Comprehensive scheduling method for regular maintenance of flexible equipment

Abstract

The invention provides a comprehensive scheduling method for regular maintenance of flexible equipment. The method comprises the following steps of: firstly, adopting a strategy scheduling process of layer priority, short time and equipment priority; secondly, on the basis of a forest fire fighting model, according to the relation between the number of processed procedures and the number of unprocessed procedures and loss generated by the equipment in a maintenance period, the maintenance starting point and duration of the flexible equipment are determined; and finally, a dynamic adjustment strategy is adopted, so that maintenance of flexible equipment is realized, and the total time for product processing is reduced.

Description

Technical Field

[0001] This invention belongs to the field of computer integrated manufacturing technology, and in particular relates to a comprehensive scheduling method for the periodic maintenance of flexible equipment. Background Technology

[0002] Digitalization, networking, and intelligence in intelligent manufacturing are cutting-edge academic research topics worthy of study and summarization.

[0003] Flexible scheduling is an extension of traditional scheduling problems and is a class of problems that urgently need to be solved in actual production. Unlike traditional shop floor scheduling problems, flexible scheduling is a more complex NP-hard problem.

[0004] With the development of the times and the continuous improvement of people's living standards, the demand for personalized customized products with multiple varieties and small batches has surged. Therefore, traditional production and manufacturing processes, such as the scheduling methods of Flow-shop and Job-shop, can no longer meet the processing needs of diversified and complex products. In order to meet the production needs of such products, a comprehensive scheduling mode that represents the manufacturing constraint relationship between complex product workpieces in a tree structure and integrates "processing and assembly collaborative processing" has emerged.

[0005] Equipment management and maintenance are fundamental to modern enterprise production activities. Over long-term use, equipment experiences wear and tear, leading to reduced equipment health and consequently impacting production scheduling efficiency and costs. Equipment maintenance is the prerequisite and foundation for equipment use, and a crucial guarantee for its safe operation. Regular maintenance reduces equipment wear and tear, lowers failure rates, and improves equipment efficiency. Therefore, conducting reasonable and regular maintenance based on the equipment's health condition is an indispensable part of the enterprise's production process.

[0006] Among the numerous research findings on modern flexible integrated scheduling, there are no relevant results focusing on the periodic maintenance of flexible equipment. Therefore, it is necessary to develop periodic maintenance methods for flexible equipment. Summary of the Invention

[0007] This invention addresses the problem in existing flexible integrated scheduling methods for complex products with multiple varieties and small batches that fail to consider the need for regular equipment maintenance and neglect the wear and tear generated during processing, thus affecting equipment scheduling capabilities. It proposes a comprehensive scheduling method for regular equipment maintenance. Specifically, in the flexible scheduling of single-piece or small-batch tree-structured complex products where processing and assembly are performed simultaneously, this method optimizes both the complex product's structural attributes and the equipment's processing capacity, simultaneously reducing the total processing time for complex products, completing regular equipment maintenance, and improving the overall utilization rate of the equipment system.

[0008] This invention is achieved through the following technical solution: This invention proposes a comprehensive scheduling method for the periodic maintenance of flexible equipment, the method specifically being as follows:

[0009] Step 1: Establish the product processing technology tree and processing equipment sequence information;

[0010] Step 2: Determine the scheduling order and selected flexible processing equipment for all processes in the process tree according to the layer priority strategy, the short time strategy, and the equipment priority strategy;

[0011] Step 3: Utilize dynamic adjustment strategies to adjust the processing sequence and the selected flexible equipment;

[0012] Step 4: Calculate the number of processes completed, and based on the processing time, use the formula H... i =100% - 10%t i Calculate the current health status of each device;

[0013] Step 5: Determine if the number of processed steps has reached the total number of steps. If yes, proceed to Step 6; otherwise, proceed to Step 7.

[0014] Step 6: Equipment maintenance begins, maintenance duration WT = (1 - H) i )t i ;

[0015] Step 7: Determine if the set of schedulable operations is empty. If yes, proceed to Step 8; otherwise, remove the operation from the set of schedulable operations and proceed to Step 4.

[0016] Step 8: Output the product processing Gantt chart; scheduling ends.

