CN109886467B

CN109886467B - Urban ULS and road integrated cargo transportation network flow distribution system and method

Info

Publication number: CN109886467B
Application number: CN201910053859.1A
Authority: CN
Inventors: 陈一村; 董建军; 陈志龙; 许元鲜; 尚鹏程; 任睿
Original assignee: Army Engineering University of PLA
Current assignee: Army Engineering University of PLA
Priority date: 2019-01-21
Filing date: 2019-01-21
Publication date: 2023-06-30
Anticipated expiration: 2039-01-21
Also published as: CN109886467A

Abstract

The invention discloses a distribution system and a distribution method of an integrated freight network of an urban ULS and a road, which aim to avoid singleness and limitation of urban road transportation and ULS function configuration and realize resource integration of the integrated freight network system so as to improve urban logistics transportation. The method comprises the following steps: based on ULS network and urban road network, virtual nodes and line segments are added to form a state augmentation network of integrated transportation; then, a random utility theory is adopted to respectively establish generalized cost models generated in the process of transporting goods from a logistics park to a transit site, a distribution center, a terminal network point, a client and other destinations; according to the initial and final points of cargo transportation, solving a feasible transportation path by using a shortest path algorithm according to equal parts within the allowable error range, and updating a feasible path set; finally, according to the user balance theory, a Logit loading model is adopted to load and update the cargo flow on a state augmentation network (SAM network) respectively, so as to obtain the cargo flow of the road transportation and ULS on the ground.

Description

Urban ULS and road integrated cargo transportation network flow distribution system and method

Technical Field

The invention relates to a freight traffic distribution method for urban overground and underground, in particular to a freight balanced distribution method for urban ULS and road integrated transportation.

Background

With the improvement of the demand of e-commerce on the accessibility and flexibility of goods transportation, the urban road traffic jam and the living environment deterioration caused by the continuous increase of the number of goods transportation vehicles are becoming the problems to be solved urgently in the urban traffic field. Urban underground logistics system (Underground Logistics System, ULS) is a brand new concept logistics system for transporting and sorting and distributing solid cargoes through underground pipelines, tunnels and other transportation channels by using automatic transportation as a bearing tool. ULS has solved "logistics bottleneck" problem of urban logistics distribution well by virtue of its advantages of not occupying ground roads, high efficiency, punctual, like: ULS is not limited by traffic control and is affected by traffic jam, so that all-weather delivery time is realized; the goods circulate underground, so that intelligent and uninterrupted logistics transportation can be realized, the transportation process is effectively linked, and the timeliness of the goods transportation is ensured; the underground logistics distribution system is directly connected to terminals such as communities, enterprises, hospitals and the like, so that the problem that express delivery personnel stop and put in disorder can be solved; the distribution vehicles on the urban ground roads are eliminated, the urban traffic jam problem is relieved, the emission of automobile exhaust is reduced, and the environment is protected. ULS, a viable and innovative green logistics way, has become an important direction for model innovation in the logistics industry.

The urban ULS transfers the goods to the underground, and can realize the integrated goods transportation of the urban overground and underground. In order to avoid unilateral performance and limitation of ULS (ULS) transportation configuration, the problem of transportation and distribution of the ULS and road integrated transportation network is studied in the urban range, so that the resource integration of the ULS and a ground road transportation system can be effectively enhanced, the problem of integration and optimization of resource configuration of urban logistics in a co-distribution mode, transportation lines, service functions and the like is favorably analyzed, the bottleneck lines and sites influencing logistics transportation are fundamentally analyzed, and decision support is provided for improvement of urban logistics distribution in planning.

Disclosure of Invention

The invention aims to: the invention aims to solve the technical problem of providing a distribution system and a distribution method of an urban ULS and road integrated cargo transportation network, which can realize reasonable distribution of urban cargo overground and underground flow and achieve network balance.

