Method and device for determining a gripping position for gripping a workpiece

Description

[0001] The present invention relates to a method for determining a gripping position for gripping a workpiece. Furthermore, the present invention relates to a device for determining a gripping position for gripping a workpiece and a method for gripping a workpiece. BACKGROUND OF THE INVENTION

[0002] Automatically loading a machine tool with workpieces is one way to increase the level of automation in production. However, such an automated loading system often faces the challenge of continuously learning new, customer-specific workpieces.

[0003] In addition to capturing the 3D geometry of the workpiece, possible gripping positions of a gripper / robot must be defined with which the workpiece can be gripped.

[0004] Currently, such loading systems require a) the geometry of the workpiece (e.g., from CAD data) and b) the geometry of the gripper (e.g., from the robot model). The possible gripping positions are then defined, for example, based on the CAD model within software or by directly approaching the workpiece with the robot and saving / teaching the possible gripping positions.

[0005] For example, for the first-mentioned procedure, DE 10 2016 224377 A1 shows a method for gripping an object, in particular a body part, in which CAD model data for the object to be gripped are read into a control unit and theoretical gripping points of the object are determined therefrom by automatic analysis.

[0006] EP 3 020 516 A2 discloses the latter approach.

[0007] In particular, teaching by directly approaching the various gripping positions can be disadvantageous, as the respective gripper / robot must be taught the workpiece through several instructional steps before it can grip the workpiece from the various possible positions. In some cases, such a gripping process must be "played through" step by step, and the corresponding positions and relative positions of the workpiece and the robot must be stored.

[0008] However, since such complex teaching steps can sometimes significantly increase the setup times of the machine tool, such teaching methods lead to a longer downtime of the machine tool, whereby the use of robots can quickly become detrimental to the efficiency of machining despite the higher degree of automation, especially with smaller batch sizes of workpieces. SUMMARY OF THE INVENTION

[0009] An object of the present invention is therefore to provide a method for determining a gripping position for gripping a workpiece, which avoids the above-mentioned disadvantages.

[0010] Furthermore, it is an object of the present invention to provide a device for determining a gripping position for gripping a workpiece and a method for gripping a workpiece.

[0011] To achieve this object, a method for determining a gripping position according to claim 1, a device for determining a gripping position according to claim 6 and a method for gripping a workpiece according to claim 9 are therefore proposed. The dependent claims relate to advantageous embodiments of the respective methods according to the invention and the device according to the invention.

[0012] The method according to the invention for determining a gripping position for gripping a workpiece comprises: providing a plate-shaped device with a projection on a surface that reproduces at least one movement of gripping elements of a gripper, wherein the projection differs in color from the surface of the plate-shaped device and / or comprises depressions in the surface, positioning the workpiece with respect to the plate-shaped device such that an outer contour of the workpiece intersects the projection of the at least one movement of the gripping elements of the gripper, detecting intersection points of the outer contour of the workpiece with the projection of the at least one movement of the gripping elements of the gripper, detecting a workpiece geometry of the workpiece that includes the outer contour of the workpiece,Storing the detected workpiece geometry and the detected intersection points of the outer contour of the workpiece with the projection of the at least one movement of the gripper elements of the gripper, determining the gripping position for gripping the workpiece from the detected intersection points, wherein, based on the detected intersection points of the outer contour of the workpiece with the projection of the at least one movement of the gripper elements of the gripper, a workpiece coordinate system is determined which defines the gripping position for gripping the workpiece, and a relationship between the determined workpiece coordinate system and a gripper coordinate system of the gripper is determined and stored for the workpiece,

[0013] The method according to the invention makes it possible to provide a tool in a simple manner by means of which new or unknown workpieces can be taught to the changing device / gripper without prior knowledge of the workpiece and gripper geometry.

