Workpiece conveying device

Abstract

To provide a workpiece conveying device which can detect a position of a workpiece with a simple configuration.SOLUTION: A depalletizing apparatus 10 includes: a chuck 20 which grips a workpiece W; a conveyance mechanism 30 which moves the chuck 20; a control device 100 which controls the chuck 20 and the conveyance mechanism 30; and a laser sensor which measures a distance. The control device 100 causes the chuck 20 to grip the workpiece W after moving the chuck 20 by the conveyance mechanism 30 on the basis of a moving direction and a moving distance of the chuck 20 stored by defining a reference point as a reference when depalletization is executed. Before the execution of the depalletization, a distance in a vertical direction up to an object is measured while horizontally moving the laser sensor on an upper side of the workpiece W mounted on a pallet P, a workpiece end is detected on the basis of the measurement result, and a position in a horizontal direction of the reference point is corrected on the basis of the detected workpiece end.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a workpiece transport device that transports a workpiece. [Background technology]

[0002] Conventionally, there is known a work transport device that performs depalletizing, which unloads workpieces from a pallet for transporting the workpieces (for example, Patent Document 1). The work transport device described in Patent Document 1 first captures an image of the workpieces loaded on the pallet with a camera, and calculates center of gravity coordinate data of the workpieces by performing image processing such as pattern matching on the captured image of the workpieces. The work transport device then depalletizes the items based on the calculated center of gravity coordinate data of the workpieces. In this way, the work transport device described in Patent Document 1 can automatically perform depalletizing even if it is unknown where the workpieces are placed on the pallet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-13913 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when performing image processing, the load of image processing is heavy, and the program for image processing is likely to become complicated. This tendency is particularly strong when using deep learning AI. In addition, a certain level of resolution is required for the camera. Therefore, when detecting the position of a workpiece using a camera as shown in Patent Document 1, there is a problem that the required performance of the microcomputer and camera used in the workpiece transport device tends to be high, and the cost tends to be high.

[0005] The present invention has been made in consideration of the above circumstances, and has as its main object to provide a workpiece transport device capable of detecting the position of a workpiece with a simple configuration. [Means for solving the problem]

[0006] The work transport device that solves the above problem is a work transport device that depalletizes a group of workpieces in which a plurality of workpieces are placed on a pallet as a unit, and when palletizing, each of the workpieces that make up the group of workpieces is arranged in one or more rows in two orthogonal directions, and a relative position of each workpiece is determined in advance with respect to a reference point set on the pallet, and the work transport device includes a chuck unit that grips the workpiece, a moving unit that moves the chuck unit, a memory unit that stores relative position information of each workpiece at the time of palletizing with respect to the reference point, and when performing the depalletizing, the position information of each workpiece stored in the memory unit. The system is equipped with a calculation processing device that controls the chuck unit and the moving unit so that the chuck unit grips the workpiece after the chuck unit is moved by the moving unit based on the position information, and a distance measuring sensor that measures distance, and before performing the depalletizing, the calculation processing device measures the vertical distance to the target object while moving the distance measuring sensor horizontally above the group of works placed on the pallet, detects the positions of two orthogonal outer surfaces of at least the outer surfaces of the group of works based on the measurement results, and corrects the horizontal position of the reference point based on the positions of the two detected outer surfaces.

[0007] In the above configuration, before depalletizing, the distance to the target is measured while moving the distance measuring sensor horizontally above the work group placed on the pallet, the positions of two orthogonal outer surfaces of the work group are detected based on the measurement results, and the position of the reference point is corrected based on the positions of the two detected outer surfaces. This makes it possible to correct the reference point with simple processing even if the position of the work group placed on the pallet is shifted.

[0008] Therefore, when depalletizing, even if the chuck section is moved by the moving section based on the relative position information of each workpiece with respect to the reference point stored in the memory section, the horizontal deviation of the reference point is corrected, so the chuck section can be moved to an appropriate position. [Brief description of the drawings]

[0009] [Figure 1] FIG. [Diagram 2] (a) is a perspective view of the chuck, and (b) is a side view of the chuck. [Diagram 3] FIG. [Figure 4] Schematic diagram of a laser sensor. [Diagram 5] 13 is a flowchart of a correction process. [Figure 6] FIG. 4 is a plan view showing a movement trajectory of a laser sensor. [Figure 7] FIG. 11 is a diagram showing the measurement results of a laser sensor. [Figure 8] FIG. 4 is a schematic diagram of a laser sensor of a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the "workpiece transport device" according to the present invention will be described with reference to the drawings. In the following embodiments and modified examples, the same or equivalent parts are denoted by the same reference numerals in the drawings, and the explanation of the same reference numerals is incorporated herein. In addition to the combination of configurations explicitly shown in the description of the embodiments and modified examples, it is also possible to combine the embodiments and modified examples as long as there is no particular problem with the combination.

[0011] As shown in Fig. 1, the depalletizing device 10 as a work transport device is a device that sequentially transports the workpieces W aligned and loaded on a portable pallet P installed at a predetermined position to a predetermined discharge location, i.e., a depalletizing device. The workpieces W are rectangular boxes, such as cardboard boxes, and are discharged onto external transport equipment (such as a belt conveyor) via a roller conveyor 1 or the like. This will be described in detail below.

[0012] 1, the depalletizing apparatus 10 includes a chuck device 20 (hereinafter simply referred to as the chuck 20) ​​as a chuck unit that grips the workpiece W, a transport mechanism 30 as a moving unit that moves the chuck 20, and a rectangular parallelepiped frame 70 to which the transport mechanism 30 is fixed. The depalletizing apparatus 10 also includes a control device 100 as a calculation processing device that controls the operations of the chuck 20 and the transport mechanism 30, and a controller (not shown) as an information terminal that can input and output various information.

