Method for two-dimensional determination of a current deflection and rotation of a load receiving means held on a trolley of a crane system

Abstract

The invention relates to a method for the two-dimensional determination of the current deflection and rotation of a load-handling device (4) held on a trolley (2) of a crane system (1) relative to a rest position of the load-handling device (4). The invention further relates to a system designed for carrying out the method and a crane system (1) designed for carrying out the method.

Description

[0001] The present invention relates to a method for the two-dimensional determination of a current deflection and rotation of a load-handling device held on a trolley of a crane system relative to a rest position of the load-handling device. Furthermore, the present invention relates to a crane with a trolley and a load-handling device arranged on the trolley, comprising a camera arranged on the underside of the trolley, which is oriented such that it captures the top side of the load-handling device, and an evaluation unit configured to carry out a method according to the invention.

[0002] Crane systems with a trolley and a load handling device, usually attached to the trolley via suspension cables and designed, for example, to lift commercially available containers, are known in a wide variety of designs. In such crane systems, the load picked up by the lifting device can be moved three-dimensionally in space by moving the trolley on the one hand and by changing the length of the suspension cables on the other. During operation of the crane system, the load handling device experiences deflections and / or twists, which must be compensated for, particularly during automatic unloading and loading cycles. Accordingly, current deflections and twists of the trolley are automatically determined relative to a rest position of the load handling device in order to control a vibration damping system acting on the load handling device based on these deflections and twists.

[0003] A known method for the two-dimensional determination of the current deflection and rotation of a load-handling device held on a trolley of a crane system relative to a rest position of the load-handling device is described in DE 198 36 103 A1. In this method, a semiconductor camera attached to the trolley of the crane system records an image of a reflector attached to the top of the load-handling device, which is illuminated by an infrared illumination unit positioned directly next to the semiconductor camera. In the camera's video image, the reflector represents an analyzable surface that can be compared with a reference surface of the reflector in the rest position of the load-handling device, stored in an evaluation unit. Based on such a comparison, the current deflection and / or rotation of the load-handling device relative to the rest position of the load-handling device can be calculated.In principle, this well-known method has proven itself in practice. However, one disadvantage of the method is that, depending on the design of the load-handling device, mounting the reflector can prove difficult, for example because very little installation space is available. If an active reflector is used as the reflector, an additional power supply is required on the load-handling device, which usually also entails considerable effort. In addition, an additional heater is often required to keep the reflector free of snow and thus ensure the functionality of the system. In the event of a defect in the load-handling device, it must also be ensured that the same reflector is installed in the same position on the replacement load-handling device. Otherwise, complex recalibration is necessary.Finally, in addition to the semiconductor camera, a reflector and an infrared illumination unit are required to carry out the process, which entails comparatively high costs.

[0004] Based on this prior art, it is an object of the present invention to provide an improved method of the type mentioned at the outset and a crane system designed to carry out the method.

[0005] To achieve this object, the present invention provides a method for the two-dimensional determination of a current deflection and rotation of a load-handling device held on a trolley of a crane system relative to a rest position of the load-handling device, which method comprises the steps: a) Arranging a camera on the trolley such that the camera captures the top side of the load handling device; b) Capturing an image of the top side of the load handling device in a rest position of the load handling device and saving this rest position image; c) Capturing a current image of the top side of the load handling device during operation of the crane system while the load handling device is not in the rest position; d) Capturing a plurality of geometric features specific to the load handling device present on the top side of the load handling device in the current camera image captured in step c); e) Searching for the geometric features captured in step d) in the rest position image; and f) Determining the current two-dimensional deflection and rotation of the geometric features relative to their rest position by comparing the positions of the geometric features in the current image with the positions of the geometric features in the rest position image.

[0006] A conventional digital video camera can be selected as the camera mounted on a trolley in step a), thereby minimizing the cost of purchasing the camera. The geometric features recorded in step d) are inherent features of the load handling device, which has the advantage that no additional components need to be positioned on top of the load handling device, such as the reflectors or the like described above. A further advantage associated with selecting inherent geometric features of the load handling device is that, in the event of a defect, the load handling device can simply be replaced with a new one of the same type without the need for subsequent recalibration of the geometric features.

