discharge control device

Abstract

Unloading control device (1, 1A) for loading a pallet (11) held by forks (12) of a forklift (2) onto a loading section in order to remove the forks (12) from the pallet (11), wherein the unloading control device (1, 1A) comprises: a pallet detection unit (31) configured to detect the pallet (11) held by the forks (12) and to obtain detection data of the pallet (11); a tilt angle detector (21) configured to detect a tilt angle of the forks (12); a lowering control unit (33) configured to control a lifting cylinder (23) of the forklift (2) so that the forks (12) holding the pallet (11) are lowered towards the loading section; a change amount estimation unit (39) configured to estimate a change amount of a position of the pallet (11) with respect to the forks (12) based on the pallet (11) detection data obtained from the pallet detection unit (31) and the tilt angle of the forks (12) detected by the tilt angle detector (21) when the forks (12) holding the pallet (11) are lowered; a determination unit (35) configured to determine whether the pallet (11) held by the forks (12) rests on an upper surface of the loading section or not, based on the amount of change in the position of the pallet (11) relative to the forks (12) estimated by the change amount estimation unit (39); a tilt control unit (36) configured to control a tilt cylinder of the forklift (2) such that the forks (12) tilt in a direction approaching parallel to a main surface of the pallet (11) when the determination unit (35) determines that the pallet (11) held by the forks (12) is resting against an upper surface of the loading section; and a retraction control unit (38) configured to control the forklift (2) to remove the forks (12) from the pallet (11) according to the tilt angle of the forks (12) detected by the tilt angle detector (21) after the forks (12) approach parallel to the main surface of the pallet (11). wherein the palette acquisition unit (31) acquires point cloud data of the palette (11) in three dimensions, and When the forks (12) holding the pallet (11) are lowered, the change amount estimation unit (39) compares the most recent point cloud data of the pallet (11) obtained from the pallet acquisition unit (31) with reference point cloud data of the pallet (11) obtained from the pallet acquisition unit (31) prior to the most recent point cloud data in order to estimate a change amount of a position of the pallet (11) with respect to the forks (12).

Description

TECHNICAL AREA

[0001] The present invention relates to a discharge control device. BACKGROUND

[0002] For example, Japanese patent JP 6 436 553 B1 describes a technique for removing a load by lifting a fork section of a forklift in a state where the fork section is inserted into a pallet, then transporting the load by the forklift and unloading the load onto a truck bed for transport. Furthermore, SE 2350058 A1 discloses a forklift having a control device configured to execute a stop process to halt the lowering of the forks by the lifting device when the detection sensor is disconnected from the first opposite surface while the forks are being lowered by the lifting device during the lowering process, and a forward tilting process that is executed after the stop process, wherein the forward tilting process controls the tilting device so that the forks are tilted forward until the tilt angle reaches a limit.and a reset process for sequentially acquiring values ​​of the tilt angle, calculated based on a signal from the tilt sensor during the execution of the forward tilting process, wherein the reset process controls the tilt direction such that the fork is tilted backwards, so that the insertion section or the sensing sensor is separated from the first opposite surface when the value of the tilt angle no longer changes before the tilt angle reaches the limit, wherein the reset process is not executed when the tilt angle reaches the limit. JP 2017-19595 A discloses a method for picking up a load in an unmanned forklift, wherein a laser sensor measures the distance to holes into which forks are inserted, and the tilt of the holes relative to the approach direction of the forks is detected based on the height of the laser sensor.to then determine, based on the detected inclinations, whether or not the fork inclinations should be changed. Furthermore, JP 2005-8367A describes a forklift truck moving towards a pallet to insert the forks into the pallet's fork-receiving opening for loading. The presence of a forward / backward tilt of the forks relative to the insertion direction into the fork-receiving opening and the presence of a vertical displacement of the forks relative to the fork-receiving opening are detected based on the results of sensing by a variety of sensors located at the tip and base of the forks. The operating mode for correcting the tilt and vertical displacement is set, and the forks are raised while tilting forward / backward to position the tip and base of the forks in a near-central area in the vertical direction of the fork-receiving opening. SUMMARY

[0003] For example, the loading platform of a truck equipped with suspension may be inclined in a direction suitable for a forklift. When unloading onto a loading section such as a platform with such an incline, the forks may easily catch on the inner wall of the pallet as they are removed.

[0004] It is an object of the present invention to provide an unloading control device that is able to gently remove the forks from a pallet when a load is unloaded from a loading section inclined in a direction of inclination.

[0005] The problem is solved according to the invention by a discharge control device according to claim 1. Further features and advantageous embodiments are shown in the dependent claims.

[0006] (1) One aspect of the present invention is an unloading control device for loading a pallet held by the forks of a forklift truck onto a loading section in order to remove the forks from the pallet, wherein the unloading control device comprises a pallet detection unit configured to detect the pallet held by the forks and to obtain detection data of the pallet, a tilt angle detector configured to detect a tilt angle of the forks, a lowering control unit configured to control a lifting cylinder of the forklift truck so that the forks holding the pallet are lowered towards the loading section, and a change amount estimation unit configured toto estimate the amount of change in the pallet's attitude relative to the forks based on the pallet detection data obtained from the pallet detection unit and the fork tilt angle detected by the tilt angle detector when the forks holding the pallet are lowered; a determination unit configured to determine whether the pallet held by the forks is resting against an upper surface of the loading section, based on the amount of change in the pallet's attitude relative to the forks estimated by the change estimation unit; a tilt control unit configured to control a tilt cylinder of the forklift so that the forks tilt in a direction approaching parallel to a main surface of the pallet when the determination unit determines that the pallet held by the forks is resting against an upper surface of the loading section.and a retraction control unit configured to control the forklift to remove the forks from the pallet according to the tilt angle of the forks detected by the tilt angle detector, after the forks approach parallel to the main surface of the pallet.

[0007] In such an unloading control device, when the load is unloaded from the loading section, the lifting cylinder is controlled so that the forks holding the pallet lower towards the loading section. At this point, the pallet held by the forks is detected, the angle of inclination of the forks is recorded, and the change in the pallet's position relative to the forks is estimated. Subsequently, based on this change in the pallet's position relative to the forks, it is determined whether the pallet held by the forks is resting on the upper surface of the loading section or not. If the pallet is resting on the upper surface of the loading section, which is inclined in the direction of the slope, the pallet's position relative to the forks changes. Therefore, the change in the pallet's position relative to the forks indicates whether the pallet is resting on the upper surface of the loading section, which is inclined in the direction of the slope.Once it is determined that the pallet held by the forks rests against the upper surface of the loading section, the tilt cylinder is controlled so that the forks tilt in a direction approaching the main surface of the pallet. The forklift is then controlled so that the forks are removed from the pallet according to the angle of the fork tilt. When the pallet rests against the upper surface of the tilted loading section, the pallet tilts according to the incline of the loading section. However, because the forks tilt in a direction approaching the main surface of the pallet, they are prevented from contacting the inner wall of the pallet. This ensures that the forks are gently removed from the pallet when a load is unloaded from the tilted loading section.