[0013] In this embodiment, the longitudinal direction of the frame 70 is defined as the X-axis direction, the lateral direction (direction perpendicular to the X-axis) is defined as the Y-axis direction, and the direction perpendicular to the X-axis and Y-axis directions is defined as the Z-axis direction. Since the depalletizing apparatus 10 is usually installed on a flat surface, the Z-axis direction corresponds to the up-down direction. The X-axis and Y-axis directions correspond to the horizontal direction.

[0014] The conveying mechanism 30 has a pillar portion 50 fixed to a frame body 70 and formed to extend along the Z-axis direction, and an arm portion 60 fixed to the pillar portion 50 and formed to extend along the Y-axis direction.

[0015] An X-axis guide rail 51 is provided on the frame 70 along the X-axis direction, and the pillar portion 50 is fixed to the X-axis guide rail 51 so as to be movable along the X-axis direction. The pillar portion 50 is drivingly connected via a toothed belt or the like to the output shaft of an X-axis servo motor (not shown) disposed at the bottom of the frame 70. In other words, the pillar portion 50 is configured to reciprocate in the X-axis direction along the X-axis guide rail 51 based on the driving force of the X-axis servo motor.

[0016] A Z-axis guide rail 61 is provided on the pillar portion 50 along the Z-axis direction, and the arm portion 60 is fixed to the Z-axis guide rail 61 so as to be movable along the Z-axis direction. The arm portion 60 is drivingly connected to the output shaft of a Z-axis servo motor provided on the pillar portion 50 via a toothed belt or the like. In other words, the arm portion 60 is configured to reciprocate in the Z-axis direction along the Z-axis guide rail 61 based on the driving force of the Z-axis servo motor.

[0017] A Y-axis guide rail 21 is provided on the arm unit 60 along the Y-axis direction, and the chuck 20 is fixed to be movable along the Y-axis direction relative to the Y-axis guide rail 21. The chuck 20 is drivingly connected to the output shaft of a Y-axis servo motor provided on the arm unit 60 via a toothed belt or the like. In other words, the chuck 20 is configured to reciprocate in the Y-axis direction along the Y-axis guide rail 21 based on the driving force of the Y-axis servo motor.

[0018] As described above, the transport mechanism 30 is configured to be able to linearly move the chuck 20 in two directions (X-axis direction and Y-axis direction) perpendicular to the horizontal direction, and in the vertical direction (Z-axis direction).

[0019] 1, the chuck 20 is fixed to the arm unit 60 via a rotation mechanism 23 serving as a rotation unit. The rotation mechanism 23 is configured to be able to rotate the chuck 20 around the Z axis (in the direction of arrow R in FIG. 1) with the rotation mechanism 23 as the center based on the driving force of a built-in rotation servo motor (not shown).

[0020] As shown in FIG. 2, the chuck 20 has a rectangular base 24 attached to the rotation mechanism 23. The base 24 has a facing surface 25 at its lower part that faces the upper surface of the workpiece W. The base 24 is fixed to the rotation mechanism 23 so that the facing surface 25 is perpendicular to the Z axis. A first suction pad 26 that adsorbs the workpiece W is provided on this facing surface 25. In this embodiment, a plurality of first suction pads 26 are provided. An ejector is connected to each first suction pad 26 via an air pipe (not shown). The inside of the first suction pad 26 becomes negative pressure due to the operation of the ejector, which makes it possible to adsorb the upper surface of the workpiece W.

[0021] In addition, a support piece 41 is provided on the outer edge side of the opposing surface 25 of the base 24. In this embodiment, the support piece 41 is attached to an end portion in the short side direction of the base 24. The support piece 41 is disposed only on one side in the short side direction with the base 24 (opposing surface 25) as the center.

[0022] The support piece 41 is formed in a substantially rectangular plate shape so as to support the side of the workpiece W, and is attached so that its tip faces downward, that is, so as to hang down, from the base 24. In this case, the support piece 41 is attached so that the surface of the support piece 41 faces the opposing surface 25 side (i.e., the side of the side of the workpiece W). In other words, the support piece 41 is arranged so that when the tip of the support piece 41 is positioned downward along the Z-axis direction (perpendicular to the opposing surface 25), the perpendicular direction of the side of the support piece 41 faces the short side direction. In this case, the side of the support piece 41 facing the opposing surface 25 side is referred to as the inner side surface 41a, and the opposite side surface is referred to as the outer side surface 41b.

[0023] On the inner side surface 41a of the support piece 41, a second suction pad 44 is provided as a side surface suction pad that suctions the side surface of the workpiece W. In this embodiment, a plurality of second suction pads 44 are provided. Like the first suction pad 26, each second suction pad 44 is connected to an ejector via an air pipe (not shown), and the inside of the second suction pad 44 is made negative pressure by the ejector, thereby making it possible to suction the side surface of the workpiece W.

[0024] The control device 100 is an electronic control device equipped with a well-known microcomputer consisting of a CPU, ROM, RAM, flash memory, etc. The control device 100 is equipped with a drive circuit for driving the various servo motors described above, and is configured to be able to control the operation of the various servo motors via the drive circuit. The control device 100 is also configured to be able to operate the ejector to control the suction operation of the workpiece W by the first suction pad 26 and the second suction pad 44.

[0025] The control device 100 is connected to various sensors, various servo motors, a controller, etc., and is configured to be able to acquire various information. The control device 100 also has various functions, and executes the various functions based on the acquired information. These functions are realized by executing a program stored in a storage device (storage memory) included in the control device 100. The various functions may be realized by electronic circuits, which are hardware, or at least a part of them may be realized by software, i.e., processing executed on a computer.

[0026] Among the various functions, for example, there is a depalletizing function that transports the workpieces W loaded on the pallet P one by one. The depalletizing function is briefly described as a function that grips each workpiece W loaded on the pallet P with a chuck 20 and transports it from the pallet P to a predetermined discharge location. With this function, the workpieces W are transferred to a predetermined position without manual intervention from a state in which the workpieces W are stacked in multiple tiers in the vertical direction (Z-axis direction) on the pallet P, for example, as shown in FIG. 3. In FIG. 3, the workpieces W are stacked in multiple tiers on the pallet P with pinholes. In addition, in this embodiment, a collection of workpieces W (a group of workpieces) stacked on the pallet P as shown in FIG. 3 may be referred to as a load Crg.