[0017] The dynamic adjustment strategy is an optimization strategy based on the correspondence between processes and flexible equipment. It establishes a dynamic adjustment sequence of processes and selected flexible equipment using a forest fire fighting model. The specific dynamic adjustment strategy model based on the forest fire fighting model is as follows:

[0018] Assume the number of complex product processing steps is x, corresponding to the number of firefighters; let the total cost be C(x), and the total processing time for the complex product be T(x), corresponding to the firefighting loss cost; let the overall maintenance time of the equipment sequence be F(x), corresponding to the rescue cost; consider the maintenance time as the firefighting time t, where t1 represents the number of processing steps reaching the total number of complex product processing steps. At the moment when the equipment's processing capacity significantly decreases, maintenance is required. The maintenance duration is set as t2-t1 = the product of equipment wear and tear and time. The objective function formula for this model is:

[0019]

[0020] Furthermore, in flexible integrated scheduling, the same equipment has different processing capabilities for different processes. The start time and duration of maintenance are determined based on the processing quantity, processing time, and loss value of each process; the specific description is as follows:

[0021] (1) At the start of processing, all equipment is idle and in perfect working order;

[0022] (2) The necessary and sufficient condition for each process to begin processing is that its immediate preceding process has been completed.

[0023] (3) The equipment cannot perform any processing steps while it is being maintained;

[0024] (4) Both process processing and equipment maintenance are continuous processes and cannot be interrupted;

[0025] (5) Allow the equipment to be idle before maintenance begins.

[0026] Furthermore, based on the specific description, the mathematical model is established as follows:

[0027] Suppose a single complex product A has n processes, and the process sequence is A = {A} i}(1≤i≤n), the sequence of processing equipment on m flexible machines is M={M j}(1≤j≤m), Let i be the start time of the i-th process on the j-th equipment; Let i be the processing time of the i-th process on the j-th machine; Indicates process A i In device M j The time taken for the upper processing; t i H represents the processing time on the equipment within a specific maintenance cycle. i E represents the health status of the device at time t=i; i Indicates the end time of process i; The total maintenance time on the equipment is represented by:

[0028] Objective function:

[0029]

[0030] Constraints:

[0031]

[0032]

[0033] H i =100% - 10%t i (1≤i≤n) (4)

[0034] WT = (1-H) i )t i (1≤i≤n) (5)

[0035] Equation (1) represents the sum of the maximum completion time on all equipment and the equipment maintenance time, minimizing the sum; Equation (2) represents the predecessor-successor constraint relationship between processing steps, i.e., the start time of the former must be greater than the end time of the latter; Equation (3) represents the condition when the number of processed steps reaches the total number of steps. When the equipment begins maintenance; Equation (4) indicates that the equipment health value at time t=n is the initial health value minus the current loss value; Equation (5) indicates the time taken for the equipment to perform maintenance.

[0036] Furthermore, the equipment health value refers to the current working status of the equipment. The initial health value of the equipment before processing is set to 100%. The equipment health value decreases as the number of processed items increases.

[0037] Furthermore, the equipment priority strategy refers to using the sum of the number of processing steps of each piece of flexible equipment as the standard for whether an equipment is prioritized for processing. That is, the equipment with the most processing steps has the highest priority and has the advantage of prioritizing processing steps.

[0038] Furthermore, the dynamic adjustment strategy refers to: under the condition of meeting the constraints of the preceding process, comparing the total cost of completing the process on the corresponding flexible equipment, and selecting the smaller value, then adjusting the flexible processing equipment of the process.

[0039] Furthermore, the layer priority strategy means that for a tree-shaped product with an n-layer structure, the layers are defined from 1 to n from top to bottom starting from the root node. The higher the layer, the higher the layer priority, and the processes at the same layer have the same priority.

[0040] Furthermore, the short-time strategy means that in flexible integrated scheduling, processes can be processed on different equipment, each with a different processing time, and the equipment with the shortest processing time is selected first.

[0041] This invention proposes an electronic device, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps of a comprehensive scheduling method for the periodic maintenance of the flexible device.

[0042] This invention proposes a computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the steps of a comprehensive scheduling method for the periodic maintenance of the flexible device.

