Method for cooperatively executing work order by multiple crown blocks based on work order conversion

Abstract

The invention discloses a work order conversion-based method for cooperatively executing a work order by multiple crown blocks, which comprises the following steps of: if two crown blocks have hidden dangers of intersection and operation conflict on operation paths for executing respective work orders, exchanging partial tasks of two work orders to avoid intersection conflict (collision); the step of exchanging the partial tasks of the two work orders refers to the step of exchanging task termination points of the two work orders or the step of exchanging task starting points of the two work orders; after the work orders are exchanged, generating a new work order; and the two crown blocks continue to execute the work order task according to the new work order. According to the method, crown block collision can be effectively avoided, and the working efficiency is improved.

Description

Technical Field

[0001] The present invention relates to a method for multiple overhead cranes to collaboratively execute work orders based on work order conversion. Specifically, it relates to an automated scheduling technology with a program as the core, belonging to the field of automation. Background Art

[0002] The operation strategy of the automated overhead crane relies on the guidance of the program, and the strategy of the program will directly affect the efficiency of the overhead crane during operation. And during the operation, safety issues must be fully considered to ensure safe operation. The existing technology includes many different forms. The most commonly used algorithm is usually to allow the overhead crane with a higher priority to enter the public area, and the overhead crane with a lower priority waits outside the public area for the overhead crane with a higher priority to complete the work and withdraw from the public area. However, this scheme has certain disadvantages. Disadvantage 1. In the process of executing this scheme, the work order being executed by the overhead crane with a lower priority needs to be suspended, so it is assumed that the control system must have the function of suspending the execution of the work order. If a system does not have this function, this strategy cannot be used, so the adaptability of this strategy is lacking. Disadvantage 2. The generation of work orders is usually uncertain (the uncertainty here refers to the difficulty in predicting the starting and end points of the next work order, etc.), so the work order with a low priority also faces an uncertain waiting time, which may seriously damage the operating efficiency of the system. The third disadvantage is that under certain working conditions, the efficiency of multiple overhead cranes working together is not as good as that of a single overhead crane, or if there is a loophole in the execution logic design, it will cause a deadlock (two overhead cranes are waiting for the other to finish working).

[0003] When multiple overhead cranes are performing work tasks on one track at the same time, it is possible that the operating areas of the overhead cranes may intersect at the same time. However, the track can only serve one of them at the same time, so one of the overhead cranes needs to wait for the other one to operate. If not handled properly, the operating efficiency will be greatly reduced.

[0004] Therefore, it is necessary to design a method for multiple overhead cranes to collaboratively execute work orders. Summary of the invention

[0005] The present invention is used for allocating and adjusting work orders during the operation of an automated overhead crane, thereby improving the operation efficiency of the overhead crane.

[0006] The technical solution of the invention is as follows:

[0007] A method for multiple overhead cranes to collaboratively execute work orders based on work order conversion. If two overhead cranes have a hidden danger of crossing and conflicting in the running paths of executing their respective work orders, part of the tasks of the two work orders are exchanged to avoid crossing conflicts (collisions).

[0008] Exchanging partial tasks of two work orders means exchanging the task end points of the two work orders, or exchanging the task start points of the two work orders;

[0009] After the work orders are exchanged, a new work order is generated;

[0010] The two overhead cranes continue to execute work order tasks according to the new work order.

[0011] If at least one of the starting work points of the two work orders appears before the intersection of the work order execution paths, the work order update is completed through one conversion (swapping the end points of the two work orders);

[0012] If both starting points are after the intersection point, the starting and ending points of the two work orders are swapped at the same time to complete the work order update.

[0013] If the conversion cannot be completed directly by exchanging the starting or ending work points of the work order, suspend one of the work orders to complete the task.

[0014] The suspension means that the previously executed path is directly regarded as a completed work order, and a to-do work order is newly generated for the uncompleted part.

