CN115147042A

CN115147042A - Traffic control system and method

Info

Publication number: CN115147042A
Application number: CN202210710024.0A
Authority: CN
Inventors: 何方; 戴涵文; 林犀; 白茜文
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2022-06-22
Filing date: 2022-06-22
Publication date: 2022-10-04

Abstract

The application provides a traffic control system and method. The system comprises: the overall planning unit is used for planning a motion path for each transport device according to tasks of the plurality of transport devices, generating a motion instruction, sending the motion instruction of each transport device to the transport device, and sending the motion path of each transport device to the cell reservation unit, wherein the path occupied by each transport device when moving on the motion path according to the motion instruction does not conflict, and the overall motion time is shortest; the cell reservation unit is used for reserving the idle cells which do not exceed the maximum reserved number for each transportation device in real time according to the movement path of each transportation device and sending the cell reservation information of each transportation device to the transportation device; and the transportation equipment is used for carrying out movement on the reserved cells according to the movement instruction under the condition that the cells corresponding to the movement instruction are reserved by the transportation equipment according to the cell reservation information.

Description

Traffic control system and method

Technical Field

The present application relates to the field of path planning technologies, and in particular, to a traffic control system and method.

Background

With the rapid development of the e-commerce industry, the increasing amount of orders and parcels poses a serious challenge to the sorting operation of the e-commerce warehouse. In order to solve the problems that the traditional manual mode is low in efficiency, high in cost and the like, the mode that people arrive at goods is changed into the mode that goods arrive at people in the related art, the transportation equipment can move the goods shelf, the goods shelf is sent to a goods picker, the picking efficiency is obviously improved, and the manual operation cost is reduced.

However, when a plurality of transportation devices move, the paths of the transportation devices may collide, and even a "deadlock" phenomenon of the paths occurs, so that each transportation device cannot find a moving path, manual intervention is required to unlock the transportation device, the transportation efficiency of the transportation device is affected, and the labor cost is increased. Therefore, path planning of the transport equipment is one of the key cores of the picking system.

In the related technology, the path planning of the transportation equipment is carried out by using models such as a full coupling model, a decoupling model and a dynamic coupling model, or algorithms such as a search algorithm and a reinforcement learning algorithm. However, these models and algorithms still exist: deadlock and path conflict cannot be avoided, and the resolution mechanism of emergency deadlock and conflict is relied on, so that the efficiency and the robustness are low; when large-scale complex scenes are faced, the solving time is long, and the optimality of the solution cannot be guaranteed. Therefore, how to reasonably plan the path for the transportation equipment is a technical problem which needs to be solved urgently.

Disclosure of Invention

In view of the above, embodiments of the present invention provide a traffic control system and method to overcome or at least partially solve the above problems.

An embodiment of the present invention provides a traffic control system, including:

the overall planning unit is used for planning a motion path for each transport device according to tasks of a plurality of transport devices, generating a motion instruction, sending the motion instruction of each transport device to the transport device, and sending the motion path of each transport device to the cell reservation unit, wherein paths occupied by each transport device when moving on the motion path according to the motion instruction do not conflict, and the overall motion time is shortest;

the cell reservation unit is used for reserving an idle cell which does not exceed the maximum reserved number for each transportation device in real time according to the movement path of each transportation device and sending the cell reservation information of each transportation device to the transportation device;

and the transportation equipment is used for carrying out movement on the reserved cells according to the movement instruction under the condition that the cells corresponding to the movement instruction are determined to be reserved by the transportation equipment according to the cell reservation information.

Optionally, the overall planning unit is further configured to:

and according to the task of the target transportation equipment, synthesizing the motion paths of the plurality of transportation equipment with the planned motion paths, planning the motion paths for the target transportation equipment and generating motion instructions, wherein when the target transportation equipment and the plurality of transportation equipment move on the respective motion paths according to the respective motion instructions, the occupied paths do not conflict, and the total motion time is shortest.

Optionally, the planning of the motion path for each of the transportation devices by the overall planning unit includes: planning a motion path in each time period for each transportation device;

the system further comprises:

and the path information processing unit is used for sending the space-time occupation condition of each path at the starting time of each time period to the overall planning unit, and receiving the motion path which is sent by the overall planning unit and is planned for each transportation device in each time period so as to update the space-time occupation condition of each path in each time period.

Optionally, the transport apparatus is further configured to: and stopping the movement under the condition that the cell corresponding to the movement instruction is determined not to be reserved by the current transportation equipment according to the cell reservation information.

Optionally, the overall planning unit plans a motion path for each transportation device and generates a motion instruction according to the tasks of the transportation devices, including:

determining the priority of each transport device according to the tasks of the transport devices, planning a motion path for each transport device according to the priority of each transport device, and generating a motion instruction, wherein the path occupied by each transport device when moving on the motion path according to the motion instruction is free from conflict, and the total motion time is shortest under the condition of ensuring the priority.

Optionally, the system further comprises:

the candidate path determining unit is used for determining a plurality of candidate paths for the transportation equipment according to the tasks of the transportation equipment and determining the space-time occupation condition of each candidate path to each path in each time period;

the overall planning unit planning a motion path for each transportation device and generating a motion instruction comprises:

and determining a target motion path from the multiple candidate paths of each transport device and generating the motion command according to the multiple candidate paths of each transport device and the space-time occupation condition of each candidate path to each path in each time period, wherein the paths occupied by each transport device when moving on the respective target motion path according to the motion command do not conflict, and the total motion time is shortest.