[0043] The beneficial effects of this invention are as follows:

[0044] To fill the research gap in the area of ​​periodic equipment maintenance in flexible integrated scheduling, this invention proposes an integrated scheduling method that considers the periodic maintenance of flexible equipment. The main contributions are:

[0045] (1) In flexible integrated scheduling, the problem of regular maintenance of flexible equipment was proposed and solved for the first time;

[0046] (2) In terms of process scheduling, the layer priority and short time strategy is adopted first to establish the initial process set; in terms of process adjustment, the flexible equipment priority strategy is adopted to dynamically adjust the process.

[0047] (3) In terms of optimization effect: Horizontally: Taking the hierarchical relationship and equipment priority in the tree-shaped product structure attributes as the research perspective, the parallel processing of processes is effectively improved; Vertically: Taking the dynamic adjustment of the flexible equipment selected for process processing as the research perspective, the maintenance start point and duration are determined, which effectively improves the compact processing of processes on the equipment and realizes regular maintenance activities on flexible equipment. Attached Figure Description

[0048] Figure 1 A time-dependent graph showing the processing capacity of the equipment;

[0049] Figure 2 The time relationship diagram of the optimized equipment processing capacity is provided for this invention.

[0050] Figure 3 This is a diagram illustrating the dynamic adjustment strategy;

[0051] Figure 4 A flowchart is designed for the comprehensive scheduling method for periodic maintenance of flexible equipment as described in this invention;

[0052] Figure 5 A schematic diagram of the manufacturing process tree for complex product A;

[0053] Figure 6 25 hours of unmaintained scheduling results Gantt chart;

[0054] Figure 7 The scheduling result of this invention is shown in Gantt chart 22, representing the man-hours. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] In flexible integrated scheduling, the same equipment has different processing capabilities for different processes. The start time and duration of maintenance are determined based on the processing quantity, processing time, and loss value of each process. A detailed description follows:

[0057] (1) At the start of processing, all equipment is idle and in perfect working order;

[0058] (2) The necessary and sufficient condition for each process to begin processing is that its immediate preceding process has been completed.

[0059] (3) The equipment cannot perform any processing steps while it is being maintained;

[0060] (4) Both process processing and equipment maintenance are continuous processes and cannot be interrupted;

[0061] (5) Allow the equipment to be idle before maintenance begins.

[0062] Based on the specific description, the mathematical model is established as follows:

[0063] Suppose a single complex product A has n processes, and the process sequence is A = {A} i}(1≤i≤n), the sequence of processing equipment on m flexible machines is M={M j}(1≤j≤m), Let i be the start time of the i-th process on the j-th equipment; Let i be the processing time of the i-th process on the j-th machine; Indicates process A i In device M j The time taken for the upper processing; t i H represents the processing time on the equipment within a specific maintenance cycle. i E represents the health status of the device at time t=i; i Indicates the end time of process i; The total maintenance time on the equipment is represented by:

[0064] Objective function:

[0065]

[0066] Constraints:

[0067]

[0068]

[0069] H i =100% - 10%t i (1≤i≤n) (4)

[0070] WT = (1-H)i )t i (1≤i≤n) (5)

[0071] Equation (1) represents the sum of the maximum completion time on all equipment and the equipment maintenance time, minimizing the sum; Equation (2) represents the predecessor-successor constraint relationship between processing steps, i.e., the start time of the former must be greater than the end time of the latter; Equation (3) represents the condition when the number of processed steps reaches the total number of steps. When the equipment begins maintenance; Equation (4) indicates that the equipment health value at time t=n is the initial health value minus the current loss value; Equation (5) indicates the time taken for the equipment to perform maintenance.

[0072] This invention includes a layer-priority strategy, a short-time strategy, a device-priority strategy, and a dynamic adjustment strategy. First, the classic integrated scheduling strategies, layer-priority and short-time strategies, are both optimization strategies focused on the processing steps themselves, improving the parallel processing capabilities of equipment. Second, the device-priority strategy prioritizes scheduling the processing steps corresponding to equipment with a large number of processing steps, optimizing the equipment itself to minimize idle time during processing. Finally, the dynamic adjustment strategy optimizes the relationship between processing steps and flexible equipment. Using a forest fire fighting model, it dynamically adjusts the processing sequence of steps and the selected flexible equipment sequence to improve equipment utilization and complete regular maintenance activities; this is the core strategy of this invention's algorithm.

