Method for determining an absolute position of a mobile transport means on a work surface device, transport assembly, and work surface device

Abstract

The invention relates to a method for determining an absolute position of a mobile transport means (2) on a work surface device (3), wherein the work surface device (3) has at least two code segments (6), wherein the two code segments (6) are located directly adjacent to each other, wherein each of the code segments (6) has a coding of the local position on the code segment (6), wherein the at least two code segments (6) are entered in a common code map (10) of the work surface device (3) so that the global positions on the common code map (10) can be determined from the local positions on the respective code segments (6), wherein each of the code segments (6) provides items of code information, wherein the items of code information can be read by the mobile transport means (2), wherein the items of code information of the at least two code segments (6) jointly form a segment coding, wherein the segment coding forms an identification of at least one of the code segments (6) in the common code map (10), wherein the absolute position of the mobile transport means (2) in the common code map (10) and / or in the work surface device (3) is determined on the basis of the identified code segment (6) and the coding of the local position on the identified code segment (6).

Description

[0001] Description

[0002] title

[0003] Method for determining an absolute position of a transport vehicle on a work surface device, transport arrangement and work surface device

[0004] State of the art

[0005] The document DE 10 2016 216 196 A1 , which forms the closest prior art, discloses a sensor system with at least one evaluation unit, which has an optical sensor unit for recording at least one image of a marking area with optical markings, wherein the optical markings comprise six items of position information about their positions in the marking area, wherein the evaluation unit is designed to determine the position of the optical sensor unit with respect to the marking area in up to six positional degrees of freedom on the basis of the at least one image.

[0006] Disclosure of the invention

[0007] Autonomously driving transport vehicles are the key to flexible production and logistics applications. In these applications, a master computer specifies a single transport route for the transport vehicles, which they can then travel autonomously, i.e. without detailed control, in order to carry out their assigned transport function. In addition to the complex task of planning the transport route and controlling the transport vehicles, the transport vehicles should always be informed of their own position in order to be able to manage the transport route autonomously. The subject matter of the invention is a method for determining an absolute position having the features of claim 1, a transport arrangement having the features of claim 12 and a work surface device having the features of claim 13. Preferred or advantageous embodiments of the invention can be found in the subclaims, the following description and the attached figures.

[0008] The subject matter of the invention is a method for determining an absolute position, in particular a reference position, of a transport vehicle on a work surface device.

[0009] The absolute position can be determined, for example, in a global coordinate system, such as a world coordinate system, which is specified by the transport environment. In the simplest case, the absolute position can be, for example, two-dimensional information, such as X and Y coordinates, three-dimensional information that additionally has a Z coordinate, or even up to 6D information, wherein at least one, two, or three independent angles of rotation of the transport vehicle relative to the work surface device and / or in the global coordinate system are also determined.

[0010] The transport vehicle can in particular be designed as an autonomous transport vehicle. In particular, the respective transport vehicle is designed to be free of people. Alternatively or additionally, the transport vehicle is designed to exclusively transport goods, products, workpieces, or the like. For example, the transport vehicle is implemented as a transport robot or as a flying or hovering vehicle. Preferred embodiments of the transport vehicle are AGV (Automated Guided Vehicle) and / or FTF (Driverless Transport Vehicle). In particular, the transport vehicle is designed as a vehicle that can transport small quantities quickly over short distances and is preferably used for transport within a production line. Optionally, trains consisting of a train vehicle and a series of trailers are also used as transport vehicles.

[0011] The work surface device has at least two code segments. Preferably, the work surface device has at least five, in particular at least 10, and especially at least 50 code segments. The at least two code segments are arranged directly adjacent to one another. In particular, they have a common transition area. The transition area can be continuous, but it can also be provided that a gap, in particular less than 10 cm, especially less than 2 cm, is provided between the code segments.

[0012] Each of the code segments has a coding of the local position on the associated code segment. The local position can be configured analogously to the absolute position, with the difference that the local coordinate system of the respective code segment is used as the reference coordinate system. In particular, the local coordinates of a position on a surface can be determined. For this purpose, the surface is covered, for example, in a grid-like manner with optically detectable codes, each of which encodes the spatial coordinates of the code itself. This creates a so-called coding on the surface.