Optionally, the determining, by the candidate path determining unit, a space-time occupation situation of each path in each time period by each candidate path includes:

for each of the candidate paths within the each time period:

determining a path which is moved by the transportation equipment in the time period according to the candidate path and a path which is influenced by the transportation equipment when the transportation equipment moves in the time period as a path which is occupied by the candidate path in the time period, wherein the path which is influenced by one transportation equipment in one time period is as follows: during the time period, other transportation equipment has the possibility of collision with the transportation equipment when moving on the path;

and obtaining the space-time occupation condition of each candidate path to each channel in each time period according to the channel occupied by each candidate path in each time period.

Optionally, the system further comprises:

the cell type determining unit is used for dividing a target area into a plurality of areas occupied by cells, determining the type of each unit, and sending the area and the type occupied by each cell to the overall planning unit so that the overall planning unit plans a path according to the area and the type occupied by each cell, wherein the types of the units comprise: the system comprises a workstation cell, a workstation queuing cell, a storage area cell, a trunk road cell, a shelf area access cell and a charging cell;

and the passage specifying unit is used for determining the length and the width of each passage according to the size, the safety distance and the kinematic parameters of the transportation equipment.

Optionally, the passage includes a trunk passage and a shelf area passage, and the shelf area passage is a passage below the storage area;

the planning of the motion path for the plurality of transport devices by the general planning unit includes: planning a movement path for the transport equipment that is empty, including or excluding the shelf area access, and planning a movement path for the transport equipment that is loaded, excluding the shelf area access.

Optionally, the trunk road is a one-way traveling road.

The embodiment of the invention also provides a traffic control method, which comprises the following steps:

planning a motion path for each transport device according to tasks of a plurality of transport devices, generating a motion instruction, and sending the motion instruction of each transport device to the transport device, wherein paths occupied by each transport device when moving on the motion path according to the motion instruction do not conflict, and the total motion time is shortest;

and reserving an idle cell not exceeding a maximum reserved number for each transportation device in real time according to the movement path of each transportation device, and sending cell reservation information of each transportation device to the transportation device, so that each transportation device moves on the reserved cell according to the movement instruction under the condition that the cell corresponding to the movement instruction of the transportation device is determined to be reserved by the transportation device according to the cell reservation information.

Optionally, the method further comprises:

Optionally, the planning a motion path for each of the transportation devices includes:

planning a motion path in each time period for each transportation device;

the method further comprises the following steps:

and at the starting time of each time period, acquiring the space-time occupation condition of each passage at the starting time, and acquiring the motion path planned for each transport device in each time period to update the space-time occupation condition of each passage in each time period.

Optionally, after the sending the cell reservation information of each transportation device to the transportation device, the method further includes:

and stopping the movement of each transportation device under the condition that the unit cell corresponding to the movement instruction is determined not to be reserved by the transportation device according to the unit cell reservation information.

Optionally, the planning a motion path for each transportation device and generating a motion instruction according to the tasks of the plurality of transportation devices includes:

and determining the priority of each transport device according to the tasks of the plurality of transport devices, planning a motion path for each transport device according to the priority of each transport device, and generating a motion instruction, wherein the path occupied by each transport device when moving on the motion path according to the motion instruction does not conflict, and the total motion time is shortest under the condition of ensuring the priority.

Optionally, the method further comprises:

determining a plurality of candidate paths for the transportation equipment respectively according to the tasks of the transportation equipment, and determining the space-time occupation condition of each path in each time period by each candidate path;

planning a motion path for each transport device and generating a motion instruction, including:

Optionally, the determining the space-time occupation condition of each candidate path for each path in each time period includes:

for each of the candidate paths within the each time period:

determining a path which the transportation equipment moves in the time period according to the candidate path and a path which is influenced by the transportation equipment when the transportation equipment moves in the time period as a path which is occupied by the candidate path in the time period, wherein the path which is influenced by one transportation equipment in one time period is as follows: during the time period, other transportation equipment has the possibility of collision with the transportation equipment when moving on the path;

Optionally, the method further comprises:

dividing a target area into a plurality of areas occupied by cells, and determining the type of each unit, so as to plan a path according to the areas and types occupied by the cells, wherein the types of the unit comprise: the system comprises a workstation cell, a workstation queuing cell, a storage area cell, a trunk road cell, a shelf area access cell and a charging cell;

the length and width of each passage is determined according to the dimensions, safety distances and kinematic parameters of the transport device.

the planning of the motion path for the plurality of transport devices comprises:

planning a movement path for the transport equipment that is empty, with or without the shelf area access, and planning a movement path for the transport equipment that is loaded, without the shelf area access.

Optionally, the trunk road is a one-way driving road.

The embodiment of the invention has the following advantages:

in the embodiment, the overall planning unit can plan a motion path which does not conflict with each other for each transportation device according to the tasks of the transportation devices, thereby avoiding deadlock and path conflict and improving efficiency and robustness; the cell reservation unit reserves an idle cell for the transportation equipment according to the movement path of the transportation equipment, and the transportation equipment moves on the reserved cell according to the movement instruction under the condition that the transportation equipment confirms that the cell corresponding to the movement instruction is reserved by the transportation equipment, so that collision of the transportation equipment is avoided from one side of the transportation equipment, and the robustness is effectively improved; each transport device moves on the planned movement path according to the movement instruction generated by the overall planning unit, so that the overall movement time can be guaranteed to be shortest, and the optimality of the planned movement path and the generated movement instruction is guaranteed.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the description of the embodiments of the present application will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without inventive exercise.