[0073] Combination Figures 1-7 This invention proposes a comprehensive scheduling method for the periodic maintenance of flexible equipment, the method specifically comprising:

[0074] Step 1: Establish the product processing technology tree and processing equipment sequence information;

[0075] Step 2: Determine the scheduling order and selected flexible processing equipment for all processes in the process tree according to the layer priority strategy, the short time strategy, and the equipment priority strategy;

[0076] Step 3: Utilize dynamic adjustment strategies to adjust the processing sequence and the selected flexible equipment;

[0077] Step 4: Calculate the number of processes completed, and based on the processing time, use the formula H... i =100% - 10%t i Calculate the current health status of each device;

[0078] Step 5: Determine if the number of processed steps has reached the total number of steps. If yes, proceed to Step 6; otherwise, proceed to Step 7.

[0079] Step 6: Equipment maintenance begins, maintenance duration WT = (1 - H) i )t i ;

[0080] Step 7: Determine if the set of schedulable operations is empty. If yes, proceed to Step 8; otherwise, remove the operation from the set of schedulable operations and proceed to Step 4.

[0081] Step 8: Output the product processing Gantt chart; scheduling ends.

[0082] The dynamic adjustment strategy is an optimization strategy based on the correspondence between processes and flexible equipment. It establishes a dynamic adjustment sequence of processes and selected flexible equipment using a forest fire fighting model. The specific dynamic adjustment strategy model based on the forest fire fighting model is as follows:

[0083] Assume the number of complex product processing steps is x, corresponding to the number of firefighters; the total cost is C(x); the total processing time for the complex product is T(x), corresponding to the firefighting losses; the overall maintenance time of the equipment sequence is F(x), corresponding to the rescue costs; the equipment processing capacity is B(x), corresponding to the area of ​​forest burned; the maintenance time is considered as the firefighting time t, where t1 represents the number of processing steps reaching the total number of complex product processing steps. At this moment, the equipment's processing capacity significantly decreases, requiring maintenance. The maintenance duration is set as t2-t1 = the product of equipment wear and tear and time; t3 is the end time of product processing. The relationship between B(x) and t is shown in the diagram below. Figure 1 As shown, the time relationship diagram of the optimized equipment processing capacity of the present invention is as follows. Figure 2 As shown, the objective function formula for this model is:

[0084]

[0085] Will Defined as process A i In flexible equipment M j The total cost when the above processing is completed, such as Figure 3 As shown, using a dynamic adjustment strategy, when the ratio of the number of completed processing steps to the total number of steps reaches 2 / 3, the equipment begins maintenance. The total cost of each step when it is completed on the flexible equipment is calculated, and the corresponding processing equipment is allocated from the flexible equipment system to the steps to be scheduled so that the total cost is minimized.

[0086] In this invention, the time complexity of simplifying the process tree using the short-time strategy is O(n). When determining the process scheduling order and the selected processing equipment, the layer-first strategy needs to find the highest priority process, the short-time strategy needs to select the shortest processing time on the flexible equipment, and the equipment-first strategy needs to compare the number of processes that each equipment can process at each level, with time complexities of O(n), O(mn), and O(n²), respectively. Calculating equipment loss values ​​and health status requires calculations on n nodes, with a time complexity of O(n). Therefore, the time complexity of this invention is O(n²).

[0087] Relevant definitions and concepts

[0088] Loss coefficient: The total processing time for a complex product divided into ten equal parts without regular maintenance and dynamic adjustment is defined as 10% of the total processing time, both the initial value and the increment step.

[0089] Loss value: The product of the equipment's health value and the loss coefficient.

[0090] Maintenance cycle: The time interval between two consecutive maintenance activities.

[0091] Maintenance time: The product of equipment wear and tear and time. During the maintenance time, the equipment is unavailable.

[0092] Maintenance start point: The moment when the number of processing steps reaches the total number of processing steps of a complex product is defined as the equipment maintenance start time. From this moment, all equipment stops processing activities until the maintenance activities are completed.