[0013] The transport vehicle preferably has a sensor device for reading the coding of the local position from the code segment. The sensor device can be based on any physical operating principle; for example, it can be electrical and / or magnetic. Preferably, the coding is embodied as an optical coding and / or the sensor device is embodied as an optical sensor device, such as a camera.

[0014] The coding can be implemented as a plurality of local codes, such as QR codes. The coding is preferably implemented as described in the document DE 10 2016 216 221 A1, the disclosure of which regarding the coding, and in particular the angle coding, is incorporated by reference into the present disclosure.

[0015] The at least two code segments are entered in a common code card of the work surface device, in particular in the correct location and / or position. A code card is understood in particular to be a data model which has the properties described below. It is not absolutely necessary for the code card to actually be designed as a 2D plan; it is also possible for the code card to be implemented as a data set. The at least two code segments and in particular all code segments involved are entered in the common code card in such a way that the global positions on the common code card and / or on the work surface device can be determined from the local positions on the respective code segments. The global positions preferably form the absolute position on the code card and thus on the work surface device.Thus, in the simplest case, it is only necessary for the code card that the respective local coordinate systems are determined to the global coordinate system of the code card and / or the work surface setup / or the world coordinate system. The code segments can be recorded during setup by a mobile transport vehicle during setup and entered into the code card.

[0016] For example, surfaces with variable geometries are provided with code fields. This is especially true when transport routes are constructed from individual route segments (straight lines, curves, etc.) as code segments and are later modified. In this case, it is not possible for the coding to directly encode an absolute position, as the absolute position changes depending on the route geometry being constructed. By integrating them into the code card, the code segments can be placed as desired.

[0017] Each of the code segments provides code information, which can be read by the transport vehicle. Optionally, the code information can include or form the coding of the local position. Alternatively, the code information can be additional information about the local positions on the code segment. A combination of the local positions and the additional information is also possible.

[0018] The code information of at least two code segments together forms a segment code. Thus, the code information of the participating code segments is necessary to form the segment code. The segment code forms an identification of at least one of the code segments in the shared code card. After reading the segment code, it is thus known which code segment the transport vehicle is located on. Preferably, the code segment that represents the current position of the transport vehicle on the work surface device is selected.

[0019] Based on the identified code segment and the coding of the local position on the identified code segment, the absolute position of the transport vehicle is determined in the common code card and / or on the work surface device.

[0020] Thus, position determination is not achieved by reading a single piece of code information, but by combining code information from neighboring code fields. This allows code fields to be redundant, i.e., multiple in the system, and still allow the determination of a position in an absolute global coordinate system.

[0021] It is important to consider that, for example, in the work surface setup, which is composed of several code segments for practical reasons, the determination of the absolute position must be carried out depending on the respective code segment. However, from the perspective of the transport vehicle, it is initially impossible to distinguish which code segment it is located on without additional information, and thus it can only determine the local position.

[0022] During normal operation of the transport vehicle, however, the code segment it is located on is known based on the planned and executed transport route. Regardless of this, or for example, during initial activation or reactivation of the transport vehicle, the transport vehicle must first be informed of its absolute position or at least the current code segment.

[0023] The absolute position can be determined, for example, by a reference run, designed as a search run by the transport vehicle. During the reference run, the segment coding is read out, allowing the transport vehicle to determine the absolute position as its own position. This makes it possible for the transport vehicle, if the information technology loses its absolute position, to locate itself on the work surface device using a reference run and determine its own position as an absolute position.

[0024] Segment coding initially assumes exactly two code segments. However, in further developments, code information from more than two code segments can also be used to generate the segment coding. For example, three, four, or more code segments can be used as participating code segments.

[0025] In particular, it is provided that each of the code information of the code segments involved in the segment coding carries a non-empty information part of the segment coding. Thus, it is not sufficient to capture the code information of only one code segment. Rather, a method is chosen in which a combination of the code information of the code segments involved leads to the segment coding. The code information each forms true and / or non-empty, in particular non-redundant, subsets of the segmentation coding.

