System for transporting objects in a plant

Abstract

The present invention relates to a system (100) for determining the position of vehicles in a plant, in particular a packaging machine plant, comprising at least one vehicle (12) configured to move in the working environment, a drivable surface (16) on which the at least one vehicle (12) moves, and at least one camera unit (12a) configured to detect at least the drivable surface (16) in order to determine the position of the at least one vehicle (12) within the plant (10), wherein the drivable surface (16) is provided on its upper surface with a pattern in the form of a binary-coded continuous code in two dimensions, which can be detected by the at least one camera unit, or wherein the drivable surface is provided with a periodic, pseudo-random pattern in two dimensions, and the at least one camera unit (12a) orThe invention relates to a control unit operationally coupled to at least one camera unit for performing a spectral analysis of the captured pattern. Furthermore, the invention relates to a system (10) comprising such a system (100) and a method for determining the position of a vehicle (12) in such a system (10).

Description

[0001] The present invention relates to a system for determining the position of vehicles in a plant, in particular a packaging machine plant, as well as such a plant and a method for determining the position of a vehicle in such a plant.

[0002] In systems with multiple stations, and especially in packaging machine systems, the purpose is generally to supply objects to the individual stations in a predetermined sequence, where they are processed or handled accordingly. In the specific case of a packaging machine system, this involves the precise repositioning of product packaging, such as cartons, delivered by a production machine on a conveyor belt, which is done using so-called robotic lines.

[0003] In this process, open primary packaging, such as tray-shaped containers, which are erected and three-dimensionally fixed from flat cardboard blanks upstream but already within the machine, travel on a container conveyor, usually parallel to the product conveyor in the direction of travel through the packaging machine. Several transfer robots are typically arranged in series as handling units, each picking up one or more products from the product conveyor and transferring the primary packaging, such as the tray, onto the container conveyor.

[0004] Further downstream, these primary packages are often transferred in one or more layers into secondary packaging, such as open-topped cartons, which is also usually done using transfer robots. Even further downstream, these secondary packages are combined with tertiary packaging, for example, stacked on pallets, mostly also by robots. The necessary handling operations are carried out at the individual workstations within the packaging line, such as tray separators, blank separators, carton erectors, carton closers, tray fillers, carton fillers, palletizers, etc.

[0005] The transport system used for this purpose can include, in addition to the aforementioned product belt and / or container belt, i.e. conveyor belts, which usually extend over sections of the entire length of the packaging line, also rail-bound sleds, whereby these rails, which can be designed as physical or virtual non-visible guiding devices, usually also extend along the entire length of the packaging line.

[0006] Although in the latter solution the carriages can already move independently of each other along the guide rail, such transport systems are still comparatively inflexible, since these carriages, for example, cannot overtake each other, cannot deviate from the guide rails and are also relatively expensive to purchase, so that a limited number of carriages are used and thus the carriages do not yet offer any significant buffering capacity for, for example, packaging placed on them.

[0007] Especially when the underlying work order changes—not just the product being processed, but a fundamental change to the handling or processing tasks related to the product and / or packaging process—such known transport systems are unsuitable, as they require a complex reconfiguration of the conveyor belts or guide rails, or even a complete rebuild within the packaging machines. Furthermore, these transport systems are not designed to spontaneously remove defective products or outer packaging from the system at various points, unless they were specifically designed for such operations from the outset, which also entails considerable additional effort.

[0008] It should be noted that although the scenario described above mainly refers to a packaging machine system, similar requirements and tasks also arise in other types of systems with multiple stations, in which products are processed in different ways at individual stations and must therefore be transported between individual stations during the processing process.

[0009] For such tasks, some production plants and logistics facilities have meanwhile started using so-called driverless transport systems, in which driverless transport vehicles, which are often also referred to as FTF or AGV (Autonomous Guided Vehicle), transport objects or products, such as components or assemblies, from a warehouse to a workstation or between workstations, often also outside the secured machine frames of the workstation.

[0010] These AGVs are typically large and heavy, capable of carrying loads of 50 kg or more. Most importantly, they are usually autonomous vehicles equipped with a wide range of sensors and their own on-board control system, often including on-board navigation with position determination based on the environment via on-board cameras, as well as collision avoidance systems. This makes them expensive and complex to maintain. Furthermore, such systems typically include a central control unit, such as a control center, with which the AGVs communicate wirelessly and from which they receive, for example, work orders or information about their own positions within the facility.

