Positioning device and method for positioning a flexible, flat workpiece - Patent Application 20070122997

Abstract

A positioning device (10) for positioning a flexible, flat workpiece (12) is described. The device includes a presentation area (18) for providing the flat workpiece (12) to be positioned, and a camera (22) for generating a camera image (B) of the flat workpiece (12) to be positioned. The positioning device (10) further includes a first manipulator (26) having a first gripper (28). A second gripper (58) and a third gripper (60) are also provided. The second gripper (58) and the third gripper (60) are configured to take over at least a portion of the flexible, flat workpiece (12) from the first gripper (28). A method for positioning a flexible, flat workpiece (12) is also presented.

Description

[Technical Field]

[0001] The present invention relates to a positioning device for positioning a flexible, flat workpiece.Furthermore, the present invention relates to a method for positioning a flexible, flat workpiece. [Background technology]

[0002] In this context, a flat workpiece is understood to mean a workpiece that can have a planar or sheet-like shape, i.e., for example, in the form of a mat or a sheet or a film, and thus has one dimension that is significantly smaller than the other two dimensions.

[0003] In this context, a flexible workpiece is one that is subject to large deformations under the action of relatively small forces and / or moments. Flexible workpieces are also referred to as dimensionally unstable or dimensionally unstable.

[0004] Flexible, flat workpieces are found in many areas of industrial application, including the production of textiles, especially clothing textiles, industrial laundries, the manufacture of vehicle and aircraft covers and linings, and the manufacture of components made from fiber composites.

[0005] In the above application fields, a common problem here is the need to transfer flexible, flat workpieces from a random, in particular randomly or irregularly folded state to a predetermined position, for example for machining or processing, which often involves bringing the flexible, flat workpiece into a flat, unfolded position.

[0006] In many of the above applications, it is common practice to manually transport flat workpieces to these predetermined locations.

[0007] Automated methods for this are also known, which are usually based on the function principle of multiple re-gripping, which means that the flat workpiece is gripped several times at different points, in particular three or more times, in order to transfer it to the desired position. Summary of the Invention [Problem to be solved by the invention]

[0008] Against this background, the object of the present invention is to show a positioning device and method for positioning a flexible, flat workpiece, which allows the flexible, flat workpiece to be transferred in a simple, fast and reliable way to a desired final state, regardless of its random initial state. [Means for solving the problem]

[0009] This object is achieved by a positioning device for positioning a flexible, flat workpiece, including a provision area for providing the flexible, flat workpiece to be positioned. A camera is further provided, positioned and configured to generate a camera image of the flexible, flat workpiece to be positioned in the provision area. The positioning device further includes a first manipulator carrying a first gripper configured to grasp at least a portion of the flexible, flat workpiece from the provision area. The positioning device is further equipped with a second gripper and a third gripper, each configured to take over at least a portion of the flexible, flat workpiece from the first gripper.

[0010] In a first alternative, the second gripper and the third gripper are drivingly connected to a linear drive unit, the second gripper and the third gripper each being movable along the linear drive unit.

[0011] In a second alternative, the second gripper is carried by the second manipulator and the third gripper (60) is carried by the third manipulator (54b). The second and third manipulators may be industrial robots that cooperate with each other to handle flat workpieces.

[0012] The designations "first," "second," and "third" gripper and "first," "second," and "third" manipulator are used for clarity only and do not refer to any particular number of grippers or manipulators.

[0013] Furthermore, in the first alternative the linear drive unit to which the second and third grippers are drivingly connected is separate from the first manipulator.

[0014] Using the provision area, flexible, flat workpieces that are positioned and available randomly, in particular in an irregularly folded state, can be provided in a simple manner for further processing. From there, the flat workpiece to be positioned is removed by a first gripper, i.e., the first gripper grips a portion of the flat workpiece. For this purpose, edges that can be successfully gripped by the first gripper can be identified by a camera, so that the first gripper can grip the flat workpiece from the provision area reliably and quickly.

[0015] The flat workpiece can then be transferred to the second and third grippers, where in particular the second and third grippers are movable independently of each other along the direction of movement of the linear drive unit. In an alternative where the second and third grippers are held by the second and third manipulators, respectively, the grippers can move almost freely in space. In both alternatives, the flat workpiece gripped by the second and third grippers can be transferred to a flattened position in a simple, fast and reliable manner.

[0016] The linear drive unit and also the second and third manipulators are configured, for example, to deposit a flat workpiece gripped by the second and third grippers in a predetermined manner and / or to place it in a downstream processing machine in a predetermined manner.

[0017] This means that the positioning device is generally designed so that a flat workpiece is transferred inside the positioning device only once. In other words, only one re-gripping process is performed. On the one hand, this provides a simple and compact structure for the positioning device. On the other hand, this allows a flat workpiece to be transferred from a random initial state to a target state, which in particular corresponds to a flat, spread-out state, at high speed. In other words, such a positioning device can transfer a flexible, flat workpiece to a target state in a short cycle time.

[0018] The flat workpieces are, for example, towels, pillows, napkins, bed linen, incontinence pads or tablecloths. More commonly, the flat workpieces are flat linen or terry cloth products.

[0019] In this context, the edge of a flat workpiece is understood to mean the boundary of the flat workpiece, which may be hemmed or unhemmed.

[0020] The linear drive unit, together with the second and third grippers, is mounted within the positioning device and is rotatable about an axis extending parallel to the longitudinal extent of the positioning device. In particular, the linear drive unit is mounted on a rack or frame of the positioning device.