[0014] This is particularly advantageous because any 3D models of the workpiece and gripper are no longer required for the training process. Furthermore, it is a huge advantage that the robot or gripper is not required for training the new / unknown workpiece, thus avoiding any (additional) downtime for these automation systems.

[0015] The method according to the invention allows the workpiece or its geometry to be detected, which is particularly important for the detection of possible gripping positions and for the recognition of the workpiece / the geometry of the workpiece.

[0016] Defining a corresponding workpiece coordinate system allows the gripper to always grasp the workpiece in the position it has been taught. The gripper's own coordinate system (gripper coordinate system) is brought into the previously defined / taught relationship to the workpiece coordinate system before the gripper "grasps."

[0017] Furthermore, the method according to the invention is advantageous because the method according to the invention can be easily applied multiple times for different gripping positions of the workpiece in order to teach the gripper all possible gripping positions on the respective workpiece.

[0018] The recorded data is stored, for example in a storage unit set up for this purpose, whereby this storage unit can also be located centrally and can be accessed by various grippers or changing devices.

[0019] The method according to the invention can be advantageously further developed in that the projection of the at least one movement of the gripping elements of the gripper defines a local coordinate system of the plate-shaped device, wherein the workpiece coordinate system is determined on the basis of the local coordinate system and the detected workpiece geometry.

[0020] In addition, the method according to the invention can be advantageously further developed in that the local coordinate system is defined essentially between the detected intersection points of the outer contour of the workpiece with the projection of the at least one movement of the gripping elements of the gripper.

[0021] The projection of at least one movement of the gripper's gripping elements specifies a local coordinate system from which the workpiece coordinate system can be defined, given knowledge of the workpiece geometry. The local coordinate system of the plate-shaped device can essentially lie between the detected intersection points of the outer contour of the workpiece and the projection of at least one movement of the gripper's gripping elements. However, the local coordinate system can also assume other positions relative to the plate-shaped device and / or the workpiece.

[0022] The method according to the invention can be advantageously further developed in that the detected intersection points are essentially contact points of the gripper at which the workpiece can be gripped by the gripper.

[0023] Advantageously, the detected intersection points essentially represent contact points of the gripper at which the workpiece can be grasped by the gripper. This makes it very easy for a worker / user, for example, to identify where the respective workpiece would be gripped by the gripper and, if necessary, to correct the contact points by, for example, changing the position of the workpiece relative to the plate-shaped device.

[0024] Furthermore, the method according to the invention can be advantageously further developed in that the detected workpiece geometry of the workpiece also comprises the following: a height of the workpiece positioned with respect to the plate-shaped device, and / or a diameter, and / or shape descriptors of the workpiece.

[0025] The various features of the captured workpiece geometry can be used, for example, to define the workpiece coordinate system (e.g., through the captured height of the workpiece relative to the plate-shaped fixture) or to (more reliably) recognize the workpiece. The features listed above are not intended to be exhaustive and can be supplemented by additional features.

[0026] The method according to the invention can also be advantageously further developed in that the projection of the at least one movement of the gripping elements of the gripper has the following shape: the shape of a straight line, the shape of two intersecting straight lines, the shape of two straight lines that intersect perpendicular to each other, the shape of three converging and touching straight lines, the shape of three converging and touching straight lines that are essentially at the same angle to each other, and / or a combination of two or more of the aforementioned shapes.

[0027] The device according to the invention for determining a gripping position for gripping a workpiece for use in a method for determining a gripping position according to, comprises: a detection device configured to determine the gripping position for gripping the workpiece and a plate-shaped device with a projection on a surface that reproduces at least one movement of gripping elements of the gripper, wherein the projection differs in color from the surface of the plate-shaped device and / or comprises depressions in the surface, wherein the detection device is configured to detect and store a workpiece geometry of a workpiece positioned on the plate-shaped device, which comprises an outer contour of the workpiece, to detect and store intersection points of the outer contour of the workpiece with the projection of the at least one movement of the gripping elements of the gripper,and to determine the gripping position for gripping the workpiece from the detected intersection points, and is configured to determine a workpiece coordinate system that defines the gripping position for gripping the workpiece on the basis of the detected intersection points of the outer contour of the workpiece with the projection of the at least one movement of the gripping elements of the gripper, and to determine a relationship between the determined workpiece coordinate system and a gripper coordinate system of the gripper and to store it for the workpiece,

