formula (4) has defined journey time; Journey time representes that vehicle passes through required T.T. of a certain highway section of road, comprises running time and delay time at stop;

The traffic characteristic of the traffic characteristic parameter in monitoring highway section, and extraction in real time parameter obtains the test sample book collection;

2) sorting technique that adopts SVM, BP, SVM-BP cascade classifier to merge mutually, specific as follows:

2.1) use SVM training function to train back and test set sample data to be imported into together in the svm classifier function respectively, detecting current traffic behavior, process is following:

(2.1.1) speed, flow, occupation rate, four input characteristic parameters of journey time are provided with weight; Promptly the big characteristic parameter speed of traffic behavior influence is amassed with data on flows multiplies each other; As a new input feature vector dimension; Make SVM training input parameter dimension be increased to 5 dimensions, again to the data normalization of traffic data sample set;

(2.1.2) utilize training set sample training svm classifier device after the normalization, utilize parameters C, γ after the thought of cross validation is found out optimization, obtain the traffic behavior sorter.Parameter γ is the radially γ parameter of base, two-layer perceptron (Sigmoid) kernel function of polynomial expression, Gauss.Parameters C is the punishment parameter that SVM is set, and the punishment parameters C is a nonnegative number;

(2.1.3) utilize test sample book collection data and the sorter that training obtains to test, judge to belong to unimpeded state, busy state or congestion status;

2.2) utilize BP neural net method training and test sample book Ji Ji tested:

(2.2.1) to the data normalization of test sample book collection;

(2.2.2) utilize training set sample training BP neural network classifier after the normalization, obtain the traffic behavior sorter; Said sorter is one three layers a feedforward network; Input layer has 4 nodes, 4 road traffic features of representative input, and latent layer has 12 nodes; Output layer has 3 nodes; Represent 3 kinds of traffic behavior types, promptly unimpeded state, busy state or congestion status, the activation function of latent layer and output layer adopts the Sigmoid function;

(2.2.3) utilize test set sample and the sorter that training obtains to test, judge to belong to unimpeded state, busy state and congestion status;

2.3) with the two-layer cascade classifier of test sample book collection input SVM-BP;

The two-layer cascade classifier of described SVM-BP comprises following processing procedure:

(2.3.1) utilization SVM training function trains back and test set sample data to be imported into together in the svm classifier function respectively, detects current traffic behavior, and process is following:

(2.3.1.1) speed, flow, occupation rate, four input characteristic parameters of journey time are provided with weight; Promptly the big characteristic parameter speed of traffic behavior influence is amassed with data on flows multiplies each other; As a new input feature vector dimension; Make SVM training input parameter dimension be increased to 5 dimensions, again to the data normalization of traffic data sample set;

(2.3.1.2) utilize training set sample training svm classifier device after the normalization; Utilize parameters C, γ after the thought of cross validation is found out optimization; Obtain the traffic behavior sorter; Parameter γ is the radially γ parameter of base, two-layer perceptron (Sigmoid) kernel function of polynomial expression, Gauss, and parameters C is the punishment parameter that SVM is set, and the punishment parameters C is a nonnegative number;

(2.3.1.3) utilize test sample book collection data and the sorter that training obtains to test, judge whether belong to unimpeded state, if judge that then current state is unimpeded state) if not, then get into 2.3.2;

(2.3.2) utilize BP neural net method training and test sample book Ji Ji tested:

(2.3.2.1) to the data normalization of test sample book collection;

(2.3.2.2) utilize training set sample training BP neural network classifier after the normalization, obtain the traffic behavior branch

The class device; Said sorter is one three layers a feedforward network; Input layer has 4 nodes, 4 road traffic features of representative input, and latent layer has 12 nodes; Output layer has 2 nodes; Represent 2 kinds of traffic behavior types, i.e. busy state or congestion status, the activation function employing Sigmoid function of latent layer and output layer;

(2.3.2.3) utilize test set sample and the sorter that training obtains to test, judge to belong to busy state and congestion status;

2.4) if step 2.1), 2.2), 2.3) class categories identical, then should detect sample and be classified as this type of; If wherein 2 classifications are identical, so that classification is identical 2 weights sums and different classes of weights compare, to confirm that both bigger values are classification results; If 3 classifications are all inequality, the result that so that weights are the highest sorter is discerned is as the result after merging.

2. the urban road traffic state detection method based on multiple neural network classifier ballot as claimed in claim 1; It is characterized in that: said step (2.2.3) and (2.3.2.3) in; Utilize time series; Classification results through to a plurality of continuous time points merges, and obtains final differentiation result, and detailed process is following:

A, employing svm classifier device or SVM-BP sorter are as the fundamental classifier of test;

B, initial n secondary data sample is classified and the record sort result, its result promptly differentiates the result and issues as final;

C, behind record n+1 secondary data sample classification result, adopt the ballot mode of integrated study, a preceding n+1 classification results is voted, draw a differentiation result, issue as the differentiation state of n+1 secondary data sample.

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