METHOD FOR VERIFYING AND / OR MONITORING A LOAD HANDLING SYSTEM OF A CRANE AND CRANE COMPLETING A SYSTEM FOR VERIFYING AND / OR MONITORING A LOAD HANDLING SYSTEM OF THE CRANE

Abstract

Method for checking and / or monitoring a multi-component load handling system of a crane (10) designed for handling at least one load (6), in which a) using at least one ToF sensor (8) at least one point cloud of a work area is generated in which the load handling system is at least partially arranged, wherein the load handling system has one or more retroreflective markings (7) which reflect light emanating from the at least one ToF sensor (8) at least partially back onto the at least one ToF sensor (8), b) the at least one point cloud is processed, whereby at least one digital twin of at least one part of the load-bearing system is generated based on the at least one point cloud and c) an evaluation of the at least one digital twin is carried out, in which it is derived whether the at least one load (6) is handled correctly by the load handling system by ensuring that there is no misalignment of the at least one load (6) relative to the load handling system.

Description

[0001] The present invention relates to a method for checking and / or monitoring a load-handling system of a crane comprising several components and designed for handling at least one load. In the method, at least one point cloud of a working area in which the load-handling system is at least partially located is generated using at least one time-of-flight (ToF) sensor. The load-handling system and / or the at least one load have one or more retroreflective markings that reflect light emitted by the at least one ToF sensor at least partially back onto the at least one ToF sensor. Furthermore, the method involves processing and evaluating the at least one point cloud to determine whether the at least one load is being handled correctly by the load-handling system.The present invention further relates to a crane comprising a system for checking and / or monitoring a load handling system of the crane comprising several components and designed for handling at least one load.

[0002] With cranes equipped with a load handling system, it is difficult to check the load handling / load release or any misalignment of the load handling system, because - due to the flexibility of the ropes and the degrees of freedom of the mechanical joints, the exact position and orientation of the crane hook cannot be reliably derived from the crane control system or the mechanical structure of the crane. - the load to be picked up by the crane may be in a position / position that cannot be ideally approached by the crane's load-handling device, - at least one hook is not visible to the crane operator.

[0003] Reasons for an unknown position and location of the crane hook are: - Load oscillation of the cable-guided load beam. Since the cable suspension does not represent an ideal load pendulum, the load oscillation cannot be calculated, but only observed or measured. - rope deformed by moment or force stress (flexible rope), - spontaneously occurring jams in the joints of the load-bearing device (e.g. between the hook fork and the crane hook).

[0004] Reasons for an unclear position / location of the load (e.g., a casting ladle) lie in - the condition of the hall floor, - harsh environmental conditions (slag, contamination on the receiving device), - the introduction of random force impulses by the crane during the picking up / dropping off of the object (e.g. diagonal pull when unhooking), - the delivery principle by other means of transport.

[0005] In the worst-case scenario, the aforementioned difficulties could lead to a load falling, which, for example, in the case of a ladle filled with liquid steel at a temperature of approximately 1600 °C, as used in process cranes in a steel mill, would result in immense damage. The load handling system, including the handling of the load and, in particular, the processes of load picking, transport, and / or unloading, must therefore be carefully controlled and monitored.

[0006] AT 192 857 B describes a method for monitoring the load-bearing capacity of a hook using a pressure sensor. However, this arrangement also reduces the available space for the hook and must be very robust, as the main force flows through this sensor.

[0007] German patent DE 10 304 951 A1 describes a method and device for detecting incorrect loads, preferably for casting or charging cranes, in which the weight forces on the trolley of the bridge crane are measured. This allows the load suspension to be detected. However, it cannot detect whether the pan is resting on the hook tip, as the weight is the same in this case.

[0008] EP 1979 259 B1 integrates a piezoelectric element into the crane hook's receiving cup. This element is stressed by the weight of a load carried by the hook via the pin held in the hook's jaw. With this system, correct engagement is only detected during the lifting process. Additionally, the receiving cup's cross-section is slightly reduced.

[0009] With known systems installed in the jaw area, there is generally a risk of damage or impaired function due to contamination or heat exposure. DE 10 2013 017 803 B4 therefore detects misalignment during load handling by measuring the magnetic flux passing through both hooks with a magnetic flux measuring device. The proposed concept is more robust than known concepts because no electronic components need to be integrated into the holding hook. Proximity sensors must also be integrated to determine the correct position of the retaining pins.

[0010] DE 10 2012 015 095 A1 relates to a crane hook with at least one angle measuring unit, which determines a deflection of the hook's center of gravity from a target position, preferably the vertical direction, and to a method for detecting incorrect loads on a crane, preferably a steelworks crane, in which an angle measuring unit determines a deflection of the hook's center of gravity from a target position, preferably the vertical direction, and the measured values ​​are processed and prepared in an evaluation unit. For example, if a ladle suspension pin is correctly inserted into the hook, a specific angle results when lifting due to the position of the center of gravity. An asymmetrical load on the hook causes the hook's center of gravity to move away from the vertical direction. To measure the deflection of the hook from the target position, the vertical axis of the hook is defined by the pivot point and the hook's center of gravity.The deflection of the hook's vertical axis from the plumb line can be caused by a bushing used to suspend the hook. With freely suspended hooks, the vertical axis is generally perpendicular, because, according to the physical laws of gravity and torque, the center of gravity of a freely suspended hook lies directly below the hook's suspension point when unloaded. When comparing the positions of two hooks in a load-bearing device, the difference in the measurement signals indicates that the pan was gripped differently by the hooks.

[0011] WO 2022 / 162066 A1 relates to a lifting device with a lifting rope on which a load-handling device for receiving and lifting a load is provided, and a determining device for determining slack in the lifting rope, wherein said determining device has an inclination sensor for detecting an inclination and / or a tipping velocity and / or a tipping acceleration of the load-handling device and provides a slack signal when the detected inclination and / or tipping velocity and / or tipping acceleration of the load-handling device exceeds a predetermined limit value.

[0012] German patent DE 102 51 910 A1 proposes a container crane that has several optical detection devices arranged on the trolley for detecting the longitudinal and transverse edges of the head block or spreader, as well as the transport device. Additionally, a processing unit associated with the detection devices is provided for determining the spatial position of the edges, the head block or spreader, and the transport device. The processing unit is also configured to determine the position of the longitudinal and transverse centerlines of the head block or spreader and the transport device, their spatial relationship to each other, any possible offsets of the centerlines of the head block or spreader relative to those of the transport device in the longitudinal and transverse directions, and any rotation angle of the centerlines. Any detected offset or rotation angle is compensated for by a positional shift of the spreader relative to the head block.

[0013] Furthermore, DE 10 2021 130 785 A1 describes a crane with a crane boom from which a lifting cable connected to a load-handling device extends, load position sensors for detecting the position of the load-handling device and any load attached to it, environmental sensors for detecting environmental data to determine an environmental model, and a crane control system for controlling lifting cable and crane movements depending on the detected position of the load-handling device and the load attached to it, as well as the determined environmental model. The environmental sensors include imaging sensors for providing three-dimensional real-time environmental data and a georeferencing device for georeferencing the 3D real-time environmental data and determining a georeferenced 3D environmental model.

[0014] Furthermore, DE 10 2020 104 049 A1 discloses a method for controlling agricultural machinery, wherein several optical sensors record the gripper's surroundings from different directions and a control system controls the gripper's position. To achieve reliable gripper control, the control system photogrammetrically determines the gripper's surroundings based on sensor data, and the gripper is then controlled according to this determined topography.

[0015] Additionally, JP 2022-61911A is directed towards a crane monitoring device that monitors a bridge crane and a person working on the bridge crane. Time-of-flight (ToF) cameras are used to generate point groups that represent the shape of the surface of the suspended load and the person, so that the suspended load and the person can be easily identified based on the three-dimensional point group data.

[0016] Based on this, the object of the present invention was to provide a method for checking and / or monitoring a load handling system of a crane comprising several components and designed for handling at least one load, with which it can be determined quickly and reliably whether the at least one load is handled correctly by the load handling system.

[0017] This problem is solved with respect to a method having the features of claim 1 and with respect to a crane having the features of claim 10. The respective dependent claims represent advantageous further developments.

[0018] According to the invention, a method for checking and / or monitoring a load handling system of a crane comprising several components and designed for handling (e.g., for picking up, transporting, and / or delivering) at least one load is provided, in which a) using at least one ToF sensor (time-of-flight sensor), at least one (three-dimensional) point cloud of a work area is generated in which the load handling system is at least partially located, wherein the load handling system has one or more (located in the work area) retroreflective markings which (each) reflect light emanating from the at least one ToF sensor at least partially back onto the (respective) at least one ToF sensor, b) processing of at least one (three-dimensional) point cloud takes place, and c) an evaluation (of at least one product or result obtained by processing the point cloud) is carried out, in which it is derived whether the at least one load is handled correctly by the load-bearing system.

[0019] In step a), at least one point cloud of a work area is first generated in which the load handling system is at least partially, preferably completely, arranged, using at least one ToF sensor (time-of-flight sensor). For example, at least one LiDAR sensor (light detection and ranging sensor) can be used as the at least one ToF sensor. The at least one ToF sensor can also be referred to as at least one ToF camera.

[0020] Time-of-flight (ToF) sensors are 3D camera systems that measure distances using the time-of-flight method. The scene is illuminated with a light pulse, and the camera measures the time it takes for the light to travel to the object and back for each pixel. This time is directly proportional to the distance. The camera thus provides the distance to the object depicted at each pixel. In this way, a point cloud of the area scanned by the ToF sensor can be obtained. Spatial points scanned by a ToF sensor can be described by their position and an intensity-reflectivity value.

[0021] A (three-dimensional) point cloud can be understood as a set of points in a vector space that exhibits an unorganized spatial structure ("cloud"). A point cloud is described by the points it contains, each defined by its spatial coordinates. Additional attributes, such as geometric normals, color values, acquisition time, or measurement accuracy, can also be recorded for each point.