[0027] However, when depalletizing, if the position of the workpiece W loaded on the pallet P is detected by processing the image captured by a camera or the like, the processing load is large, and therefore a high-performance processing device is required. In addition, since a certain degree of resolution is also required for the captured image, it is desirable for the camera to have high performance. If the performance is increased in this way, the price of the device will also increase, making it difficult to spread. Therefore, in this embodiment, a depalletizing device 10 with a simple configuration is devised so that the position of the workpiece W can be grasped and gripped. This will be explained in detail below.

[0028] As a premise, the way in which the workpieces W are stacked on the pallet P, the shape of the workpieces W, the shape of the pallet P, etc. are all determined in advance. Then, the workpieces W, each having a predetermined shape, are stacked in a predetermined stacking manner on the pallet P, each having a predetermined shape.

[0029] To explain in more detail, in this embodiment, the shape of the workpiece W is a rectangular parallelepiped, and the length, width, and height dimensions of the workpiece W are all determined. The shape of the pallet P is a rectangular plate, and the length, width, and height dimensions (height from the ground) of the pallet P are all determined. Note that the dimensions of the pallet P may be changed as desired as long as it is rectangular. In other words, multiple types of pallets P with different dimensions may be used.

[0030] The way in which the workpieces W are stacked is also determined in advance. The way in which the workpieces W are stacked includes, for example, the number of tiers in the vertical direction, the number of workpieces W in each tier, the position of the workpieces W in each tier, the direction in which the workpieces W are placed, and the like. The position of the workpiece W is a three-dimensional coordinate based on the reference point P0. In other words, the position of the workpiece W is the relative position of the workpiece W with respect to the reference point P0. In this embodiment, the three-dimensional coordinate is the central position of the workpiece W, but it may be changed arbitrarily as long as the position can be grasped, and may be, for example, the position of a corner, or the position of a long side or short side.

[0031] When the position of the workpiece W is specified, a predetermined reference point P0 on the pallet P is used as a reference, and the position of the workpiece W is determined by aligning the length and width directions of the pallet P, i.e., the directions of two perpendicular sides, with the X-axis direction and the Y-axis direction. When the load Crg is palletized, it is arranged in one or more rows in two perpendicular directions. In this embodiment, when the load Crg is palletized, it is arranged in four rows in the X-axis direction and four rows in the Y-axis direction.

[0032] Furthermore, the direction in which the workpiece W is placed is information about which direction the long side of the workpiece W should face (for example, the X-axis direction or the Y-axis direction) if the workpiece W is rectangular. Note that if the shape of the workpiece W is cubic, this information is not necessary.

[0033] Furthermore, the arrangement (pallet pattern) of the workpieces W when stacked may be changed as desired, and may be, for example, any of blocked (flat stacking), brick stacking, pinhole stacking, window stacking, split stacking, etc. In this embodiment, pinhole stacking is used as shown in Fig. 3. The workpieces W are stacked at predetermined positions on the pallet P in a predetermined stacking manner by hand or a palletizing robot, etc.

[0034] However, when the workpieces W are stacked, they are placed on the pallet P so as to form a single block. Forming the workpieces W into a single block means, for example, arranging the workpieces W side by side so that they come into contact with adjacent workpieces W or so that the gap between adjacent workpieces W is a predetermined distance (e.g., 3 cm) or less.

[0035] 3, in this embodiment, the reference point P0 is a position where a first outer side C1 perpendicular to the X-axis direction and a second outer side C2 perpendicular to the Y-axis direction intersect at right angles among the outer sides of the load Crg, and where the load surface of the pallet P is placed. In other words, one of the lower corners of the load Crg is aligned with the reference point P0.

[0036] Then, the worker places the pallet P with the cargo Crg placed on it at a predetermined position determined for the depalletizing device 10 so that the reference point P0 set on the pallet P corresponds to the reference point P0 on the depalletizing device 10 and the length and width of the pallet P correspond to the X-axis and Y-axis directions on the depalletizing device 10.

[0037] Here, the predetermined position determined for the depalletizing apparatus 10 is determined, for example, by a frame line provided corresponding to the position of the depalletizing apparatus 10. Note that, instead of being limited to a frame line, a guide device may be used to guide the pallet P to the predetermined position. The worker places the pallet P in the predetermined position following the frame line or guide device. When the pallet P is placed in this predetermined position, as described above, the reference point P0 set on the pallet P corresponds (matches) with the reference point P0 determined in advance in the depalletizing apparatus 10, and the length and width of the pallet P correspond to the X-axis and Y-axis directions in the depalletizing apparatus 10.

[0038] The control device 100 of the depalletizing device 10 stores in advance information such as how to stack the workpieces W, the shape of the workpieces W, and the shape of the pallet P. That is, the control device 100 includes a storage device (such as a ROM or a RAM) as a storage unit that stores information such as the relative position of each workpiece W with respect to a reference point P0 during palletizing. When the pallet P on which the load Crg is placed is placed in a predetermined position, the control device 100 of the depalletizing device 10 specifies the position information of each workpiece W, such as the coordinates of the center position of the workpiece W, based on the contents stored in the storage device.

[0039] When depalletizing is performed, the control device 100 moves the chuck 20 based on the stored position information of the workpiece W with reference to the reference point P0, grips the workpiece W, and transports it to a discharge location, thereby performing depalletizing. At that time, it is desirable to pick up the placed workpieces W in order from the outside, more desirably from the corners.

[0040] However, the load Crg is not fixed on the pallet P. Therefore, when the load Crg is transported together with the pallet P, the load Crg may slip and become displaced on the pallet P. In other words, the load Crg may become displaced with respect to a reference point P0 set on the pallet P.

