CN112558559B - Series linear buffer and sequence recovery method thereof - Google Patents

Series linear buffer and sequence recovery method thereof Download PDF

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CN112558559B
CN112558559B CN202011254051.9A CN202011254051A CN112558559B CN 112558559 B CN112558559 B CN 112558559B CN 202011254051 A CN202011254051 A CN 202011254051A CN 112558559 B CN112558559 B CN 112558559B
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孙辉
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Southeast University
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    • G06N3/004—Artificial life, i.e. computing arrangements simulating life
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    • G05B19/02—Programme-control systems electric
    • G05B19/418—Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible manufacturing systems [FMS], integrated manufacturing systems [IMS], computer integrated manufacturing [CIM]
    • G05B19/41865—Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible manufacturing systems [FMS], integrated manufacturing systems [IMS], computer integrated manufacturing [CIM] characterised by job scheduling, process planning, material flow
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Abstract

A serial linear buffer zone and a sequence recovery method thereof belong to the field of mixed assembly line production planning and scheduling. The method specifically comprises the following steps: 1. inputting parameters of an upstream sequence, a target downstream sequence and a serial linear buffer area of a product; 2. setting and initializing parameters of a local search algorithm, and generating an initial product arrangement scheme and a downstream recovery sequence; 3. performing disturbance search on the current product arrangement scheme; 4. determining the release sequence of the disturbed product arrangement scheme by adopting an ant colony optimization algorithm to obtain an optimal downstream sequence; 5. determining an optimal recovery sequence and a corresponding product arrangement scheme; 6. if the termination condition of the local search algorithm is met, obtaining an optimal downstream recovery sequence and a corresponding product arrangement scheme; otherwise, turning to the step 3 to carry out the next local search. The invention has the advantage of being capable of restoring the disturbed upstream product sequence into the downstream sequence with the minimum or approximately minimum total product displacement compared with the target sequence.

Description

Series linear buffer and sequence recovery method thereof
Technical Field
The invention belongs to the field of production planning and scheduling of hybrid assembly lines, and particularly relates to a serial linear buffer zone and a sequence recovery method thereof.
Background
The hybrid assembly line is a low-cost and high-efficiency flexible production system, and different types of products can be continuously processed in a hybrid mode on the same assembly line. The mixed assembly line is widely applied to industries such as automobiles, electronics, household appliances, furniture and the like.
Taking a main engine plant of an automobile as an example, products on a hybrid assembly line sequentially pass through a vehicle body, painting and a final assembly workshop, and have different preferences and requirements on the production sequence of the products. Since most of the automobile assembly work is performed in the assembly plant, the automobile factory will usually determine the initial product sequence according to the production requirement planning of the assembly plant and issue the part requirement to the supplier in advance. On the other hand, in the production process, the automobile factory will always actively make proper adjustment to the product sequence from the upstream workshop according to the production requirements passing through different workshops, and various uncertainties in production (such as material shortage or order urgency) will also cause the position of the product in the planning sequence to change. In fact, most products have deviated in their actual position before the product sequence reaches the final assembly plant. Therefore, in order to allow assembly to be carried out as planned, reducing the negative impact on the manufacturer and supplier caused by temporary changes in the sequence, it is necessary to adjust the disturbed sequence before the final assembly plant, so as to restore it as far as possible to the planned product sequence.
Sequence adjustment (i.e., reordering) on a hybrid assembly line typically requires the use of different types of buffers. The linear buffer is a reordering facility which is most widely applied, and has the advantages of low cost, small occupied area, good reordering effect and the like compared with other reordering facilities such as an automatic storage system (ASRS). At present, linear buffers applied in enterprises are all independent single structures, and the reordering capability of the linear buffers is restricted by parameters of capacity (namely the total number of parking spaces in the buffers) and configuration (namely the number of lanes and parking spaces forming the buffers).
Although the reordering capability can be improved by increasing the capacity of the buffer, the required occupied area is also increased. Under the condition of limited workshop area, the sequence adjustment capability of the linear buffer zone is difficult to be obviously improved only by capacity expansion. The higher the sequence adjustment capability, the more flexible the production system. In fact, when the production demands of upstream and downstream plants are greatly different, a buffer is required to have stronger sequence adjustment capability, and the sequence adjustment capability is particularly required for recovering the disturbed initial planning sequence. Therefore, there is a need to improve the basic configuration and design concept of the conventional linear buffer, so as to significantly improve the sequence adjustment capability without adding large investment and occupation space. Through the research of documents, the current research is mainly focused on solving the problem of how to effectively utilize the conventional linear buffer for rearrangement, and there is no discussion about the configuration form or design scheme of the linear buffer.