[0021] The linear drive unit has one dimension significantly larger than the other two. The direction of the longitudinal extent corresponds to this significantly larger dimension. Furthermore, the longitudinal extent coincides with the direction of movement of the linear drive unit, i.e., the direction in which the second and third grippers can move. For simplicity's sake, the linear drive unit is sometimes referred to as a linear motion slide, since it can be used to move the second and third grippers linearly. Because the linear drive unit is mounted to rotate, the second and third grippers can be oriented relative to the flat workpiece so that they can securely grip it, taking over from the first gripper. Furthermore, the rotatable mounting allows the positions of the second and third grippers to be adapted to the orientation of the base or machine section on which the flat workpiece is to be placed during the process of placing the flat workpiece. This allows the flat workpiece to be positioned particularly accurately and reliably. Furthermore, the flat workpiece can be placed while the linear drive unit rotates with the second and third grippers. This results in a particularly gentle, crease-free, or at least wrinkle-free, flat workpiece placement. Naturally, the same result can be achieved if the second gripper is held by the second manipulator and the third gripper is held by the third manipulator. The second and third manipulators then move the second and third grippers in the directions described above.

[0022] In one alternative, the providing area comprises an operating surface for providing a flexible, flat workpiece. Thus, the flat workpiece is randomly provided on the operating surface. In this regard, the camera is arranged and configured to generate a camera image of the flat workpiece provided on the operating surface. Thus, relatively constant boundary conditions are established for generating the camera image and for removing the flat workpiece by the first gripper. As a result, the positioning device operates reliably.

[0023] The positioning device may also include a drop distance for the flat workpiece. The flat workpiece falls along this drop distance before becoming usable on the operating surface. In particular, the flat workpiece falls directly onto the operating surface. As the flat workpiece falls along the drop distance, it spreads at least somewhat, so that the area covered by the flat workpiece on the operating surface is increased compared to a variation without the drop distance. This allows the flat workpiece to be relatively easily removed by the first gripper.

[0024] In one variant, the drop distance is divided into at least several sections by a ventilation unit with several outlet openings. This allows the flat workpiece moving along the drop distance to move against the airflow generated by the ventilation unit. Compared to a variant without a ventilation unit, the flat workpiece is at least somewhat spread out, i.e., the area occupied by the flat workpiece on the operating surface is increased. This allows the flat workpiece to be particularly easily lifted by the first gripper.

[0025] In the first alternative, multiple outlet openings are provided in the ventilation surface. The ventilation surface extends substantially horizontally and coincides with the operating surface. In other words, the operating surface has outlet openings therein that generate an air flow directed substantially vertically upward. The flat workpiece falls onto the operating surface against this air flow, so that it can be reliably removed by the first gripper. Furthermore, such a positioning device has a compact design.

[0026] In a second alternative, multiple outlet openings are provided in a ventilation surface inclined at an angle of less than 90 degrees relative to the horizontal. The operating surface is adjacent to the lower edge of the ventilation surface. That is, the flat workpiece falls above the ventilation surface and then slides from the ventilation surface onto the operating surface. The flat workpiece is thus available on the operating surface, where it can be reliably lifted by the first gripper.

[0027] Alternatively or additionally, the serving area comprises a serving container in which one or more flexible, flat workpieces can be served.

[0028] In a first variant, the dispensing area includes the dispensing container but does not include the operating surface. In this case, the first gripper removes the flat workpiece directly from the dispensing container. If multiple flat workpieces are present in the dispensing container, singulation also occurs during the process, i.e., only one flat workpiece is grasped from the dispensing container. The camera is arranged and configured to generate a camera image of the flat workpiece in the dispensing container. The positioning device according to this variant is structurally simple and particularly compact.

[0029] In a second variant, the supply area includes both the supply container and the operating surface. In this variant, the flat workpiece to be positioned is first transferred from the supply container to the operating surface. In this connection, multiple flexible flat workpieces may be present in the supply container, and therefore individualization must also be performed. In this case, the camera is configured and arranged to generate a camera image of the flat workpiece present on the operating surface. Similarly, the first gripper is configured to grasp the flat workpiece from the operating surface. This variant achieves the same effects and advantages as those already described with respect to the operating surface.

[0030] According to one embodiment, the positioning device includes a presentation manipulator with a presentation gripper, which is configured to transfer the flat workpiece provided by the presentation container onto the operating surface. In particular, the presentation manipulator and presentation gripper operate fully automatically, allowing the flat workpiece to be transferred directly onto the operating surface. Alternatively, it can be transferred to the operating surface via the already-described drop distance or via a conveyor, e.g., a conveyor belt. In all variants, the flat workpiece is presented so that it can be quickly and reliably grasped by the first gripper.

[0031] According to one variant, the first gripper comprises two gripper jaw pairs, with a free space being provided between the two gripper jaw pairs.

[0032] A gripper jaw pair here refers to a total of two gripper jaws that interact with each other to grip a flat workpiece, i.e., can clamp the flat workpiece between them. The gripper jaws thus forming a gripper jaw pair are variable in terms of their distance so that a gripping operation can be performed. The first gripper comprises two such gripper jaw pairs.

[0033] Preferably, each upper gripper jaw and each lower gripper jaw of two gripper jaw pairs are rigidly connected to each other, so that only a single drive is provided for driving the two gripper jaw pairs.

[0034] The first gripper thus has a simple structural design and can be manufactured in a cost-effective manner, while at the same time flat workpieces can thus be gripped reliably.

[0035] Furthermore, the first gripper may include a sensor for monitoring free space to detect whether a flat workpiece has been gripped by the first gripper, the sensor being preferably an optical sensor.

[0036] The free space between the two gripper jaw pairs is formed by each or each gripper jaw pair, giving the first gripper the shape of a fork with two prongs.

[0037] In this context, the free space may be dimensioned to be able to accommodate at least a portion of the second gripper and at least a portion of the third gripper when the second gripper and the third gripper are positioned at a minimum distance and / or in their initial positions, where the initial positions of the second gripper and the third gripper correspond to the positions at which the two grippers take over the flat workpiece from the first gripper.

[0038] In particular, the second and third grippers are positioned as close as possible to one another, ie at a minimum distance, by the linear drive unit or by the second and third manipulators.