[0026] This design is based on the idea that, while it would be possible in principle to insert the segment coding as data into each code segment, this would have the disadvantage that all code segments would have to have different, individualized data for unique segment coding and could therefore only be produced as individual pieces. By processing code information from the participating code segments, a segment coding is used that can, on the one hand, use general, non-individualized code segments and, on the other hand, reliably determine the absolute position.

[0027] In a preferred embodiment of the invention, the code information for the segment coding is embodied as the coding of the local position. It is assumed that a discontinuity, in particular a jump in the read local positions, occurs in the transition region between the at least two code segments on the transport path. In particular, the code segments are not arranged in the correct position relative to one another with respect to their local coordinate systems. Preferably, the transition regions form discontinuities, in particular jumps in the local positions. In particular, the discontinuities are different in all transition regions of the work surface device and are thus clearly identifiable. This boundary condition is implemented virtually automatically during the manufacture of the work surface device.In the very unlikely event that a discontinuity occurs multiple times, this will be detected during the setup run or in the code card and can be corrected.

[0028] As soon as the transport vehicle detects such a discontinuity based on crossing a transition area, the segment coding can be generated. The discontinuity is a unique characteristic both of a change in the code segments and of the code segments involved.

[0029] A simple, possible implementation is a method that detects the discontinuity of the codes or coded coordinates when passing from a first code segment to the next code segment. If the combination of the last coordinate recorded on the first code segment and the first coordinate recorded on the next code segment is unique, the combination can be used to determine which code segment the transport vehicle is located on (identity of the next code segment). Thus, the identity of the next code segment can be determined without explicitly storing the identity in coding.

[0030] For example, the segment coding can be formed by an offset of the local positions of the at least two code segments and / or by the offset of the local coordinate systems of the at least two code segments on the transport path of the transport vehicle. On the one hand, it is possible for the code segments to be arranged only linearly offset from one another. In this case, a common offset dimension is valid for each transition area, which is formed by the relative offset. If, on the other hand, the code segments are randomly offset from one another, for example, additionally rotated from one another or arranged with an irregular, for example wedge-shaped, transition area, the segment coding is formed by the combination of the local positions of the at least two code segments on the transport path of the transport vehicle when crossing the transition area. In a preferred embodiment of the invention, the code segments are designed as free forms.For example, the code segments can be formed from different track sections, such as straight sections, curved sections, etc., like a toy train. This allows a work surface setup for any application to be installed particularly quickly using the freeforms. Subsequently, a setup run is performed, for example, to enter the local positions of the individual code segments and / or the local coordinate systems into the code card.

[0031] In a further development of the invention, the work surface device has a plurality of code segments in different variants. The code segments of a variant are each identical in construction, in particular with identical coding, wherein each variant carries a variant coding as coding information. This further development has the advantage that the code segments can be produced in a limited number of variants and, within this variant, each with an identical construction, so that the manufacturing costs for the code segments are particularly low. Furthermore, it has the advantage that if a code segment is damaged, it can be replaced with a code segment of the same variant. The segment coding is formed or at least co-formed by a combination of the variant coding of the at least two code segments.

[0032] In a possible, simple embodiment, the different variants of the code segments are laid out in the design of the work surface device in such a way that a transition between two code segments with the same segment coding, ie with the same combination of variant coding, is only present once in the work surface device.

[0033] While this approach is feasible, it requires a large number of different variants if the work surface setup is to be comparatively large. Against this background, it is proposed that the code segments carry an angle coding, with the segment coding being formed by a combination of the variant coding and a combination of the angle coding. For the preferred case where the angle coding encodes four angles as angular information, for example, 0°, 90°, 180°, 270°, a significantly smaller number of variants is required compared to segment coding, which relies exclusively on variant coding. With angle coding, the code information always comprises one piece of angle information.

[0034] In a preferred embodiment of the invention, the code segments are designed as tiles, in particular as square or rectangular tiles. The tiles can be made of any material. Alternatively, the tiles are to be understood as virtual tiles only, whereby a plurality of tiles can be applied to a common carrier. The tiles are particularly easy to install, maintain, and / or replace during production. The tiles make it particularly easy to implement the combination of variant coding and angle coding, since when laying out the work surface device, the tiles are installed according to the planned segment coding.