[0028] The device according to the invention made it possible to provide a means in a simple manner by which new or unknown workpieces can be taught without prior knowledge of the workpiece and gripper geometry, in particular since the robot or gripper is not required for teaching the new / unknown workpiece and therefore there is no (additional) downtime of these automation systems.

[0029] The plate-shaped device advantageously makes it possible to position various workpieces on the surface supporting the projection of at least one movement of the gripper elements and to perform the teaching process. Furthermore, a plate-shaped device is advantageous in that it can be used either stationary and / or mobile, and can be moved to the desired location.

[0030] By projecting at least one movement of the gripping elements of the gripper, which differs in color from the surface of the plate-shaped device and / or includes depressions in the surface, 2D / 3D camera systems or appropriately configured laser scanners can reliably capture the projection of the gripping movement and link it accordingly with the captured workpiece geometry.

[0031] The device according to the invention can be advantageously further developed in that the projection of the at least one movement of the gripping elements of the gripper comprises grooves or flutes.

[0032] The device according to the invention can also be advantageously further developed in that the projection of the at least one movement of the gripping elements of the gripper has the following shape: the shape of a straight line, the shape of two intersecting straight lines, the shape of two straight lines that intersect perpendicularly to each other, the shape of three converging and touching straight lines, the shape of three converging and touching straight lines that are substantially at the same angle to each other, and / or a combination of two or more of the aforementioned shapes.

[0033] It should be noted at this point that the forms mentioned are not to be construed as restrictive in any way and can be supplemented by further forms, in particular by parts of the forms already mentioned.

[0034] The inventive method for gripping a workpiece comprises: providing the workpiece to be gripped; detecting an outer contour of the workpiece; recognizing the detected outer contour of the workpiece on the basis of a known outer contour of a known workpiece, wherein the known outer contour of the known workpiece and the associated gripping position for gripping the known workpiece are detected by a method according to the invention for determining a gripping position for gripping a workpiece; and gripping the workpiece by a gripper on the basis of the detected outer contour of the workpiece and the associated gripping position for gripping the workpiece.

[0035] By using the method according to the invention for determining a gripping position for gripping a workpiece, it was possible to provide a simple and universally usable tool for any workpiece and for any changing device / gripper, in order to teach changing devices or grippers, such as a robot gripper, even unknown workpieces. It is particularly advantageous that neither the gripper or the robot itself, nor, for example, the corresponding machine tool, need to be used to carry out the teaching process. All that is required for this is the device according to the invention for determining a gripping position for gripping the workpiece, so that the teaching process can be carried out with the aid of this device and a detection device such as a 3D camera.The data generated in this way, such as workpiece geometry and the corresponding gripping positions, can be saved and retrieved and used for the respective changing device.

[0036] Further aspects and their advantages as well as advantages and more specific embodiments of the aspects and features described above are described in the following, but in no way limiting, descriptions and explanations of the attached figures. BRIEF DESCRIPTION OF THE CHARACTERS

[0037] Fig. 1 schematically shows an embodiment of the device according to the invention with a projection of a movement of the gripping elements of the gripper and a workpiece; Fig. 2 schematically shows an embodiment of the device according to the invention as a transportable device (right side) and as a permanently installed device (left side); Fig. 3 shows a flow chart of an embodiment of the method according to the invention for determining a gripping position for gripping a workpiece; Fig. 4 schematically shows the detection of the workpiece in relation to the device according to the invention by a detection device for determining a workpiece coordinate system; Fig. 5 schematically shows various workpieces as they are positioned by way of example in relation to the device according to the invention and in doing so intersect the projection of the movement of the gripping elements of the gripper; Fig.Fig. 6 schematically shows a plurality of different and partially combined projections of movements of the gripping elements of the gripper that can be provided on the device according to the invention; Fig. 7 schematically shows a changing device for gripping a workpiece from a pallet. DETAILED DESCRIPTION OF THE FIGURES AND PREFERRED EMBODIMENTS OF THE PRESENT INVENTION