[0093] Equipment health value refers to the current working status of the equipment. The initial health value of the equipment before processing is set to 100%. The equipment health value decreases as the number of processes increases.

[0094] The equipment priority strategy refers to using the sum of the number of processing steps of each piece of flexible equipment as the standard for whether an equipment is prioritized for processing. In other words, the equipment with the most processing steps has the highest priority and has the advantage of prioritizing processing steps.

[0095] The dynamic adjustment strategy refers to: under the condition of meeting the constraints of the preceding process, comparing the total cost of completing the process on the corresponding flexible equipment, and selecting the smaller value, then adjusting the flexible processing equipment of the process.

[0096] The layer priority strategy means that for a tree-shaped product with an n-layer structure, the layers are defined from 1 to n from top to bottom starting from the root node. The higher the layer, the higher the priority. Processes at the same layer have the same priority.

[0097] The short processing time strategy refers to the following: In flexible integrated scheduling, processes can be processed on different equipment, each with a different processing time. The equipment with the shortest processing time is selected first.

[0098] The method described in this invention first employs a "layer priority + short time + equipment priority" strategy to schedule processes; secondly, based on a forest fire fighting model, it determines the starting point and duration of flexible equipment maintenance according to the relationship between the number of processed processes and the number of unprocessed processes and the wear and tear on the equipment during the maintenance cycle; finally, it adopts a dynamic adjustment strategy, which not only achieves the maintenance of flexible equipment but also reduces the total processing time of the product.

[0099] Example

[0100] Suppose the manufacturing process diagram for a complex product A is as follows: Figure 5 As shown, there are 15 processing steps and 4 flexible devices. Each node includes three elements: the processing step, the corresponding flexible device, and the processing time on the corresponding flexible device. These three elements are separated by " / ". The arrows between the processes in the diagram indicate the constraint relationship between adjacent processes when they are closely connected. The starting point of the arrow indicates the preceding process, and the direction the arrow points to indicates the following process. Based on the total number of processing steps, it can be seen that equipment maintenance begins when the number of processing steps reaches 10.

[0101] Step 1: Utilize layer priority, shortest time, and device priority strategies to... Figure 5 The simplified scheduling sequence of the flexible process shown is as follows: the process with level 5 is A. 14 and A 15 The process that takes the least amount of time is Therefore, process A is scheduled first on equipment M1. 15 ; Comparing equipment priorities, equipment M1 requires 9 processing steps, M2 requires 11 processing steps, and M3 and M4 both require 10 processing steps. Therefore, the equipment priorities are: M1 = 9, M2 = 11, M3 = 10, M4 = 10. Since M2 has a higher priority than M4, process A is scheduled on equipment M2. 14 The scheduling sequence for the 5th level process is A. 15 / M1 / 2、A 14 / M2 / 6.

[0102] Step 2: Delete the scheduled process A 14 and A 15 The process at level 4 consists of 5 steps, namely A9, A... 10 A 11 A 12 and A 13 The process that takes the least amount of time is: The equipment priorities are: M1=8, M2=M3=M4=9. M3 and M4 have the same priority. Different equipment processes different operations, so they can be processed in parallel. Then, operation A is scheduled on equipment M2. 12 A10 and A 13 They have the same shortest processing time, but equipment M4 has a higher priority than M1, so the scheduling order of the operations at level 4 is {A}. 11 / M4 / 2, A9 / M3 / 2, A 12 / M2 / 3, A 13 / M3 / 4, A 10 / M1 / 4}.

[0103] Step 3: Following the layer-priority, shortest-time, and equipment-priority strategies in a loop, the process scheduling order for layers 3 and 2 is: {A6 / M3 / 2, A5 / M2 / 3, A8 / M3 / 4, A7 / M2 / 4} {A3 / M2 / 2, A4 / M4 / 3, A2 / M4 / 4}. The time taken for process A1 to be completed on equipment M1 is 25 man-hours, which is the total scheduling time for complex product A. The scheduling result Gantt chart is shown below. Figure 6 As shown.