[0022] The at least one ToF sensor may preferably include at least one illumination unit, e.g., an LED and / or a laser diode; at least one optic; at least one (image) sensor that measures the time of flight for each pixel separately; at least one control electronics; and / or at least one unit for calculating the distance from the measured values.

[0023] If the at least one ToF sensor comprises multiple ToF sensors, each of these sensors can generate a (three-dimensional) point cloud. These point clouds can be visualized and superimposed. Furthermore, the (three-dimensional) point clouds can be merged into a single (three-dimensional) point cloud.

[0024] According to the invention, it shows / show - the load handling system (i.e., at least one of the several components of the load handling system), and / or - which at least one load One or more retroreflective markings are present, each reflecting at least some of the light emitted by the at least one ToF sensor back onto the respective ToF sensor. A retroreflective marking is understood to be an element that functions as a retroreflector or that has at least one retroreflective surface that acts as a retroreflector. A retroreflector is an element or surface that reflects radiation (e.g., light) back to its source with minimal scattering. This works over a wide range of angles of incidence, unlike a planar mirror, which only does so when the mirror is exactly perpendicular to the wavefront, i.e., has a zero angle of incidence. The reflection from a retroreflector is therefore brighter than that from a diffuse reflector.In other words, a retroreflector has a higher reflectance than a 100% reflective Lambertian surface. A corresponding definition of a retroreflector can also be found, for example, in the standard DIN SAE SPEC 91471:2023-05. Due to their retroreflective properties, the areas with the retroreflective marker(s) in the generated point cloud differ significantly from the remaining areas of the workspace or environment.

[0025] Reflectivity is a derived value from the intensity of the laser beam and can be calculated using the formula: Reflectivity = Intensity / Sensor Distance 2The reflectivity value is independent of distance because it is multiplied by the square of the distance. Therefore, distance does not need to be considered in the point cloud when searching for areas (points) with high reflectivity. Retroreflective markers can be located, in particular, at joints or joint points where multiple components of the load-bearing system connect. This results in high reflectivity values ​​for these locations in the ToF scan. The reflectivity value is provided along with the point coordinate. The factor can be used, for example, to adjust the obtained value to a specific range or to compensate for sensor-internal effects.

[0026] The retroreflective marking(s) can be, for example, one or more two-dimensional (planar) markings or plates, each with at least one retroreflective surface. Alternatively, the retroreflective marking(s) can also be one or more three-dimensional markings.

[0027] Preferably, at least two, more preferably at least three, and particularly preferably at least four, of the several components of the load-handling system are arranged in the working area. For example, at least the load-handling device(s), the fastening device(s) for the load-handling device(s), and the crossbeam are arranged in the working area. Most preferably, the trolley is at least partially arranged in the working area, and all other components of the load-handling system are completely arranged in the working area.

[0028] In step b), the at least one (three-dimensional) point cloud is processed. This processing can yield at least one product or result (from processing the at least one point cloud), e.g., at least one visualized point cloud and / or at least one (visualized) digital twin. Furthermore, in step b), the at least one (three-dimensional) point cloud is processed, and based on this point cloud, at least one digital twin of at least one part of the load-bearing system and, optionally, of the at least one load, is generated (and visualized). Step b), or the processing, can be performed using at least one processing unit, e.g., at least one computing unit. In other words, the at least one digital twin can be generated (and visualized) using at least one computing unit.Preferably, the processing is carried out automatically (by a processing unit, e.g., a computing unit). In other words, the at least one digital twin can preferably be automatically generated (and visualized) (by a processing unit, e.g., a computing unit).

[0029] In step c), an evaluation is performed (of at least one product or result obtained from processing the point cloud) to determine whether the at least one load is handled correctly by the load-handling system, i.e., whether there is any misalignment of the load-handling system or of the at least one load relative to the load-handling system that could, for example, cause the at least one load to fall from the load-handling system. Preferably, the evaluation in step c) can determine whether the at least one load is correctly picked up, transported, released, and / or held by the load-handling system. In particular, the evaluation in step c) can determine whether the at least one load is correctly picked up (or held) by the load-handling system.In step c), the at least one (visualized) digital twin (obtained in step b) is evaluated to determine whether the at least one load is being handled correctly by the load handling system. This evaluation can be performed manually, for example, by a person, such as the crane operator. This person can view the product or result obtained from processing the point cloud—i.e., the at least one visualized point cloud and / or the at least one (visualized) digital twin—displayed on a screen and determine from this view whether the at least one load is being handled correctly by the load handling system. Alternatively or additionally, the evaluation can also be performed using at least one evaluation unit, such as at least one computing unit. For example, the evaluation can be performed automatically (by a processing unit, such as a computing unit).The evaluation can preferably be performed manually (i.e., by a human) and / or automatically. For example, the entire step c) or steps b) and c) (and thus the entire procedure) can also be carried out autonomously by a computer system.

[0030] In step c), a process analysis system can preferably be used for the evaluation. This process analysis system can be used if a person performs the evaluation and / or if an evaluation device, e.g., a computing unit, performs the evaluation. For example, the evaluation in step c) can be carried out by a person, e.g., the crane operator, using at least one evaluation unit, e.g., a computing unit, where the at least one evaluation unit comprises a process analysis system.

[0031] The process analysis system can rule-based check the movement speeds, maximum / minimum distances, and / or inclination angles between components for each parameter set and classify the results regarding the proper functioning of the handling process for the load handling system. Furthermore, stored parameter sets for the correct relative positions of components of a load handling system, according to mechanical equilibrium, can also be used for process analysis. For example, a jammed hook that no longer realigns itself can be detected. The positions and orientations of two crane hooks encompassed by the load handling system can be analyzed relative to each other to ensure the parallelism of the hook movement during lifting or unloading.The motion data of the load-handling system components can be interpreted over time to identify and assess their speed and dynamics. For example, typical motion characteristics can be identified from displacement / time diagrams for the individual components of the load-handling system, and abnormalities, such as oscillation of the crossbeam, can be investigated. This allows for a warning to be issued if a dangerous equilibrium situation develops. Many such tests can be performed redundantly to increase the reliability of the results and to make the regulatory framework increasingly safer in terms of the functional safety of a work system. For example, tests can be carried out according to one, several, or all of the following rules: - If the position of the hook mouth center and the pin center of the casting ladle coincide within a certain tolerance range of, for example, < 100 mm, the pin is securely in the hook mouth. - When picking up or dropping off the ladle, the hook tip must be guided safely below the pin, because otherwise the ladle may be turned or pulled into an unclear position upon contact with a crane hook, or in extreme cases, tip over. - If the hook tip of the crane hook lifts the pin of the ladle, thus bringing the component group into an unstable equilibrium, in extreme cases the pin slips outwards from the crane hook tip and the ladle tips over.

[0032] In steps b) and c), for example, at least one digital twin of at least one part (or the part arranged in the work area) of the load-handling system (e.g., of at least two or at least three of the several components of the load-handling system), preferably of the (entire) load-handling system, and optionally of the at least one load, can be generated based on the at least one point cloud. From this digital twin, it can be deduced whether the at least one load is being handled correctly by the load-handling system. Here, based on the at least one digital twin, an equilibrium position of at least two of the several components, preferably of the (or all) components, of the load-handling system can first be determined. From this determined equilibrium position, it can then be deduced whether the at least one load is being handled correctly by the load-handling system.The digital twin describes the position and orientation of at least one part (of the multiple components) of the load-bearing system. The generated twin thus also represents the equilibrium position. Therefore, it is possible to directly verify from the shape of the (visualized) digital twin whether the load is being handled correctly by the load-bearing system, in particular whether it is being lifted (or held). The use of one or more retroreflective markers simplifies and accelerates the generation of the digital twin, thereby also improving its accuracy.

[0033] Alternatively or additionally, in steps b) and c), for example, the at least one point cloud can also be visualized, whereby it can then be deduced from the at least one visualized point cloud whether the at least one load is handled correctly by the load-bearing system, in particular whether it is being absorbed (or held). This is possible in particular through the use of retroreflective markings. For example, the equilibrium position of at least two of the several components, preferably of the (or all) components, of the load-bearing system can also be determined by the retroreflective markings visible in the visualized point cloud, and it can be deduced from the determined equilibrium position whether the at least one load is being handled correctly by the load-bearing system. Alternatively, for example, based on the at least one visualized point cloud, it can be checked or...It will be determined whether the multiple retroreflective markings are arranged together in a predefined pattern from one or more viewing directions, and from this it will be deduced whether the at least one load is handled correctly by the load-bearing system.

[0034] Furthermore, steps b) and c) can also be performed in such a way that neither a visualization of the at least one point cloud is carried out nor a digital twin is generated based on the at least one point cloud. In this way, a suitably configured computing unit can also calculate or derive, using an alternative processing and evaluation method, whether the at least one load is being handled correctly by the load-bearing system. Steps b) and c) can be performed autonomously by a computer system, for example, by at least one ASIL-certified LiDAR sensor. Consequently, the entire procedure can also be performed autonomously by a computer system, for example, by at least one ASIL-certified LiDAR sensor.

[0035] By using at least one time-of-flight (ToF) sensor in combination with one or more retroreflective markers on at least one of the several components of the load-handling system and / or on the load itself, it is possible to quickly and reliably determine whether the load is being handled correctly by the system. The ToF sensor can generate a point cloud of the working area contactlessly and with minimal time expenditure. This point cloud contains information about the precise relative positions of the load-handling system and the load. After processing, this data can be analyzed to determine whether the load is being handled correctly by the system. Because the measurement is contactless, the sensors do not interfere with or obstruct the load-handling system.In particular, measuring systems attached to the load-bearing system can be dispensed with.