Disclosure of Invention
Aiming at the problems in the prior art, the invention discloses a serial linear buffer and a sequence recovery method thereof, aiming at properly adjusting a disturbed upstream product sequence so as to obtain a downstream release sequence with the maximum similarity with a target sequence.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
a series linear buffer zone comprises a series linear buffer zone, wherein the series linear buffer zone comprises two sub-linear buffer zones and a middle transition parking space, the number L of lanes contained in each sub-linear buffer zone is the same, and the number W of parking spaces contained in each lane is also the same; according to the sequence of the upstream product flow, the two sub-linear buffer areas are respectively called an upstream buffer area and a downstream buffer area; the intermediate transition parking space is a product migration channel and a temporary storage place between the upstream buffer area and the downstream buffer area.
A method for sequence recovery of a series of linear buffers, comprising the steps of:
s1, acquiring the total number T of products in the upstream sequence, and acquiring the position p of the upstream product i in the downstream target sequenceiWherein T is less than or equal to 2 lxw, i is 1, 2.
S2, setting the maximum iteration number S of local searchmaxInitializing the iteration number s of local search to be 1; sequentially appointing a sub-buffer area and a lane to be entered for each product i according to the entering rule and the sequence of reaching the serial linear buffer area, and constructing an initial product arrangement scheme A (0) in the serial linear buffer area as an optimal arrangement scheme Aopt(ii) a Sequentially releasing all products from the serial linear buffer area according to a release rule to obtain a downstream sequence corresponding to A (0) as an optimal recovery sequence Sdown；
S3, disturbing the current product arrangement scheme A (S-1) according to the exchange rule to obtain an S generation product arrangement scheme A (S);
s4, obtaining a downstream sequence with the minimum total product displacement amount corresponding to the S generation product arrangement scheme A (S) by using an ant colony algorithm, and taking the downstream sequence as a global optimal downstream sequence Sopt(s)；
S5, if the global optimal downstream sequence Sopt(S) the total displacement of the product is less than the optimal recovery sequence SdownTotal displacement of the product in (1), will SdownIs updated to Sopt(s) optimizing the arrangement scheme AoptUpdated to A(s);
s6, judging whether the current iteration number meets the local search termination condition, namely S +1 > Smax(ii) a If not, let S be S +1, go to step S3 to perform the next search; if satisfied, the optimal recovery sequence SdownNamely the solved global optimal downstream sequence, the optimal arrangement scheme AoptIs a sum of SdownThe corresponding product arrangement scheme.
Preferably, in the step S2, the product is assigned to enter the sub-bufferThe rules of the zones are: in order to ensure that the product can smoothly enter the downstream buffer zone, an empty lane must be reserved in the upstream buffer zone before the downstream buffer zone is filled; when product i is at position p in the downstream target sequenceiWhen the number of the parking spaces is less than or equal to L multiplied by W, if the downstream buffer area has spare parking spaces, the product enters the downstream buffer area, otherwise, the product enters the upstream buffer area; when p isiWhen the speed is larger than L multiplied by W, if the upstream buffer area has empty parking spaces except one empty lane, the product enters the upstream buffer area, otherwise, the product enters the downstream buffer area.
Preferably, in step S2, the following rules are executed in the lane passing order for the product i designated to enter the sub-buffer:
(a.1) randomly selecting a lane if i is 1;
(A.2) if product i and the last product i in a certain unfilled lane in the designated sub-buffer zoneendPosition p in the downstream target sequenceiAnd
Figure GDA0003233198030000031
satisfy the requirement of
Figure GDA0003233198030000032
The product enters the lane;
(A.3) if the designated sub-buffer area has a vacant lane, randomly selecting a vacant lane;
(A.4) if the designated sub-buffer exists an unfilled lane, and
Figure GDA0003233198030000033
if the number of the unfilled lanes is 1, the product enters the lane; if the number of the unfilled lanes is more than 1, the product enters
Figure GDA0003233198030000034
The smallest of the lanes;
(A.5) if the designated sub-buffer exists an unfilled lane, and
Figure GDA0003233198030000035
if the number of unfilled lanes is 1, the product enters the laneA lane; if the number of the unfilled lanes is more than 1, the product enters
Figure GDA0003233198030000036
The smallest lane.
Preferably, the releasing rule in step S2 is used to continuously select product releases from the product candidate set until the serial linear buffer is empty, resulting in a downstream sequence; the method comprises the following specific steps:
(b.1) setting the release sequence number t of the product to 1;
(B.2) if a certain product i in the current product candidate set satisfies the condition: p is a radical ofiIf t, releasing the product i; otherwise, selecting the product with the minimum downstream target sequence position for release, and then updating the current product candidate set;
(b.3) moving to step (b.2) selecting the next release product until the tandem linear buffer is emptied by letting t be t + 1;
the product candidate set is composed of releasable products at the forefront of all non-empty lanes in the two sub-buffers.
Preferably, in step S3, the switching rule is used to select two products in the serial linear buffers, switch their respective positions, including the sub-buffers and the lanes, and adjust the parking order of the products in the sub-buffers and the lanes according to the first-in first-out principle, so as to obtain a new product arrangement scheme a (S);
when selecting a product to be exchanged, a product i is selected randomly first, and then another product m is selected according to the following method:
(C.1) if i is more than or equal to 1 and less than n, randomly selecting another product m on a different lane in the product set with the upstream sequence position of [1, n); wherein i is not equal to m, and n is the maximum position serial number of the end product of each lane of the upstream buffer in the upstream sequence;
(C.2) if n is less than or equal to i and less than or equal to T, randomly selecting another product m on a different lane in the product set positioned at the upstream sequence position of [ n, T ]; where i ≠ m.