[0008] The pallet sensing unit acquires point cloud data of the pallet in three dimensions, and when the forks holding the pallet are lowered, the change amount estimation unit compares the most recent point cloud data of the pallet acquired by the pallet sensing unit with reference point cloud data of the pallet acquired prior to the most recent point cloud data by the pallet sensing unit to estimate a change amount of a pallet attitude relative to the forks.

[0009] In such a configuration, when the forks holding the pallet are lowered in a state where the tilt angle of the forks is constant, the point cloud data of the pallet are periodically referenced three-dimensionally, and the latest point cloud data of the pallet are compared with the reference point cloud data of the pallet, making it easy to estimate the amount of change in the position of the pallet with respect to the forks.

[0010] Furthermore, the unloading control unit may also include a height position detector configured to obtain a height position of the forks, wherein the change amount estimation unit can estimate a change in the height position and attitude of the pallet relative to the forks based on pallet detection data acquired by the pallet detection unit, wherein the height position of the forks is detected by the height position detector, and the tilt angle of the forks is detected by the tilt angle detector when the forks holding the pallet are lowered, and the determination unit can determine whether the pallet held by the forks is resting on an upper surface of the loading section based on the change in the height position and attitude of the pallet relative to the forks estimated by the change amount estimation unit.

[0011] In such a configuration, the position of the pallet and the change in its attitude relative to the forks determine whether the pallet held by the forks rests on the upper surface of the loading section. If the pallet rests on the upper surface of the inclined loading section, its position and attitude relative to the forks change. If the pallet rests on the non-inclined upper surface of the loading section, its position changes, but its attitude relative to the forks does not. Therefore, if the pallet rests on the upper surface of the inclined loading section, the forks are inclined in a direction closer to the main surface of the pallet, as the pallet is tilted according to the incline of the loading section.If, on the other hand, the pallet rests on the upper surface of the non-inclined loading section, the forks are not necessarily inclined.

[0012] Furthermore, the determination unit can determine that the pallet held by the forks rests on the upper surface of the loading section if the change in the pallet's position relative to the forks is greater than a first threshold, and determine that the pallet held by the forks rests on the upper surface of the loading section if the change in the pallet's position relative to the forks is equal to or less than the first threshold and a change in the pallet's height position relative to the forks is equal to or greater than a second threshold, and the tilt control unit can control the tilt cylinder to tilt the forks in a direction approaching parallel to a principal surface of the pallet if the change in the pallet's position relative to the forks is greater than the first threshold.

[0013] In such a configuration, if the change in the pallet's position relative to the forks is greater than the first threshold, the pallet is determined to rest on the upper surface of the inclined loading section, and the forks are determined to tilt in a direction approaching the main surface of the pallet. If the change in the pallet's position relative to the forks is equal to or less than the first threshold, and the change in the pallet's height relative to the forks is equal to or greater than the second threshold, the pallet is determined to rest on the upper, non-inclined surface of the loading section, and the forks are determined not to tilt.

[0014] Furthermore, the unloading control device may also include a pallet holding detector configured to detect whether the pallet is held by the forks or not, and the determination unit may determine whether the pallet held by the forks is resting against an upper surface of the loading part or not, based on the amount of change in the pallet's holding position relative to the forks, estimated by the amount of change estimation unit, and a detection result from the pallet holding detector.

[0015] In this configuration, whether the pallet held by the forks rests against the upper surface of the loading section is determined based on the change in the pallet's position relative to the forks and the detection result of whether the pallet is in a state where it is held by the forks. If the pallet rests against the upper surface of the loading section, which is inclined in the direction of the incline, the pallet's position relative to the forks changes to a state where the pallet is held by the forks. If the pallet rests against the upper surface of the loading section, which is not inclined, the pallet is not held by the forks, and the pallet's position relative to the forks does not change.If the pallet rests on the upper surface of the loading section, which is inclined in the direction of the slope, the forks will therefore be inclined in a direction that approximates the main surface of the pallet, since the pallet is inclined according to the slope of the loading section. If the pallet rests on the upper surface of the loading section, which is not inclined, the forks will not necessarily be inclined.

[0016] Furthermore, the determination unit can determine that the pallet held by the forks rests on the upper surface of the loading section if the change in the pallet's position relative to the forks is greater than a threshold, and determine that the pallet held by the forks rests on the upper surface of the loading section if the change in the pallet's position relative to the forks is equal to or less than the threshold and the pallet position detector detects that the pallet is not held by the forks, and the tilt control unit can control the tilt cylinder so that the forks tilt in a direction approximating a principal surface of the pallet if the change in the pallet's position relative to the forks is greater than the threshold.

[0017] If, in such a configuration, the change in the pallet's position relative to the forks exceeds the threshold, the pallet is determined to rest on the upper surface of the inclined loading section, and the forks are determined to tilt in a direction approximately parallel to the main surface of the pallet. If the change in the pallet's position relative to the forks is equal to or less than the threshold, and the pallet is not held by the forks, the pallet is determined to rest on the upper, non-inclined surface of the loading section, and the forks are not determined to tilt. Advantageous effects of the invention

[0018] According to the present invention, it is possible to gently remove the forks from a pallet when unloading cargo from a loading section inclined in a direction of inclination. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a block diagram illustrating a configuration of a discharge control device according to a first embodiment of the present invention; Fig. 2 is a perspective view that considers a state in which a forklift truck, equipped with the in Fig. 1. The unloading control device shown in the illustration is mounted and performs the unloading of cargo from the loading platform of a truck; Fig. Figure 3 is a representation illustrating an example of point cloud data generated by a [missing information - likely a specific device or system]. Fig. 1 illustrated RGBD camera together with a loading handling device of a forklift truck; Fig. 4 is a flowchart that shows the process of handling the discharge control, which is carried out by a in Fig. 1 illustrated control to be executed; Fig. 5 is a flowchart that details step S114 in Fig. 4 illustrates; Fig. Figures 6A to 6C are side views illustrating a process in which the forklift lowers the pallet onto a loading surface that is not inclined in the direction of the slope and removes the forks from the pallet; Fig. Figures 7A to 7C are side views illustrating the lowering of the pallet onto a loading platform that is inclined to lower the forklift towards the front; Fig. Figure 8 is a cross-sectional view illustrating the process of removing the forks from the pallet placed on the loading platform, as described in the Fig. 7A to 7C is shown; Fig. Figures 9A to 9C are side views illustrating the lowering of the pallet onto a loading platform that is inclined so that the forklift is lowered towards the rear; Fig. Figure 10 is a block diagram illustrating a configuration of a discharge control device according to a second embodiment of the present invention; and Fig. 11 is a flowchart that shows the process of handling the discharge control, which is carried out by a in Fig. The control shown in the 10 illustrations is to be executed. DETAILED DESCRIPTION

[0019] An embodiment of the present disclosure is described in detail below with reference to the drawings. In the drawings, identical or equivalent elements are designated with the same reference numerals, and repeated descriptions are omitted.

[0020] Fig. Figure 1 is a block diagram illustrating a configuration of a discharge control device according to a first embodiment of the present invention. Fig. 1 is an unloading control device 1 according to the present embodiment mounted on a forklift 2. The forklift 2 is, as in Fig. Figure 2 illustrates a reach truck. The forklift truck 2 comprises a drive unit 3 and a loading handling unit 4.

