CN111160698B - Method and device for evaluating performance of multi-layer shuttle system - Google Patents

Abstract

The present disclosure provides a method and device for evaluating the performance of a multi-layer shuttle vehicle system. Among them, a method for evaluating the performance of a multi-layer shuttle vehicle system includes establishing an open-loop queuing network model of a re-loading vehicle system and an open-loop queuing network model of a loop line system respectively; Calculate the throughput and order completion cycle corresponding to the corresponding open-loop queuing network model respectively; under the condition that the number of layers and the number of lanes are constant, according to the throughput and order completion cycle corresponding to the corresponding open-loop queuing network model, evaluate the optimal multi-storey shuttle system.

Description

A method and device for evaluating the performance of a multi-layer shuttle system

technical field

The present disclosure belongs to the field of shuttle car scheme recommendation, and in particular relates to a method and device for evaluating the performance of a multi-layer shuttle car system.

Background technique

The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

With the rapid development of e-commerce, the orders of logistics distribution centers show a trend of multiple varieties, small batches and fast response, which puts forward higher requirements for the picking system. Multi-layer shuttle system (Automated Vehicle Storage/Retrieval System, AVS/RS) has been widely used in recent years due to its high efficiency and accuracy. Usually, the multi-level shuttle system is composed of an aisle shuttle vehicle (referred to as an aisle vehicle) and a hoist, but this structural system needs to be combined after the picking is completed, resulting in a large number of operators and a long picking cycle. With the continuous expansion of the scale of e-commerce enterprises, the variety of goods they sell is gradually increasing. Avoid picking and combining orders.

The inventor found that the current problem with the performance evaluation method of the multi-layer shuttle vehicle system is: two types of AVS/RS based on the transfer vehicle and based on the circular conveyor line, both of which can realize the fast picking of goods, but the system throughput is limited. There are differences in quantity and order completion cycle, which makes enterprise decision makers have difficulties in system selection.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present disclosure provides a method and device for evaluating the performance of a multi-layer shuttle vehicle system, which reduces the initial decision-making cost of the enterprise decision-making layer, reduces the input cost of manpower and material resources, and improves the accuracy of the multi-layer shuttle vehicle system evaluation. .

In order to achieve the above object, the present disclosure adopts the following technical solutions:

A first aspect of the present disclosure provides a method for evaluating the performance of a multi-level shuttle system, including:

The open-loop queuing network model of the transshipment vehicle system and the open-loop queuing network model of the loop line system are established respectively;

Based on the open-loop queuing network model of the transshipment vehicle system and the open-loop queuing network model of the loop line system, the throughput and order completion cycle corresponding to the corresponding open-loop queuing network model are calculated respectively;

When the number of layers and lanes are fixed, the optimal multi-layer shuttle system is evaluated according to the throughput and order completion cycle corresponding to the corresponding open-loop queuing network model.

A second aspect of the present disclosure provides a device for evaluating the performance of a multi-level shuttle vehicle system, which includes:

an open-loop queuing network model establishment module, which is used to establish the open-loop queuing network model of the transshipment vehicle system and the open-loop queuing network model of the loop line system respectively;

A performance parameter calculation module, which is used to calculate the throughput and order completion period corresponding to the corresponding open-loop queuing network model based on the open-loop queuing network model of the transshipment vehicle system and the open-loop queuing network model of the loop line system respectively;

The optimal multi-layer shuttle system evaluation module is used to evaluate the optimal multi-layer shuttle according to the throughput and order completion cycle corresponding to the corresponding open-loop queuing network model under the condition that the number of layers and the number of lanes are constant. car system.

A third aspect of the present disclosure provides a computer-readable storage medium on which a computer program is stored, and when the program is executed by a processor, implements the steps in the method for evaluating the performance of a multi-level shuttle system as described above.

A fourth aspect of the present disclosure provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, the processor implementing the multi-layer as described above when the processor executes the program Steps in a method for evaluating the performance of a shuttle system.

The beneficial effects of the present disclosure are:

The present disclosure first establishes the open-loop queuing network models of the two systems, and then solves the system throughput and order completion period. Under the condition that the number of layers and the number of lanes are constant, the throughput and order corresponding to the corresponding open-loop queuing network models are calculated. After completing the cycle, the optimal multi-layer shuttle system is evaluated, which reduces the initial decision-making cost of the enterprise decision-making layer, reduces the input cost of manpower and material resources, and improves the accuracy of the multi-layer shuttle system evaluation.

Description of drawings

The accompanying drawings that constitute a part of the present disclosure are used to provide further understanding of the present disclosure, and the exemplary embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation of the present disclosure.

