CN111260947B - Road network reachable range analysis method based on flooding algorithm - Google Patents

Road network reachable range analysis method based on flooding algorithm Download PDF

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CN111260947B
CN111260947B CN202010103865.6A CN202010103865A CN111260947B CN 111260947 B CN111260947 B CN 111260947B CN 202010103865 A CN202010103865 A CN 202010103865A CN 111260947 B CN111260947 B CN 111260947B
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road network
way
road
packet
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CN111260947A (en
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朱熙
安宇航
朱少川
曹先彬
杜文博
张明远
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Beihang University
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    • G—PHYSICS
    • G08—SIGNALLING
    • G08G—TRAFFIC CONTROL SYSTEMS
    • G08G1/00—Traffic control systems for road vehicles
    • G08G1/09—Arrangements for giving variable traffic instructions
    • G08G1/0962—Arrangements for giving variable traffic instructions having an indicator mounted inside the vehicle, e.g. giving voice messages
    • G08G1/0967—Systems involving transmission of highway information, e.g. weather, speed limits
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06Q—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
    • G06Q10/00—Administration; Management
    • G06Q10/06—Resources, workflows, human or project management; Enterprise or organisation planning; Enterprise or organisation modelling
    • G06Q10/063—Operations research, analysis or management
    • G06Q10/0631—Resource planning, allocation, distributing or scheduling for enterprises or organisations
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06Q—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
    • G06Q50/00—Systems or methods specially adapted for specific business sectors, e.g. utilities or tourism
    • G06Q50/10—Services
    • G06Q50/26—Government or public services
    • G06Q50/40—
    • 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
    • G08G1/0104—Measuring and analyzing of parameters relative to traffic conditions
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A10/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE at coastal zones; at river basins
    • Y02A10/40—Controlling or monitoring, e.g. of flood or hurricane; Forecasting, e.g. risk assessment or mapping

Abstract

The invention discloses a road network reachable range analysis method based on a flooding algorithm, and belongs to the technical field of traffic area reachability. For a selected vehicle A, determining a traffic area range by using maximum speed and time, adding road numbers in the range into a road network Set _ way, screening, adding start and end point numbers corresponding to each screened road into a road node Set _ node, and constructing a road network node class by using all node numbers: meanwhile, constructing a road network connection edge class according to the road numbers in the screened road network Set _ way; connecting the N road network node classes and the M road network connecting edge classes to construct a road network model; and finally, simulating the running of the selected vehicle A in the road network model by adopting a recursive flooding algorithm to obtain a reachable road network list, and distributing tasks for the vehicle A to realize accurate transportation operation. Compared with the existing method, the method is more accurate and the complexity of the calculation process is low.

Description

Road network reachable range analysis method based on flooding algorithm
Technical Field
The invention belongs to the technical field of traffic area reachability, and particularly relates to a road network reachability range analysis method based on a flooding algorithm.
Background
The vehicle reachable analysis refers to the step of comprehensively considering space factors and time factors for a specific vehicle and searching a traffic area where the vehicle can reach within a specified time.
Vehicle reachable analysis is a hot problem in researches such as logistics distribution and urban intelligent traffic. For a logistics company, the coverage range of the logistics service business is an important standard for measuring the service capacity of the logistics company, whether a distribution center can be reasonably selected or not is the key for realizing the full coverage of the logistics service, and accurate reachability analysis is an indispensable part for carrying out optimal decision on related problems; for urban traffic, the method can provide guidance for reasonable distribution of urban traffic resources by accurately analyzing the accessibility of taxis, network appointments and other vehicles in the city, so that the problems of urban traffic congestion, unreasonable resource distribution and the like are effectively solved.
The flooding algorithm is as follows: in a network, packets sent from any node through a router are sent to all other nodes connected to the router, which is a way to quickly disseminate route update information to each node throughout a large network. In the prior art, a flooding algorithm is mainly applied to the field of data communication systems, and is used for realizing transmission and exchange of data packets between host networks. However, the application of flooding algorithms in the traffic domain is rare.
At present, most of existing vehicle reachable area calculation methods are based on vehicle tracks, traffic areas are gridded according to distances between vehicle query points and boundary points, and then analysis is carried out based on shortest paths to obtain vehicle reachable areas. Another refinement introduces the impact of different time periods on the reachable region.
