Object detection method and system

Abstract

This object detection method is a method for detecting an object disposed in a plurality of spots (S1-S12) defined within a prescribed detection region (DR), and causes a computer to execute: a step for collecting scan data from one or more mobile bodies (2) that scan the detection region at prescribed time intervals; and a step for detecting, for the plurality of spots (S1-S12) within the detection region (DR), an occupied spot (OS) in which the object is disposed and a vacant spot (FS) in which the object is not disposed, on the basis of the scan data.

Description

Object Detection Method and System 【0001】 The present invention relates to an object detection method and system. 【0002】 For example, a self-driving forklift is deployed in a warehouse for storing goods. When this forklift receives a conveyance instruction from a computer such as a server that manages the warehouse, it conveys a pallet or the like on which goods are placed from, for example, a first location to another second location within the warehouse. 【0003】 The placement locations of pallets and the like at the first location and the second location are determined by, for example, performing image processing on an image from a fixed-point camera fixed to the ceiling or columns of the warehouse. However, with a fixed-point camera, it may not be possible to determine the presence or absence of a pallet in the blind spot of the fixed-point camera behind a certain pallet. 【0004】 The present invention has been made to solve the above problems, and an object of the present invention is to provide an object detection method and system capable of detecting an object with higher accuracy. 【0005】 According to a first aspect of the present invention, there is provided an object detection method which is an object detection method for detecting an object placed at a plurality of spots defined within a predetermined detection area, and causes a computer to collect scan data from one or more moving bodies that scan the detection area at a predetermined time interval, and based on the scan data, detect, for the plurality of spots within the detection area, occupied spots where the object is placed and empty spots where the object is not placed. 【0006】 The occupied spots and the empty spots are updated based on the latest scan data. 【0007】 The object detection method further causes the computer to change the occupied spots and the empty spots to unknown spots where the presence or absence of the object placement is unknown after a predetermined time has elapsed since the detection of the occupied spots and the empty spots. 【0008】The object detection method further causes the computer to perform the step of updating the unknown spot to the occupied spot or the empty spot based on the scan data collected from the one or more moving objects. 【0009】 The scan data is collected while the mobile body is working. 【0010】 The scan data is collected continuously while the moving object is in motion. 【0011】 The object detection method further causes the computer to perform the step of detecting unknown spots where the presence or absence of the object is unknown, based on the scan data. 【0012】 The object detection method further involves instructing the computer to instruct the mobile body to transport the object located at the occupied spot within the detection area. 【0013】 The instruction is to transport the object to another empty spot within the detection area. 【0014】 The object detection method further causes the computer to update the occupied spot and the empty spot based on the scan data collected from the mobile body engaged in transporting the object. 【0015】 The object detection method further involves instructing the computer to transport the object to the mobile body in the empty spot within the detection area. 【0016】 The instruction is an instruction to transport the object from the occupied spot within another detection area. 【0017】 The object detection method further causes the computer to update the occupied spot and the empty spot based on the scan data collected from the mobile body engaged in transporting the object. 【0018】 The aforementioned mobile body is an autonomous mobile body. 【0019】The mobile body is an autonomous forklift capable of autonomous movement, and the object is an article placed on a pallet. 【0020】 The moving object is a manned forklift operated by an operator, and the object is an article placed on a pallet. 【0021】 According to a second aspect of the present invention, an object detection system is provided which is configured to perform the object detection method described in any of the above. 【0022】 According to a second aspect of the present invention, a computer-readable medium is provided that includes an instruction causing a computer to execute the object detection method described in any of the above. 【0023】 This is a schematic perspective view showing a warehouse system 1 according to one specific example. This is a schematic perspective view showing the structure of a forklift 2 according to one specific example. This is a schematic plan view showing the structure of a forklift 2 according to one specific example. This is a schematic functional block diagram showing the control system of the management server 6. This is a schematic functional block diagram showing the control system of the forklift 2. This is a schematic plan view showing the configuration of a temporary storage area 14 according to one specific example. This is a plan view showing a scene in which the forklift 2 collects scan data while in motion. This is a plan view showing a scene in which the forklift 2 collects scan data while in motion. This is a plan view for explaining an example of the work of the forklift 2. 【0024】 1. Overview of the Warehouse System An embodiment of the present invention will be described below with reference to the attached drawings. Figure 1 is a schematic perspective view showing a warehouse system 1 according to one specific example. As shown in Figure 1, an example of the warehouse system 1 has a lower floor 10 and a floor above the lower floor 10, i.e., an upper floor 11. Travel paths for autonomous mobile units 2 are formed on the floor surfaces of the lower floor 10 and the upper floor 11, respectively. The mobile unit 2 is, for example, an autonomous forklift 2 that can autonomously travel on the floor surface of the lower floor 10 and the upper floor 11 by self-position estimation. In this example, multiple forklifts 2 are arranged on the lower floor 10 and the upper floor 11, respectively. 