[0041] For this reason, even if the pallet P is placed in a predetermined position, since the load Crg is misaligned, if the reference point P0 is used as the reference, the position of the workpiece W cannot be accurately identified, and it may not be possible to properly grip the workpiece W. Therefore, before depalletizing, the amount of misalignment of the load Crg is detected and the reference point P0 is corrected.

[0042] When the pallet P is transported with the cargo Crg, the moving direction is generally along one of the sides of the pallet P. That is, when the pallet P is attached with casters and moved by a worker, or when it is transported by a transport vehicle such as a forklift or truck, it is generally moved along one of the sides of the pallet P in consideration of stability.

[0043] When the load Crg is displaced, it usually happens that the load Crg (as a whole load Crg) is displaced along the traveling direction when the acceleration changes suddenly at the start or stop of the movement. Therefore, in this embodiment, the displacement of the load Crg in the X-axis direction (horizontal direction of the pallet P) and the Y-axis direction (vertical direction of the pallet P) with respect to the pallet P is detected by the laser sensor 80, and the reference point P0 is corrected based on these displacements. The laser sensor 80 and the correction process will be described in detail below.

[0044] First, the laser sensor 80 will be described. As shown in FIG. 2, the laser sensor 80 is attached to the chuck 20 as a distance measuring sensor for measuring distance. The attachment position of the laser sensor 80 may be changed arbitrarily. As shown in FIG. 4, the laser sensor 80 includes a light emitting unit 81 that irradiates laser light and a light receiving unit 82 that receives the laser light reflected from the workpiece W or the like. The light emitting unit 81 and the light receiving unit 82 are arranged side by side at a predetermined distance, and the distance to the object is measured based on the time until the laser light irradiated from the light emitting unit 81 is reflected from the object such as the workpiece W and received by the light receiving unit 82 and the light receiving position. FIG. 4(b) is a schematic diagram showing a state in which the object is farther away from the laser sensor 80 than the state in FIG. 4(a). The laser sensor 80 is attached to the chuck 20 so that the laser light is irradiated directly below in the Z-axis direction. The laser sensor 80 is connected to the control device 100, and is configured to be able to input the distance in the vertical direction from the laser sensor 80 to the object.

[0045] Next, the correction process for detecting the position of the workpiece W and correcting the reference point P0 will be described in detail. The control device 100 executes a correction program stored in its storage device to perform the correction process shown in FIG. 5 below. Before depalletizing, the control device 100 detects the position of the workpiece W and performs the correction process shown in FIG. 5 to correct the reference point P0. The correction process is performed, for example, by an operator after the pallet P is placed in a predetermined position. Note that the correction process may also be performed by detecting the pallet P.

[0046] The control device 100 moves the chuck 20 horizontally in the X-axis direction above the workpiece W placed on the pallet P (above the Z-axis direction), thereby moving the laser sensor 80 horizontally, and during that time, measures the distance from the laser sensor 80 to an object such as the workpiece W (step S11).

[0047] The measurement in step S11 will be described in detail. FIG. 6 is a top view of the pallet P when the load Crg is viewed from above in the Z-axis direction. In FIG. 6, a reference point P0 set on the pallet P, and the X-axis and Y-axis based on the reference point P0 are illustrated. As a premise for the explanation, when the three-dimensional coordinates are (X, Y, Z), the three-dimensional coordinates of the reference point P0 are reference point P0 (0,0,0). In addition, in FIG. 6, the right side of the Y-axis based on the reference point P0 is the positive area in the X-axis direction, and the left side is the negative area in the X-axis direction, and the upper side of the X-axis based on the reference point P0 is the positive area in the Y-axis direction, and the lower side is the negative area in the Y-axis direction. In addition, it is assumed that the reference point P0 is set on the pallet P and each workpiece W is loaded so that the X-coordinate, Y-coordinate, and Z-coordinate are all in the positive area. Among the outer surfaces of the load Crg, in Fig. 6, the left side surface is the first outer surface C1, the lower side surface is the second outer surface C2, the right side surface is the third outer surface C3, and the upper side surface is the fourth outer surface C4. During palletizing, the corner where the first outer surface C1 and the second outer surface C2 intersect at right angles is aligned with the reference point P0, so Fig. 6 shows an example in which the position is shifted in the positive direction in the X-axis direction and the position is shifted in the positive direction in the Y-axis direction.

[0048] In step S11, the control device 100 moves the laser sensor 80 linearly in the X-axis direction (positive direction) at a position above the load Crg and at a predetermined distance from the reference point P0 in the Y-axis direction. Specifically, in three-dimensional coordinates, the laser sensor 80 is moved from a start point P1 (X1, Y1, Z1) to a relay point P2 (X2, Y1, Z1). Z1 is an arbitrary value, but it is preferable that it is, for example, a value within the measurement range of the laser sensor 80 and sufficiently larger than the height dimension of the load Crg. In addition, Y1 is an arbitrary value, but it is preferable that it is, for example, a value that takes into account the dimensions of the workpiece W and the expected amount of deviation. In this embodiment, Y1 is half the dimension in the Y-axis direction of the workpiece W1 (see FIG. 6) that is placed closest to the reference point P0.

[0049] X1 is also an arbitrary value, but it is preferable that the value takes into consideration, for example, an expected amount of deviation. In step S11, X1 is set to a negative value in order to scan from the outside to the inside of the pallet P, that is, from the outside to the inside of the workpiece W. For example, it is preferable that X1 is set within the range of values ​​estimated as the amount of deviation (-5 cm to -20 cm). Note that the range of values ​​estimated as the amount of deviation is appropriately changed depending on the material, weight, number, and stacking method of the workpiece W, and the material, size, transportation method, and transportation distance of the pallet P.

[0050] X2 is also an arbitrary value, but it is desirable that the value take into consideration, for example, the dimensions of the workpiece W and the expected amount of deviation. Furthermore, X2 is set to a positive value in order to scan from the outside to the inside of the pallet P, that is, from the outside to the inside of the workpiece W. In this embodiment, X2 is set to half the dimension in the X-axis direction of the workpiece W1 that is placed closest to the reference point P0. That is, when the control device 100 horizontally moves the laser sensor 80 in the X-axis direction, it moves it so as to pass through the position of the reference point P0 in the X-axis direction (i.e., X=0).