1 is a flowchart of a method for evaluating the performance of a multi-layer shuttle vehicle system provided by an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of a transfer vehicle system provided by an embodiment of the present disclosure;

3 is a schematic diagram of a loop line system provided by an embodiment of the present disclosure;

FIG. 4 is an open-loop queuing network model of a reloading vehicle system provided by an embodiment of the present disclosure;

5 is an open-loop queuing network model of a loop line system provided by an embodiment of the present disclosure;

Fig. 6(a) is an acceleration change diagram of a roadway vehicle provided by an embodiment of the present disclosure;

Fig. 6(b) is a speed change diagram of a roadway vehicle provided by an embodiment of the present disclosure;

FIG. 7 is a comparison result of throughput between a transfer vehicle system and a loop system provided by an embodiment of the present disclosure;

FIG. 8( a ) is the experimental result of the operating time difference between the undercarriage system with the number of lanes 2 to 6 and the number of floors 3 to 11 and the loop system provided by the embodiment of the present disclosure;

Fig. 8(b) is the experimental result of the difference in operating time between the undercarriage system and the loop system provided by the embodiment of the present disclosure;

FIG. 8( c ) is an experimental result of the difference in operating time between the undercarriage system and the loop system provided by the embodiment of the present disclosure;

Fig. 8(d) is the experimental result of the difference in operating time between the transfer vehicle system under the lanes 7-10, the layers 12-20, and the loop system provided by the embodiment of the present disclosure;

FIG. 9 is a schematic structural diagram of an apparatus for evaluating the performance of a multi-layer shuttle vehicle system provided by an embodiment of the present disclosure.

Detailed ways

The present disclosure will be further described below with reference to the accompanying drawings and embodiments.

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present disclosure. Unless otherwise defined, all technical and scientific terms used in the examples have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

It should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural as well, furthermore, it is to be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates that There are features, steps, operations, devices, components and/or combinations thereof.

Terminology Explanation:

(1) Reloading vehicle system

The reloading vehicle system takes the material box as the storage unit, and is composed of roadway vehicles, reloading vehicles, elevators, picking tables and conveying buffer areas. Each floor and each roadway is equipped with one roadway car, each floor is equipped with one transfer car, and every two hoists (respectively responsible for outbound and inbound) correspond to a picking table. The roadway car is responsible for the horizontal movement of the material box in a single roadway, the transfer car is responsible for the horizontal movement between different roadways, the hoist is responsible for the vertical movement between different layers, and the conveying buffer area is responsible for temporarily storing the material box in the process of entering and leaving the warehouse. The top view of the system and the in-out process are shown in Figure 2, where the dotted line is the in-warehousing process, and the solid line is the out-of-warehouse process.

When the system performs the outbound task, firstly, the material box is retrieved by the roadway fork and transported to the corresponding outbound buffer area; then the reloading vehicle transports it to the corresponding outbound buffer area, and then the elevator transports the material box to the corresponding outbound buffer area. Corresponding to the outbound buffer area; finally, the picking is completed at the picking table. When the system performs the warehousing task, the material box first enters the warehousing buffer area from the picking table, and the hoist transports the material box to the corresponding warehousing buffer area; then the reloading vehicle transports it to the corresponding warehousing buffer area; The truck transports the material box to the designated location.

(2) Loop system

The loop line system takes the material box as the storage unit, and consists of the roadway car, the hoist, the circular conveying line, the picking table and the conveying buffer area. Each lane is equipped with one lane car, and each lane corresponds to two hoists (respectively responsible for outbound and inbound), and the circular conveyor line is only arranged on the first floor, responsible for the transport of the bins between different hoists and picking tables. delivery. The top view of the system and the in-out process are shown in Figure 3, where the dotted line represents the in-warehousing process, and the solid line represents the out-of-warehouse process.

When the system performs the outbound task, firstly, the material box is retrieved by the roadway fork, transported to the corresponding outbound buffer area, and then transported to the corresponding outbound buffer area by the hoist, and then enters the circular conveyor line, and finally the material box is transported to the corresponding outbound buffer area by the elevator. Enter the corresponding picking table with the circular conveyor line to complete the picking. When the system performs the warehousing task, the material box first enters the warehousing buffer area from the picking table, and the material box is transported to the corresponding warehousing buffer area by the circular conveying line; then it is transported to the corresponding warehousing buffer area by the elevator; The roadway truck transports the material box to the designated location.

Example 1

As shown in FIG. 1 , this embodiment provides a method for evaluating the performance of a multi-layer shuttle vehicle system, which includes:

Step 1: Establish the open-loop queuing network model of the reloading vehicle system and the open-loop queuing network model of the loop system respectively.