[0038] Examples and embodiments of the present invention are described in detail below with reference to the accompanying figures. Identical or similar elements in the figures may be designated by the same reference numerals, although sometimes different reference numerals may be used.

[0039] It should be emphasized, however, that the present invention is in no way limited or restricted to the exemplary embodiments and their embodiment features described below, but further comprises modifications of the exemplary embodiments, in particular those which are encompassed by modifications of the features of the described examples or by combination of one or more of the features of the described examples within the scope of protection of the independent claims.

[0040] Fig. 1 schematically shows an embodiment of the device 100 according to the invention with a projection 110 of a movement of gripping elements 310 of the gripper 300 and a workpiece 200.

[0041] The workpiece 200 is positioned relative to the device 100 such that it intersects the projection 110 of the gripping movement (=movement of gripping elements 310 of the gripper 300). This is possible in particular because the device 100 is designed as a plate 100 or plate-shaped, and the projection 110 of the gripping movement is formed on at least one of the surfaces of the device 100 (hereinafter sometimes also referred to as plate 100) as a color difference from the rest of the plate 100 and / or by depressions (such as grooves and / or ridges, etc.) in the surface of the plate 100.

[0042] In addition, the projection 110 of the gripping movement represents the movement of gripping elements 310 of a gripper 300 (change device), which the gripping elements 310 of the gripper 300 perform when gripping or releasing. Since these are often two-finger grippers or three-finger grippers (or even multi-finger grippers), the projections 110 of the movement of the individual fingers (gripping elements 310) on the surface of the plate 100 are designed as a pair (for example, in the form of a straight line) or as a triple (for example, in the form of three lines converging at a point, possibly at the same angle to each other). Reference should be made at this point to the explanations regarding Fig. 6 referred to.

[0043] Furthermore, a detection device 400 is provided for detecting the geometry of the workpiece 200 and its intersection points with the projection 110 of the gripping movement. The detection device 400 can be designed as a 2D / 3D camera measuring system or as a laser scanner. However, other embodiments of the detection device 400 can also be used.

[0044] The detection device 400 can scan the workpiece 200 as well as the intersection points of the projection 110 of the gripping movement with the workpiece 200 and convert them into data that can be used for a machine control and, if necessary, store them in a corresponding storage unit 2000 (not shown here, see Fig. 2 ) save.

[0045] Fig. 2 shows schematically an embodiment of the device according to the invention (plate 100) as a transportable device (see the right side of the Fig. 2 ) and as a permanently installed device (see the left side of the Fig. 2 ), such as can be used in a factory / production hall.

[0046] It is particularly advantageous if the plate 100 (as shown on the right side of the Fig. 2 shown) is movable or transportable relative to the machine tool 1000 and / or relative to the gripper 300 or the robot 3000, so that it can be used at different robots 3000 or machining stations. This is possible in particular because the plate 100 can be carried by hand by a machine operator / worker, i.e. the plate 100 is not excessively large in its dimensions and weight. Furthermore, the plate 100 can also be mounted on a portable pedestal (as in Fig. 2 shown) which can be positioned accordingly in the movement range of the robot 3000.

[0047] The corresponding detection of the contour of the workpiece 200 and the projection 110 of the gripping movement can then be carried out, for example, by means of the detection device 400 of the robot 3000 or a movable detection device 400 (not shown here).

