Path planning method, system and transportation control system

Abstract

The present invention discloses a path planning method, system and transportation control system, wherein the path planning method includes the following steps: determining a feasible path according to the starting point and end point of a transport vehicle; determining the estimated travel time of the transport vehicle through each feasible path; when determining the estimated travel time, determining and selecting the feasible path with the shortest estimated travel time as the optimal path according to the static time, dynamic time of each line segment of the feasible path and the static time between each line. When performing path planning, the present invention estimates the travel time of the transport vehicle through each feasible path according to the dynamic situation of each feasible path, and selects the feasible path with the shortest estimated travel time as the optimal path. When determining the estimated travel time, not only the static time of the transport vehicle passing normally is considered, but also the delay that may be caused by the existing transport vehicles in different line segments of each feasible path is considered, which effectively improves the accuracy of path planning and is conducive to improving travel efficiency.

Description

Technical Field

[0001] The present invention relates to the field of automatic material handling systems in semiconductor processing, and in particular to a path planning method and system for a transport vehicle and a transport control system. Background Art

[0002] Automatic Material Handling System (AMHS) plays a vital role in the transportation and equipment layout of semiconductor materials. The automatic material handling system includes a variety of structures, such as overhead crane handling system, AGV handling system, etc. Whether it is an overhead crane or AGV, their main responsibility is to move materials from the starting point to the end point according to the planned path according to instructions. Reasonable planning of their moving paths can effectively improve the efficiency and speed of material handling, which is conducive to improving production efficiency.

[0003] When performing path planning, the conventional approach is to use the Dijkstra algorithm, A-Star algorithm, etc. to find the shortest path between the starting point and the end point. These shortest path planning algorithms are based on the fixed distance / weight between nodes, so they are also called static shortest path planning algorithms.

[0004] However, the actual situation is that the status on the track is constantly changing. For example, there is a high density of overhead cranes on the optimal path, there is local congestion, or there are many overhead cranes loading and unloading, all of which will greatly increase the actual travel time of the overhead cranes through the optimal path.

[0005] Therefore, the optimal path determined by the static shortest path planning algorithm is often not the most efficient path. Summary of the invention

[0006] The purpose of the present invention is to solve the above problems existing in the prior art and to provide a path planning method, system and transportation control system.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] The path planning method comprises the following steps:

[0009] Determine a starting point of a transport vehicle and its end point to which it is to move;

[0010] Determine a feasible path for the transport vehicle to move from the starting point to the end point;

[0011] Determine the estimated travel time of the transport vehicle through each feasible path; when determining the estimated travel time of the transport vehicle through a feasible path, sum the static time and dynamic time of all route segments of the feasible path and the static time between all routes of the feasible path to obtain the estimated travel time of the transport vehicle through a feasible path; the static time of a route segment is the theoretical time for the transport vehicle to pass through the route segment at a set speed; the dynamic time of a route segment is the sum of the first delay times corresponding to all transport vehicles currently located between the starting point and the end point at the route segment when determining the estimated travel time of the transport vehicle through the feasible path;

[0012] From the feasible paths, the one with the shortest estimated travel time is selected as the optimal path.

[0013] Preferably, the first delay time corresponding to a transport vehicle at a line segment is updated according to the following formula:

[0014] ;

[0015] W t+1 represents the first delay time corresponding to a transport vehicle at a line segment obtained by the t+1th update;

[0016] W t represents the first delay time corresponding to a transport vehicle at the line segment obtained by the t-th update;

[0017] Alpha represents the learning rate, which ranges from 0 to 1;

[0018] T real represents the time taken by the transport vehicle passing through the line segment when the first delay time corresponding to a transport vehicle at the line segment is updated for the t+1th time;

[0019] W static represents the static time of the line segment;

[0020] N represents the number of transport vehicles already on the line segment when the transport vehicles passing through the line segment start to enter the line segment when the first delay time corresponding to a transport vehicle on the line segment is updated for the t+1th time.

[0021] Preferably, when determining T real When the first delay time corresponding to a transport vehicle at the line segment is updated for the t+1th time, the actual time taken by the transport vehicle passing through the line segment to pass through the line segment is subtracted from the idle waiting time of the transport vehicle passing through the line segment at the line segment.

[0022] Preferably, when determining the estimated travel time of a transport vehicle through a feasible path, the second delay time of each route segment of the feasible path is also added. The second delay time of one route segment is the sum of the delays corresponding to all transport vehicles that are not currently at the route segment and whose determined optimal path includes the route segment when determining the estimated travel time of a transport vehicle at the starting point through a feasible path including the route segment.

[0023] Preferably, when determining the estimated travel time of a transport vehicle at the starting point through a feasible path including the line segment, the delay corresponding to each transport vehicle that is not currently at the line segment and the determined optimal path includes the line segment is equal to the first delay time corresponding to a transport vehicle at the line segment obtained by the latest update.