The system variables of this embodiment are defined as follows:

In order to simplify the model, the following assumptions are put forward for AVS/RS in this embodiment: (1) When the material box is returned to the warehouse, follow the random cargo space allocation strategy; (2) The movable system equipment is the docking point of roadway vehicles, transfer vehicles and hoists (3) The order obeys the principle of first-come, first-served; (4) The order arrival obeys Poisson distribution; (5) The service time of the picking table is constant, and the service time of the mobile system equipment follows the general distribution; (6) The capacity of the conveying buffer area is large enough; (7) One material box only stores one kind of commodity, and one kind of commodity is only stored in one material box.

Based on the above assumptions, an open-loop queuing network model of the reloading vehicle system is established, as shown in Figure 4. When the system performs the outbound task, the order arrival rate λ is the input of the system, and it is also the input of the roadway car; the output of the roadway car is the input of the reloading car; the output of the reloading car is the input of lifting; the output of the elevator is the input of the picking table enter. On the contrary, when the system performs the warehousing task, the output of the picking table is the input of the hoist; the output of the hoist is the input of the reloading car; the output of the reloading car is the input of the roadway car.

Since the arrival of orders obeys Poisson distribution, the service time of roadway vehicles, transfer vehicles and elevators obeys general distribution, and the service time of picking tables obeys uniform distribution. Form the M/G/1 queue.

Based on the above assumptions, an open-loop queuing network model of the ring line system is established, as shown in Figure 5. When the system performs the outbound task, the order arrival rate λ is the input of the system and the input of the roadway car; the output of the roadway car is the input of the hoist; the output of the hoist is the input of the ring conveyor line; the output of the ring conveyor line is The input of the pick table. Conversely, when the system performs the warehousing task, the output of the picking table is the input of the circular conveyor line; the output of the circular conveyor line is the input of the hoist; the output of the hoist is the input of the roadway car.

Similar to the transfer car system, in the queuing network model of the loop system, the roadway car, the hoist, the loop conveying line, the picking table and the corresponding conveying buffer area constitute the M/G/1 queue.

Step 2: Calculate the throughput and order completion period corresponding to the corresponding open-loop queuing network model based on the open-loop queuing network model of the reloading vehicle system and the open-loop queuing network model of the loop line system respectively;

AVS/RS system performance includes throughput and order fulfillment cycles. Throughput refers to the order processing volume of the system per unit time, and the order completion cycle refers to the time from the start of the order out of the warehouse to the end of the picking.

It can be seen from the system workflow that the system performance is jointly determined by the outbound process and the inbound process, and the system inbound process is completely opposite to the outbound process. Therefore, this embodiment only considers the system throughput and order completion cycle under the outbound process. The comparison results of the actual throughput and the order completion period of the two systems are consistent with the results of this embodiment.

The system non-decision variables are defined as follows:

The system decision variables are defined as follows:

(a1) Throughput of the reloading vehicle system

The throughput of the transfer vehicle system is the minimum of the throughputs of the four types of equipment, namely the roadway car, the transfer car, the elevator and the picking table, namely

τ _m1 =min(τ _AS ,τ _CAS ,τ _L ,τ _W ) (1)

in

(如公式6所示)；(2)将料箱从第i列运送至输送缓存区行走的时间

(如公式7所示)；(3)取、放料箱的时间t_p1。根据巷道车的行驶距离和速度变化情况，分两种情况考虑，第一种情况为巷道车在行走时间t内到达最高速，第二种情况为巷道车未到达最高速，分别如图6(a)和图6(b)所示，其中a_AS和

分别为巷道车的加速度和最大速度。The service time of the roadway car includes three parts: (1) From the conveying buffer area (defining the conveying buffer area as the 0th column) or any column of the cargo position, collectively referred to as the j (0≤j≤c) column, to the i-th ( 1≤i≤c) The walking time of the reclaiming box

(as shown in formula 6); (2) the time for transporting the material box from the i-th column to the conveying buffer area

(as shown in formula 7); (3) the time t _p1 for taking and discharging the bin. According to the driving distance and speed changes of the roadway vehicle, two cases are considered. The first case is that the roadway vehicle reaches the highest speed within the travel time t, and the second case is that the roadway vehicle does not reach the highest speed, as shown in Figure 6 ( a) and Figure 6(b), where a _AS and

are the acceleration and maximum speed of the roadway vehicle, respectively.

The time for the roadway truck to transport the material box from the i-th column to the conveying buffer area is:

The value of n _d in formula (7) is the same as that in formula (6 ₎ .

The time for the roadway car to take the material box from the i-th row is

The average service time for roadway cars is

The service time of the reloading vehicle includes: (1) The time t i from the stop point, that is, the i-th (1≤i≤l) elevator to the j-th (1≤j≤a) aisle conveying buffer area for the reclaiming box travel time t _{i ,j} (as shown in Equation 10); (2) the time t _j,k (as shown in Equation 11) when the material box is transported to the k (1≤k≤l) hoist travel time; (3) take, The time t _p2 for discharging the bin.