However, these methods are based on the space-time constraints of the regions between the vehicle query points and the boundary points, and do not perform accurate analysis according to the characteristics of different roads in the traffic region. For logistics distribution problems in remote areas, traffic road conditions are often very complex, and besides time constraints, problems such as road height limitation and heavy road limitation also influence transportation, so that accessibility analysis of the method is limited in application range and insufficient in accuracy.
Disclosure of Invention
Aiming at the problems, the invention provides a road network reachable range analysis method based on a flooding algorithm, which is used for constructing a road network according to the characteristics of different roads in a traffic area, and the flooding algorithm is used in the traffic road network to simulate the driving process of a vehicle so as to perform more accurate reachable analysis on the vehicle. Compared with the common vehicle reachable analysis, the method considers the complexity of the road in the traffic area, has wide application range and obviously improves the accuracy of the result obtained by analysis.
The road network reachable range analysis method based on the flooding algorithm comprises the following specific steps:
step one, setting given time as t, determining a traffic area range by using the maximum speed v of a vehicle A aiming at a certain selected vehicle A, and adding road numbers in the range into a road network Set _ way.
The traffic area range comprises: and (3) setting the given time as t and the selected maximum speed of the vehicle as v, wherein the determined traffic area range is a circle made by taking the position of the vehicle as the center of a circle and vt as the radius.
Step two, screening all roads in the road network Set _ way according to the information of the vehicle A;
and (3) screening roads in the area according to the height, the width and the load of the vehicle, sequentially judging whether the roads in the selected traffic area are matched with the vehicle information, removing the roads with inconsistent height, width, load and vehicle type limitations from the road network Set _ way, and using the remaining roads meeting the conditions for constructing a road network.
The Set _ way after screening is { wgid1, wgid2, … …, wgidM }; wgidM is the M-th road number that conforms to the height, width, and load information of the vehicle A.
Sequentially selecting each road from the screened road network Set _ way, and adding a starting point number and an end point number corresponding to each road into a road node Set _ node;
set _ node ═ { ngid1, ngid2, … …, ngidN }; ngidN is the Nth node number of the way from Set _ way.
Step four, constructing all node numbers in the road node Set _ node as road network node classes:
generating N road network Node classes Node _ way in the Set _ Node of the road Node Set, and forming a Set < Node _ way >, Set < Node _ way > - (Node _ way1, Node _ way2, … …, Node _ way, … …, Node _ way q, … …, Node _ way N };
each Node class Node _ way comprises a Node number ngid, a Set < Linked _ way > formed by a plurality of road network connecting edge classes and a flooding time value flood _ time.
The node number ngid corresponds to the number in the Set _ node; the element of the Set < Linked _ way > is all road network connecting edges connected with the node; the flooding time value flood _ time represents the remaining time value when flooding was performed from the node last time, and is 0 by default.
Step five, constructing a road network connection edge class according to the road numbers in the screened road network Set _ way;
generating M road network connection edge classes Link _ way if the road network Set _ way includes M objects, and forming a road network connection edge class Set < Link _ way > - (Link _ way1, Link _ way2, … …, Link _ way, …, Link _ way M };
each Link _ way includes a road number information wgid, a transit time information transit _ time, and a road network Node _ target.
The road number information wgid corresponds to the number in the Set _ way; the travel _ time value is the saved time for passing through each road; the Node _ target stores the road network Node _ way pointed by the road side Link _ way.
And step six, connecting the N road network node classes and the M road network connecting edge classes to construct a road network model.
The connection means that: assigning values to each connection edge class in the Set < Link _ way >, adding a point Node _ target, and simultaneously adding the point Node _ target to the Set < Link _ way > of the corresponding road network Node class;
the method specifically comprises the following steps: aiming at the Link _ waym of the side connection type, acquiring corresponding road information in a database according to a wgidm value of a corresponding road number; the road information comprises passing time, an end point number and a starting point number;
assigning the travel _ time of the Link _ way of the connecting edge type as the passing time of the corresponding road;
and finding the road network Node _ way corresponding to the end point number in the road network Node class Set < Node _ way > according to the end point number obtained by the road number wgidm, and using the road network Node _ way as the value of the Node _ target corresponding to the Link class Link _ way.
Meanwhile, according to the starting point number obtained by the road number wgidm, the road network Node _ way q corresponding to the starting point number is found in the Set < Node _ way >, and the connecting edge class Link _ way is added to the Set < Linked _ way > corresponding to the road network Node _ way q.