FIG. 1 is a schematic diagram of a traffic control system according to an embodiment of the present invention;

FIG. 2 is a schematic illustration of a warehouse floor plan and different types of cells in an embodiment of the invention;

FIG. 3 is a schematic view of the direction of motion on a main road in an embodiment of the present invention;

FIG. 4 is a schematic view of the movement of the transportation device along the trunk in an embodiment of the present application;

FIG. 5 is a schematic diagram of the internal path of a memory region in an embodiment of the invention;

FIG. 6 is a schematic illustration of an empty transport equipment through a different pathway in an embodiment of the present invention;

FIG. 7 is a schematic illustration of queuing at a workstation in an embodiment of the present invention;

FIG. 8 is a schematic diagram of a spatiotemporal network in an embodiment of the present invention;

FIG. 9 is a schematic diagram of an occupation of a path according to an embodiment of the present invention;

FIG. 10 is a schematic diagram of the occupation of a path in an embodiment of the present invention;

FIG. 11 is a flow chart illustrating steps of a traffic control method according to an embodiment of the present invention.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, the present application is described in further detail with reference to the accompanying drawings and the detailed description.

Referring to fig. 1, a schematic diagram of an architecture of a traffic control system according to an embodiment of the present invention is shown, and as shown in fig. 1, the traffic control system includes: the system comprises a general planning unit, a cell reservation unit and transportation equipment; the overall planning unit is used for planning a motion path for each transport device according to tasks of a plurality of transport devices, generating a motion instruction, sending the motion instruction of each transport device to the transport device, and sending the motion path of each transport device to the cell reservation unit, wherein paths occupied by each transport device when moving on the motion path according to the motion instruction do not conflict, and the overall motion time is shortest; the cell reservation unit is used for reserving an idle cell which does not exceed the maximum reserved number for each transportation device in real time according to the movement path of each transportation device and sending the cell reservation information of each transportation device to the transportation device; and the transportation equipment is used for carrying out movement on the reserved cells according to the movement instruction under the condition that the cells corresponding to the movement instruction are determined to be reserved by the transportation equipment according to the cell reservation information.

The traffic control system in this embodiment is applied to an intelligent warehouse, and a general planning unit of the traffic control system plans a movement path for each transportation device and sends the movement path to a cell reservation unit, and the cell reservation unit reserves a cell for the transportation device according to the planned movement path, and the transportation device can only move on the reserved cell.

In the intelligent warehouse, including goods storage area, workstation, route, charging area etc. transportation equipment carries out the motion in intelligent warehouse to accomplish various tasks. The goods storage area can be a goods shelf, and the goods can pass through the goods storage area; the workstation is an area for sorting goods; the access can be divided into a trunk access and a shelf area access, the shelf area access is an access below the goods storage area, and the trunk access is other accesses except the shelf area access; each transport device may be an AGV (Automated Guided Vehicle), an AMR (Autonomous Mobile Robot), or another device having a transport function. The transportation equipment moves on a passage in the warehouse, when receiving a task of carrying the goods shelf, the goods shelf is carried from the goods storage area to the workstation, and after the workstation waits for the goods on the goods shelf to be sorted, the goods shelf is carried back to the goods storage area; when a charging task is received, the user moves from the current area (usually a cargo storage area) to the charging area for charging.

Alternatively, to facilitate differentiation by the traffic control system, the traffic control system may include a cell type determination unit. The cell type determining unit is used for dividing the target area into square cells with equal size, wherein the target area can be an area where the warehouse is located. The cell type determining unit further needs to determine the type of each cell according to the real use of the warehouse area represented by each cell. The cell types mainly include: the system comprises a workstation cell, a workstation queuing cell, a storage area cell, a trunk road cell, a shelf area access cell and a charging cell.

Fig. 2 shows a schematic diagram of a warehouse floor plan and different types of cells, where the storage area cells are shelf placement cells and the charging cells are AGV parking cells. The AGVs may need to queue cells at the workstation for the completion of the sorting of the goods at the workstation. Wherein, the unit check that the unit check below and goods shelves put the unit check and enclose all belong to goods shelves district access unit check are put to goods shelves. The main states of the transportation equipment are empty and loaded, and the transportation equipment with empty capacity can pass under the goods shelf, but the transportation equipment with loaded capacity cannot pass under other goods shelves due to the limitation of collision volume of the goods shelves loaded on the transportation equipment. Therefore, when planning a movement path for the transportation equipment, the overall planning unit needs to judge whether the state of the transportation equipment is empty or loaded, and may encourage the planning of a movement path including a shelf area passage for the empty transportation equipment, or certainly plan a movement path not including a shelf area passage; however, when planning a movement path for a loaded transport device, only movement paths which do not include a shelf area access can be planned.

The traffic control system further comprises a passage specifying unit for determining in advance the length and width of each passage based on the size, safety distance and kinematic parameters of the transportation device, and further determining the time taken for the transportation device to travel on each passage. The kinematic parameters of the transport device include speed, acceleration, deceleration, parameters of turning, etc. The safety distance of the transportation equipment is the minimum spacing distance which needs to be kept between the transportation equipment in order to ensure the safety of the transportation equipment. In order to ensure that the transportation device can smoothly pass through the passage, the width of the passage needs to be set according to the size of the transportation device. In order to ensure safety between the transport devices, the minimum length of the passage is set according to the safety distance and kinematic parameters of the transport devices. The length of the trunk road is specified to be L unit cells, and L is more than or equal to N _res +1, wherein, N _res Reserving a cell for the maximum number of cells that can be reserved for one transportation device at a time. L in fig. 2 equals 6.

Optionally, the trunk road is a one-way driving road. In the practical application process, the main road is a one-way running passage, so that the overall working efficiency of each transport device can be improved. The main road comprises a transverse road and a longitudinal road, intersection cells of different roads are defined as intersection cells, and the transportation equipment can continue to run along the original road direction after reaching the intersection cells or turn to the original road after stopping on site to run along the orthogonal direction of the original road. Definition set

Representing all of the trunk paths. The main road divides the whole warehouse plane into a plurality of independent areas, and the size of each area is (L-2) ² And (4) a unit cell. The design of the main road path is designed to keep the reserved number of the unit cells on the transportation equipment along the moving direction to be N all the time _res And then move at the maximum speed, avoiding the occurrence of deceleration due to the reduction of the number of the predicted cells.