[0104] Step 4: The total processing time is 25 man-hours. In this example, for every 2.5 man-hours of processing, the equipment wear value increases by 0.1, and the health status decreases by 10%. Considering equipment maintenance, the processes at the same level are dynamically adjusted in order of increasing total cost, as shown in Table 1. Process A 14 and A 15 With a level of 5, the number of processing steps x = 1 when calculating the total cost. Therefore, process A is scheduled first on equipment M1. 15 Secondly, based on equipment priority, process A is scheduled on equipment M2. 14 And so on, processing the 4th layer process A. 12 If the number of processed steps is 2, then the number of processed steps in this layer is x = 3. Therefore, process A 12 The process is adjusted to be processed on equipment M4, giving its subsequent processes {A7, A3} the advantage of being processed as early as possible. The scheduling order of the 4th and 5th layers is {A... 15 / M1 / 2、A 14 / M2 / 6},{A 11 / M4 / 2, A9 / M3 / 2, A 12 / M4 / 4, A 13 / M3 / 4, A 10 / M1 / 4}.

[0105] Table 1 Dynamically Adjusted Process Sequence Table

[0106]

[0107] Step 5: When scheduling the third-level process, the number of processing processes x = 8, and the minimum total cost of process A5 on the flexible equipment is... Therefore, process A5 is adjusted to be used on equipment M1. 15 and A 10 During intermediate processing, process A7 is scheduled on equipment M2 according to the total loss value, and processes A8 and A6 are scheduled on equipment M3. The scheduling order of this layer is {A5 / M1 / 4, A8 / M3 / 4, A7 / M2 / 4, A6 / M3 / 2}.

[0108] Step 6: The number of processing steps reaches 10, which means the total number of steps has been reached. The equipment begins maintenance at t=10. The equipment wear value, as shown in Table 2, reaches 0.4. Therefore, the equipment maintenance time is 0.4t. i =4, continue processing at t=14;

[0109] Step 7: In the process at level 2, A2 needs to be dynamically adjusted according to the calculated total cost. Therefore, process A2 is moved to equipment M1 for processing. The scheduling order at this level is {A3 / M2 / 2, A4 / M4 / 3, A2 / M1 / 4}. The total time for scheduling and maintaining complex product A using the algorithm of this invention is 22 man-hours. The Gantt chart of the scheduling results considering periodic maintenance is shown below. Figure 7 As shown.

[0110] Table 2 Equipment Processing Schedule

[0111]

[0112] To further illustrate the superiority of the present invention, the scheduling results considering dynamic adjustment and periodic maintenance are now compared with the scheduling results not considering dynamic adjustment and periodic maintenance.

[0113] The Gantt chart of product A's scheduling results, which does not consider the periodic maintenance of flexible equipment, is shown below. Figure 6 As shown, the total processing time is 25 man-hours. Figure 7 It can be seen that, under the original total scheduling time, by dynamically adjusting the process scheduling sequence, not only were regular maintenance activities implemented during the processing of equipment, reducing equipment wear, but the total product processing time was also shortened by 3 man-hours. As shown in Table 3, compared to Figure 6 Between t=0 and t=10, the utilization rates of flexible equipment M1, M3 and M4 all increased by 40%; considering regular maintenance, the overall utilization rates of flexible equipment also improved by 59%, 1%, 25% and 23% respectively.

[0114] Table 3 Equipment Utilization Rate

[0115]

[0116] In summary, compared with algorithms that do not consider periodic maintenance, this invention solves the periodic maintenance problem in flexible integrated scheduling systems for the first time, with the following main advantages:

[0117] (1) From the perspective of improving the optimization effect of process compact scheduling, this invention adopts the classic "layer priority" strategy and selects the equipment with the shortest processing time for each process for scheduling, effectively reducing the processing time of parallel processes; the proposed dynamic adjustment strategy further reduces the processing waiting time of processes, and effectively reduces the total processing time of complex products overall. For example, Figure 6 Processing step A5 begins at time t=2 on equipment M1, compared to... Figure 5 The process was completed 7 hours earlier, which also gave subsequent constraint processes A2 and A1 the advantage of earlier processing, with processing time reduced by 3 hours each.

