CN105894809A - Sectional type urban road traffic state estimation method - Google Patents

Abstract

The invention belongs to the intelligent transportation technical field and relates to a sectional type urban road traffic state estimation method. The method of the invention includes the following steps that: (1) traffic flow detectors are located in different locations in a whole road section, and the whole road section is divided into three sub road sections, namely, an upstream road section, a midstream road section and a downstream road section; (2) the speeds of the sub road sections are calculated through using a speed-flow polynomial traffic flow model; (3) the average speed of the whole road section is calculated according to the speeds of the sub road sections; (4) the traffic state of the road is calculated according to the average speed of the whole road section; and (5) the calculation model can be extended according to the change of the number of the traffic flow detectors. With the sectional type urban road traffic state estimation method provided by the technical schemes of the invention adopted, the problem of ambiguity in a speed-flow conversion process can be solved, and the accuracy and reliability of road traffic state prediction can be effectively improved.

Description

A kind of stagewise urban road traffic state method of estimation

Technical field

The present invention relates to technical field of intelligent traffic, be specifically related to a kind of stagewise urban road traffic state and estimate Meter method.

Background technology

Urban highway traffic faces the series of challenges such as traffic safety, traffic congestion, traffic pollution, traffic pipe The attention rate of urban transportation running status is continued to increase by reason department and the public.Generally, put down according to section All speed weighs road traffic state.At present, each city be generally mounted with on road coil, microwave and Polytype Traffic flow detecting device such as bayonet socket, additionally disposes vehicle GPS on a large amount of buses, taxi To obtain traffic flow data.Vehicle flowrate can accurately be measured substantially by above Traffic flow detecting device, but wants Think to change into road average speed exactly, then need to rely on speed-flow traffic flow model suitably.

To in the research of speed-flow traffic flow model and practice process, the inventors found that: In the conversion process of speed and flow, there is certain ambiguity, it directly affects road average speed and estimates The accuracy of meter.Such as sensor detects when flow is less, and road average speed may be very fast, because logical The vehicle crossed is the most sparse, and speed is very fast, but negligible amounts；Meanwhile, road average speed is likely to relatively slow, Because speed result in the negligible amounts that vehicle passes through more slowly.But, this phenomenon at the diverse location in section, But there is different performances.Such as, when entrance wagon flow is less, it is speed situation faster mostly；Outlet car When flowing less, it is the slower situation of speed mostly；In the middle part of road and entrance wagon flow the most less, then speed is fast Probability is the highest.This explanation turns in view of the positional information of sensor, the speed flowrate of segmentation diverse location Change parameter, be favorably improved the accuracy of speed and traffic transformation.Therefore, urban road traffic state is carried out During prediction, it is necessary to take into account speed that in section, position difference causes and the difference of flow corresponding relation.

Summary of the invention

Estimate toggle speed and the ambiguity problem of traffic transformation existence for traffic behavior, the invention provides one Plant stagewise urban road traffic state method of estimation.Described technical scheme is as follows:

A kind of stagewise urban road traffic state method of estimation, described method includes:

Step 1:

According to system-wide section is fixed the diverse location residing for Traffic flow detecting device, system-wide section is divided into 3 sons Section, wherein one section near section entrance is referred to as section, upstream, and a section exported near section is referred to as Downstream road section, remaining one section is referred to as section, middle reaches.

Step 2:

For the section, upstream described in step 1, section, middle reaches, downstream road section, by fixed pattern in each section Flow that Traffic flow detecting device observes, speed historical data, use Least Square Method to obtain traffic flow Model parameter a, b, c and d, it may be assumed that

U=a-(b × q-c)^d (1)

In formula, by the flow in certain section in the q representation unit time.

Step 3:

Section segmentation according to step 1 and the calculated model parameter of step 2, use diverse location traffic The average passage rate of the flow rate calculation correspondence position of current sensor actual measurement, its formula is:

u_l=a-(b × q_l-c)^d (2)

In formula, l represents that speed and flow are all the results observed when distance crossing l.

Step 4:

Passage rate meter according to diverse location in system-wide section calculated in step 3 (or different segmentation) Calculate the average passage rate of system-wide section, it may be assumed that

$u=\left({\∫}_0^L{u}_l\mathrm{dl}\right)/L---\left(3\right)$

In formula, L represents road section length.Formula (2) is substituted into formula (3), obtains:

$u=\left({\∫}_0^L\right[a-{(b\×q_l-c)}^d\left]\mathrm{dl}\right)/L---\left(4\right)$

In formula, u is i.e. for the calculated full road-section average of traffic flow observed according to diverse location in section Speed.

In actual applications, owing to the speed flowrate situation of change of each position on section, formula can not be obtained (4) can be reduced to:

$u={\mathrm{\Σ}}_{l=1}^{l=L}{\∂}_l(a-{(b\×q_l-c)}^d)/L---\left(5\right)$

In formula,For each segmentation Traffic flow detecting device weight to calculating Road average-speed.Can use true Real data automatic Fitting method of estimation obtains.