【0025】 In the warehouse system 1, temporary storage areas 14 are defined in predetermined areas of the floor surfaces of the lower floor 10 and upper floor 11 for temporarily storing pallets 13 on which one or more corrugated boxes 12 containing a large number of identical or different items are placed. In this example, the pallets 13 are placed directly on the floor surface. Multiple temporary storage areas 14 may be defined on the floor surface. The pallets 13 are formed in a rectangular or straight, flat plate shape in plan view. A pair of insertion openings for inserting the forks of a forklift 2 are formed on the four sides of the pallet 13 that connect the opposing front and back surfaces. The corrugated boxes 12 and pallets 13 constitute objects according to the present invention. 【0026】 The warehouse system 1 has racks 15 arranged on the floor surfaces of the lower floor 10 and the upper floor 11. The racks 15 are, for example, storage shelves for storing one or more cardboard boxes 12 as described above, placed on pallets 13. These racks 15 are storage shelves for storing the items inside the cardboard boxes 12 on the pallets 13. The racks 15 have a plurality of rack units 15b formed by, for example, metal frame members 15a. These plurality of rack units 15b are stacked in the height direction, and at the same time, adjacent rack units 15b are joined in the width direction and length direction parallel to the floor surface to form the racks 15. 【0027】 Each rack unit 15b defines one storage space 15c for accommodating a pallet 13 on which one or more cardboard boxes 12 are placed. The forks of a forklift 2 can access each storage space 15c from the side of the rack 15. In this way, the forklift 2 can load the pallets 13 into the storage space 15c from the side of the rack 15 and remove the pallets 13 to the outside of the storage space 15c from the side of the rack 15. Note that the number of rack units 15b constituting the rack 15 described above in the height and length directions is just an example, and the rack 15 may be formed by connecting other numbers of rack units 15b to each other. 【0028】The warehouse system 1 has a vertical transport device 16 that can transport pallets 13 carrying one or more cardboard boxes 12, or pallets 13 only, between the lower floor 10 and the upper floor 11. This vertical transport device 16 has a transport mechanism 16a that can move up and down in the vertical transport space, and conveyors 16b that extend to the transport mechanism 16a on the lower floor 10 and the upper floor 11, respectively. The conveyor 16b can transport pallets 13 that have been transported to the conveyor 16b by a forklift 2, for example, to the transport mechanism 16a, and can also transport pallets 13 that have been transported by the transport mechanism 16a to just before the forklift 2. The transport mechanism 16a can transport pallets 13 that have been transported by the conveyor 16b from the lower floor 10 to the upper floor 11, or from the upper floor 11 to the lower floor 10. 【0029】 On the lower floor 10 and upper floor 11, there are human workers (operators) 3, and other mobile devices such as a manned forklift 4 operated by worker 3, and other transport robots 5. Workers 3 perform various tasks on the lower floor 10 and upper floor 11, such as transporting cardboard boxes 12, placing them on pallets 13, and responding to malfunctions of the forklift 2. The manned forklift 4 and other transport robots 5 are mobile devices that are not connected to the management server of the warehouse system 1, which will be described later. The operation of these manned forklifts 4 and transport robots 5 may be controlled by a server owned by an administrator different from the management server of the warehouse system 1, for example. However, the manned forklifts 4 and transport robots 5 may be connected to the management server described later. 【0030】In a plan view of the floor surfaces of the lower floor 10 and the upper floor 11, the areas other than the area where the temporary storage area 14 is defined and the area where the racks 15 are placed are defined as movement paths for forklifts 2, manned forklifts 4, and other transport robots 5. The predetermined areas around the temporary storage area 14 and the predetermined areas around the racks 15 are defined as buffer areas where entry by forklifts 2 and manned forklifts 4 is restricted. However, when forklifts 2 or manned forklifts 4 enter the temporary storage area 14 or when forklifts 2 or manned forklifts 4 load or unload pallets 13 onto the racks 15, these buffer areas are temporarily released. Furthermore, human workers 3 can move freely on the upper floor 11 or the floors of the upper floor 11 without being restricted by these buffer areas. 【0031】 2. Diagram 2 of the forklift configuration is a perspective view that schematically shows the structure of a forklift 2 according to one specific example. The forklift 2 is used to transport cardboard boxes 12 (i.e., goods) placed on pallets 13 to various locations within the warehouse system 1. The forklift 2 can also transport only cardboard boxes 12 that are not placed on pallets 13. As mentioned above, the forklift 2 can, in principle, autonomously drive based on self-position estimation within the warehouse system 1. However, the forklift 2 can also be driven manually by a human worker 3, similar to a manned forklift 4. 【0032】 In the following explanation, in the longitudinal direction of the forklift 2, the direction toward the front of the forklift 2 is defined as the forward direction FD, while the direction toward the rear of the forklift 2, opposite to the forward direction FD, is defined as the rear direction BD. Similarly, in the height direction of the forklift 2, the direction toward the top of the forklift 2 is defined as the upward direction UD, while the direction toward the bottom of the forklift 2, opposite to the upward direction UD, is defined as the downward direction DD. Furthermore, in the left-right direction of the forklift 2, the direction toward the left of the forklift 2 is defined as the left direction LD, while the direction toward the right of the forklift 2, opposite to the left direction LD, is defined as the right direction RD. 【0033】 The forklift 2 has a body 20 and a cargo handling assembly 21 located at the front end of the body 20. The body 20 has a main body 20a, a pair of straddle legs 20b, 20b extending parallel to each other in the forward direction FD from the front end of the main body 20a, and a head guard 20c attached to the upper end of the main body 20a. The main body 20a has, for example, a driver's seat 20d at its rear end where an operator 3 can stand, and an operating unit 20e on its upper surface for the operator 3 to operate the forklift 2. The cargo handling assembly 21 is located between the straddle legs 20b, 20b. The head guard 20c prevents loads or objects from falling onto the operator from above. 