[0015] Beneficial effects:

[0016] 1. The method of decomposing work orders can be used to replace the function of pausing work orders, so this method has a wider range of applications (even on overhead cranes that do not have the pause function, it can simulate the same ability as the pause function. That is, the previously executed path is directly regarded as a completed work order, and a to-do work order is regenerated for the unfinished part. That is, the end of the work order replaces the suspension of the work order, and at the same time, the same effect as the previous suspension can be achieved.

[0017] 2. Using this method of decomposing work orders will not increase the time it takes to execute the work orders. The traditional method of doing overhead crane avoidance will sacrifice execution time.

[0018] 3. Propose a mathematical model transformation problem: The problem of how to execute work orders on two overhead cranes at the same time is transformed into the problem of how to make the execution path of the work order after equivalent transformation not produce intersection points in the Cartesian coordinate system.

[0019] 4. A work order classification method is proposed to extract the features of work orders and classify them. This classification is used to further strengthen the mathematical modeling of the work order conversion problem.

[0020] The present invention can effectively improve the operating efficiency of the overhead crane and avoid collision accidents caused by the overhead crane during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the L overhead travelling car and the R overhead travelling car on the same track at the same time;

[0022] Figure 2 is the curve of the x position of the two overhead cranes changing with time t;

[0023] Figure 3 (a) is a schematic diagram of the changes in the work order operation lines of the two overhead cranes;

[0024] Figure 3 (b) is a schematic diagram of the actual operation process of the two overhead cranes;

[0025] Figure 4 The schematic diagram of the location of the overhead crane (where Figure 4 (a) is a schematic diagram of the current position of the overhead crane when the starting position A is smaller than the ending position B; Figure 4 (b)-(d) are schematic diagrams corresponding to the position of the overhead crane being less than A, between A and B, and greater than B, respectively);

[0026] Figure 5 The schematic diagram of the location of the overhead crane (where Figure 5 (a) is a schematic diagram of the current position of the overhead crane when the starting position A is greater than the ending position B; Figure 5 (b)-(d) are schematic diagrams corresponding to the position of the overhead crane being less than B, between A and B, and greater than A, respectively);

[0027] Figure 6 Schematic diagram of the execution routes of four types of work orders ( Figure 6 (a)-(d) correspond to Class A1, A2, B1 and B2 lines respectively);

[0028] Figure 7 Schematic diagram of seven ways to avoid collision: ( Figure 7 (a)-(g) are schematic diagrams corresponding to the situations of A1A1, B1A1, B1B1, A2A1, B1B2, B2A1, and B1A2 respectively);

[0029] Figure 8 There are four situations where the work order execution routes intersect in the coordinate system ( Figure 8 (a)-(d) are schematic diagrams corresponding to the situations of A1B2, A2B1, B2A2, and A2B2 respectively);

[0030] Fig. 9 There are four situations after the work order is modified ( Fig. 9 (a)-(d) are schematic diagrams corresponding to the situations of A1B2, A2B1, B2A2, and A2B2 respectively);

[0031] Fig.10 This is a schematic diagram of the work order combination ( Fig.10(a) At least one of the starting work points of the two work orders appears before the intersection of the work order execution paths, Fig.10 (b) The case where both starting points appear after the intersection point);

[0032] Fig.11 This is a schematic diagram of the execution of work orders ( Fig.11 (a) is the case where at least one of the starting work points of the two work orders appears before the intersection of the work order execution paths, Fig.11 (b) is the case where both starting points are after the intersection point.)

[0033] Fig.12 This is a schematic diagram of work order decomposition; Fig.12 (a)-(d) are the decomposition of A1, A2, B1 and B2 type work orders.)