[0021] The driving device 3 comprises a vehicle body 5, a pair of left and right legs 6 arranged below the vehicle body 5, and a front, rear, left and right wheel 7.

[0022] The loading handling device 4 comprises a pair of left and right outer masts 8, each movably arranged between the gripping legs 6 in a front-back direction, an inner mast 9, which is arranged inside the outer mast 8 in a left-right direction (vehicle width direction) so that it can be raised and lowered relative to the outer mast 8, and a pair of left and right forks 12, which are attached to the inner mast 9 so that they can be raised and lowered via a lifting bracket 10 and hold a pallet 11.

[0023] The forks 12 are L-shaped. The forks 12 comprise a connecting section 17, which is rotatably connected to the lifting bracket 10, and a tine section 18, which extends forward from a lower end section of the connecting section 17 (see Fig. 6A to 6C and the like).

[0024] Pallet 11 is, for example, a flat pallet made of plastic or wood. Pallet 11 has a square or substantially square shape in plan view. A load M is placed on pallet 11. Pallet 11 is provided with a fork hole 11a into which the tine section 18 of the forks 12 is inserted.

[0025] The unloading control device 1 is a device for unloading cargo onto a loading platform 16 of a truck 15 by means of the automatic operation of the forklift 2. The unloading control device 1 unloads the cargo onto the loading platform 16 on the side of the truck 15. Specifically, the unloading control device 1 loads the pallet 11, held by the forks 12, onto the loading platform 16 and removes the forks 12 from the pallet 11. The loading platform 16 of the truck 15 is a loading section on which the pallet 11 is loaded.

[0026] On truck 15, the loading platform 16 can be inclined in the direction of the vehicle's width, since the height of the loading platform 16 differs depending on the function of the left and right suspension (not illustrated). In this case, when unloading onto the loading platform 16 of truck 15, the loading platform 16 is inclined in the direction of the forklift 2's inclination (see Fig. 7A to 7C and Fig. 9A to 9C).

[0027] Back to Fig. 1: The unloading control device 1 comprises an RGBD camera 20, a tilt angle sensor 21, a lift sensor 22, a lift cylinder 23, a tilt cylinder 24, a gripping cylinder 25, a motion amount sensor 29 and a controller 30.

[0028] The RGBD camera 20 is a camera that captures an image of the pallet 11 held by the forks 12. The RGBD camera 20 records the pallet 11 held by the forks 12 together with the load M in a state in which the load M is placed on the pallet 11. The RGBD camera 20 is mounted on an upper section of the inner mast 9 (see Fig. 2) The position where the RGBD camera 20 is mounted is not limited to the inner mast 9, but can also be on the outer mast 8, on the vehicle body 5 or similar.

[0029] The RGBD camera 20 is a type of depth camera that can capture color information (RGB) and depth information (D). As in Fig. As illustrated in Figure 3, the RGBD camera 20 measures a distance to a surrounding object and acquires a point cloud P of the object in three dimensions. The point cloud P is a group of reflection points of the light emitted by the RGBD camera 20.

[0030] The tilt angle sensor 21 is a sensor that detects the tilt angle (tipping angle) of the forks 12 relative to the inner mast 9. The tilt angle sensor 21 is a tilt angle detector that detects the tilt angle of the forks 12. The tilt angle sensor 21 is, for example, mounted on the lifting bracket 10.

[0031] The lift sensor 22 is a sensor that detects the height from the ground to the tine section 18 of the forks 12. The lift sensor 22 acts as a height position detector, recording the height position of the forks 12. The lift sensor 22 is, for example, mounted on the lifting bracket 10.

[0032] The lifting cylinder 23 is a hydraulic cylinder that raises and lowers the forks 12. The tilting cylinder 24 is a hydraulic cylinder that tilts the forks 12 forward and backward. The thrust cylinder 25 is a hydraulic cylinder that moves the forks 12 forward and backward by moving the outer mast 8 forward and backward.

[0033] The movement amount sensor 29 is a sensor that detects a movement amount (feed and retraction amount) of the forks 12 in the front-back direction through the gripping cylinder 25.

[0034] The controller 30 consists of a CPU, RAM, ROM, an input / output interface, and the like. The controller 30 includes a point cloud extraction unit 31, a reference point cloud data storage unit 32, a lowering control unit 33, a unit for determining the amount of change in position / posture 34, a unit for determining the pallet stop 35, a tilt control unit 36, a lifting control unit 37, and a lowering control unit 38.

[0035] The point cloud extraction unit 31 extracts as point cloud data only the point cloud P that is located in a point cloud extraction region Ap (see Fig. 3) is present, from the three-dimensional point cloud P acquired by the RGBD camera 20. The point cloud extraction region Ap is a rectangular, parallelepipedic region comprising a point cloud P corresponding to palette 11 and a point cloud P corresponding to an object near palette 11. The object near palette 11 comprises the cargo M located on palette 11.

[0036] The point cloud extraction unit 31, in conjunction with the RGBD camera 20, configures a pallet detection unit that detects the pallet 11 held by the forks 12 and acquires data from the pallet 11. The point cloud extraction unit 31 acquires the point cloud data of the pallet 11 three-dimensionally as data from the pallet 11.

[0037] The reference point cloud data storage unit 32 stores the point cloud data comprising the point cloud P corresponding to palette 11, extracted by the point cloud extraction unit 31 at the beginning of unloading, in an internal memory (not illustrated) as reference point cloud data.

[0038] The lowering control unit 33 controls the lifting cylinder 23 to lower the forks 12, which hold the pallet 11, towards the loading platform 16 of the truck 15.

[0039] When the forks 12 holding the pallet 11 are lowered, the estimation unit 34 estimates the amount of change in the position and attitude of the pallet 11 relative to the forks 12 based on the data extracted by the point cloud extraction unit 31, the height position of the forks 12 detected by the lifting sensor 22, and the tilt angle of the forks 12 detected by the tilt angle sensor 21.

[0040] The height position of the pallet 11 with respect to the forks 12 is a relative height position of the pallet 11 with respect to the tine section 18 of the forks 12. In particular, the height position of the pallet 11 with respect to the forks 12 is the height position of the upper edge of the opening of the fork hole 11a of the pallet 11 with respect to the tine section 18 of the forks 12. The attitude of the pallet 11 with respect to the forks 12 is a relative attitude of the pallet 11 with respect to the tine section 18 of the forks 12. In particular, the attitude of the pallet 11 with respect to the forks 12 is an angle of inclination of the pallet 11 with respect to the tine section 18 of the forks 12.

[0041] The change amount estimation unit 34 represents a change amount estimation unit that estimates the change in the position of the pallet 11 with respect to the forks 12 on the basis of the pallet 11 acquisition data obtained from the point cloud extraction unit 31 and the tilt angle of the forks 12 detected by the tilt angle sensor 21 when the forks 12 holding the pallet 11 are lowered.