分别为转载车的加速度和最大速度，d_i,j和d_j,k分别为转载车从第i个提升机到第j个巷道输送缓存区取料箱的距离和从第j个巷道输送缓存区到第k个提升机送料箱的距离。In formulas (10) and (11), a _CAS and

are the acceleration and maximum speed of the reloading vehicle, respectively, d _i,j and d _j,k are the distance from the ith hoist to the reclaiming box in the jth lane conveying buffer area and the conveying buffer from the jth lane respectively. The distance from the zone to the kth elevator feed box.

The time for the reloading vehicle to leave the storage area of the j-th roadway to take the material box is:

(1≤i≤l, 1≤j≤a, 1≤k≤l)

The average service time of the reloading car is

(如公式14所示)；(2)从第i层到第1层送料箱行走的时间

(3)取、放料箱的时间t_p3。The service time of the hoist includes: (1) The time from the first layer to the i-th layer (1≤i≤t) for the reclaiming box to travel

(as shown in Equation 14); (2) the travel time from the i-th layer to the first-layer feeding box

(3) The time t _p3 for taking and discharging the bin.

分别为提升机的加速度和最大速度，n_l为提升机达到最大速度时需要的层数且

In formula (14), a _L and

are the acceleration and maximum speed of the hoist, respectively, n _l is the number of layers required when the hoist reaches the maximum speed and

The time that the elevator takes from the i-th layer of the material box is

The average service time of the hoist is

(a2) Order completion cycle of the reloading vehicle system

The order completion cycle of the transfer vehicle system is the sum of the service time and waiting time of the service organization (roadway car, transfer car, elevator and picking table), namely

Since the roadway car, the transfer car, the elevator, the picking table and their respective conveying buffer areas constitute the M/G/1 queuing model, the Pollaczek-Khintchine formula can be used to obtain the captain of the service organization. and waiting time, as shown in equations (18) and (19), respectively.

其中λ为订单到达率；μ为单位时间内完成的订单数，其值为平均服务时间的倒数；t为每个服务机构单个订单完成时间(巷道车、转载车、提升机、拣选台对应值分别为

E(t)为服务机构平均服务时间，P_k为每个订单到达的概率，k为到达系统的订单编号。In formulas (18) and (19), ρ and σ ² are the utilization rate and service time variance of service organizations (roadway vehicles, transfer vehicles, hoists, annular conveying lines and picking tables), respectively, ρ=λμ,

Among them, λ is the order arrival rate; μ is the number of completed orders per unit time, which is the reciprocal of the average service time; t is the completion time of a single order for each service organization (the corresponding value of roadway vehicles, transfer vehicles, elevators, and picking tables) respectively

E(t) is the average service time of the service organization, P _k is the probability of each order arriving, and k is the order number arriving in the system.

Applying equation (19) to the reloading vehicle system, we can get:

The time for the material box to wait for the service of the roadway car is

和

分别为第i层j巷道巷道车取料箱的概率、订单到达率、利用率和服务时间方差，由于本实施例中的AS/RS遵循随机存取原则，因此In formula (20),

and

are the probability, order arrival rate, utilization rate, and service time variance of the vehicle reclaiming box in the i-th layer j roadway, respectively. Since the AS/RS in this embodiment follows the random access principle, so

The time for the material box to wait for the transfer car service is

和

分别为第i层转载车取料箱的概率、订单到达率、利用率和服务时间方差，由于本实施例中的AS/RS遵循随机存取原则，因此In formula (21),

and

are the probability, order arrival rate, utilization rate and service time variance of the reloading box of the i-th layer, respectively. Since the AS/RS in this embodiment follows the random access principle, so

The time for the material box to wait for the elevator service is

和

分别为第k个提升机取料箱的概率、订单到达率、利用率和服务时间方差，由于本实施例中的AS/RS遵循随机存取原则，因此In formula (22),

and

are the probability, order arrival rate, utilization rate, and service time variance of the k-th elevator reclaiming box, respectively. Since the AS/RS in this embodiment follows the random access principle, so

The time for the bin to wait for the picker to be serviced is

和

分别为第m个拣选台进行拣选作业的概率、订单到达率和利用率，由于本实施例中的AS/RS遵循随机存取原则，因此

In formula (23),

and

are the probability, order arrival rate, and utilization rate of the picking operation performed by the mth picking table, respectively. Since the AS/RS in this embodiment follows the random access principle, so

(b1) Throughput of loop system

The throughput of the loop system is the minimum of the throughput of the road car, hoist, loop conveyor and picking table, i.e.