Preferably, the ant colony algorithm in step S4 includes:
s41, determining the activity area of the artificial ant as x, y belonging to [1, T ]]A constrained rectangular region; the ant climbs to a node with x being T from an initial position, namely, one iteration is completed, and path nodes passing along the path are sequentially P (1, y)1)，P(2，y2)，...，P(t，yt)，...，P(T，yT) Wherein y istE {1, 2,. T } corresponds to the upstream sequence position number of the tth product released from the tandem linear buffer, T1, 2, …, T;
s42, setting and initializing algorithm parameters, including:
setting the number K of ants and the maximum iteration number r of the algorithmmaxLocal volatility ratio parameter rho of pheromonelPheromone global volatility ratio parameter ρgValue of [0, 1 ]]Parameter q between0A parameter alpha representing the importance degree of pheromone and parameters beta and gamma representing the importance degrees of other two heuristic information; wherein, 0 < pl＜1，0＜ρg＜1；
Initializing pheromone tau between any pair of adjacent products i and j in upstream sequenceijLet τ be at an initial timeij＝τ0In which τ is0Is a preset constant, i, j ═ 1, 2.., T; the iteration number r is initialized to 0; product candidate set Cand for each ant kkInitializing a set consisting of releasable products at the forefront end of each non-empty lane of an upstream buffer area and a downstream buffer area when the products are arranged according to an A(s) scheme, wherein K is 1, 2. The initial position of ant k is P (1, y)1)，y1Candidate set Cand for productkThe position serial number of the randomly selected product in the upstream sequence; releasing the selected products from the series linear buffer area, and updating a product candidate set Cand according to the head end product of the non-empty lanek(ii) a The current crawling step number is 1; initializing a globally optimal downstream sequence Sopt(s) the total displacement of the product is plus infinity;
s43, in the t-th step of the r-th iteration, each ant k climbs from the node where x is t to the node where x is t + 1; calculating heuristic information eta associated with each possible position where x is t +1j：
Figure GDA0003233198030000041
Wherein, the product j belongs to the product candidate set Candk；
dj＝t+1-pj，|djL represents the total displacement increment of the product in the downstream sequence caused by the release of the selected product j, vjWhether or not product j appears at its downstream target sequence position pjWhen t is equal to pjWhen, vjTaking 0, otherwise, taking 1; beta is represented by djThe parameter of importance, γ, is a number representing vjA parameter of degree of importance;
calculating ant k slave node Pk(t，yt) In the climbing direction Pk(t+1，yt+1) Transition probability p of a nodek(yt，yt+1)：
Figure GDA0003233198030000051
Wherein
Figure GDA0003233198030000052
Indicating product ytAnd yt+1Pheromone concentration in between; y ist+1∈Candk；
Ant k climbs to destination node P at t stepk(t+1，yt+1) Indicating that ant k selectively releases product y in upstream sequencet+1The selection is carried out according to the following method:
when q is less than q0When it is selected
Figure GDA0003233198030000053
The product with the largest value; otherwise according to the transition probability pk(yt，yt+1) Determining candidate products, wherein q is [0, 1 ]]Random numbers uniformly distributed among them;
updating product ytAnd yt+1Pheromone concentration between:
Figure GDA0003233198030000054
wherein
Figure GDA0003233198030000055
And
Figure GDA0003233198030000056
respectively representing the pheromone concentrations before and after updating;
when ant k crawls for one step, product candidate set Cand is releasedkAccording to the head end product of the non-empty lane, updating the product candidate set Candk；
Repeating the step S43 until T is T, completing an iteration, and recording the crawling path of each ant in the iteration;
s44, evaluating the downstream sequence of the iteration, including:
the ordinate of the path node passed by each ant crawling of the current iteration forms a downstream sequence, the total displacement of products of all K downstream sequences is calculated, and the downstream sequence with the minimum total displacement is selected as the optimal downstream sequence of the current iteration
Figure GDA0003233198030000057
If it is not
Figure GDA0003233198030000058
Is less than the global optimal downstream sequence Sopt(S) updating the total displacement of the productopt(s) is
Figure GDA0003233198030000059
S45, updating the global optimal downstream sequence SoptPheromone concentration between each pair of adjacent products in(s):
Figure GDA00032331980300000510
τijand τ'ijRespectively representing pheromone concentrations before and after update between products i and j, Z*For a globally optimal downstream sequence Sopt(s) a corresponding total displacement of the product;
let r be r +1, go to step S43 for the next iteration until the termination condition of the ant colony optimization algorithm is satisfied: r +1 ═ rmax。
Further preferably, the calculation formula of the total product displacement D in any downstream sequence Seq is:
Figure GDA00032331980300000511
Figure GDA00032331980300000512
wherein d isiIs the position serial number i of the product i in the SeqseqPosition number p in downstream target sequence with product iiA difference of (i) di＝iseq-pi。
Advantageous effects
1. Compared with the traditional linear buffer zone with the same capacity, the serial linear buffer zone disclosed by the invention has better sequence adjustment capability under the condition that the required floor area is almost unchanged;
2. the sequence recovery method disclosed by the invention uses a local search algorithm to search the arrangement mode of products in a series linear buffer area, then uses an ant colony optimization algorithm to obtain the release sequence of the products leaving the buffer area, and can recover an upstream sequence into a downstream sequence which has the smallest total product displacement or is approximately the smallest displacement compared with a target sequence.