The urban ULS and road integrated cargo transportation network flow distribution system provided by the invention can adopt the following technical scheme:

an urban ULS and road integrated cargo network distribution system, comprising:

the initialization module is used for determining a line set transported by the vehicle and the underground logistics system, adding virtual nodes and edges to convert a transport network into a SAM network, selecting a path update threshold value, selecting line changing times, selecting a broad-sense expense acceptance degree, selecting loading times and confirming the loading amount of cargoes each time;

the path set generating module is used for solving feasible transportation paths by using a shortest path algorithm according to the initial and final points of cargo transportation according to equal parts and updating the feasible path set;

the path flow loading module is used for executing path flow distribution;

the judging and updating module is used for updating the path flow according to whether the constraint condition is met or not, and updating the loaded cargo quantity, the network operation energy and the path flow at the same time;

and the convergence judging module is used for carrying out convergence judgment on the increment of the path flow.

The invention provides a distribution method of an urban ULS and road integrated cargo network, which comprises the following steps:

an urban ULS and road integrated cargo transportation network flow distribution method comprises the following steps:

step A, forming a state augmentation network of integrated transportation by adding virtual nodes and line segments according to a ULS network and an urban road traffic network;

step B, adopting a random utility theory to respectively establish generalized cost models generated in the process of transporting goods from a logistics park to a transit station, a distribution center, a terminal network point, a client and other destinations; the origin and destination points are connected through a road traffic network, ULS trunk lines and branch lines; the generalized cost calculation of cargo transportation is divided into road transportation, ULS trunk transportation, ULS branch transportation and line replacement, and the specific process is as follows:

the generalized cost of transporting goods on the road comprises the transportation time of the goods in the vehicle, waiting time of a logistics site, fixed transportation cost and safety accident loss cost; wherein, the transportation time in the vehicle is calculated by adopting a BPR function set by the United states department of public road; calculating the waiting time of the logistics site according to the departure frequency of the truck; the fixed cost of transportation is determined according to mileage of cargo transportation; the cost of the safety accident loss of urban road transportation is influenced by factors such as road condition, road flow, weather condition and the like, and the linear relation between the road flow and the cost of the safety accident loss is utilized for calculation;

step B2, the generalized cost of track type transportation of the underground logistics system comprises the in-vehicle transportation time of cargoes, the waiting time of a logistics station and the fixed cost of transportation; wherein, the transportation time in the vehicle is the ratio of the distance to the speed; the waiting time of the logistics site can be expressed as half of the time interval of the vehicle head;

step B3, the automatic trolley type transportation waiting time of the underground logistics system is 0; thus, the broad cost of automated cart-based transportation of underground utility systems includes the in-car transportation time and fixed cost of transportation of cargo; wherein, the transportation time in the vehicle is the ratio of the distance to the speed;

c, solving a feasible transportation path by using a shortest path algorithm in equal parts within the allowable range of error according to the start and stop points of cargo transportation based on the state augmentation network obtained in the step A, and updating a feasible path set; the specific process is as follows:

step C1, updating the threshold value eta by setting a path ₁ Controlling the number of times of solving the path set during flow loading, and generating a feasible path set by using a K shortest algorithm; wherein the number of effective paths in the path set is determined by the number eta of line changing times ₂ And generalized cost acceptance degree eta ₃ To determine;

and D, finally, according to a user balance theory, loading and updating the cargo flow on the SAM network respectively by adopting a Logit loading model to obtain the cargo flow of the ground road transportation and ULS.

Step D1, the increment of the path flow rate of the above-ground and underground integrated cargo transportation problem is expressed as:

wherein q ^w Representing loading of cargo between OD and WAn amount of; θ ₁ Representing uncertainty in customer broad cost understanding of the shipping path;

representing the generalized cost of any OD versus w cargo on path p, is calculated by the following equation:

step D2, the above-ground road traffic and the underground logistics system have respective capacity limitations, and constraint conditions are as follows:

wherein when the line l includes the road segment a on the path p, delta _l (p, a) is 1, otherwise 0;

and

the value of the path p is 1 when the path p takes the station s as a departure point and an arrival point of branch transportation of the underground logistics system, and is 0 otherwise; k (K) _l Representing the transport capacity of the line i cargo; />

And->

When the branch line transportation is respectively indicated, the station s has the maximum berth limit of the AGV trolley and the AGV processing capacity;

road segment performance limits representing road transportation and underground logistics system transportation;

and->

Representing the capacity limitations of the underground commodity stream transport spur site, respectively.