τ _m2 =min(τ _AS ,τ _L ,τ _R ,τ _W ) (24)

In formula (24), the solution of τ _AS , τ _L , and τ _W is the same as that of the transfer vehicle system.

The throughput of the loop conveyor line is

(b2) Order Completion Cycle of Ring Line System

The order completion cycle of the loop system is the sum of the service time and waiting time of the roadway car, hoist, loop conveyor line and picking table, namely

的求解In the formula, since

solution

和

即可。The same as the transfer car system, so only need to solve

and

That's it.

The walking time of the material box from the ith (1≤i≤l) elevator to the jth (1≤j≤w) picking table is

In formula (27), l _i,j is the distance from the i-th outbound elevator port to the j-th picking table port on the circular conveyor line.

The service time of the circular conveyor line for a single material box is

The average time for a bin to wait for service on an endless conveyor is

In formula (29), λ _R and ρ _R are the order arrival rate and utilization rate of the annular conveying line, respectively, that is, λ _R =λ,

In order to verify the correctness of the models of the reloading vehicle system and the loop system, the two systems are simulated respectively. The 6-day order data of an e-commerce company in 2018 is randomly selected, the order arrival time is fitted to a Poisson distribution, and the simulation is performed by Flexsim software. Assuming that both the reloading vehicle system and the loop system have 6 lanes, 80 columns, 10 floors, 6 out/in warehousing elevators, and 6 picking tables, other system parameters are shown in Table 1.

Table 1 System parameters

According to the system parameters, the simulation model of the reloading vehicle system is established, and the solution results of the queuing network model of the system and the simulation results are compared and analyzed, as shown in Table 2.

Table 2 Comparison between the queuing network model of the reloading vehicle system and the simulation results

In the 6 groups of experiments, the maximum throughput of the queuing network model is 2068 boxes/hour, so when the order arrival rate is not greater than 2068 boxes/hour, the actual throughput of the system is equal to the order arrival rate, and vice versa is equal to the maximum throughput. In the first five groups of experiments, the queuing network model is the same as the actual throughput in the simulation results; in the sixth group of experiments, the order arrival rate reaches the maximum throughput of the system, and the throughput difference between the two is only 5.3%, so it can be considered that queuing The throughput of the network model is basically consistent with the simulation results. At the same time, the difference in the order completion cycle between the two is 5.0% to 6.1%, and the variance is 5.60. It can be considered that the order completion cycle of the two is the same.

In summary, there is no significant difference between the system queuing network model and the simulation results.

Step 3: Evaluate the optimal multi-layer shuttle system according to the throughput and order completion cycle corresponding to the corresponding open-loop queuing network model when the number of layers and lanes are constant.

According to the system parameters, the simulation model of the loop system is established, and the solution results of the queuing network model of the system and the simulation results are compared and analyzed, as shown in Table 3.

In the 6 sets of experiments, the maximum throughput of the queuing network model is 1800 boxes/hour, so when the order arrival rate is not greater than 1800 boxes/hour, the actual throughput of the system is equal to the order arrival rate, and vice versa is equal to the maximum throughput. In the first five groups of experiments, the queuing network model is the same as the actual throughput in the simulation results; in the sixth group of experiments, the order arrival rate reaches the maximum throughput of the system, and the throughput difference between the two is only 6.7%, so it can be considered that queuing The throughput of the network model is basically consistent with the simulation results. At the same time, the difference in the order completion cycle between the two is 4.2% to 6.6%, and the variance is 4.96. It can be considered that the order completion cycle of the two is the same.

Table 3 Comparison between the queuing network model of the ring line system and the simulation results

In summary, there is no significant difference between the system queuing network model and the simulation results.

Throughput and order completion cycle analysis are carried out for the transfer vehicle system and the loop system, and the two systems are compared.

Throughput comparative analysis:

Let τ ^* =min(τ _AS ,τ _L ,τ _W ), then the throughput of the two systems can be expressed as τ _m1 =min(τ ^* ,τ _CAS ) and τ _m2 =min(τ ^* ,τ _R ). When τ _CAS <τ _R , then τ _m1 ≤τ _m2 is established; on the contrary, when τ _CAS >τ _R , then τ _m1 ≥τ _m2 is established, so the throughput comparison problem of the two systems can be transformed into a transfer vehicle and a circular conveyor line Throughput comparison problem. From the mathematical solution model of τ _CAS and τ _R , it can be known that under the condition of a certain roadway width, τ _CAS is related to the number of shelf layers and roadways; while τ _R is only related to the speed of the circular conveyor line.