[0042] When the forks 12 holding the pallet 11 are lowered, the position / location change estimation unit 34 compares the most recent point cloud data of pallet 11 obtained by the point cloud extraction unit 31 with the reference point cloud data of pallet 11 obtained before the most recent point cloud data obtained by the point cloud extraction unit 31 and estimates the change in the position of pallet 11 relative to the forks 12. The reference point cloud data of pallet 11 obtained before the most recent point cloud data by the point cloud extraction unit 31 is the reference point cloud data stored in the reference point cloud data storage unit 32.

[0043] The determination unit 35 for the pallet stop determines whether the pallet 11 held by the forks 12 is against an upper surface 16a (see Fig. 6A to 9C) of the load 16 of the truck 15 rests on or not rests on the pallet 11 in relation to the forks 12, as estimated by the estimating unit 34 for the change in position.

[0044] If the change in the position of the pallet 11 relative to the forks 12 is greater than the angle threshold (first threshold), the pallet stop unit 35 determines that the pallet 11 held by the forks 12 rests on the upper surface 16a of the load 16. If the change in the position of the pallet 11 relative to the forks 12 is equal to or less than the angle threshold and the change in the height position of the pallet 11 relative to the forks 12 is equal to or greater than the height threshold (second threshold), the pallet stop unit 35 determines that the pallet 11 held by the forks 12 rests on the upper surface 16a of the load 16.

[0045] The pallet stop determination unit 35 represents a determination unit that determines whether the pallet 11 held by the forks 12 rests on the upper surface 16a of the load 16 or not, on the basis of the change amount in the holding of the pallet 11 in relation to the forks 12 estimated by a change amount estimation unit.

[0046] When the pallet detection unit 35 determines that the pallet 11 held by the forks 12 is resting on the upper surface 16a of the load 16, the tilt control unit 36 ​​controls the tilt cylinder 24 so that the forks 12 tilt in a direction parallel to a main surface 11b of the pallet 11, based on the detected value from the tilt angle sensor 21. The main surface 11b of the pallet 11 consists of two opposing support surfaces on which the load M is placed on the pallet 11.

[0047] If the amount of change in the attitude of the pallet 11 with respect to the forks 12 is greater than the threshold value for the angle, the tilt control unit 36 ​​controls the tilt cylinder 24 so that the forks 12 tilt in a direction that approaches a main surface 11b of the pallet 11 on the basis of the detected value of the tilt angle sensor 21.

[0048] When the pallet detection unit 35 determines that the pallet 11 held by the forks 12 is resting on the upper surface 16a of the load 16, the control unit 37 controls the lifting cylinder 23 so that it raises and lowers the forks 12 in a direction in which they do not touch the inner wall surface of the pallet 11, based on the detected value of the lift sensor 22.

[0049] After the processing by the tilt control unit 36 ​​and the lift control unit 37 has been completed, the retraction control unit 38 controls the lift cylinder 25 to remove the forks 12 from the pallet 11 according to the tilt angle of the forks 12 detected by the tilt angle sensor 21 and the amount of movement of the forks 12 in the front-back direction detected by the movement amount sensor 29. After the forks 12 have approached the main surface 11b of the pallet 11 parallel to each other, the retraction control unit 38 controls the gripping cylinder 25 to remove the forks 12 from the pallet 11 according to the tilt angle of the forks 12 and the amount of movement of the forks 12 in the front-back direction.

[0050] Fig. Figure 4 is a flowchart that specifies the process for controlling the unloading, which is to be executed by the controller 30. This process is executed when the start of unloading is commanded in a state where the pallet 11 is held by the forks 12.

[0051] At the start of the execution of the present process, the forks 12 are in a position higher than the loading platform 16 of the truck 15, in a state in which the forks 12 hold the pallet 11 so that it extends in a horizontal direction (see Fig. 6A and the like). Furthermore, the forks 12 are in a state where the pallet 11 is held by the forks 12, in contact with the upper inner wall surface of the pallet 11 (see Fig. 6A and similar).

[0052] In Fig. 4. The controller 30 first obtains initial point cloud data from the RGBD camera 20 (step S101). Then, the controller 30 extracts a point cloud that is located in the point cloud extraction region Ap (see Fig. 3) exists, based on the initial point cloud data of the RGBD camera 20 (step S102). Subsequently, the controller 30 stores the point cloud data comprising the point cloud present in the point cloud extraction region Ap in its internal memory (not illustrated) as reference point cloud data (step S103).

[0053] The controller 30 then controls the lifting cylinder 23 so that it begins lowering the forks 12 (step S104). Next, the controller 30 obtains point cloud data from the RGBD camera 20 (step S105). Then, the controller 30 extracts the point cloud present in the point cloud extraction region Ap based on the point cloud data from the RGBD camera 20 and determines the point cloud data that includes the point cloud present in the point cloud extraction region Ap as the most recent point cloud data (step S106).

[0054] The controller 30 then estimates the changes in the height position and tilt angle of the pallet 11 relative to the forks 12 based on the latest point cloud data determined in step S106, the reference point cloud data stored in step S103, and the recorded values ​​from the tilt angle sensor 21 and the lift sensor 22 (step S107). The controller 30 extracts the difference between the latest point cloud data and the reference point cloud data to estimate the changes in the height position and tilt angle of the pallet 11 relative to the forks 12.

[0055] In a state where the pallet 11 is normally held by the forks 12, the tine section 18 of the forks 12 comes into contact with the upper inner wall surface of the pallet 11 along the front-back direction, so that the inclination angle of the pallet 11 with respect to the forks 12 is 0 degrees.

[0056] Specifically, the controller 30 estimates the height position and tilt angle of the pallet 11 relative to the forks 12 from the data of the reference point cloud and the latest point cloud data using a three-dimensional point cloud registration method, such as Iterative Closest Point (ICP). ICP is performed to align the measurement point cloud and the reference point cloud by minimizing the distance between them; that is, the reference point cloud is shifted and rotated accordingly. At this point, the reference point cloud data is shifted and rotated using the tilt angle of the forks 12 detected by the tilt angle sensor 21 and the height position of the forks 12 detected by the lift sensor 22. This improves the accuracy of the estimation of the height position and tilt angle of the pallet 11 relative to the forks 12 and the computation speed of the registration.

[0057] The controller 30 then determines whether the change in the tilt angle of the pallet 11 relative to the forks 12, estimated in step S107, is equal to or less than a predetermined angle threshold (step S108). If it is determined that the change in the tilt angle of the pallet 11 relative to the forks 12 is equal to or less than the angle threshold, the controller 30 determines whether the change in the height position of the pallet 11 relative to the forks 12, estimated in step S107, is equal to or greater than a predetermined height threshold (step S109).

[0058] If the controller 30 determines that the change in the height position of the pallet 11 relative to the forks 12 is not equal to or greater than the threshold, step S104 described above is executed again. If the controller 30 determines that the change in the position of the pallet 11 relative to the forks 12 is equal to or greater than the threshold, it controls the lifting cylinder 23 to stop the lowering of the forks 12 (step S110).

[0059] If the control unit 30 determines that the change in the tilt angle of the pallet 11 with respect to the forks 12 is not equal to or less than the threshold value of the angle in step S108, it controls the lifting cylinder 23 to stop the lowering of the forks 12 (step S111).