Furthermore, the urban integrated cargo transportation network is formed by further using an above-ground road transportation line, an underground logistics trunk line and a branch line, so that the time and the cost consumed in the cargo transportation process between the starting and the ending points generate pollution factors, and the pollution factors are converted into the generalized cost of economics for calculation and analysis.

Further, the above-ground road transport network of cargoes is transported on urban ground roads by means of trucks and van trucks; the ULS trunk is transported by adopting a large-diameter Cargo Cap technology; the ULS branch line adopts an AGV; there will be one or more transport paths between any of the destination points, each transport path may include one or more routes and one or more transport modes.

The beneficial effects are that: compared with the existing urban road traffic network, the freight network flow distribution system and method provided by the invention consider the integrated freight method of ULS and urban road traffic network. To form a continuously developed urban logistics distribution system, the advantages of different transportation systems must be exerted. In order to avoid the unilateral and limited performance of the underground logistics system, the method is favorable for the resource integration of the underground logistics system and the ground road transportation system, the resource integration of the urban logistics distribution mode and the line node functional configuration, and the decision support is provided for the improvement of urban logistics distribution. The invention breaks through the existing freight distribution method of a single network, provides a distribution method of over-ground and under-ground freight transportation, and solves the problem of flow balance distribution of ULS and urban road traffic integrated freight transportation networks. The method can be used for optimizing urban logistics transportation, solving the problem of urban traffic jam, and ensuring that ULS and other transportation facilities can be matched with each other and operated cooperatively.

Drawings

FIG. 1 is a flow chart of a random utility based ULS and road integrated cargo network distribution method.

Fig. 2 is a schematic diagram of an urban ULS and road integrated shipping network.

Fig. 3 is a schematic diagram of an integrated shipping network transportation route and path.

Detailed Description

The integrated transport network of the urban underground logistics system and the above-ground roads comprises a series of logistics sites and transport sections, as shown in fig. 1. The trunk line m2 and the branch line m3 of the underground commodity circulation system together carry underground transportation of the cargo. The ground road transport network of goods mainly relies on traditional freight tools such as trucks, van trucks and the like to transport on urban ground roads. For the purpose of network explanation, we adopt large diameter Cargo Cap technique transportation, it has independent road right and fixed operation time's rail transportation mode, can transport the container, and the cargo transportation ability is big. The branch line adopts AGVs, and is a trolley with an automatic navigation device, so that the on-the-fly service can be realized, and the cargo transportation capacity is relatively small. These techniques are optional and allow for automated transportation of cargo under the ground. Compared with the ground transportation road affected by complicated environments such as city planning, passenger transport, weather and the like, underground transportation is free from interference, and the transportation distance between stations can be shortened by approximate straight line connection of tunnels. Even though some logistics sites cannot be directly connected through above-ground roads, but underground is not limited, such as logistics sites s ₂ To s ₄ Connected only by a branch line. Each logistics site is connected with underground and overground spaces simultaneously, has the functions of loading, unloading and transferring cargos, and can realize the change of the cargo in the transportation mode.

There will be multiple transport paths between an OD demand pair, each transport path may include multiple lines and multiple modes of transport. In order to better explain the integrated transportation process of goods on the ground and underground, a logistics site s is adopted ₃ To s ₂ For example, freight transportation. Drawing of the figure3 (a) and (b) respectively refer to an overground and underground integrated transportation line and road section. Each road section comprises a plurality of transportation modes and respectively belongs to different lines. The service frequency, speed of transportation and logistics capacity of trucks on each transportation route are different, vary with the amount of goods, and each transportation route may be selected due to customer variability, incompleteness of information conditions and the appeal of new technology. We assume that all customers choose the travel path with minimal generalized cost of shipment, rather than unilateral consideration of shipping cost or shipping time. Taking one of the paths as an example, cargo passes from the mass flow site s through the mass flow branch l5 ₃ Arrive s ₁ Thereafter, the goods are time and cost consuming to unload, transfer, and load onto the underground trunk l4 and ultimately transported to the logistics site s ₂ The time and cost spent in these transportation processes, we have transformed into a broad cost of economics for computational analysis.