[0051] Then, in step S11, during this movement, the control device 100 sequentially measures and stores the distance in the Z-axis direction (up and down direction) from the laser sensor 80 to the object (e.g., workpiece W). Specifically, during the movement of the chuck 20 in step S11, the control device 100 stores the position coordinates of the chuck 20 for each time (hour), and measures the measured distance from the laser sensor 80 to the object for each time. Note that the time may be the elapsed time from the start point P1. FIG. 7 shows the measured distance from the laser sensor 80 to the object for each time. Note that in FIG. 7, the higher the position, the closer the distance to the laser sensor 80.

[0052] After scanning in the X-axis direction is completed in step S11, the control device 100 moves the chuck 20 horizontally in the Y-axis direction above the workpiece W placed on the pallet P, thereby moving the laser sensor 80 horizontally, while measuring (scanning) the distance from the laser sensor 80 to an object such as the workpiece W (step S12).

[0053] The scanning in step S12 will be described in detail. In step S12, the control device 100 moves the laser sensor 80 linearly in the Y-axis direction by a predetermined distance from the reference point P0 in the X-axis direction above the cargo Crg. In this embodiment, the laser sensor 80 is moved by a predetermined distance in the Y-axis direction (negative direction) from the coordinate at the time of completion of the scanning in step S11.

[0054] Specifically, the laser sensor 80 is moved from the intermediate point P2 (X2, Y1, Z1) to the end point P3 (X2, Y2, Z1). X2, Y1, and Z1 are as described in step S11. Y2 is an arbitrary value, but is preferably a value that takes into account, for example, an estimated amount of deviation. In addition, in step S12, Y2 is set to a negative value in order to scan from the inside to the outside of the pallet P, that is, from the inside to the outside of the workpiece W. For example, Y2 is preferably set within a range of a value (-5 cm to -20 cm) estimated as the amount of deviation. That is, when the control device 100 horizontally moves the laser sensor 80 in the Y-axis direction, the control device 100 moves the laser sensor 80 so as to pass through the position of the reference point P0 in the Y-axis direction (i.e., Y=0).

[0055] Also, in step S12, similarly to step S11, during movement, the control device 100 sequentially measures and stores the distance in the Z-axis direction from the laser sensor 80 to the target object (for example, the workpiece W) (see FIG. 7).

[0056] In addition, in steps S11 and S12, when the control device 100 moves the chuck 20 together with the laser sensor 80, the control device 100 rotates the chuck 20 by the rotation mechanism 23 so that the arrangement direction of the light-emitting unit 81 and the light-receiving unit 82 is perpendicular to the traveling direction of the laser sensor 80. In other words, the chuck 20 is rotated so that the light-emitting unit 81 and the light-receiving unit 82 move in a state where they are aligned side by side.

[0057] For example, as shown by the dashed line in Fig. 6, when moving in the X-axis direction in step S11, the control device 100 rotates the chuck 20 by the rotation mechanism 23 before moving in the X-axis direction so that the arrangement direction of the light emitter 81 and the light receiver 82 is perpendicular to the traveling direction (X-axis direction) of the laser sensor 80, that is, parallel to the Y-axis direction. The state at that time is shown by the laser sensor 80A in Fig. 6. Note that the laser sensor 80A is illustrated diagrammatically in Fig. 6 so that the arrangement direction can be easily recognized.

[0058] Similarly, when moving in the Y-axis direction in step S12 as shown by the dashed line in Fig. 6, the control device 100 rotates the chuck 20 in advance using the rotation mechanism 23 so that the arrangement direction of the light emitter 81 and the light receiver 82 is perpendicular to the traveling direction (Y-axis direction) of the laser sensor 80. The state at that time is shown by the laser sensor 80B in Fig. 6.

[0059] After step S12, the control device 100 scans the measurement result and detects the position coordinates where the measurement distance has changed by more than the threshold Th as the work ends Wa, Wb (step S13). The work ends Wa, Wb are parts corresponding to the outer edge of the work W when viewed from the Z-axis direction. More specifically, the work end Wa corresponds to the position of the first outer surface C1 of the outer surfaces of the load Crg in the X-axis direction, and the work end Wb is the position of the second outer surface C2 in the Y-axis direction. In step S13, in order to identify the outer edge of the work W in a planar view, the intersection point between the outer edge of the work W in a planar view and the movement trajectory of the laser sensor 80 is identified and detected as the work ends Wa, Wb. The intersection point between the outer edge of the work W in a planar view and the movement trajectory of the laser sensor 80 corresponds to the position coordinate at the timing when the detection value of the laser sensor 80 has changed by more than the threshold.

[0060] The method of detecting the workpiece ends Wa, Wb will be described in detail with reference to FIG. 7. In FIG. 7, the times T2, T3 at which the measured distance changes significantly by more than a predetermined threshold Th are considered to be the times at which the outer edge of the workpiece W, that is, the outer edge of the load Crg, is detected. Therefore, in step S13, the control device 100 identifies the times T2, T3 at which the measured distance changes significantly by more than a predetermined threshold Th. Then, the control device 100 identifies the position coordinates (X, Y, Z) of the chuck 20 corresponding to each of the times T2, T3, and determines the plane coordinates (X, Y) of the workpiece ends Wa, Wb from these position coordinates (X, Y, Z). The plane coordinates are the coordinates at the position of the reference point P0 (Z=0 in this embodiment) where the Z coordinate is the Z coordinate.

[0061] For example, the position coordinates (Xa, Ya, Za) of the chuck 20 (and the laser sensor 80) corresponding to time T2 are identified, and the planar coordinates (Xa, Ya) of the work end Wa are identified from these position coordinates (Xa, Ya, Za). From these X coordinates, the position of the first outer surface C1 in the X-axis direction can be identified. Note that the stored threshold value Th is used. Similarly, the position coordinates (Xb, Yb, Zb) of the chuck 20 corresponding to time T3 are identified, and the planar coordinates (Xb, Yb) of the work end Wb are identified from these position coordinates (Xb, Yb, Zb). From these Y coordinates, the position of the second outer surface C2 in the Y-axis direction can be identified.