Drawings
FIG. 1 is a schematic diagram of a design scheme for a serial linear buffer;
fig. 2 is a flowchart of a sequence recovery method disclosed in the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings.
The invention discloses a serial linear buffer zone and a sequence recovery method thereof, which can fully and effectively adjust a disturbed upstream product sequence to obtain a downstream release sequence with higher similarity to a target sequence.
The invention discloses a serial linear buffer zone, which comprises two sub-linear buffer zones and a middle transition parking space, wherein as shown in figure 1, the number L of lanes contained in each sub-linear buffer zone is the same, and the number W of parking spaces contained in each lane is also the same; according to the sequence of the upstream product flow, the two sub-linear buffer areas are respectively called an upstream buffer area and a downstream buffer area; the intermediate transition parking space is a product migration channel and a temporary storage place between the upstream buffer area and the downstream buffer area.
The invention discloses a sequence recovery method of a series linear buffer, as shown in figure 2, comprising the following steps:
s1, acquiring the total number T of products in the upstream sequence, and acquiring the position p of the upstream product i in the downstream target sequenceiWherein T is less than or equal to 2 lxw, i is 1, 2.
S2, setting the maximum iteration number S of local searchmaxInitializing the iteration number s of local search to be 1; sequentially appointing a sub-buffer area and a lane to be entered for each product i according to the entering rule and the sequence of reaching the serial linear buffer area, and constructing an initial product arrangement scheme A (0) in the serial linear buffer area as an optimal arrangement scheme Aopt(ii) a Sequentially releasing all products from the serial linear buffer area according to a release rule to obtain a downstream sequence corresponding to A (0) as an optimal recovery sequence Sdown(ii) a Wherein A isoptIn particular to an optimal arrangement scheme, SdownIn particular to an optimal recovery sequence;
the specific steps of specifying the entry rule to be entered into the sub-buffer for the product are as follows: before the downstream buffer zone is filled, an empty lane must be reserved in the upstream buffer zone to ensure that the product can smoothly enter the downstream buffer zone; when product i is at position p in the downstream target sequenceiWhen the number of the parking spaces is less than or equal to L multiplied by W, if the downstream buffer area has spare parking spaces, the product enters the downstream buffer area, otherwise, the product enters the upstream buffer area; when p isiWhen the speed is larger than L multiplied by W, if the upstream buffer area has empty parking spaces except an empty lane, the product enters the upstream buffer area, otherwise, the product enters the downstream buffer area.
The following rules are executed in the lane passing sequence for the product i which is appointed to enter the sub-buffer area, and the specific steps are as follows:
(a.1) randomly selecting a lane if i is 1;
(A.2) if product i and the last product i in a certain unfilled lane in the designated sub-buffer zoneendPosition p in the downstream target sequenceiAnd
Figure GDA0003233198030000071
satisfy the requirement of
Figure GDA0003233198030000072
The product enters the lane;
(A.3) if the designated sub-buffer area has a vacant lane, randomly selecting a vacant lane;
(A.4) if there is one (or more) unfilled lanes in the designated sub-buffer, its target sequence position of the last vehicle
Figure GDA0003233198030000073
Satisfy the requirement of
Figure GDA0003233198030000074
Selecting the lane (or
Figure GDA0003233198030000075
The smallest lane);
(A.5) if there is one (or more) unfilled lanes in the designated sub-buffer, its target sequence position of the last vehicle
Figure GDA0003233198030000076
Satisfy the requirement of
Figure GDA0003233198030000077
Selecting the lane (or
Figure GDA0003233198030000078
The smallest lane).
The release rule is used for continuously selecting products from the product candidate set to release until the serial linear buffer zone is emptied to obtain a downstream sequence; the method comprises the following specific steps:
(b.1) setting the release sequence number t of the product to 1;
(B.2) if a certain product i in the current product candidate set satisfies the condition: p is a radical ofiIf t, releasing the product i; otherwise, selecting the product with the minimum downstream target sequence position for release, and then updating the current product candidate set;
(b.3) moving to step (b.2) selecting the next release product until the tandem linear buffer is emptied by letting t be t + 1;
the product candidate set is composed of releasable products at the forefront of all non-empty lanes in the two sub-buffers.