[0118] (2) From the perspective of improving equipment utilization and optimization, this invention proposes for the first time a periodic maintenance strategy for flexible integrated scheduling of equipment sequences. While reducing the total processing time for complex products and improving the overall equipment utilization, it simultaneously completes equipment maintenance tasks. For example... Figure 6 As shown: ① All processes on equipment M1, M2, and M3 achieved seamless, high-density scheduling, with equipment utilization reaching 100% before the start of scheduled maintenance activities; ② The overall utilization rate of equipment M1 increased significantly from 32% to 91%. The flexible equipment sequence processed more processes in a short time, achieving the optimized effect of tightly integrated processing of processes on the equipment.

[0119] In the flexible integrated scheduling of complex products with multiple varieties and small batches, in order to address the impact of equipment wear and tear on production efficiency during the scheduling process, this invention proposes for the first time a research algorithm considering the periodic maintenance of flexible equipment. By dynamically adjusting the process scheduling sequence, it achieves periodic maintenance within the original planned total processing time and improves equipment utilization. Research results show that:

[0120] (1) The dynamic adjustment strategy proposed in this invention improves the overall utilization rate of flexible equipment by compactly scheduling processes. Compared with the algorithm that does not consider dynamic adjustment and periodic maintenance, the overall equipment utilization rate of this invention is increased by 59%, 1%, 25% and 23%, respectively;

[0121] (2) The present invention calculates wear and maintenance time together, which effectively improves the intensity of the process and reduces the total processing time of the product by 12% while completing the regular maintenance activities that account for 18% of the total processing time in the flexible equipment processing process.

[0122] (3) This invention comprehensively utilizes the strategy of “layer priority + short time + equipment priority + dynamic adjustment” to achieve scheduling optimization of complex products in both vertical and horizontal directions, and realizes regular maintenance in flexible integrated scheduling.

[0123] This invention provides a novel method for solving the comprehensive scheduling problem of complex products, expanding the approach to problem-solving and possessing certain theoretical and practical significance. Furthermore, this invention lays the foundation for subsequent fixed-cycle equipment maintenance, allowing research to be further extended to the design and implementation of periodic maintenance in complex distributed manufacturing scheduling systems with collaborative computing capabilities.

[0124] This invention proposes an electronic device, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps of a comprehensive scheduling method for the periodic maintenance of the flexible device.

[0125] This invention proposes a computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the steps of a comprehensive scheduling method for the periodic maintenance of the flexible device.

[0126] The memory in this application embodiment can be volatile memory or non-volatile memory, or it can include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DRRAM). It should be noted that the memory used in the methods described in this invention is intended to include, but is not limited to, these and any other suitable types of memory.

[0127] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., high-density digital video discs (DVDs)), or semiconductor media (e.g., solid-state disks (SSDs)).

[0128] In implementation, each step of the above method can be completed by integrated logic circuits in the processor's hardware or by instructions in software. The steps of the method disclosed in the embodiments of this application can be directly implemented by a hardware processor, or by a combination of hardware and software modules in the processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, detailed descriptions are omitted here.

[0129] It should be noted that the processor in the embodiments of this application can be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method embodiments can be completed by the integrated logic circuitry in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied as being executed by a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory, and the processor reads the information in the memory and, in conjunction with its hardware, completes the steps of the above methods.

[0130] The above provides a detailed description of the comprehensive scheduling method for regular maintenance of flexible equipment proposed in this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A comprehensive scheduling method for the periodic maintenance of flexible equipment, characterized in that, The method is specifically as follows: Step 1: Establish the product processing technology tree and processing equipment sequence information; Step 2: Determine the scheduling order and selected flexible processing equipment for all processes in the process tree according to the layer priority strategy, the short time strategy, and the equipment priority strategy; Step 3: Utilize dynamic adjustment strategies to adjust the processing sequence and the selected flexible equipment; Step 4: Calculate the number of processes completed, and based on the processing time, use the formula H... i =100% - 10%t i Calculate the current health status of each device; Step 5: Determine if the number of processed steps has reached the total number of steps. If yes, proceed to Step 6; otherwise, proceed to Step 7. Step 6: Equipment maintenance begins, maintenance duration WT = (1 - H) i )t i ; Step 7: Determine if the set of schedulable operations is empty. If yes, proceed to Step 8; otherwise, remove the operation from the set of schedulable operations and proceed to Step 4. Step 8: Output the product processing Gantt chart; scheduling ends. The dynamic adjustment strategy is an optimization strategy based on the correspondence between processes and flexible equipment. It establishes a dynamic adjustment sequence of processes and selected flexible equipment using a forest fire fighting model. The specific dynamic adjustment strategy model based on the forest fire fighting model is as follows: Assume the number of processes for a complex product is x, corresponding to the number of firefighters; let the total cost be C(x), and the total processing time for the complex product be T(x), corresponding to the firefighting loss cost; let the overall maintenance time of the equipment sequence be F(x), corresponding to the rescue cost; consider the maintenance time as the firefighting time t, where t1 represents the number of processing processes reaching the total number of processes for the complex product. At the moment when the equipment's processing capacity significantly decreases, maintenance is required. The maintenance duration is set as t2-t1 = the product of equipment wear and tear and time. The objective function formula for this model is:

