A rapid evaluation method for flow-shop group scheduling

Abstract

The application discloses a flow shop group scheduling fast evaluation method, relates to the technical field of workshop scheduling, and constructs a fast evaluation method between groups and in groups based on an insertion neighborhood; the method comprises the following steps: step 1, calculating the forward completion time of workpieces in a group on a machine; step 2, calculating the backward completion time of the workpieces in the group on the machine; step 3, obtaining the maximum completion time; step 4, updating the forward completion time; and step 5, updating the backward completion time. The application solves the problem of quickly evaluating the maximum completion time as a target value in the flow shop group scheduling problem, reduces the calculation time, can effectively avoid repeated evaluation, saves the calculation cost, and improves the scheduling efficiency.

Description

Technical Field

[0001] This invention relates to the field of workshop scheduling technology, and in particular to a rapid evaluation method for group scheduling in assembly line workshops. Background Technology

[0002] With economic development, manufacturing has become a crucial pillar of the national economy. The development and application of cell manufacturing and group technologies have a significant impact on efficient batch manufacturing systems. In cell manufacturing systems, resources are divided into smaller organizational units called manufacturing cells. A manufacturing cell typically consists of a series of specialized machines, while a group comprises workpieces with similar requirements in terms of tooling, setup, and operational sequence. Group scheduling has proven relevant to various fields of cell manufacturing development, reflected in a wide range of practical applications, such as automotive painting, furniture production, the semiconductor industry, metal parts punching, centrifugal pump manufacturing, printed circuit boards, and general electronics manufacturing. Cell manufacturing simplifies scheduling processes, shortens production time, and improves the reliability of production systems, which is particularly beneficial for highly automated systems. It is becoming one of the most important manufacturing models in modern enterprises, such as Huawei Technologies Co., Ltd., Foxconn Technology Group, and the automotive assembly industry.

[0003] In existing research on the group scheduling problem in flow shops, neighborhood search based on insertion is generally considered a method to obtain high-quality scheduling sequences. However, solving for the objective value after performing the insertion operation leads to a large amount of computation, consuming a significant amount of optimization scheduling time. This prevents the full utilization of optimization scheduling methods, resulting in unreasonable scheduling sequences, potentially causing idle production lines, increased production time, and reduced production efficiency. It may also lead to insufficient or wasted resources, increasing production costs. Furthermore, it may cause a decrease in the processing accuracy of certain processes, affecting product quality. However, few studies have considered designing corresponding fast evaluation methods to reduce the time complexity of solving for the objective value. Therefore, this is a problem of significant practical importance that urgently needs to be solved. Summary of the Invention

[0004] To better address the issue of rapid calculation of target values ​​in distributed flow shop group scheduling problems with startup time, an effective rapid evaluation method is proposed, namely, a rapid evaluation method for flow shop group scheduling. Based on the characteristics of group problems, the rapid evaluation method based on insertion neighborhood is divided into inter-group insertion acceleration criteria and intra-group insertion acceleration criteria.

[0005] This invention provides a rapid evaluation method for group scheduling in a production line workshop, comprising the following steps:

[0006] Step 1: Calculate the group workpiece In the machine Forward completion time Step 2: Calculate the group workpiece In the machine Backward completion time Step 3: Obtain the maximum completion time;

[0007] Step 4: Update forward completion time ;

[0008] Step 5: Update backward completion time ;

[0009] in, , , .

[0010] Furthermore, based on the characteristics of grouped problems, fast evaluation methods based on insertion neighborhoods are divided into inter-group insertion acceleration criteria and intra-group insertion acceleration criteria.

[0011] Furthermore, based on the characteristics of grouped problems, fast evaluation methods based on insertion neighborhoods are divided into inter-group insertion acceleration criteria and intra-group insertion acceleration criteria.