[0039] In other words, the fork-shaped first gripper is designed so that the second and third grippers can move between the two prongs of the fork and take over the flat workpiece, resulting in a particularly reliable and error-free transfer of the flat workpiece from the first gripper to the second and third grippers.

[0040] According to one embodiment, a control unit is provided that includes a first machine learning module configured to identify a grippable edge of a flexible, flat workpiece based on a camera image of the flat workpiece generated by the camera. Alternatively or additionally, the control unit includes a second machine learning module configured to determine a gripping point for the first gripper based on the camera image of the flexible, flat workpiece generated by the camera. Alternatively or additionally, the control unit includes a third machine learning module configured to identify a type of the flexible, flat workpiece based on the camera image of the flexible, flat workpiece generated by the camera.

[0041] Preferably, each of the machine learning modules comprises a trained artificial neural network, such that the grippable edge of the flat workpiece and / or the gripping point located on the grippable edge for the first gripper and / or the type of flexible flat workpiece can be identified in a simple and reliable manner.

[0042] In particular, the type of flexible flat workpiece is identified from a number of predefined types. If the type of flat workpiece is known, the identification of the graspable edge, the determination of the gripping point, and additional processing steps can be tailored to this specific type. Thus, the flat workpiece can be positioned quickly and reliably.

[0043] For large scale laundry applications, the predefined types may include small towels, large towels, pillows, napkins, bed linens, incontinence pads, and tablecloths.

[0044] In one alternative, the identification of the type of flat workpiece may be utilized solely to distinguish processable flat workpieces from non-processable flat workpieces, and when a non-processable type of flat workpiece is detected, the associated flat workpiece is removed from the operating surface or processing is otherwise stopped or canceled.

[0045] Alternatively or additionally, the control unit includes a fourth machine learning module configured to identify a material of the flexible flat workpiece based on a camera image of the flexible flat workpiece generated by the camera.

[0046] Preferably, the fourth machine learning module also includes a trained artificial neural network, so that the material of the flexible and flat workpiece can be identified in a simple and reliable manner.

[0047] Here, the material of the flexible flat workpiece is identified in particular from a plurality of predefined materials or material groups. In one alternative, the identification of the material of the flat workpiece can be used only to distinguish flat workpieces made from a material to be processed, for example, terry cloth, from flat workpieces that are not to be processed, for example, made from a material other than terry cloth. If a flat workpiece made from a material that is not to be processed is detected, the flat workpiece is removed from the positioning device or its processing is otherwise interrupted.

[0048] Additionally, the object is achieved by a method for positioning a flexible, flat workpiece, which is carried out in particular by a positioning device according to the invention, said method comprising the following steps: a) providing a flat workpiece on a providing area, the flat workpiece being in a random state; b) gripping an edge of the flat workpiece with a first gripper; c) transferring the flat workpiece from the first gripper to the second gripper and the third gripper, whereby the second gripper and the third gripper grip an edge of the flat workpiece; d) placing the flat workpiece in a flat state by the second gripper and the third gripper;

[0049] Here, the random state is specifically a randomly folded state. Furthermore, it should be understood that the edge gripped by the first gripper must be a grippable edge; otherwise, the gripper will not be able to grip it.

[0050] As previously discussed in connection with the positioning device of the present invention, the flat workpiece may be provided on an operating surface or in a provision container.

[0051] Proceeding from this, the flat workpiece can be placed flat using a single re-gripping action by the second and third grippers. This means that the method involves only a few steps related to handling the flat workpiece and is therefore simple. It can also proceed at high speed. Preferably, the method proceeds in an automated manner.

[0052] According to one variant, a camera image showing a flat workpiece located in the provision area is generated by a camera. The camera image is transmitted to a first machine learning module of the control unit, which identifies the position of the edge of the flat workpiece based on the camera image. The identified edge corresponds to the edge at which the first gripper grips the flat workpiece. To determine the position of the edge, the first machine learning module extracts, in particular, characteristic image features of the camera image. For this purpose, the first machine learning module may include a trained artificial neural network. The network receives the camera image or a partial image of the camera image to extract the characteristic image features. This allows the position of the edge of the flat workpiece to be identified relatively quickly and reliably.

[0053] To identify the edge position, the camera image can be divided into multiple sub-images. This is particularly performed by the control unit. For each sub-image, specific image features are extracted by a first machine learning module of the control unit, and based on the specific image features, a probability is established for each sub-image that it represents an edge of a flat workpiece. In particular, a probability is established for each sub-image that it belongs to one of multiple predefined categories. Therefore, the first machine learning module can also be called an image processing unit. Extraction of the specific image features is performed quickly and reliably using such a machine learning module. In this way, graspable edges can be identified quickly and reliably.

[0054] In textile washing applications, the categories "no edge", "graspable edge" and "non-graspable edge" can be used in this context. This means that for each sub-image, a probability is established that it belongs to said category. If a sub-image with a relatively highest probability is found in the "graspable edge" category, a graspable edge is considered to have been identified.

[0055] The artificial neural network used may contain, for example, 10 to 180 layers, with 34, 56 or 152 layers being particularly advantageous here.

[0056] The camera image or at least the partial image of the camera image can be transmitted to a second machine learning module of the control unit, which then uses the camera image or the partial image of the camera image to identify a gripping point of the first gripper. Preferably, the gripping point of the first gripper is determined on a portion of a flat workpiece, the imaging of which, in the camera image or the associated partial image, has established by the first machine learning module a relatively highest probability that the camera image or the partial image shows an edge.

[0057] To determine the gripping point, characteristic image features of the camera image or partial image are again extracted, and based on the characteristic image features, gripping coordinates and gripping orientations are calculated for the first gripper. To this end, the second machine learning module may include a trained artificial neural network. The gripping point may first be calculated in image coordinates and then converted to machine coordinates associated with the first gripper. In this way, the gripping point for the first gripper can be quickly and reliably determined.