When the overall planning unit carries out path planning, the transportation equipment is transportedThe acceleration is considered to be large enough to reach the maximum velocity v of the movement instantaneously _max The acceleration process is negligible. The turning of the transportation equipment can be realized only by pivot turning after the transportation equipment is static, only the accurate turning of 90 degrees and 180 degrees is considered, and the turning time is t _turn (90 deg.) and t _turn (180 °). For the consideration of system safety, in order to simulate the deceleration process of the transportation equipment, the average moving speed of the transportation equipment between two adjacent cells and the required time t (n) are specified to depend on the reserved cell number n of the transportation equipment along the current moving direction; a predetermined number of N _res When the moving speed reaches the maximum, the moving time is t (N) _res ). Table 1 provides an example of where N is listed _res And =4, the time required for the transport device to move one cell varies with the number of reserved cells.

TABLE 1 time required for a transportation device to move a cell as a function of the number of reserved cells

As can be seen from table 1, if the number of reserved cells of the transportation device is 4, the time required for the transportation device to pass through the first cell is 1s, and the number of reserved cells of the transportation device remains 3 after passing through the first cell, so the time required for the transportation device to pass through the second cell is 2s, and so on, the time required for the transportation device to move from the first cell to the fourth cell is 6s. In practical applications, in order to ensure that the transportation device can move at full speed, the cell reservation unit needs to reserve the free cells for the transportation device in real time.

Optionally, all the paths on the main path are specified to be single-row paths, fig. 3 shows a schematic diagram of the moving direction on the main path, and the direction indicated by a white arrow in the diagram is the moving direction on the main path. For any trunk road, if the transportation device does not turn after the road, the time required for movement is Lt (N) _res ) (ii) a If it is usedIf it is necessary to stop the pivot steering after the passage, the time required for the movement is

The transport equipment may effect movement between any two of the cells of the trunk along a single row of lanes, and fig. 4 shows a schematic view of the transport equipment moving along the trunk, where the gray arrows connect, i.e., the direction of transport equipment movement.

In each storage area, the goods shelf is only placed in the cells of one circle of the periphery, and the total number of the cells of the storage area is 4L-12; this placement will facilitate the transport equipment to take away and replace the shelves, avoiding the shelves from stacking. Defining the center of the shelf area (L-4) ² Each cell is a cross-path cell. Definition desk

Representing all shelf area access in the network. Fig. 5 shows a schematic view of the internal passage of a storage area, the transport equipment movement passages of the storage area being of two types: a shelf area internal movement path (short double arrow) and an adjacent shelf area travel path (long double arrow), wherein portions of the shelf symbols are not shown for clarity.

The internal moving passage is limited in adjacent shelf placing cells in the area, the length of the passage is 2 cells, and the time required by the movement of the transportation equipment is t (2); the storage area traversing passage is connected with two adjacent storage areas, starts from the shelf placing unit lattice of one storage area, traverses the corresponding trunk passage through the cross passage unit lattice of the shelf area and reaches the corresponding shelf placing unit lattice of the adjacent storage area. The design purpose of the passing path is to provide more flexible paths for the movement of the no-load transportation equipment, share the traffic flow of the main path and improve the passing efficiency of the network. The length of the shelf passing path is L unit cells, and is the same as that of the trunk path. Likewise, if the transport equipment does not turn after the passage, the time required for movement is Lt (N) _res ) (ii) a If it is desired to stop pivot steering after the pass, the time required for movement is

Fig. 6 shows a schematic diagram of the passage of the empty transport device through different paths, wherein, comparing the movement trajectories of the empty transport device between two shelving units through the trunk path (dotted arrow) and through the shelf area path (solid arrow), respectively, it can be seen that the movement of the empty transport device through the shelf area path is more flexible, using less trunk path resources.

In each workstation area, a workstation cell and a plurality of workstation queuing cells for connecting the trunk and the workstations are required to be arranged. Definition set

Representing all the station area paths in the network. The movement paths of the transport devices in the workstation area are of only one type: queuing the moving path. The queuing movement path is limited to queuing cells of adjacent workstations in the area, the path length is 2 cells, and the time required for the transportation equipment to move is t (2). As shown in the schematic diagram of queuing at a workstation in fig. 7, the dashed short arrows represent queued movement paths within the area, and the solid long arrows represent previously defined trunk paths; the transportation equipment carrying the target goods shelf stops steering at the corresponding trunk passage cell, advances along the queuing moving passage, reaches the front of the working station cell, stops waiting for completion of goods shelf picking work, leaves the working station area along the subsequent queuing moving passage, enters the corresponding cell of the trunk passage, stops steering and then moves along the trunk passage.

Defining all the paths of the warehouse area, and then, defining the time period length T = Lt (N) of the system operation _res ) I.e. the time required for the transport equipment of the main road to move through a section of the main road without turning. Through the defined time period length, the continuous time is discretized, and the original physical space network is upscaled into a space-time network, as shown in fig. 8. The initial movement time of the transport equipment in each passage is

At the start cell of the passage, the transport device can only start moving along the passage if the system time reaches the start time of the passage.