[0048] However, it can also be very advantageous if the method according to the invention for determining a gripping position by means of the device according to the invention (plate 100) always takes place at one and the same location (such as on the left side of the Fig. 2 shown), and the data obtained therefrom are stored / saved, for example, in a central storage unit 2000, which, for example, can be accessed by various robots within a company / production hall.

[0049] This allows all manufacturing / processing stations to continue processing, while in parallel, additional workpieces 200 and their possible gripping positions for gripping the workpiece 200 are recorded and this data is stored (centrally).

[0050] Fig. 3 shows a flowchart of an embodiment of the method according to the invention for determining a gripping position for gripping a workpiece.

[0051] First, a plate-shaped device (plate 100) with a projection 110 of at least one gripping movement of a gripper 300 is provided (step S102) in order to carry out the teaching of the workpiece 200, which is still unknown to the gripper 300.

[0052] In the subsequent step (S103), the workpiece 200 is positioned with respect to the plate-shaped device (plate 100) in such a way that an outer contour of the workpiece 200 intersects the projection 110 of at least one gripping movement.

[0053] This is important in order to detect possible contact points of the gripper 300 for gripping the workpiece 200. Furthermore, this allows the user / worker to recognize where the gripper 300 would grip the workpiece 200 and can make a correction if necessary.

[0054] Now, the detection (step S104) of intersection points of the outer contour of the workpiece 200 with the projection 110 of at least one gripping movement takes place in order to determine the contact points of the gripper 300 with the workpiece 200.

[0055] Subsequently, the gripping position for gripping the workpiece 200 is determined from the detected intersection points so that the gripper 300 can grip the workpiece 200.

[0056] The above steps can be repeated as often as desired, depending on how many gripping positions are to be taught to the gripper 300 for the corresponding workpiece 200.

[0057] Fig. 4 schematically shows the detection of the workpiece 200 in relation to the device according to the invention (plate 100) by the detection device 400 for determining a workpiece coordinate system 220.

[0058] In this case, a local coordinate system 120 of the plate 100 is essentially used to determine the workpiece coordinate system 220. This is done by detecting the outer contour of the workpiece 200 and the projection 110 of the gripping movement located on the surface of the plate 100 by means of the detection device 400.

[0059] The projection 110 essentially specifies the position of the local coordinate system 120. For example, the local coordinate system 120 can be provided relatively centrally on the surface of the plate 100, in particular in conjunction with the projection 110 of the gripping movement. Thus, as in Fig. 4 shown, for example, the local coordinate system 120 can be located at the intersection point of the two straight lines of the projection 110 of the gripping movement, or, if for example only one straight line is present as projection 110 on the surface of the plate 100, it can be provided centrally on the projection 110 and / or centrally on the plate 100.

[0060] Furthermore, the local coordinate system 120 can also be defined on the basis of the intersection points of the outer contour of the workpiece 200 with the projection 110 of the gripping movement (the intersection points simultaneously define the points for gripping the workpiece 200 by the gripping elements 310) and, if appropriate, in conjunction with the position of the projection 110 of the gripping movement on the surface of the plate 100.

[0061] If the outer contour of the workpiece 200 and the local coordinate system 120 are now recorded, the measured height of the workpiece 200 (as in Fig. 4 A z-offset may occur (shown in the z-direction), so that the local coordinate system 120 is shifted from the surface of the plate 100 to the upper side of the workpiece 200. This may take place, for example, in a control unit 410 of the detection device 400.

[0062] The local coordinate system 120 shifted in this way results in the workpiece coordinate system 220, on the basis of which the gripper 300 can be brought / moved in relation to the workpiece 200 in order to grip the workpiece 200. The gripper coordinate system present in the gripper 300 is set in relation to the defined workpiece coordinate system 220, and this relation is saved for the corresponding workpiece 200 or for the corresponding position of the workpiece 200. If a workpiece 200 or a contour of a workpiece 200 is now recognized, the gripper 300 can be positioned accordingly relative to the recognized workpiece 200 (based on the saved relation between the workpiece coordinate system 220 and the gripper coordinate system).