[0024] Preferably, when determining the estimated travel time of the transport vehicle through a feasible path, the total travel time of each route segment of the feasible path is determined based on the transport vehicle density coefficient, static time, dynamic time and second delay time of each route segment of the feasible path, and the total travel time of all route segments of a feasible path and the static time between all routes of the feasible path are summed to obtain the estimated travel time of the transport vehicle through a feasible path.

[0025] Preferably, the total travel time of a route segment of a feasible path is determined according to the following formula:

[0026] ;

[0027] Among them, W line Represents the total travel time of a route segment of a feasible path;

[0028] W static represents the static time of the line segment;

[0029] W t+1 represents the first delay time corresponding to a transport vehicle at the line segment obtained by the t+1th update;

[0030] N in represents the number of transport vehicles currently at the route segment and between the start point and the end point when determining the estimated travel time of the transport vehicle at the start point through a feasible path including the route segment;

[0031] N out represents the number of transport vehicles that are not currently at the route segment and whose determined optimal path includes the route segment when determining the estimated travel time of the transport vehicle at the starting point through a feasible path including the route segment;

[0032] r represents the transport vehicle density coefficient of the line segment.

[0033] Preferably, when the starting point is located in the middle of a line segment, the transport vehicle density coefficient of the line segment is determined according to the following formula;

[0034] r=N in / (L1 / L2);

[0035] When the transport vehicle needs to completely pass through a route segment of a feasible path and when the end point is located in the middle of a route segment, the transport vehicle density coefficient of the route segment is determined according to the following formula;

[0036] r = (N in +N out ) / (L3 / L2);

[0037] Among them, N in N represents the number of transport vehicles currently at the route segment and between the starting point and the end point when determining the estimated travel time of the transport vehicle at the starting point through a feasible path including the route segment; out It indicates the number of transport vehicles that are not currently at the route segment and whose determined optimal path includes the route segment when determining the estimated travel time of the transport vehicle at the starting point through a feasible path including the route segment. L1 indicates the distance between the starting point and the bifurcation point of the route segment; L2 indicates the preset track length occupied by the transport vehicle; and L3 is the length of the route segment.

[0038] Path planning system, including:

[0039] A starting point and end point determination unit, used to determine a starting point of a transport vehicle and an end point to which it is to move;

[0040] A feasible path determination unit, used to determine a feasible path for the transport vehicle to move from a starting point to an end point;

[0041] A travel time estimation unit, used to determine the estimated travel time of the transport vehicle through each feasible path; when determining the estimated travel time of the transport vehicle through a feasible path, it is determined according to the static time, dynamic time of each route segment of the feasible path and the static time between routes; the static time of one route segment is the theoretical time taken by the transport vehicle to pass through the route segment at a set speed; the dynamic time of one route segment is the sum of the first delay times corresponding to all transport vehicles currently located between the starting point and the end point at the route segment when determining the estimated travel time of the transport vehicle through the feasible path;

[0042] The optimal path determination unit is used to select one of the feasible paths with the shortest estimated travel time as the optimal path.

[0043] A transportation control system includes a memory and a processor, wherein the memory stores a program executable by the processor, and when the program is executed, any of the above-mentioned path planning methods is implemented.

[0044] The advantages of the technical solution of the present invention are mainly reflected in:

[0045] When performing path planning, the present invention estimates the travel time of the transport vehicle through each feasible path according to the dynamic situation of each feasible path, thereby selecting the feasible path with the least estimated travel time as the optimal path, and when determining the estimated travel time, not only the static time of the normal passage of the transport vehicle is considered, but also the delay that may be caused by the existing transport vehicles in different line sections of each feasible path is further considered, effectively avoiding the deficiency of the existing static shortest path planning algorithm that does not take into account the dynamic change of the state of the feasible line, effectively improving the accuracy of path planning, and helping to improve the travel efficiency. At the same time, the development difficulty and implementation difficulty of this path planning method are greatly reduced.

[0046] When determining the dynamic time of each line segment, the present invention updates the first delay time corresponding to the transport vehicle at a line segment in real time according to the algorithm, thereby ensuring that the dynamic time of each line segment can be consistent with the real-time traffic conditions of each line segment to ensure the accuracy of time estimation.

[0047] When performing path planning, the present invention further considers the delay caused by the transport vehicles that will move to each line segment of the feasible path in the future, so that the estimated travel time of each feasible path can be more accurate.