【0034】 The vehicle body 20 includes a pair of front wheels 22 positioned under each of the straddle legs 20b, and, for example, one rear wheel (not shown) positioned under the main body 20a. A drive motor (not shown), for example, built into the main body 20a, is connected to the rear wheel. Power is supplied to the drive motor from, for example, a battery (not shown), similarly built into the main body 20a. That is, the rear wheel is the drive wheel, while the front wheel 22 is the driven wheel. By driving the rear wheel in the direction of travel and changing its angle in the left-right direction, the forklift 2 can move forward, backward, left-right, and right. When transporting the pallet 13, the forklift 2 travels in the rear direction BD. 【0035】 The cargo handling assembly 21 is an assembly capable of lifting and lowering pallets 13. The cargo handling assembly 21 includes a mast assembly 23 and a fork assembly 24. The mast assembly 23 is supported between a pair of straddle legs 20b, 20b so as to be movable in the forward direction FD and the rearward direction BD. The fork assembly 24 is supported at the front end of the mast assembly 23 so as to be movable in the upward direction UD and the downward direction DD. In the state shown in Figure 2, the mast assembly 23 is positioned at its maximum forward position in the forward direction FD. The fork assembly 24 is positioned at a position raised upward in the upward direction UD from its lowest position. 【0036】The mast assembly 23 includes a base 23a positioned between a pair of straddle legs 20b, 20b, a pair of outer masts 23b, 23b that rise upright from the base 23a in the direction UD, and a pair of inner masts 23c, 23c positioned inside the leftward LD and rightward RD directions of the pair of outer masts 23b, 23b, respectively. The outer masts 23b, 23b are integrally formed, for example, at the front end of the base 23a. The outer masts 23b, 23b are spaced apart from each other at a predetermined interval in the left-right direction. The base 23a, outer masts 23b, 23b and inner masts 23c, 23c are supported between the pair of straddle legs 20b, 20b so as to be movable in the forward FD and rearward BD directions. 【0037】 The inner masts 23c, 23c are adjacent to the left and right inner sides of the outer masts 23b, 23b, respectively, and stand upright in the height direction. The inner masts 23c, 23c are supported by the outer masts 23b, 23b so that they can move relative to the outer masts 23b, 23b in the height direction. The fork assembly 24 is supported by the inner masts 23c, 23c so that it can move relative to the inner masts 23c, 23c in the height direction. Since the fork assembly 24 is supported by the outer masts 23b, 23b via the inner masts 23c, 23c, it can move forward FD and backward BD together with the outer masts 23b and inner masts 23c. 【0038】The fork assembly 24 includes a bracket 24a, a pair of forks 24b, 24b, and a backrest 24c. The bracket 24a is supported so as to be movable relative to the inner masts 23c, 23c in the height direction. The pair of forks 24b, 24b are mounted on the front of the bracket 24a. Each of the pair of forks 24b, 24b extends forward FD from the bracket 24a at a position where, for example, one outer mast 23b and one inner mast 23c are positioned in the left-right direction. The backrest 24c is mounted, for example, on the upper end of the bracket 24a. The backrest 24c prevents the load on the pallet being lifted by the forks 24b from falling backward from the fork assembly 24. 【0039】 Figure 3 is a schematic plan view showing the structure of a forklift 2 according to one specific example. Referring together to Figures 2 and 3, the forklift 2 further has, for example, three distance measuring sensors 25. The distance measuring sensors 25 are, for example, 2D LiDAR (optical detection and distance measuring) sensors. For example, one distance measuring sensor 25 is attached to the front end of each straddle leg 20b, while one distance measuring sensor 25 is attached to the rear end and lower end of the main body 20a. In this example, the three distance measuring sensors 25 are arranged at the same height from the floor. The front right distance measuring sensor 25 has a detection range R1 in the forward direction FD and the right direction RD. The front left distance measuring sensor 25 has a detection range R2 in the forward direction FD and the left direction LD. The rear distance measuring sensor 25 has a detection range R3 in the rear direction BD. 【0040】The detection ranges R1, R2, and R3 of these three distance measuring sensors 25 overlap with each other, and as a result, the three distance measuring sensors 25 have a 360-degree detection range R1, R2, and R3 around the axis defined in the height direction of the forklift 1. By irradiating these detection ranges R1, R2, and R2 with laser light, the three distance measuring sensors 25 acquire two-dimensional point cloud data of objects within their respective detection ranges R1, R2, and R3. The point cloud data consists of the coordinates and color information of each point, and the shape of objects within the detection range and the distance to the objects are detected by measuring the distance from the distance measuring sensor 25 to each point. The range of the detection ranges R1, R2, and R3 is set to, for example, 20m. According to these distance measuring sensors 25, a two-dimensional map of the arrangement layout of structures including temporary storage areas 14 and racks 15 is generated by mapping the lower floor 10 and upper floor 11 of the warehouse system 1. 【0041】 3. Diagram 4 of the Management Server Configuration is a functional block diagram schematically showing the control system of the management server 6. As shown in Figure 4, the warehouse system 1 has a management server 6 that manages the operation of the forklift 2, the storage status of items in the temporary storage area 14 and racks 15, etc., in relation to the receiving, storage, and dispatch of goods. This management is realized by the execution of a program stored in the storage unit by the control unit (computer). Specifically, these processes are executed according to the information processing described in the program. That is, the information processing described in the program functions as a concrete means in which the software related to the program and the various hardware resources of the warehouse system 1 cooperate when the program is read into the control unit. Such programs may be stored in a computer-readable storage medium. The management server 6 constitutes the item detection system according to the present invention. 【0042】The management server 6 comprises a control unit 61 and a storage unit 62. The control unit 61 comprises a communication control unit 63, an inventory management unit 64, and a transport control unit 65. The storage unit 62 stores a program 66 for controlling the processing of receiving, storing, and issuing goods in the warehouse system 1. In addition to the program 66, the storage unit 62 also stores information about the goods stored in the temporary storage area 14 and racks 15 (for example, information for managing which goods are stored where) and a two-dimensional map 67 showing the layout of the temporary storage area 14 and racks 15 in the warehouse system 1. The control unit 61 manages the warehouse system 1 by executing the program 66 stored in the storage unit 62. This management server 6 may be implemented as a physical server installed in the building where the warehouse system 1 is established, or as a cloud server built on the internet. 