[0011] Most AGVs, however, independently determine their spatial orientation using sensors and reference points and transmit this information to the central control system, which usually specifies transport orders with a start point and destination point as well as a start time and destination time, but often leaves the navigation in between to the on-board control of the AGVs, as well as collision prevention to be carried out in real time based on locally acquired information about the environment of the respective vehicles.

[0012] To ensure the smooth execution of planned operational processes, the position tracking of the AGVs is of crucial importance, as only if these driverless transport vehicles can determine their own position with high accuracy can work orders be processed smoothly and according to schedule. As already mentioned, relatively complex and expensive systems are often used for this purpose, such as 2D cameras with subsequent image recognition, which enables a comparison with environmental data stored in a memory unit of the transport vehicle's control system in the form of map data.

[0013] Alternatively, an approach has been pursued to position dedicated markers in the relevant work environment, enabling transport vehicles to determine their own position within the system. However, it has become apparent that the markers used for this purpose, as well as the associated position data encoding, are sensitive to contamination. At the same time, a prerequisite for smooth and efficient workflows in such systems is that these markers can be reliably read even when the vehicles are traveling at high speeds. Furthermore, depending on the system size, a large addressable area is necessary to encode sufficiently large amounts of data in the markers.

[0014] Although the present invention will be discussed mainly in the context of driverless transport vehicles in a system with a plurality of stations, between which the transport vehicles transport objects, it is understood that it can generally be used for any vehicle in a corresponding working environment or system.

[0015] To solve this problem and to eliminate the disadvantages of the prior art described above, a system for determining the position of vehicles, for example driverless transport vehicles, in a plant, in particular a packaging machine plant, is proposed according to a first approach of the present invention. The system comprises at least one vehicle, for example a driverless transport vehicle, which is configured to move in the working environment, for example to transport objects between stations, a drivable surface on which the at least one vehicle moves, and at least one camera unit which is configured to detect at least the drivable surface in order to determine the position of the at least one vehicle within the plant.wherein the drivable surface is provided on its upper surface with a pattern in the form of a binary-coded continuous code in two dimensions, which can be detected by the at least one camera unit and in which the Hamming distance of neighboring codewords can in particular have the value 1.

[0016] Accordingly, in such a prototype of a system according to the invention, it is sufficient to read only the number of bits in the image captured by the corresponding camera unit, while it is not necessary to read a complete code sequence. In particular, the frequencies of the code in the two dimensions mentioned can differ.

[0017] Furthermore, it can be provided that the detection of the drivable surface by at least one camera unit is carried out in a triggered manner, whereby the recorded image data can then be analyzed and a current position of the vehicle derived from it. By choosing such a pattern in the form of a binary-coded continuous code in two dimensions, a high degree of redundancy can be achieved, resulting in high insensitivity to contamination. The corresponding code can be represented on the surface of the drivable surface, for example, by a visible "black on white" marking or vice versa. Moreover, such a pattern for a drivable surface is characterized by the fact that high-performance evaluation methods can be used within the framework of image analysis.

[0018] According to an alternative embodiment of the first aspect of the invention, which is also suitable for overcoming the aforementioned disadvantages of the prior art, a system for determining the position of vehicles in a plant, in particular a packaging machine plant, is proposed, comprising at least one vehicle, for example a driverless transport vehicle, which is configured to move in the working environment, for example to transport objects between stations, a drivable surface on which the at least one vehicle moves, and at least one camera unit which is configured to detect the drivable surface in order to determine a position of the at least one vehicle within the plant, wherein the drivable surface is provided with a periodic, pseudo-random pattern in two dimensions and the at least one camera unit or camera unit is configured to detect the position of the at least one vehicle within the plant.A control unit operationally coupled to at least one camera unit is configured to perform a spectral analysis of the captured pattern. In this process, the recorded image data can be analyzed, particularly in the frequency domain, and one-dimensional data can be extracted from the spectrum based on this spectral analysis.

[0019] Such a pattern is also characterized by its robustness against dirt and obstacles and its large addressable area. In particular, it allows for rapid decoding because only one-dimensional data is used, and the increased addressable area is achieved by assigning a symbol to each feature. Depending on the area captured by the camera unit (i.e., the image size) and the corresponding number of features of the pattern depicted, a high degree of precision in position determination can therefore be achieved.