[0007] Overall, the present invention provides a very cost-effective method for detecting current pendulum movements of the load-handling device.

[0008] According to a first embodiment of the method according to the invention, the features detected in step d) are predetermined features that are stored in an evaluation unit after they have been determined. Thus, the same geometric features are always detected in current camera images and compared with those in the rest position image in step f) to determine the respective current two-dimensional deflection and rotation of the geometric features. Thus, step e) is not performed for each new current camera image, but only once, since the positions of the geometric features in the rest position image do not change and can therefore be easily stored.

[0009] According to a second embodiment of the method according to the invention, the features detected in step d) are features automatically selected by the software used, which may vary from one current camera image to another. Accordingly, step e) must be performed for each new current camera image. This automatic selection of geometric features has the advantage that a correct determination of the current two-dimensional deflection and rotation of the geometric features relative to their rest position is always possible, even under changing lighting conditions and shadows.In the event of a load handling device failure, it can simply be replaced with a new one, regardless of whether the new load handling device has the same design as the old one, since the geometric characteristics are not fixed but are automatically reselected each time the procedure is performed. Only the rest position image needs to be re-taken once.

[0010] According to one embodiment of the present invention, the determination of the current deflection and rotation of the load-carrying device in step f) is carried out by means of digital image processing, which is advantageous with regard to the processing speed.

[0011] Preferably, steps c) to f) are repeated multiple times at short, consecutive intervals, with a movement cycle of the load-handling device being determined based on the successive current deflections and rotations of the load-handling device. Based on such movement cycles, vibration damping can be optimally controlled.

[0012] According to one embodiment of the method according to the invention, control commands are created in the evaluation unit based on the current deflections and rotations of the load-handling device determined in step f) and forwarded to a vibration damping system acting on the load-handling device, which is then controlled based on the control commands.

[0013] Furthermore, to achieve the object mentioned above, the present invention provides a system comprising a camera, in particular a digital camera, and an evaluation unit which is designed to carry out a method according to the invention.

[0014] Advantageously, the system also comprises a vibration damping system.

[0015] Furthermore, to achieve the object mentioned at the outset, the present invention provides a crane system with a trolley and a load-handling device arranged on the trolley, comprising a camera arranged on the underside of the trolley, which is aligned such that it detects the upper side of the load-handling device, an evaluation unit which is designed to carry out a method according to one of the preceding claims, and a vibration damping system acting on the load-handling device, which is controlled via the evaluation unit.

[0016] Further features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. Figure 1 is a schematic side view of a crane system according to an embodiment of the present invention and Figure 2 is a schematic perspective top view of a load-carrying device of the Figure 1 crane system shown.

[0017] Figure 1 shows a crane system 1 with a trolley 2 that is motor-driven in the X and Y directions, to which a load-handling device 4 is attached via suspension cables 3 that are motor-driven in the Z direction. The load-handling device 4 can be one designed to accommodate commercially available containers, to name just one example.

[0018] To carry out a method according to an embodiment of the present invention for the two-dimensional determination of a current deflection and rotation of the load-handling device 4 held on the trolley 2 relative to a rest position of the load-handling device 4, in a first step a camera 5 is arranged on the trolley 2 such that it captures the upper side of the load-handling device 4, as indicated in the figure by the dashed lines 6. The camera 5 is a conventional digital video camera in the present case. Furthermore, an evaluation unit 7 and a vibration damping system 8 are positioned, in this case on the trolley 2. The evaluation unit 7 and the vibration damping system 8 can, however, also be arranged at other positions and / or integrated into existing components of the crane system 1.

[0019] In a further step, an image of the top side of the load-handling device 4 in a rest position of the load-handling device 4 is taken with the camera 5 and this rest position image is stored in the evaluation unit 7.