【0043】 The communication control unit 63 controls communication between the management server 6 and the forklift 2. The communication method may be, for example, Wi-Fi® or Bluetooth®. The inventory management unit 64 manages the inventory status of the warehouse system 1. Specifically, the inventory management unit 64 manages information for identifying each item (SKU), information for the number of items in stock identified by the SKU, and information for identifying the location where the item is stored (ID), etc., in association with each other. The transport control unit 65 manages and controls the operation of the forklift 2. Specifically, the transport control unit 65 generates transport instructions to tell the forklift 2 which item from which location in the warehouse system 1 should be transported to which location. 【0044】Specifically explaining the generation of the conveyance instruction in the conveyance control unit 65, the conveyance control unit 65 generates a conveyance instruction for a predetermined forklift 2 for each warehousing or shipping process in the warehouse system 1. The case of a conveyance instruction for moving goods only on the lower floor 10 or the upper floor 11 is as follows. In the conveyance instruction in this case, for example, a) the first movement path from the current position of the forklift 2 to the designated pallet 13, b) an instruction regarding the pick operation for picking up the designated pallet 13, c) the second movement path from the designated pallet 13 to the designated location for transporting the pallet, and d) an instruction regarding the drop operation for dropping the designated pallet 13 at the designated location are included. 【0045】 On the other hand, the case of a conveyance instruction from the lower floor 10 to the upper floor 11 or from the upper floor 11 to the lower floor 10 is as follows. Specifically, the conveyance instruction includes a first conveyance instruction to the forklift 2 arranged on one floor and a second conveyance instruction to the forklift 2 arranged on the other floor. The first conveyance instruction includes a) the first movement path from the current position of the forklift 2 to the designated pallet 13, b) an instruction regarding the pick operation for picking up the designated pallet 13, c) the second movement path to the conveyor 16b of the vertical conveyance device 16, and d) an instruction regarding the drop operation for dropping the designated pallet 13 onto the conveyor 16b. 【0046】 On the other hand, the second conveyance instruction includes a) the first movement path from the current position of the forklift 2 to the conveyor 16b of the vertical conveyance device 16, b) an instruction regarding the pick operation for picking up the designated pallet 13, c) the second movement path from the designated pallet 13 to the designated location for transporting the pallet, and d) an instruction regarding the drop operation for dropping the designated pallet 13 at the designated location. Thus, in the case of a conveyance instruction from the lower floor 10 to the upper floor 11 or from the upper floor 11 to the lower floor 10, the conveyance instruction is transmitted to different forklifts 2. Note that the first movement path and the second movement path do not have to be the shortest paths and may be approximate paths along which the forklift 2 can move on the map of the warehouse system 1. 【0047】4. Control System of Forklift Figure 5 is a functional block diagram schematically showing the control system of forklift 2. As shown in Figure 5, forklift 2 has a control unit 71 and a storage unit 72. The control unit 71 has a communication control unit 73 and a device control unit 74. In the storage unit 72, a program 75 for controlling the operation of forklift 2 is stored. In addition to the program 75, the storage unit 72 stores a two-dimensional map 76 showing the layout of the temporary storage area 14 and the rack 15 in the warehouse system 1. Note that this map 76 is shared with the management server 6. As described above, the map 76 is generated, for example, by forklift 2 mapping the lower floor 10 and the upper floor 11 using a ranging (2D LiDAR) sensor. The control unit 71 controls the operation of forklift 2 by executing the program 75 stored in the storage unit 72. 【0048】 The communication control unit 73 controls the communication between the management server 6 and the forklift 2. The device control unit 74 controls the operation of the forklift 2. Specifically, the device control unit 61 can control operations related to the forward and backward movement of the forklift 2 by driving the rear wheels, turning left and right, picking and dropping the pallet 13 by driving the mast assembly 23 and the fork assembly 24 of the cargo handling assembly 21. In addition, the device control unit 61 further manages a travel allowable area where the travel of the forklift 2 is allowed and a travel prohibited area where the travel of the forklift 2 is not allowed while the forklift 2 is traveling on the lower floor 10 and the upper floor 11. 【0049】5. Figure 6 of the temporary storage area configuration is a plan view that schematically shows the configuration of a temporary storage area 14 according to one specific example. As shown in Figure 6, in the map 76 generated by mapping by the forklift 2, a contour line CL is defined that shows the outline of the temporary storage area 14 in a plan view. The area within the contour line CL is defined as the detection area DR. In this example, the contour line CL is defined as a rectangle in a plan view. Specifically, the contour line CL is formed from a first long side CL1 and a second long side CL2 defined parallel to each other, and a first short side CL3 and a second short side CL4 defined parallel to each other. The first long side CL1 and the second long side CL2 and the first short side CL3 and the second short side CL4 are orthogonal to each other. However, the contour line CL may have different shapes in a plan view. 【0050】 In map 76, within the detection area DR of the contour line CL, multiple spots S1 to S12 (12 in this example) are defined, each containing a pallet 13 with multiple cardboard boxes 12 on it. One pallet 13 is placed in each spot S1 to S12. In this example, no pallets 13 are placed in spots S1, S3 to S6, S8 and S10 to S12, so in map 76, these spots S are defined as empty spots FS. Also, since pallets 13 are placed in spots S2, S7 and S8, these spots S are defined as occupied spots OS in map 76. In a plan view, the contours of each spot S1 to S12 coincide with, for example, the contour of a collection of four cardboard boxes 12. In this example, in a plan view, the contour of the collection of four cardboard boxes 12 roughly coincides with the contour of the pallet 13, so the pallet 13 is not visible. 