Paretize and Deparetize Grippers, Systems, and Methods

Abstract

The present invention relates to a gripper (300) intended to be mounted on a robot (200) of a loading / unloading system for gripping a package (400) that is moved from or to a container when actuated. The gripper (300) comprises a frame (310), and the frame (310) carries a plurality of gripping devices (301) each having a first end attached to the frame (310) and a second end carrying a suction cup (303), the suction cup being connected to a vacuum device (305). According to the invention, - each suction cup (303) can be individually actuated to grip the package (400) by suction, - the gripping device (301) is movable relative to the frame and comprises a linear shaft (302) capable of moving the suction cup (303) of the device (301) between a retracted position and a forward position. The present invention also relates to a small load loading / unloading system using this gripper, and a method of using this system.

Description

Technical Field

[0001] The present invention belongs to the field of intralogistics and relates to grippers and palletizing / depalletizing systems. The present invention further relates to a method for automatically unloading small packages using such a system.

Background Art

[0002] Known palletizing / depalletizing systems use robots to install or remove a set of packages in a specific order.

[0003] Packages (or small packages) can be any type of regularly shaped object that can be transported in the form of a container, such as a cube or rectangular box, or goods, such as a set of bags or bottles held together by a plastic film.

[0004] The container can be, for example, a pallet, a roll cart, or a crate.

[0005] In known depalletizing systems, a pallet containing a set of packages arranged in stacked layers is supplied to the unloading station. A robot equipped with a gripper picks up the package by suction and then moves the package to a receiving area such as a conveyor, and is configured to contact the package in order to drop the package. The gripper can also pick up two or more items at a time. This operation is often difficult to handle when the packages are of variable size and when the system does not know in advance the dimensions of the packages to be unloaded. Visual and related computing systems estimate the time required to pick up and drop the package in order to limit the risk of impact.

[0006] However, when the package does not appear in its normal position, for example, when it is tilted during loading or follows the movement of the container, if the gripper used is a normal one, there is a risk of damage to the package. In this case, the method can be interrupted to manually pick up the tilted package or return it to its normal position, enabling the robot to continue loading or unloading.

[0007] Therefore, it is necessary to find an automatic solution to avoid the risk of damaging such packages arriving in a tilted position or to avoid wasting valuable time every time the system detects a package in an abnormal position.

[0008] Therefore, an object of the present invention is to provide a palletizing and / or depalletizing system that solves the above problems.

Summary of the Invention

[0009] To achieve this object, according to a first aspect, the present invention relates to a gripper intended to be mounted on a robot of a loading / unloading system for gripping packages that are moved from or to a container when actuated. The gripper comprises a frame, and the frame carries a plurality of gripping devices each having a first end attached to the frame and a second end carrying a suction cup. The suction cup is connected to a vacuum device.

[0010] According to the present invention, - each suction cup can be individually actuated to grip the package by suction, - the gripping device is movable relative to the frame and comprises a linear shaft capable of moving the suction cup of the gripping device between a retracted position and a forward position.

[0011] Advantageously, two or more gripping devices each comprise a respective movable linear shaft. In some embodiments, each gripping device comprises a movable linear shaft.

[0012] By moving one or more suction cups, it is possible to adapt the pick-up position of the gripper to the position of the inclined package.

[0013] Advantageously, the linear shaft may be a hollow cylinder (also called a plunger) having an upper end connected to a vacuum device, for example in the form of a ball screw, and a lower end carrying the suction cup.

[0014] The hollow cylinder enables fluid connection to the vacuum device without the need for additional piping, thus reducing space requirements and maintenance and increasing robustness.

[0015] Advantageously, the gripping device comprises a ball joint connecting the suction cup to the cylinder.

[0016] Thanks to the ball joint, the suction cup can be adapted to the inclination of the package, ensuring good gripping by suction.

[0017] Advantageously, the gripping device comprises correction means configured to cooperate with the ball joint in order to return the position of the suction cup relative to the linear shaft. This makes it possible to correct the position of the small load to a position that facilitates installation onto the container or receiving area. This also makes it possible to orient the suction cup in a regular orientation, for example horizontally, at least in the retracted position.

[0018] Advantageously, the gripping device may comprise an annular motor through which the linear shaft passes, the motor being configured to move the linear shaft in order to guide the suction cup from the retracted position to the advanced position (and vice versa).

[0019] This results in a compact gripper. This is because it does not require a belt or gear transmission, which significantly reduces the space occupied by each gripping device.

[0020] Advantageously, the gripping device may comprise an encoder configured to measure the position of the linear shaft and transmit it to control means external to the gripper.

[0021] This enables the control means to infer the position of the suction cup in the space and control its movement by means of the moving means, for example by means of an annular motor.

[0022] Advantageously, the gripping device may comprise a brake that can be controlled to lock the linear shaft in a specific position of the suction cup. For example, the brake can be activated to lock the linear shaft when the motor is not powered, to save energy and prevent overheating of the motor. Thus, the brake ensures the integrity of the gripping device and the package being moved.