S3, disturbing the current product arrangement scheme A (S-1) according to the exchange rule to obtain an S generation product arrangement scheme A (S);
the exchange rule is used for selecting two products in the linear buffer areas connected in series, exchanging the positions of the two products in the linear buffer areas, including the sub buffer areas and the lanes, and properly adjusting the parking sequence of the products in the related sub buffer areas and the lanes according to the first-in first-out principle, so as to obtain a new product arrangement scheme A(s);
when selecting a product to be exchanged, a product i is selected randomly first, and then another product m is selected according to the following method:
(C.1) if i is more than or equal to 1 and less than n, randomly selecting another product m on a different lane in the product set with the upstream sequence position of [1, n); wherein i is not equal to m, and n is the maximum position serial number of the end product of each lane of the upstream buffer in the upstream sequence;
(C.2) if n is less than or equal to i and less than or equal to T, randomly selecting another product m on a different lane in the product set positioned at the upstream sequence position of [ n, T ]; where i ≠ m.
S4, using ant colony algorithm to obtain the minimum total product displacement corresponding to the S generation product arrangement scheme A (S)As a global optimal downstream sequence Sopt(S) wherein Sopt(s) refers specifically to the optimal downstream sequence in the ant colony algorithm; the ant colony algorithm comprises the following specific steps:
s41, determining the activity area of the artificial ant as x, y belonging to [1, T ]]A constrained rectangular region; the ant climbs to a node with x being T from an initial position, namely, one iteration is completed, and path nodes passing along the path are sequentially P (1, y)1)，P(2，y2)，...，P(t，yt)，...，P(T，yT) Where yt e {1, 2,. T } corresponds to the upstream sequence position index of the tth product released from the serial linear buffer, T1, 2, …, T;
s42, setting and initializing algorithm parameters, including:
setting the number K of ants and the maximum iteration number r of the algorithmmaxLocal volatility ratio parameter rho of pheromonelPheromone global volatility ratio parameter ρgValue of [0, 1 ]]Parameter q between0A parameter alpha representing the importance degree of pheromone and parameters beta and gamma representing the importance degrees of other two heuristic information; wherein 0 < rhol＜1，0＜ρg＜1；
Initializing pheromone tau between any pair of adjacent products i and j in upstream sequenceijLet τ be at an initial timeij＝τ0In which τ is0Is a preset constant, i, j ═ 1, 2.., T; the iteration number r is initialized to 0; product candidate set Cand for each ant kkInitializing a set consisting of releasable products at the forefront end of each non-empty lane of an upstream buffer area and a downstream buffer area when the products are arranged according to an A(s) scheme, wherein K is 1, 2. The initial position of ant k is P (1, y)1)，y1Candidate set Cand for productkThe position serial number of the randomly selected product in the upstream sequence; releasing the selected products from the series linear buffer area, and updating a product candidate set Cand according to the head end product of the non-empty lanek(ii) a The current crawling step number is 1; initializing a current globally optimal downstream sequence Sopt(s) the total displacement of the product is plus infinity;
S43、in the t step of the r iteration, each ant k climbs to a node of x ═ t +1 from the node of x ═ t at the same time; calculating heuristic information eta associated with each possible position where x is t +1j：
Figure GDA0003233198030000081
Wherein, the product j belongs to the product candidate set Candk；
dj＝t+1-pj，|djL represents the total displacement increment of the product in the downstream sequence caused by the release of the selected product j, vjWhether or not product j appears at its downstream target sequence position pjWhen t is equal to pjWhen, vjTaking 0, otherwise, taking 1; beta is represented by djThe parameter of importance, γ, is a number representing vjA parameter of degree of importance;
calculating ant k slave node Pk(t，yt) In the climbing direction Pk(t+1，yt+1) Transition probability p of a nodek(yt，yt+1)：
Figure GDA0003233198030000082
Wherein
Figure GDA0003233198030000091
Indicating product ytAnd yt+1Pheromone concentration in between; y ist+1∈Candk；
Ant k climbs to destination node P at t stepk(t+1，yt+1) Indicating that ant k selectively releases product y in upstream sequencet+1The selection is carried out according to the following method:
when q is less than q0When it is selected
Figure GDA0003233198030000092
The product with the largest value; otherwise according to the transition probability pk(yt，yt+1) Determining candidate productsWherein q is in [0, 1 ]]Random numbers uniformly distributed among them;
updating product ytAnd yt+1Pheromone concentration between:
Figure GDA0003233198030000093
wherein
Figure GDA0003233198030000094
And
Figure GDA0003233198030000095
respectively representing the pheromone concentrations before and after updating;
when ant k crawls for one step, product candidate set Cand is releasedkAccording to the head end product of the non-empty lane, updating the product candidate set Candk；
Repeating the step S43 until T is T, completing an iteration, and recording the crawling path of each ant in the iteration;
s44, evaluating the downstream sequence of the iteration, including:
the ordinate of the path node passed by each ant crawling of the current iteration forms a downstream sequence, the total displacement of products of all K downstream sequences is calculated, and the downstream sequence with the minimum total displacement is selected as the optimal downstream sequence of the current iteration
Figure GDA0003233198030000096
If it is not
Figure GDA0003233198030000097
Is less than the current globally optimal downstream sequence Sopt(S) updating the total displacement of the productopt(s) is
Figure GDA0003233198030000098
S45, updating the current global optimal downstream sequence Sopt(s) pheromone concentration between each pair of adjacent productsDegree:
Figure GDA0003233198030000099
τijand τ'ijRespectively representing pheromone concentrations before and after update between products i and j, Z*For updated current globally optimal downstream sequence Sopt(s) a corresponding total displacement of the product;
let r be r +1, go to step S43 for the next iteration until the termination condition of the ant colony optimization algorithm is satisfied: r +1 ═ rmax。
The calculation formula of the total product displacement D in any downstream sequence Seq is as follows:
Figure GDA00032331980300000910
wherein d isiIs the position serial number i of the product i in the SeqseqPosition number p in downstream target sequence with product iiA difference of (i) di＝iseq-pi。
S5, if the global optimal downstream sequence Sopt(S) the total displacement of the product is less than the optimal recovery sequence SdownTotal displacement of the product in (1), will SdownIs updated to Sopt(s) optimizing the arrangement scheme AoptUpdated to A(s);
s6, judging whether the current iteration number meets the local search termination condition, namely S +1 > Smax(ii) a If not, let S be S +1, go to step S3 to perform the next search; if satisfied, the optimal recovery sequence SdownNamely the solved global optimal downstream sequence, the optimal arrangement scheme AoptIs a sum of SdownThe corresponding product arrangement scheme.