[0060] Then, based on the detected value from the tilt angle sensor 21, the controller 30 controls the tilt cylinder 24 so that the forks 12 tilt until the tine section 18 of the forks 12 becomes parallel to the main surface 11b of the pallet 11 (step S112). Furthermore, based on the detected value from the lift sensor 22, the controller 30 controls the lift cylinder 23 to raise and lower the forks 12 to a height position where the tine section 18 of the forks 12 does not touch the inner wall surface of the pallet 11 (step S113). Note that steps S112 and S113 can be executed simultaneously.

[0061] After performing step S110 or step S113 described above, the control unit 30 controls the gripping cylinder 25 to remove the forks 12 from the pallet 11 (step S114).

[0062] Fig. Figure 5 is a flowchart illustrating details of step S114. Fig. 5. Based on the detected value from the tilt angle sensor 21 (step S121), the controller 30 determines whether the loading platform 16 of the truck 15 is tilted at a prescribed angle or greater. The prescribed angle of inclination is an angle at which the tine section 18 of the forks 12 does not come into contact with the pallet 11 when the forks 12 are removed from the pallet 11 as it is.

[0063] If it is determined that the loading platform 16 is not inclined by the prescribed angle of inclination or more (see Fig. 6A to 6C), the control 30 controls the gripping cylinder 25 so that the forks 12 are removed from the pallet 11 (step S122).

[0064] If it is determined that the loading platform is inclined by the prescribed angle of inclination or more (see Fig. 7A to 9C), the controller 30 determines, based on the detected value of the tilt angle sensor 21 (step S123), whether the tilt of the loading platform 16 is lowered towards the front (the side of the forklift 2) or not.

[0065] If it is determined that the inclination of the load 16 is lowered towards the front (see Fig. 7A to 7C and Fig. 8), the control 30 controls the gripping cylinder 25 so that the forks 12 are removed from the pallet 11, and controls the lifting cylinder 23 to lower the forks 12 in the front-back direction according to the amount of movement of the forks 12 detected by the motion sensor 29 (step S124).

[0066] At this point, the controller 30 adjusts the lowering amount of the forks 12 according to the amount of movement of the forks 12 in the front-back direction, so that the forks 12 do not come into contact with the pallet 11 when the forks 12 are removed from the pallet 11. In particular, the controller 30 generates a target track L on the extension of the tine section 18 of the forks 12 based on the tilt angle θ of the forks 12 detected by the tilt angle sensor 21 and adjusts the lowering amount of the forks 12 so that the tine section 18 moves along the target track L (see Fig. 8).

[0067] If it is determined that the inclination of the load 16 is not in the front-back direction, but in the back-back direction (see Fig. 9A to 9C), the control 30 controls the gripping cylinder 25 to remove the forks 12 from the pallet 11, and controls the lifting cylinder 23 to raise the forks 12 in the front-back direction according to the amount of movement of the forks 12 detected by the motion sensor 29 (step S125).

[0068] At this point, the controller 30 adjusts the stroke of the forks 12 according to their forward-backward movement, ensuring that the forks 12 do not come into contact with the pallet 11 when they are moved away from it. Specifically, the controller 30 generates a target track L on the extent of the tine section 18 of the forks 12 based on the tilt angle θ of the forks 12 detected by the tilt angle sensor 21, and adjusts the stroke of the forks 12 so that the tine section 18 moves along the target track L.

[0069] Here, the point cloud extraction unit 31 executes steps S101, S102, S105, and S106. The unit for storing data from the reference point cloud 32 executes step S103. The lowering control unit 33 executes steps S104, S110, and S111. The change amount estimation unit 34 for position / posture executes step S107. The determination unit 35 for creating the palette executes steps S108 and S109. The tilt control unit 36 ​​executes step S112. The control unit 37 for lifting executes step S113. The retraction control unit 38 executes step S114.

[0070] As described above and in Fig. As illustrated in Figure 6A, when unloading cargo onto the loading platform 16, which is not inclined in the direction of the forklift 2's tilt, the forks 12 holding the pallet 11 are first lowered towards the loading platform 16 by the lifting cylinder 23. The pallet 11 then rests on the upper surface 16a of the cargo 16. Since the main surface 11b of the pallet 11 is parallel to the upper surface 16a of the cargo 16 at this point, the tilt angle of the pallet 11 relative to the forks 12 does not change, even though the pallet 11 is resting on the upper surface 16a of the cargo 16.

[0071] But even after the pallet 11 rests on the upper surface 16a of the load 16, the lowering of the forks 12 continues. Therefore, as in Fig. Figure 6B illustrates a gap between the forks 12 and the upper inner wall surface of the pallet 11, and the height position of the pallet 11 relative to the forks 12 changes to be higher. When the amount of change in the position of the pallet 11 relative to the forks 12 reaches the threshold value, the lowering of the forks 12 by the lifting cylinder 23 is stopped (see steps S108 to S110 in Fig. ). At this point, the forks 12 have no contact with the upper and lower inner wall surfaces of the pallet 11.

[0072] Then the forks 12 are removed from the pallet 11, as shown in Fig. 6C illustrates (see steps S121 and S122 in Fig. 5) when the gripping cylinder 25 retracts the forks 12 or the forklift 2 is retracted. This completes the unloading of the cargo from the loading platform 16.

[0073] As in Fig. Figure 7A illustrates that during unloading on the loading platform 16, which is inclined downwards towards the forklift 2, the forks 12 holding the pallet 11 are lowered as described above. The pallet 11 then rests on the upper surface 16a of the load 16.

[0074] Since the upper surface 16a of the cargo 16 is inclined towards the front, as in Fig. As illustrated in Figure 7B, at this point the rear end of the underside of the pallet 11, held by the forks 12, initially rests against the upper surface 16a of the load 16. As the pallet 11 tilts along the upper surface 16a of the load 16, the tilt angle of the pallet 11 relative to the forks 12 changes. If the change in the tilt angle of the pallet 11 relative to the forks 12 exceeds the threshold value, the lowering of the forks 12 by the lifting cylinder 23 is stopped (see steps S108 to S111 in Figure 7B). Fig. ).

[0075] Then, as in Fig. As illustrated in Figure 7C, the tilting cylinder 24 tilts the forks 12 backwards so that the tine section 18 of the forks 12 is parallel to the main surface 11b of the pallet 11, and the lifting cylinder 23 lowers the forks 12 slightly so that the tine section 18 of the forks 12 does not touch the inner wall surface of the pallet 11 (see steps S112 and S113 in Fig. 4) As a result, gaps form between the forks 12 and the upper and lower inner wall surfaces of the pallet 11.

[0076] Then the forks 12 are removed from the pallet 11, as shown in Fig. Figure 8 illustrates when the gripping cylinder 25 causes the forks 12 to retract or the forklift 2 is retracted. At this point, the forks 12 are removed from the pallet 11 while being lowered so that they do not come into contact with the inner wall surface of the pallet 11 (see steps S123 and S124 in Figure 8). Fig. Therefore, when the forks 12 are removed from the pallet 11, it is prevented that the forks 12 get stuck on the inner wall surface of the pallet 11.