[0023] The control means comprises, for example, an inverter that can drive the motor, receive information from the encoder and also control the brake.

[0024] Advantageously, a plurality of gripping devices may be arranged in two parallel rows that can be moved relative to each other so that the distance between them can be changed according to the size of the package to be gripped.

[0025] This enables the lifting operation of the gripper to be adapted along the first direction of the package, for example, to adapt it to the width of the package. This also enables the devices in the second row to be deactivated if the lifting can be done by the first row only.

[0026] Advantageously, the row may comprise two gripping devices separated by a distance that can be changed according to the dimensions of the package to be gripped.

[0027] This enables the lifting operation of the gripper to be adapted along the second direction, for example, to adapt it to the length of the package. This also enables the devices within the same row that are not involved in lifting the package to be separated.

[0028] The present invention further relates to a loading or unloading system comprising a gripper as described above.

[0029] Advantageously, the loading / unloading system according to the present invention as described above may further comprise visual means capable of detecting tilted small packages, and control means capable of controlling the movement of at least one suction cup according to the tilt of the small package inferred from the information transmitted by the visual means.

[0030] The present invention also relates to a depalletizing or palletizing method in which packages are unloaded from or loaded onto a container using a unloading or loading system as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Further features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings, which are given by way of non-limiting example, where

Figure 1

Figure 2

Figure 3

Figure 4

[0032] FIG. 1 schematically depicts in part a system 1 for loading or unloading a package 4 according to a first embodiment of the present invention. The system 1 comprises a robot 2 equipped with a gripper 3 according to the present invention.

[0033] The container from which the package 4 is taken out is not shown, but it may be, for example, a pallet or a roll cart. Such a container may contain a set of packages 4, for example, parcels of non-uniform shape and size. They may also be partially or wholly uniform. Some of the packages 4 appear tilted, for example, as a result of transportation.

[0034] In this situation, a type of palletizing / depalletizing system known from the prior art has to be stopped in order to enable the manual picking up of the tilted packages, which is a considerable waste of time.

[0035] To solve this problem, the gripper 3 according to the invention as shown in FIG. 1 comprises a plurality of gripping devices 31 carried by a frame 30. By way of example, the number of gripping devices 31 may be eight as shown in FIG. 1, but in embodiments not shown, the number may be different.

[0036] Each device 31 comprises a suction cup 33 connected to a vacuum device (not shown in FIG. 1). The suction cup 33 is used to grip the parcel 4 or a part thereof by suction, as shown in FIG. 1. In order to enable the gripping of a tilted parcel, as in the case of the parcel 4, the gripping device 31 has a linear shaft 32 that can be moved relative to the frame 30. For example, in FIG. 1, the eight gripping devices 31 each comprise a movable linear shaft 32 that can move its respective suction cup 33 in accordance with the tilt of the parcel 4.

[0037] The linear shaft may be in the form of a tube or a cylinder arranged to slide in order to move the suction cup 33 a given distance relative to the frame 30.

[0038] To control the gripper 3 and the gripping device 31, the system 1 may comprise, for example, visual means capable of detecting the inclination of the package 4. The system may further comprise control means such as software that can process the information received from the visual means and control the movement of the suction cup 33 according to the determined inclination. The software can also control the movement of the parcel 4 after being gripped by the suction cup.

[0039] Figure 2 shows a second example of a loading / unloading system 100 comprising a robot 200 equipped with a gripper 300 that carries a frame 310 supporting a gripping device 301.

[0040] This loading / unloading system operates in the same manner as the system shown in Figure 1.

[0041] Similar to the system 1 described above, the system 100 may comprise visual means capable of detecting the inclination of the package 400. The system 100 may further comprise control means such as software that can process the information received from the visual means and control the movement of the suction cup 303 according to the determined inclination. The software can also control the movement of the parcel after being gripped by the suction cup.

[0042] A special feature of the system 100 shown in Figure 2 is that the gripper 300 is much more compact due to the shape of the gripping device 301. Two lamps 304A, B are attached to the frame 310, each carrying a plurality of gripping devices 301, for example four of them.

[0043] Advantageously, the two lamps 304A, B can be moved relative to each other so that the distance between them can be changed according to the size of the package 400 to be gripped.

[0044] Advantageously, within the same column, at least two gripping devices 301 are separated by a distance that can be varied according to the dimensions of the package to be gripped. For example, the lamp 304A can be controlled so as to widen or narrow the distance between each two gripping devices 301.

[0045] Figure 3 shows the device 301 of the gripper 300 in the retracted position P1 and the advanced position P2. Figure 4 shows a cross-sectional view of zone IV shown in Figure 3.