[0036] The use of one or more retroreflective markers significantly increases the speed and accuracy of processing and evaluation, and thus the overall process. For example, if a digital twin of the load-bearing system and / or the load is generated during processing, this generation can be simplified and accelerated by the one or more retroreflective markers, thereby also improving the accuracy of the digital twin's creation. The retroreflective marker(s) can be used as "landmarks" for the safe and precise positioning of bodies and / or joints. Conversely, the use of retroreflective markers can even eliminate the need to generate a digital twin altogether, further increasing the speed of the method without compromising accuracy.Ultimately, this method exploits the fact that the retroreflective markers—due to their higher reflectance values ​​compared to the surroundings—stand out clearly in the point cloud generated by the at least one ToF sensor (and annotated with reflectance values) and are thus easily distinguishable from the surroundings. In this way, specific marked areas can be assigned very easily and quickly, and the position of individual markers and multiple markers relative to each other can be determined very quickly and easily without needing to know the location of the areas marked by the markers beforehand. The retroreflective marker(s) thus improve the method, particularly in terms of robustness, speed, and reliability.

[0037] The visualized point cloud can be annotated in various ways (using different colors), for example, by distance (between the ToF sensor and each point in the point cloud) or by reflectance values ​​(of the points in the point cloud). A point cloud annotated with reflectance values ​​makes it particularly easy to identify the retroreflective markers when viewing the visualized point cloud.

[0038] In the method according to the invention, the verification and / or monitoring, or the detection, of whether the at least one load is handled correctly by the load-handling system can be carried out solely on the basis of knowledge of the positions of components of the load-handling system (or specific parts thereof, such as joints) and optionally additionally of the load itself, which are determined contactlessly by means of at least one ToF scan. Knowledge of the body orientation (x-rotation, y-rotation, z-rotation) of the crane components is not necessary. Therefore, no angle measuring system is required.

[0039] The position and orientation of the load do not need to be determined, as it can be clearly deduced whether the at least one load is being handled correctly by the load-handling system even without considering the load itself. For example, a misalignment can be clearly identified from the equilibrium position of the load-handling system and / or from the position of the retroreflective markings, or it can be deduced whether the at least one load is being handled correctly by the load-handling system. However, to further increase the accuracy of the method, the at least one load can optionally be included in the measurement.

[0040] Preferably, by combining contour detection and the detection of retroreflective markers, position determination can be performed even more reliably and with even shorter latency. The retroreflective markers can be used, for example, to parameterize a 3D geometry model of the object used in the ongoing process, ensuring optimal geometry fitting for aligning the 3D model with the point cloud. In this case, the object type (e.g., a casting ladle) of the partial point cloud is known. This approach is particularly useful when the object is partially obscured and only an incomplete point cloud is available, or when the dimensional variant of the object type (e.g., a casting ladle) is unknown. To determine the exact shape of the 3D model, different model variations can be generated by varying the parameters and checked for the best possible match with the point cloud.The best shape can then be used for the further process. This variant can be used in particular when the point cloud of the body is complete in the essential zones.

[0041] The crane can be any type of crane with a load-handling system. Preferably, the crane is a process crane, such as those used in the steel industry.

[0042] The at least one load can be any load that can be handled and / or lifted by the load handling system. Preferably, the at least one load is a ladle, such as those used in the steel industry. The process crane can preferably be selected from the group consisting of casting cranes, charging cranes, ladle transport cranes, slab transport / slab turning cranes, coil and bundle transport cranes, gripper cranes, forging cranes, magnetic spreader cranes, automatic cranes, and combinations thereof.

[0043] The load handling system is preferably a cable-guided load handling system.

[0044] The method according to the invention is preferably a method for checking and / or monitoring a load handling system of a process crane (in the steel industry) comprising several components for handling (e.g. for receiving, transporting and / or discharging) at least one load, wherein the at least load is preferably at least one ladle, e.g. for transporting liquid metals and / or alloys.

[0045] The inventive method for checking and / or monitoring a load handling system of a crane comprising several components and designed for handling at least one load can preferably also be a method for detecting the correct handling of at least one load by a load handling system of a crane comprising several components.

[0046] The method according to the invention can be used, for example, to check the load handling system by performing steps a) and b) once each at a specific time or several specific times (e.g., during the load handling process and / or the load release process), so that a three-dimensional point cloud is generated for the specific time(s) and thus it can be checked for the specific time(s) whether the at least one load is handled correctly by the load handling system, in particular whether it is picked up or held (or whether, instead, there is a misalignment with respect to the load handling system or the relative position of the load to the load handling system).

[0047] The method according to the invention can, for example, also be used to monitor the load handling system by repeatedly performing steps a) and b), preferably steps a) to c), over a specific period of time – e.g., during the (entire) load handling process and / or the load release process. For example, steps a) and b), preferably steps a) to c), can be performed at least once per second, preferably at least twice per second, particularly preferably at least five times per second, and most preferably at least ten times per second.As a result, one or more images per second, and thus a kind of video, can be obtained with which the position of the load handling system can be continuously monitored, so that the load handling process and / or load release process can be continuously monitored and it can be accurately determined whether and when the at least one load is being handled correctly by the load handling system.

[0048] A preferred embodiment of the method according to the invention is characterized in that the one or more retroreflective markings - each containing or consisting of at least one (reflective) primer and retroreflective glass beads, and optionally at least one clear coat protective sealant, wherein the retroreflective glass beads preferably have a mean diameter in the range of 0.1 mm to 0.3 mm, and / or - each formed in a planar (or flat) form, preferably each rectangular form, and / or, - each have a length and / or width of at least 150 mm, preferably at least 200 mm, and / or - each have a size and / or shape that correlates with a scanning pattern of the at least one ToF sensor, and / or - the one or more retroreflective markings each have a retroreflective surface arranged at an angle of 30° to 60°, preferably 40° to 50°, particularly preferably 44° to 46°, to a main direction of movement of the crane, and / or - have a reflectance value (determined according to the manual “LiDAR sensor Livox Horizon”, 2019) in the range of 151 to 255, preferably in the range of 160 to 255, particularly preferably in the range of 180 to 255, most preferably in the range of 200 to 250.

[0049] According to the manual “LiDAR sensor Livox Horizon”, 2019, the reflectance value of an object can in principle be in the range of 0 to 255, where the range 0 to 150 corresponds to the reflectance of objects in the range of 0 to 100 % in the Lambertian reflection model and the range 151 to 255 corresponds to the reflectance of objects with retroreflection properties.

[0050] The at least one (reflective) primer preferably contains or consists of at least one component selected from the group consisting of xylene isomers, hydrocarbons, preferably C6-C7 hydrocarbons, isoalkanes, cycles, n-hexane, and mixtures thereof. The at least one clear coat protective sealant preferably contains or consists of at least one component selected from the group consisting of acetone, 2-methoxy-1-methylethyl acetate, butan-1-ol, n-butyl acetate, and mixtures thereof. The clear coat protective sealant protects the retroreflective glass beads from external influences and simultaneously ensures the adhesion of the retroreflective glass beads to the primer. All materials of the retroreflective marking(s) are preferably suitable for high temperature loads, e.g., for temperatures above 600 °C, preferably above 800 °C.

[0051] The mean diameter of the retroreflective glass beads can be determined, for example, according to ISO 13320:2020-01.

[0052] The retroreflective glass beads - preferably contain or consist of soda-lime glass, and / or - preferably have a refractive index in the range of 1.6 to 2.2, and / or - preferably have a retroreflection value of at least 500 mcd / m 2 ·Ix, preferably of at least 1000 mcd / m² 2 ·Ix, particularly preferably of at least 1500 mcd / m² 2 ·Ix, on.

[0053] The refractive index can be determined, for example, according to DIN EN 1423:2013-03.

[0054] The retroreflection value can be determined, for example, according to DIN EN 1436: 2018-03.

[0055] The one or more retroreflective markings can each have at least one retroreflective (surface) surface.

[0056] The size and shape of the retroreflective marker(s) can be defined depending on the task, and / or can correlate with the scanning pattern of the ToF scanner or LiDAR scanner, and / or can influence the detection latency.

[0057] The load-bearing system and / or the at least one load has / have at least one retroreflective marking that reflects at least some of the light emitted by the at least one ToF sensor back onto the at least one ToF sensor. Preferably, the load-bearing system and / or the at least one load has / have at least two, more preferably at least three, and most preferably at least five, retroreflective markings that (each) reflect at least some of the light emitted by the at least one ToF sensor back onto the (respective) at least one ToF sensor.

[0058] Another preferred embodiment of the method according to the invention is characterized in that - the multiple components of the load-bearing system each have at least one, preferably at least two, particularly preferably at least three, and most preferably at least five, of the retroreflective markings, and / or - the multiple components of the load-bearing system (or the load-bearing system) have a total of at least two, preferably at least three, particularly preferably at least five, and most preferably at least ten, retroreflective markings, and / or - each of the loads has at least one, preferably at least two, particularly preferably at least three, and most preferably at least five retroreflective markings.

[0059] For three-dimensional positioning and orientation, three (or more) retroreflective markings can preferably be used. However, based on prior knowledge of the relative positions of the components (e.g., a hook hanging over a joint below a crossbeam), only one or two retroreflective markings can also be used.

[0060] Another preferred embodiment of the method according to the invention is characterized in that the at least one ToF sensor - is attached to the crane, and / or - includes at least two, preferably at least four, ToF sensors, and / or - comprising at least one LiDAR sensor (light detection and ranging sensor), preferably at least two LiDAR sensors, particularly preferably at least four LiDAR sensors, wherein the at least one LiDAR sensor is preferably at least one ASIL-certified (Automotive Safety Integrity Level-certified) LiDAR sensor, particularly preferably at least one ASIL-certified LiDAR with embedded intelligence, - comprising at least one ToF sensor with a limited field of view, preferably at least one LiDAR sensor with a limited field of view, or is at least one ToF sensor with a limited field of view, preferably at least one LiDAR sensor with a limited field of view, wherein the limited field of view is defined by two angles comprising a vertical angle and a horizontal angle, wherein one of the two angles is at most 120° and the other of the two angles is at most 30°, wherein the vertical angle is particularly preferably at most 120° and / or the horizontal angle is at most 30°.