[0048] When determining the estimated travel time of each feasible path, the present invention further considers the impact of the congestion of each route segment on the travel time, which is conducive to more accurate determination of the travel time, thereby making the path planning more accurate. In addition, when planning the path, the feasible paths of the route segments with a higher transport vehicle density coefficient are preferentially excluded, which effectively avoids the long-term congestion of transport vehicles in individual route segments affecting the overall transport efficiency, and is also conducive to alleviating congestion. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a schematic diagram of the track of the overhead travelling crane transport system of the present invention;

[0050] Figure 2 is a flow chart of the path planning method of the present invention;

[0051] Figure 3 It is a schematic diagram of the overhead travelling crane of the present invention that needs to move to a point on a track section to unload cargo;

[0052] Figure 4 is a schematic diagram of the overhead travelling crane of the present invention moving through a line section;

[0053] Figure 5 This is an example diagram of determining the second delay time of a line segment in the present invention. DETAILED DESCRIPTION

[0054] The purpose, advantages and features of the present invention will be illustrated and explained by the non-limiting description of the following preferred embodiments. These embodiments are only typical examples of the application of the technical solution of the present invention, and any technical solution formed by equivalent replacement or equivalent transformation falls within the scope of protection claimed by the present invention.

[0055] In the description of the scheme, it should be noted that the terms "center", "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience and simplification of description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance. Example 1

[0056] The path planning method disclosed in the present invention is explained below in conjunction with the accompanying drawings. The path planning method is based on a known material handling system. For example, the material handling system is an overhead crane handling system (OHT, Overhead Hoist Transfer) and / or an AGV handling system, etc. Their specific structures are known technologies and will not be described in detail here.

[0057] In the following, an overhead crane handling system is used as an example for explanation. The overhead crane handling system generally includes a track suspended under the ceiling and an overhead crane moving along the track. The overhead crane is a handling vehicle. When the material handling system is an AGV handling system, the AGV is the handling vehicle.

[0058] The specific layout of the track can be designed according to actual needs. Figure 1 The specific layout of a track is shown, and the overhead travelling vehicle travels in one direction on the track. Figure 1 The arrow on the straight line in the middle shows the moving direction of the overhead travelling vehicle on the track. At the same time, there are several points on the track, which can be divided into bifurcation points, confluence points and common points. The bifurcation point refers to the point after which the track bifurcates into two paths. Figure 1 Points 4, 67, and 88 in the figure are bifurcations. The confluence point refers to a point after two bifurcated paths merge, such as Figure 1Points 12, 63, and 66 are confluence points; the common points are other points other than bifurcation points and confluence points, such as the Figure 1 Points 13, 14, and 15 are common points. In the direction of travel, the track from a confluence point to the next fork point is defined as a line segment. Figure 1 In the example, the track between point 12 (merging point) and point 28 (forking point) is a line segment, which is expressed as line segment (12->28); for example, the track between point 40 (merging point) and point 42 (forking point) is a line segment, which is expressed as line segment (40->42). At the same time, the area between line segments is defined as the line interval, which can be understood as the track between a forking point and the next merging point in the driving direction, for example, Figure 1 In the diagram, the track between point 42 (fork point) and point 12 (merge point) is one line room.

[0059] At the same time, each overhead crane can determine the position to which it moves in a known manner and communicate with the TCS (Transportation Control System) in a known manner such as wireless communication or network communication. The TCS determines the overhead crane to perform the transportation according to the transportation requirements, plans a path for it, and controls the overhead crane to complete the transportation. The overhead crane executes the transportation instruction according to the control instruction of the TCS, and the overhead crane feeds back its position and working status to the TCS in real time during the movement. The corresponding technology is a known technology and will not be described in detail here.

[0060] Correspondingly, as attached Figure 2 As shown, the path planning method includes the following steps:

[0061] Determine the starting point of the vehicle and the end point to which it will move, wherein the starting point and the end point are both points set on the track. Furthermore, the starting point and the end point can be determined according to different scenarios.

[0062] For example, when a crane is needed to execute a transport instruction, the starting point may be the current location of each idle crane, and the end point is the location of the material to be transported by the transport instruction. At this time, there may be multiple starting points, but only one end point.

[0063] When it is necessary to control a crane to transport the material it currently grabs to the target location, the starting point is the current location of the crane or the current location of the material, and the end point is the target location to which the material needs to be transported. At this time, there is only one starting point and one end point. In this scenario, a path can be planned for the crane before the crane reaches the location of the material. At this time, the starting point is the current location of the material to be transported. Of course, the path can also be planned for the crane when the crane reaches the material to be transported.

[0064] When the overhead crane completes unloading and needs to move from its current position to a position to stop and wait for a call, the starting point is also the current position of the overhead crane, and the end point is the position where the overhead crane needs to stop. At this time, there is only one starting point and there can be multiple end points.

[0065] Determine the feasible paths for the overhead crane to move from the starting point to the end point. The feasible paths are all the paths connecting the starting point and the end point. A feasible path may include one or more line segments. When multiple line segments are included, a feasible path also includes one or more line intervals. For example, when an overhead crane needs to move from point 28 (starting point) to point 56 (end point), the overhead crane has at least three feasible paths. The first feasible path is from point 28 to point 56 via point 39, point 47, point 80, point 81, point 82, point 83, and point 55 in sequence; the second path is from point 28 to point 56 via point 39, point 47, point 105, and point 110 in sequence. 06, point 107, point 108, point 109, point 110, point 111 move to point 56; the third path is from point 28 through point 29, point 30, point 31, point 32, point 33, point 100, point 101, point 102, point 103, point 104, point 52, point 53, point 54, point 55 to point 56.