In the loop line system, when the speed of the loop conveyor line is a fixed value of 0.5 m/s, the throughput of the loop conveyor line can be obtained as 1800 boxes/hour. In the transshipment vehicle system, the number of shelf layers is increased from 3 to 20, and the number of lanes is increased from 2 to 10. According to the mathematical model of τ _CAS , τ _CAS can obtain 162 kinds of results. The comparison results of 162 kinds of τ _CAS and τ _R are shown in Figure 7, where the circles indicate τ _CAS <τ _R , that is, τ _m1 ≤τ _m2 ; the asterisks indicate that τ _CAS >τ _R , that is, τ _m1 ≥τ _m2 .

It can be seen from Figure 7 that:

(1) When the number of roadways is fixed and the number of layers changes from 3 to 20, τ _CAS presents an upward trend; the smaller the number of roadways, the more obvious the upward trend of τ _CAS with the increase of the number of layers. When the number of layers is fixed and the number of roadways changes from 2 to 10, τ _CAS presents a downward trend; the greater the number of layers, the more obvious the downward trend of τ _CAS with the increase of the number of roadways.

(2) When the number of layers is [3,5], τ _CAS is between (465, 1547), τ _m1 is less than or equal to τ _m2 , and the loop system is better; when the number of layers increases from 6 to 11, τ _m1 ≤τ The proportion of _m2 gradually decreases; when the number of layers is [12, 20], τ _CAS is between (1863, 6189), τ _m1 is greater than τ _m2 , and the reloading vehicle system is better. Therefore, the lower the number of layers, the greater the advantage of the loop system; the higher the number of layers, the greater the advantage of the reloading vehicle system.

(3) When the number of lanes changes from 2 to 10, with the increase of the number of lanes, the proportion of τ _m1 ≤ τ _m2 gradually increases, and the advantage of the loop system becomes larger and larger. Therefore, when the number of roadways is small, the transfer vehicle system is better; when the number of roadways is large, the loop system is better.

因此可将两系统订单完成周期的比较问题转化为转载车和环形输送线作业时间(服务时间和等待时间之和)比较问题。由转载车和环形输送线作业时间的数学求解模型可知，t_m1与t_m2的差值与订单到达率、货架层数、巷道数有关。The difference between the order completion period of the reloading vehicle system and the loop line system is

Therefore, the comparison problem of the order completion cycle of the two systems can be transformed into the comparison problem of the operation time (sum of service time and waiting time) of the transfer vehicle and the circular conveyor line. From the mathematical solution model of the operation time of the reloading vehicle and the circular conveyor line, it can be known that the difference between t _m1 and t _m2 is related to the order arrival rate, the number of shelf layers, and the number of lanes.

When the order arrival rate increases from 0 to 2000 (the change interval is 500) orders/hour, the number of lanes increases from 2 to 10, and the number of layers increases from 3 to 20, calculate t _m1 -t _m2 . If t _m1 -t _m2 <0, it is represented by an asterisk in Figure 8; otherwise, it is represented by a circle, and 960 pieces of data are obtained through experiments, and the experimental results are shown in Figures 8(a) to 8(d).

Analysis of Figures 8(a) to 8(d) shows that:

(1) The proportions of data with t _m1 >t _m2 in the four graphs 8(a) to 8(d) are: 40%, 40.74%, 0% and 4.17%, respectively. Among them, the ratios of 8(a) and 8(b) are similar, and the ratios of 8(c) and 8(d) are similar.

(2) Comparing 8(a) and 8(c), it can be seen that when the number of lanes and the order arrival rate are constant, the more layers, the shorter the order completion cycle of the reloading vehicle system. Comparing 8(b) and 8(d) leads to the same conclusion.

(3) Comparing 8(a) and 8(b), we can see that when the number of floors and lanes is constant, the greater the order arrival rate, the shorter the order completion cycle of the loop system.

(4) Comparing 8(a) and 8(b), 8(c) and 8(d) respectively, we can see that when the number of floors and the order arrival rate are constant, the effect of the number of lanes on the operating time of the two systems is shown. It is not obvious, this is because the number of lanes has an influence on the operation time of the transfer vehicle and the operation time of the circular conveyor line, and the difference in the degree of influence is small.

In this embodiment, the open-loop queuing network models of the two systems are first established, and then the system throughput and order completion period are calculated. Under the condition that the number of layers and the number of lanes are constant, the corresponding throughput and In the order completion cycle, the optimal multi-storey shuttle system is evaluated, which reduces the initial decision-making cost of the enterprise decision-making layer, reduces the input cost of manpower and material resources, and improves the accuracy of the multi-storey shuttle system evaluation.