Step seven, simulating the running of the selected vehicle A in the road network model by adopting a recursive flooding algorithm to obtain a reachable road network list;
the method specifically comprises the following steps:
step 701, constructing the position and the state of the operation of the simulated vehicle A into a Packet type Packet _ car, initializing the Packet type Packet _ car, and defining a reachable road network Set _ concerned at the same time;
a Packet class Packet _ car containing a lifecycle and a Set _ router for the operation of the vehicle a;
the initial value of the life cycle is counter;
the Set _ router is used for recording the information of the road network connecting edge passed by the packet, and is composed of the number of the road network connecting edge passed by the packet, and the initial value is null;
the reachable road network Set _ associated is used for storing the road network connection edge number finally experienced by the vehicle a, and the initial value is null.
Step 702, finding a road network Node closest to the vehicle A in the road network Node class Set < Node _ way > as a source point, marking as Node _ way0, and receiving Packet class Packet _ car;
setting the life cycle value counter as t0。
Step 703 of judging t0If so, go to step 704; otherwise, the packet is finished, and step 708 is entered;
step 704, determine t0Whether the time is longer than the flooding time in the road network node, if so, entering step 705; otherwise, the packet is an invalid packet, and step 708 is entered;
step 705, judging whether a connecting edge which does not exist in the Set _ router exists in a connecting edge Set < Linked _ way > of the current road network node, if so, entering step 706; otherwise, the road network node is flooded, and step 708 is entered;
step 706, newly building a Packet _ new with time t0-twAdding the nonexistent continuous edge number into a Set _ router of a Packet _ new;
twcorresponding to the travel _ time of each network connection edge.
The process of adding the continuous edge number specifically comprises the following steps:
judging whether the number of the added continuous edge numbers is 1, if so, adding the corresponding continuous edge numbers into a Set _ router of a Packet _ new, otherwise, when the number of the continuous edge numbers is more than 1, adding the corresponding continuous edge numbers into a Set _ router of the Packet _ new according to each time t0-twSelecting the continuous edge corresponding to the time with the maximum difference value, and adding the continuous edge number into the Set _ router of the Packet _ new.
Step 707, taking the Node _ way1 pointed by the connecting edge number added to the Set _ router of the Packet _ new as the next road network Node for receiving the Packet _ new, and updating the flooding time travel _ time of the Node _ way1 to t0Returning to step 703, starting a new set of flooding calculations until a decision t is made0-twIs 0.
Step 708, storing the road network connection edge number in the Set _ router into the initially defined Set _ concerned, and removing the duplicate, and ending the algorithm;
the road network connection edge number in the Set _ router is the reachable road network list of the vehicle A.
And step eight, allocating tasks to the vehicle A according to the reachable road network list obtained in the road network model, and realizing accurate transportation operation.
The invention has the advantages and positive effects that:
1) the road network reachable range analysis method based on the flooding algorithm fully considers the complexity of roads in traffic areas around vehicles, carries out screening according to the characteristics of the roads, and independently considers the passing time of each route to construct a road network model.
2) The invention relates to a road network reachable range analysis method based on a flooding algorithm, which adopts the flooding algorithm, simulates the running of vehicles by using packets transmitted among nodes, and simultaneously carries out certain optimization aiming at the characteristics of a road network, and the calculation process has the characteristic of low time complexity.
Drawings
FIG. 1 is a flow chart of a road network reachable range analysis method based on a flooding algorithm according to the present invention;
FIG. 2 is a flow chart of a method for computing a reachable network list using a recursive flooding algorithm according to the present invention;
fig. 3 is an embodiment of the present invention for explaining the recursive flooding algorithm.
Detailed Description
The present invention will be described in further detail and with reference to the accompanying drawings so that those skilled in the art can understand and practice the invention.
The vehicle road network reachable range analysis method based on the flooding algorithm is suitable for performing reachability analysis on a specific vehicle within a given time, and finally calculating a traffic area where the vehicle is likely to arrive within a limited time; the specific process is as follows: firstly, determining the traffic area range according to input vehicle information and time information, then screening roads in the area according to vehicle characteristics, constructing a road network meeting requirements in the selected area into a specific road network model, simulating vehicle running in the road network by adopting a recursive flooding algorithm to obtain a reachable road network list, and finally allocating tasks to corresponding transport vehicles according to reachable results to realize accurate transport operation.