[0058] The artificial neural network used in the second machine learning module similarly has, for example, 10 to 180 layers.

[0059] In one embodiment, the second and third grippers substantially simultaneously grip a portion of the edge located in the free space between the two gripper jaw pairs of the first gripper to transfer the flat workpiece from the first gripper to the second and third grippers, so that the portion of the edge located in the free space of the first gripper can be gripped particularly reliably.

[0060] After the flat workpiece is transferred to the second and third grippers, the flat workpiece can be held by the second gripper, and the third gripper can move away from the second gripper until the third gripper reaches a first corner of the flat workpiece. Alternatively, after the flat workpiece is transferred to the second and third grippers, the flat workpiece can be held by the third gripper, and the second gripper can move away from the third gripper until the second gripper reaches a second corner of the flat workpiece. According to a further alternative, after the flat workpiece is transferred to the second and third grippers, the second and third grippers can simultaneously move away from each other until the third gripper reaches a first corner of the flat workpiece and the second gripper reaches a second corner of the flat workpiece. In this way, at least one of the second and third grippers performs a relative movement with respect to the flat workpiece. It is also possible for both the second and third grippers to move with respect to the flat workpiece. In all variants, the second and third grippers move away from each other along the direction of movement of the linear drive unit. In a simplified concept, one or both of the second and third grippers move along the edge of the flat workpiece to the corner. Of course, it must be taken into account here that the actual movement of the second and / or third gripper is specified by the linear drive unit and the edge is deformed accordingly. In this way, the flat workpiece can be easily and reliably transferred in a flat, unfolded state.

[0061] According to one variant, to move the second gripper away from the third gripper and / or to move the third gripper away from the second gripper, the gripping force of the second gripper and / or the third gripper is reduced compared to a predetermined initial gripping state. Alternatively or additionally, to move the second gripper away from the third gripper and / or to move the third gripper away from the second gripper, the second gripper and / or the third gripper opens by a predetermined amount. The flat workpiece is always firmly gripped by the second gripper and the third gripper, so that it is reliably held by each gripper.

[0062] In other words, the flat workpiece is prevented from moving away from the second gripper and from the third gripper (e.g., by sliding out of them). At the same time, however, the flat workpiece is firmly held by the second gripper and / or the third gripper, and a driving movement introduced into one or both grippers by the linear drive unit causes relative movement between the second gripper and / or the third gripper and the gripped flat workpiece. In this way, the flat workpiece can slide through the respective grippers without falling.

[0063] When a flat workpiece is provided on the operating surface, before generating the camera image, the contact area of ​​the flat workpiece on the operating surface can be enlarged starting from a random state, in particular by moving the flat workpiece relative to the airflow, as already explained in connection with the positioning device according to the invention, so that it becomes easier to grip the flat workpiece by the first gripper.

[0064] According to an alternative, the type of the flat workpiece can be identified by a third machine learning module of the control unit before identifying the grippable edge, in particular the type of the flat workpiece can be identified from a plurality of predefined types, resulting in the effects and advantages already described in relation to the positioning device.

[0065] In this context, the third machine learning module may include a trained artificial neural network that receives the camera image or a sub-image of the camera image to extract characteristic image features.

[0066] All of the above artificial neural networks are trained using, for example, freely available datasets in which images or subimages are annotated according to the task of the artificial neural network. The images or subimages used for training purposes are therefore derived from free sources. They are then assigned to predefined categories to solve the respective tasks of the artificial neural network. In particular, the datasets of the ImageNet project from Stanford University and Princeton University (available at www.image-net.org) can be used for this purpose. Alternatively or additionally, it is possible to train a neural network using, for example, 1,000 to 5,000 images per class, i.e., per type or category of object to be recognized. If necessary, an artificial neural network trained using a freely available dataset can subsequently be trained using a dedicated dataset.

[0067] In this context, all of the artificial neural networks may be convolutional neural networks, which are particularly suited to the above tasks. Here, the architecture of the artificial neural network is based on the architecture described in the paper (K. He, X. Zhang, S. Ren and J. Sun, "Deep Residual Learning for Image Recognition", 2016 IEEE Conference on Computer Vision and Pattern Recognition), where the last layer of the artificial neural network is always adapted to each specific task.

[0068] Apart from that, the effects and advantages already discussed with respect to the positioning device according to the invention also apply to the method according to the invention, and vice versa. [Brief explanation of the drawings]

[0069] The present invention will now be described with reference to various exemplary embodiments thereof as illustrated in the accompanying drawings.

[0070] [Figure 1] 1 shows a positioning device according to the present invention according to a first embodiment, with which the method according to the present invention for positioning a flexible flat workpiece can be carried out, and also shows an additional processing machine and a flat workpiece to be positioned. [Figure 2] 2 shows a first gripper of the positioning device from FIG. 1 in an exploded perspective view; [Figure 3] 3 shows the first gripper from FIG. 2 in a top view. [Figure 4] 3 shows the first gripper from FIG. 2 in a side view. [Figure 5] The first gripper from Figures 2 to 4 is shown in a side view corresponding to Figure 4, with the first gripper open. [Figure 6] 2 shows in an isolated representation the handling assembly of the positioning device from FIG. 1 with second and third grippers, whereby a flat workpiece is gripped by the second and third grippers; [Figure 7] 7 shows the handling assembly from FIG. 6 with the second and third grippers in different positions, and a flat workpiece being gripped by the second and third grippers. [Figure 8] 8 shows the handling assembly and flat workpiece from FIG. 7 in a perspective view. [Figure 9] 9 shows an alternative to the handling assembly from FIGS. 6-8, where the flat portion is again gripped. [Figure 10]1 shows a positioning device according to the present invention according to a second embodiment, with which the method according to the present invention for positioning a flexible flat workpiece can be carried out, and also shows an additional processing machine and a flat workpiece to be positioned. [Figure 11] 1 shows a positioning device according to the present invention according to a third embodiment, with which the method according to the present invention for positioning a flexible flat workpiece can be carried out, and shows an additional processing machine and two flat workpieces to be positioned. [Figure 12] 1 shows a schematic diagram for explaining the present invention. [Figure 13] 1 shows a further schematic diagram for explaining the invention. DETAILED DESCRIPTION OF THE INVENTION

[0071] FIG. 1 shows a positioning device 10 for positioning a flexible, flat workpiece.