The underground and overground integrated cargo transportation problem is illustrated by a transportation network g= (S, L, M), where S represents a logistics site set and L and M represent a transportation line set and a transportation mode set, respectively. The set of transport network segments is denoted as A, the transport network has a plurality of points of origin and destination for the transport of goods, the set is denoted as W, and the demand for goods at any point of origin and destination W is denoted as q ^w 。

Step 1 initialization

A line set L is determined for truck and underground logistics system transportation.

Adding virtual nodes and edges converts the transport network into a SAM network. Wherein the SAM network is a State-authenticated Multi-mode network (SAM) for integrated transport.

Selecting a path update threshold η ₁ Number of line changes η ₂ Generalized cost acceptance degree eta ₃ Number of loads η ₄ The cargo loading amount per time is:

iteration number n=0, and each line flow x is set _l For 0, the loaded cargo quantity q=0, and the total capacity x=0.

Step 2 Path Generation

The path set P1 is generated using a K-shortest path algorithm.

If the path is

And n is _p ≤η ₂ ，/>

P epsilon P ^w Adding Path p to the active Path set of OD requirement vs. w>

Step 3 execution Path traffic distribution

Iteration number: n=n+1.

Calculating generalized costs for paths in an active path set

Based on the calculation, the cargo quantity Deltaq of each Origin-destination (OD) ^w Is loaded according to the goods distribution scheme

And on each path of each OD pair, after each OD demand pair is loaded, the flow update in step 4 is needed.

Step 4 State update

Calculating constraint condition w, if yes, updating path flow, otherwise, updating path flow

Deleting in the active path set and deleting the edges which do not meet the constraint in the network.

Updating the loaded cargo quantity Q ₁ ＝△q ^w +Q ₁ Network operation capability

Path traffic

Step 5 Convergence

If it is

The procedure is terminated. Otherwise, if->

Turning back to step 2, Q ₁ Otherwise, go back to step 3.

Step a, a transportation network g= (S, L, M) to illustrate the underground and overground integrated cargo transportation problem, where S represents a logistics site set, and L and M represent a transportation line set and a transportation mode set, respectively. The collection of transport network segments is denoted as A, the transport network has a plurality of points of origin and destination of the cargo transport, the collection is denoted as W, and the cargo demand at any point of origin and destination W is denoted as q ^w . According to the ULS network and the urban road traffic network, a status augmentation network (SAM network) of integrated transportation is formed by adding virtual nodes and line segments;

step B, adopting a random utility theory to respectively establish generalized cost models generated in the process of transporting goods from a logistics park to a transit station, a distribution center, a terminal network point, a client and other destinations; the origin and destination points are connected through road traffic network, ULS trunk line and branch line; the generalized cost calculation of cargo transportation is mainly divided into four parts of road transportation, ULS trunk transportation, ULS branch transportation and line replacement, and the specific process is as follows:

the generalized cost calculation formula for road transportation goods is as follows:

wherein m1 represents road transportation in a transportation mode;

the in-vehicle transportation time is expressed as:

wherein v is _sl Is the flow of cargo on the road segment,

is the capacity limit of line L, L _p Representing the distance of path p; />

Representing the speed of transport on path p; alpha ^m1 And beta ^m1 Is a road transportation time parameter, and the values are generally 0.15 and 4 respectively.

Waiting time of goods in logistics site

Can be expressed as:

wherein alpha is _f Is a positive parameter, f _l ^m1 Represents the planned departure frequency of the freight vehicle on line i,

and->

Is a positive calibration parameter, θ is a headway coefficient.