All the paths are specified to only accommodate one piece of transportation equipment in one time period, and the path information processing unit records and updates the occupation condition of each path in each time period, so that the occupation of the transportation equipment on the paths is ensured not to conflict. The transport equipment travelling along a route during a cycle will not only occupy the capacity of the current route during that cycle, but will also occupy the surrounding affected routes. Fig. 9 shows an occupation situation of a passage, and in the current time period, the transportation device moves along the one-way passage (10, 5) → (5, 5) (no turning after the end), it will occupy not only the one-way passage (10, 5) → (5, 5), but also the target intersection orthogonal direction one-way passage (5, 0) → (5, 5), wherein the one-way passage (10, 5) → (5, 5) is a passage through which the transportation device moves in the time period, and the one-way passage (5, 0) → (5, 5) is a passage affected when the transportation device moves in the time period. Fig. 10 shows an occupation of a pathway, and in the current time period the transport device moves along the pathway (9, 7) → (4, 7) (without turning after the end), it will occupy not only the capacity of the pathway (9, 7) → (4, 7) at that period, but also the capacity of the relevant affected pathway (indicated by a dashed line) at that time period, and traverse the relevant affected pathway (indicated by a solid line) at that period. If the paths occupied by two transportation devices overlap during the same time period, the two transportation devices may collide.

The movement path of the transportation equipment in the passage is planned by the overall planning unit. The overall planning unit plans a respective motion path for each transport device and generates a respective motion instruction for each transport device according to the tasks of the plurality of transport devices. The movement instructions of the transportation equipment comprise instructions of moving, carrying, waiting in place, lifting a shelf, putting down the shelf and the like. The motion instructions of each transport device instruct the transport device to move on the motion path of the transport device and complete the corresponding action. The paths occupied by each transport device when moving on the own motion path according to the own motion instruction do not conflict, and the total motion time is shortest.

And the overall planning unit sends the motion path and the motion instruction of each transport device to the information processing unit of the transport device, so that the information processing unit of each transport device sends the motion instruction to the motion control unit of the transport device to control the transport device to complete the corresponding motion instruction.

The transportation equipment moves in the warehouse, and the corresponding cell needs to be reserved. Each transport device can only reserve at most no more than the maximum number of spare cells (including the cells in which it is located) at a time. In order to prevent conflict among the transportation devices, each cell can only be reserved for one transportation device at most at the same time, and after the transportation device passes through the cell, the reserved cell can be released to receive reservation applications of other transportation devices.

In order to reserve the idle cells for each transportation device according to the movement path of each transportation device, the overall planning unit sends the movement path of each transportation device to the cell reservation unit, the cell reservation unit reserves the idle cells not exceeding the maximum number of reservations for each transportation device in real time according to the movement path of each transportation device, and sends the cell reservation information of each transportation device to the information processing unit of the transportation device.

And the information processing unit of each transport device judges whether the cell corresponding to the motion instruction of the current transport device is reserved by the current transport device or not according to the received cell reservation information corresponding to the current transport device. And under the condition that the cell corresponding to the motion instruction of the current transportation equipment is reserved by the current transportation equipment, the motion instruction is sent to the motion control unit of the current transportation equipment, and the motion control unit of the transportation equipment of the current transportation equipment moves on the reserved cell according to the motion instruction. And under the condition that the cell corresponding to the motion instruction of the current transportation equipment is not reserved by the current transportation equipment, the current error is proved to occur, so that the information processing unit of the current transportation equipment sends a motion stopping instruction to the motion control unit of the current transportation equipment, and the motion control unit of the current transportation equipment stops moving according to the motion stopping instruction.

Optionally, the path planned by the overall planning unit for each transport device is a path which is discretized into each time period, but the transport device is continuously moved during the actual movement. In order to prevent the transportation devices from transmitting collisions, the start times of the movement paths planned by the overall planning unit for the transportation devices may be different. For example, it may be that a part of the transportation devices may start to move according to the planned movement path in the current time period, and that a part of the transportation devices may need to start to move according to the planned movement path in the next time period.

The overall planning unit can plan the motion path for each current transportation device at one time according to the task of each current transportation device. However, part of the target transportation devices may complete previous tasks, or may be in an idle state without receiving tasks before, when the target transportation devices receive the tasks, for overall efficiency, it is not possible to wait for all previous transportation devices with planned movement paths to complete the tasks before planning the paths for the target transportation devices, and the movement paths for the target transportation devices should be planned and the movement instructions of the target transportation devices should be generated on the basis of considering the movement paths of the multiple transportation devices with the planned movement paths. When the target transportation equipment moves on the own movement path according to the own instruction, the target transportation equipment does not conflict with other transportation equipment, and the total movement time of the target transportation equipment and the plurality of transportation equipment with the planned movement path is shortest.

Optionally, the traffic control system further includes a path information processing unit, where the path information processing unit communicates with the general planning unit at the start time of each time period, feeds back the space-time occupancy of each current path to the general planning unit, and then records and updates the space-time occupancy of each path according to the path planning information of each transportation device returned by the general planning unit.

Optionally, when the overall planning unit plans the motion path for each transportation device according to the task of each transportation device and generates the motion instruction, the overall planning unit may determine the priority of each transportation device according to the task of each transportation device, plan the motion path with the priority information for each transportation device and generate the corresponding motion instruction, so that when each transportation device moves on the motion path according to the motion instruction, the occupied paths do not conflict. Wherein the transport equipment performing the emergency task may have a higher priority.

Optionally, when planning the motion path, the overall planning unit may select one of the candidate paths of each transportation device as the motion path of the transportation device. Wherein the candidate route of the transportation device may be predetermined by the candidate route determination unit.