[0072] In the illustrated embodiment, the positioning device 10 is configured to feed the flexible, flat workpieces 12, which are provided in a random state, in a flattened state into an additional processing machine 14. More specifically, the flexible, flat workpieces 12 are placed in a flattened state on a belt conveyor 16, which includes a plurality of conveyor belts.

[0073] The flexible flat workpiece 12 is, for example, a towel.

[0074] The positioning device 10 comprises a presentation area 18 which, in the first embodiment according to FIG. 1, comprises an operating surface 20 for presenting a flexible, flat workpiece 12 .

[0075] Further, the positioning device 10 includes a camera 22, which is positioned within the positioning device 10 and configured to generate a camera image B of the presentation area 18, more specifically, the flat workpiece 12 presented on the operation surface 20.

[0076] In this case, the camera 22 is fixed in the region of a frame 24 of the positioning device 10, which is installed vertically above the operating surface 20. The operating surface 20 is located entirely within the detection field of the camera 22.

[0077] The positioning device 10 further comprises a first manipulator 26, which in the illustrated embodiment is in the form of an industrial robot.

[0078] The first manipulator 26 carries a first gripper 28 .

[0079] It is configured to grip a portion of a flexible, flat workpiece 12 located in a presentation area 18 .

[0080] The first gripper 28 is shown in detail in FIGS.

[0081] It includes a first gripper jaw pair 30 which includes a lower gripper jaw 32 and an upper gripper jaw 34 .

[0082] Additionally, the first gripper 28 is provided with a second gripper jaw pair 36 .

[0083] It also includes a lower gripper jaw 38 and an upper gripper jaw 40 .

[0084] It should be understood that due to the gripper 28 being fixed to the first manipulator 26, the gripper 28 can assume almost any desired orientation in space. Thus, the designations "upper" and "lower" merely serve to simplify the designation of the gripper jaws 32, 34, 38, 40 and essentially refer to the orientation of the first gripper 28 as shown in FIG. 2.

[0085] The lower gripper jaws 32, 38 are rigidly connected to one another.

[0086] Similarly, the upper gripper jaws 34, 40 are rigidly connected to one another.

[0087] The first gripper 28 further includes an actuator 42 configured to selectively lift the upper gripper jaws 34, 40 from the associated lower gripper jaws 32, 38, respectively, or to move the upper gripper jaws 34, 40 closer to the lower gripper jaw 32 (see, in particular, Figures 4 and 5 for comparison).

[0088] Furthermore, a free space 44 is provided between the gripper jaw pairs 30, 36 (see especially FIG. 3). Thus, the gripper jaw pairs 30, 36 have a distance d from each other.

[0089] Additionally, to facilitate picking up and holding of flat workpieces 12, the individual lower gripper jaws 32, 38 are provided with curved holding surfaces 46, 48 at their tip regions, respectively.

[0090] The upper gripper jaws 34, 40 each include a holding tip 50, 52 for pressing the flat workpiece 12 against the lower gripper jaws 32, 38. In particular, the flat workpiece 12 is pressed against the holding surfaces 46, 48.

[0091] The positioning apparatus 10 further includes a handling assembly 54 .

[0092] The handling assembly 54 is shown in detail in FIGS.

[0093] It comprises a linear drive unit 56 , a second gripper 58 and a third gripper 60 .

[0094] The second gripper 58 and the third gripper 60 are drivingly coupled to the linear drive unit 56 so that the second gripper 58 and the third gripper 60 are each movable along the direction of movement L of the linear drive unit 56 .

[0095] The drive connection of the grippers 58, 60 to the linear drive unit 56 is here designed in such a way that the second gripper 58 and the third gripper 60 can only move dependently on each other, in other words, when the second gripper 58 moves, the third gripper 60 moves and vice versa.

[0096] Additionally, second gripper 58 and third gripper 60 are each configured to take over a portion of flexible flat workpiece 12 from first gripper 28 .

[0097] To this end, the second gripper 58 includes a gripper jaw pair comprising a first gripper jaw 62 and a second gripper jaw 64 .

[0098] The first gripper jaw 62 and the second gripper jaw 64 are movable relative to one another by an actuator 65 to selectively clamp and release the flat workpiece 12 therebetween.

[0099] The third gripper 60 similarly includes a gripper jaw pair having a first gripper jaw 66 and a second gripper jaw 68 .

[0100] Here, first gripper jaw 66 and second gripper jaw 68 are movable relative to one another by actuator 69 to selectively clamp and release flat workpiece 12 therebetween.

[0101] An actuator 70 is provided for moving the second gripper 58 and the third gripper 60 along the movement direction L.

[0102] Additionally, the handling assembly 54 is rotatably mounted on the frame 24 .

[0103] Here, the axis of rotation is oriented parallel to the longitudinal extent of the handling assembly 54, i.e., the axis of rotation is parallel to the direction of movement L corresponding to the longitudinal extent.

[0104] To this end, the handling assembly is mounted to the frame 24 by means of a first rotation bearing 72 and a second rotation bearing 74 .

[0105] Additionally, a rotational drive 76 is provided by which the handling assembly 54 is rotatable relative to the frame 24 .

[0106] With respect to their distance and their rotational position resulting from the rotational position of the handling assembly 54, the second gripper 58 and the third gripper 60 can assume an initial position in which the grippers 58, 60 are positioned at a relatively small distance, in particular a minimum distance, from each other (see in particular Figure 6).