[0020] With both variants of the systems according to the invention described above, the detection of the drivable surface by the at least one camera unit can further enable the determination of an angle to a coordinate system of the surface, or more generally speaking, an alignment of the corresponding vehicle in the system with respect to arbitrarily selectable waymarks and directions.

[0021] Furthermore, the drivable surface can comprise a plurality of driving surface modules, which are provided on their upper surface with identical two-dimensional patterns that allow a unique determination of a position in a coordinate system of the respective driving surface module.

[0022] Thus, a simplification of the pattern used can be achieved, since only the area of ​​a corresponding driving surface module needs to be filled with a suitable pattern in a unique way, and furthermore, transitions between corresponding driving surface modules can be determined separately by the control unit of the transport vehicle, so that transitions of the vehicle from one driving surface module to another during a movement of it can be determined.

[0023] Accordingly, position data of the vehicle in question, located in the coordinate system of an individual track module, can be mapped to a coordinate system of the entire system, provided that the track module currently being traversed by the vehicle is known. For this purpose, the at least one transport vehicle can also include a localization unit capable of determining which of the track modules the vehicle is currently located on, particularly during vehicle startup or when a fault or similar issue is detected.

[0024] Following such an initial or interim determination of the currently traversed track module, the vehicle's current location can be tracked by monitoring transitions between track modules. This allows for the transfer of the corresponding local coordinate position of an individual track module to a global coordinate position of the entire system, as described above. Alternatively, other techniques for the basic localization of a transport vehicle on a specific track module with lower resolution are conceivable. For example, an external camera system could be used to detect vehicles and their positions on one of the track modules, and the vehicle could then be informed at a later time which track module it is currently on.

[0025] In this context, it is also conceivable that the drivable surface can comprise a plurality of driving surface modules with different dimensions, whereby driving surface modules with the same dimensions can have identical two-dimensional patterns among themselves in order to be able to represent essentially arbitrarily shaped driving surfaces in a corresponding system.

[0026] Furthermore, each vehicle can be assigned one of the camera units, which is operationally coupled to a control unit of the vehicle. This control unit is configured to determine the current position of the corresponding vehicle based on the road surface detected by the camera unit. According to the invention, it is also conceivable to provide at least one of the camera units outside the vehicles in the system. This camera unit can be configured to detect a section of the drivable surface and a vehicle located thereon, both with regard to determining the current position of the vehicle using the pattern on the road surface and with regard to determining, as already mentioned above, on which road surface module a vehicle is currently located in a corresponding embodiment.

[0027] Furthermore, the control unit of a corresponding vehicle can also access a map of the system stored in a memory unit, which allows the vehicle's position and, if applicable, orientation to be assigned to a coordinate system of the system. In this way, the vehicle can be directly integrated into its working environment, with the map potentially containing additional data such as drivable and impassable sections or obstacles to be avoided.

[0028] Furthermore, the system according to the invention can include a central control unit which is communicatively coupled with the at least one vehicle and, if applicable, stations in the system and is configured to coordinate the operation of the at least one vehicle and, if applicable, the stations.

[0029] Furthermore, the present invention relates to a system, in particular a packaging machine system, comprising a plurality of stations for handling objects, as well as a system according to the invention of the type just described. In this system, at least one of the stations can be configured to receive objects from or transfer them to the at least one transport vehicle.

[0030] According to a further aspect, the invention relates to a method for determining the position of a vehicle in such a system, comprising, during operation of the vehicle, detecting at least the drivable surface in order to determine the position of the vehicle in the system based on the pattern on the detected drivable surface. In the aforementioned embodiment, in which a plurality of driving surface modules provided with identical patterns are used, it is accordingly also possible, when the vehicle is put into operation or in similar situations in which such a determination is necessary, to determine on which of the driving surface modules the vehicle is currently located.

[0031] Furthermore, the procedure can include determining the orientation of the vehicle in the system in order to determine both the position and the orientation of the vehicle in relation to its surroundings.

[0032] Further features and advantages of the present invention will become even clearer from the following description of embodiments thereof, when considered together with the accompanying figures. These show in detail: Fig. 1: a schematic plan view of a plant according to the invention, in which a system according to the invention is used; and Fig. 2a to 2c different representations of in the system from Fig. 1. Samples used and associated analysis results.