[0061] By attaching at least one ToF sensor to the crane, there is no relative movement between the sensor system and the crane, thus simplifying assembly, calibration, measurement and evaluation.

[0062] Using at least one ToF sensor with a limited field of view increases the proportion of points that can be assigned to the work area when generating the point cloud.

[0063] The at least one ASIL-certified LiDAR sensor preferably comprises at least two, particularly preferably at least four, ASIL-certified LiDAR sensors.

[0064] The at least one ASIL-certified LiDAR sensor with embedded intelligence preferably comprises at least two, particularly preferably at least four, ASIL-certified LiDAR sensors with embedded intelligence.

[0065] The at least one LiDAR sensor can be at least one pulsed LiDAR sensor. This can increase the measurement accuracy.

[0066] The at least one LiDAR sensor with a limited field of view preferably comprises at least two, particularly preferably at least four, LiDAR sensors with a limited field of view.

[0067] The at least one LiDAR sensor may preferably include at least one illumination unit, e.g., an LED and / or a laser diode; at least one optic; at least one (image) sensor that measures the time of flight for each pixel separately; at least one control electronics unit; and / or at least one unit for calculating the distance from the measured values.

[0068] LiDAR sensors such as those that can be used in the present invention are defined and described, for example, in DIN SAE SPEC 91471:2023-05.

[0069] A LiDAR-based measurement system and method, comprising one or more LiDAR sensors, generates a consistent, three-dimensional, time-dependent point cloud of high measurement quality, enabling robust, fast, and reliable determination of the position and orientation of bodies, joints, and retroreflective markings in the work area. The at least one LiDAR sensor is preferably an ASIL-certified (Automotive Safety Integrity Level certified) LiDAR sensor, particularly preferably with embedded intelligence.In this case, it is particularly preferred that the at least one LiDAR sensor includes at least one processing unit configured to process the at least one point cloud, visualizing it and / or generating at least one digital twin of at least one part of the load-bearing system and, optionally, the at least one load. Furthermore, the at least one processing unit is configured to evaluate the at least one visualized point cloud (annotated with reflectance values) and / or the at least one digital twin to determine whether the load is being handled correctly by the load-bearing system. The entire process can thus be performed autonomously by the at least one ASIL-certified LiDAR sensor.

[0070] Preferably, the at least one ToF sensor comprises several ToF sensors with overlapping, preferably identical, viewing areas. By using multiple ToF sensors with overlapping, preferably identical, viewing areas, redundancy in the data can be achieved, thus increasing the reliability of the results for an automated solution.

[0071] Another preferred embodiment of the method according to the invention is characterized in that the several components of the load-bearing system - include at least one rope, and / or - include a truss, and / or - include a trolley, and / or - comprise at least one, preferably at least two, load-handling devices, wherein the at least one load-handling device is preferably at least one crane hook, particularly preferably at least two crane hooks, and / or - comprising at least one, preferably at least two fastening means, for at least one (or for the at least one) load-bearing device, wherein the at least one fastening means is preferably at least one hook fork, preferably at least two hook forks.

[0072] For example, the traverse can be attached to the trolley via at least one rope and / or the at least one load-bearing device can be attached to the traverse via at least one fastening device.

[0073] Particularly preferably, the several components of the load-bearing system comprise a crossbeam, wherein the crossbeam has one or more retroreflective markings (or the one retroreflective marking or one or more of the retroreflective markings).

[0074] The multiple components particularly preferably comprise a trolley, at least one rope, a crossbeam, at least two load-handling devices, preferably at least two crane hooks, and at least two attachment points for the load-handling devices, preferably at least two hook forks. It is preferred that the crossbeam has one or more retroreflective markings (or the single retroreflective marking or one or more of the retroreflective markings). For example, the crossbeam can be attached to the trolley via the at least one rope, preferably via several ropes, and / or the at least two load-handling devices can be attached to the crossbeam via the at least two attachment points.

[0075] Crane and load components can preferably be designed so that they assume different center of gravity positions and orientations in the unloaded / loaded state.

[0076] Preferably, at least one load-handling device, one fastening device, and the crossbeam are arranged within the working area. Most preferably, the trolley is at least partially arranged within the working area, and all other components of the load-handling system are completely arranged within the working area.

[0077] If, in step b) (ua), at least one digital twin of at least one part of the load-handling device is created, then the at least one part of the load-handling system preferably comprises at least the at least one load-handling device, the at least one fastening device, and the crossbeam. Most preferably, the at least one part of the load-handling system comprises at least one part of the trolley and all other components of the load-handling system.

[0078] Another preferred embodiment of the method according to the invention is characterized in that in the processing of the at least one point cloud in step b), the at least one point cloud is visualized and / or based on the at least one point cloud, at least one digital twin of at least one part of the load handling system (or of the part of the load handling system arranged in the work area or of a part of the part of the load handling system arranged in the work area) and / or of the at least one load is generated, and In step c) the evaluation involves an evaluation of at least one visualized point cloud and / or at least one digital twin, from which it is derived whether the at least one load is handled correctly by the load-bearing system.

[0079] In step b), the at least one (three-dimensional) point cloud is preferably processed, whereby the at least one point cloud is visualized and / or, based on the at least one (three-dimensional) point cloud, at least one digital twin of at least one part (e.g., of at least one or at least two of the several components) of the load-handling system (preferably of the entire load-handling system) and optionally of the at least one load is generated (and visualized). The at least one part of the load-handling system preferably comprises at least one load-handling device, at least one fastening device, and the crossbeam. Most preferably, the at least one part of the load-handling system comprises at least one part of the trolley and all other components of the load-handling system.

[0080] In step c), an evaluation of the at least one visualized point cloud and / or the at least one (visualized) digital twin is preferably performed to determine whether the at least one load is being handled correctly by the load handling system, i.e., whether there is any misalignment of the load handling system or of the at least one load relative to the load handling system that could, for example, cause the at least one load to fall from the load handling system. Preferably, it can be determined whether the at least one load is being correctly picked up, transported, or released by the load handling system. In particular, it can be determined whether the at least one load is being correctly picked up or held by the load handling system.

[0081] In steps b) and c), preferably based on the at least one point cloud, at least one digital twin of at least one part of the load-bearing system (e.g., of at least two of the several components of the load-bearing system), preferably of the (entire) load-bearing system, and / or of the at least one load can be generated (and visualized), and from the at least one (visualized) digital twin, it can be derived whether the at least one load is handled correctly by the load-bearing system. Here, based on the at least one (visualized) digital twin, an equilibrium position of at least two of the several components, preferably of the (or all) components, of the load-bearing system can first be determined, and from the equilibrium position thus determined, it can be derived whether the at least one load is handled correctly by the load-bearing system.The digital twin describes the position and orientation of at least one part (of the multiple components) of the load-bearing system. Thus, the generated twin also represents the equilibrium position. Therefore, it is possible to directly verify from the shape of the digital twin whether the load (at least one component) is being handled correctly by the load-bearing system.

[0082] Alternatively or additionally, in steps b) and c), the at least one point cloud can be visualized, and it can then be deduced from the at least one visualized point cloud whether the at least one load is being handled correctly by the load-bearing system. This is particularly possible through the use of retroreflective markings. For example, the equilibrium position of at least two of the several components, preferably all components, of the load-bearing system can be determined using the retroreflective markings visible in the visualized point cloud, and it can be deduced from the determined equilibrium position whether the at least one load is being handled correctly by the load-bearing system. Alternatively, for example, based on the at least one visualized point cloud, it can be checked or...It will be determined whether the multiple retroreflective markings are arranged together in a predefined pattern from one or more viewing directions, and from this it will be deduced whether the at least one load is handled correctly by the load-bearing system.

[0083] In particular, steps b) and c) can involve visualizing at least one point cloud and, based on this point cloud, generating (and visualizing) at least one digital twin of at least one part of the load-bearing system and, optionally, of the load itself. This evaluation then determines whether the load-bearing system is handling the load correctly. Ultimately, both the point cloud and the digital twin can be evaluated and used to verify and / or monitor whether the load-bearing system is handling the load correctly.

[0084] For example, at least one visualized point cloud and / or at least one visualized digital twin can be displayed on a screen (of an assistance system). The crane operator can then use the screen display to determine whether the load is being handled correctly by the load handling system. The visualized digital twin and the visualized point cloud can also be overlaid on the display of the assistance system, allowing for easy verification of the assistance system's accuracy.

[0085] A digital twin is generally understood to be a virtual representation or digital representation of a tangible or intangible object from the real world in the digital world. The at least one generated digital twin is ultimately a (visually representable) computed model of (at least a part of) the load-bearing system or (at least a part of) the multiple components of the load-bearing system. The at least one digital twin can be visualized within step b).

[0086] A kinematic system is in equilibrium when a balance of moments and forces is achieved. A cable-guided crane's load-handling system assumes a stable geometric form when only tensile forces are acting, since the chain of rigid bodies (crossbeam, hook fork, crane hook, load) and flexible cables is not dimensionally stable. The equilibrium of a cable-guided load-handling system is determined by its own weight. A suspended load alters the equilibrium position of the system and can cause changes in the position and orientation of the rigid bodies or the joints between them. These changes in position and orientation can be further induced by specially shaped components.An incorrectly attached load also causes a change in the equilibrium position, and thus in the position and orientation of the rigid bodies and joints of this kinematic chain. By non-contactly capturing the position of the multiple components (and / or the joint points) of the load-bearing system, the equilibrium position can be clearly identified and analyzed for misalignment, eliminating the need for measuring systems attached to the load-bearing system. The position of bodies or joints of the load-bearing system and / or the load itself can be determined based on (continuous time-of-flight) scans, which generate a point cloud of the work area, and the subsequent creation of a digital twin, e.g., using geometry fitting. Retroreflective markings, preferably at exposed locations (e.g., at the joint points), improve the detection method in terms of robustness, speed, and reliability.