[0012] Furthermore, the inter-group insertion acceleration criterion includes:

[0013] Assuming manufacturing unit Include Groups, try to Each group is inserted into the manufacturing unit. In order to minimize the maximum completion time;

[0014] Specifically, let variable t=1, and consider grouping... insert;

[0015] Calculation group workpiece In the machine Forward completion time ;

[0016] Calculation group workpiece In the machine Backward completion time ;

[0017] hypothesis group Insert into Location, Calculate the forward completion time after insertion. ;

[0018] Calculate the insertion group based on the forward completion time and the backward completion time. Maximum completion time ;

[0019] renew Forward completion time of location and subsequent locations ,renew Backward completion time of the location and previous locations ;

[0020] make , ;

[0021] Repeat steps 3-5 and "Let , "Until all" Insert a group.

[0022] Furthermore, in the calculation group workpiece In the machine Forward completion time The calculation formula is as follows:

[0023] ;

[0024] ;

[0025] ;

[0026] ;

[0027] in, Representation group and group In the machine Preparation time Representation group workpiece In the machine The processing time.

[0028] Furthermore, in the calculation group workpiece In the machine Backward completion time The calculation formula is as follows:

[0029]

[0030]

[0031] ;

[0032] ;

[0033] in, Representation group The number of workpieces in the process, >0.

[0034] Furthermore, the forward completion time after the calculation insertion... The calculation formula is as follows:

[0035] ;

[0036]

[0037] ;

[0038] .

[0039] Furthermore, regarding the maximum completion time The calculation formula is as follows:

[0040]

[0041] Furthermore, the intra-group insertion acceleration criterion includes:

[0042] hypothesis group middle, One workpiece has been scheduled, among which The total number of workpieces in the group. >0; Attempt to move the workpiece Insert into group This minimizes the maximum completion time, where t > 0;

[0043] Specifically,

[0044] Calculation group workpiece Forward completion time on machine i ;

[0045] Calculation group Workpiece j in the machine Backward completion time ;

[0046] Assuming the workpiece Insert into Location, Calculate the forward completion time after insertion. ;

[0047] Calculate the group based on the forward completion time and backward completion time. Insert workpiece Maximum completion time ;

[0048] renew Forward completion time of location and subsequent locations ,renew Backward completion time of the location and previous locations .

[0049] Furthermore, the forward completion time after the calculation insertion... The calculation formula is as follows:

[0050] ;

[0051]

[0052] Furthermore, regarding the maximum completion time The calculation formula is as follows:

[0053]

[0054] The rapid evaluation method for group scheduling in a production line provided by this invention has the following technical effects:

[0055] Methodological aspects:

[0056] (1) This invention uncovers the hidden problem characteristics, analyzes the relationship between workpieces in and between groups during the insertion process, and divides the fast evaluation method based on the insertion neighborhood into inter-group insertion acceleration criteria and intra-group insertion acceleration criteria according to the characteristics of grouped problems.

[0057] (2) By using the inter-group acceleration criterion, the time complexity is reduced from Reduce to ;

[0058] (3) By using the intra-group acceleration criterion, the time complexity is reduced from Reduce to ;

[0059] (4) By recording the forward completion time and backward completion time at any time, the target value can be quickly obtained based on the forward completion time and backward completion time when the maximum completion time needs to be calculated.

[0060] Application level:

[0061] (1) Compared with traditional calculation methods, the method provided by this invention reduces the time complexity of calculation, greatly shortens the calculation time, and improves the calculation efficiency;

[0062] (2) The scheduling scheme can be iteratively optimized multiple times within the same optimization time, fully exploring the potential of the optimization scheduling method to obtain a more accurate scheduling scheme and avoid errors in the scheduling process;

[0063] (3) It can efficiently schedule and optimize workshop tasks according to production needs, helping enterprises improve production efficiency;

[0064] (4) The optimized scheduling scheme can reduce the idle time of materials and equipment, improve the stability and reliability of the production line, reduce resource waste, and thus reduce production costs.

[0065] Therefore, this invention provides a rapid evaluation method for group scheduling in flow workshops. Based on the insertion of neighborhoods, this method, taking a distributed flow workshop with startup time as an example, improves the calculation methods between and within groups, reduces the time for calculating or evaluating target values, and improves the efficiency of workshop scheduling. Furthermore, this invention effectively solves the target value calculation process in group problems, providing a good solution for rapidly calculating target values ​​in group scheduling of flow workshops. Attached Figure Description

[0066] Figure 1 A comparison chart of confidence intervals for this invention. Detailed Implementation

[0067] Embodiments of the invention will now be described more fully below with reference to the accompanying drawings, which illustrate examples of the invention. However, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Throughout the text, the same numerals denote the same elements.

