Method for dealing with floor inclination and system for dealing with floor inclination

Abstract

To provide a floor slope coping method which automatically measures the inclination of a floor surface at a stopping position where an unmanned forklift stops to put down a cargo to shift a traveling center of the unmanned forklift at the stopping position as needed.SOLUTION: A slope coping method 2 comprises automatically measuring an inclination angle in a rack right and left direction of a floor at the stopping position using a clinometer provided on an unmanned forklift when the unmanned forklift places a cargo on a first tier of a multi-tier rack at the stopping position (S1), determining whether or not the correction shifting the traveling center of the unmanned forklift in the rack right and left direction is required at the stopping position using the measured result (S2), and if it is determined that the correction is required at the stopping position, shifting the travel center at the stopping position when the unmanned forklift places the cargo on the second or higher tier of the multi-tier rack at the stopping position (S4).SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present application relates to a method and system for dealing with a slope of the floor surface at the stopping position of an unmanned forklift when placing loads on a multi-tiered rack. [Background technology]

[0002] An unmanned forklift is equipped with an optical sensor such as LiDAR, and by measuring the distance to surrounding objects, it identifies its own position and the positional relationship between itself and the cargo (pallet), and thereby travels and handles cargo automatically. For example, an unmanned forklift travels along a predetermined travel route, stops in front of a multi-tiered rack, and handles cargo on the multi-tiered rack.

[0003] If the floor surface is tilted to the left or right when an unmanned forklift stops to place a load on a multi-tiered rack, there is a risk that the load will come into contact with the rack pillars or with loads that are already placed there.

[0004] In the method disclosed in Patent Document 1, in order to avoid such a risk of contact, whether the floor surface is inclined in the left or right direction is measured in advance.

[0005] Specifically, in this method, a worker first installs a dedicated floor surface measurement jig (see FIG. 2 of Patent Document 1) at the stopping position and measures the inclination angle of the floor surface in the left-right direction of the rack at that stopping position using the inclinometer of the jig. The worker performs similar measurements at all stopping positions within the work area to obtain measurement values ​​for all stopping positions within the work area. Then, from the measurement values, the worker identifies stopping positions where the inclination angle of the floor surface exceeds a predetermined threshold value.

[0006] The method corrects a command value for the unmanned forklift so that the center of travel of the unmanned forklift is shifted left and right at a stop position where the tilt angle exceeds a predetermined threshold. As a result, when the unmanned forklift places a load on the rack at the stop position, the load is placed away from the rack pillars and adjacent loads that are already placed. In this way, it is possible to prevent the loads from coming into contact with each other or with the rack pillars.

[0007] In the method of Patent Document 1, as described above, a worker must actually set up a jig at the stop position and perform measurements. There is a possibility that the position of the jig may shift and the correct inclination angle may not be measured, and errors may occur due to visual judgment. In addition, the worker must perform such measurements for each and every stop position in the work area of ​​the unmanned four-lift truck, which is a heavy burden. It is costly to prepare measurement personnel. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2023-7817 A Summary of the Invention [Problem to be solved by the invention]

[0009] The present application aims to automatically measure the inclination of the floor surface at a stopping position where an unmanned forklift stops to place a load, and to shift the center of travel of the unmanned forklift at that stopping position as necessary. [Means for solving the problem]

[0010] In the present application, a method for dealing with a floor surface inclination at a stopping position where an unmanned forklift stops when placing cargo on a multi-tiered rack is provided, The method comprises: When the unmanned forklift truck places a load on the Nth stage (N is a natural number equal to or greater than 1) of a multi-stage rack at the stopping position, the inclination angle of the rack in the left-right direction of the floor surface at the stopping position is automatically measured using an inclinometer provided on the unmanned forklift truck. Determining whether or not a correction is required to shift the traveling center of the unmanned forklift in the left-right direction of the rack at the stop position using the measurement results; when it is determined that the correction is necessary at the stop position, determining whether the shift direction of the traveling center at the stop position should be in the left or right direction of the rack; When it is determined that the correction is necessary at the stopping position, the center of travel at the stopping position is shifted in the determined shift direction when the unmanned forklift places a load on the N+1th or higher tier of the multi-tier rack at the stopping position.