[0077] As in Fig. As illustrated in Figure 9A, when unloading onto the loading platform 16, which is inclined downwards towards the opposite side of the forklift 2 (rear), the forks 12 holding the pallet 11 are lowered as described above. The pallet 11 then rests on the upper surface 16a of the load 16.

[0078] Since the upper surface 16a of the cargo 16 is inclined towards the rear, as in Fig. As illustrated in Figure 9B, at this point the front end of the lower surface of the pallet 11, held by the forks 12, is initially in contact with the upper surface 16a of the load 16. As the pallet 11 tilts along the upper surface 16a of the load 16, the tilt angle of the pallet 11 relative to the forks 12 changes. If the change in the tilt angle of the pallet 11 relative to the forks 12 exceeds the threshold value, the lowering of the forks 12 by the lifting cylinder 23 is stopped (see steps S108 to S111 in Figure 9B). Fig. ).

[0079] Then, as in Fig. As illustrated in Figure 9C, the tilting cylinder 24 tilts the forks 12 forward so that the tine section 18 of the forks 12 is parallel to the main surface 11b of the pallet 11, and the lifting cylinder 23 slightly raises the forks 12 so that the tine section 18 of the forks 12 does not touch the inner wall surface of the pallet 11 (see steps S112 and S113 in Fig. 4) This creates gaps between the forks 12 and the upper and lower inner wall surfaces of the pallet 11.

[0080] The forks 12 are then removed from the pallet 11 when the gripping cylinder 25 retracts the forks 12 or the forklift 2 is retracted. At this point, the forks 12 are removed from the pallet 11 while being raised so that they do not come into contact with the inner wall surface of the pallet 11 (see steps S123 and S125 in Fig. 5) Therefore, when the forks 12 are removed from the pallet 11, it is prevented that the forks 12 remain stuck on the inner wall surface of the pallet 11.

[0081] As described above, in the present embodiment, when the load is unloaded from the loading platform 16 of the truck 15, the lifting cylinder 23 is controlled to lower the forks 12, which hold the pallet 11, towards the loading platform 16. At this point, the pallet 11 held by the forks 12 is detected, the angle of inclination of the forks 12 is determined, and the change in the position of the pallet 11 relative to the forks 12 is estimated. Subsequently, based on the change in the position of the pallet 11 relative to the forks 12, it is determined whether the pallet 11 held by the forks 12 is resting on the upper surface 16a of the load 16 or not. If the pallet 11 is resting on the upper surface 16a of the load 16, the position of the pallet 11 relative to the forks 12 changes.The change in the position of pallet 11 relative to the forks 12 indicates whether pallet 11 is resting on the upper surface 16a of the load 16, which is tilted in the direction of the inclination. If it is determined that pallet 11, held by the forks 12, is resting on the upper surface 16a of the load 16, the tilting cylinder 24 is controlled so that the forks 12 tilt in a direction approaching the main surface 11b of pallet 11. The forklift 2 is then controlled to lift the forks 12 from pallet 11 according to their tilt angle. If pallet 11 is resting on the upper surface 16a of the load 16, which is tilted in the direction of the inclination, pallet 11 is tilted according to the inclination of the load 16. However, since the forks 12 are inclined in a direction that approaches the main surface 11b of the pallet 11, it is prevented that the forks 12 touch the inner wall surface of the pallet 11.This allows the forks 12 to be gently removed from the pallet 11 when a load is to be unloaded from the loading platform 16, which is inclined in the direction of the incline. Consequently, it is possible to handle such a case even if the degree of inclination of the loading platform 16 changes in the direction of the incline due to the load on the loading platform 16 of the truck 15 caused by the action of the truck's suspension.

[0082] By detecting the pallet 11 held by the forks 12 and estimating the amount of change in the position of the pallet 11 relative to the forks 12, the unloading of cargo on the inclined loading surface 16 can be carried out without being restricted by the shape or similar of the cargo M located on the pallet 11.

[0083] Furthermore, in the present embodiment, the point cloud data of the pallet 11 are referenced three-dimensionally, and when the forks 12 holding the pallet 11 are lowered in a state in which the inclination angle of the forks 12 is constant, and the latest point cloud data of the pallet 11 are periodically compared with the reference point cloud data of the pallet 11, the amount of change in the position of the pallet 11 with respect to the forks 12 can be easily estimated.

[0084] Furthermore, in the present embodiment, the amount of change in the height position and the orientation of the pallet 11 relative to the forks 12 determines whether the pallet 11, held by the forks 12, rests on the upper surface 16a of the load 16 or not. If the pallet 11 rests on the upper surface 16a of the load 16, its height and orientation relative to the forks 12 change. If the pallet 11 rests on the non-inclined upper surface 16a of the load 16, its height relative to the forks 12 changes, but its orientation relative to the forks 12 does not change. When the pallet 11 rests on the upper surface 16a of the load 16 which is inclined in the direction of the inclination, the forks 12 are therefore inclined in a direction which approaches the main surface 11b of the pallet 11, since the pallet 11 is inclined according to the inclination of the load 16.If, on the other hand, the pallet 11 rests on the upper surface 16a of the load 16, which is not inclined, the forks 12 are not necessarily inclined.

[0085] Furthermore, in the present embodiment, if the change in the position of the pallet 11 relative to the forks 12 is greater than the threshold for the angle, the pallet 11 rests on the upper surface 16a of the load 16, which is inclined in the direction of the inclination, and the forks 12 tilt in a direction approximately parallel to the main surface 11b of the pallet 11. If the change in the position of the pallet 11 relative to the forks 12 is equal to or less than the threshold for the angle and the change in the position of the pallet 11 relative to the forks 12 is equal to or greater than the threshold for the height, the pallet 11 rests on the non-inclined upper surface 16a of the load 16 and the forks 12 do not tilt.

[0086] Fig. Figure 10 is a block diagram illustrating a configuration of a discharge control device according to a second embodiment of the present invention. Fig. 10, an unloading control device 1A of the present embodiment comprises a pallet holding sensor 27 instead of the lifting sensor 22 of the first embodiment.

[0087] The pallet holding sensor 27 is a sensor (pallet holding detector) that detects whether the pallet 11 is being held by the forks 12. For example, a contact sensor or similar device attached to the forks 12 is used as the pallet holding sensor 27. The pallet holding sensor 27 outputs an ON signal when it detects that the pallet 11 is being held by the forks 12.

[0088] Furthermore, the unloading control device 1A comprises a control unit 30A instead of the control unit 30 in the preceding first embodiment. The control unit 30A comprises a point cloud extraction unit 31, a reference point cloud data storage unit 32, a lowering control unit 33, a change amount estimation unit 39, a position determination unit 35A, a tilt determination unit 36, a lifting control unit 37A, and a retraction control unit 38.

[0089] When the forks 12 holding the pallet 11 are lowered, the change amount estimation unit 39 represents a change amount estimation unit that estimates the extent of the change in the attitude of the pallet 11 with respect to the forks 12 based on the data extracted by the point cloud extraction unit 31 and the tilt angle of the forks 12 detected by the tilt angle sensor 21.