2. The method according to claim 1, characterized in that, In flexible integrated scheduling, the same equipment has different processing capabilities for different processes. The start time and duration of maintenance are determined based on the processing quantity, processing time, and loss value of each process. A detailed description follows: (1) At the start of processing, all equipment is idle and in perfect working order; (2) The necessary and sufficient condition for each process to begin processing is that its immediate preceding process has been completed. (3) The equipment cannot perform any processing steps while it is undergoing maintenance; (4) Both process processing and equipment maintenance are continuous processes and cannot be interrupted; (5) Allow the equipment to be idle before maintenance begins.

3. The method according to claim 2, characterized in that, Based on the specific description, the mathematical model is established as follows: Suppose a single complex product A has n processes, and the process sequence is A = {A} i }(1≤i≤n), the sequence of processing equipment on m flexible machines is M={M j }(1≤j≤m), Let i be the start time of the i-th process on the j-th equipment; Let i be the processing time of the i-th process on the j-th machine; Indicates process A i In device M j The time taken for the upper processing; t i H represents the processing time on the equipment within a specific maintenance cycle. i E represents the health status of the device at time t=i; i Indicates the end time of process i; The total maintenance time on the equipment is represented by: Objective function: Constraints: H i =100%-10%t i ,(1≤i≤n) (4) WT=(1-H i )t i ,(1≤i≤n) (5) Equation (1) represents the sum of the maximum completion time on all equipment and the equipment maintenance time, minimizing the sum; Equation (2) represents the predecessor-successor constraint relationship between processing steps, i.e., the start time of the former must be greater than the end time of the latter; Equation (3) represents the condition when the number of processed steps reaches the total number of steps. When the equipment begins maintenance; Equation (4) indicates that the equipment health value at time t=n is the initial health value minus the current loss value; Equation (5) indicates the time taken for the equipment to perform maintenance.

4. The method according to claim 3, characterized in that, Equipment health value refers to the current working status of the equipment. The initial health value of the equipment before processing is set to 100%. The equipment health value decreases as the number of processes increases.

5. The method according to claim 3, characterized in that, The equipment priority strategy refers to using the sum of the number of processing steps of each piece of flexible equipment as the standard for whether an equipment is prioritized for processing. In other words, the equipment with the most processing steps has the highest priority and has the advantage of prioritizing processing steps.

6. The method according to claim 3, characterized in that, The dynamic adjustment strategy refers to: under the condition of meeting the constraints of the preceding process, comparing the total cost of completing the process on the corresponding flexible equipment, and selecting the smaller value, then adjusting the flexible processing equipment of the process.

7. The method according to claim 3, characterized in that, The layer priority strategy means that for a tree-shaped product with an n-layer structure, the layers are defined from 1 to n from top to bottom starting from the root node. The higher the layer, the higher the priority. Processes at the same layer have the same priority.

8. The method according to claim 3, characterized in that, The short processing time strategy refers to the following: In flexible integrated scheduling, processes can be processed on different equipment, each with a different processing time. The equipment with the shortest processing time is selected first.

9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1-8.

10. A computer-readable storage medium for storing computer instructions, characterized in that, When the computer instructions are executed by the processor, they implement the steps of the method according to any one of claims 1-8.

Images