[0066] Determine the estimated travel time of the overhead traveling vehicle through each feasible path.

[0067] When determining the estimated travel time of the overhead crane through a feasible path, it is determined based on the static time and dynamic time of each line segment of the feasible path and the static time between each line of the feasible path; when specifically calculating, the static time and dynamic time of all line segments of the feasible path and the static time between all lines of the feasible path are summed to obtain the estimated travel time of the overhead crane through a feasible path.

[0068] Among them, the static time of a line segment of the feasible path refers to the theoretical time taken by the overhead crane to pass through the line segment at the set speed when there is no other overhead crane on the line segment. The overhead crane passing through a line segment usually means that the overhead crane moves from the confluence point of the line segment to the bifurcation point of the line segment. Since the moving speed of the track in the turning section and the straight section is different, it is necessary to calculate the theoretical time according to the specific speed of different track sections. For example, an overhead crane needs to move through the line segment (12->28), and the track between point 12 and point 13 and the track between point 27 and point 28 are both turning sections, and the track between point 13 and point 27 is a straight section. Assuming that the lengths of the two turning sections are L 弯 , the length of the straight line segment is L 直 , the speed of the overhead crane in the turning section is V 弯 , the speed in the straight line is V 直 , then the theoretical time for the overhead travelling vehicle to pass the route section (12->28) at the set speed = 2L 弯 / V 弯 +L 直 / V 直 . And, if the starting point is located between the two ends of a line segment, for example, the starting point is located at point 14 of line segment (12->28), and the distance between point 14 and point 27 is L 起 , then the overhead crane passing the line segment (12->28) means that the overhead crane moves from point 14 to point 28. Correspondingly, the theoretical time = L 弯 / V 弯 +L 起 / V 直 .

[0069] Correspondingly, when determining the estimated travel time of the overhead crane through a feasible path, it is necessary to sum the static time of all line segments of the feasible path to obtain the total static time of the overhead crane at the starting point passing through all line segments of the feasible path. For example, a feasible path includes 3 line segments, and the static time of the 3 line segments is 10 seconds, 15 seconds and 20 seconds respectively. The static time of the 3 line segments is summed to 10+15+20=45 seconds, so that the total static time of the overhead crane at the starting point passing through all line segments of the feasible path is determined to be 45 seconds.

[0070] The dynamic time of a line segment of a feasible path reflects the influence of various factors existing on the line segment on the passage of the overhead crane through the line segment. The various factors existing on the line segment include, for example, other overhead cranes are picking up or unloading goods on the line segment, or there are a large number of overhead cranes on the line segment causing congestion.

[0071] When determining the dynamic time of a line segment of the feasible path, the first delay times corresponding to all overhead traveling vehicles currently located between the starting point and the end point at the line segment are summed.

[0072] The first delay time corresponding to an overhead traveling vehicle at the line segment changes with the actual time taken by each overhead traveling vehicle to pass through the line segment. When the line segment is congested, the first delay time will increase, and when the line segment is idle, the first delay time will decrease and approach 0. Furthermore, when an overhead traveling vehicle moves through the line segment, the first delay time corresponding to the overhead traveling vehicle at the line segment is updated according to the time taken by the overhead traveling vehicle to pass through the line segment.

[0073] Specifically, the first delay time corresponding to a crane at a line section is updated according to the following formula:

[0074] ;

[0075] Among them, W t+1 represents the first delay time corresponding to an overhead travelling vehicle at the line segment obtained by the t+1th update;

[0076] W t represents the first delay time corresponding to a crane at the line segment obtained by the tth update. Initially, W t is 0;

[0077] Alpha represents the learning rate, which takes a value between 0 and 1; it can represent the sensitivity to the congestion change of the line segment, and the preferred value of alpha is 0.1.

[0078] T real represents the time taken by the overhead travelling vehicle passing through the line segment when the first delay time corresponding to an overhead travelling vehicle at the line segment is updated for the t+1th time; and, when determining T real When the first delay time corresponding to an overhead travelling vehicle at the line segment is updated for the t+1th time, the actual time taken by the overhead travelling vehicle passing through the line segment to pass through the line segment is subtracted from the idle standby time of the overhead travelling vehicle passing through the line segment in the line segment.

[0079] As attached Figure 3As shown, the overhead crane V01 enters the line section (1001->1010) from point 1001 and unloads at point 1005. After the overhead crane V01 completes unloading at point 1005, it waits in place, and after waiting for 10 seconds, it receives a new instruction from TCS to start moving to point 1010 and pass through the line section (1001->1010). At this time, the idle standby time (10 seconds) of the overhead crane V01 at point 1005 cannot be used as the time for the overhead crane V01 to pass through the line section (1001->1010). Therefore, when determining T real When the crane V01 passes through the line segment (1001->1010), 10 seconds is subtracted from the actual time it takes the crane V01 to pass through the line segment (1001->1010). Therefore, TCS needs to distinguish between the crane's idle standby time and moving time according to the crane's operating status.