【0051】In this temporary storage area 14, the entry directions of the autonomous forklift 2 and the manned forklift 4 into the detection area DR within the contour line CL are defined. For example, the forklift 2 can enter the detection area DR only from the side of the second long side CL2, along the first direction D1 which is perpendicular to the second long side CL2 of the contour line CL. On the other hand, for example, the manned forklift 4 can enter the detection area DR only from the side of the first long side CL1, along the second direction D2 which is perpendicular to the first long side CL1 of the contour line CL. The first direction D1 and the second direction D2 are defined to be in opposite directions. In this way, the forklift 2 and the manned forklift 4 can enter the detection area DR in different directions. In this way, interference, i.e., collision, due to overlapping work areas of the forklift 2 and the manned forklift 4 can be avoided. 【0052】 6. Object Detection by Forklift Next, we will explain the scenario in which the forklift 2 is in operation in the warehouse system 1. When the forklift 2 is in operation, it means that the power to the forklift 2 is turned on. When the power is on, for example, the forklift 2 is in the process of picking or dropping pallets 13, driving, turning, stopped, charging, etc. While the forklift 2 is in operation, the distance measuring sensor 25 acquires two-dimensional point cloud data (scan data) of objects within its detection range R1 to R3 by irradiating laser light into its detection range R1 to R3. This acquisition of scan data is performed, for example, at 1-second intervals. This scan data is stored in the memory unit 72 of the forklift 2 and processed by the control unit 71. The scan data is also stored in the memory unit 62 of the management server 6 via the communication control unit 73 and processed by the control unit 61. 【0053】In one example, when the forklift 2 is transporting a pallet 13 based on a transport instruction received from the management server 6, or when it is simply moving without transporting anything while waiting for a transport instruction, the forklift 2's distance sensor 25 continuously collects scan data within the detection range R1 to R3. This collection of scan data is performed as background processing in parallel with the detection of objects for the movement of the forklift 2. Figures 7A to 7C are plan views showing the scene in which the forklift 2 collects scan data while moving. As an example, the forklift 2 moves from one end of the detection area DR to the other, from the second short side CL4 to the first short side CL3 of the detection area DR, along the second long side CL2 of the contour line CL of the detection area DR. The movement speed is set to, for example, 1.4 m per second. During this movement, for example, the presence or absence of objects within the detection area DR is detected by the detection range R2 of the distance sensor 25 on the left front of the forklift 2 and the detection range R3 of the distance sensor 25 at the rear of the forklift 2. 【0054】 Specifically, while the forklift 2 is moving, the laser light emitted from the distance measuring sensor 25 is reflected from objects within the detection area DR and detected by the distance measuring sensor 25. The detected laser light, i.e., scan data, is then transmitted to the management server 6. The control unit 61 of the management server 6 generates a cost map. That is, as shown in Figure 7A, point cloud data PD representing the contour of the object is generated on the map 67, and this point cloud data PD is superimposed on the map 67. Specifically, the laser light irradiation generates point cloud data PD along the contour of the object. In this example, since the laser light is irradiated into the detection area DR from the second long side CL2, point cloud data PD is not generated on the back side of the first long side CL1 of the object. 【0055】Subsequently, as shown in Figure 7B, bounding boxes BB are formed, which are frames that enclose each point cloud data PD. In this example, rectangular bounding boxes BB are generated that enclose the point cloud data PD generated on the front and both sides of the object on the second long side CL2. Then, the generated bounding boxes BB are superimposed on the map 67. At this time, it is determined whether the dimensions of the bounding boxes BB are within the threshold range of the dimensions of the outline of the cardboard box 12. If the dimensions are within the threshold range, it is determined that the cardboard box 12, or pallet 13, is placed at the location where the bounding boxes BB were generated, i.e., at spot S. 【0056】 In this example, specifically, bounding boxes BB are generated at spots S2, S7, and S9, so it is detected that a cardboard box 12, or pallet 13, is placed at that spot S. As shown in Figure 7C, these spots S2, S7, and S9 are detected as occupied spots OS. On the other hand, spots S1, S3-S6, S8, and S10-S12, where it is not detected that a cardboard box 12 is placed, are detected as empty spots FS. In addition, spots S where it is not possible to determine the presence or absence of an object is identified, such as when another cardboard box 12 (pallet 13) is placed in front of the back cardboard box 12 (pallet 13) and the back cardboard box 12 (pallet 13) is obstructed, are identified as unknown spots US where the presence or absence of an object is unknown. However, unknown spots US are not shown in the examples in Figures 7A-7C. 【0057】The data generated in this way regarding occupied spots OS and empty spots FS within the detection area DR on the map 67 is stored in the storage unit 62 of the management server 6. In this way, the management server 6 can manage the data regarding spots S of each temporary storage area 14 collectively by aggregating the scan data transmitted from all forklifts 2. Alternatively, the latest data may be shared among multiple forklifts 2 by transmitting the data regarding spots S managed collectively to each forklift 2. On the other hand, the control unit 71 of each forklift 2 may process the scan data to generate data regarding occupied spots OS and empty spots FS within the detection area DR at each forklift 2. 