[0046] As can be seen from the drawings, the gripping device 301 is compact and generally cylindrical. At the upper part, a hollow rod 311 is connected to a vacuum block 305 (referred to as a Venturi block), and the tube providing the connection is not shown in Figure 3. At the lower part, a linear shaft in the form of a hollow cylinder 302 can slide with respect to the tube 311 without losing the seal. The cylinder 302 (also known as a plunger) is, for example, a ball screw. The shaft 302 carries a suction cup 303 at the bottom. Advantageously, the suction cup 303 can be connected to the cylinder 302 by a ball joint 312. Thereby, the position of the suction cup can be adapted to the inclination of the package 400.

[0047] Such a ball joint can also be associated with the embodiment shown in Figure 1.

[0048] In the central part, the gripping device 301 can include an annular motor 306 through which a linear shaft 302 (a ball screw in this example) passes. The motor can be driven to move the shaft 302 in order to guide the suction cup from position P1 to position P2 (and vice versa).

[0049] Compared with the previous example, this motor has the advantage of not requiring a belt or a gear transmission, which greatly reduces the space occupied by each gripping device 301. Thanks to this motor, the gripper is very compact.

[0050] The gripping device 301 may further include an encoder 307 and a brake 308, which are also annular in the examples shown in FIGS. 2 to 4. The encoder enables the position of the linear shaft 302 to be measured at any time and transmitted to the control unit. The brake 308 can be controlled to lock the linear shaft at a specific position of the suction cup 303.

[0051] The control means includes, for example, an inverter that can drive the motor, receive information from the encoder, and control the brake.

[0052] The loading or unloading cycle using the above-described system may include some or all of the following steps: A container such as a pallet is supplied to the loading / unloading station by a conveyor.

[0053] The container is placed on the lift table in any manner.

[0054] The detection means detects small items located at the top, and transmits an image to the control system. The control system determines the topmost small item to be picked up first by the gripper. The control device can select the number of gripping devices involved in picking up the small item according to the dimensions of the small item.

[0055] The interval between the gripping devices 301 can be adjusted according to the size of the package and the number of gripping devices 301 involved. If the topmost small item is tilted, the control means controls the motors of one or more of the gripping devices 31, 301 to move the respective suction cups according to the tilt of the small item. The gripper descends to pick up the small item, then ascends again, and the suction cup is moved to the retracted position P1, so that the small item becomes horizontal and is ready to be moved to the receiving area.

[0056] These steps are repeated for all packages.

Claims

1. A gripper (3,300) intended to be mounted on a loading / unloading system robot (2,200) for gripping packages (4,400) from or being moved into a container when activated, the gripper (3,300) comprises a frame (30,310), the frame (30,310) carrying a plurality of gripping devices (31,301), each having a first end attached to the frame (30,310) and a second end carrying a suction cup (33,303), the suction cup being connected to a vacuum device (305), - Each suction cup (33, 303) may be operated individually to grip the package (4, 400) by suction. - The gripping device (31, 301) is movable relative to the frame and includes a linear shaft (32, 302) that can move the suction cup (33, 303) of the gripping device (31, 301) between a retracted position (P1) and an advanced position (P2), The gripper (3, 303) is characterized in that the gripping device (301) comprises an annular motor (306) through which the linear shaft (302) passes, and the motor (306) is configured to move the linear shaft (302) to guide the suction cup (303) from the retracted position (P1) to the forward position (P2) (and vice versa).

2. The gripper (3, 300) according to claim 1, wherein the linear shaft (302) is a hollow cylinder having an upper end connected to the vacuum device (305) and a lower end supporting the suction cups (33, 303).

3. The gripper (3, 300) according to claim 2, wherein the gripping device comprises a ball joint (312) connecting the suction cup to the cylinder (302).

4. The gripper (300) according to claim 3, further comprising a corrective means configured to cooperate with the ball joint (312) to return the position of the suction cup (303) relative to the linear shaft.

5. The gripper (3, 300) according to any one of claims 1 to 4, wherein the gripping device (31, 301) includes an encoder (307) configured to measure the position of the linear shaft and transmit it to an external control means of the gripper.

6. The gripper (3, 300) according to claim 1, wherein the gripping device (31, 301) is equipped with a brake (308) that can be controlled to block the linear shaft (32, 302) according to a specific position of the suction cup (33, 303).

7. The gripper (3, 300) according to claim 1, wherein the plurality of gripping devices (31, 301) are arranged in two parallel rows that can be moved relative to each other so that the distance between them can be changed according to the size of the package (4, 400) to be gripped.

8. The gripper (3,300) according to claim 7, comprising two gripping devices (31, 301) separated by a distance that can be changed based on the dimensions of the package (4, 400) to be gripped.

9. A loading or unloading system (1, 100) comprising the gripper (3, 300) described in Claim 1.

10. The unloading or loading system (1,100) according to claim 9, further comprising: a visual means capable of detecting a tilted package (4,400); and a control means capable of controlling the movement of at least one suction cup (33,303) in accordance with the tilt of the package (4,400) inferred from information transmitted by the visual means.

11. A depalletizing or palletizing method wherein the package (4,400) is unloaded from or loaded into a container using the unloading or loading system (1,100) described in claim 9.

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