[0063] In addition to the already mentioned properties of the height and contour of the workpiece 200, further properties and geometric details of the workpiece 200 can also be recorded, such as a diameter of the workpiece 200, or certain shape descriptors of the workpiece 200, etc.

[0064] These may be important for the subsequent recognition of the workpiece 200 by the detection device 400 and for the corresponding assignment of the desired gripping positions by the gripping elements 310.

[0065] In addition, it is advantageous if the detection of the intersection points of the outer contour of the workpiece 200 with the projection 110 of the gripping movement for different positions of the workpiece 200 on the surface of the plate 100 takes place, since, for example, it cannot be ruled out that the workpiece 200, instead of upright on the surface of the plate 100 (as in Fig. 4 shown), can lie on its side, so that other points for gripping the workpiece 200 by the gripping elements 310 may need to be defined / determined.

[0066] It is therefore advantageous if the method according to the invention for detecting a gripping position is carried out for several different layers or for several desired gripping positions.

[0067] Fig. 5 shows schematically various workpieces 200 as they are positioned in relation to the device according to the invention (plate 100) and intersect the projection 110 of the gripping movement.

[0068] Figure a) shows a cylindrical workpiece 200, which is positioned essentially centrally on the plate 100 at the intersection point of the straight lines of the projection 110 of the gripping movement. The detection device 400, which in this example is provided directly on the gripper 300, can now detect the workpiece 200 (including the contour and other geometric details) as well as the projection 110 of the gripping movement and accordingly perform a z-offset for establishing / defining the workpiece coordinate system 220, based on which the gripper 300 can grip the workpiece 200.

[0069] Figures b) to d) now show further exemplary workpiece shapes, with figures c) and d) showing the same workpiece 200, but the relative position of the workpiece 200 relative to the projection 110 of the gripping movement or relative to the plate 100 being different. It is always up to the user how to position the workpiece 200 on the plate 100 and thereby influence the gripping position(s).

[0070] In all cases, as described in Figure a), the characteristics of the workpiece 200 and the projection 110 of the gripping movement required to define the gripping position are recorded.

[0071] Fig. 6 shows schematically a plurality of different and partially combined projections 110 of gripping movements that can be provided on the device according to the invention (plate 100).

[0072] Figure a) shows a triplet of three converging straight lines that meet at a single point, which exemplifies the gripping movement of a three-finger gripper. Such grippers can be used particularly for cylindrical workpieces 200, since the three contact points on the outer surface of the cylindrical workpiece 200 enable secure gripping. Here, for example, the local coordinate system 120 of the plate 100 can be located essentially centrally at the intersection point of the three straight lines.

[0073] Figure b) now shows an intersection of two straight lines, which in the specific example are essentially perpendicular to each other, but can also assume other relative positions. The two straight lines can characterize the gripping movement of a four-finger gripper, for example, to utilize as many points as possible to grip the workpiece 200, as can be advantageous with heavy workpieces, or to ensure stable transport of the workpiece 200 without changing the position of the workpiece 200 relative to the gripper 300. The local coordinate system 120 of the plate 100 can, for example, lie essentially centrally at the intersection point of the two straight lines.

[0074] However, the two crossed straight lines can also be used for a two-finger gripper that can grip the workpiece 200 from two different sides / directions. The detection device 400 would detect the intersection points between the outer contour of the workpiece 200 (for example, a cube centered on the intersection point of the straight lines) and the projection 110 of the gripping movement and could then define two different ways for the gripper 300 to grip the workpiece 200 based on the workpiece coordinate system 220.

[0075] Figure c) now shows a straight line, which essentially characterizes the gripping movement of a two-finger gripper. Here, for example, the local coordinate system 120 of the plate 100 can be located essentially centrally on the straight line.