[0087] The current equilibrium position of the load-bearing system can be determined from the position / change in position (x, y, z) of the components / joints. This position / change in position (x, y, z) of the components / joints of the load-bearing system allows for the reliable detection of both correct and incorrect load placement, as well as misalignment within the entire load-bearing system. The physical principle of equilibrium can be used for this purpose, particularly under the specific conditions of flexible systems. Optionally, the load itself can be included in the misalignment detection process.

[0088] Another preferred embodiment of the method according to the invention is characterized in that, in step b), based on the at least one point cloud, at least one digital twin of at least one part of the load-bearing system (e.g., of at least two of the several components of the load-bearing system), preferably of the (entire) load-bearing system and optionally of the at least one load, is generated, and in step c), based on the at least one digital twin, an equilibrium position of at least two of the several components, preferably of the (or all) components, of the load-bearing system is determined, and from the determined equilibrium position, it is derived whether the at least one load is handled correctly by the load-bearing system.

[0089] According to a further preferred embodiment of the method according to the invention, the at least one digital twin is generated using at least one geometry fitting process, in which at least one three-dimensional model of at least one part of the load-bearing system, preferably of the (entire) load-bearing system, is transformed into the at least one point cloud, wherein in the at least one geometry fitting process - at least one shape-based (or contour-based) geometry fitting is performed, in which preferably the at least one three-dimensional model is transformed into the at least one point cloud in such a way that at least a partial geometric (preferably greatest possible) correspondence is achieved between the at least one point cloud and the at least one three-dimensional model, wherein preferably a mean deviation of the points of the at least one three-dimensional model from the points of the point cloud is at most 20 cm, more preferably at most 15 cm, particularly preferably at most 10 cm, and most particularly preferably at most 5 cm, and / or - at least one geometry fitting based on one or more retroreflective markings is performed, in which preferably the at least one three-dimensional model is transformed into the at least one point cloud in such a way that one or more areas of the at least one point cloud, which are characterized by increased reflection caused by the one or more retroreflective markings, are assigned to one or more corresponding areas of the at least one three-dimensional model.

[0090] The at least one geometry fitting process can also be described as at least one registration of a three-dimensional geometry with a point cloud (transformation of the rigid 3D geometry so that the distances between the point cloud and the 3D geometry become as small as possible).

[0091] The geometry fitting process can preferably be contour-based (appearance of the body) and / or based on the retroreflective marking(s). Contour-based or shape-based geometry fitting and geometry fitting based on retroreflective markings can be used as alternative or complementary localization methods. This further reduces latency and increases localization accuracy.

[0092] In the shape-based geometry fitting process, the following approach can be used, for example: Based on prior knowledge (e.g., the truss is suspended by cables), the point cloud can be reduced to the relevant area containing the truss, and an initial estimate of the truss's position can be obtained. This initial estimate will generally not reflect the exact actual position of the truss and can be corrected. For this purpose, a standard procedure (e.g., ICP – "Iterative Closest Point" with the extension of compatible normals) can be used to transform / fit the 3D model of the truss into the point cloud from its initial position. This involves iteratively determining corresponding pairs of points on both objects based on their distance, considering only those pairs whose normal vectors point in similar directions. From these pairs, a rotation and translation are then calculated that minimizes the pairwise distances.Limiting the analysis to pairs with similar normals prevents the registration of sensor-facing sides of the model, which cannot be represented in the point cloud, and thus stabilizes the geometry fitting process. A similar approach is used for hook detection. Here, too, prior knowledge (hooks are located in two areas under the crossbeam) allows the point cloud to be reduced accordingly, and an initial estimate of the hook positions to be derived. This estimate can then be improved using geometry fitting (e.g., ICP with compatible normals). However, only the lower part of a crane hook is used as the 3D model here, since the upper part is mounted in a hook fork that obstructs the sensor's view of the hook geometry. Load detection (e.g.,The casting ladle also utilizes prior knowledge to reduce the point cloud, since a load ready to be lifted can only be located below the crossbeam and between the crane hooks. If corresponding 3D models of the load are available, these can be used for the subsequent geometry fitting process. In the specific case of a casting ladle, a generic cylindrical model can also be used.

[0093] The geometry fitting process based on retroreflective markers can proceed as follows: Due to their significantly higher reflectivity, the points generated on the markers can be easily extracted from the total number of points. The current position of the markers can then be calculated from these extracted points. The actual positions of the markers on the objects to be detected (e.g., crossbeam, hook, ladle) are known. By mapping the extracted areas to the known markers, the position of the objects in the point cloud can be derived. This detection process can be used as an alternative to the previously described method or as a supplementary analysis to increase the stability of the detection system.

[0094] Another preferred embodiment of the method according to the invention is characterized in that, prior to carrying out the at least one geometry fitting process, - that at least one three-dimensional model is parameterized, preferably by varying parameters that characterize the multiple components of the load-bearing system and / or the at least one load in the three-dimensional model during an initial point cloud acquisition, and then selecting a suitable parameter sequence and using it for the geometry fitting process, and / or - the size of the at least one three-dimensional model is adjusted, preferably with the one or more retroreflective markings being arranged at a predefined distance to at least one edge or at least one surface of the at least one load or one of the several components of the load-bearing system, and the size of the at least one three-dimensional model being adjusted based on a determined position and / or orientation of the one or more retroreflective markings.

[0095] The geometry fitting process can improve the accuracy of position determination.

[0096] The parameters that characterize the multiple components of the load-handling system and / or the at least one load in the three-dimensional model can preferably be the diameters and lengths of the at least one load and / or of one or more of the multiple components of the load-handling system. For example, a ladle is essentially characterized by its overall height, various diameters, and the position of the pins for the hook attachment, which can serve as parameters. The hook attachment is the spatial location for the hook jaw as the counterpart to the pin. A crane hook is defined, for example, by the hook suspension and the position of the hook jaw, which can also serve as parameters.

[0097] In geometry fitting, the three-dimensional model should correspond sufficiently closely to the real object. In reality, the appearance of an object is generally known (e.g., the object type "ladle"). However, the exact dimensions vary, for example, because different sizes of ladles circulate in a foundry, for which no geometric specifications are normally known, and the individual ladle cannot be identified. The different real-world shapes, and thus the variations in the point cloud, mean that the generic three-dimensional model of the object, e.g., the ladle, cannot be fitted exactly. This is because different subsets of the point cloud are used at different times during the execution of the geometry fitting algorithm to fit the generic three-dimensional model.As a result, the three-dimensional model jumps between different positions and orientations depending on the selection made during the fitting routine. This problem can be solved by parameterizing the at least one three-dimensional model and / or adjusting its size before generating the at least one digital twin of the load-bearing system. During parameterization, the dimensional parameters of the ladle model can be varied randomly or according to a rule, positioned using geometry fitting / registration, and evaluated for agreement with the point cloud. The highest agreement means that this dimensional variant is used for the digital twin. When adjusting the size of the at least one three-dimensional model, retroreflective markers can be added to the real object (i.e., the load and / or the component of the load-bearing system), for example.Markers are placed one meter below the top edge and one meter above the bottom edge. These markers are located in the point cloud, and the pan's height can be derived from their position. A parametric pan model can then be taken and converted into a concrete three-dimensional model with the appropriate dimensions (scaled). The resulting three-dimensional model can then be used for geometry fitting as before.

[0098] According to a further preferred embodiment of the inventive method, the load-bearing system and / or the at least one load have several, preferably at least three, particularly preferably at least four, most preferably at least five, of the retroreflective markings, wherein the retroreflective markings are only visible when the at least one load is handled correctly by the load-bearing system (e.g., picked up or...).is held), together from one or more viewing directions (each) in a predefined pattern, preferably in a predefined ASIL-compliant (Automotive Safety Integrity Level-compliant) pattern (according to ISO 26262-1:2018-12), wherein in the evaluation in step c) based on the at least one visualized point cloud it is determined whether the multiple retroreflective markings together from one or more viewing directions are arranged in the predefined pattern, and from this it is derived whether the at least one load is handled correctly by the load-bearing system, wherein preferably - at least two of the several components of the load-bearing system each have at least one of the several retroreflective markings, and / or - in addition, at least one load has one of the several retroreflective markings.

[0099] ASIL stands for Automotive Safety Integrity Levels and is a risk classification system defined within the framework of the standard ISO 26262-1:2018-12.

[0100] In this implementation variant, retroreflective markings can be applied in such a way that, collectively, the retroreflective markings on the at least one load and / or on at least one of the several components of the load-bearing system form a common, typical pattern (e.g., a crosshair or a line between two beams) when the at least one load is handled correctly by the load-bearing system. This common, typical pattern is not formed when the at least one load is not handled correctly by the load-bearing system. Ultimately, it can be directly deduced from the visualized point cloud whether the at least one load is handled correctly by the load-bearing system by directly reading from the visualized point cloud whether the several retroreflective markings are arranged together (from one or more viewing directions) in the predefined pattern.If the correct pattern is recognizable in the visualized point cloud, it can be concluded that at least one load is being handled correctly by the load-bearing system. If the correct pattern is not recognizable in the visualized point cloud, it can be concluded that at least one load is not being handled correctly by the load-bearing system, but rather that there is a misalignment.