Example 2

As shown in FIG. 9 , the present embodiment provides a device for evaluating the performance of a multi-layer shuttle vehicle system, which includes:

(1) A module for establishing an open-loop queuing network model, which is used to respectively establish an open-loop queuing network model of a transshipment vehicle system and an open-loop queuing network model of a loop line system;

Specifically, in the open-loop queuing network model establishment module, the open-loop queuing network model of the reloading vehicle system and the open-loop queuing network model of the loop line system are both constructed under the following assumptions:

When the material box is returned to the warehouse, follow the random location allocation strategy;

The stop point of the movable system equipment, that is, the roadway vehicle, the transfer vehicle and the hoist, is the completion point of the last entry and exit operation;

Orders are subject to the principle of first come, first served;

Order arrival obeys Poisson distribution;

The service time of the picking table is constant, and the service time of the mobile system equipment follows the general distribution;

The capacity of the conveying buffer area is large enough;

A material box stores only one kind of commodity, and a kind of commodity is only stored in one material box.

(2) A performance parameter calculation module, which is used to calculate the throughput and order completion cycle corresponding to the corresponding open-loop queuing network model based on the open-loop queuing network model of the transshipment vehicle system and the open-loop queuing network model of the loop line system, respectively;

In the performance parameter calculation module, the throughput of the transfer vehicle system is the minimum value of the throughputs of the four types of equipment: the roadway vehicle, the transfer vehicle, the hoist and the picking table;

The order completion cycle of the reloading vehicle system is the sum of the service time and the waiting time of the service organization; among them, the service organization includes roadway vehicles, reloading vehicles, elevators and picking tables; the captain of the service organization is obtained by using the Polazek-Sinchin formula and waiting time.

In the performance parameter calculation module, the throughput of the loop system is the minimum value of the throughput of the roadway car, the hoist, the loop conveying line and the picking table;

The order completion cycle of the loop system is the sum of the service time and waiting time of the roadway car, hoist, loop conveyor and picking table.

(3) The evaluation module of the optimal multi-storey shuttle car system, which is used to evaluate the optimal multi-layer shuttle system according to the throughput and order completion cycle corresponding to the corresponding open-loop queuing network model under the condition that the number of layers and the number of lanes are certain. Multi-level shuttle system.

In this embodiment, the open-loop queuing network models of the two systems are first established, and then the system throughput and order completion period are calculated. Under the condition that the number of layers and the number of lanes are constant, the corresponding throughput and In the order completion cycle, the optimal multi-storey shuttle system is evaluated, which reduces the initial decision-making cost of the enterprise decision-making layer, reduces the input cost of manpower and material resources, and improves the accuracy of the multi-storey shuttle system evaluation.

Example 3

This embodiment provides a computer-readable storage medium on which a computer program is stored, and when the program is executed by a processor, implements the steps in the method for evaluating the performance of a multi-level shuttle system as shown in FIG. 1 .

In this embodiment, the open-loop queuing network models of the two systems are firstly established, and then the system throughput and order completion period are calculated. Under the condition that the number of layers and the number of lanes are constant, the corresponding throughput and In the order completion cycle, the optimal multi-storey shuttle system is evaluated, which reduces the initial decision-making cost of the enterprise decision-making layer, reduces the input cost of manpower and material resources, and improves the accuracy of the multi-storey shuttle system evaluation.

Example 4

This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and running on the processor, when the processor executes the program, the multi-level shuttle as shown in FIG. 1 is implemented. Steps in a System Performance Evaluation Method.

In this embodiment, the open-loop queuing network models of the two systems are first established, and then the system throughput and order completion period are calculated. Under the condition that the number of layers and the number of lanes are constant, the corresponding throughput and In the order completion cycle, the optimal multi-storey shuttle system is evaluated, which reduces the initial decision-making cost of the enterprise decision-making layer, reduces the input cost of manpower and material resources, and improves the accuracy of the multi-storey shuttle system evaluation.

As will be appreciated by one skilled in the art, embodiments of the present disclosure may be provided as a method, system, or computer program product. Accordingly, the present disclosure may take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present disclosure may take the form of a computer program product embodied on one or more computer-usable storage media having computer-usable program code embodied therein, including but not limited to disk storage, optical storage, and the like.

The present disclosure is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the disclosure. It will be understood that each process and/or block in the flowchart illustrations and/or block diagrams, and combinations of processes and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for implementing the functions specified in a flow or flow of a flowchart and/or a block or blocks of a block diagram.

These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory result in an article of manufacture comprising instruction means, the instructions The apparatus implements the functions specified in the flow or flow of the flowcharts and/or the block or blocks of the block diagrams.

These computer program instructions can also be loaded on a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that The instructions provide steps for implementing the functions specified in the flow or blocks of the flowcharts and/or the block or blocks of the block diagrams.