[0020] During the subsequent operation of the crane system 1, the camera 5 takes current images of the top side of the load handling device 4 and transmits them to the evaluation unit 7. In the evaluation unit 7, the geometric features 9, 10, 11 present on the top side of the load handling device 4 and specific to the load handling device 4 are then automatically selected in each current camera image. These geometric features 9, 10, 11 are then searched for in the rest position image, whereupon the current two-dimensional (XY plane in Figure 1) Deflection and rotation of the geometric features 9, 10, 11 relative to their rest position is determined by comparing the positions of the geometric features 9, 10, 11 in the current image with the positions of the geometric features 9, 10, 11 in the rest position image. Based on the current deflection and rotation, the evaluation unit 7 generates signals for controlling the vibration damping system 8 and forwards them to the vibration damping system 8. The more current camera images are recorded in a predetermined period of time and evaluated in the manner described above, the more accurately the movement cycle of the load handling device 4 can be determined based on the successive current deflections and rotations of the load handling device 4, which enables optimized vibration damping.

[0021] A significant advantage of the method described above is that only a few components are required to carry it out, namely just a camera 5, an evaluation unit 7 and a vibration damping system 8. Additional components such as reflectors or infrared illumination units are omitted, which results in a very cost-effective structure.

[0022] The geometric features 9, 10, and 11 are automatically redefined for each current camera image. Accordingly, the geometric features of different current camera images can differ from one another. This has the advantage of allowing a correct determination of the current two-dimensional deflection and rotation of the geometric features relative to their rest position, even under changing lighting conditions and shadows.

[0023] In the event of a defect in the load handling device 4, it can simply be replaced with a new one without the need for subsequent recalibration of the geometric features 9, 10, and 11. If a new load handling device is selected whose design differs from the old load handling device 4, only a new rest position image needs to be recorded and saved. Furthermore, the camera stream recorded by camera 5 can also be used, for example, by the crane operator or a remote operator, which is another advantage.

[0024] According to an alternative embodiment of the method described above, the features 9, 10, and 11 captured in the current camera image can be predefined features. Accordingly, these features 9, 10, and 11 only need to be searched for once in the resting image and then stored, since they remain constant.

[0025] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited to the disclosed examples and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.

[0026] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

Claims

1. A method for the two-dimensional determination of a current deflection and rotation of a load-handling device (4) held on a trolley (2) of a crane system (1) relative to a rest position of the load-handling device (4), comprising the steps of: a) arranging a camera (5) on the trolley (2) such that the camera (5) captures the upper side of the load-handling device (4); b) recording an image of the upper side of the load-handling device (4) in a rest position of the load-handling device (4) and storing this rest position image; c) recording a current image of the upper side of the load-handling device (4) during operation of the crane system (1), while the load-handling device (4) is not in the rest position; d) capturing a plurality of geometric features (9, 10, 11) present on the upper side of the load-handling device (4) and specific to the load-handling device (4) in the current camera image captured in step c);e) searching for the geometric features (9, 10, 11) detected in step d) in the rest position image; and f) determining the current two-dimensional deflection and rotation of the geometric features (9, 10, 11) relative to their rest position by comparing the positions of the geometric features (9, 10, 11) in the current image with the positions of the geometric features (9, 10, 11) in the rest position image.

2. Method according to claim 1, characterized in that the characteristics (9, 10, 11) recorded in step d) are predetermined characteristics.

3. Method according to claim 1, characterized in that the characteristics (9, 10, 11) recorded in step d) are automatically selected characteristics.

4. Method according to one of the preceding claims, characterized in that the determination of the current deflection and rotation of the load-handling device (4) in step f) is carried out by means of digital image processing.

5. Method according to one of the preceding claims, characterized in that steps c) and f) are repeated many times at short successive time intervals, and that a movement cycle of the load-handling device (4) is determined based on the successive current deflections and rotations of the load-handling device (4).

6. Method according to one of the preceding claims, characterized in that Based on the current deflections and rotations of the load-handling device (4) determined in step f), control commands are created in the evaluation unit (7) and forwarded to a vibration damping system (8) acting on the load-handling device (4), which is then controlled based on the control commands.

7. System comprising a camera (5), in particular a digital camera, and an evaluation unit (7) which is designed to carry out a method according to the invention.

8. System according to claim 7, further comprising a vibration damping system (8).

9. Crane system (1) with a trolley (2) and a load-handling device (4) arranged on the trolley (2), comprising a camera (5) arranged on the underside of the trolley (2) which is aligned such that it detects the top side of the load-handling device (4), an evaluation unit (7) which is set up to carry out a method according to one of the preceding claims, and a vibration damping system (5) acting on the load-handling device (4) which is controlled via the evaluation unit (7).

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