【0058】 The data regarding occupied spot OS and empty spot FS described above is constantly updated based on the (latest) scan data acquired at one-second intervals. Therefore, even if, for example, another forklift 2 transports pallet 13 and the cardboard box 12 is removed from spot S, the occupied spot OS and empty spot FS are always detected by the latest scan data. On the other hand, after a predetermined time has elapsed since the determination, the occupied spot OS and empty spot FS may be changed to an unknown spot US. In this way, for example, if scan data is not acquired for a predetermined period of time, it may be determined that the presence or absence of an object at spot S is unknown. In this example, scan data was collected while forklift 2 was moving along the second long side CL2 of the contour line CL of the detection area DR, but scan data may also be collected while moving along the first long side CL1, the first short side CL3, or the second short side CL4 of the contour line CL. 【0059】It is assumed that objects such as pillars, workers 3, manned forklifts 4, and other transport robots 5 may be located within or entering the contour line CL of the detection area DR. In this case, for example, if it is a pillar, information regarding the pillar's position and contour is predetermined on the map 76, so even if a pillar is detected as an object, it can be easily identified as a pillar. Also, since scan data is collected at 1-second intervals, workers 3, manned forklifts 4, and other transport robots 5 that are moving within the detection area DR can be detected separately from cardboard boxes 12, i.e., pallets 13. In other words, these objects can be easily excluded from the detection of occupied spots OS and empty spots FS. 【0060】 7. An Example of Forklift Operation Figure 8 is a plan view illustrating an example of forklift 2's operation. In this example, an example of forklift 2's operation is described, for example, picking up a pallet 13 from one temporary storage area 14 (first temporary storage area 14A) and dropping the pallet 13 into another temporary storage area 14 (second temporary storage area 14B). As mentioned above, in the warehouse system 1, all forklifts 2 constantly detect the presence or absence of cardboard boxes 12 (pallets 13) at each spot S within the detection area DR of each temporary storage area 14. In this way, it is determined whether each spot S is an occupied spot OS, an empty spot FS, or an unknown spot US. This data regarding spots S is managed and analyzed collectively by the management server 6 to provide a more accurate classification of each spot S. 【0061】If the status of a spot S in the temporary storage area 14 (occupied spot OS, empty spot FS, or unknown spot US) is unknown, the spot S with an unknown status is labeled, for example, "search spot". To enable the appropriate status classification of the spot S labeled as a search spot, one or more forklifts 2 may be assigned to collect scan data from the temporary storage area 14, including the search spot S. The status of all spots S in the temporary storage area 14 is collected by the assigned one or more forklifts 2 moving around the temporary storage area 14 and collecting scan data. In addition, data regarding the status of spots S in the temporary storage area 14 may be collected from other sources, such as visual observation by a worker 3 or distance sensors on a manned forklift 4. 【0062】 In the example shown in Figure 8, at the first temporary storage area 14A, the source of transport, spots S1, S4-S9, and S11, where cardboard boxes 12 (pallets 13) are detected to be placed, are identified as occupied spots OS. Spots S10 and S12, where cardboard boxes 12 (pallets 13) are detected not to be placed, are identified as empty spots S. On the other hand, spots S2 and S3, where the presence or absence of cardboard boxes 12 (pallets 13) could not be determined even through the collection of scan data, are detected as unknown spots US. At the second temporary storage area 14B, the destination of transport, since cardboard boxes 12 (pallets 13) are not placed at any of the spots S, all spots S are detected as empty spots FS. Note that in Figure 8, since the outlines of the four cardboard boxes 12 are the same as the outlines of the pallets 13, only the outlines of the four cardboard boxes 12 are shown. 【0063】A user (administrator) of the warehouse system 1 can instruct a forklift 2 to operate via an input device (not shown) such as a display or keyboard on the management server 6. Specifically, an instruction is generated to transport a pallet 13 from the first temporary storage area 14A to the second temporary storage area 14B. However, the user only needs to select which temporary storage area 14 is the first temporary storage area 14A and which temporary storage area 14B is the second temporary storage area. Once the first temporary storage area 14A (source) and the second temporary storage area 14B (destination) are selected, the control unit 61 of the management server 6 transmits a transport instruction to a predetermined forklift 2. For example, the transport instruction is transmitted to two forklifts 2 located within a predetermined distance from the first temporary storage area 14A. 【0064】 Upon receiving a transport instruction, the forklift 2 moves toward the designated first temporary storage area 14A. Even while moving toward the first temporary storage area 14A, the collection of scan data by the distance measuring sensor 25 is continuously performed. Upon arrival at the first temporary storage area 14A, the forklift 2 performs a scan of the detection area DR of the first temporary storage area 14A. The latest scan data thus collected is transmitted to the management server 6, updating the data indicating whether each spot S in the detection area DR is an occupied spot OS, an empty spot FS, or an unknown spot US. In the example shown in Figure 8, this new scan detects, for example, the unknown spots US of spots S2 and S3 as empty spots FS. Note that the detection of objects in areas outside the detection area DR is not used in detecting the state of the spots S. 【0065】The two forklifts 2 assigned to the first temporary storage area 14A pick up the pallet 13 closest to the current position of each forklift 2 based on data feedback from the management server 6. For example, in the state shown in Figure 8, the forklift 2 picks up the pallet 13 from spot S11. The forklift 2 then moves from the first temporary storage area 14A to the destination, the second temporary storage area 14B. Upon arriving at the second temporary storage area 14B, the forklift 2 performs a scan of the detection area DR of the second temporary storage area 14B. The latest scan data collected in this way is transmitted to the management server 6, which updates the data indicating whether each spot S in the detection area DR is an occupied spot OS, an empty spot FS, or an unknown spot US. In this example, all spots S are updated to empty spots FS. 