[0011] The method comprises: When it is determined that the correction is necessary at the stop position, a shift amount of the traveling center at the stop position is determined using the measurement result, If it is determined that the correction is necessary at the stopping position, the center of travel at the stopping position when the unmanned forklift places cargo on the N+1th or higher tier of the multi-tier rack at the stopping position may be shifted by the determined shift amount in the determined shift direction.

[0012] According to the present application, there is further provided a floor surface inclination countermeasure system for countering a floor surface inclination at a stopping position where an unmanned forklift stops when placing a load on a multi-tiered rack, comprising: The system comprises: an inclinometer provided on the unmanned forklift to measure the inclination angle of the floor surface; a measurement execution unit that automatically measures the inclination angle of the rack in a left-right direction at the stop position using the inclinometer when the unmanned forklift places a load on an N-th stage (N is a natural number equal to or greater than 1) of the multi-stage rack at the stop position; a determination unit that determines whether or not a correction is required to shift a traveling center of the unmanned forklift in the left-right direction of the rack at the stop position based on a measurement result of the measurement execution unit; a determination unit that determines a correction value for a command value of the unmanned forklift related to the traveling center at the stop position based on a measurement result of the measurement execution unit when the determination unit determines that the correction is necessary at the stop position; and a correction unit that, when the judgment unit determines that the correction is necessary at the stopping position, corrects the command value to the correction value determined by the decision unit so that when the unmanned forklift places a load on the N+1th tier or higher of the multi-tier rack at the stopping position, the traveling center of the unmanned forklift is shifted in the left-right direction of the rack at the stopping position.

[0013] The inclinometer may be disposed inside the vehicle body so as to measure a lateral inclination angle of the vehicle body of the unmanned forklift, and the determination unit may be configured to output a warning when the measured inclination angle exceeds a threshold value.

[0014] In the above, preferably, N=1 or 2, and more preferably, N=1. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1A is a front view of an exemplary multi-tier rack R, and FIG. 1B is a side view of FIG. 1A. [Diagram 2] FIG. 2A is a schematic side view of an exemplary unmanned forklift, and FIG. 2B is a top view of FIG. 2A. [Diagram 3] FIG. 3 illustrates the risk of luggage contact due to a sloping floor surface. [Figure 4] FIG. 4 illustrates the risk of luggage contact due to a sloping floor surface. [Diagram 5] FIG. 5 is a diagram showing a flow of an exemplary floor surface inclination handling method. [Figure 6]FIG. 6 is a block diagram of an exemplary floor slope management system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, exemplary embodiments of the present application will be described with reference to the drawings. Note that the components shown in the drawings are not necessarily in exact dimensions or proportions, but merely represent their functions or operations.

[0017] [Multi-tier rack] 1A and 1B are schematic diagrams showing an example of a multi-tier rack provided in a work area of ​​an unmanned forklift. This example of a multi-tier rack R (hereinafter simply referred to as rack R) is a four-tier, two-tier rack. That is, in each tier, two areas (hereinafter simply referred to as loading areas) for loading the cargo W are defined in the rack left-right direction Y (hereinafter simply referred to as direction Y). And, in each row, four loading areas are defined in the up-down direction Z (simply referred to as direction Z). Note that direction X is the rack depth direction. And, for each row, stop positions P1 and P2 are defined where the unmanned forklift 1 stops and places the cargo on the rack R. Since multiple such multi-tier racks R are provided in an actual work area, multiple stop positions (P1, P2, ...) are defined. Note that the cargo W shown in the figure is a collective representation of the actual cargo and the pallet on which the cargo is loaded.

[0018] [Unmanned forklift] 2A and 2B show an example of an unmanned forklift 1. The unmanned forklift 1 includes a vehicle body 10, running wheels 11, a traveling device 12, a loading device 13, and forks 14. The traveling device 12 drives the running wheels 11, thereby causing the vehicle body 10 to travel. The loading device 13 is composed of a mast device, a reach device, and the like. The pair of left and right forks 14 are inserted into a pallet of cargo W to support the cargo W. The loading device 13 can move the pair of left and right forks 14 in the up-down direction Fz and in the front-rear direction Fx.

