Cargo Handling System

Abstract

To provide a loading / unloading system that prevents a sensor for detecting a to-be-detected object positioned in front of a fork supporting goods from colliding with another object when a forklift travels and that is able to detect the to-be detected object accurately.SOLUTION: A loading / unloading system includes: a forklift 1 that performs loading / unloading; and a rack that stores goods. The forklift 1 includes: a pair of left and right forks 11R, 11L configured to handle the goods; a right photoelectric sensor 13R of a reflection type provided at a distal end of a right fork 11R disposed on the right side, and configured to receive infrared light; a left photoelectric sensor 13L of a reflection type provided at a distal end of a left fork 11L disposed on the left side, and configured to emit and receive infrared light; and a side shift device 12 configured to move the forks 11R, 11L in a Y direction (rightward and leftward directions), based on light reception and projection results of the photoelectric sensors 13R, 13L. In addition, the rack includes a reflector configured to reflect the infrared light projected by each of the photoelectric sensors 13R, 13L.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a cargo handling system that automatically adjusts the positions of a pair of left and right forks. [Background technology]

[0002] Patent Document 1 describes a forklift equipped with a cargo handling device having forks and side shift cylinders, and a cargo handling control device that controls cargo handling. The cargo handling control device has laser distance sensors installed on both the left and right sides of the cargo handling device, determines the loading start position or cargo placement start position of the forks based on the detection values of the laser distance sensors, and controls the side shift cylinder according to the determined loading start position or cargo placement start position. The left and right laser distance sensors are positioned at a distance greater than the maximum width dimension of the pallet supported by the forks, and are located behind the front of the backrest located behind the forks. With this configuration, the laser distance sensors can detect a detection target located in front of the forks even when the forks are supporting a load.

[0003] However, in the above-mentioned Patent Document 1, the laser distance sensor is provided at a position that protrudes in the left and right directions from the cargo handling device, so there is a risk that the laser distance sensor may collide with other objects when the forklift travels through a narrow passage. Also, because the distance from the laser distance sensor to the detection target is long, there is a risk that the detection target may not be detected accurately if the forklift is misoriented. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7156174 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the above circumstances, and has an object to provide a cargo handling system in which a sensor for detecting a detection target located in front of the forks when the forks are supporting a load does not collide with other objects when the forklift is traveling, and can accurately detect the detection target. [Means for solving the problem]

[0006] In order to solve the above problems, the cargo handling system of the present invention comprises a forklift truck that performs cargo handling, and a cargo support section on which cargo is placed, wherein the forklift truck comprises a pair of left and right forks that handle the cargo, a side shifting device that moves the forks left and right, a reflective right photoelectric sensor that is provided at the tip of the right fork on the right side of the forks and that emits and receives light, a reflective left photoelectric sensor that is provided at the tip of the left fork on the left side of the forks and that emits and receives light, and a control device that controls the side shifting device based on the light emission and reception results of the right photoelectric sensor and the left photoelectric sensor, and the cargo support section is characterized in that it comprises a reflector that reflects the light emitted by the right photoelectric sensor and the left photoelectric sensor.

[0007] It is also preferable that the reflector changes the polarization state of light incident on the reflector and reflects it, and that the right photoelectric sensor and the left photoelectric sensor detect the reflector by projecting light of a predetermined polarization state and receiving light of a polarization state different from the predetermined polarization state.

[0008] It is also preferable that the reflector reflects light incident on the reflector in the direction from which the light came.

[0009] Preferably, the right photoelectric sensor and the left photoelectric sensor emit and receive infrared light.

[0010] It is also preferable that the distance from the right end to the left end of the reflector is greater than the distance between the right photoelectric sensor and the left photoelectric sensor.

[0011] Furthermore, it is preferable that the control device controls the side shift device to move the fork in the direction in which the right photoelectric sensor or the left photoelectric sensor is located when only one of the right photoelectric sensor and the left photoelectric sensor receives light reflected by the reflector, and controls the side shift device to stop the movement of the fork when both sensors receive light reflected by the reflector. [Effects of the Invention]

[0012] According to the present invention, a cargo handling system can be provided in which a sensor for detecting a detection target located in front of the forks when the forks are supporting a load does not collide with other objects when the forklift is traveling and can accurately detect the detection target. [Brief explanation of the drawings]