Examples
In this embodiment, a set of calculation examples is used to test the sequence recovery capability of the serial linear buffer proposed in the present invention. In the calculation example, the total number of vehicles in the series T is set to 30, 56, and 100. And respectively adopting three linear buffers connected in series to adjust the disturbed upstream sequence corresponding to different values of T. The three buffersThe buffer areas respectively comprise two sub-buffer areas connected in series, and the configuration of lanes and parking spaces of the buffer areas is respectively 5 multiplied by 3, 7 multiplied by 4 and 10 multiplied by 5. In addition, for each value of T, according to the parameter vT、Db、SrThe different combinations of (2) require that the 5 upstream sequences be randomly generated. Wherein v isTFor vehicles still at the target sequence position in the upstream sequence (i.e. satisfying i ═ p)i) The ratio of the number to T; dbFor lagging vehicles among the remaining vehicles (i.e. satisfying i > p)i) The number of the active carbon particles accounts for a proportion; srTo maximize lag (i.e., satisfy i-p)iMaximum) of the vehicle displacement amount and T-1. The combination of these three parameters represents the degree to which the initial planning sequence (i.e., the target sequence) is disturbed. v. ofTValues of 10% and 30%; dbThe values are 40% and 60%; srValues were 25% and 50%. The hybrid local search and ant colony optimization algorithm disclosed by the invention is written in a C + + language in a Microsoft Visual Studio environment and runs on a personal computer with a CPU (Central processing Unit) of 2.20GHz and a memory of 4.00 GB. Number of iterations s in the local search algorithmmax100; in the ant colony optimization algorithm: number of iterations rmax200, 5 and tau0＝1，ρl＝ρg＝0.2，q0＝0.5，α＝1，β＝2，γ＝4。
The sequence recovery method disclosed by the invention is used for controlling the serial linear buffer to recover the disordered upstream sequence in the example. In addition, for comparing the sequence recovery effect, the sequence recovery is also performed by using the conventional single linear buffer with the same capacity and combining with a similar sequence recovery method. The main differences from the sequence recovery method disclosed by the invention are as follows: when the vehicle enters the buffer area, the link of appointing to enter the sub buffer area is reduced; when searching the arrangement scheme of the vehicles in the buffer area, only two vehicles in different lanes need to be randomly selected, and then the lanes in which the two vehicles are respectively located are exchanged. Table 1 lists the average of the 5 example solution results for each parameter combination, i.e., the total displacement of all vehicles in the average downstream series. The calculation result shows that the serial linear buffer area provided by the invention can obviously reduce the total displacement of vehicles in an upstream sequence, the sequence recovery effect of the serial linear buffer area is obviously superior to that of the traditional single linear buffer area with the same capacity, and the promotion proportion can reach 44%. TABLE 1 sequence recovery results for two linear buffers
Figure GDA0003233198030000111

Claims (8)

1. A series linear buffer zone is characterized by comprising a series linear buffer zone, wherein the series linear buffer zone comprises two sub-linear buffer zones and a middle transition parking space, the number L of lanes contained in each sub-linear buffer zone is the same, and the number W of parking spaces contained in each lane is also the same; according to the sequence of the upstream product flow, the two sub-linear buffer areas are respectively called an upstream buffer area and a downstream buffer area; the intermediate transition parking space is a product migration channel and a temporary storage place between the upstream buffer area and the downstream buffer area.
2. A method for sequence recovery of a serial linear buffer according to claim 1, comprising the steps of:
s1, acquiring the total number T of products in the upstream sequence, and acquiring the position p of the upstream product i in the downstream target sequenceiWherein T is less than or equal to 2 lxw, i is 1, 2.