[0090] The pallet detection unit 35A determines whether the pallet 11 held by the forks 12 rests on an upper surface 16a of the load 16 or not, based on the extent of the change in the position of the pallet 11 relative to the forks 12 estimated by the change amount estimation unit 39 and an output signal (detection result) from the pallet holding sensor 27.

[0091] If the change in the position of pallet 11 relative to the forks 12 is greater than the angle threshold, the detection unit 35A determines that the pallet 11 held by the forks 12 is resting on the upper surface 16a of the load 16. If the change in the position of pallet 11 relative to the forks 12 is equal to or less than the threshold, and the pallet holding sensor 27 determines that the pallet 11 is not held by the forks 12, the pallet detection unit 35A determines that the pallet 11 held by the forks 12 is resting on the upper surface 16a of the loading platform 16.

[0092] The pallet stop determination unit 35A represents a determination unit that determines whether the pallet 11 held by the forks 12 rests on the upper surface 16a of the load 16 of the truck 15 or not, based on the amount of change in the holding of the pallet 11 in relation to the forks 12 estimated by the change amount estimation unit 39.

[0093] When the pallet detection unit 35A determines that the pallet 11 held by the forks 12 is resting on the upper surface 16a of the load 16, the tilt control unit 36 ​​controls the tilt cylinder 24 so that the forks 12 tilt in a direction parallel to a main surface 11b of the pallet 11, based on the detected value of the tilt angle sensor 21.

[0094] If the determination unit 35A determines that the pallet 11 held by the forks 12 rests on the upper surface 16a of the load 16, the control unit 37A controls the lifting cylinder 23 so that it raises and lowers the forks 12 in a direction that does not touch the inner wall surface of the pallet 11, based on the output signal of the pallet holding sensor 27.

[0095] Fig. Figure 11 is a flowchart that indicates the process of controlling the discharge, which is to be carried out by the controller 30A, and corresponds to Fig. 4. In Fig. 11. The controller 30A executes the steps S101 to S106 described above.

[0096] After executing step S106, the controller 30A estimates the change in the tilt angle of the pallet 11 relative to the forks 12 based on the latest point cloud data determined in step S106, the reference point cloud data stored in step S103, and the values ​​acquired by the tilt angle sensor 21 (step S117). The controller 30A extracts the difference between the latest point cloud data and the reference point cloud data to estimate the change in the tilt angle of the pallet 11 relative to the forks 12.

[0097] The controller 30A then executes step S108 described above. If the controller 30A determines that the change in the tilt angle of the pallet 11 with respect to the forks 12 is equal to or less than the threshold value, it determines whether the output signal of the pallet holding sensor 27 is an OFF signal or not (step S109A).

[0098] If it is determined that the output signal of the pallet holding sensor 27 is not the OFF signal but the ON signal, the controller 30A executes the preceding step S104 again. If it is determined that the output signal of the pallet holding sensor 27 is the OFF signal, the controller 30A executes the preceding step S110.

[0099] If it is determined that the change in the tilt angle of the pallet 11 with respect to the forks 12 is not equal to or less than the angle threshold value in step S108, the controller 30A executes steps S111 and S112 as described above.

[0100] Furthermore, the controller 30A controls the lifting cylinder 23 to raise and lower the forks 12 based on the output signal of the pallet holding sensor 27 to a position where the tine section 18 of the forks 12 does not touch the inner wall surface of the pallet 11 (step S113A). That is, the controller 30A controls the lifting cylinder 23 to raise and lower the forks 12 until the output signal of the pallet holding sensor 27 becomes the OFF signal. Note that steps S112 and S113A can be executed simultaneously.

[0101] The controller 30A executes step S114 after executing step S110 or step S113A.

[0102] Here, the point cloud extraction unit 31 executes steps S101, S102, S105, and S106. The unit for storing data from the reference point cloud 32 executes step S103. The lowering control unit 33 executes steps S104, S110, and S111. The estimation unit 39 for estimating the change in position executes step S117. The determination unit 35A for creating the pallet executes steps S108 and S109A. The tilt control unit 36 ​​executes step S112. The control unit 37A for lifting executes step S113A. The retraction control unit 38 executes step S114.

[0103] As described above, in the present embodiment, the amount of change in the position of the pallet 11 relative to the forks 12 and the detection result determine whether the pallet 11, held by the forks 12, rests against the upper surface 16a of the load 16 or not. If the pallet 11 rests against the upper surface 16a of the load 16, which is inclined in the direction of the inclination, the position of the pallet 11 relative to the forks 12 changes to a state in which the pallet 11 is held by the forks 12. If the pallet 11 rests against the upper surface 16a of the load 16, which is not inclined, the pallet 11 is not held by the forks 12, but the position of the pallet 11 relative to the forks 12 does not change.When the pallet 11 rests on the upper surface 16a of the inclined load 16, the forks 12 are inclined in a direction approximately parallel to the main surface 11b of the pallet 11, since the pallet 11 is inclined according to the inclination of the load 16. When the pallet 11 rests on the upper surface 16a of the load 16, which is not inclined, the forks 12 are not necessarily inclined.

[0104] Furthermore, in the present embodiment, if the change in the position of the pallet 11 relative to the forks 12 is greater than the angle threshold, the pallet 11 rests on the upper surface 16a of the load 16, which is inclined in the direction of the inclination, and the forks 12 tilt in a direction approaching the main surface 11b of the pallet 11. If the change in the position of the pallet 11 relative to the forks 12 is equal to or less than the angle threshold and the pallet 11 is not held by the forks 12, the pallet 11 rests on the upper surface 16a of the load 16, which is not inclined, and the forks 12 do not tilt.

[0105] Furthermore, in the present embodiment, by using the pallet holding sensor 27, which detects whether the pallet 11 is held by the forks 12 or not, it is possible to precisely detect whether the forks 12 are in a state in which they are in contact with the pallet 11 or not, even if an estimation error occurs in the height position of the pallet 11 with respect to the forks 12 depending on the mounting position of the RGBD camera 20.

[0106] It should be noted that the present invention is not limited to the present embodiment. For example, in the preceding embodiment, lifting control units 37 and 37A are provided, which control the lifting cylinders 23 such that the forks 12 are raised and lowered in a direction in which the forks 12 do not come into contact with the inner wall surface of the pallet 11 when the pallet 11 held by the forks 12 rests against the upper surface 16a of the load 16. However, if it is determined that the pallet 11 held by the forks 12 rests against the upper surface 16a of the load 16 and the forks 12 do not come into contact with the inner wall surface of the pallet 11, the lifting control units 37 and 37A can be omitted.

[0107] Furthermore, in the present embodiment, the reference point cloud data are determined based on the initial point cloud data first acquired by the RGBD camera 20 at the beginning of the lowering of the forks 12 holding the pallet 11, but the present invention is not specifically limited to such a form. For example, the point cloud data acquired by the RGBD camera 20 can be corrected as new reference point cloud data during the lowering of the forks 12 holding the pallet 11.