[0076] Figure d) now shows a combination of all three aforementioned projections 110 of gripping movements, whereby here too, the local coordinate system 120 of the plate 100 can, for example, be located essentially centrally at the common intersection point of the straight lines. This embodiment of the projection 110 of the gripping movement is particularly advantageous because all configurations of gripping movements or all types of grippers 300 can be represented on one plate 100, and a separate plate 100 or separate projection 110 of the gripping movement is not required for each gripper type.

[0077] It should be noted at this point that the mentioned or shown projections 110 of the gripping movement are not to be understood as restrictive, but can be supplemented by further possibilities of gripping movements, in particular also by partial movements of the gripping movements mentioned / shown so far.

[0078] Fig. 7 shows schematically a changing device (gripper 300) on a robot 3000 for gripping a workpiece 200 from a pallet 4000.

[0079] In this case, one of the three workpieces 200 present on the pallet 4000 is inserted into the machine tool 1000 by the robot 3000, for example, wherein the workpiece 200 or the contour of the workpiece 200 was previously taught to the robot 3000 by the method according to the invention for detecting a gripping position.

[0080] First, the workpiece 200, in particular its outer contour, is detected by the detection device 400 and compared with already known values, possibly stored in a storage unit 2000 (not shown here, see Fig. 2 ) stored workpieces / contours. If the workpiece 200 or the contour of the workpiece 200 is known, a control device (for example, the control unit 410 of the detection device 400) recognizes the present workpiece 200.

[0081] Thereafter, the gripper 300 (in particular the gripper coordinate system) is brought into the relationship to the workpiece coordinate system 220 required for gripping the detected workpiece 200 (for example, by moving and / or rotating the gripper 300 relative to the workpiece 200) until the workpiece coordinate system 220 and the gripper coordinate system have assumed the required relationship to one another. Thereafter, the actual gripping of the respective workpiece 200 can take place, and the gripping elements 310 (as in Fig. 1 described) can close.

[0082] The now gripped workpiece 200 can now be transported by the robot to the machine tool 1000 and inserted there. However, it should be noted at this point that the described gripping of the workpiece 200 is not limited to a pallet 4000. Workpieces 200 can be gripped from any surface (e.g., from a conveyor belt, etc.) or from any container (e.g., wire mesh boxes, etc.). The gripped workpieces 200 can also be inserted into a device other than a machine tool 1000; for example, they can be relocated or simply sorted.

[0083] Examples or embodiments of the present invention and their advantages have been described in detail above with reference to the attached figures.

[0084] It should be emphasized again that the present invention is in no way limited or restricted to the exemplary embodiments and their embodiment features described above, but further comprises modifications of the exemplary embodiments which are encompassed by modifications of the features of the described examples or by combination of one or more of the features of the described examples within the scope of protection of the independent claims. LIST OF REFERENCE SYMBOLS

[0085] 100 plates 110 Projection of the gripping movement (movement of gripping elements 310 of the gripper 300) 120 local coordinate system of the plate 200 workpiece 220 Workpiece coordinate system 300Gripper 310Gripping elements 400 Recording device 410 Control unit 1000Machine tool 2000Storage unit 3000 Robot / change device 4000 range

Claims

1. Method for determining a gripping position for gripping a workpiece (200), characterized by the steps: - providing a plate-shaped device (100) having a projection (110) on a surface which reflects at least one movement of gripping elements (310) of a gripper (300), wherein the projection (110) differs in color from the surface of the plate-shaped device (100) and / or comprises depressions in the surface; - positioning the workpiece (200) in relation to the plate-shaped device (100) such that an outer contour of the workpiece (200) intersects the projection (110) of the at least one movement of the gripping elements (310) of the gripper (300); - detecting a workpiece geometry of the workpiece (200), comprising the outer contour of the workpiece (200); - detecting intersection points of the outer contour of the workpiece (200) with the projection (110) of the at least one movement of the gripping elements (310) of the gripper (300); - storing the detected workpiece geometry and the detected intersection points of the outer contour of the workpiece (200) with the projection (110) of the at least one movement of the gripping elements (310) of the gripper (300); - determining the gripping position for gripping the workpiece (200) from the detected intersection points, wherein a workpiece coordinate system (220), which defines the gripping position for gripping the workpiece (200), is determined on the basis of the detected intersection points of the outer contour of the workpiece (200) with the projection (110) of the at least one movement of the gripping elements (310) of the gripper (300), and a relation between the determined workpiece coordinate system (220) and a gripper coordinate system (300) of the gripper (300) is determined and stored for the workpiece (300).