[0019] The unmanned forklift 1 further includes an optical sensor 15 and an operation control unit 16. The optical sensor 15 is a LiDAR or the like, and measures the distance between the unmanned forklift 1 and surrounding objects. The operation control unit 16 is realized, for example, by a CPU executing a program stored in a storage medium. The operation control unit 16 identifies the position of the unmanned forklift 1 and the positional relationship between the unmanned forklift 1 and the cargo W (pallet) based on the measurement by the optical sensor 15, and controls the traveling device 12 and the cargo handling device 13 based on this. The operation control unit 16 enables the unmanned forklift 1 to travel along a travel route within a work area and to perform cargo handling work on a rack R according to a predetermined operation program.

[0020] Specifically, the unmanned forklift 1 travels along a predetermined travel path and stops at a stopping position in front of the rack R so as to face the rack R (i.e. so that the direction X and the direction Fx and the direction Y and the direction Fy are substantially aligned), and can place the cargo W at the stopping position in a loading position of any tier of the rack R. Note that Fig. 1B shows the state in which the unmanned forklift 1 stops at the stopping position P2 (Fig. 1A) with the forks 14 inserted into the pallet of the cargo W and supporting the cargo W with the forks 14, and then starts to move the forks 14 to place the cargo W in the loading position on the second tier of the rack R.

[0021] [Effect of floor inclination] 3 shows an example in which the floor surface is inclined downward to the left at the stop position P1 and inclined downward to the right at the stop position P2. In this state, the z-axis at the stop position P1 is inclined to the left, and the z-axis at the stop position P2 is inclined to the right. When the unmanned forklift 1 actually places a load on the rack R at the stop position P1, the load W is placed to the left of the target loading position Q shown by the dotted line. When the unmanned forklift 1 actually places a load on the rack R at the stop position P2, the load W is placed to the right of the target loading position Q. Therefore, when the unmanned forklift 1 places a load on the rack R at the stop positions P1 and P2, there is a risk that the load W will come into contact with the pillar of the rack R, as shown by the area T.

[0022] 3, in order to avoid contact between the load W and the rack R, the command value for the unmanned forklift 1 is corrected so that the travel center (travel line) of the unmanned forklift 1 is shifted to the right at the stop position P1 (see the corrected travel center C), thereby causing the unmanned forklift 1 to place the load W away from the pillar of the rack R. Then, at the stop position P2, the travel center is shifted to the left.

[0023] 4 shows an example in which the floor surface is inclined downward to the right at the stop position P1 and inclined downward to the left at the stop position P2. In this state, the z-axis at the stop position P1 is inclined to the right, and the z-axis at the stop position P2 is inclined to the left. When the unmanned forklift 1 actually places a load on the rack R at the stop position P1, the load W is placed to the right of the target loading position Q, and when the unmanned forklift 1 actually places a load on the rack R at the stop position P2, the load W is placed to the left of the target loading position Q. Therefore, when the unmanned forklift 1 places a load at the stop position P1 or the stop position P2, there is a risk that the load W will come into contact with the load W already placed in the adjacent loading space, as shown by the area T.

[0024] 4, in order to avoid contact between the loads W, the command value for the unmanned forklift 1 is corrected so that the travel center of the unmanned forklift 1 is shifted to the left at the stop position P1 (see the travel center C after correction), and the unmanned forklift 1 places the load away from the load W already placed at the stop position P2. Then, the travel center is shifted to the right at the stop position P2.

[0025] [Tilt handling method and system] Hereinafter, an exemplary inclination countermeasure method 2 (FIG. 5) (hereinafter simply referred to as method 2) and an inclination countermeasure system 3 (FIG. 6) (hereinafter simply referred to as system 3) for shifting the traveling center in response to such a floor inclination will be described.

[0026] Method 2 includes steps S1 to S4. System 3 includes an inclinometer 30, a measurement execution unit 31, a judgment unit 32, a decision unit 33, and a correction unit 34. The functional units 31 to 34 of system 3 are realized, for example, by a CPU executing a program stored in a storage medium.