[0080] W static It represents the static time of the line segment, that is, the theoretical time taken by the overhead travelling crane to pass through the line segment at the set speed.

[0081] N represents the number of existing overhead cranes on the line segment when the first delay time corresponding to an overhead crane at the line segment is updated for the t+1th time. When the overhead crane passing through the line segment begins to enter the line segment, 1 is added as a smoothing factor to solve the problem that when there is no overhead crane on the line segment, N=0 and the first delay time cannot be calculated by the above formula.

[0082] [(T real -W static ) / (N+1)-W t ] represents the change of the first delay time corresponding to the overhead crane between time t+1 and time t.

[0083] For example, as shown in the attached Figure 4 As shown in FIG. 1 , when the overhead crane V01 enters a line segment, there are two overhead cranes in front of it. If the time taken by the overhead crane V01 to pass through the line segment is 30 seconds, and the theoretical time taken by the overhead crane V01 to pass through the line segment according to the set speed is 10 seconds, assuming that W t is 1 second, alpha is 0.1, then when the overhead crane V01 passes through the line segment, the first delay time W corresponding to an overhead crane at the line segment obtained by the t+1th update t+1 =1+0.1*[(30-10) / (2+1)-1]=1+0.1*(6.67-1)=1+0.57=1.57 seconds. Therefore, before the first delay time is updated next time, the first delay time corresponding to all overhead traveling vehicles currently located on the line segment is uniformly calculated as 1.57 seconds, that is, if it is necessary to determine the estimated travel time of the overhead traveling vehicle through a feasible path including the line segment at this time, the dynamic time of the line segment is calculated based on 1.57 seconds.

[0084] The following example illustrates how to determine the dynamic time of a line segment of a feasible path. Assume that there are four overhead cranes at the line segment, and only two overhead cranes are located between the starting point and the end point, that is, two overhead cranes are located in front of the starting point. These two overhead cranes will affect the travel time of the overhead crane at the starting point. Assume that the first delay time W corresponding to a crane at the line segment obtained by the t+1th update is t+1 =1.57 seconds, then the dynamic time of the line segment is determined to be 2*W t+1 =2*1.57=3.14 seconds.

[0085] Of course, if the four overhead traveling vehicles of the line segment are all located between the starting point and the end point, the dynamic time of the line segment is determined to be 4*W. t+1 =4*1.57=6.28 seconds.

[0086] When determining the estimated travel time of the overhead crane through a feasible path, the dynamic times of all line segments of the feasible path need to be added together as the total dynamic time of the overhead crane through all line segments of the feasible path.

[0087] For example, if a feasible path consists of four segments, and the dynamic time of each segment is 2*W t+1 , then the total dynamic time of the overhead travelling vehicle passing through all line segments of the feasible path is 4*2*W t+1 .

[0088] The passage between the lines is controlled by the ZCU (Zone Control Unit). To prevent conflicts, only one overhead crane is allowed to pass between the lines at any time, and there is no additional interference in the passing time. Therefore, the static time between each line (the time it takes for an overhead crane to pass through a line at a predetermined speed) is often fixed and does not need to be learned. Therefore, the static time for the overhead crane to pass through each line can be set to a fixed value based on the actual time it takes for the overhead crane to pass through a line, and is not limited here.

[0089] When determining the estimated travel time of the overhead crane through a feasible path, the main consideration is that the overhead crane at the starting point needs to pass through several routes and the static time between each route when passing through a feasible path. Assuming that the overhead crane at the starting point needs to pass through 2 routes when passing through a feasible path, and assuming that the static time between the two routes is 2 seconds, then when calculating the estimated travel time of the overhead crane at the starting point through the feasible path, the total static time of the overhead crane at the starting point passing through all routes of the feasible path is determined to be 2*2=4 seconds.

[0090] The above method for determining the estimated travel time of the overhead crane through a feasible path only considers the influence of the overhead crane currently existing at each line segment of the feasible path and located between the starting point and the end point on the travel time, but does not consider the influence of the overhead crane that is not currently at a line segment but the determined optimal path includes the line segment on the congestion level of each line segment when determining the estimated travel time of the overhead crane at the starting point through a feasible path including the line segment.

[0091] Therefore, when determining the estimated travel time of the overhead crane through a feasible path, the second delay time of each line segment is also considered, that is, when determining the estimated travel time of the overhead crane through a feasible path, it is necessary to further add the second delay time of all line segments of the feasible path on the basis of calculating the sum of the total static time, the total dynamic time of the overhead crane passing through all line segments of the feasible path and the total static time of the overhead crane passing through all lines of the feasible path.

[0092] The second delay time of a line segment is the sum of the delays corresponding to all the overhead travelling vehicles which are not currently at the line segment but whose determined optimal path includes the line segment when determining the estimated travel time of the overhead travelling vehicle at the starting point through a feasible path including the line segment.