【0066】 Based on data feedback from the management server 6, the forklift 2 drops the pallet 13 to the available spot FS furthest from the second long side CL2 (in this example, one of spots S1 to S4). In this way, the pallets 13 are sequentially placed from the spots S at the back to the spots S at the front of the second temporary storage area 14B. Subsequently, the forklift 2 repeats the transport operation of the pallets 13 from the first temporary storage area 14A to the second temporary storage area 14B, for example, until there are no occupied spots OS in the detection area DR of the first temporary storage area 14A, or until there are no available spots FS in the detection area DR of the second temporary storage area 14B. In the example in Figure 8, the transport operation continues until the pallets 13 at spots S2, S4 to S9 and S11 of the first temporary storage area 14A are transported to one of the spots S in the second temporary storage area 14B. During this transport operation, the forklift 2's distance measuring sensor 25 continuously collects scan data, so the status of spot S in the detection area DR in the warehouse system 1 is constantly updated. 【0067】8. Technical Advantages In the warehouse system 1 described above, objects within the detection area DR, namely cardboard boxes 12 and pallets 13, are detected based on scan data collected by an autonomous forklift 2, which is a mobile unit, by scanning the detection area DR at predetermined time intervals (e.g., every second). Therefore, objects can be detected with higher accuracy than before. Moreover, since scan data is collected continuously while the forklift 2 is in operation, the status of spots S within the detection area DR can always be updated to the latest state. As a result, for example, pallets 13 can be transported efficiently and reliably from the first temporary storage area 14 to the second temporary storage area 14. In addition, since scan data collected from multiple forklifts 2 is analyzed by the management server 6, the status of spots S within each detection area DR can be detected more accurately. 【0068】 9. Modifications and Others: In the warehouse system 1, distance measuring sensors mounted on, for example, a manned forklift 4 or other transport robot 5 may be used to collect scan data. Similar to the forklift 2, scan data may be collected continuously while the manned forklift 4 or other transport robot 5 is in operation. For example, by having the manned forklift 4 collect scan data from a different direction than the forklift 2, the state of spot S in the detection area DR can be determined with even higher accuracy. That is, the probability of unknown spot US occurring within the detection area DR can be reduced. Furthermore, with the manned forklift 4, for example, a worker 3 can drive it and scan the detection area DR from the optimal direction, so scan data can be collected even more efficiently. In this way, by collecting scan data not only from the forklift 2 but also from the manned forklift 4 and other transport robots 5, the status of spot S can be detected more accurately. 【0069】The detection area DR does not necessarily have to be an area defined within the temporary storage area 14; for example, it may be an area defined on the rack 15 or the conveyor 16b. If it is a rack 15, for example, one storage space 15c may constitute one spot S. Although not shown in Figure 1, the detection area DR may also be an area within the space where a truck vehicle parks to transport cardboard boxes 12, i.e., pallets 13, to the warehouse system 1. Furthermore, a 3D LiDAR sensor may be used instead of a 2D LiDAR sensor for the distance measuring sensor 25. With this 3D LiDAR sensor, it is possible to acquire three-dimensional point cloud data showing the contour of an object, thus suppressing false detection of objects, i.e., cardboard boxes 12 and / or pallets 13. Specifically, since the 3D LiDAR sensor can instantly detect the height of an object, the transport operation can be made more efficient by, for example, detecting the number of pallets 13 stacked in the height direction. 【0070】 Furthermore, it is conceivable that, for example, a cardboard box 12, or pallet 13, is not placed at the predetermined location of spot S within the detection area DR. Specifically, for example, it is possible to detect that the object is a cardboard box 12 (pallet 13) from the dimensions of the cardboard box 12, but the pallet 13 may be misaligned from the predetermined location of spot S. In this case, an error may be considered to have occurred for spot S, and the transport process may be terminated. After that, the transport process may be resumed when the pallet 13 is placed at the predetermined location. The same process may be applied if an object other than a cardboard box 12 (pallet 13) is placed at spot S. 【0071】Furthermore, although the above embodiment described the case of transporting a pallet 13 from one first temporary storage area 14A to one second temporary storage area 14B, other cases such as transporting a pallet 13 from multiple first temporary storage areas 14A to one second temporary storage area 14B, transporting a pallet 13 from one first temporary storage area 14A to multiple second temporary storage areas 14B, or transporting a pallet 13 from multiple first temporary storage areas 14A to multiple second temporary storage areas 14B are also conceivable. In addition, these pallet transport operations may be performed by a manned forklift 4 in addition to the forklift 2. Also, for example, if an error occurs in the collection of scan data by a forklift 2, another forklift 2 may continue collecting scan data from the location where the error occurred. 【0072】 10. Applicable Subject Matter In the above description of the embodiments, the warehouse system 1 was used as an example of the applicable subject of the present invention, but the present invention is applicable to other subjects as well. For example, the mobile body may be an autonomous vehicle, and the detection area may be a parking lot for parking autonomous vehicles. Specifically, one example is to collect scan data acquired by distance measuring sensors mounted on multiple autonomous vehicles to detect whether or not a vehicle is parked in each parking space (i.e., spot) in the parking lot. By sharing this scan data of available parking spaces among multiple autonomous vehicles, the drivers of the autonomous vehicles can efficiently find available parking spaces. 【0073】 Throughout all drawings, the same reference numerals are used to refer to identical or similar components. The following embodiments are not intended to limit the invention described in the claims. While the features of the invention are described herein, they can be modified and altered without departing from the spirit and scope of the disclosed embodiments. Furthermore, certain features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. The following detailed description is for illustrative purposes only, and the true scope and spirit are intended to be shown by the claims.