[0035] In a further development of the process, the production of the work surface device can thus be simplified. The work surface device is not manufactured in one piece, but rather "tiles" with codes as code segments are produced. The geometry of the tiles is not specified; ideally, it should allow for a seamless layout of the surface and have at least one axis of symmetry. A square geometry is assumed here as an example. Note: It is possible for the tiling to have gaps, provided the resulting inaccuracies can be compensated or tolerated.

[0036] When tiling a work surface, any of the following rules can be followed:

[0037] In principle, only two adjacent tiles and / or adjacent code segments are necessary to determine the absolute position. However, this limits the coding options. In a preferred embodiment of the invention, a plurality of tiles form a coding field, wherein the coding field carries the segment coding. For example, the coding field has four tiles, wherein the four tiles are arranged in a rectangle, in particular a square. During segment coding, all transitions of the tiles are used, so that four transition areas are considered for reading the segment coding. By using four transition areas, variant coding, and angle coding, work surface devices with unique segment codings with a large area can be produced.

[0038] In a simplified work surface setup, each coding field is provided with an orientation tile and several identification tiles. The orientation tile has a variant coding and an angle coding, with the angle coding being aligned the same for all orientation tiles of the work surface setup. The orientation tile thus carries the orientation of the work surface setup as code information and can be easily identified by the transport vehicle.

[0039] The identification tiles carry the variant coding and the angle coding, with the identification tiles being distributed and twisted and / or rotated in the coding field such that all coding fields of the work surface device have a different combination of angle coding of the identification tiles relative to the orientation tile. If the angle coding comprises four values, 4x4x4 different segment codings must be generated. If this does not yet achieve sufficient coding depth for the work surface device, variant coding can be used as an additional means to increase the coding depth.

[0040] In a preferred embodiment of the invention, the variant coding is designed as a color coding of the tiles. The color coding allows the tiles to be laid in the correct position during the construction of the work surface device and to be visually checked by the color coding being easily read by the human eye. Alternatively or additionally, it is preferred that the angle coding be readable by the human eye in order to lay out the tiles in the correct angular position. A further subject matter of the invention relates to a transport arrangement with the work surface device and with at least one transport vehicle, wherein the transport vehicle is designed in terms of circuitry and / or programming to carry out the method for determining the absolute position as described above. The method can be carried out locally on the transport vehicle or via a digital data processing device, e.g.Cloud with which the transport vehicle is connected for data purposes.

[0041] A further subject matter of the invention relates to a work surface device for carrying out the method as described above, in particular in the transport arrangement as described above, wherein the work surface device has a plurality of tiles with a coding of the local position and a variant coding, wherein the tiles are laid out in the work surface device so that the segment coding is uniquely formed in the work surface device.

[0042] Further features, advantages, and effects of the invention will become apparent from the following description of preferred embodiments and the accompanying figures. These show:

[0043] Figure 1 is a schematic representation of a transport arrangement as an embodiment of the invention;

[0044] Figure 2a shows different variants of code segments for the transport arrangement in Figure 1;

[0045] Figure 2b shows a work surface device with code segments from different variants of Figure 2a for the transport device in Figure 1;

[0046] Figure 3 is a flow chart describing the method for determining an absolute position of a transport vehicle on a work surface device.

[0047] Figure 1 shows a schematic plan view of a transport arrangement 1 for a plurality of transport vehicles 2 on a work surface device 3. The transport arrangement 1 has a master computer device 4, which is designed to specify transport routes 5 for the transport vehicle 2 and to transmit them to the transport vehicle 2. The transport vehicle 2 is designed as an autonomous transport vehicle 2, which can travel along the transport route 5 autonomously. To travel along the transport route 5, the transport vehicle 1 requires its current own positions.