Step 5:

Set up the transfer equation of flow-speed-state, the road average speed in formula (5) is mapped to state The result in territory, mapping function is DSS, it may be assumed that

$S={\mathrm{\Σ}}_{l=1}^{l=L}{\∂}_l\mathrm{DSS}(a-{(b\×q_l-c)}^d)/L---\left(6\right)$

In formula, S represents the traffic behavior of road,Represent that each Traffic flow detecting device is to calculating road traffic state Weight.

When section newly increases during (or minimizing) n Traffic flow detecting device, need to formula (6) increase (or Reduce) the speed-flow transformation result of Traffic flow detecting device overlay segments, it may be assumed that

$u={\mathrm{\Σ}}_{l=1}^{l=L\±n}{\∂}_l\mathrm{DSS}(a-{(b\×q_l-c)}^d)/(L\±n)---\left(7\right)$

Having the beneficial effects that of the technical scheme that the embodiment of the present invention provides: by the friendship of diverse location in section Exploration section is divided by through-flow detector, calculates Ge Zi road respectively further according to the traffic flow observed Section average speed, finally the traffic to each segmentation accumulates the road traffic shape being calculated system-wide section Condition, so can overcome ambiguity problem present in speed and traffic transformation process, thus improve road and hand over The accuracy of logical status predication and reliability.

Accompanying drawing explanation

For the technical scheme being illustrated more clearly that in the embodiment of the present invention, institute in embodiment being described below The accompanying drawing used is needed to be briefly described, it should be apparent that, the accompanying drawing Fig. 2 in describing below is only this Some embodiments of invention, for those of ordinary skill in the art, before not paying creative work Put, it is also possible to obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is the calculation flow chart of the traffic state estimation method of the present invention.

Fig. 2 is the schematic diagram of one embodiment of the present of invention.

Detailed description of the invention

Below in conjunction with the accompanying drawing Fig. 2 in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out Clearly and completely describe, it is clear that described embodiment is only a part of embodiment of the present invention, and not It it is whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art are not making wound The all other embodiments obtained under the property made work premise, broadly fall into the scope of protection of the invention.

Section, Hangzhou shown in Fig. 2, this section is mounted with high definition bayonet socket 1, microwave 2 and ground induction coil 3 Three class Traffic flow detecting devices, wherein bayonet socket 1 is arranged on the entrance in section, and microwave 2 is arranged in section Near portion, ground induction coil 3 is arranged on the near exit in section.Record within a cycle by high definition card The vehicle flowrate in mouth 1, microwave 2 and installation site region, ground induction coil 3 place is q_b、q_w、q_c。

Step 1:

According to system-wide section is fixed the diverse location residing for Traffic flow detecting device, system-wide section is divided into upstream road Section, section, middle reaches and 3 sub-sections of downstream road section.

Step 2:

Multinomial model is used to describe speed when traffic flow in urban road is in stationary flow and blocks the stream stage Degree and discharge relation, its primitive form is:

U=a-(b × q-c)^d (8)

In formula, by the flow in certain section in the q representation unit time, u represents the flat of this period this section interior All passage rates.Owing to the fixed pattern Traffic flow detecting devices such as high definition bayonet socket 1, microwave 2 and ground induction coil 3 are entirely In section, present position is it is known that initially with the parameter initialization model of similar road, then use fixing Type Traffic flow detecting device place observation station history vehicle flow and speed data carry out parameter adjustment, finally give The model parameter in this section is a=66.1, b=-4.5e-2, c=1.6 and d=0.2.

Step 3:

The diverse locations such as section, upstream high definition bayonet socket 1, section, middle reaches microwave 2 and downstream road section ground induction coil 3 Average passage rate can be obtained by the flow rate calculation measured by the Traffic flow detecting device of relevant position:

$\left\{\begin{array}{c}{u}_b=a-{(b\×q_b-c)}^d\\ u_w=a-{(b\×q_w-c)}^d\\ u_c=a-{(b\×q_c-c)}^d\end{array}\right.---\left(9\right)$

In formula, q_i、u_i(i=b, w, c) represents high definition bayonet socket 1, microwave 2 and ground induction coil 3 position respectively Speed that place observes and flow.

Step 4:

The average passage rate of system-wide section can be by residing for high definition bayonet socket 1 in this section, microwave 2 and ground induction coil 3 The passage rate of position determines, in other words this section ensemble average passage rate is the knot that each segmentation is integrated Really, it may be assumed that

$u=\left({\∫}_0^L{u}_l\mathrm{dl}\right)/L---\left(10\right)$

In formula, L represents road section length.In order to represent local flow and the corresponding relation of road average speed, will Formula (9) substitutes into formula (10), obtains:

$u=\left({\∫}_0^L\right[a-{(b\×q_l-c)}^d\left]\mathrm{dl}\right)/L---\left(11\right)$

In formula, the Road average-speed that u i.e. calculates for the traffic flow observed according to diverse location in section.