[0013] [Figure 1] 1A and 1B are schematic diagrams of a cargo handling system according to an embodiment of the present invention, in which (A) is a side view of a forklift and a cargo support unit according to the embodiment, and (B) is a plan view thereof. [Figure 2] FIG. 2A is a block diagram showing a schematic configuration of the forklift, and FIG. 2B is a plan view showing the arrangement of photoelectric sensors provided in the forklift. [Figure 3] FIG. 2 is a perspective view of a rack serving as a luggage support unit according to the embodiment. [Figure 4] FIG. 1A is a front view of the rack, and FIG. 1B is an enlarged view showing the arrangement of reflectors provided on the rack. [Figure 5] 10 is a flowchart of a side shift process performed by a control device provided in the forklift. [Figure 6] FIG. 10 is a schematic diagram of a cargo handling system according to a modified example, and is a plan view of a forklift and a cargo support unit according to the modified example. DETAILED DESCRIPTION OF THE INVENTION

[0014] A cargo handling system according to one embodiment of the present invention will be described with reference to Figures 1 to 5. Note that the X, Y, and Z directions indicated by arrows in the figures are linear directions that are perpendicular to one another, and the Z direction is the vertical direction.

[0015] As shown in Figures 1(A) and 1(B), the material handling system includes a forklift 1 and a pallet rack 2 (hereinafter referred to as "rack 2"). The material handling system is constructed in an unmanned warehouse where in-warehouse operations are unmanned, or an automated warehouse where in-warehouse operations are automated.

[0016] The forklift 1 is composed of a vehicle body 1A and a cargo handling device 1B. The forklift 1 performs cargo handling operations, including picking up, transporting, and placing cargo (not shown). The forklift 1 according to this embodiment is a reach-type unmanned forklift that automatically handles cargo.

[0017] The vehicle body 1A is a traveling body that can move straight in the X direction. To transport luggage, the vehicle body 1A estimates its own vehicle position and travels autonomously along a predetermined travel route. That is, the vehicle body 1A includes a position estimation device that estimates the vehicle position and a traveling device that travels autonomously.

[0018] The forklift 1 includes a pair of left and right forks 11R, 11L for handling cargo as components of the cargo handling device 1B. The forks 11R, 11L are claws that can be inserted into a pallet (not shown) on which cargo is placed. The right fork 11R on the right side and the left fork 11L on the left side are spaced a predetermined distance from each other in the Y direction, which is the left-right direction, and extend parallel to each other in the X direction. The forks 11R, 11L are configured to be movable in three directions, the X direction, Y direction, and Z direction, relative to the vehicle body 1A.

[0019] As shown in FIG. 2(A), the forklift 1 also includes a side shift device 12, photoelectric sensors 13R and 13L, a notification device 14, and a control device 15.

[0020] The side shift device 12 moves the forks 11R, 11L in the left-right direction, that is, the Y direction. By moving the forks 11R, 11L relative to the vehicle body 1A, the side shift device 12 adjusts the positions of the forks 11R, 11L in the Y direction without moving the vehicle body 1A.

[0021] The photoelectric sensors 13R, 13L are retro-reflective infrared sensors that emit and receive infrared light, not laser light. Specifically, the photoelectric sensors 13R, 13L emit linearly polarized infrared light (light with a predetermined polarization state) containing only a predetermined polarization component, and receive the infrared light reflected by a detection target located in front of the forks 11R, 11L. At this time, the photoelectric sensors 13R, 13L detect the detection target by receiving infrared light with a polarization state different from that of the emitted infrared light.

[0022] When an abnormality occurs, the notification device 14 notifies the manager that it is necessary to restore the forklift 1. The notification device 14 is configured, for example, by an acoustic device that emits sound, a light-emitting device that emits light, or a communication device that transmits a notification signal to a remote device (not shown) located away from the forklift 1.

[0023] The control device 15 performs a side shifting process in a loading operation of placing a load on the rack 2 and in a loading operation of removing a load from the rack 2. In the side shifting process, the control device 15 controls the side shift device 12 based on the results of light emission and reception by the photoelectric sensors 13R and 13L. By controlling the side shift device 12, the control device 15 adjusts the positions of the forks 11R and 11L in the Y direction via the side shift device 12. The side shifting process will be described later with reference to FIG. 5.

[0024] As shown in FIG. 2(B), the photoelectric sensors 13R, 13L are provided at the tips of the forks 11R, 11L. That is, the right photoelectric sensor 13R provided on the right side is provided at the tip of the right fork 11R, and the left photoelectric sensor 13L provided on the left side is provided at the tip of the left fork 11L. In this way, the distance D1 between the right photoelectric sensor 13R and the left photoelectric sensor 13L is configured to be a predetermined distance. The distance D1 is the distance between the optical axes of the infrared rays emitted and received by the photoelectric sensors 13R, 13L.