[0107] Starting there, the second gripper 58 and the third gripper 60 are movable away from each other and can be transported to positions away from each other (see Figures 7 and 8).

[0108] Here, the initial positions of the second gripper 58 and the third gripper 60 are coordinated with the first gripper 28, and in this initial position the second gripper 58 and the third gripper 60 can move at least several sections into the free space 44 of the first gripper 28 (see also Figure 11).

[0109] In other words, the free space 44 is dimensioned so as to accommodate at least a portion of the second gripper 58 and the third gripper 60 when the second gripper 58 and the third gripper 60 are in their initial positions.

[0110] As an alternative to the handling assembly 54, the positioning device 10 may include a second manipulator 54a and a third manipulator 54b, the second manipulator 54a carrying a second gripper 58 and the third manipulator 54b carrying a third gripper 60 (see FIG. 9).

[0111] In this case, the manipulators 54 a , 54 b are in the form of two independent industrial robots that cooperate with each other to manipulate the flat workpiece 12 .

[0112] In contrast to the handling assembly 54, the grippers 58, 60 are not rotationally mounted, since they can be positioned and oriented more or less freely in space by the manipulators 54a, 54b.

[0113] Alternatively, reference may be made to the discussion regarding handling assembly 54, which applies equally to the second manipulator 54a and third manipulator 54b alternatives.

[0114] In particular, grippers 58, 60 are identical in construction to the alternatives that include handling assembly 54.

[0115] A control unit 78 is also provided for operating the positioning device 10 (see Figure 1).

[0116] The control unit includes a first machine learning module 80 configured to identify a graspable edge K of the flexible flat workpiece 12 based on a camera image B generated by the camera 22 of the flat workpiece 12.

[0117] To this end, the first machine learning module is equipped with a trained artificial neural network 82 .

[0118] Further, a second machine learning module 84 is provided, which is configured to determine a gripping point of the first gripper 28 based on the camera image B of the flexible, flat workpiece 12 generated by the camera 22. The gripping point includes a gripper position and a gripper orientation of the first gripper 28, and is located in particular in the region of the graspable edge K.

[0119] The second machine learning module 84 is also equipped with a trained artificial neural network 86 .

[0120] Further, a third machine learning module 88 is provided, which is configured to identify the type of the flexible and flat workpiece 12 based on the camera image B of the flexible and flat workpiece 12 generated by the camera 22.

[0121] The third machine learning module 88 similarly includes a trained artificial neural network 90 .

[0122] It will be understood that the control unit 78 should be at least indirectly connected to each actuator and each sensor of the positioning device 10. In Figure 1, for the sake of greater clarity, only some of these connections are depicted in an exemplary manner with dashed lines.

[0123] The function of the control unit 78 and the positioning apparatus 10 as a whole, along with a method for positioning a flexible, flat workpiece 12, are discussed below.

[0124] The objective of this method is to transfer the flexible, flat workpiece 12, starting from a random, particularly irregularly folded state, to a flat, unfolded state for feeding it into an additional processing machine 14.

[0125] In this process, flat workpieces 12 are first presented in a random orientation on an operating surface 20 .

[0126] In this state, a camera image B of the flat workpiece 12 is generated by the camera 22 and transmitted to the control unit 78 .

[0127] Camera image B is then divided into sub-images by control unit 78 .

[0128] The sub-images are sent to a first machine learning module 80, and in particular an associated artificial neural network 82, which extracts distinctive image features for each sub-image to establish the probability that it represents a graspable edge K of the flat workpiece.

[0129] More precisely, for each sub-image, a probability is established that it belongs to one of the categories "no edge", "graspable edge" and "non-graspable edge". If a sub-image with the highest relative probability of the category "graspable edge" is found, then a graspable edge K is considered to be established.

[0130] In this manner, the location of the graspable edge K of the flat workpiece 12 can be identified by the first machine learning module 80.

[0131] At least a partial image of the camera image B showing the edge K is additionally sent to a second machine learning module 84 .

[0132] By extracting distinctive image features of at least this sub-image using an artificial neural network 86, the second machine learning module identifies a gripping point for the first gripper 28, which is located on the edge K identified by the first machine learning module 80.

[0133] Optionally, camera image B is also sent to a third machine learning module 88. This machine learning module 88 includes an artificial neural network 90 that can identify the type of flat workpiece by extracting distinctive image features. In this way, for example, flat workpieces 12 that do not conform to a particular type can be identified and rejected from the presentation area 18.

[0134] In this example, flat workpieces 12 other than towels can be detected and excluded from processing.

[0135] The identified grippable edge K of the flat workpiece 12 is then gripped by the first gripper 28 .

[0136] For this purpose, the respective lower gripper jaws 32, 38 are provided with arcuate holding surfaces 46, 48 and are guided below the edge K to be gripped by the pivoting movement of the first gripper 28. In the position resulting from this movement, the flat workpiece 12 is gripped by closing the grippers 28, i.e. by the respective upper gripper jaws 34, 40 approaching the lower gripper jaws 32, 38.

[0137] The flat workpiece 12, more precisely the part of its grippable edge K located between the two gripper jaw pairs 30, 36, is then transferred to the second gripper 58 and the third gripper 60, which take up their initial positions for this purpose (see Figure 6).

[0138] If, instead of the handling assembly 54, the positioning device 10 is provided with a second manipulator 54a and a third manipulator 54b, these carry a second gripper 58 and a third gripper 60, respectively, which are transferred to positions corresponding to those shown in FIG. 6 using the manipulators 54a, 54b.

[0139] Using the first manipulator 26, the first gripper 28, along with the gripped flat workpiece 12, is positioned relative to the second gripper 58 and the third gripper 60 so that the second gripper 58 and the third gripper 60 move substantially simultaneously into the free space 44 between the gripper jaw pairs 30, 36 (see FIG. 12).