Claims

1. An object detection method for detecting objects placed in a plurality of spots defined within a predetermined detection area, the method comprising: causing a computer to perform the steps of: collecting scan data from one or more moving objects that scan the detection area at predetermined time intervals; and, based on the scan data, detecting occupied spots in the plurality of spots within the detection area where the object is placed and empty spots where the object is not placed.

2. The object detection method according to claim 1, wherein the occupied spot and the empty spot are updated based on the latest scan data.

3. The object detection method according to claim 1, wherein the computer further performs the step of changing the occupied spot and the empty spot to an unknown spot where it is unknown whether or not the object is located, after a predetermined time has elapsed since the detection of the occupied spot and the empty spot.

4. The object detection method according to claim 3, further comprising causing the computer to perform the step of updating the unknown spot to the occupied spot or the vacant spot based on the scan data collected from the one or more moving objects.

5. The object detection method according to claim 4, wherein the scan data is collected during the operation of the moving body.

6. The object detection method according to claim 1, wherein the scan data is continuously collected while the moving body is in motion.

7. The object detection method according to claim 1, further comprising the step of causing the computer to detect unknown spots where the presence or absence of the object is unknown, based on the scan data.

8. The object detection method according to claim 1, further comprising the step of instructing the computer to transport the object located at the occupied spot within the detection area.

9. The object detection method according to claim 8, wherein the instruction is an instruction to transport the object to an empty spot in another detection area.

10. The object detection method according to claim 8, further comprising the step of causing the computer to update the occupied spot and the empty spot based on the scan data collected from the moving body engaged in the transport of the object.

11. The object detection method according to claim 1, further comprising the step of instructing the computer to transport the object to the empty spot within the detection area.

12. The object detection method according to claim 11, wherein the instruction is an instruction to transport the object from the occupied spot in another detection area.

13. The object detection method according to claim 11, further comprising the step of causing the computer to update the occupied spot and the empty spot based on the scan data collected from the moving body engaged in the transport of the object.

14. The object detection method according to claim 1, wherein the moving body is an autonomous moving body.

15. The method for detecting an object according to claim 14, wherein the moving body is an autonomous forklift capable of autonomous movement, and the object is an article placed on a pallet.

16. The method for detecting an object according to claim 1, wherein the moving body is a manned forklift operated by an operator, and the object is an article placed on a pallet.

17. An object detection system configured to perform the object detection method described in any one of claims 1 to 16.

18. A computer-readable medium including an instruction causing a computer to perform the object detection method described in any one of claims 1 to 16.

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