[0025] 3 and 4(A), the rack 2 includes a support 21, a beam 22, a sub-beam 23, and a plurality of reflectors 24R and 24L. The rack 2 is a luggage support portion on which luggage is placed, and supports the luggage from below.

[0026] The support columns 21 are vertical members extending in the Z direction. The beams 22 are horizontal members extending in the Y direction, connecting a pair of support columns 21 extending parallel to the Z direction. The sub-beams 23 are horizontal members extending in the X direction, connecting a pair of beams 22 extending parallel to the Y direction. The beams 22 and sub-beams 23 function as shelves that support luggage.

[0027] The rack 2 according to this embodiment has four shelves, and above each shelf there is a luggage space A where luggage can be placed. The rack 2 also has two luggage spaces A per shelf so that luggage can be lined up in the Y direction on one shelf.

[0028] The rack 2 also includes a pair of left and right reflectors 24R, 24L corresponding to each of the luggage spaces A. The reflectors 24R, 24L are spaced apart in the Y direction and are provided on the beam 22 located directly below the corresponding luggage space A.

[0029] The reflectors 24R, 24L are reflective materials that reflect infrared rays projected by the photoelectric sensors 13R, 13L. Specifically, the reflectors 24R, 24L are aggregates of corner cubes that change the polarization state of infrared rays incident on the reflectors 24R, 24L and reflect the infrared rays incident on the reflectors 24R, 24L back in the direction from which they were incident. The right reflector 24R provided on the right side is the detection target of the right photoelectric sensor 13R, and the reflector 24L provided on the left side is the detection target of the left photoelectric sensor 13L.

[0030] 4(B), the distance D2 from the right end to the left end of the reflectors 24R, 24L, i.e., the distance D2 from the right end of the right reflector 24R to the left end of the left reflector 24L, is configured to be larger than the distance D1 between the right photoelectric sensor 13R and the left photoelectric sensor 13L. Also, the distance D3 between the reflectors 24R, 24L, i.e., the distance D3 from the left end of the right reflector 24R to the right end of the left reflector 24L, is configured to be smaller than the distance D1 between the right photoelectric sensor 13R and the left photoelectric sensor 13L.

[0031] 5, the flow of the side shift process performed by the control device 15 will be described. The side shift process is performed when the forks 11R, 11L and the beam 22 located directly below the desired luggage space A are located on the same horizontal plane (i.e., when the ground clearances of the photoelectric sensors 13R, 13L and the reflectors 24R, 24L are the same).

[0032] First, the control device 15 determines whether both the photoelectric sensors 13R, 13L have detected the reflectors 24R, 24L (step S1). If both the photoelectric sensors 13R, 13L have detected the reflectors 24R, 24L (step S1: YES), the control device 15 determines that the positions of the forks 11R, 11L in the Y direction are appropriate for the desired luggage space A, and ends the side shift process without operating the side shift device 12 (i.e., without adjusting the positions of the forks 11R, 11L).

[0033] If neither of the photoelectric sensors 13R, 13L has detected the reflectors 24R, 24L (step S1: NO), the control device 15 determines whether one of the photoelectric sensors 13R, 13L has detected the reflectors 24R, 24L (step S2).

[0034] If one of the photoelectric sensors 13R, 13L does not detect the reflectors 24R, 24L (step S2: NO), that is, if neither of the photoelectric sensors 13R, 13L detects the reflectors 24R, 24L, the control device 15 controls the alarm device 14 to alarm the failure to detect the reflectors 24R, 24L (step S10). After the alarm is issued in step S10, the control device 15 determines that the stopping position of the vehicle body 1A is inappropriate, and terminates the side shift process without operating the side shift device 12. The forklift 1 then makes an emergency stop, thereby halting the loading and unloading process.

[0035] On the other hand, if one of the photoelectric sensors 13R, 13L detects the reflector 24R, 24L (step S2: YES), the control device 15 controls the side shift device 12 to move the forks 11R, 11L in the left-right direction, that is, the Y direction (step S3). At this time, the control device 15 controls the side shift device 12 to move the forks 11R, 11L in the direction of the one of the photoelectric sensors 13R, 13L that received infrared light reflected by the reflector 24R, 24L. That is, when only the right photoelectric sensor 13R receives infrared light reflected by the reflector 24R, the side shift device 12 moves the forks 11R, 11L to the right, and when only the left photoelectric sensor 13L receives infrared light reflected by the reflector 24L, the side shift device 12 moves the forks 11R, 11L to the left.