[0140] The first gripper 28 is then moved by the first manipulator 26 to a position away from the handling assembly 54 .

[0141] Here, the flat workpiece 12 needs to be transferred to a flat transfer position.

[0142] For this purpose, the gripping force of both the second gripper 58 and the third gripper 60 is reduced compared to the initial gripping state, which corresponds to the gripping state in which these two grippers 58, 60 take over the flat workpiece 12 from the first gripper 28.

[0143] Now, the reduced gripping force is large enough to continue to hold the flat workpiece 12 by the second gripper 58 and the third gripper 60. This means that the flat workpiece 12 will not slip off these grippers 58, 60.

[0144] At the same time, however, the gripping force is small enough so that relative movement between the flat workpiece 12 and the grippers 58, 60 along the direction L is possible.

[0145] In this regard, both the second gripper 58 and the third gripper 60 move outward until both grippers 58, 60 reach their individually assigned corners E of the flat workpiece 12 (see FIG. 13, where the starting positions of the grippers 58, 60 are indicated by dashed lines).

[0146] To detect the corner E, both grippers 58, 60 are equipped with appropriate sensors, in particular optical sensors 92, 94.

[0147] In the positioning device 10 including the handling assembly 54, with the second gripper 58 and the third gripper 60 in this relative position with respect to the flat workpiece 12, the handling assembly 54 is rotated by the rotary drive 76 toward the belt conveyor 16. The flat workpiece 12 is then placed flat thereon by opening the grippers 58, 60, thereby releasing the flat workpiece 12.

[0148] In a variation of the positioning apparatus 10 that includes a second manipulator 54a and a third manipulator 54b, corresponding movements of the grippers 58, 60 are achieved by the manipulators 54a, 54b to deposit the flat workpiece 12 in a planar orientation.

[0149] The above-described traversal movement of the grippers 58, 60 can be made easier if the gripped edge K of the flat workpiece 12 has a hem that includes a thickened portion on the edge of the flat workpiece 12. Such thickened portion prevents slippage from the grippers 58, 60, but allows the grippers 58, 60 to traverse relative to the edge K.

[0150] In one variation of this method, the grippers 58, 60 do not move simultaneously relative to the flat workpiece, but alternately, i.e., the flat workpiece 12 is first gripped by one of the grippers 58, 60 with an unreduced gripping force, and then the respective other gripper 58, 60 is traversed by the linear drive unit 56 until the associated corner E is reached.

[0151] Next, the flat workpiece 12 is held by the grippers 58, 60 that have reached the corner E, and the gripping force of the grippers is no longer reduced. Therefore, the other gripper 58, 60 moves laterally until it reaches the other corner E.

[0152] FIG. 10 shows a positioning device 10 according to the second embodiment.

[0153] Only the differences from the first embodiment shown in FIGS. 1 to 9 will be described below.

[0154] Furthermore, identical or corresponding elements of the positioning device 10 are given the same reference numerals.

[0155] In the second embodiment, the dispensing area 18 comprises a dispensing container 96 instead of the operating surface 20. One or more flexible flat workpieces 12 are provided in this container, with only a single flat workpiece 12 shown in FIG. 10 by way of example.

[0156] In this case, the camera 22 is again configured and positioned to generate a camera image of the flat workpiece 12 within the dispense container 96 .

[0157] The method for positioning the flexible, flat workpiece 12 proceeds similarly to the first embodiment. This applies to both the variant including the handling assembly 54 and the variant including the second manipulator 54a and the third manipulator 54b. The flat workpiece 12 is grasped from the supply container 96 rather than from the operating surface 20.

[0158] 11 shows a third embodiment of the positioning device 10. Here, only the differences from the first and second embodiments will be described.

[0159] Identical or corresponding elements of the positioning device 10 are given the same reference numerals.

[0160] Here, the dispensing area 18 of the positioning device 10 includes both the operation surface 20 and the dispensing container 96. In this regard, the third embodiment is a combination of the first and second embodiments.

[0161] Furthermore, a delivery manipulator 98 is provided, which is shown only diagrammatically in FIG. 11 and which is in the form of an industrial robot.

[0162] A presentation gripper 100 is attached to the presentation manipulator 98 .

[0163] Here, the present manipulator 98 and the present gripper 100 transfer the flexible, flat workpiece 12 from the present container 96 onto the operating surface 20. To this end, the present manipulator 98 and the present gripper 100 are connected to the control unit 78.

[0164] Proceeding from a state in which the flat workpiece 12 is on the operating surface 20, the method of positioning the flexible flat workpiece 12 proceeds in the same manner as in the first embodiment. Again, this applies to both variants of the first embodiment.

Claims

1. A positioning device (10) for positioning a flexible, flat workpiece (12), comprising: a presentation area (18) for presenting a flexible, flat workpiece (12) to be positioned; a camera (22) positioned and configured to generate a camera image (B) of a flexible, flat workpiece (12) to be positioned in the presentation area (18); a first manipulator (26) carrying a first gripper (28) configured to grasp at least a portion of the flexible, flat workpiece (12) from the presentation area (18); A second gripper (58); a third gripper (60); the second gripper (58) and the third gripper (60) are each configured to take over at least a portion of the flexible, flat workpiece (12) from the first gripper (28); the second gripper (58) and the third gripper (60) are drivingly connected to the linear drive unit (56), such that the second gripper (58) and the third gripper (60), respectively, are movable along the linear drive unit (56); or the second gripper (58) is carried by the second manipulator (54a) and the third gripper (60) is carried by the third manipulator (54b); the first gripper (28) comprises two gripper jaw pairs (30, 36) with a free space (44) between the two gripper jaw pairs (30, 36); The positioning device (10) is configured such that the free space (44) is dimensioned to be able to accommodate at least a portion of the second gripper (58) and at least a portion of the third gripper (60) when the second gripper (58) and the third gripper (60) are positioned at a minimum distance and / or at their initial positions.