The safety accident loss cost of urban road transportation is influenced by factors such as road conditions, road flow, weather conditions and the like, the road flow and the safety accident loss cost are in linear relation, and the higher the road flow is, the higher the safety accident loss cost is. Expressed as:

wherein, the liquid crystal display device comprises a liquid crystal display device,

is the average lost cost of the safety accident.

Step B2, the underground logistics system is fully automatic and unmanned in the whole transportation process, so that the safety accident loss cost is ignored in calculation; the generalized cost of the rail type transportation of the underground logistics system comprises the in-car transportation time of goods, the waiting time of a logistics site and the fixed cost of transportation; wherein, the transportation time in the vehicle is the ratio of distance to speed; the waiting time of the logistics site can be expressed as half of the time interval of the vehicle head;

the broad cost of mass transit of a subsurface logistics system can be expressed as:

wherein m2 represents a transportation mode of a main line transportation of the underground logistics system; the underground logistics system trunk line has independent tracks, and the transportation time in the underground logistics system trunk line is longer than that in the underground logistics system trunk line

Is the ratio of distance to speed, and can be expressed as:

indicating the speed of transport on path p.

Logistics site latency

Can be expressed as:

wherein f _l ^m2 And

representing planned departure frequency and capacity limits of a cargo cap on line l; />

And->

Is a positive check parameter; />

Representing the amount of cargo that a logistics system trunk line/is loaded before s-site and unloaded after s-site;

step B3, automatic trolley type transportation of the underground logistics system can realize the arrival and service of goods, and the waiting time is 0; thus, its broad cost includes the in-car transit time of the cargo and the fixed cost of the transit; wherein, the transportation time in the vehicle is the ratio of the distance to the speed;

the broad cost of branch transportation of a subsurface logistics system can be expressed as:

wherein m2 represents the transportation mode of branch transportation of the underground logistics system and the transportation time in the vehicle

Expressed as:

indicating the average speed of transport of the AGV trolley.

Step B4, when the goods change the transportation line at the logistics site, the goods are required to be unloaded, transferred and loaded, and the time value and the fixed cost of the three processes form the generalized expense of the goods line change;

the generalized cost of line change of goods is expressed as:

representing the time cost of line changing; />

And->

Lambda represents the amount of goods unloaded and loaded at the logistics site, respectively _s Representing the capacity of a logistics site to load and unload goods in unit time; c ^tf Representing the fixed cost of the cargo lane change.

C, solving a feasible transportation path by using a shortest algorithm in equal parts within an error allowable range according to the origin-destination of cargo transportation based on the state augmentation network obtained in the step A, and updating a feasible path set; the specific process is as follows:

step C1, we update the threshold η by setting a path ₁ To control the number of times the path set is solved when traffic is loaded, and a K-shortest algorithm is used to generate a feasible path set. Wherein the number of effective paths in the path set passes through the line changing times eta ₂ And generalized cost acceptance degree eta ₃ To determine;

The increase in path flow for the step D1, above-ground and below-ground integrated cargo transportation problem can be expressed as:

wherein q ^w Representing the load of the OD to the cargo between w; θ ₁ Representing uncertainty in customer broad cost understanding of the shipping path;

representing the generalized cost of any OD versus w cargo on path p can be calculated by the following formula:

and

respectively, when the path p uses the station s as the underground flow systemWhen the starting point and the arrival point of the branch line transportation are unified, the value is 1, otherwise, the value is 0; k (K) _l Representing the transport capacity of the line i cargo; />

And->

When the branch line transportation is respectively indicated, the station s has the maximum berth limit of the AGV trolley and the AGV processing capacity; />

Road segment performance limits representing road transportation and underground logistics system transportation; />

And

representing the capacity limitations of the underground commodity circulation transportation spur site, respectively.

In addition, the invention may be embodied in many specific forms and should not be construed as limited to the embodiments set forth herein. It should be noted that modifications and adaptations to the present invention may occur to one skilled in the art without departing from its principles and are intended to be within the scope of the present invention. The components not explicitly described in this embodiment can be implemented by using the prior art.