[0101] The reflectors can be positioned so that they are recognized as a pattern in one or more desired views, for example, as a target crosshair. The resulting situation can be easily and reliably identified by the crane operator on an assistance screen displaying the visualized point cloud, and is equally suitable for efficient automated analysis. The analysis can be supported, if necessary, by automatically assigned guidelines. The result is a reliable process control method based solely on the output of a point cloud, thus eliminating the need to create a digital twin. Consequently, this is a very fast method with a very simple evaluation process.

[0102] The predefined pattern could be, for example, a line, parallel lines, a cross, a U-shaped pattern, or an H-shaped pattern.

[0103] It can be useful if the viewer wants to analyze a point cloud with retroreflective markers that is not located on the main axis of the sensor alignment. In this case, only a thin line of the retroreflective marker would be visible in the orthogonal main view. Therefore, the retroreflective markers can be designed so that they are equally visible in several selected orthogonal main views. This can be achieved by tilting the retroreflective markers, e.g., by 45° (e.g., with respect to a main direction of crane movement). For example, a retroreflective marker can be illuminated in the direction of travel, but also provides a sufficiently large area for visualization in the crane assistance system in the orthogonal main viewing direction in the direction of travel.

[0104] Preferably, the at least one predefined pattern is at least one predefined ASIL-compliant (Automotive Safety Integrity Level-compliant) pattern (according to ISO 26262-1:2018-12). This could, for example, be a pattern with two parallel lines across several, preferably all, components of the load-bearing system (analogous to a road marking).

[0105] According to a further preferred variant of the method according to the invention, in particular the points of the at least one point cloud lying behind the component or the at least one load from the viewing direction (of an observer) can also be visualized.

[0106] The present invention further relates to a crane comprising a system for checking and / or monitoring a load handling system of the crane comprising several components for handling (e.g. for picking up, transporting, and / or delivering) at least one load, wherein the system further comprises at least one processing unit for processing the at least one point cloud, and wherein the load-bearing system has one or more retroreflective markings which (each) reflect light emanating from the at least one ToF sensor at least partially back onto the (respective) at least one ToF sensor.

[0107] The at least one processing unit can be at least one computing unit or at least one computer that is configured to process the at least one (three-dimensional) point cloud.

[0108] A preferred embodiment of the crane according to the invention is characterized in that the one or more retroreflective markings - each containing or consisting of at least one (reflective) primer and retroreflective glass beads, and optionally at least one clear coat protective sealant, wherein the retroreflective glass beads preferably have a mean diameter in the range of 0.1 mm to 0.3 mm, and / or - each formed in a planar (or flat) form, preferably each rectangular form, and / or, - each have a length and / or width of at least 150 mm, preferably at least 200 mm, and / or - each have a size and / or shape that correlates with a scanning pattern of the at least one ToF sensor, and / or - the one or more retroreflective markings each have a retroreflective surface arranged at an angle of 30° to 60°, preferably 40° to 50°, particularly preferably 44° to 46°, to a main direction of movement of the crane, and / or - have a reflectance value (determined according to the manual “LiDAR sensor Livox Horizon”, 2019) in the range of 151 to 255, preferably in the range of 160 to 255, particularly preferably in the range of 180 to 255, most preferably in the range of 200 to 250.

[0109] The at least one (reflective) primer preferably contains or consists of at least one component selected from the group consisting of xylene isomers, hydrocarbons, preferably C6-C7 hydrocarbons, isoalkanes, cycles, n-hexane, and mixtures thereof. The at least one clear coat protective sealant preferably contains or consists of at least one component selected from the group consisting of acetone, 2-methoxy-1-methylethyl acetate, butan-1-ol, n-butyl acetate, and mixtures thereof. The clear coat protective sealant protects the retroreflective glass beads from external influences and simultaneously serves to ensure the adhesion of the retroreflective glass beads to the primer. All materials of the retroreflective marking(s) are preferably suitable for high temperature exposure, e.g., for temperatures above 1000 °C, preferably above 1500 °C.

[0110] The mean diameter of the retroreflective glass beads can be determined, for example, according to ISO 13320:2020-01.

[0111] The retroreflective glass beads - preferably contain or consist of soda-lime glass, and / or - preferably have a refractive index in the range of 1.6 to 2.2, and / or - preferably have a retroreflection value of at least 500 mcd / m 2 ·Ix, preferably of at least 1000 mcd / m² 2 ·Ix, particularly preferably of at least 1500 mcd / m² 2 ·Ix, on.

[0112] The refractive index can be determined, for example, according to DIN EN 1423:2013-03.

[0113] The retroreflection value can be determined, for example, according to DIN EN 1436: 2018-03.

[0114] The one or more retroreflective markings can each have at least one retroreflective (surface) surface.

[0115] The size and shape of the retroreflective marker(s) can be defined depending on the task, and / or can correlate with the scanning pattern of the ToF scanner or LiDAR scanner, and / or can influence the detection latency.

[0116] Another preferred embodiment of the crane according to the invention is characterized in that - the multiple components of the load-bearing system each have at least one, preferably at least two, particularly preferably at least three, and most preferably at least five, of the retroreflective markings, and / or - the multiple components of the load-bearing system have a total of at least two, preferably at least three, particularly preferably at least five, most preferably at least ten, retroreflective markings, and / or - each of the loads has at least one, preferably at least two, particularly preferably at least three, and most preferably at least five retroreflective markings.

[0117] Another preferred embodiment of the crane according to the invention is characterized in that the at least one ToF sensor - is attached to the crane, and / or - includes at least two, preferably at least four, ToF sensors, and / or - comprising at least one LiDAR sensor (light detection and ranging sensor), preferably at least two LiDAR sensors, particularly preferably at least four LiDAR sensors, wherein the at least one LiDAR sensor is preferably at least one ASIL-certified (Automotive Safety Integrity Level-certified) LiDAR sensor, particularly preferably at least one ASIL-certified LiDAR with embedded intelligence, and / or - comprising at least one ToF sensor with a limited field of view, preferably at least one LiDAR sensor with a limited field of view, or is at least one ToF sensor with a limited field of view, preferably at least one LiDAR sensor with a limited field of view, wherein one of the two angles is a maximum of 120° and the other of the two angles is a maximum of 30°, wherein the vertical angle is particularly preferably a maximum of 120° and / or the horizontal angle is a maximum of 30°.

[0118] The at least one LiDAR sensor may preferably be at least one ASIL-certified (Automotive Safety Integrity Level certified) LiDAR sensor, particularly preferably with embedded intelligence. In this case, it is especially preferred that the at least one LiDAR sensor includes at least one processing unit and that the at least one processing unit is additionally configured to perform an evaluation of the at least one visualized point cloud and / or the at least one digital twin, from which it is determined whether the at least one load is being handled correctly by the load-handling system.

[0119] The at least one ASIL-certified LiDAR sensor preferably comprises at least two, particularly preferably at least four, ASIL-certified LiDAR sensors.

[0120] The at least one ASIL-certified LiDAR sensor with embedded intelligence preferably comprises at least two, particularly preferably at least four, ASIL-certified LiDAR sensors with embedded intelligence.

[0121] The at least one LiDAR sensor with a limited field of view preferably comprises at least two, particularly preferably at least four, LiDAR sensors with a limited field of view.

[0122] The at least one LiDAR sensor can be at least one pulsed LiDAR sensor. This can increase the measurement accuracy.

[0123] Another preferred embodiment of the crane according to the invention is characterized in that the several components of the load handling system - include at least one rope, and / or - include a truss, and / or - include a trolley, and / or - comprise at least one, preferably at least two, load-handling devices, wherein the at least one load-handling device is preferably at least one crane hook, particularly preferably at least two crane hooks, and / or - comprises at least one, preferably at least two, fastening means for a load-bearing device, wherein the at least one fastening means is preferably at least one hook fork, preferably at least two hook forks.

[0124] For example, the traverse can be attached to the trolley via at least one rope and / or the at least one load-bearing device can be attached to the traverse via at least one fastening device.

[0125] Particularly preferably, the several components of the load-bearing system comprise a crossbeam, wherein the crossbeam has one or more retroreflective markings (or the one retroreflective marking or one or more of the retroreflective markings).

[0126] The multiple components particularly preferably comprise a trolley, at least one rope, a crossbeam, at least two load-handling devices, preferably at least two crane hooks, and at least two attachment points for the load-handling devices, preferably at least two hook forks. It is preferred that the crossbeam has one or more retroreflective markings (or the single retroreflective marking or one or more of the retroreflective markings). For example, the crossbeam can be attached to the trolley via the at least one rope, preferably via several ropes, and / or the at least two load-handling devices can be attached to the crossbeam via the at least two attachment points.

[0127] Another preferred embodiment of the crane according to the invention is characterized in that - which is configured to process the at least one point cloud, in which the at least one point cloud is visualized and / or at least one digital twin of at least one part of the load-bearing system and / or the at least one load is generated (and visualized), and optionally • the system additionally includes at least one evaluation unit configured to perform an evaluation of the at least one visualized point cloud and / or the at least one (visualized) digital twin, in which it is derived whether the at least one load is handled correctly by the load handling system (preferentially picked up, transported, delivered, and / or is picked up or held), or • which is configured to perform an evaluation of the at least one visualized point cloud and / or the at least one (visualized) digital twin, in which it is derived whether the at least one load is handled correctly by the load handling system (preferentially picked up, transported, delivered, and / or is picked up or held), and / or - the load-bearing system has several, preferably at least three, particularly preferably at least four, most preferably at least five, retroreflective markings, wherein the retroreflective markings are arranged together from one or more viewing directions in a predefined pattern, preferably in a predefined ASIL-compliant pattern, wherein preferably at least two of the several components of the load-bearing system each have at least one of the several retroreflective markings, and / or - the at least one ToF sensor comprising at least one processing unit, wherein preferably the at least one processing unit is additionally configured to perform an evaluation of the at least one visualized point cloud and / or the at least one (visualized) digital twin, in which it is derived whether the at least one load is handled correctly by the load-bearing system.