2. A positioning device (10) for positioning a flexible, flat workpiece (12), comprising: a presentation area (18) for presenting a flexible, flat workpiece (12) to be positioned; a camera (22) positioned and configured to generate a camera image (B) of a flexible, flat workpiece (12) to be positioned in the presentation area (18); a first manipulator (26) carrying a first gripper (28) configured to grasp at least a portion of the flexible, flat workpiece (12) from the presentation area (18); A second gripper (58); a third gripper (60); the second gripper (58) and the third gripper (60) are each configured to take over at least a portion of the flexible, flat workpiece (12) from the first gripper (28); the second gripper (58) and the third gripper (60) are drivingly connected to the linear drive unit (56), such that the second gripper (58) and the third gripper (60) are each movable along the linear drive unit (56); the first gripper (28) comprises two gripper jaw pairs (30, 36) with a free space (44) between the two gripper jaw pairs (30, 36); the free space (44) is dimensioned to be able to receive at least a portion of the second gripper (58) and at least a portion of the third gripper (60) when the second gripper (58) and the third gripper (60) are positioned at a minimum distance and / or at their initial positions; The linear drive unit (56), together with the second gripper (58) and the third gripper (60), is mounted within the positioning device (10) and is rotatable about an axis extending parallel to its longitudinal extent (L).

3. 3. The positioning device (10) according to claim 1 or 2, characterized in that the presentation area (18) comprises an operating surface (20) for presenting a flexible and flat workpiece (12).

4. Positioning device (10) according to any one of claims 1 to 3, characterized in that the presentation area (18) comprises a presentation container (96) in which one or more flexible flat workpieces (12) can be presented.

5. 5. The positioning device (10) of claim 4, wherein the providing manipulator (98) has a providing gripper (100), and the providing manipulator (98) is configured to transfer a flat workpiece (12) provided by the providing container (96) onto the operating surface (20).

6. a first machine learning module (80) configured to identify a graspable edge (K) of the flexible, flat workpiece (12) based on a camera image (B) of the flat workpiece (12) generated by the camera (22); and / or a second machine learning module (84) configured to determine a gripping point for the first gripper (28) based on a camera image (B) of the flexible, flat workpiece (12) generated by the camera (22); and / or 6. The positioning device (10) according to claim 1, further comprising a control unit (78) including a third machine learning module (88) configured to identify the type of the flexible, flat workpiece (12) based on a camera image (B) of the flexible, flat workpiece (12) generated by the camera (22).

7. A method for positioning a flexible, flat workpiece (12) using a positioning device (10) according to any one of claims 1 to 6, comprising: a) providing a flat workpiece (12) in a providing area (18), the flat workpiece (12) being in a random state; b) gripping an edge (K) of the flat workpiece (12) by a first gripper (28); c) transferring the flat workpiece (12) from the first gripper (28) to the second gripper (58) and the third gripper (60) so that the second gripper (58) and the third gripper (60) grip the edge (K) of the flat workpiece (12); d) placing the flat workpiece (12) in a flat position by a second gripper (58) and a third gripper (60).

8. a camera image (B) showing a flat workpiece (12) located in a presentation area (18) is generated by a camera (22); The camera image (B) is transmitted to a first machine learning module (80) of the control unit (78); The method of claim 7, wherein the first machine learning module (80) identifies the location of an edge (K) of the flat workpiece (12) based on the camera image (B).

9. 9. The method of claim 8, wherein, to identify the location of the edge (K), the camera image (B) is divided into a plurality of sub-images by the control unit (78), characteristic image features are extracted for each sub-image by a first machine learning module (80) of the control unit (78), and based on the characteristic image features, a probability is established for each sub-image that it represents an edge (K) of the flat workpiece (12), and a probability is established for each sub-image that it belongs to one of a plurality of predefined categories.

10. The camera image (B) or at least a partial image of the camera image (B) is transmitted to a second machine learning module (84) of the control unit (78); 10. The method of claim 8 or 9, wherein the second machine learning module (84) identifies a gripping point for the first gripper (28) based on the camera image (B) or a partial image of the camera image (B).

11. 11. The method according to claim 7, wherein, for transferring the flat workpiece (12) from the first gripper (28) to the second gripper (58) and the third gripper (60), the second gripper (58) and the third gripper (60) substantially simultaneously grip a part of the edge (K) located in the free space (44) between the two gripper jaw pairs (30, 36) of the first gripper (28).

12. After transferring the flat workpiece (12) to the second gripper (58) and the third gripper (60), the flat workpiece (12) is held using the second gripper (58) and the third gripper (60) moves away from the second gripper (58) until the third gripper (60) reaches the first corner (E) of the flat workpiece (12), or After transferring the flat workpiece (12) to the second gripper (58) and the third gripper (60), the flat workpiece (12) is held using the third gripper (60), and the second gripper (58) moves away from the third gripper (60) until the second gripper (58) reaches a second corner (E) of the flat workpiece (12), or 12. The method according to claim 7, wherein after transferring the flat workpiece (12) to the second gripper (58) and the third gripper (60), the second gripper (58) and the third gripper (60) simultaneously move away from each other until the third gripper (60) reaches a first corner (E) of the flat workpiece (12) and the second gripper (58) reaches a second corner (E) of the flat workpiece (12).

13. In order to move the second gripper (58) away from the third gripper (60) and / or to move the third gripper (60) away from the second gripper (58), the gripping force of the second gripper (58) and / or the third gripper (60) is reduced compared to a predetermined initial gripping state, or 13. The method according to claim 12, characterized in that in order to move the second gripper (58) away from the third gripper (60) and / or to move the third gripper (60) away from the second gripper (58), the second gripper (58) and / or the third gripper (60) open by a predetermined amount.

Images