[0034] Fig.13 For the conversion view of the work order ( Fig.13 (a)-(d) are the conversion cases of A1A2, B1B2, A2A2, and B2 B2 work orders). DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0036] Mathematical modeling:

[0037] In order to ensure the reliability of modeling, some prerequisites need to be provided for the overhead crane system: Condition 1, the running speed of different overhead cranes on the track is the same; Condition 2, all the following descriptions of the position of the overhead crane are its right boundary for the left overhead crane and its left boundary for the right overhead crane, that is: even if the two overhead cranes collide, it is the right side of the left overhead crane that collides with the left side of the right overhead crane, so the right boundary position of the left overhead crane is selected to represent its entirety, and the left boundary position of the right overhead crane is selected to represent its entirety. This processing makes the modeling process more convenient; Condition 3, the work of different overhead cranes at the same position is equivalent.

[0038] When the crane executes a work order, it will first go to the starting point (note that the starting point here is not the position of the crane when it receives the work order, but the starting position of the current work order. This position is not necessarily the same as the position of the crane when it receives the work order, so the crane needs to move to this position first), and then move from the starting point to the end point. There can be multiple cranes on a track at the same time, such as Figure 1 As shown, both the L overhead travelling car and the R overhead travelling car are on the same track at the same time.

[0039] according to Figure 1 It can be seen that due to the limitation of physical structure, the x-axis position X of the overhead cranel It must be smaller than the x-axis position X of the R crane. r If a work order is executed for each of the L and R cranes at the same time, the curves of their x positions changing with time t may be Figure 2 The solid line represents the position change line when the work order is running, and the dotted line represents that the overhead crane remains stationary when there is no work order being executed. The black point represents the starting point of the work order task, and the white point represents the end point of the work order task.

[0040] The lower line in the figure represents the change in the running position of the L overhead crane, and the upper line represents the change in the running position of the R overhead crane. The fact that the two overhead cranes can run at the same time is reflected in the figure that the two sets of lines cannot intersect. Figure 3 As shown in a, it means that the two overhead cranes cannot guarantee to run at the same time at any time. So the actual running position change should be Figure 3 As shown in b, the R overhead travelling car will wait for the L overhead travelling car to finish running before continuing to run its own work order.

[0041] The double solid line represents the process where a work order stops and waits for another work order to be executed. In order to propose a better collaborative solution for work order execution and make better use of this mathematical model, the work orders are classified so that the optimization strategies for the execution of different work orders can be more intuitively observed.

[0042] Work order classification: Consider the case where the starting position A of the work order is less than the ending position B, and the current position of the overhead crane is f. Figure 4 As shown in a:

[0043] The current position of the overhead crane can be divided into three situations: a position less than A, a position between A and B, and a position greater than B. The mathematical descriptions of these three work orders are Figure 4 bc corresponding.

[0044] When considering the case where the starting position A of the work order is greater than the ending position B, and the current position is f (the specific situation is as follows Figure 5 As shown), the corresponding mathematical description of the three work orders will be Figure 5 b, c, d. Work order classification and combination: In order to analyze the specific situation when two cranes work together, the above 6 work orders need to be classified and grouped. Figure 4 The situation on the left is named A1 work order. Figure 4 b and Figure 4 c is named as A2 work order; Figure 5 a and Figure 5 b is named as A2 work order, Figure 5 c is named A1 work order. So the execution routes of the four types of work orders are roughly as follows Figure 6 shown.

[0045] When two overhead cranes are running work orders at the same time, there will be 4×4 combinations of the four types of work orders, a total of 16 situations. In some of these situations, it can be guaranteed that the two cranes will not intersect. Figure 7 The seven situations shown are those in which no collision between the two vehicles occurs, wherein the combination representation (A1, A2) indicates that the L overhead travelling crane is an A1 type work order, and the R overhead travelling crane is an A2 type work order.

[0046] The rule of the situation is: if the R crane only moves to the right, there will be no collision. If the L crane only moves to the left, there will be no collision. The remaining 9 situations are all possible collision situations. As stated in the third condition of the premise of the mathematical model, the work of different cranes at the same position is equivalent (that is, the work at the same point is completed by different cranes at different times, and the effect is the same. For example, when the crane grabs and releases materials in the material yard, it is the same no matter which crane is used to complete it) Work order conversion strategy: First, let's look at the following four combinations, such as Figure 8 As shown, the work order execution routes of these four groups of overhead cranes intersect in the coordinate system, which means that in these four cases, no two work orders can run at the same time.