2. Method according to Claim 1, characterized in that the projection (110) of the at least one movement of the gripping elements (310) of the gripper (300) defines a local coordinate system (120) of the plate-shaped device (100), wherein the workpiece coordinate system (220) is determined on the basis of the local coordinate system (120) and the detected workpiece geometry.

3. Method according to Claim 2, characterized in that the local coordinate system (120) is defined between the detected intersection points of the outer contour of the workpiece (200) with the projection (110) of the at least one movement of the gripping elements (310) of the gripper (300).

4. Method according to one of the preceding claims, characterized in that the detected intersection points are contact points of the gripper (300) at which the workpiece can be gripped by the gripper (300).

5. Method according to one of the preceding claims, characterized in that the detected workpiece geometry of the workpiece (200) comprises: a height of the workpiece (200) positioned in relation to the plate-shaped device (100), and / or a diameter, and / or shape descriptors of the workpiece (200).

6. Device for determining a gripping position for gripping a workpiece (200) for use in a method according to one of Claims 1 to 5, having a detection device (400) which is set up to determine the gripping position for gripping the workpiece (200), characterized by: - a plate-shaped device (100) having a projection (110) on a surface which reflects at least one movement of gripping elements (310) of the gripper (300), wherein the projection (110) differs in color from the surface of the plate-shaped device (100) and / or comprises depressions in the surface; wherein the detection device (400) is set up to detect and store a workpiece geometry of a workpiece (200) which is positioned on the plate-shaped device (100) and comprises an outer contour of the workpiece (200), to detect and store intersection points of the outer contour of the workpiece (200) with the projection (110) of the at least one movement of the gripping elements (310) of the gripper (300), and to determine the gripping position for gripping the workpiece (200) from the detected intersection points, and is set up to determine a workpiece coordinate system (220), which defines the gripping position for gripping the workpiece (200), on the basis of the detected intersection points of the outer contour of the workpiece (200) with the projection (110) of the at least one movement of the gripping elements (310) of the gripper (300), and to determine a relation between the determined workpiece coordinate system (220) and a gripper coordinate system (300) of the gripper (300) and store for the workpiece (300).

7. Device according to Claim 6, characterized in that the projection (110) of the at least one movement of the gripping elements (310) of the gripper (300) comprises grooves or grooves.

8. Device according to one of Claims 6 to 7, characterized in that the projection (110) of the at least one movement of the gripping elements (310) of the gripper (300) has the following form: the form of a straight line, the form of two intersecting straight lines, the form of two straight lines which intersect perpendicularly to one another, the form of three straight lines which converge and touch one another, the form of three straight lines which converge and touch one another and are substantially at the same angle to one another, and / or a combination of two or more of said shapes.

9. Method for gripping a workpiece (200), comprising: - providing the workpiece (200) to be gripped; - detecting an outer contour of the workpiece (200); - detecting the detected outer contour of the workpiece (200) on the basis of a known outer contour of a known workpiece, wherein the known outer contour of the known workpiece and the associated gripping position for gripping the known workpiece are detected by a method according to one of Claims 1 to 5; and - gripping the workpiece (200) by a gripper (300) on the basis of the detected outer contour of the workpiece (200) and the associated gripping position for gripping the workpiece.