[0108] Furthermore, in the embodiment described above, the pallet 11 held by the forks 12 is imaged by the RGBD camera 20, and the three-dimensional point cloud of the pallet 11 is obtained. However, the present invention is not specifically limited to the RGBD camera 20, and the three-dimensional point cloud of the pallet 11 can be obtained, for example, with a time-of-flight (ToF) camera, a LiDAR (Light Detection and Ranging) system, or similar technology. Moreover, a plurality of RGBD cameras 20 or the like can be provided instead of a single one, and the three-dimensional point cloud of the pallet 11 can be obtained using the point cloud data combined from the plurality of RGBD cameras 20 or the like.

[0109] Furthermore, in the present embodiment, as described above, the change in the position of the pallet 11 relative to the forks 12 is estimated by comparing the latest point cloud data with the reference point cloud data when the forks 12 holding the pallet 11 are lowered. However, the present invention is not specifically limited to such a form. For example, the change in the position of the pallet 11 relative to the forks 12 can be estimated by obtaining image data of the pallet 11 held by the forks 12 and comparing the latest image data with the reference image data.

[0110] Furthermore, in the preceding embodiment, unloading is carried out on the loading platform 16, which is inclined in the direction of the incline by the suspension of the truck 15. However, the present invention is not specifically limited to the loading platform 16 of the truck 15, and unloading can also take place on a loading section inclined in the direction of the incline.

[0111] In the present embodiment, unloading is carried out using a reach truck, but the present invention is not particularly limited to this, and unloading can also be carried out using a forklift. In this case, the forklift is withdrawn to remove the forks 12 from the pallet 11. Reference symbol list 1, 1A Discharge Control Device 2 FORKLIFTS 11 PALLETS 11b MAIN AREA 12 FORKS 16 CHARGING AREA (CHARGING SECTION) 16a UPPER SURFACE 20 RGBD camera (pallet detection unit) 21 Tilt Angle Sensor (Tilt Angle Detector) 22 LIFT SENSOR (HEIGHT POSITION DETECTOR) 23 HOVE CYLINDERS 24 INCLINATION CYLINDERS 27 Pallet Holding Sensor (Pallet Holding Detector) 31 POINT CLOUD EXTRACTION UNIT (PALLET CAPTURE UNIT) 33 Lowering Control Unit 34 POSITION / ATTITUDE CHANGE AMOUNT ESTIMATE UNIT (CHANGE AMOUNT ESTIMATE UNIT) 35, 35A Pallet Support Unit (Definition Unit) 36 INCLINATION CONTROL UNIT 38 RETRACT CONTROL UNIT 39 ESTIMATED CHANGE OF ATTITUDE UNIT (ESTIMATED CHANGE OF ATTITUDE UNIT)

Claims

Unloading control device (1, 1A) for loading a pallet (11) held by the forks (12) of a forklift (2) onto a loading section in order to remove the forks (12) from the pallet (11), the unloading control device (1, 1A) comprising: a pallet detection unit (31) configured to detect the pallet (11) held by the forks (12) and to obtain detection data of the pallet (11); a tilt angle detector (21) configured to detect a tilt angle of the forks (12); a lowering control unit (33) configured to control a lifting cylinder (23) of the forklift (2) such that the forks (12) holding the pallet (11) are lowered towards the loading section;a change amount estimation unit (39) configured to estimate the amount of change in the position of the pallet (11) relative to the forks (12) based on the pallet (11) detection data obtained from the pallet detection unit (31) and the tilt angle of the forks (12) detected by the tilt angle detector (21) when the forks (12) holding the pallet (11) are lowered; a determination unit (35) configured to determine whether the pallet (11) held by the forks (12) is resting on an upper surface of the loading section or not, based on the amount of change in the position of the pallet (11) relative to the forks (12) estimated by the change amount estimation unit (39);a tilt control unit (36) configured to control a tilt cylinder of the forklift (2) such that the forks (12) tilt in a direction that approaches a main surface of the pallet (11) parallel to the main surface of the pallet (11) when the determination unit (35) determines that the pallet (11) held by the forks (12) is resting on an upper surface of the loading section;and a retraction control unit (38) configured to control the forklift (2) to remove the forks (12) from the pallet (11) according to the tilt angle of the forks (12) detected by the tilt angle detector (21) after the forks (12) approach parallel to the main surface of the pallet (11), wherein the pallet sensing unit (31) acquires point cloud data of the pallet (11) in three dimensions, and when the forks (12) holding the pallet (11) are lowered, the change amount estimation unit (39) compares the most recent point cloud data of the pallet (11) obtained by the pallet sensing unit (31) with reference point cloud data of the pallet (11) obtained prior to the most recent point cloud data from the pallet sensing unit (31) to estimate a change amount of a position of the pallet (11) with respect to the forks (12). Unloading control device (1, 1A) according to claim 1, further comprising a height position detector (22) configured to detect a height position of the forks (12), wherein the change amount estimation unit (39) estimates a change amount of a height position and attitude of the pallet (11) with respect to the forks (12) based on detection data of the pallet (11) obtained from the pallet detection unit (31), a height position of the forks (12) detected by the height position detector (22), and an inclination angle of the forks detected by the inclination angle detector (21) when the forks (12) holding the pallet (11) are lowered, and the determination unit (35) determines whether the pallet (11) held by the forks (12) is resting on an upper surface of the loading section.based on the amount of change in the height position and attitude of the pallet (11) in relation to the forks (12) estimated by the change amount estimation unit (39). Unloading control device (1, 1A) according to claim 2, wherein the determining unit (35) determines that the pallet (11) held by the forks (12) rests on the upper surface of the loading section when the change in the position of the pallet (11) relative to the forks (12) is greater than a first threshold, and determines that the pallet (11) held by the forks (12) rests on the upper surface of the loading section when the change in the position of the pallet (11) relative to the forks (12) is equal to or less than the first threshold and a change in the height position of the pallet (11) relative to the forks (12) is equal to or greater than a second threshold, and the tilting control unit (36) controls the tilting cylinder such that the forks (12) tilt in a direction that approximates a principal surface of the pallet (11).if the amount of change in the position of the pallet (11) in relation to the forks (12) is greater than the first threshold. Unloading control device (1, 1A) according to claim 1, further comprising a pallet holding detector (27) configured to detect whether the pallet (11) is held by the forks (12) or not, wherein the determination unit (35) determines whether the pallet (11) held by the forks (12) rests on an upper surface of the loading section or not, based on the amount of change in the position of the pallet (11) relative to the forks (12) estimated by the change amount estimation unit (39) and a detection result of the pallet holding detector (27). Unloading control device (1, 1A) according to claim 4, wherein the determination unit (35) determines that the pallet (11) held by the forks (12) rests on the upper surface of the loading section when the change in the position of the pallet (11) relative to the forks (12) is greater than a threshold value, and determines that the pallet (11) held by the forks (12) rests on the upper surface of the loading section when the change in the position of the pallet (11) relative to the forks (12) is equal to or less than the threshold value and the pallet position detector (27) detects that the pallet (11) is not held by the forks (12), and the tilt control unit (36) controls the tilt cylinder such that the forks (12) tilt in a direction that approximates parallel to a principal surface of the pallet (11) when the change in the position of the pallet (11) is With reference to the forks (12) greater than the threshold.

Images