As shown in fig. 1, the specific steps are as follows:
step one, setting given time as t, determining a traffic area range by using the maximum speed v of a vehicle A aiming at a certain selected vehicle A, and adding road numbers in the range into a road network Set _ way.
The traffic zone range includes all the possible arrival zones of the vehicle A within the limited time, and the determination process is as follows:
firstly, inputting coordinates (lat, lon) of a vehicle A, a vehicle maximum speed v and a limited time t; then, taking the coordinates (lat, lon) of the vehicle A as the center of a circle, vt as the radius as a circle C, wherein the range of the circle C is the range of the traffic area; the roads within the circle C are numbered and added to the road network Set _ way.
The selected traffic zone needs to contain all the possible arrival zones of the vehicle within a defined time, so as to guarantee the accuracy of the subsequent analysis calculation. Meanwhile, the area needs to be as small as possible, so that invalid calculation is reduced in the subsequent analysis and calculation process. Therefore, a circle C is selected as the selected area, which is the minimum area under the premise of ensuring all possible areas to be included.
Step two, screening all roads in the road network Set _ way according to the information of the vehicle A;
the vehicle a information includes: and sequentially calling each road in the road network Set _ way from the database, comparing the height, width and load information of each road with the height, width and load of the vehicle information respectively according to the height, width and load information of each road, and removing the roads which do not meet the height, width and load information of the vehicle A from the road network Set _ way.
The Set _ way after screening is { wgid1, wgid2, … …, wgidM }; wgidM is the M-th road number that conforms to the height, width, and load information of the vehicle A.
The purpose of the screening in the step is to eliminate the road network that the vehicle can not pass through. In the distribution problem of partial remote areas, the conditions that the road conditions of a large number of roads are poor and the roads are not repaired for a long time exist, and the accessibility analysis after the partial roads are removed is very important for improving the accuracy of the obtained result.
Sequentially selecting each road from the screened road network Set _ way, and adding a starting point number and an end point number corresponding to each road into a road node Set _ node;
set _ node ═ { ngid1, ngid2, … …, ngidN }; ngidN is the Nth node number of the way from Set _ way.
Step four, constructing all node numbers in the road node Set _ node as road network node classes:
generating N road network Node classes Node _ way in the Set _ Node of the road Node Set, and forming a Set < Node _ way >, Set < Node _ way > - (Node _ way1, Node _ way2, … …, Node _ way, … …, Node _ way q, … …, Node _ way N };
each Node class Node _ way is formed by abstracting the intersection points of different roads in the region, and comprises a Node number ngid, a Set < Linked _ way > formed by a plurality of road network connecting edge classes and a flooding time value flood _ time.
The node number ngid corresponds to the number in the Set _ node; the Set < Linked _ way > represents the road connected with the node, and the elements in the Set are the serial numbers of all road network connecting edges connected with the node; the flooding time value flood _ time represents the remaining time value when flooding was performed from the node last time, and is 0 by default.
Step five, constructing a road network connection edge class according to the road numbers in the screened road network Set _ way;
generating M road network connection edge classes Link _ way if the road network Set _ way includes M objects, and forming a road network connection edge class Set < Link _ way > - (Link _ way1, Link _ way2, … …, Link _ way, …, Link _ way M };
each Link _ way is formed by abstracting a single road in the region, and comprises road number information wgid, required passing time information travel _ time and a road network Node type Node _ target.
The road number information wgid corresponds to the number in the Set _ way; the travel _ time value is the saved time for passing through each road; the Node _ target represents the road network Node pointed by the Link, and the road network Node _ way pointed by the road Link _ way is stored.
And step six, connecting the N road network Node types Node _ way with the M road network connecting edge types Link _ way to construct a road network model.
The connection means that: assigning values to each continuous edge class in the Set < Link _ way >, and adding a pointing Node _ target; meanwhile, adding the Set to a Set < Linked _ way > of the corresponding road network node class;
the method specifically comprises the following steps: aiming at the Link _ waym of the side connection type, acquiring corresponding road information in a database according to a wgidm value of a corresponding road number; the road information comprises passing time, an end point number and a starting point number;
assigning the travel _ time of the Link _ way of the connecting edge type as the passing time of the corresponding road;
and finding the road network Node _ way corresponding to the end point number in the road network Node class Set < Node _ way > according to the end point number obtained by the road number wgidm, and using the road network Node _ way as the value of the Node _ target corresponding to the Link class Link _ way.