[0027] In step S1, when the unmanned forklift 1 places a load on the first level of the rack R at the stopping position, the inclination angle of the floor surface in the direction Y at the stopping position is automatically measured by the inclinometer 30 provided on the unmanned forklift 1.

[0028] To carry out step S1, an inclinometer 30 and a measurement execution unit 31 are used. Specifically, as shown in Fig. 2A, the inclinometer 30 is provided inside the vehicle body 10 and is arranged to measure the inclination angle in the left-right direction Fy of the vehicle body 10. The inclinometer 30 can measure whether the inclination is downward to the right or downward to the left depending on whether the measurement value is positive or negative.

[0029] The measurement execution unit 31 uses the inclinometer 30 to measure the inclination angle in the left-right direction Fy of the body 10 of the unmanned forklift 1 while the unmanned forklift 1 is placing cargo on the first level of the rack R at the stopped position, and thereby measures the inclination angle of the floor surface in the direction Y at the stopped position.

[0030] As described above, the operation control unit 16 uses the optical sensor 15 to identify the position of the unmanned forklift 1 and causes the unmanned forklift 1 to travel. Therefore, the measurement execution unit 31 can recognize that the unmanned forklift 1 is at the stop position. Here, the unmanned forklift 1 stops at the stop position so that its left-right direction Fy matches the rack left-right direction Y, as shown in FIG. 1B. Therefore, the inclination angle indicated by the inclinometer 30 when the unmanned forklift 1 is stopped at the stop position corresponds to the inclination angle of the floor surface in the direction Y at the stop position. Therefore, by utilizing this, the measurement execution unit 31 makes it possible to automatically measure the inclination angle of the floor surface at the stop position.

[0031] In this manner, step S1 causes the unmanned forklift 1 to actually place a load on the first level of the rack R at the stopping position, and at that time, the inclination angle of the floor surface in the direction Y at the stopping position is automatically measured using the inclinometer 30.

[0032] This automatic measurement of the inclination angle of the floor surface in direction Y is performed in the same manner for each stop position (P1, P2...), and the inclination angle of each stop position (P1, P2...) is obtained.

[0033] In step S2, it is determined whether or not a correction for shifting the traveling center at the stopping position is necessary, using the measurement result obtained in step S1.

[0034] To carry out step S2, the determination unit 32 may be used. The determination unit 32 determines whether the tilt angle (its absolute value) of the stop position exceeds a predetermined threshold value (for example, 0.1 degree as in Patent Document 1).

[0035] When the measured tilt angle does not exceed a predetermined threshold value, the determination unit 32 may determine that correction is not necessary at that stop position.

[0036] The determination unit 32 may output a warning when the measured inclination angle exceeds a predetermined threshold. Then, the display device 17 (FIG. 2A) of the unmanned forklift 1 or a display device (not shown) of a worker in the work area may display the warning when the warning is output. This allows the worker to know that the floor surface at the stopping position is inclined beyond the threshold.

[0037] When the tilt angle at a stop position exceeds a predetermined threshold, the determination unit 32 may determine that correction is necessary at that stop position. Also, the determination unit 32 may determine that correction is necessary at each of the stop positions P1 and P2 when the tilt angle at two adjacent stop positions P1 and P2 exceeds a threshold and a predetermined tilt pattern (for example, a pattern in which the z-axis of the two stop positions P1 and P2 forms an inverted V shape as shown in FIG. 4) is detected at the two stop positions P1 and P2, as in Patent Document 1, for example.

[0038] A determination is made as to whether or not correction is necessary for all stop positions (P1, P2,...). The method of determination in step S2 and by the determination unit 32 is not limited to the above example, and various methods may be adopted. Hereinafter, a stop position for which it is determined that correction of the traveling center is necessary may be referred to as a correction-requiring position.

[0039] In step S3, if it is determined in step S2 that correction of the traveling center is necessary at the stopping position, it is determined in which direction (to the left or right) in the direction Y the traveling center of the unmanned forklift 1 at the stopping position should be shifted.