[0062] Then, the control device 100 determines the amount of deviation of the reference point P0 based on the planar coordinates of the detected work ends Wa, Wb (step S14). In step S14, the control device 100 determines the distance from the reference point P0 to the detection position of the first outer side C1 in the X-axis direction as the deviation of the reference point P0 in the X-axis direction, and determines the distance from the reference point P0 to the detection position of the second outer side C2 in the Y-axis direction as the deviation of the reference point P0 in the Y-axis direction.

[0063] Specifically, the distance from the Y-axis (X=0) to the work end Wa in the X-axis direction is calculated, and the distance is identified as the deviation in the X-axis direction. For example, if the X-coordinate of the work end Wa is "Xa", "Xa" is taken as the deviation in the X-axis direction. Note that "Xa" may be either a positive or negative value. Similarly, the distance from the X-axis (Y=0) to the work end Wb in the Y-axis direction is calculated, and the distance is identified as the deviation in the Y-axis direction. For example, if the Y-coordinate of the work end Wb is "Yb", "Yb" is taken as the deviation in the Y-axis direction. Note that "Yb" may be either a positive or negative value.

[0064] Next, the control device 100 corrects the reference point P0 based on the identified amount of deviation (step S15). Specifically, (Xa, Yb, 0) is set as the corrected reference point P0'. Then, the correction process ends. As a result, the corrected reference point P0' coincides with the corner where the first outer side C1 and the second outer side C2 of the misaligned cargo Crg intersect at right angles. After the correction process, the control device 100 performs the depalletizing process using the corrected reference point P0' as a reference.

[0065] According to the above embodiment, the following effects can be obtained.

[0066] Before depalletizing, the control device 100 measures the distance from the laser sensor 80 to the target object while horizontally moving the laser sensor 80 above the load Crg placed on the pallet P, detects the positions of at least two orthogonal outer surfaces C1, C2 of the outer surfaces of the load Crg based on the measurement results, and corrects the horizontal position of the reference point P0 based on the positions of the two detected outer surfaces C1, C2. Specifically, the control device 100 detects the work ends Wa, Wb based on the measurement results, and corrects the position of the reference point P0 based on the detected work ends Wa, Wb. As a result, even if the position of the work W placed on the pallet P is shifted based on the reference point P0, the shift of the reference point P0 can be corrected by a simple correction process.

[0067] Therefore, in the depalletizing process, even if the chuck 20 is moved by the conveying mechanism 30 based on the central position coordinates (position information) of each work W stored in the memory device and using the corrected reference point P0' as a reference, the deviation has been corrected, so the chuck 20 can be moved to an appropriate position.

[0068] As described above, the position of the workpiece W can be identified and depalletized using a relatively simple configuration such as the laser sensor 80. In addition, since the workpiece ends Wa, Wb are determined based on the vertical distance to the target object measured by the laser sensor 80, the load can be reduced compared to image processing.

[0069] The control device 100 moves the laser sensor 80 horizontally along a predetermined first direction (X-axis direction), and then moves it horizontally in a second direction (Y-axis direction) perpendicular to the first direction. This makes it possible to correct the reference point P0 with a minimum of operations. This reduces the processing load, shortens the measurement time, and enables quick depalletizing.

[0070] The pallet P is rectangular, and the workpieces W are arranged in one or more rows along the two orthogonal sides of the pallet P. In this case, when considering the stability of the pallet P during transportation, it is common to move the pallet P in a direction along its sides (long side or short side). As for the pallet P, it is common to move it in the X-axis or Y-axis direction. For this reason, it is considered that the workpieces W placed on the pallet P also usually shift (move) in the traveling direction along the sides of the pallet P, and the load Crg also shifts as a unit parallel to the X-axis or Y-axis direction.

[0071] Therefore, the control device 100 moves the laser sensor 80 horizontally from the outside to the inside of the pallet P along a first direction (in this embodiment, the X-axis direction) parallel to any one of the four sides that constitute the pallet P positioned at a predetermined position relative to the depalletizing device 10 (step S11), and then moves the laser sensor 80 horizontally from the inside to the outside of the pallet P along a second direction (the Y-axis direction) perpendicular to the first direction to measure the distance.

[0072] As a result, the control device 100 can detect the position of the first outer surface C1 in the X direction (i.e., the workpiece end Wa) from the measurement results when the laser sensor 80 is moved horizontally in the X axis direction, and can detect the position of the second outer surface C2 in the Y direction (i.e., the workpiece end Wb) from the measurement results when the laser sensor 80 is moved horizontally in the Y axis direction.

[0073] In addition, in this embodiment, the position of the reference point P0 in the horizontal direction is determined to coincide with the position where the first outer side C1 and the second outer side C2 of the cargo Crg intersect. Therefore, when the control device 100 horizontally moves the laser sensor 80 in the X-axis direction, the control device 100 can reliably detect the first outer side C1 by moving the laser sensor 80 so as to pass through the position of the reference point P0 in the X-axis direction (i.e., X=0). Similarly, when the control device 100 horizontally moves the laser sensor 80 in the Y-axis direction, the control device 100 can reliably detect the second outer side C2 by moving the laser sensor 80 so as to pass through the position of the reference point P0 in the Y-axis direction (i.e., Y=0). Therefore, the moving distance of the laser sensor 80 can be shortened compared to when detecting outer sides other than the first outer side C1 and the second outer side C2.