[0048] The work surface device 3 has a plurality of code segments 6, wherein the code segments 6 are directly adjacent to one another and separated from one another by a transition region 7. The code segments 6 each have a planar coding of the local position on the code segment 6. The local position is designed, in particular, as an absolute position in a local coordinate system 8. As shown in the exemplary embodiment, the coding is designed, for example, as an optical coding in the form of a plurality of QR codes 9. However, alternatives are possible which can also encode absolute, local positions.

[0049] The transport vehicle 2 has a corresponding sensor device for detecting the coding, in particular the QR code 9. The code segments 6 are recorded in a common code card 10 with a global coordinate system 11, so that the local positions from the respective local coordinate systems 8 can be determined into the absolute positions in the code card 10 and thus on the work surface device 3.

[0050] In order to determine its own position, the transport vehicle 2 must, on the one hand, know the local position on the respective code segments 6 and, on the other hand, have information as to which code segment 6 the transport vehicle 2 is currently located in order to be able to determine the global position in the global coordinate system 11 of the code card 10.

[0051] For this purpose, segment coding is used, wherein the segment coding is composed of code information from adjacent code segments 6 in the transition region 7. In the exemplary embodiment in Figure 1, the code information is formed as a local position 12 on a preceding code segment 6 and a local position 13 on a subsequent code segment 6. The transition from the local position 12 to the local position 13 via the transition region 7 forms a discontinuity, in particular a jump, along the transport path 5.

[0052] On the one hand, the discontinuity arises from the fact that the code segments 6 are not positioned correctly relative to each other. This results in a natural discontinuity

[0053] However, it can also be provided that the different code segments 6 have a deliberate offset in the coding of the local positions, so that, for example, the first code segment 6 has its origin at a position [0;0], the second code segment 6 has its origin at [1000;1000], and the subsequent code segments 6 each have a further offset. This can create an artificial discontinuity.

[0054] From the local positions 12, 13 in the transition area 7, an offset along the transport path 5 of the transport vehicle 2 can thus be determined. This offset is unique in the code card 10, so that the offset forms a segment coding, which can be identified via the code card 10 as a look-up table. The segment coding assigns the correct code segment 6 in the code card 11 and, in addition, the local position in the code segment 6 to the local position 13, so that the absolute position of the transport vehicle 2 can be determined in the code card 10 and / or in the global coordinate system 11.

[0055] The offset can have the same offset value for each of the transition areas 7. However, it is also possible that the transition area 7—as indicated in the drawing—is wedge-shaped, so that a local offset value between the local positions must be evaluated and used as segment coding.

[0056] The local positions 12, 13 thus form code information from which the segment coding can be derived.

[0057] In the embodiment shown in Figure 1, the code segments 6 are each designed as track sections, which can be easily placed next to one another when designing the work surface device 3. For example, the code segments 6 are designed as movement primitives, such as:

[0058] - Straight

[0059] - Crossing

[0060] - Right angle

[0061] - 90° curve

[0062] - 180° curve

[0063] - 270° curve etc.

[0064] Figure 2a shows a plurality of code segments 6, which in this exemplary embodiment form six different variants. The code segments 6 of a variant are each identical in construction and, in particular, are designed with the same coding.

[0065] The code segments 6 shown in Figure 2a carry a variant coding and, in addition, an angle coding, so that their installation angle can be read. The code segments 6 are designed as tiles, which can be laid out flat in any desired shape as a work surface device 3.

[0066] Figure 2b shows an embodiment in which the work surface device 3 is limited to the outlined part of the overall area. Any other subareas can be added as needed. In the embodiment in Figure 2b, four code segments 6 each form a code field 14, which bears a segment code.

[0067] Each of the code fields 14 has one orientation tile 15 and three identification tiles 16. The orientation tiles 15 are arranged across the entire work surface device 3 with the same angular orientation (see arrow). If the transport vehicle 2 passes over such an orientation tile 15, the transport vehicle 2 can identify it based on the variant coding and read the angular information. Based on the angular information, the transport vehicle 2 can estimate the position of the code field 14 and, in particular, the three identification tiles 16.