[0036] Next, the control device 15 determines whether the other of the photoelectric sensors 13R, 13L (i.e., the one that did not detect the reflectors 24R, 24L) detected the reflectors 24R, 24L as a result of the movement of the forks 11R, 11L (step S4). If the other of the photoelectric sensors 13R, 13L did not detect the reflectors 24R, 24L (step S4: NO), the control device 15 repeats the processes from step S3 onwards to control the side shift device 12 so that the forks 11R, 11L continue to move in the Y direction.

[0037] On the other hand, if the other of the photoelectric sensors 13R, 13L detects the reflectors 24R, 24L (step S4: YES), that is, if both of the photoelectric sensors 13R, 13L receive infrared light reflected by the reflectors 24R, 24L, the control device 15 controls the side shift device 12 to stop the movement of the forks 11R, 11L in the Y direction (step S5). That is, when both of the photoelectric sensors 13R, 13L receive infrared light reflected by the reflectors 24R, 24L, the side shift device 12 stops the movement of the forks 11R, 11L.

[0038] By performing the side shift process in the above manner, the photoelectric sensors 13R, 13L and the reflectors 24R, 24L can be made to face each other, and the positions of the forks 11R, 11L can be appropriately adjusted with respect to the luggage space A located directly above the reflectors 24R, 24L. Therefore, luggage can be appropriately placed in the luggage space A during a luggage placement operation, and luggage can be appropriately removed from the luggage space A during a luggage removal operation.

[0039] In this embodiment, the following effects are obtained. (1) Because the photoelectric sensors 13R, 13L are provided at the respective tips of the pair of left and right forks 11R, 11L, they can be configured not to protrude in the Y direction (left-right direction) from the forks 11R, 11L, and the distance from the photoelectric sensors 13R, 13L to the reflectors 24R, 24L that are the detection targets can be shortened. Therefore, a cargo handling system can be realized in which the photoelectric sensors 13R, 13L, which are used to detect targets located in front of the forks 11R, 11L when the forks 11R, 11L are supporting a load, do not collide with other objects when the forklift 1 is traveling, and can accurately detect the reflectors 24R, 24L.

[0040] (2) The photoelectric sensors 13R and 13L detect the reflectors 24R and 24L by projecting linearly polarized infrared light (light with a predetermined polarization state) and receiving infrared light with a polarization state different from the linearly polarized infrared light. Therefore, even if the infrared light projected by the photoelectric sensors 13R and 13L is specularly reflected by the beam 22, the polarization state of the infrared light is the same before and after the specular reflection, so it is possible to distinguish between the beam 22, which is not the target of detection, and the reflectors 24R and 24L, which are the target of detection.

[0041] (3) The reflectors 24R, 24L reflect the infrared rays incident on the reflectors 24R, 24L in the direction from which they were incident. Therefore, even if the infrared rays emitted by the photoelectric sensors 13R, 13L are not incident perpendicularly to the reflectors 24R, 24L, the reflectors 24R, 24L can be detected.

[0042] (4) Because the photoelectric sensors 13R and 13L emit and receive infrared light, they are less susceptible to disturbance light than sensors that emit and receive visible light. In addition, because the photoelectric sensors 13R and 13L emit and receive natural light, rather than laser light, they can be manufactured at lower costs than sensors that emit and receive laser light.

[0043] (5) Since the distance D2 from the right end to the left end of the reflectors 24R and 24L is greater than the distance D1 between the right photoelectric sensor 13R and the left photoelectric sensor 13L, both photoelectric sensors 13R and 13L can simultaneously receive the infrared rays reflected by the reflectors 24R and 24L.

[0044] (6) The reflectors 24R and 24L are spaced apart in the Y direction, so that the detection targets of the photoelectric sensors 13R and 13L are made smaller, thereby reducing the cost of the rack 2.

[0045] The present invention is not limited to the above-described embodiment, and the above configurations can be modified. For example, the following modifications can be made, or the following modifications can be combined to make the present invention.

[0046] The configuration of the reflectors 24R, 24L may be changed as appropriate. Specifically, for example, the rack 2 may be provided with a single reflector (not shown) having a width of a distance D2 from the right end to the left end of the reflectors 24R, 24L, instead of the pair of left and right reflectors 24R, 24L, as reflectors corresponding to each of the luggage spaces A.

[0047] The configuration of the photoelectric sensors 13R, 13L may be modified as appropriate. Specifically, for example, the photoelectric sensors 13R, 13L may emit and receive visible light or infrared laser light. Furthermore, for example, the photoelectric sensors 13R, 13L may function as distance sensors and detect the reflectors 24R, 24L by receiving light reflected at a position a predetermined distance from the photoelectric sensors 13R, 13L. In this case, even if the light emitted by the photoelectric sensors 13R, 13L is reflected by the beam 22, the distance from the photoelectric sensors 13R, 13L to the beam 22 is different from the distance from the photoelectric sensors 13R, 13L to the reflectors 24R, 24L provided on the beam 22, making it possible to distinguish between the beam 22, which is not the target of detection, and the reflectors 24R, 24L, which are the target of detection.