[0068] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It will be further understood that, unless expressly defined herein, the terms used herein shall be interpreted as having the meaning consistent with their meaning in the context of this specification and the relevant field, and shall not be interpreted in an idealized or overly formal sense.

[0069] The invention is described below with reference to flowchart illustrations and / or block diagrams of methods, systems, and computer program products according to embodiments of the invention. It will be understood that some blocks of the flowchart illustrations and / or block diagrams, as well as combinations of some blocks of the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be stored or implemented in microcontrollers, microprocessors, digital signal processors (DSPs), field-programmable gate arrays (FPGAs), state machines, programmable logic controllers (PLCs) or other processing circuits, general-purpose computers, or special-purpose computers. The instructions are used in computers or other programmable data processing devices (e.g., production machines) to create means or block diagram blocks for implementing the functions / actions specified in the flowcharts and / or block diagrams, which are executed by the processor of the computer or other programmable data processing device.

[0070] These computer program instructions may also be stored in a computer-readable storage medium that can instruct a computer or other programmable data processing device to operate in a particular manner, thereby causing the instructions stored in the computer-readable storage medium to produce an article of art including instruction means. This implements the functions / actions specified in the flowcharts and / or block diagrams.

[0071] Computer program instructions can also be loaded onto 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, thereby making the instructions executable on the computer or other programmable apparatus possible. Other programmable devices provide steps for implementing the functions / actions specified in the flowcharts and / or block diagrams. It should be understood that the functions / actions indicated in the blocks may not occur in the order shown in the operation diagram. For example, depending on the functions / actions involved, two consecutively shown blocks may actually be performed substantially simultaneously, or sometimes they may be performed in reverse order. Although some diagrams include arrows on the communication path to indicate the main direction of communication, it should be understood that communication may occur in the direction opposite to the depicted arrows.

[0072] The specific implementation process of this invention is as follows:

[0073] Taking printed circuit boards (PCBs) as an example, PCBs are a crucial component of electronic products. During PCB manufacturing, different types of PCB components need to be scheduled. First, the PCB components are grouped according to their type, for example, into a first PCB group and a second PCB group. The number of chips loaded onto the machine is also different for processing these two different PCB groups. Specifically, the number of chips loaded onto the machine remains constant when processing the first PCB group. When the first PCB group is finished and it's time to switch to processing the second PCB group, the machine must first be cleaned and maintained to meet the conditions required for processing the second PCB group. Therefore, the switching time depends on the order of the PCB groups, and the switching time required between different PCB groups is also different. In this case, the scheduling problem is a flow shop group scheduling problem with sequence-dependent setup times.

[0074] Therefore, this invention provides a rapid evaluation method for group scheduling in a production line workshop, comprising the following steps:

[0075] Step 1: Calculate the forward completion time of workpiece j in group l on machine i. Step 2: Calculate the backward completion time of workpiece j in group l on machine i. Step 3: Obtain the maximum completion time;

[0076] Step 4: Update forward completion time ;

[0077] Step 5: Update backward completion time ;

[0078] in, , , .

[0079] Specifically, taking a distributed workflow workshop with startup time as an example, the main implementation process includes the following:

[0080] Based on the characteristics of grouped problems, fast evaluation methods based on insertion neighborhood are divided into inter-group insertion acceleration criteria and intra-group insertion acceleration criteria.

[0081] In some embodiments of this application, the inter-group insertion acceleration criteria include:

[0082] Assuming a PCB manufacturing unit Include Groups, try to Each group is inserted into the PCB manufacturing unit. In this way, the maximum completion time is minimized; among them, , ;

[0083] Specifically, let variables be defined. Consider group insert;

[0084] Calculation group workpiece In the machine Forward completion time ,in, Representation group and group In the machine Preparation time Representation group workpiece In the machine The processing time is calculated using the following formula:

[0085] ;

[0086]

[0087] ;

[0088] ;

[0089] in, It is an integer;

[0090] Calculation group workpiece In the machine Backward completion time ,in, Representation group The number of workpieces in the process, >0, the calculation formula is as follows:

[0091]

[0092]

[0093] ;

[0094] ;

[0095] hypothesis group Insert into Location, Calculate the forward completion time after insertion. ;

[0096] ;

[0097]

[0098] ;

[0099] ;in, It is an integer;

[0100] Calculate the insertion group based on the forward completion time and the backward completion time. Maximum completion time ;

[0101]

[0102] renew Forward completion time of location and subsequent locations ,renew Backward completion time of the location and previous locations ;

[0103] make , ;

[0104] Repeat steps 3-5 and " , "Until all" Insert a group.