[0093] For the convenience of calculation, when determining the estimated travel time of the overhead travelling vehicle at the starting point through a feasible path including the line segment, the delay corresponding to each overhead travelling vehicle that is not currently on the line segment but has the determined optimal path including the line segment is equal to the first delay time corresponding to the overhead travelling vehicle at the line segment obtained by the latest update.

[0094] For example, as shown in the attached Figure 5 As shown, when planning the path for the overhead traveling vehicle at the starting point, a feasible path is determined to include the line segment (1002->1013). At this time, it is determined that the overhead traveling vehicle V01 is not on the line segment, and the optimal path of the overhead traveling vehicle V01 that has been determined includes the line segment (1002->1013). Therefore, when determining the second delay time of the line segment (1002->1013), the delay corresponding to the overhead traveling vehicle V01 needs to be added. Assuming that when determining the estimated travel time of the overhead traveling vehicle at the starting point through a feasible path that includes the line segment, the overhead traveling vehicle that is not currently on the line segment (1002->1013), but the determined optimal path includes the line segment (1002->1013) has and only has the overhead traveling vehicle V01, and the first delay time corresponding to the overhead traveling vehicle at the line segment (1002->1013) that is obtained by the latest update is equal to 2 seconds, then the second delay time of the line segment (1002->1013) is determined to be 2 seconds.

[0095] Furthermore, the density of the overhead cranes in each line segment is also a key factor affecting the time it takes for the overhead cranes to pass through the line segment. Therefore, when determining the estimated travel time of the overhead cranes through a feasible path, the estimated travel time is also determined based on the overhead crane density coefficient (transporter density coefficient) of each line segment of the feasible path. And the overhead crane density coefficient of each line segment can be greater than 1. At this time, the line segment will be very crowded, which means that there will be a large delay when the overhead crane passes through the line segment. Therefore, when determining a feasible path, it is necessary to avoid the path including such a line segment as much as possible. For example, if the overhead crane density coefficient of a line segment of a feasible path is greater than 1, then the feasible path is directly ignored.

[0096] When determining the estimated travel time of the overhead crane at the starting point through a feasible path, the total travel time of each line segment of the feasible path is determined according to the overhead crane density coefficient, static time, dynamic time and second delay time of each line segment of the feasible path, and the total travel time of all line segments of a feasible path and the static time between all lines of the feasible path are summed to obtain the estimated travel time of the overhead crane through a feasible path.

[0097] Specifically, the total travel time of a line segment of a feasible path is determined according to the following formula:

[0098] ;

[0099] Among them, W line Represents the total travel time of a route segment of a feasible path;

[0100] W static represents the static time of the line segment;

[0101] W t+1 represents the first delay time corresponding to an overhead travelling vehicle at the line segment obtained by the t+1th update;

[0102] N in represents the number of overhead travelling vehicles currently at the route segment and between the start point and the end point when determining the estimated travel time of the overhead travelling vehicle at the start point through a feasible path including the route segment;

[0103] N out represents the number of overhead cranes that are not currently at the line segment and whose determined optimal path includes the line segment when determining the estimated travel time of the overhead crane at the starting point through a feasible path including the line segment;

[0104] r represents the overhead travelling crane density coefficient of the line section.

[0105] For example, the first delay time corresponding to a crane at the line segment obtained by the t+1th update is 2 seconds, and Nin =2, N out = 1, the overhead travelling vehicle density coefficient of the line section is r = 0.5, W static = 10 seconds. Then the total travel time of the overhead travelling vehicle at the starting point through the line section = 10 + (2*2 + 1*2) * 0.5 = 10 + 6 * 0.5 = 13 seconds.

[0106] The overhead travelling vehicle density coefficient for each line segment on a feasible path needs to be calculated separately according to the locations of the starting point and the end point:

[0107] For example, when the starting point is located in the middle of a line segment of a feasible path, that is, the starting point is between the confluence point and the bifurcation point of the line segment, at this time, the overhead crane at the starting point does not need to pass through the line segment completely, and the subsequent overhead crane entering the line segment will not affect the moving speed of the overhead crane at the starting point. Therefore, the overhead crane density coefficient of the line segment is determined according to the following formula;

[0108] r=N in / (L1 / L2).

[0109] When the overhead travelling crane at the starting point needs to completely pass through a line segment of a feasible path, the overhead travelling crane density coefficient of the line segment is determined according to the following formula;

[0110] r = (N in +N out ) / (L3 / L2);

[0111] When the end point is located in the middle of a line segment, the overhead travelling crane density coefficient of the line segment is determined according to the following formula;

[0112] r = (N in +N out ) / (L3 / L2);

[0113] Among them, N in N represents the number of overhead travelling vehicles currently at the line segment and between the starting point and the end point when determining the estimated travel time of the overhead travelling vehicle at the starting point through a feasible path including the line segment; out It indicates the number of overhead cranes that are not currently at the line segment and whose determined optimal path includes the line segment when determining the estimated travel time of the overhead crane at the starting point through a feasible path including the line segment. L1 indicates the distance between the starting point and the bifurcation point of the line segment; L2 indicates the preset track length occupied by the overhead crane; and L3 is the length of the line segment.