[0128] The at least one processing unit can be at least one computing unit or at least one computer configured to process the at least one point cloud, in which the at least one point cloud is visualized and / or at least one digital twin of at least one part of the load-bearing system and / or the at least one load is generated (and visualized).

[0129] The at least one evaluation unit can be at least one computing unit or at least one computer configured to perform an evaluation of the at least one visualized point cloud and / or the at least one (visualized) digital twin, in which it is derived whether the at least one load is handled correctly by the load handling system (preferentially picked up, transported, delivered, and / or is picked up or held).

[0130] The at least one processing unit and / or the at least one evaluation unit may comprise a process analysis system.

[0131] The predefined pattern could be, for example, a line, parallel lines, a cross, a U-shaped pattern, or an H-shaped pattern.

[0132] Another preferred embodiment of the crane according to the invention is characterized in that the system (for checking and / or monitoring a load handling system of the crane) is suitable for carrying out the method according to the invention.

[0133] The present invention will be explained in more detail with reference to the following figures and examples, without limiting it to the specific embodiments and parameters shown here.

[0134] In Fig. Figure 1 shows two views of an exemplary embodiment of the crane 10 according to the invention, with a side view on the left and a top view on the right. The crane 10 comprises a system for checking and / or monitoring a load-handling system of the crane 10, comprising several components and designed for handling at least one load. The system includes four ToF sensors 8 for generating at least one point cloud of a working area in which the load-handling system is at least partially arranged. These sensors are mounted on the crane 10. The four ToF sensors 8 are LiDAR sensors with a limited field of view. The lines emanating from the LiDAR sensors in Fig. The numbers 1 here indicate the limited field of view, which is defined by a vertical angle and a horizontal angle. Furthermore, it includes a processing unit for processing the at least one point cloud, whereby the processing unit is not in Fig. 1 is shown.

[0135] The load handling system of crane 10 of the in Fig. The exemplary embodiment shown in 1 is in Fig. 2 and Fig. Figure 3 shows enlarged illustrations in two views from different sides. The load handling system comprises a trolley 1, a spreader beam 2, two hook forks 3, two crane hooks 4, and ropes connecting the spreader beam 2 to the trolley 1. A load 6, a ladle with ladle pins 5, is also shown. The ladle pins 5 can be attached to the crane hooks 4 by the load handling system to lift the ladle.

[0136] The load handling system of crane 10 has several retroreflective markings 7 that reflect at least some of the light emitted by the ToF sensors 8 back onto the ToF sensors 8. For better clarity, the retroreflective markings 7 are only shown in Fig. 3, however, not in Fig. 1 and Fig. 2 shown.

[0137] The retroreflective markings are applied to the crossbeam 2, the hook forks 3, the crane hooks 4 and the load 6.

[0138] As in Fig. As can be seen in Figure 3, the retroreflective markings are arranged in a predefined pattern from at least two viewing directions. In the left view in Fig. In the 3rd image, the retroreflective markings form a cross-shaped pattern. In the right-hand view in Fig. 3. If the retroreflective markings form a "U" shape, and the markings are arranged in the respective predefined pattern from both viewing directions, it can be deduced that at least one load is being handled correctly by the load-bearing system, in particular that it is being lifted or held.

[0139] Fig.Figure 4 shows an alternative exemplary embodiment of the crane 10 according to the invention in a top view of a cross-section. Retroreflectors 7 can be attached to a component of the load-handling system or a casting ladle at an angle of preferably 44° to 46° to a main direction of movement of the crane 10. If each point from the LiDAR scan in the resulting point cloud is annotated with a different color due to the strength of its reflectivity, the angled retroreflective surfaces can be clearly seen in several main views of the point cloud without requiring extensive computational steps. In this example, the retroreflective surfaces will be seen at the same size in both the side and front views by the virtual eye 9. Example of implementation

[0140] An exemplary embodiment of the inventive method is intended to inspect and / or monitor a multi-component load-handling system of a crane designed for handling a casting ladle. The crane has four time-of-flight (ToF) sensors. Furthermore, several components of the load-handling system and / or the load (or the casting ladle) have retroreflective markings that reflect at least some of the light emitted by the four ToF sensors back onto the ToF sensors.

[0141] It should be checked and / or monitored whether the ladle is handled correctly by the load-bearing system.

[0142] The four sensors mounted on the crane continuously transmit their data (3D point with reflectivity value) to the object detection system. This system collects the sensor data and stores it for a certain period (integration time) for data processing purposes.

[0143] For an upcoming analysis of the current state, data from, for example, the last 200 ms are retrieved. The point clouds from the individual sensors are not yet in a uniform coordinate system, as each sensor transmits the data in its own proprietary coordinate system. Therefore, all points are first transformed. The necessary transformations were determined during the commissioning of the entire system based on the calibration of the sensors.

[0144] The positions and orientations of the traverse, crane hook, and casting ladle are determined in parallel using two different methods within the point cloud. In the geometry-based analysis, 3D geometry models of the components are fitted into the point cloud based solely on its appearance. In the marker-based analysis, the positions of the objects are determined by locating the retroreflective markers within the point cloud. The results of the two approaches are then combined and tested for consistency. This increases the reliability of the system, as both analysis methods must produce similar results to ensure that all objects have been correctly identified and located.

[0145] In the geometry-based approach, the load cables of the truss are first determined. Due to the rigid mounting of the sensors on the crane, various regions of interest (ROIs) are defined in the point cloud in the form of bounding boxes aligned with the coordinate axes. The points within these boxes, one for the left and one for the right load cable, are analyzed, and the cables are located based on their high point density and their vertically oriented, thin structures. Since it is known that the truss must be located below the cables, the cables are traced downwards in the point cloud. At the end of the cable point clouds, the 3D model of the truss is placed in space. This initial estimate of the actual truss position now needs to be further refined.To reduce the effort, points within a region of interest (ROI) around the estimated traverse position are first extracted, and the traverse model is then iteratively fitted into the point cloud using the ICP algorithm. The crane hooks are located below the traverse. Based on the load system design, an initial estimate of the crane hook positions is derived from the previously determined traverse position. This initial position estimate is then refined using the ICP algorithm. Finally, the ladle is located in the point cloud. It is known that ladles relevant to the monitoring process must be located below and in front of the traverse in the trolley's direction of travel, as well as between the two crane hooks. Again, this prior knowledge allows the point cloud to be reduced to the relevant area using a corresponding ROI.Since the diameter of the ladle is known, suitable areas with the appropriate curvature for the ladle's position are identified in the remaining point cloud. These point cloud segments are then evaluated for their suitability based on the number of points that can be reliably assigned to the ladle's surface, and the best point cloud segment is selected. The position of the 3D model for the ladle is then further refined using an ICP algorithm. After this process, the positions and orientations of all objects to be detected within the crane's working area are known.

[0146] In the marker-based approach, the point cloud is first analyzed based on its reflectivity values. The points generated on the retroreflective markers exhibit significantly higher reflectivity than the remaining points in the point cloud. Points above the threshold of 151 are extracted and grouped into local point cloud clusters based on their spatial proximity. The positions of the retroreflective markers within the point cloud are then determined. The relative arrangement of the retroreflective markers and their exact positions on the objects to be detected are known. From this, a mapping of the retroreflective markers in the point cloud to the positions stored in the model is derived. Based on this mapping, the transformations to the actual position in the point cloud are then determined for each object.

[0147] After both methods have delivered a result and this has been checked for consistency, the transformations of the objects are converted into an exchange data format and transmitted via a data protocol to a process analysis system and a visualization system.

[0148] The next detection procedure then starts.

[0149] The visualization system displays the point cloud and / or the digital twin, which can then be shown on a screen. By viewing the visualized point cloud and / or the digital twin, a person and / or an evaluation unit can determine whether the ladle is being handled correctly by the load-bearing system. The process analysis system can also be used for this purpose.

[0150] The movement data of the individual crane components and the load are transmitted to the process analysis system 4 to 10 times per second with regard to their position (x,y,z) and their orientation (x rotation, y rotation, z rotation).

[0151] The process analysis system uses rule-based algorithms to check the movement speeds, maximum / minimum distances, and inclination angles between components for each parameter set and classifies the results regarding the proper functioning of the handling process for the load-handling system. Furthermore, stored parameter sets for the correct relative positions of components within a load-handling system, according to mechanical equilibrium, are also used for process analysis. This allows for the detection of a jammed hook that no longer realigns itself. The positions and orientations of the two crane hooks are analyzed relative to each other to ensure the parallelism of the hook movement during lifting and unloading.

[0152] The motion data of the load-handling system components are interpreted over time to identify and assess their speed and dynamics. Typical motion characteristics are identified from the displacement / time diagrams for each component, and abnormalities such as oscillation of the crossbeam are investigated. This allows for a warning to be issued even if a dangerous equilibrium situation develops. Many tests are performed redundantly to increase the reliability of the results and to make the regulatory framework increasingly safer in terms of the functional safety of the work system. The following rules can be checked in this process: - If the position of the hook mouth center and the pin center of the casting ladle coincide within a certain tolerance range of, for example, < 100 mm, the pin is securely in the hook mouth. - When picking up or dropping off the ladle, the hook tip must be guided safely below the pin, because otherwise the ladle may be turned or pulled into an unclear position upon contact with a crane hook, or in extreme cases, tip over. - If the hook tip of the crane hook lifts the pin of the ladle, thus bringing the component group into an unstable equilibrium, in extreme cases the pin slips outwards from the crane hook tip and the ladle tips over.