S2, setting the maximum iteration number S of local searchmaxInitializing the iteration number s of local search to be 1; sequentially appointing a sub-buffer area and a lane to be entered for each product i according to the entering rule and the sequence of reaching the serial linear buffer area, and constructing an initial product arrangement scheme A (0) in the serial linear buffer area as an optimal arrangement scheme Aopt(ii) a Sequentially releasing all products from the serial linear buffer area according to a release rule to obtain a downstream sequence corresponding to A (0) as an optimal recovery sequence Sdown；
S3, disturbing the current product arrangement scheme A (S-1) according to the exchange rule to obtain an S generation product arrangement scheme A (S);
s4, obtaining the product arrangement method corresponding to the S generation by using ant colony algorithmThe downstream sequence with the minimum total displacement of the products in case A (S) is used as the global optimal downstream sequence Sopt(s)；
S5, if the global optimal downstream sequence Sopt(S) the total displacement of the product is less than the optimal recovery sequence SdownTotal displacement of the product in (1), will SdownIs updated to Sopt(s) optimizing the arrangement scheme AoptUpdated to A(s);
s6, judging whether the current iteration number meets the local search termination condition, namely S +1 > Smax(ii) a If not, let S be S +1, go to step S3 to perform the next search; if satisfied, the optimal recovery sequence SdownNamely the solved global optimal downstream sequence, the optimal arrangement scheme AoptIs a sum of SdownThe corresponding product arrangement scheme.
3. The method for sequence recovery of serially connected linear buffers as claimed in claim 2, wherein in step S2, the rule for specifying the product to enter the sub-buffers is: in order to ensure that the product can smoothly enter the downstream buffer zone, an empty lane must be reserved in the upstream buffer zone before the downstream buffer zone is filled; when product i is at position p in the downstream target sequenceiWhen the number of the parking spaces is less than or equal to L multiplied by W, if the downstream buffer area has spare parking spaces, the product enters the downstream buffer area, otherwise, the product enters the upstream buffer area; when p isiWhen the speed is larger than L multiplied by W, if the upstream buffer area has empty parking spaces except one empty lane, the product enters the upstream buffer area, otherwise, the product enters the downstream buffer area.
4. The method for sequence recovery of serially connected linear buffers as claimed in claim 2, wherein in step S2, the following rules are executed in the order of entering lane selection for product i designated to enter the sub-buffer:
(a.1) randomly selecting a lane if i is 1;
(A.2) if product i and the last product i in a certain unfilled lane in the designated sub-buffer zoneendPosition p in the downstream target sequenceiAnd
Figure FDA0003233198020000021
satisfy the requirement of
Figure FDA0003233198020000022
The product enters the lane;
(A.3) if the designated sub-buffer area has a vacant lane, randomly selecting a vacant lane;
(A.4) if the designated sub-buffer exists an unfilled lane, and
Figure FDA0003233198020000023
if the number of the unfilled lanes is 1, the product enters the lane; if the number of the unfilled lanes is more than 1, the product enters
Figure FDA0003233198020000024
The smallest of the lanes;
(A.5) if the designated sub-buffer exists an unfilled lane, and
Figure FDA0003233198020000025
if the number of the unfilled lanes is 1, the product enters the lane; if the number of the unfilled lanes is more than 1, the product enters
Figure FDA0003233198020000026
The smallest lane.
5. The method for sequence recovery of serially connected linear buffers as claimed in claim 2, wherein the releasing rule in step S2 is used to continuously select product releases from the candidate set of products until the serially connected linear buffers are empty, resulting in a downstream sequence; the method comprises the following specific steps:
(b.1) setting the release sequence number t of the product to 1;
(B.2) if a certain product i in the current product candidate set satisfies the condition: p is a radical ofiIf t, releasing the product i; otherwise, selecting the product with the minimum downstream target sequence position for release, and then updating the current product candidate set;
(b.3) moving to step (b.2) selecting the next release product until the tandem linear buffer is emptied by letting t be t + 1;
the product candidate set is composed of releasable products at the forefront of all non-empty lanes in the two sub-buffers.
6. The method for restoring sequence of serially connected linear buffers according to claim 2, wherein in step S3, the switching rule is used to select two products in the serially connected linear buffers, switch their respective positions, including their sub-buffers and lanes, and adjust the parking sequence of the products in the sub-buffers and lanes according to the first-in first-out principle, so as to obtain a new product arrangement scheme a (S);
when selecting a product to be exchanged, a product i is selected randomly first, and then another product m is selected according to the following method:
(C.1) if i is more than or equal to 1 and less than n, randomly selecting another product m on a different lane in the product set with the upstream sequence position of [1, n); wherein i is not equal to m, and n is the maximum position serial number of the end product of each lane of the upstream buffer in the upstream sequence;
(C.2) if n is less than or equal to i and less than or equal to T, randomly selecting another product m on a different lane in the product set positioned at the upstream sequence position of [ n, T ]; where i ≠ m.