[0074] In addition, the control device 100 specifies the distance from the reference point P0 to the detection position of the first outer side C1 in the X-axis direction (i.e., Xa) as the deviation of the reference point P0 in the X-axis direction, and specifies the distance from the reference point P0 to the detection position of the second outer side C2 in the Y-axis direction (i.e., Yb) as the deviation of the reference point P0 in the Y-axis direction, thereby correcting the deviation of the reference point P0. That is, the control device 100 assumes that the deviation occurs in either the X-axis direction or the Y-axis direction along the side of the pallet P, moves the laser sensor 80 along the X-axis direction, detects the work end Wa from the measurement result, and specifies the deviation amount "Xa" in the X-axis direction from the planar coordinates (Xa, Ya) of the work end Wa. Similarly, the laser sensor 80 moves along the Y-axis direction, detects the work end Wb from the measurement result, and specifies the deviation amount "Yb" in the Y-axis direction from the planar coordinates (Xb, Yb) of the work end Wb. Then, the control device 100 corrects the reference point P0 based on the amount of deviation "Xa" in the X-axis direction and the amount of deviation "Yb" in the Y-axis direction. As described above, since it is assumed that there is a deviation in either the X-axis direction or the Y-axis direction, it is possible to specify the amount of deviation with simple control and simple processing.

[0075] In addition, since the pallet P is moved in the X-axis direction (the positive side in the X-axis direction) and then moved in the Y-axis direction to the outside of the pallet P (the negative side in the Y-axis direction), it is possible to perform continuous measurements from the start point P1 to the end point P3 via the relay point P2. This shortens the moving distance and the detection time. In addition, since the outer edge of the cargo Crg that is close to the X-axis or Y-axis is detected, the measurement distance can be shortened compared to when an outer edge far from the X-axis or Y-axis is detected.

[0076] The laser sensor 80 is attached to the chuck 20. The control device 100 controls the transport mechanism 30 to horizontally move the chuck 20 above the workpieces W loaded on the pallet P. This causes the laser sensor 80 to move horizontally. Thus, even if a special mechanism for moving the laser sensor 80 is not provided, by attaching the laser sensor 80 to the chuck 20, the transport mechanism 30 of the chuck 20 can be used.

[0077] The laser sensor 80 cannot measure the distance if the laser light to the light receiving unit 82 is blocked. Therefore, when the laser sensor 80 is moved horizontally to measure the distance in the Z-axis direction, if the arrangement direction of the light emitting unit 81 and the light receiving unit 82 is aligned with the traveling direction of the laser sensor 80 as shown in FIG. 8(a), there is a high possibility that the distance cannot be accurately measured due to the workpiece W blocking the laser light as shown in FIG. 8(b). Therefore, when measuring the distance with the laser sensor 80, the control device 100 moves the laser sensor 80 in a direction perpendicular to the arrangement direction of the light emitting unit 81 and the light receiving unit 82 as shown in FIG. 6. This prevents the laser light from being blocked by the workpiece W, and enables accurate measurement.

[0078] When the control device 100 changes the traveling direction of the laser sensor 80 during distance measurement, the control device 100 rotates the laser sensor 80 so that the arrangement direction of the laser sensor 80 is perpendicular to the traveling direction of the laser sensor 80. This makes it possible to prevent the laser light from being blocked by the workpiece W even when the traveling direction is changed. In addition, the rotation mechanism 23 of the chuck 20 is also used to rotate the laser sensor 80. Therefore, there is no need to provide a rotation unit dedicated to the laser sensor 80.

[0079] During distance measurement by the laser sensor 80, the position coordinates of the chuck 20 for each time are stored, and the measurement results of the laser sensor 80 for each time are stored, and later, the position coordinates and the measurement results are associated with each other based on the time. This allows the laser sensor 80 to be externally attached to the chuck 20, and the position of the workpiece W can be detected with a simple configuration.

[0080] (Modification) Below, modifications in which the configurations of the above-described embodiments are partially changed will be described.

[0081] In the above embodiment, the height dimension of the pallet P (height from the ground to the top surface of the pallet P) may be changed arbitrarily. In this case, it is necessary to correct the amount of deviation of the reference point P0 in the Z-axis direction in the correction process. Specifically, the control device 100 measures the distance to the top surface of the pallet P (the surface on which the workpiece W is placed) to identify the amount of deviation in the Z-axis direction, and corrects the deviation of the reference point P0 in the Z-axis direction.

[0082] In the above embodiment, it is not necessary to rotate the chuck 20 when changing the direction of travel of the laser sensor 80. This can reduce time.

[0083] In the above embodiment, a convex portion protruding from the inner side surface 41a of the support piece 41 may be provided on the inner side surface 41a instead of the second suction pad 44. Also, a cushioning material such as rubber, a spring, or a sponge may be provided.

[0084] In the above embodiment, the support piece 41 does not have to be formed in a flat plate shape. For example, it may be formed in a claw shape, with the side surface supported by a plurality of claws.

[0085] In the above embodiment, the configuration of the suction pads 26, 44 may be changed as desired. For example, the suction pads 26, 44 may use a sponge material in the portion that comes into contact with the workpiece W.

[0086] In step S13 of the above embodiment, the position coordinates at the timing when the measured distance has changed by a predetermined threshold value Th or more are detected as the work ends Wa, Wb. As another example, the distance Z10 to the top surface of the work W may be specified, and the position coordinates at the timing when the measured distance has increased from the distance Z10 by a predetermined threshold value Th or more, or the position coordinates at the timing when the measured distance has reached the distance Z10 from a distance that is a predetermined threshold value Th or more away from the distance Z10, may be determined as the work ends Wa, Wb.

[0087] In the above embodiment, the coordinates of the center position of each workpiece W are stored as the position information, but the content of the position information may be changed arbitrarily as long as each workpiece W can be gripped by the chuck 20. For example, for each workpiece W, the moving direction and moving distance of the chuck 20 based on the reference point P0 may be stored as the position information of each workpiece W. Then, when depalletizing, these may be read out and the chuck 20 may be moved.

[0088] In the above embodiment, the laser sensor 80 is used as the distance measuring sensor, but the sensor may be changed to any other sensor capable of measuring distance. For example, an ultrasonic sensor or a TOF sensor may be used.