Meanwhile, according to the starting point number obtained by the road number wgidm, the road network Node _ way q corresponding to the starting point number is found in the Set < Node _ way >, and the connecting edge class Link _ way is added to the Set < Linked _ way > corresponding to the road network Node _ way q.
Step seven, simulating the running of the selected vehicle A in the road network model by adopting a recursive flooding algorithm to obtain a reachable road network list;
when the flooding calculation is carried out, a Packet class Packet _ car is provided as a medium which is propagated in a network in a flooding algorithm, and the position and the state of a simulated vehicle in operation are provided. Firstly, according to vehicle information, a node closest to a vehicle is found out from nodes to serve as a source point, a packet with initial time as input time is established, the source point receives the packet, and recursive flooding calculation is started.
As shown in fig. 2, specifically:
step 701, constructing the position and the state of the operation of the simulated vehicle A into a Packet type Packet _ car, initializing the Packet type Packet _ car, and defining a reachable road network Set _ concerned at the same time;
a Packet class Packet _ car containing a lifecycle and a Set _ router for the operation of the vehicle a;
the initial value of the life cycle is the counter and is used for recording the time left in the running process of the vehicle.
The Set _ router is used for recording the information of the road network connecting edge passed by the packet, and is composed of the number of the road network connecting edge passed by the packet, and the initial value is null;
the reachable network Set _ associated is used for storing the reachable network connection edge number finally experienced by the vehicle a, and the initial value is null.
Step 702, finding a road network Node closest to the vehicle A in the road network Node class Set < Node _ way > as a source point, marking as Node _ way0, and receiving Packet class Packet _ car;
setting the life cycle value counter as t0。
Step 703 of judging t0If so, go to step 704; otherwise, the packet has ended the lifecycle, go to step 708;
step 704, determine t0Whether the time is longer than the flooding time in the road network node, if so, entering step 705; otherwise, the packet is an invalid packet, and step 708 is entered;
step 705, judging whether a connecting edge which does not exist in the Set _ router exists in a connecting edge Set < Linked _ way > of the current road network node, if so, entering step 706; otherwise, the road network node is flooded, and step 708 is entered;
step 706, newly building a Packet _ new with time t0-twAdding the nonexistent continuous edge number into the Set _ router and using the nonexistent continuous edge number as a path Set _ router of a Packet _ new;
twcorresponding to the travel _ time of each network connection edge.
The process of adding the continuous edge number specifically comprises the following steps:
judging whether the number of the added continuous edge numbers is 1, if so, adding the corresponding continuous edge numbers into the Set _ router, otherwise, when the number of the continuous edge numbers is more than 1, adding the corresponding continuous edge numbers into the Set _ router according to each time t0-twSelecting the continuous edge corresponding to the time with the maximum difference, and adding the serial number of the continuous edge into the Set _ router.
As shown in fig. 3, it is determined whether a packet received by a node has validity: and judging whether the remaining time of the packet is greater than the flooding time recorded by the node, if so, determining the packet to be a valid packet, and flooding, otherwise, determining the packet to be an invalid packet, and ending.
The node B receives the packet from the node A for the flooding calculation, and if the remaining time of the packet is less than that of the packet from the node O, the result of the flooding calculation is always included in the calculation result of the packet from the node O, so the flooding calculation performed by the node B receiving the packet from the node A is invalid. The invention judges whether the packet is an invalid packet or not by comparing the residual time in the packet with the node flooding time before the flooding calculation is started, thereby avoiding the calculation of the invalid packet.
Step 707, taking the Node _ way1 pointed by the connecting edge number added to the Set _ router of the Packet _ new as the next road network Node for receiving the Packet _ new, and updating the flooding time travel _ time of the Node _ way1 to t0Returning to the step 703, performing recursion, and starting a new set of flooding calculations until the decision t is reached0-twIs 0.
Step 708, storing the road network connection edge number in the Set _ router into the initially defined Set _ concerned, and removing the duplicate, and ending the algorithm;
the road network connection edge number in the Set _ route ═ { wgid1, wgid2, … …, wgidK } is the reachable road network list of the vehicle a.
When the flooding algorithm of the recursive transfer is completely finished, the life cycle of all the packets for simulating the vehicle operation is completely finished, and the number recorded in the Set _ concerned is the road number which can be reached by the specific vehicle within the limited time. And (4) removing the repetition of the road numbers, sequencing and outputting the road numbers, and finishing the vehicle reachability analysis.