Formula (11) exists integral and calculating process, i.e. it is to be appreciated that the road traffic condition of each segmentation.? In actual application, it is impossible to obtain the speed flowrate situation of change of each position on section.Therefore, model can To be reduced to:

$u={\mathrm{\Σ}}_{l=1}^{l=3}{\∂}_l(a-{(b\×q_l-c)}^d)/3---\left(12\right)$

In formula,For each position Traffic flow detecting device weight to calculating Road average-speed.Can use true Real data automatic Fitting method of estimation obtains.

Step 5:

Set up the transfer equation of flow-speed-state, the road average speed in formula (12) is mapped to shape The result in state territory, mapping function is DSS, it may be assumed that

$S={\mathrm{\Σ}}_{l=1}^{l=3}{\∂}_l\mathrm{DSS}(a-{(b\×q_l-c)}^d)/3---\left(13\right)$

In formula, S represents the traffic behavior of road,Represent that each Traffic flow detecting device is to calculating road traffic state Weight.

When section newly increases (or minimizing) n Traffic flow detecting device, need model to be adjusted, i.e. The speed flowrate transformation result of increase and decrease sensor overlay segments.Such as, a newly-increased GPS Floating Car in road I.e. think a newly-increased Traffic flow detecting device.GPS Floating Car may travel in any position in section, therefore may be used To gather the traffic data of multiple segmentations on section.As in figure 2 it is shown, newly-increased 3 taxis loading GPS Floating Car 4, Floating Car 5, Floating Car 6, i.e. increase the section that l=4,5,6 represent that gps data covers newly, then Formula after simplification can be expressed as:

$u={\mathrm{\Σ}}_{l=1}^{l=6}{\∂}_l\mathrm{DSS}(a-{(b\×q_l-c)}^d)/6---\left(14\right)$

A kind of stagewise urban road traffic state method of estimation provided the embodiment of the present invention above is carried out Being discussed in detail, principle and the embodiment of the present invention are set forth by specific case used herein, The explanation of above example is only intended to help to understand method and the core concept thereof of the present invention；Simultaneously for One of ordinary skill in the art, according to the thought of the present invention, the most all Will change, in sum, this specification content should not be construed as limitation of the present invention.

Claims (2)

1. a stagewise urban road traffic state method of estimation, it is characterised in that including:

Step 1:

According to system-wide section is fixed the diverse location residing for Traffic flow detecting device, system-wide section is divided into 3 sons Section, wherein one section near section entrance is referred to as section, upstream, and a section exported near section is referred to as Downstream road section, remaining one section is referred to as section, middle reaches.

Step 2:

For the section, upstream described in step 1, section, middle reaches, downstream road section, by fixed pattern in each section Flow that Traffic flow detecting device observes, speed historical data, use Least Square Method to obtain traffic flow Model parameter a, b, c and d, it may be assumed that

U=a-(b × q-c)^d (1)

In formula, by the flow in certain section in the q representation unit time.

Step 3:

Section segmentation according to step 1 and the calculated model parameter of step 2, use diverse location traffic The average passage rate of the flow rate calculation correspondence position of current sensor actual measurement, its formula is:

u_l=a-(b × q_l-c)^d (2)

In formula, l represents that speed and flow are all the results observed when distance crossing l.

Step 4:

Passage rate meter according to diverse location in system-wide section calculated in step 3 (or different segmentation) Calculate the average passage rate of system-wide section, it may be assumed that

$u=\left({\∫}_0^L{u}_l\mathrm{dl}\right)/L---\left(3\right)$

In formula, L represents road section length.Formula (2) is substituted into formula (3), obtains:

$u=\left({\∫}_0^L\right[a-{(b\×q_l-c)}^d\left]\mathrm{dl}\right)/L---\left(4\right)$

In formula, u is i.e. for the calculated full road-section average of traffic flow observed according to diverse location in section Speed.

In actual applications, owing to the speed flowrate situation of change of each position on section, formula can not be obtained (4) can be reduced to:

$u={\mathrm{\Σ}}_{l=1}^{l=L}{\∂}_l(a-{(b\×q_l-c)}^d)/L---\left(5\right)$

In formula,For each segmentation Traffic flow detecting device weight to calculating Road average-speed.Can use true Real data automatic Fitting method of estimation obtains.

Step 5:

Set up the transfer equation of flow-speed-state, the road average speed in formula (5) is mapped to state The result in territory, mapping function is DSS, it may be assumed that

$S={\mathrm{\Σ}}_{l=1}^{l=L}{\∂}_l\mathrm{DSS}(a-{(b\×q_l-c)}^d)/L---\left(6\right)$

In formula, S represents the traffic behavior of road,Represent that each Traffic flow detecting device is to calculating road traffic state Weight.

Urban road traffic state method of estimation based on section segmentation the most according to claim 1, also Including:

When section newly increases during (or minimizing) n Traffic flow detecting device, need to formula (6) increase (or Reduce) the speed-flow transformation result of Traffic flow detecting device overlay segments, it may be assumed that

$u={\mathrm{\Σ}}_{l=1}^{l=L\±n}{\∂}_l\mathrm{DSS}(a-{(b\×q_l-c)}^d)/(L\±n)---\left(7\right)$