[0089] In the above embodiment, the configuration of the transport mechanism 30 for the chuck 20 may be changed as desired in the depalletizing device 10. For example, the chuck 20 may be configured to be movable by a multi-joint arm.

[0090] In the above embodiment, the positions of the outer surfaces of the cargo Crg other than the outer surfaces C1 and C2 may be stored, and the positions of the outer surfaces other than the outer surfaces C1 and C2 may be detected and compared to identify the deviation of the reference point P0. For example, the control device 100 may store the position coordinate "X3" of the third outer surface C3 (see FIG. 6) in the X-axis direction, detect the coordinate of the third outer surface C3 in the X-axis direction before depalletizing, and compare them to correct the deviation of the reference point P0 in the X-axis direction. Similarly, the control device 100 may store the position coordinate "Y4" of the fourth outer surface C4 (see FIG. 6) in the Y-axis direction, detect the coordinate of the fourth outer surface C4 in the Y-axis direction before depalletizing, and compare them to correct the deviation of the reference point P0 in the Y-axis direction. [Explanation of symbols]

[0091] 10...depalletizing device, 20...chuck, 23...rotation mechanism, 30...transport mechanism, 80...laser sensor, 81...light emitting unit, 82...light receiving unit, 100...control device, Crg...load, P...pallet, W...workpiece, Wa, Wb...workpiece end.

Claims

1. In a work transport device that depalletizes a group of workpieces in which a plurality of workpieces are placed on a pallet as a group, When the workpieces constituting the work group are palletized, they are arranged in one or more rows in two orthogonal directions, and the relative position of each workpiece is determined in advance with respect to a reference point set on the pallet; A chuck portion that grips the workpiece; A moving unit that moves the chuck unit; A storage unit that stores relative position information of each workpiece during palletizing with respect to the reference point; a calculation processing device that controls the chuck unit and the moving unit so that, when performing the depalletizing, the chuck unit is moved by the moving unit based on the position information of each workpiece stored in the memory unit, and then the chuck unit grips the workpiece; A distance measuring sensor for measuring a distance, The calculation processing device is a work transport device that, before performing the depalletizing, measures the vertical distance to the target object by moving the distance measuring sensor horizontally above the group of works placed on the pallet, detects the positions of at least two perpendicular outer surfaces among the outer surfaces of the group of works based on the measurement results, and corrects the horizontal position of the reference point based on the detected positions of the two outer surfaces.

2. The workpiece transport device according to claim 1 , wherein the arithmetic processing device horizontally moves the distance measuring sensor along a predetermined first direction, and then horizontally moves the distance measuring sensor in a second direction perpendicular to the first direction.

3. The pallet is rectangular in shape, The workpieces constituting the work group are arranged in one or more rows along the directions of two perpendicular sides of the pallet, A position at which the pallet is placed with respect to the workpiece transport device is determined in advance, The work transport device of claim 1, wherein the arithmetic processing device measures the distance by horizontally moving the distance measuring sensor from the outside to the inside of the pallet along a first direction parallel to any one of the four sides that constitute the pallet positioned relative to the work transport device before performing the depalletizing, and then measures the distance by horizontally moving the distance measuring sensor from the inside to the outside of the pallet along a second direction perpendicular to the first direction.

4. The arithmetic processing device includes: From the measurement results when the distance measuring sensor is moved horizontally in the first direction, a position in the first direction of a first outer surface of the outer surface of the work group that is perpendicular to the first direction is detected, and from the measurement results when the distance measuring sensor is moved horizontally in the second direction, a position in the second direction of a second outer surface of the outer surface of the work group that is perpendicular to the first outer surface is detected. A workpiece transport device as described in claim 3, wherein the position of the first outer surface in the first direction stored in the memory unit is compared with the detected position of the first outer surface to correct the deviation of the reference point in the first direction, and the position of the second outer surface in the second direction stored in the memory unit is compared with the detected position of the second outer surface to correct the deviation of the reference point in the second direction.

5. The position of the reference point in the horizontal direction is predetermined so as to coincide with a point where a first outer surface of the outer surface of the workpiece group that is perpendicular to the first direction intersects with a second outer surface of the outer surface of the workpiece group that is perpendicular to the first outer surface, The work transport device of claim 3, wherein when the arithmetic processing device moves the distance measuring sensor horizontally in the first direction, it moves it so that it passes through the position of the reference point in the first direction, and when the arithmetic processing device moves the distance measuring sensor horizontally in the second direction, it moves it so that it passes through the position of the reference point in the second direction.

6. The arithmetic processing device includes: a position of the first outer surface in the first direction is detected from a measurement result obtained when the distance measuring sensor is moved horizontally in the first direction, and a position of the second outer surface in the second direction is detected from a measurement result obtained when the distance measuring sensor is moved horizontally in the second direction; A workpiece transport device as described in claim 5, wherein in a first direction, the distance from the reference point to the detection position of the first outer surface is identified as the deviation of the reference point in the first direction, and in a second direction, the distance from the reference point to the detection position of the second outer surface is identified as the deviation of the reference point in the second direction, thereby correcting the deviation of the reference point.

7. A work transport device described in any one of claims 1 to 6, wherein the calculation processing device measures the distance from the distance measuring sensor to the pallet before performing the depalletizing, and corrects the position of the reference point in the vertical direction based on the measurement result.

8. The distance measuring sensor is attached to the chuck portion, A work transport device described in any one of claims 1 to 6, wherein the calculation processing device controls the moving unit to move the chuck portion horizontally above the work loaded on the pallet, thereby moving the distance measuring sensor horizontally.

9. The distance measuring sensor is a laser sensor having a light emitting unit that irradiates a laser beam and a light receiving unit that receives the laser beam reflected from a workpiece, The light emitting unit and the light receiving unit are arranged side by side in a predetermined arrangement direction, The workpiece transport device according to any one of claims 1 to 6, wherein the arithmetic processing device moves the laser sensor in a direction perpendicular to an arrangement direction of the light emitting unit and the light receiving unit when scanning the workpiece.

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