Those of ordinary skill in the art can understand that the realization of all or part of the processes in the methods of the above embodiments can be accomplished by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium. During execution, the processes of the embodiments of the above-mentioned methods may be included. The storage medium may be a magnetic disk, an optical disk, a read-only memory (Read-Only Memory, ROM), or a random access memory (Random Access Memory, RAM) or the like.

The above descriptions are only preferred embodiments of the present disclosure, and are not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure should be included within the protection scope of the present disclosure.

Claims (4)

1. A multi-layer shuttle system performance evaluation method is characterized by comprising the following steps:

respectively establishing an open-loop queuing network model of a transfer car system and an open-loop queuing network model of a loop system; the open-loop queuing network model of the transfer car system and the open-loop queuing network model of the loop system are both constructed under the following assumed conditions:

(1) when the material box returns to the warehouse, a random goods space distribution strategy is followed;

(2) stopping points of movable system equipment, namely a roadway vehicle, a transfer vehicle and a hoist, are finishing points of the last warehouse-in and warehouse-out operation;

(3) the order obeys a first-come first-serve principle;

(4) the order arrival obeys poisson distribution;

(5) the service time of the sorting table is constant, and the service time of the mobile system equipment follows general distribution;

(6) the capacity of the transmission buffer area is large enough;

(7) one bin is used for storing only one commodity, and one commodity is also stored in one bin;

respectively calculating the throughput and the order completion period corresponding to the corresponding open-loop queuing network model based on the open-loop queuing network model of the transfer car system and the open-loop queuing network model of the loop line system; the throughput of the transfer car system is the minimum value of the throughputs of the four devices, namely the laneway car, the transfer car, the elevator and the sorting table;

the order completion period of the transfer car system is the sum of the service time and the waiting time of the service mechanism; the service mechanism comprises a roadway vehicle, a transfer vehicle, a lifter and a sorting table; obtaining the captain and the waiting time of the service organization by utilizing a Pollacker-Sinkian formula;

the throughput of the loop system is the minimum value of the throughputs of the roadway vehicle, the elevator, the annular conveying line and the sorting table;

the order completion period of the loop system is the sum of the service time and the waiting time of the roadway vehicle, the elevator, the annular conveying line and the sorting table;

and under the condition that the number of layers and the number of roadways are fixed, evaluating the optimal multilayer shuttle system according to the throughput and the order completion period corresponding to the corresponding open-loop queuing network model.

2. A multi-layer shuttle system performance evaluation device is characterized by comprising:

the open-loop queuing network model establishing module is used for respectively establishing an open-loop queuing network model of the transfer car system and an open-loop queuing network model of the loop system; the switched vehicle system open-loop queuing network model and the loop line system open-loop queuing network model are both constructed under the following assumed conditions:

(1) when the material box returns to the warehouse, a random goods space allocation strategy is followed;

(2) stopping points of movable system equipment, namely a roadway vehicle, a transfer vehicle and a hoist, are finishing points of the last warehouse-in and warehouse-out operation;

(3) the order obeys a first come first serve principle;

(4) order arrival obeys poisson distribution;

(5) the service time of the sorting table is constant, and the service time of the mobile system equipment follows general distribution;

(6) the capacity of the transmission buffer area is large enough;

(7) one bin is used for storing only one commodity, and one commodity is also stored in one bin;

the performance parameter calculation module is used for respectively calculating the throughput and the order completion period corresponding to the corresponding open-loop queuing network model based on the switched vehicle system open-loop queuing network model and the loop line system open-loop queuing network model; the throughput of the transfer car system is the minimum value of the throughputs of the four devices, namely the laneway car, the transfer car, the elevator and the sorting table;

the order completion period of the transfer car system is the sum of the service time and the waiting time of the service mechanism; the service mechanism comprises a roadway vehicle, a transfer vehicle, a lifter and a sorting table; obtaining the captain and the waiting time of the service organization by utilizing a Pollacker-Sinkian formula;

the throughput of the loop system is the minimum value of the throughputs of the roadway vehicle, the elevator, the annular conveying line and the sorting table;

the order completion period of the loop system is the sum of the service time and the waiting time of the roadway vehicle, the elevator, the annular conveying line and the sorting table;

and the optimal multilayer shuttle system evaluation module is used for evaluating the optimal multilayer shuttle system according to the throughput and the order completion period corresponding to the corresponding open-loop queuing network model under the condition of certain layer number and roadway number.

3. A computer-readable storage medium on which a computer program is stored, the program, when executed by a processor, implementing the steps in the multi-layer shuttle system performance evaluation method according to claim 1.

4. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the steps of the method for evaluating the performance of a multi-layer shuttle system according to claim 1 when executing the program.

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