[0040] As described above, the inclinometer 30 also indicates the direction of inclination. Therefore, in step S3, using the measurement result by the measurement execution unit 31 in step S1, it is determined that the center of travel is to be shifted to the right when the floor surface slopes downward to the left at the position requiring correction, and that the center of travel is to be moved to the left when the floor surface slopes downward to the right.

[0041] Also, step S3 determines the shift amount of the traveling center at the correction required position based on the measurement result. Since the inclination angle of the floor surface is larger, the inclination of the z-axis is larger, step S3 may increase the shift amount as the inclination angle (its absolute value) is larger. Also, the deviation of the actual placement position of the luggage W from the target placement position Q tends to increase as the number of steps of the rack R increases. Therefore, step S3 may increase the shift amount of the traveling center at the same correction required position as the number of steps of the rack R increases. For example, step S3 may set the shift amount of the second step of the rack R to 10 mm to the right, the shift amount of the third step to 20 mm to the right, and the shift amount of the fourth step to 30 mm to the right at the same correction required position. Instead, step S3 may determine the shift amount for the second step or higher to be 20 mm to the right regardless of the step at the same correction required position. Step S3 may determine the amount of shift required to avoid collision of packages using structural information of the rack in addition to the measurement results.

[0042] The system 3 uses the determination unit 33 to carry out the above-mentioned step S3. The determination unit 33 uses the measurement result by the measurement execution unit 31 to determine, by calculation, a correction value for the command value of the unmanned forklift 1 related to the traveling center, which corresponds to the shift amount and the shift direction.

[0043] The same process is performed for all positions requiring correction. The method of determining the shift amount, shift direction, and correction value by step S3 and the determination unit 33 is not limited to the above example, and various methods may be adopted.

[0044] In step S4, if it is determined that a correction is required to shift the traveling center at the stopping position, the traveling center at the stopping position when the unmanned forklift 1 places a load on the second or higher level of the rack R at the stopping position is shifted in the direction and by the amount determined in step S3.

[0045] The correction unit 34 is used to carry out step S4. The correction unit 34 corrects the command value of the unmanned forklift when placing a load on the second or higher tier at the correction required position to the correction value determined by the determination unit 33. As a result, the operation control unit 16 of the unmanned forklift 1 controls the traveling device 12 with the corrected command value to travel the unmanned forklift 1. Therefore, when the unmanned forklift 1 stops at the correction required position to place a load on the second or higher tier, the traveling center is shifted in the shift direction and by the shift amount determined in step S3 at the correction required position (see the corrected traveling center C in Figures 3 and 4).

[0046] For example, in steps S1 to S3, it is determined that the stop position P1 is not a position requiring correction, and the stop position P2 is a position requiring correction, and the shift amount and shift direction (correction value for the command value at the stop position) at the stop position P2 are determined. In this case, in method 2, the traveling center at the stop position P1 is not shifted when the unmanned forklift 1 places a load on the second or higher level at the stop position P1. In other words, in method 2, the traveling center is not corrected.

[0047] On the other hand, in method 2, the traveling center at the stop position P2 when the unmanned forklift 1 stops at the stop position P2 and places the cargo on the second, third, and fourth tiers is shifted to avoid the risk of contact with the cargo W. In this way, correction is made to shift the traveling center only for the second and higher tiers of the rack R as necessary.

[0048] As described above, in this embodiment, the inclinometer 30 provided on the unmanned forklift 1 automatically measures the inclination angle of the floor surface in the direction Y at the stopping position while the unmanned forklift 1 is placing a load on the first level of the rack R at the stopping position, and only when placing a load on the second or higher level of the rack R, the center of travel at the stopping position is shifted to the left or right as necessary to avoid contact between the loads W or between the loads W and the rack R.

[0049] In this way, the embodiment eliminates the need for a dedicated measuring jig that imitates the wheelbase of an unmanned forklift as disclosed in Patent Document 1, and the need for manual measurement using the jig. When a person uses a jig for measurement, the position of the jig is often misaligned, and the measurement value often does not reflect the accurate inclination angle of the floor surface because of visual judgment. In contrast, the embodiment automatically measures the inclination angle of the floor surface while the unmanned forklift 1 that actually works in the work area is working at the stopped position, so the measurement value is accurate. Furthermore, the embodiment also reduces costs by eliminating the need for measurement personnel.