[0105] Some embodiments of this application reduce time complexity from [previous level] by using an inter-group acceleration criterion. Reduce to .

[0106] In some embodiments of this application, the intra-group insertion acceleration criteria include:

[0107] hypothesis group middle, One workpiece has been scheduled, among which For group The total number of all workpieces in the process. >0; Attempt to move the workpiece Insert into group This minimizes the maximum completion time, where ;

[0108] Specifically,

[0109] Calculation group workpiece In the machine Forward completion time ;

[0110] Calculation group workpiece In the machine Backward completion time ;

[0111] Assuming the workpiece Insert into Location, Calculate the forward completion time after insertion. The calculation formula is as follows:

[0112] ;

[0113]

[0114] in, It is an integer;

[0115] Calculate the group based on the forward completion time and backward completion time. Insert workpiece Maximum completion time The calculation formula is as follows:

[0116]

[0117] renew Forward completion time of location and subsequent locations ,renew Backward completion time of the location and previous locations .

[0118] Some embodiments of this application reduce time complexity from [previous level] by using an intra-group acceleration criterion. Reduce to .

[0119] By recording forward and backward completion times in real time, the target value can be obtained based on the forward and backward completion times when the maximum completion time needs to be calculated, thereby reducing calculation time and improving the efficiency of workshop scheduling.

[0120] Figure 1 This is a confidence interval comparison chart of the present invention, wherein tIGA applies the proposed fast evaluation method. The proposed rapid evaluation method was not applied; RPI, representing relative percentage increase, was used as a performance metric, and the formula for calculating RPI is as follows: ,in, This represents the maximum completion time obtained by a specific algorithm when solving a specific computational example, while This indicates the minimum maximum completion time among all algorithms used to solve the same problem; specifically, from Figure 1 As can be seen from the RPI values, the RPI results of tIGA are significantly better than those of other methods. This demonstrates that the method of the present invention accelerates the calculation time of the target value, fully utilizes the algorithm's performance, and can converge to the best value at a faster convergence speed.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Any modifications or changes made to the present invention by those skilled in the art after reading this application and referring to the above embodiments are within the scope of protection claimed in the pending claims of this application.

Claims

1. A rapid evaluation method for group scheduling in a production line workshop, characterized in that, Includes the following steps: Assume manufacturing unit k contains Each group will A set of groups is inserted into manufacturing unit k such that the maximum completion time is minimized; where k >

0. >0; Let variable t=1, consider group Insertion; the rapid evaluation method uses the between-group insertion acceleration criterion; The inter-group insertion acceleration criteria include: Step 1: Calculate the forward completion time of workpiece j in group l on machine i. ; The calculation method is as follows: ； ； ； in, This indicates the preparation time for group l-1 and group l on machine i. This indicates the processing time of workpiece j in group l on machine i; Step 2: Calculate the backward completion time of workpiece j in group l on machine i. ; The calculation method is as follows: ； ； in, This indicates the number of workpieces in group l. >0; Step 3: Obtain the maximum completion time; Specifically, hypothesis group Insert at position q. Calculate after insertion Forward completion time ; The calculation method is as follows: ； ； ； Calculate the insertion group based on the forward completion time and the backward completion time. Maximum completion time ; The calculation method is as follows: ； Step 4: Update forward completion time ; Specifically, update the forward completion time of position q and subsequent positions. , Step 5: Update backward completion time ; Specifically, update the backward completion time of position q and its previous positions. ; Let t = t + 1, ; Repeat steps 3-5 and the above-mentioned setting t=t+1. until all Insert a group.

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