The moving path of the transportation equipment is composed of continuous end-to-end passages, and the initial moving time of each passage is

According to the movement starting point and the specific task of the transportation equipment, a plurality of alternative execution schemes are specified for the transportation equipment in advance. For example, when the task is a transporting rack task, it is considered that the transporting apparatus single rack transporting task only serves one workstation, and therefore, a complete rack transporting task execution scheme includes: a task execution path r consisting of three sub-paths in segments, denoted by r = (r) ₁ ，r ₂ ，r ₃ ) Represents; and three-segment stop waiting in the task execution process, and waiting by d = (d) ₀ ，d ₁ ，d ₂ ) And (4) showing. The symbols are explained as follows: initial dwell wait time d ₀ Representing the beginning of the transport apparatus along the sub-path r ₁ Before moving, the transportation equipment stays at the starting point unit cell for the waiting time period number; sub-path r ₁ The starting point is a shelf placing unit lattice (or a transportation equipment parking unit lattice), the end point is another shelf placing unit lattice, the state of the transportation equipment is no-load, and the corresponding task stage is that the shelf is lifted up below the appointed shelf; dwell wait time d ₁ Is represented on the sub-path r ₁ After finishing, the transport device starts following the sub-path r ₂ Before moving, the transport equipment is in the sub-path r ₁ The number of end point cell dwell wait cycles; sub-path r ₂ The starting point is a shelf placing unit lattice, and the end point isQueuing unit cells in front of the working station unit cells, wherein the transport equipment is in a load state, and the corresponding task stage is to transport the appointed goods shelf to the working station to finish picking; dwell wait time d ₂ Is represented on the sub-path r ₂ After finishing, the transport device starts following the sub-path r ₃ Before moving, the transport equipment is in the sub-path r ₂ The end point cell of (1) stays for the number of wait cycles, wait time d ₂ The picking time of the goods shelf on the workbench is not less than the required picking time; sub-path r ₃ The starting point is a queuing unit cell in front of the workstation unit cell, the end point is a shelf placing unit cell, the state is a load, and the corresponding task is returning the shelf which is sorted.

Generating each sub-path r in advance by a K-shortest path algorithm (K-short path algorithm) according to the starting point and the end point of the path _m K shortest paths, m e {1,2,3}. For sub-path r ₁ The transport equipment is in an empty state and encourages the transport equipment to pass through the shelf area to reduce traffic pressure on the main road, and the set of the paths is

For sub-path r ₂ And r ₃ The transport equipment state is load, can not pass through the shelf area, only the trunk path can be used when K shortest paths are defined and generated, and the set corresponding to the paths is

And

the three sub-paths are mutually combined, and the transportation equipment v and the task w have K ³ A different task execution path is provided

Wherein

Defining a feasible set of initial dwell latency periods as

Number of stay waiting cycles d ₁ Is a feasible set of

Wherein

The minimum number of cycles required to raise the pallet and turn; number of stay waiting cycles d ₂ Is a feasible set of

Wherein

A minimum number of cycles to complete shelf picking for the picking station; then there is

Wherein

For scheme (r, d), variables are defined

And variables of

The values of these variables will be calibrated in advance as the pallet handling task performance scenario (r, d) is generated. Wherein for the path r the transport device can only move along a predetermined path, the speed and movement of which pathThe time is a fixed value, and meanwhile, the stay waiting time is specified to be integral multiple of the period; so the total moving time of the scheme (r, d) is also a fixed value, defined as c _r，d 。

If the empty transportation device is not assigned a rack handling task, or is out of charge, it needs to return to the transportation device parking (charging) cell e (the parking cell is designated in advance). Several alternative movement schemes will be prescribed in advance for the transport device depending on its start and end of movement cell locations. A complete empty transport equipment movement scheme comprises: a moving path r 'and an initial stop wait d'. The symbols are specifically explained as follows: the initial dwell wait time d 'represents the number of dwell wait cycles for the transport device at the starting cell before the transport device begins to move along the path r'; the starting point of the path r' is a shelf placing unit cell, the end point is a designated transportation equipment parking unit cell, and the state of the transportation equipment is no-load.

And generating K shortest paths of the path r' in advance by the K shortest path algorithm according to the starting point and the end point of the path. For the path r', the transport equipment is empty, and is encouraged to pass through the shelf area to reduce traffic pressure on the trunk, and the set of the paths corresponds to

Defining a feasible set of initial dwell latency periods as

For the scheme (r ', d'), variables are defined

And variables

The values of these variables will be calibrated in advance as the pallet handling task performance scenario (r ', d') is generated. The total moving time of the scheme (r ', d') is also a fixed value, defined as c _r′，d′ 。

At each time period, the idle transport receives a new task, creating a motion demand. The overall planning unit will unify the planning schemes for the transportation devices for the motion demands of the transportation devices accumulated in the period through the solution of the following integer planning problem, minimize the overall moving time, and ensure no collision between the motion paths of different transportation devices:

wherein, the variable is 0 to 1

Indicating whether or not the transport apparatus v performing the rack carrying task adopts the plan (r, d); similarly, the variables 0-1

Indicating whether the transport device v empty to the parking place adopts the scheme (r ', d'). Wherein E ^a，τ Represents the residual capacity of the path a at the period tau, and is 0 or 1; and M represents a sufficiently large number. v denotes a set of transport devices performing a pallet handling task, and v' denotes a set of transport devices traveling empty to a parking lot. The objective function (1) is to minimize the overall moving time of each transport device; constraints (2) and (3) limit each transport device to select only one movement plan; constraint (4) ensures that the space-time occupation of the access corresponding to the scheme selected by the transport equipment does not exceed the residual capacity of the access, thereby avoiding the conflict between the transport equipment; restricting (5) passage passing corresponding to a scheme selected by the transportation equipment, allowing a passage to be passed for multiple times in one period, wherein the passage cannot be passed once being occupied, and the passage cannot be occupied once being passed; the remaining symbols and letters may be referred to as described above.