[0050] In addition, the inclination angle of the floor surface in the direction Y at the stopping position during the loading operation on a level where the risk of contact with the rack R or other cargo W is relatively low, for example the second level of the rack R, can be measured, not limited to the first level as in the embodiment, and the center of travel when loading cargo can be shifted only for the third level or higher levels at that stopping position as necessary.

[0051] The functional units 31 to 34 of the system 3 may be provided in the unmanned forklift 1, or some or all of them may be provided in a device capable of wirelessly communicating with the unmanned forklift 1 (for example, a server device that manages a work area). [Explanation of symbols]

[0052] 1. Unmanned forklift 10. Body 2. How to deal with tilt 3. Tilt response system 30 Inclinometer 31 Measurement Execution Department 32 Judgment section 33 Decision Section 34 Correction section R Multi-tier rack W Luggage Y rack left / right direction Fy Left and right direction of unmanned forklift

Claims

1. A method for dealing with a floor surface inclination at a stopping position where an unmanned forklift stops when placing a load on a multi-tiered rack, comprising: When the unmanned forklift truck places a load on the Nth stage (N is a natural number equal to or greater than 1) of a multi-stage rack at the stopping position, the inclination angle of the floor surface in the left-right direction of the rack at the stopping position is automatically measured using an inclinometer provided on the unmanned forklift truck. Determining whether or not a correction is required to shift the traveling center of the unmanned forklift in the left-right direction of the rack at the stop position using the measurement results; when it is determined that the correction is necessary at the stop position, determining whether the shift direction of the traveling center at the stop position should be in the left or right direction of the rack; When it is determined that the correction is necessary at the stop position, the traveling center at the stop position is shifted in the determined shift direction when the unmanned forklift places an article on an N+1th or higher tier of the multi-tier rack at the stop position. How to deal with floor inclination.

2. When it is determined that the correction is necessary at the stop position, a shift amount of the traveling center at the stop position is determined using the measurement result, When it is determined that the correction is necessary at the stop position, the traveling center at the stop position when the unmanned forklift places an article on the N+1th or higher stage of the multi-stage rack at the stop position is shifted by the determined shift amount in the determined shift direction. The method for dealing with a sloped floor surface according to claim 1.

3. N is 1 or 2; The method for dealing with a sloped floor surface according to claim 1.

4. N is 1; The method for dealing with a sloped floor surface according to claim 1.

5. A floor surface inclination countermeasure system for countering a floor surface inclination at a stopping position where an unmanned forklift stops when placing a load on a multi-tiered rack, comprising: an inclinometer provided on the unmanned forklift to measure the inclination angle of the floor surface; a measurement execution unit that automatically measures the inclination angle of the rack in a left-right direction at the stop position using the inclinometer when the unmanned forklift places an article on an N-th stage (N is a natural number equal to or greater than 1) of the multi-stage rack at the stop position; a determination unit that determines whether or not a correction is required to shift a traveling center of the unmanned forklift in the left-right direction of the rack at the stop position based on a measurement result of the measurement execution unit; a determination unit that determines a correction value for a command value of the unmanned forklift related to the traveling center at the stop position based on a measurement result of the measurement execution unit when the determination unit determines that the correction is necessary at the stop position; a correction unit that corrects the command value to the correction value determined by the decision unit when the determination unit determines that the correction is necessary at the stop position, so that when the unmanned forklift places a load on an N+1th or higher tier of the multi-tier rack at the stop position, the traveling center of the unmanned forklift is shifted in the left-right direction of the rack at the stop position. Floor inclination control system.

6. The inclinometer is disposed inside the vehicle body so as to measure the inclination angle in the left-right direction of the vehicle body of the unmanned forklift. The floor surface inclination countermeasure system according to claim 5.

7. The determination unit is configured to output a warning when the measured tilt angle exceeds a threshold value. The floor surface inclination countermeasure system according to claim 5.

8. N is 1 or 2; The floor surface inclination countermeasure system according to claim 5.

9. N is 1; The floor surface inclination countermeasure system according to claim 5.

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