And step eight, allocating tasks to the vehicle A according to the reachable road network list obtained in the road network model, and realizing accurate transportation operation.
And displaying the road numbering result which can be reached by the specific vehicle A by means of an imaging interface or borrowing other devices for analysis, allocating tasks for the corresponding transport vehicles, and realizing accurate transport operation.
According to the method, a special road network model is established according to the characteristics of the traffic roads, the complexity of different roads in the area is fully considered, and the network is screened and established according to the road characteristics, so that the reachability analysis result is accurate and the application range is wide; and necessary information is extracted from the database into the model, so that a carrier is provided for subsequent recursive flooding calculation.
The invention adopts the flooding algorithm to simulate the running of the vehicle, and in the prior art, the flooding algorithm is mainly applied to the field of data communication systems and is rarely applied to the traffic field. The flooding algorithm performs recursive transmission of media packets in the network, each packet may represent a running vehicle, and the relevant parameters of the packet represent the location and state information of the running vehicle. And analyzing the transmission of each packet in the network to obtain an accurate reachability analysis result.
Meanwhile, the flooding algorithm is optimized for the vehicle problem, and for the special condition of simulating vehicle operation, the packets received by part of nodes are invalid packets, so that the condition of certain invalid calculation exists by adopting the common flooding algorithm, and a large amount of time is consumed. The invention optimizes the algorithm, increases the judging step of the packet effectiveness, avoids the invalid calculation of the part and reduces the time complexity of the algorithm.
The method provided by the invention is used for constructing the road network by considering the complexity of the road in the peripheral area of the specific vehicle, and analyzing the vehicle accessibility by using a flooding algorithm to obtain and output the result. Compared with the existing method, the obtained reachable road network has strong accuracy, and the method and the device have wide application range. Particularly, for some areas with complex traffic conditions, the method and the device provided by the invention can accurately judge whether the road allows vehicles to pass, so that the roads which cannot pass are eliminated before time and space reachable analysis is carried out, and the accuracy of the result is greatly improved.

Claims (5)

1. A road network reachable range analysis method based on a flooding algorithm is characterized by comprising the following specific steps:
step one, setting given time as t, determining a traffic area range by using the maximum speed v of a vehicle A aiming at a certain selected vehicle A, and adding road numbers in the range into a road network Set _ way;
step two, screening all roads in the road network Set _ way according to the information of the vehicle A;
the Set _ way after screening is { wgid1, wgid2, … …, wgidM }; wgidM is the M-th road number according with the height, width and load information of the vehicle A;
sequentially selecting each road from the screened road network Set _ way, and adding a starting point number and an end point number corresponding to each road into a road node Set _ node;
set _ node ═ { ngid1, ngid2, … …, ngidN }; ngidN is the Nth node number selected from the road in Set _ way;
step four, constructing all node numbers in the road node Set _ node as road network node classes:
generating N road network Node classes Node _ way in the Set _ Node of the road Node Set, and forming a Set < Node _ way >, Set < Node _ way > - (Node _ way1, Node _ way2, … …, Node _ way, … …, Node _ way q, … …, Node _ way N };
each Node class Node _ way comprises a Node number ngid, a Set < Linked _ way > formed by a plurality of road network connecting edge classes and a flooding time value flood _ time;
the node number ngid corresponds to the number in the Set _ node; the element of the Set < Linked _ way > is all road network connecting edges connected with the node; the flooding time value flood _ time represents the remaining time value of the last flooding from the node, and the default value is 0;
step five, constructing a road network connection edge class according to the road numbers in the screened road network Set _ way;
generating M road network connection edge classes Link _ way if the road network Set _ way includes M objects, and forming a road network connection edge class Set < Link _ way > - (Link _ way1, Link _ way2, … …, Link _ way, …, Link _ way M };
each Link _ way comprises road number information wgid, required passing time information travel _ time and a road network Node _ target;
the road number information wgid corresponds to the number in the Set _ way; the travel _ time value is the saved time for passing through each road; the Node _ target stores a road network Node _ way pointed by the road side Link _ way;
step six, connecting the N road network node classes and the M road network connecting edge classes to construct a road network model;
the connection means that: assigning values to each connection edge class in the Set < Link _ way >, adding a point Node _ target, and simultaneously adding the point Node _ target to the Set < Link _ way > of the corresponding road network Node class;