In order to reflect the priority of each transportation device in the solution of the integer programming problem, a weight coefficient may be added to the candidate path of each transportation device.

The method aims at an intelligent picking system, and provides a brand-new traffic control scheme, namely a traffic control scheme based on space-time access, for the multi-agent path planning problem in the intelligent picking system based on a cell network and reservation control. Defining a main road passage according to a kinematic model of the transportation equipment, and mainly dividing a warehouse plane into a sorting workstation area and a goods shelf area; a shelf area access is defined to fully exploit the flexible passing characteristics of empty transport equipment under the shelf. And defining the system operation period, and upgrading and maintaining the path of the physical network into a space-time path, wherein each path allows at most one transport device to pass through in each period. Based on the space-time pathway, several alternative execution schemes are prescribed for the transportation device in advance according to the movement starting point and the specific shelf carrying task of the transportation device, and the schemes occupy the capacity of the corresponding space-time pathway and cross the space-time pathway. Finally, an integer programming problem is solved through optimization, a scheme is uniformly programmed for the movement demands of the transportation equipment accumulated in one period, the total movement time is minimized, and conflict-free collision among the movement schemes of different transportation equipment is guaranteed.

Referring to fig. 11, a flowchart illustrating steps of a traffic control method according to an embodiment of the present invention is shown, where the traffic control method may be applied to a server, a control platform, an electronic device, and the like. As shown in fig. 11, the traffic control method may specifically include the following steps:

step S11: planning a motion path for each transport device according to tasks of a plurality of transport devices, generating a motion instruction, and sending the motion instruction of each transport device to the transport device, wherein paths occupied by each transport device when moving on the motion path according to the motion instruction do not conflict, and the total motion time is shortest;

step S12: reserving an idle cell which does not exceed the maximum number of reservations for each transportation device in real time according to the movement path of each transportation device, and sending cell reservation information of each transportation device to the transportation device, so that each transportation device moves on the reserved cell according to the movement instruction under the condition that the cell corresponding to the movement instruction of the transportation device is determined to be reserved by the transportation device according to the cell reservation information.

The traffic control method in the embodiment can plan a motion path for each transportation device and generate a motion instruction aiming at traffic control in the intelligent warehouse, and sends the motion instruction of the transportation device to the transportation device; and reserving the idle cells which do not exceed the maximum number of reservations for each transportation device according to the movement path of each transportation device, and then sending the cell reservation information of the transportation device to the transportation device, so that the transportation device moves on the reserved cells according to the movement instruction of the transportation device under the condition that the cells corresponding to the movement instruction of the transportation device are determined to be reserved by the transportation device according to the cell reservation information.

Optionally, if the cell corresponding to the movement instruction of the transportation device is not reserved for the transportation device in the cell reservation information received by the transportation device, it is proved that an error occurs, and the transportation device stops moving in order to avoid causing a larger problem or avoid causing a chain reaction.

Optionally, after the motion paths of the plurality of transportation devices have been planned, specifically, when the plurality of transportation devices have not started to move, or when a part of the transportation devices start to move, or when the plurality of transportation devices have not completed the planned motion, if a task of the target transportation device is received, the motion paths of the plurality of planned transportation devices may be planned for the target transportation device, and the motion instruction may be generated. The target transportation device may be a newly added transportation device, or a transportation device that has completed a previous task among a plurality of transportation devices. When the target transportation device and the plurality of transportation devices move on the respective movement paths according to the respective movement commands, the occupied paths do not conflict, and the total movement time is shortest.

The movement path planned for each transport device and the target transport device refers to the movement path in each time period. Although the transportation devices are in continuous motion in the actual motion process, the continuous motion of the transportation devices can be discretized into the motion path in each time period by dividing the time period, so that whether the transportation devices send conflicts or not is judged by comparing the motion paths of the transportation devices in each time period.

Specifically, at the starting time of each time period, the space-time occupation condition of each path at the starting time is obtained, and the movement path planned for each transportation device in each time period is obtained, so that the space-time occupation condition of each path in each time period is updated.

Optionally, each transport device has a different task and a different priority, e.g., a transport device performing an emergency task may have a higher priority. Therefore, when the motion path is planned for each transport device, the motion path can be planned for each transport device according to the priority of each transport device, and the motion instruction can be generated, so that the paths occupied by each transport device when moving on the motion path according to the motion instruction can not conflict, and the total motion time is shortest under the condition of ensuring the priority.

Optionally, a plurality of candidate paths may be determined for each transportation device respectively according to the task of each transportation device, and the space-time occupation condition of each candidate path on each path in each time period may be determined.

The candidate path of the transport device may be predetermined. According to a plurality of positions required to be reached by the task, a path formed by adjacent position points in the arrival time sequence of one position point is a section of sub-path, K shortest paths of each section of sub-path are generated in advance through a K shortest path algorithm, and a candidate path can be obtained according to the K shortest paths. For example, it is necessary to reach position B from position a first and then reach position C from position B, where there are 2 shortest paths from position a to position B and 3 shortest paths from position B to position C, and then 6 candidate paths can be obtained.

And acquiring the space-time occupation condition of each path in each time period when the transportation equipment advances on the candidate path at full speed.

When a motion path is planned for each transport device and a motion instruction is generated, a target motion path is determined from a plurality of candidate paths of each transport device and the space-time occupation condition of each path of each candidate path in each time period directly according to the plurality of candidate paths of each transport device and the space-time occupation condition of each candidate path to each path in each time period, and the motion instruction is generated, wherein paths occupied by each transport device when moving on the respective target motion path according to the motion instruction do not conflict, and the total motion time is shortest.