Claims

1. The urban ULS and road integrated cargo transportation network flow distribution method is characterized by comprising the following steps of:

step B, adopting a random utility theory to respectively establish a generalized cost model generated in the process of transporting goods from a logistics park to a transit station, a distribution center and a terminal website and a customer destination; the points are connected through a road traffic network, ULS trunk lines and branch lines; the generalized cost calculation of cargo transportation is divided into road transportation, ULS trunk transportation, ULS branch transportation and line replacement, and the specific process is as follows:

step B1, generalized cost of road transportation of goods comprises the transportation time of the goods in a vehicle, the waiting time of a logistics site, the fixed cost of transportation and the loss cost of safety accidents; wherein, the transportation time in the vehicle is calculated by adopting a BPR function set by the United states federal road agency; calculating the waiting time of the logistics site according to the departure frequency of the truck; the fixed cost of transportation is determined according to mileage of cargo transportation; the cost of the safety accident loss of urban road transportation is influenced by road conditions, road flow and weather condition factors, and the linear relation between the road flow and the cost of the safety accident loss is utilized for calculation;

step B2, the generalized cost of track type transportation of the underground logistics system comprises the in-car transportation time of cargoes, the waiting time of a logistics site and the fixed cost of transportation; wherein, the transportation time in the vehicle is the ratio of the distance to the speed; the waiting time of the logistics site can be expressed as half of the time interval of the vehicle head;

step B3, the automatic trolley type transportation waiting time of the underground logistics system is 0; thus, the broad expense of automated cart-based transportation of underground commodity circulation systems includes the in-car transportation time and fixed cost of transportation of the cargo; wherein, the transportation time in the vehicle is the ratio of the distance to the speed;

step C1, updating the threshold value eta by setting a path ₁ Controlling the number of times of solving the path set during flow loading, and generating a feasible path set by using a K shortest algorithm; wherein the number of effective paths in the path set passes through the line changing times eta ₂ And generalized cost acceptance degree eta ₃ To determine;

step D, finally, according to a user equilibrium theory, loading and updating the cargo flow on the SAM network respectively by adopting a Logit loading model to obtain the cargo flow of the ground road transportation and ULS;

wherein Δq ^w Indicating the load of the cargo between the origin and destination OD and w; θ ₁ Representing uncertainty in customer broad cost understanding of the shipping path;

step D2, the above-ground road traffic and the underground logistics system have respective capacity limitations, and the constraint conditions are as follows:

and->

And->

Respectively representing the maximum berth limit and the AGV processing capacity of an AGV trolley at a station s during branch line transportation;

and->

2. The urban ULS and road integrated cargo network distribution method of claim 1, wherein: the urban integrated cargo transportation network consists of an overground highway transportation line, an underground logistics trunk line and branch lines; the transport network comprises a series of logistics sites and transport segments.

3. The urban ULS and road integrated cargo network distribution method of claim 1, wherein: the time and cost consumed in the transportation process between the origins and the destinations of the goods generate pollution factors, and the pollution factors are converted into the generalized cost of economics for calculation and analysis.

4. The urban ULS and road integrated cargo network distribution method according to claim 2, wherein the above-ground road transport network of cargo is transported on urban ground roads by means of trucks and vans; the ULS trunk is transported by adopting a large-diameter Cargo Cap technology; the ULS branch line adopts an AGV; there will be one or more transport paths between any of the destination points, each transport path may include one or more routes and one or more transport modes.

5. An urban ULS and road integrated cargo network distribution system based on the urban ULS and road integrated cargo network distribution method according to any one of claims 1 to 4, characterized by comprising:

the initialization module is used for determining a line set transported by a vehicle and an underground logistics system, adding virtual nodes and edges, converting a transport network into a SAM network, selecting a path update threshold value, selecting line changing times, selecting generalized expense acceptance degree, selecting loading times and confirming cargo loading amount each time;

the path set generating module is used for solving the feasible transportation paths by using a shortest path algorithm according to the initial and final points of cargo transportation according to equal parts and updating the feasible path set;

the path flow loading module is used for executing path flow distribution;