[0033] In Fig. Figure 1 shows a purely schematic top view of a system according to the invention, which is generally designated by reference numeral 10, and which comprises an indicated system 100 according to the invention as well as a plurality of stations M1 to M4 for handling objects. The system 10 can, for example, be a packaging machine system, wherein at least some of the stations M1 to M4 can be configured to receive objects from or transfer them to driverless transport vehicles 12, the driverless transport vehicles 12 serving as vehicles within the meaning of the present invention.

[0034] The transport vehicles 12, of which for the sake of clarity in Fig. Figure 1 shows only a single unit, which together form part of the system 100 according to the invention and are generally designed to transport objects between stations M1 to M4 of the system or other transfer points. For this purpose, they are equipped with further components that enable their driverless operation, such as a vehicle control unit 12b for controlling the functions of the vehicle, a communication unit (not shown) for establishing a wireless communication link with a central control unit or control center 14, a drive system controlled by the vehicle control unit 12b, and sensor and safety systems for preventing collisions and the like with stationary objects, persons, or other vehicles.

[0035] The central control unit 14 of the plant 10 is designed to coordinate the operation of the transport vehicles 12 by means of work instructions and the like, and, if necessary, depending on the design of the plant 10 and the intended work processes, also the operation of stations M1 to M4 for improved integration of the components of the plant 10.

[0036] In this process, the transport vehicles 12 move on a drivable surface 16, which also forms part of the system according to the invention and which is composed of a plurality of driving surface modules 16a, of which in Fig. 1 is shown as an example only, and which are provided on their upper surface with an identical two-dimensional pattern, which can, for example, be printed onto the upper surface of the running surface modules 16a using a suitable dye. Here, the Fig. 2a and Fig. 2b different conceivable variants of such patterns, it should further be noted that different dimensions of driving surface modules may be provided, which, however, may have identical two-dimensional patterns.

[0037] In order to determine the position within the system 10 with high precision in order to process work and transport orders appropriately, the transport vehicles 12 are each equipped with camera units 12a, which are arranged to capture a predetermined section of the drivable surface 16. This predetermined section is accordingly in a fixed spatial relationship to the body of the corresponding transport vehicle 12, and by suitable image analysis of the two-dimensional pattern provided on the top surface of the corresponding driving surface module 16a, both the current position and an angle in a local reference system of the currently traversed driving surface module 16a can be derived.

[0038] The necessary image recognition and processing can be carried out, for example, by the vehicle control unit 12b or another control unit coupled to it, using algorithms that are known per se, particularly in the example from Fig. 2a the number of bits in the corresponding barcode is read, where the Hamming distance of adjacent codewords has the value 1.

[0039] In the example from Fig. In contrast, in 2b an analysis of the displayed pseudo-random pattern in the frequency domain is performed, a structured spectrum is derived from the periodicity of the pattern, and an interpolation is carried out on this basis to extract one-dimensional data from the two-dimensional spectrum. This data can now be analyzed independently of the code to determine the respective coordinate positions and an angle in a corresponding coordinate system, as shown in particular in the visualization of a corresponding spectral analysis in Fig. 2c is indicated.

[0040] In this context, it should also be noted that transitions from one of the driving surface modules 16a to an adjacent one can also be recognized and treated accordingly within the framework of the recording of the two-dimensional pattern, so that a transition to the local coordinate system of the now driven color surface module 16a is subsequently carried out.

[0041] Furthermore, it should be noted that the control unit of the transport vehicle 12, which is responsible for determining its position, also has access to a map of the system 10 stored in a memory unit. Therefore, if the position of the transport vehicle 12 in the local coordinate system of the currently traversed track module 16a and the identity of the track module 16a in question are known, a corresponding position in a global coordinate system of the system 10 can be derived. A similar principle applies to the orientation of the transport vehicle 12 on the corresponding track module 16a. For example, two Cartesian coordinates and one angular coordinate with respect to one of the coordinate axes can be used to describe the position and orientation of the transport vehicle 12 in both the local coordinate system of a currently traversed track module and the global coordinate system of the entire system.

[0042] For this purpose, it may also be necessary at certain times to determine on which of the track modules the transport vehicle 12 is currently located, for example if, during commissioning, its own position within the system 10 is initially unknown.