step seven, simulating the running of the selected vehicle A in the road network model by adopting a recursive flooding algorithm to obtain a reachable road network list;
the method specifically comprises the following steps:
step 701, constructing the position and the state of the operation of the simulated vehicle A into a Packet type Packet _ car, initializing the Packet type Packet _ car, and defining a reachable road network Set _ concerned at the same time;
a Packet class Packet _ car containing a lifecycle and a Set _ router for the operation of the vehicle a;
the initial value of the life cycle is counter;
the Set _ router is used for recording the information of the road network connecting edge passed by the packet, and is composed of the number of the road network connecting edge passed by the packet, and the initial value is null;
the reachable road network Set _ concerned is used for storing the road network connection edge number finally experienced by the vehicle A, and the initial value is null;
step 702, finding a road network Node closest to the vehicle A in the road network Node class Set < Node _ way > as a source point, marking as Node _ way0, and receiving Packet class Packet _ car;
setting the life cycle value counter as t0；
Step 703 of judging t0If so, go to step 704; otherwise, the packet is finished, and step 708 is entered;
step 704, determine t0Whether the time is longer than the flooding time in the road network node, if so, entering step 705; otherwise, the packet is an invalid packet, and step 708 is entered;
step 705, judging whether a connecting edge which does not exist in the Set _ router exists in a connecting edge Set < Linked _ way > of the current road network node, if so, entering step 706; otherwise, the road network node is flooded, and step 708 is entered;
step 706, newly building a Packet _ new with time t0-twAdding the nonexistent continuous edge number into a Set _ router of a Packet _ new;
twcorresponding to the travel _ time of each network connecting edge;
step 707, taking the Node _ way1 pointed by the connecting edge number added to the Set _ router of the Packet _ new as the next road network Node for receiving the Packet _ new, and updating the flooding time travel _ time of the Node _ way1 to t0Returning to step 703, starting a new set of flooding calculations until a decision t is made0-twIs 0;
step 708, storing the road network connection edge number in the Set _ router into the initially defined Set _ concerned, and removing the duplicate, and ending the algorithm;
the road network connection edge number in the Set _ router is the reachable road network list of the vehicle A;
and step eight, allocating tasks to the vehicle A according to the reachable road network list obtained in the road network model, and realizing accurate transportation operation.
2. The method for analyzing the reachable range of road network based on flooding algorithm of claim 1, wherein in the first step, the traffic area range includes: and (3) setting the given time as t and the selected maximum speed of the vehicle as v, wherein the determined traffic area range is a circle made by taking the position of the vehicle as the center of a circle and vt as the radius.
3. The road network reachable range analysis method based on flooding algorithm claimed in claim 1, wherein said vehicle a information in step two comprises: and sequentially calling each road in the road network Set _ way from the database, comparing the height, width and load information of each road with the height, width and load of the vehicle information respectively according to the height, width and load information of each road, and removing the roads which do not meet the height, width and load information of the vehicle A from the road network Set _ way.
4. The road network reachable range analysis method based on the flooding algorithm according to claim 1, wherein the connection in the sixth step is specifically: aiming at the Link _ waym of the side connection type, acquiring corresponding road information in a database according to a wgidm value of a corresponding road number; the road information comprises passing time, an end point number and a starting point number;
assigning the travel _ time of the Link _ way of the connecting edge type as the passing time of the corresponding road;
according to the end point number obtained by the road number wgidm, finding the road network Node _ way corresponding to the end point number in the road network Node Set < Node _ way >, and using the road network Node _ way as the value of the Node _ target corresponding to the Link class Link _ way;
meanwhile, according to the starting point number obtained by the road number wgidm, the road network Node _ way q corresponding to the starting point number is found in the Set < Node _ way >, and the connecting edge class Link _ way is added to the Set < Linked _ way > corresponding to the road network Node _ way q.
5. The road network reachable range analysis method based on flooding algorithm of claim 1, wherein the process of adding the number of the connecting edge in step 706 is as follows:
judging whether the number of the added continuous edge numbers is 1, if so, adding the corresponding continuous edge numbers into a Set _ router of a Packet _ new, otherwise, when the number of the continuous edge numbers is more than 1, adding the corresponding continuous edge numbers into a Set _ router of the Packet _ new according to each time t0-twSelecting the continuous edge corresponding to the time with the maximum difference value, and adding the continuous edge number into the Set _ router of the Packet _ new.
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