[0114] For example, the length of a line segment is 5 meters, and it is assumed that the preset track length occupied by the overhead crane is 0.8 meters (the preset track length occupied by the overhead crane is not the actual track length occupied by the overhead crane, and can be set as needed, but needs to be greater than the actual length of the overhead crane), then the maximum number of overhead cranes that can be accommodated in the line segment = 5 / 0.8 = 7 (rounded up, this is because some line segments are too short and the actual number of overhead cranes that can be accommodated is 0).

[0115] Therefore, assuming that a feasible path planned for an overhead crane includes the line segment, and the overhead crane needs to pass through the line segment completely, if there are currently 4 overhead cranes at the line segment; at the same time, there is currently 1 overhead crane that is not at the line segment and the determined optimal path includes the line segment, then the overhead crane density coefficient of the line segment = (4+1) / 7≈0.71.

[0116] After determining the estimated travel time of the overhead crane through each feasible path, the one with the shortest estimated travel time is selected from the feasible paths as the optimal path. For example, if there are three feasible paths, the estimated travel time of the overhead crane through the first feasible path is 30 seconds, the estimated travel time of the overhead crane through the second feasible path is 32 seconds, and the estimated travel time of the overhead crane through the third feasible path is 35 seconds, then the first feasible path is selected as the optimal path for the overhead crane to move from the starting point to the end point.

[0117] Furthermore, after the overhead crane has moved for a period of time according to the determined optimal path, the current position of the overhead crane can be used as the starting point, and the optimal path can be determined again according to the above process, so that the latest optimal path can effectively match the latest status on the track to improve the efficiency of the overhead crane transportation. Example 2

[0118] This embodiment discloses a path planning system, including:

[0119] A starting point and end point determination unit, used to determine a starting point of a transport vehicle and an end point to which it is to move;

[0120] A feasible path determination unit, used to determine a feasible path for the transport vehicle to move from a starting point to an end point;

[0121] A travel time estimation unit, used to determine the estimated travel time of the transport vehicle through each feasible path; when determining the estimated travel time of the transport vehicle through a feasible path, it is determined according to the static time, dynamic time of each route segment of the feasible path and the static time between routes; the static time of one route segment is the theoretical time taken by the transport vehicle to pass through the route segment at a set speed; the dynamic time of one route segment is the sum of the first delay times corresponding to all transport vehicles currently located between the starting point and the end point at the route segment when determining the estimated travel time of the transport vehicle through the feasible path;

[0122] The optimal path determination unit is used to select one of the feasible paths with the shortest estimated travel time as the optimal path. Example 3

[0123] This embodiment discloses a transportation control system, including a memory and a processor, wherein the memory stores a program executable by the processor, and when the program is executed, the path planning method described above is implemented.

[0124] There are many implementation methods of the present invention, and all technical solutions formed by equivalent transformation or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A path planning method, characterized in that: The steps include: Determine a starting point of a transport vehicle and its end point to which it is to move; Determine a feasible path for the transport vehicle to move from the starting point to the end point; Determining an estimated travel time for the transport vehicle to pass through each feasible path; When determining the estimated travel time of the transport vehicle through a feasible path, the static time and dynamic time of all route segments of the feasible path and the static time between all routes of the feasible path are summed to obtain the estimated travel time of the transport vehicle through the feasible path; the static time of one route segment is the theoretical time taken by the transport vehicle to pass through the route segment at a set speed; the dynamic time of one route segment is the sum of the first delay times corresponding to all transport vehicles currently located between the starting point and the end point at the route segment when determining the estimated travel time of the transport vehicle through the feasible path; The first delay time corresponding to a transport vehicle at a line segment is updated according to the following formula: ； W t+1 represents the first delay time corresponding to a transport vehicle at a line segment obtained by the t+1th update; W t represents the first delay time corresponding to a transport vehicle at the line segment obtained by the t-th update; Alpha represents the learning rate, which ranges from 0 to 1; T real represents the time taken by the transport vehicle passing through the line segment when the first delay time corresponding to a transport vehicle at the line segment is updated for the t+1th time; W static represents the static time of the line segment; N represents the number of transport vehicles already on the line segment when the transport vehicles passing through the line segment begin to enter the line segment when the first delay time corresponding to a transport vehicle on the line segment is updated for the t+1th time; From the feasible paths, the one with the shortest estimated travel time is selected as the optimal path.

2. The path planning method according to claim 1, characterized in that: In determining T real When the first delay time corresponding to a transport vehicle at the line segment is updated for the t+1th time, the actual time taken by the transport vehicle passing through the line segment to pass through the line segment is subtracted from the idle waiting time of the transport vehicle passing through the line segment at the line segment.