Claims

[1] Method for checking and / or monitoring a multi-component load handling system of a crane (10) designed for handling at least one load (6), in which a) using at least one ToF sensor (8) at least one point cloud of a work area is generated in which the load handling system is at least partially arranged, wherein the load handling system has one or more retroreflective markings (7) which reflect light emanating from the at least one ToF sensor (8) at least partially back onto the at least one ToF sensor (8), b) the at least one point cloud is processed, whereby at least one digital twin of at least one part of the load-bearing system is generated based on the at least one point cloud and c) an evaluation of the at least one digital twin is carried out, in which it is derived whether the at least one load (6) is handled correctly by the load handling system by ensuring that there is no misalignment of the at least one load (6) relative to the load handling system. [2] Method according to the preceding claim, characterized by , that one or more retroreflective markings (7) - each containing or consisting of at least one primer and retroreflective glass beads, and optionally at least one clear coat protective sealant, wherein the retroreflective glass beads preferably have a mean diameter in the range of 0.1 mm to 0.3 mm, and / or - each formed flat, preferably each rectangular, are, and / or, - each have a length and / or width of at least 150 mm, preferably at least 200 mm, and / or - each have a size and / or shape that correlates with a scanning pattern of the at least one ToF sensor (8), and / or - the one or more retroreflective markings (7) each have a retroreflective surface which is arranged at an angle of 30° to 60°, preferably 40° to 50°, particularly preferably 44° to 46°, to a main direction of movement of the crane. [3] Method according to any one of the preceding claims, characterized by , that - the multiple components of the load-bearing system each have at least one, preferably at least two, particularly preferably at least three, most preferably at least five, of the retroreflective markings (7), and / or - the multiple components of the load-bearing system have a total of at least two, preferably at least three, particularly preferably at least five, most preferably at least ten, of the retroreflective markings (7), and / or - the at least one load (6) has at least one, preferably at least two, particularly preferably at least three, most preferably at least five, of the retroreflective markings (7). [4] Method according to any one of the preceding claims, characterized by , that the at least one ToF sensor (8) - is attached to the crane (10), and / or - comprises at least two, preferably at least four, ToF sensors (8), and / or - comprising at least one LiDAR sensor, preferably at least two LiDAR sensors, particularly preferably at least four LiDAR sensors, wherein the at least one LiDAR sensor is preferably at least one ASIL-certified LiDAR sensor, and / or - includes at least one ToF sensor with a limited field of view or is at least one ToF sensor with a limited field of view, wherein the limited field of view is defined by two angles comprising a vertical angle and a horizontal angle, one of the two angles being a maximum of 120° and the other of the two angles being a maximum of 30°. [5] Method according to any one of the preceding claims, characterized by that the several components of the load-bearing system - include at least one rope, and / or - include a truss (2), and / or - include a trolley (1), and / or - comprise at least one, preferably at least two, load-handling devices, wherein the at least one load-handling device is preferably at least one crane hook (4), particularly preferably at least two crane hooks (4), and / or - comprising at least one, preferably at least two fastening means for a load-bearing device, wherein the at least one fastening means is preferably at least one hook fork (3), preferably at least two hook forks (3). [6] Method according to any one of the preceding claims, characterized by , that Additionally in step a) the at least one load (6) has one or more retroreflective markings (7) that reflect light emanating from the at least one ToF sensor (8) at least partially back onto the at least one ToF sensor (8) and / or additionally in step b) processing of the at least one point cloud takes place, whereby at least one digital twin of the at least one load is generated based on the at least one point cloud. [7] Method according to claim 1, characterized by , that the at least one digital twin is generated using at least one geometry fitting process in which at least one three-dimensional model of at least one part of the load-bearing system is transformed into the at least one point cloud, wherein in the at least one geometry fitting process - at least one shape-based geometry fitting is performed, in which preferably the at least one three-dimensional model is transformed into the at least one point cloud in such a way that at least partial geometric agreement is achieved between the at least one point cloud and the at least one three-dimensional model, wherein the mean deviation of the points of the at least one three-dimensional model from the points of the point cloud is at most 20 cm, preferably at most 15 cm, particularly preferably at most 10 cm, and most preferably at most 5 cm, and / or - at least one geometry fitting based on the one or more retroreflective markings (7) is performed, in which preferably the at least one three-dimensional model is transformed into the at least one point cloud in such a way that one or more areas of the at least one point cloud, which are characterized by an increased reflection caused by the one or more retroreflective markings (7), are assigned to one or more corresponding areas of the at least one three-dimensional model. [8] Method according to claim 7, characterized by , that before carrying out at least one geometry fitting process - the at least one three-dimensional model is parameterized, preferably by varying parameters that characterize the multiple components of the load-bearing system and / or the at least one load (6) in the three-dimensional model during an initial point cloud acquisition, and then selecting a suitable parameter sequence and using it for the geometry fitting process, and / or - the size of the at least one three-dimensional model is adjusted, wherein preferably the one or more retroreflective markings (7) are arranged at a predefined distance to at least one edge or at least one surface of the at least one load (6) or one of the several components of the load-bearing system, and the size of the at least one three-dimensional model is adjusted based on a determined position and / or orientation of the one or more retroreflective markings (7). [9] Method according to claim 1, characterized by that the load-bearing system and / or the at least one load (6) have several of the retroreflective markings (7), wherein the retroreflective markings (7) are arranged together from one or more viewing directions in a predefined pattern, preferably in a predefined ASIL-compliant pattern, only if the at least one load (6) is handled correctly by the load-bearing system, wherein the evaluation in step c) is based on the at least one visualized point cloud to determine whether the several retroreflective markings (7) are arranged together from one or more viewing directions in the predefined pattern, and from this it is deduced whether the at least one load (6) is handled correctly by the load-bearing system, wherein preferably - at least two of the several components of the load-bearing system each have at least one of the several retroreflective markings (7), and / or - in addition, at least one load has one of the several retroreflective markings (7). [10] Crane (10) comprising a system for checking and / or monitoring a load handling system of the crane (10) comprising several components for handling at least one load (6), wherein the system comprises at least one ToF sensor (8) for generating at least one point cloud of a working area in which the load handling system is at least partially located, wherein the system further comprises at least one processing unit for processing the at least one point cloud, wherein the processing unit is configured to generate at least one digital twin of at least one part of the load-bearing system based on the at least one point cloud and to perform an evaluation of the at least one digital twin in which it is derived whether the at least one load (6) is handled correctly by the load-bearing system by ensuring that there is no misalignment of the at least one load (6) relative to the load-bearing system and wherein the load handling system has one or more retroreflective markings (7) which reflect at least some of the light emanating from the at least one ToF sensor (8) back onto the at least one ToF sensor (8). [11] Crane according to claim 10, characterized by , that one or more retroreflective markings (7) - each containing or consisting of at least one primer and retroreflective glass beads, and optionally at least one clear coat protective sealant, wherein the retroreflective glass beads preferably have a mean diameter in the range of 0.1 mm to 0.3 mm, and / or - each formed flat, preferably each rectangular, are, and / or, - each have a length and / or width of at least 150 mm, preferably at least 200 mm, and / or - each have a size and / or shape that correlates with a scanning pattern of the at least one ToF sensor (8), and / or - the one or more retroreflective markings (7) each have a retroreflective surface which is arranged at an angle of 30° to 60°, preferably 40° to 50°, particularly preferably 44° to 46°, to a main direction of movement of the crane. [12] Crane according to claim 10 or 11, characterized by , that - the multiple components of the load-bearing system each have at least one, preferably at least two, particularly preferably at least three, most preferably at least five, of the retroreflective markings (7), and / or - the several components of the load-bearing system have a total of at least two, preferably a total of at least three, particularly preferably a total of at least five, most preferably a total of at least ten, of the retroreflective markings (7). [13] Crane according to one of claims 10 to 12, characterized by that it has at least one ToF sensor - is attached to the crane (10), and / or - comprises at least two, preferably at least four, ToF sensors (8), and / or - comprising at least one LiDAR sensor, preferably at least two LiDAR sensors, particularly preferably at least four LiDAR sensors, wherein the at least one LiDAR sensor is preferably at least one ASIL-certified LiDAR sensor, and / or - includes at least one ToF sensor with a limited field of view or is at least one ToF sensor with a limited field of view, wherein the limited field of view is defined by two angles comprising a vertical angle and a horizontal angle, one of the two angles being a maximum of 120° and the other of the two angles being a maximum of 30°. [14] Crane according to any one of claims 10 to 13, characterized by that the several components of the load-bearing system - include at least one rope, and / or - include a truss (2), and / or - include a trolley (1), and / or - comprise at least one, preferably at least two, load-handling devices, wherein the at least one load-handling device is preferably at least one crane hook (4), particularly preferably at least two crane hooks (4), and / or - comprising at least one, preferably at least two fastening means for a load-bearing device, wherein the at least one fastening means is preferably at least one hook fork (3), preferably at least two hook forks (3). [15] Crane according to any one of claims 10 to 14, characterized by , that - which is configured to process the at least one point cloud, in which the at least one point cloud is visualized and / or at least one digital twin of at least one part of the load-bearing system and / or the at least one load (6) is generated, and optionally • the system additionally includes at least one evaluation unit configured to perform an evaluation of the at least one visualized point cloud and / or the at least one digital twin, from which it is derived whether the at least one load (6) is handled correctly by the load-bearing system, or • which is additionally configured to perform an evaluation of the at least one visualized point cloud and / or the at least one digital twin, in which it is derived whether the at least one load (6) is handled correctly by the load-bearing system, and / or - the load-bearing system has several of the retroreflective markings (7), wherein the retroreflective markings (7) are arranged together from one or more viewing directions in a predefined pattern, preferably in a predefined ASIL-compliant pattern, wherein preferably at least two of the several components of the load-bearing system each have at least one of the several retroreflective markings, and / or - the at least one ToF sensor (8) comprising at least one processing unit, wherein preferably the at least one processing unit is additionally configured to perform an evaluation of the at least one visualized point cloud and / or the at least one digital twin, in which it is derived whether the at least one load is handled correctly by the load-bearing system, and / or - the system is suitable for carrying out a method according to any one of claims 1 to 9.

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