[0047] The strategy that can be used here is to exchange parts of the tasks of the two work orders. In the three cases (A1, B2), (A2, B1) and (A2, B2), the task end points of the two work orders can be exchanged; in the case of (B2, A2), the task start points of the two work orders can be exchanged, and then they will be as follows Fig. 9 As shown. Fig. 9 Relative to Figure 8 , the location of the work is the same, so the completed result is also the same, only the work order is modified.

[0048] Through observation, we can find Figure 8 The work orders that cannot be executed simultaneously as shown in the figure can now be executed by two overhead cranes at the same time without collision, and the execution efficiency of the work orders can be greatly accelerated.

[0049] Let's look at another situation. Fig.10 The case of the (A1, B1) work order combination is shown. However, this case should be discussed in two sub-cases. One is that at least one of the starting work points of the two work orders appears before the intersection of the work order execution path; the other is that both starting points appear after the intersection.

[0050] If at least one of the starting points of the two work orders appears before the intersection of the work order execution path, a single conversion (exchanging the end points of the two work orders) is sufficient; if both starting points are after the intersection, the starting and end points of the two work orders need to be exchanged at the same time. Fig.11 As shown in a and b.

[0051] In the remaining four cases, the conversion work cannot be completed directly by exchanging the starting or ending work points of the work order, so it is necessary to use the traditional method of pausing the work order to complete the task. However, if the task is completed by pausing the work order (such as Figure 3 c) violates the original intention of the invention to design this method, so other means can be used here to complete the same task, such as work order decomposition. Work order decomposition: This is different from the way of pausing the work order. If this method needs to be paused, the previously executed path will be directly regarded as a completed work order, and a pending work order can be regenerated for the unfinished part. For the four work orders A1, A2, B1 and B2, they can be divided into a sequential combination of multiple work orders. As Fig.12 As shown, each corresponds to one of the four work orders (A2 and B2 have two decomposition methods, but only one is needed here). By using the above four work order decomposition methods, the present invention can solve the conversion of the remaining four situations. The routes of the four work orders before conversion and the routes after conversion are as follows: Fig.13 As shown:

[0052] At this point, all work order combinations have been converted, and it can be observed that the results of all conversions will not weaken the efficiency of work order execution (executing the same task will only save time or keep the time the same). Work orders processed in this way can not only efficiently deal with position conflicts when multiple overhead cranes execute work orders at the same time, but also coordinate conflicting work orders without suspending the work orders.

Claims

1. A method for collaboratively executing work orders by multiple overhead cranes based on work order conversion, characterized in that: If there is a risk of crossover and conflict between the running paths of the two cranes in executing their respective work orders, part of the tasks of the two work orders will be exchanged to avoid crossover and conflict; Exchanging partial tasks of two work orders means exchanging the task end points of the two work orders, or exchanging the task start points of the two work orders; After the work orders are exchanged, a new work order is generated; The two overhead cranes continue to execute work order tasks according to the new work order.

2. The method for collaboratively executing work orders by multiple overhead cranes based on work order conversion according to claim 1 is characterized in that: If at least one of the starting work points of the two work orders appears before the intersection of the work order execution paths, the work order update is completed through one conversion; If both starting points are after the intersection point, the starting and ending points of the two work orders are swapped at the same time to complete the work order update.

3. The method for collaboratively executing work orders by multiple overhead cranes based on work order conversion according to claim 2 is characterized in that: If the conversion cannot be completed directly by exchanging the starting or ending work points of the work order, suspend one of the work orders to complete the task.

4. The method for collaboratively executing work orders by multiple overhead cranes based on work order conversion according to claim 3 is characterized in that: The suspension means that the previously executed path is directly regarded as a completed work order, and a to-do work order is newly generated for the uncompleted part.

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