[0043] For this purpose, various approaches are conceivable. For example, the transport vehicles 12 could be equipped with a localization unit that allows position determination within the system 10 at low resolution. While this might not initially allow the vehicle to determine its own position with sufficient precision to execute work orders, it would at least allow the currently traversed driving surface module 16a to be determined. In alternative variants, it would also be conceivable, for example, to roughly determine the position of the transport vehicle 12, or to ascertain the currently traversed driving surface module 16a, using an external camera system 18 of the system 100 according to the invention, as shown schematically here, and to supply corresponding data to the transport vehicle 12.

Claims

[1] System (100) for determining the position of vehicles (12) in a plant (10), in particular a packaging machine plant, comprising: - at least one vehicle (12) which is equipped to move around in the work environment, - a drivable surface (16) on which the at least one vehicle (12) moves, and - at least one camera unit (12a) which is configured to detect at least the drivable surface (16) in order to determine a position of the at least one vehicle (12) within the facility (10), wherein the drivable surface (16) is provided on its upper surface with a pattern in the form of a binary-coded continuous code in two dimensions which can be detected by the at least one camera unit. [2] System (100) according to claim 1, wherein in the binary-coded continuous code the Hamming distance of neighboring codewords has the value 1. [3] System (100) according to claim 1 or 2, wherein the frequencies of the code differ in the two dimensions. [4] System (100) according to one of the preceding claims, wherein the detection of the drivable surface (16) by the at least one camera unit (12a) is carried out in a triggered manner. [5] System (100) for determining the position of vehicles (12) in a plant (10), in particular a packaging machine plant, comprising: - at least one vehicle (12) which is equipped to move around in the work environment, - a drivable surface (16) on which the at least one driverless vehicle (12) moves, and - at least one camera unit (12a) which is configured to detect at least the drivable surface (16) in order to determine a position of the at least one vehicle (12) within the system (10), wherein the drivable surface is provided with a periodic, pseudo-random pattern in two dimensions, and the at least one camera unit (12a) or a control unit operationally coupled to the at least one camera unit is configured to perform a spectral analysis of the detected pattern. [6] System (100) according to claim 5, wherein an extraction of one-dimensional data is carried out from the spectrum obtained by spectral analysis. [7] System (100) according to one of the preceding claims, wherein the detection of the drivable surface (16) by the at least one camera unit (12a) further enables a determination of an angle to a coordinate system of the drivable surface (16). [8] System (100) according to one of the preceding claims, wherein the drivable surface (16) comprises a plurality of driving surface modules (16a) which are provided on their upper side with identical two-dimensional patterns which enable a unique determination of a position in a coordinate system of the driving surface module (16a). [9] System (100) according to claim 7, wherein the drivable surface (16) comprises a plurality of driving surface modules (16a) with different dimensions, wherein driving surface modules (16a) with the same dimensions have identical two-dimensional patterns. [10] System (100) according to one of the preceding claims, wherein each of the vehicles (12) is assigned one of the camera units (12a) which is operationally coupled to a control unit (12b) of the vehicle (12) which is configured to determine the current position of the corresponding vehicle (12) on the basis of the road surface (16) detected by the camera unit (12a). [11] System (100) according to one of the preceding claims, wherein the control unit (12b) of the vehicle (12) further has access to a map of the system (10) stored in a memory unit, which enables the detected position and, if applicable, orientation of the transport vehicle to be assigned to a coordinate system of the system (10). [12] System (100) according to one of the preceding claims, further comprising a central control unit (14) which is coupled to the at least one vehicle (12) and optionally stations (M1 - M4) in the plant communication and is configured to coordinate the operation of the at least one vehicle (12) and optionally the stations (M1 - M4). [13] Plant (10), in particular packaging machine plant, comprising a plurality of stations (M1 - M4) for handling objects and a system (100) according to one of the preceding claims. [14] System (10) according to claim 13, wherein at least some of the stations (M1 - M4) are equipped to receive objects from or transfer them to the at least one vehicle (12). [15] Method for determining the position of a vehicle (12) in a plant (10) according to one of claims 13 and 14, comprising: - during a driving operation of the vehicle (12), detection of at least the drivable surface (16) in order to determine the position of the vehicle (12) in the system (10) based on the pattern on the detected drivable surface (16). [16] Method according to the preceding claim, further comprising determining an orientation of the vehicle (12) in the system (10).

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