[0048] As shown in Fig. 6, the present invention may be applied to a forklift 1' whose vehicle body 1A is capable of moving straight in the Y direction. In this case, the side shift device 12 is configured as a traveling device that moves the vehicle body 1A in the Y direction, and adjusts the positions of the forks 11R, 11L in the Y direction by moving the vehicle body 1A straight in the Y direction (i.e., by traveling).

[0049] The details of the side shift process may be modified as appropriate if the movement of the forks 11R, 11L is controlled in response to the detection of the reflectors 24R, 24L. Specifically, for example, in step S5, the control device 15 may control the side shift device 12 so that when both the photoelectric sensors 13R, 13L receive infrared light reflected by the reflectors 24R, 24L, the forks 11R, 11L move a predetermined distance and then stop the movement of the forks 11R, 11L. In other words, when both the photoelectric sensors 13R, 13L receive infrared light reflected by the reflectors 24R, 24L, the movement of the forks 11R, 11L does not have to be immediately stopped. In this case, the side shift device 12 preferably includes a potentiometer (not shown) for detecting the amount of movement of the forks 11R, 11L.

[0050] The luggage support unit does not have to be the rack 2. Specifically, for example, the luggage support unit may be the loading platform of a truck (not shown), which is a freight vehicle, or the loading platform of a loading / unloading station (not shown).

[0051] The forklift 1 may be equipped with three or more forks (not shown). In this case, at least two of the three or more forks function as a pair of left and right forks, and photoelectric sensors that function similarly to the photoelectric sensors 13R and 13L are provided at the tips of the forks.

[0052] The forklift 1 may be a manned forklift configured to be able to travel and handle cargo by operation of an operator, or may be a manned / unmanned forklift that can operate as both a manned and unmanned forklift by switching the operating mode. [Explanation of symbols]

[0053] 1 forklift 2 Pallet rack (load support part) 1A Vehicle body 1B Cargo handling equipment 11R Right Fork (Fork) 11L Left fork (fork) 12 Side shift device 13R Right photoelectric sensor (photoelectric sensor) 13L Left photoelectric sensor (photoelectric sensor) 15 Control device 22 Beam 24R Right Reflector (Reflector) 24L Left reflector (reflector) A. Luggage space

Claims

1. Forklifts for loading and unloading, a luggage support portion on which luggage is placed, The forklift A pair of left and right forks for handling the luggage; a side shift device that moves the fork in the left-right direction; a reflective right photoelectric sensor that is provided at the tip of the right fork of the forks and that emits and receives light; a reflective left photoelectric sensor that is provided at the tip of the left fork of the forks and that emits and receives light; a control device that controls the side shift device based on a light emission and reception result of the right photoelectric sensor and a light emission and reception result of the left photoelectric sensor, The luggage support portion is A pair of front and rear beams that function as shelves for supporting the luggage and are horizontal members extending in the left-right direction and are spaced apart in the front-rear direction perpendicular to the left-right direction; a reflector provided on the front beam of the pair of front and rear beams that is closer to the forklift, the reflector reflecting light emitted by the right photoelectric sensor and the left photoelectric sensor; The luggage support portion has a luggage space above the pair of front and rear beams in which the luggage can be placed, and the reflector is provided on a part of a front surface of the front beam located directly below the luggage space and facing the fork, When the fork and the front beam are positioned on the same horizontal plane, and only one of the right photoelectric sensor and the left photoelectric sensor receives light reflected by the reflector, the control device controls the side shift device to move the fork in the direction in which the one of the right photoelectric sensor and the left photoelectric sensor is disposed, and when both sensors receive light reflected by the reflectors, the control device controls the side shift device to stop the movement of the fork. A cargo handling system characterized by:

2. The reflector changes the polarization state of light incident on the reflector and reflects the light, The right photoelectric sensor and the left photoelectric sensor detect the reflector by projecting light with a predetermined polarization state and receiving light with a polarization state different from the projected polarization state.

2. The cargo handling system according to claim 1.

3. The reflector reflects the light incident on the reflector in the direction from which it was incident.

3. The cargo handling system according to claim 2.

4. The right photoelectric sensor and the left photoelectric sensor emit and receive infrared light.

2. The cargo handling system according to claim 1.

5. The distance from the right end to the left end of the reflector is greater than the distance between the right photoelectric sensor and the left photoelectric sensor.

2. The cargo handling system according to claim 1.

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