Optionally, to avoid collisions, the path taken by the transport device during a time period is not only the path that the transport device has moved during the time period, but also the path that the transport device has affected while moving during the time period. The path that a transport device affects during a time period is: during this time period, there is a possibility that other transport apparatuses collide with the transport apparatuses while moving on the path. According to the path occupied by each candidate path in each time period, the space-time occupation condition of each path in each time period by each candidate path can be obtained.

Optionally, to facilitate the distinction, the target area may be divided into square cells of equal size, wherein the target area may be an area where the warehouse is located. The cell type determining unit further needs to determine the type of each cell according to the real use of the warehouse area represented by each cell. The cell types mainly include: the system comprises a workstation cell, a workstation queuing cell, a storage area cell, a trunk road cell, a shelf area access cell and a charging cell.

The length and width of each passage can be determined according to the size, safety distance and kinematic parameters of the transport equipment. The kinematic parameters of the transport device include speed, acceleration, deceleration, parameters of a turn, etc. The safety distance of the transportation equipment is the minimum spacing distance which needs to be kept between the transportation equipment in order to ensure the safety of the transportation equipment. In order to ensure that the transportation device can smoothly pass through the passage, the width of the passage needs to be set according to the size of the transportation device. In order to ensure safety between the transport devices, the minimum length of the passage is set according to the safety distance and the kinematic parameters of the transport devices.

Optionally, the pathway includes a trunk pathway and a shelf area pathway, the shelf area pathway being a pathway below the storage area. The state of the transportation equipment is divided into no-load and load, the no-load transportation equipment can pass under the goods shelf, but the loaded transportation equipment cannot pass under other goods shelves due to the limitation of collision volume of the goods shelves carried on the loaded transportation equipment. Therefore, when planning a movement path for the transportation equipment, it is necessary to determine whether the state of the transportation equipment is empty or loaded, and it is possible and encouraged to plan a movement path including a shelf area path for the empty transportation equipment, and certainly, it is also possible to plan a movement path not including a shelf area path; however, when planning a movement path for a loaded transport device, only a movement path which does not include a shelf space access can be planned.

Optionally, the trunk road is a one-way driving road. In the practical application process, the main road is a one-way running passage, so that the overall working efficiency of each transport device can be improved. The main road passage comprises a transverse passage and a longitudinal passage, intersection cells of different passages are defined as intersection cells, and the transportation equipment can continue to run along the original passage direction after reaching the intersection cells or turn to the original passage direction after stopping on site.

Optionally, when the motion path is planned for the transportation device, the planned motion path may be obtained by solving an integer planning problem. The integer programming problem may specifically refer to the above.

It can be understood that, for specific steps of the embodiment of the method, reference may be made to the description in the foregoing system embodiment, and details are not described herein again.

It should be noted that for simplicity of description, the method embodiments are shown as a series of combinations of acts, but those skilled in the art will recognize that the embodiments are not limited by the order of acts, as some steps may occur in other orders or concurrently in accordance with the embodiments. Further, those skilled in the art will appreciate that the embodiments described in the specification are presently preferred and that no particular act is required to implement the invention.

The embodiments in the present specification are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

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

Embodiments of the present invention are described with reference to flowchart illustrations and/or block diagrams of methods, apparatus, electronic devices and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing terminal to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing terminal to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing terminal to cause a series of operational steps to be performed on the computer or other programmable terminal to produce a computer implemented process such that the instructions which execute on the computer or other programmable terminal provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While preferred embodiments of the present invention have been described, additional variations and modifications of these embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the embodiments of the invention.

Finally, it should also be noted that, in this document, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrases "comprising one of \ 8230; \8230;" does not exclude the presence of additional like elements in a process, method, article, or terminal device that comprises the element.

The traffic control system and method provided by the present application are described in detail above, and the principle and the implementation of the present application are explained in the present application by applying specific examples, and the description of the above examples is only used to help understanding the method and the core idea of the present application; meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.

Claims

1. A traffic control system, characterized in that the system comprises:

2. The system of claim 1, wherein the population planning unit is further configured to:

3. The system of claim 1, wherein the general planning unit planning the motion path for each of the transport apparatuses comprises: planning a motion path in each time period for each transportation device;

the system further comprises:

4. The system of claim 1, wherein the transport device is further configured to: and stopping the movement under the condition that the cell corresponding to the movement instruction is determined not to be reserved by the current transportation equipment according to the cell reservation information.

5. The system of claim 1, wherein the overall planning unit plans a motion path for each of the transportation devices according to the tasks of the plurality of transportation devices and generates motion instructions, comprising:

6. The system of claim 1, further comprising:

the overall planning unit planning a motion path for each transport device and generating a motion instruction includes:

7. The system of claim 6, wherein the candidate path determination unit determines the space-time occupancy of each of the candidate paths for each of the paths in each time period, comprising:

for each of the candidate paths within the each time period:

8. The system of claim 1, further comprising:

9. The system of claim 8, wherein the pathway comprises a backbone pathway and a shelf area pathway, the shelf area pathway being a pathway below a storage area;

the planning of the motion path for the plurality of transport devices by the general planning unit includes: planning a movement path for the transport equipment that is empty, with or without the shelf area access, and planning a movement path for the transport equipment that is loaded, without the shelf area access.

10. The system of claim 8, wherein the arterial road is a one-way road.

11. A traffic control method, characterized in that the method comprises:

reserving an idle cell which does not exceed the maximum number of reservations for each transportation device in real time according to the movement path of each transportation device, and sending cell reservation information of each transportation device to the transportation device, so that each transportation device moves on the reserved cell according to the movement instruction under the condition that the cell corresponding to the movement instruction of the transportation device is determined to be reserved by the transportation device according to the cell reservation information.