3. The path planning method according to claim 1, characterized in that: When determining the estimated travel time of the transport vehicle through a feasible path, the second delay time of each route segment of the feasible path is also added. The second delay time of one route segment is the sum of the delays corresponding to all transport vehicles that are not currently at the route segment and whose determined optimal path includes the route segment when determining the estimated travel time of the transport vehicle at the starting point through a feasible path including the route segment.

4. The path planning method according to claim 3, characterized in that: When determining the estimated travel time of a transport vehicle at the starting point through a feasible path including the line segment, the delay corresponding to each transport vehicle that is not currently at the line segment and the determined optimal path includes the line segment is equal to the first delay time corresponding to a transport vehicle at the line segment obtained by the most recent update.

5. The path planning method according to any one of claims 1 to 4, characterized in that: When determining the estimated travel time of the transport vehicle through a feasible path, the total travel time of each route segment is determined based on the transport vehicle density coefficient, static time, dynamic time and second delay time of each route segment of the feasible path, and the total travel time of all route segments of a feasible path and the static time between all routes of the feasible path are summed to obtain the estimated travel time of the transport vehicle through a feasible path.

6. The path planning method according to claim 5, characterized in that: The total travel time of a route segment of a feasible path is determined according to the following formula: ； Among them, W line Represents the total travel time of a route segment of a feasible path; W static represents the static time of the line segment; W t+1 represents the first delay time corresponding to a transport vehicle at the line segment obtained by the t+1th update; N in represents the number of transport vehicles currently at the route segment and between the start point and the end point when determining the estimated travel time of the transport vehicle at the start point through a feasible path including the route segment; N out represents the number of transport vehicles that are not currently at the route segment and whose determined optimal path includes the route segment when determining the estimated travel time of the transport vehicle at the starting point through a feasible path including the route segment; r represents the transport vehicle density coefficient of the line segment.

7. The path planning method according to claim 5, characterized in that: When the starting point is located in the middle of a line segment, the transport vehicle density coefficient of the line segment is determined according to the following formula; r=N in / (L1 / L2); When the transport vehicle needs to completely pass through a route segment of a feasible path and when the end point is located in the middle of a route segment, the transport vehicle density coefficient of the route segment is determined according to the following formula; <h2 style=";text-align:left;direction:ltr">r=(N)<h2 style=";text-align:left;direction:ltr"> in <h2 style=";text-align:left;direction:ltr"> +N<h2 style=";text-align:left;direction:ltr"> out <h2 style=";text-align:left;direction:ltr"> ( / (L3 / L2)); Among them, N in N represents the number of transport vehicles currently at the route segment and between the starting point and the end point when determining the estimated travel time of the transport vehicle at the starting point through a feasible path including the route segment; out It indicates the number of transport vehicles that are not currently at the route segment and whose determined optimal path includes the route segment when determining the estimated travel time of the transport vehicle at the starting point through a feasible path including the route segment. L1 indicates the distance between the starting point and the bifurcation point of the route segment; L2 indicates the preset track length occupied by the transport vehicle; and L3 is the length of the route segment.

8. A path planning system, characterized in that: These include: A starting point and end point determination unit, used to determine a starting point of a transport vehicle and an end point to which it is to move; A feasible path determination unit, used to determine a feasible path for the transport vehicle to move from a starting point to an end point; A travel time estimation unit, used to determine the estimated travel time of the transport vehicle through each feasible path; When determining the estimated travel time of the transport vehicle through a feasible path, the static time and dynamic time of all route segments of the feasible path and the static time between all routes of the feasible path are summed to obtain the estimated travel time of the transport vehicle through the feasible path; the static time of one route segment is the theoretical time taken by the transport vehicle to pass through the route segment at a set speed; the dynamic time of one route segment is the sum of the first delay times corresponding to all transport vehicles currently located between the starting point and the end point at the route segment when determining the estimated travel time of the transport vehicle through the feasible path; The first delay time corresponding to a transport vehicle at a line segment is updated according to the following formula: ； W t+1 represents the first delay time corresponding to a transport vehicle at a line segment obtained by the t+1th update; W t represents the first delay time corresponding to a transport vehicle at the line segment obtained by the t-th update; Alpha represents the learning rate, which ranges from 0 to 1; T real represents the time taken by the transport vehicle passing through the line segment when the first delay time corresponding to a transport vehicle at the line segment is updated for the t+1th time; W static represents the static time of the line segment; N represents the number of transport vehicles already on the line segment when the transport vehicles passing through the line segment begin to enter the line segment when the first delay time corresponding to a transport vehicle on the line segment is updated for the t+1th time; The optimal path determination unit is used to select one of the feasible paths with the shortest estimated travel time as the optimal path.

9. A transportation control system, comprising a memory and a processor, wherein the memory stores a program executable by the processor, characterized in that: When the program is executed, the path planning method as described in any one of claims 1 to 7 is implemented.

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