[0068] During a search run, the transport vehicle 2 travels through all transition areas 7 between the four code segments 6 of the code segment 14. After passing over them, the transport vehicle 2 can read out a unique segment code based on the angle coding (see arrows) of the identification tiles 16 and, optionally, additionally, different variant codes of the identification tiles 16, and identify any code segment 6 of the code field 14, so that the absolute position in the code card 10 and / or the work surface device 3 can be determined by combining the identified code segment 6 with the local position on the identified code field 6.

[0069] The number of required transition areas 7 and the selection of codings for the code segments 6 can be made dependent on the application. This makes it possible to include any combination of code information:

[0070] - Local position

[0071] - Variant coding

[0072] - Use angle coding to determine the absolute position.

[0073] Figure 3 shows a flowchart of an embodiment of the method for determining an absolute position of the transport vehicle on the work surface device 3. In a step 100, code information from two adjacent code segments is read in by the transport vehicle 2. In a step 200, a segment coding for identifying a code segment 6 is formed on the basis of the code information. In a step 300, the segment coding is decoded via the code card 10 and in this way the code segment 6 is identified. In a step 400, the absolute position of the transport vehicle 2 in the code card 10 and / or on the basis of the identified code segment 6 and the local position of the transport vehicle 2 on the identified code segment 6 is determined. Work surface equipment 3.

Claims

Claims 1. A method for determining an absolute position of a transport vehicle (2) on a work surface device (3), wherein the work surface device (3) has at least two code segments (6), wherein the two code segments (6) are arranged directly adjacent to one another, wherein each of the code segments (6) has a coding of the local position on the code segment (6), wherein the at least two code segments (6) are entered in a common code card (10) of the work surface device (3) so that the global positions on the common code card (10) can be determined from the local positions on the respective code segments (6), wherein each of the code segments (6) provides code information, wherein the code information is readable by the transport vehicle (2), wherein the code information of the at least two code segments (6) together form a segment coding,wherein the segment coding forms an identification of at least one of the code segments (6) in the common code card (10), wherein the absolute position of the transport vehicle (2) in the common code card (10) and / or the work surface device (3) is determined on the basis of the identified code segment (6) and the coding of the local position on the identified code segment (6).

2. Method according to claim 1, characterized in that each of the code information carries a non-empty information part of the segment coding.

3. Method according to claim 1 or 2, characterized in that the code information is formed as the coding of the local position.

4. Method according to claim 3, characterized in that the segment coding is formed by an offset of the local positions of the at least two code segments.

5. Method according to one of the preceding claims, characterized in that the code segments are designed as free forms.

6. Method according to one of the preceding claims, characterized in that the work surface device (3) has a plurality of code segments (6) in different variants, wherein the code segments (6) of a variant are each identical in construction, wherein each variant carries a variant coding as coding information, wherein the segment coding is formed or at least co-formed by the combination of the variant coding of the at least two code segments.

7. Method according to claim 6, characterized in that the code segments (6) carry an angle coding, wherein the segment coding is formed by the combination of the variant coding and the combination of the angle coding.

8. Method according to one of the preceding claims 6 or 7, characterized in that the code segments (6) are designed as tiles.

9. Method according to one of the preceding claims, characterized in that a plurality of tiles form a coding field (14), wherein the coding field (14) carries the segment coding.

10. Method according to claim 9, characterized in that each coding field has an orientation tile (15) and a plurality of identification tiles (16), wherein the orientation tile (15) carries a variant coding and an angle coding, wherein the angle coding is aligned in the same way for all orientation tiles (15) of the working field device (3) and wherein the angle coding is distributed in the identification tiles (16) such that all Coding fields (14) of the work surface device (13) have a different combination of angle codings of the identification tiles (16) as segment coding.

11. Method according to one of claims 6 to 10, characterized in that the variant coding is designed as a color coding of the tiles.

12. Transport arrangement (1) comprising the work surface device (3) and at least one transport vehicle (2), wherein the transport vehicle (2) is designed in terms of circuitry and / or programming to carry out the method according to one of the preceding claims 13. Work surface device for carrying out the method according to one of claims 6 to 11, characterized in that the work surface device (3) has a plurality of code segments with a coding of the local position and a variant coding, wherein the code segments (6) are designed in the work surface device (3) so that the segment coding is uniquely formed in the work surface device (3).

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