7. The method for sequence recovery of serially connected linear buffers as claimed in claim 2, wherein the ant colony algorithm in step S4 includes the following steps:
s41, determining the activity area of the artificial ant as x, y belonging to [1, T ]]A constrained rectangular region; the ant climbs to a node with x being T from an initial position, namely, one iteration is completed, and path nodes passing along the path are sequentially P (1, y)1)，P(2，y2)，...，P(t，yt)，...，P(T，yT) Wherein y istE {1, 2,. T } corresponds to the upstream sequence position number of the tth product released from the tandem linear buffer, T1, 2, …, T;
s42, setting and initializing algorithm parameters, including:
setting the number K of ants and the maximum iteration number r of the algorithmmaxLocal volatility ratio parameter rho of pheromonelPheromone global volatility ratio parameter ρgValue of [0, 1 ]]Parameter q between0A parameter alpha representing the importance degree of pheromone and parameters beta and gamma representing the importance degrees of other two heuristic information; wherein 0 < rhol＜1，0＜ρg＜1；
Initializing pheromone tau between any pair of adjacent products i and j in upstream sequenceijLet τ be at an initial timeij＝τ0In which τ is0Is a preset constant, i, j ═ 1, 2.., T; the iteration number r is initialized to 0; product candidate set Cand for each ant kkInitializing a set consisting of releasable products at the forefront end of each non-empty lane of an upstream buffer area and a downstream buffer area when the products are arranged according to an A(s) scheme, wherein K is 1, 2. The initial position of ant k is P (1, y)1)，y1Candidate set Cand for productkThe position serial number of the randomly selected product in the upstream sequence; releasing the selected products from the series linear buffer area, and updating a product candidate set Cand according to the head end product of the non-empty lanek(ii) a The current crawling step number is 1; initializing a globally optimal downstream sequence Sopt(s) the total displacement of the product is plus infinity;
s43, in the t-th step of the r-th iteration, each ant k climbs from the node where x is t to the node where x is t + 1; calculating heuristic information eta associated with each possible position where x is t +1j：
Figure FDA0003233198020000031
Wherein, the product j belongs to the product candidate set Candk；
dj＝t+1-pj，|djL represents the total displacement increment of the product in the downstream sequence caused by the release of the selected product j, vjWhether or not product j appears at its downstream target sequence position pjWhen t is equal to pjWhen, vjTaking 0, otherwise, taking 1; beta is represented by djThe parameter of importance, γ, is a number representing vjA parameter of degree of importance;
calculating ant k slave node Pk(t，yt) In the climbing direction Pk(t+1，yt+1) Transition probability p of a nodek(yt，yt+1)：
Figure FDA0003233198020000032
Wherein
Figure FDA0003233198020000033
Indicating product ytAnd yt+1Pheromone concentration in between; y ist+1∈Candk；
Ant k climbs to destination node P at t stepk(t+1，yt+1) Indicating that ant k selectively releases product y in upstream sequencet+1The selection is carried out according to the following method:
when q is less than q0When it is selected
Figure FDA0003233198020000041
The product with the largest value; otherwise according to the transition probability pk(yt，yt+1) Determining candidate products, wherein q is [0, 1 ]]Random numbers uniformly distributed among them;
updating product ytAnd yt+1Pheromone concentration between:
Figure FDA0003233198020000042
wherein
Figure FDA0003233198020000043
And
Figure FDA0003233198020000044
respectively representing updatesThe pheromone concentrations before and after;
when ant k crawls for one step, product candidate set Cand is releasedkAccording to the head end product of the non-empty lane, updating the product candidate set Candk；
Repeating the step S43 until T is T, completing an iteration, and recording the crawling path of each ant in the iteration;
s44, evaluating the downstream sequence of the iteration, including:
the ordinate of the path node passed by each ant crawling of the current iteration forms a downstream sequence, the total displacement of products of all K downstream sequences is calculated, and the downstream sequence with the minimum total displacement is selected as the optimal downstream sequence of the current iteration
Figure FDA0003233198020000045
If it is not
Figure FDA0003233198020000046
Is less than the global optimal downstream sequence Sopt(S) updating the total displacement of the productopt(s) is
Figure FDA0003233198020000047
S45, updating the global optimal downstream sequence SoptPheromone concentration between each pair of adjacent products in(s):
Figure FDA0003233198020000048
τijand τ'ijRespectively representing pheromone concentrations before and after update between products i and j, Z*For a globally optimal downstream sequence Sopt(s) a corresponding total displacement of the product;
let r be r +1, go to step S43 for the next iteration until the termination condition of the ant colony optimization algorithm is satisfied: r +1 ═ rmax。
8. The method for sequence recovery of serially connected linear buffers as claimed in claim 7, wherein the calculation formula of the total displacement D of the products in any downstream sequence Seq is:
Figure FDA0003233198020000049
wherein d isiIs the position serial number i of the product i in the SeqseqPosition number p in downstream target sequence with product iiA difference of (i) di＝iseq-pi。
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