Method for two-dimensionally determining current deflection and rotation of load-receiving device mounted on trolley of lifting appliance

Abstract

The invention relates to a method for two-dimensionally determining the current deflection and rotation of a load-receiving device (4) supported on a trolley (2) of a lifting appliance (1) relative to a free position of the load-receiving device (4). The invention also relates to a system designed to carry out the method and to a hoisting device (1) designed to carry out the method.

Description

Technical Field

[0001] This invention relates to a method for two-dimensionally determining the current deflection and rotation of a load receiving device supported on a trolley of a lifting device relative to its idle position. Furthermore, the invention relates to a lifting device having a trolley and a load receiving device disposed on the trolley, the lifting device further comprising: a camera disposed on the bottom surface of the trolley and oriented to acquire the top surface of the load receiving device; and an evaluation unit designed to perform the method according to the invention. Background Technology

[0002] Numerous lifting devices with varying configurations are known in the prior art, comprising a trolley and a load-receiving device typically suspended from the trolley by a carrying rope or line. This load-receiving device is, for example, designed to accommodate containers for commercial sale. In such lifting devices, the load carried by the receiving device can be moved three-dimensionally in space by moving the trolley on one hand and by changing the length of the carrying rope on the other. During operation of the lifting device, the load-receiving device may deflect and / or rotate, requiring stabilization, especially during automatic unloading and loading cycles. Accordingly, the current deflection and rotation of the trolley relative to the idle position of the load-receiving device are automatically determined in order to control the vibration damping system acting on the load-receiving device.

[0003] DE 198 36 103 A1 describes a known method for two-dimensionally determining the current deflection and rotation of a load receiving device supported on a crane trolley of a lifting device relative to its idle position. In this method, a semiconductor camera fixed to the crane trolley records an image of a reflector mounted on the top surface of the load receiving device, illuminated by an infrared illumination unit located directly next to the semiconductor camera. The reflector appears as an evaluable surface in the camera's video image, which can be compared to a reference surface of the reflector stored in the evaluation unit when the load receiving device is in its idle position. Through this comparison, the current deflection and / or rotation of the load receiving device relative to its idle position can be calculated. Essentially, this known method has been validated in practice. However, a drawback of this method is that, depending on the design of the load receiving device, installing the reflector can be difficult, for example, when only very limited installation space is available. If an active reflector is used, an additional power supply to the load receiving device is required, which typically involves considerable workload. Furthermore, additional heating devices are usually required to keep the reflector snow-free, thus ensuring the proper functioning of the system. Furthermore, in the event of a load receiver failure, it is essential to ensure that the same reflector is installed in the same position on the replacement load receiver. Otherwise, complex recalibration is required. Finally, in order to implement this method, in addition to the semiconductor camera, a reflector and an infrared illumination unit are also required, which leads to relatively high costs.

[0004] Other methods for determining the current deflection and rotation of a load receiving device supported on a crane supported on a lifting device in two dimensions are also known from CN 111483914 A and US 2007 / 289931 A1. Summary of the Invention

[0005] Based on the prior art, the object of the present invention is to provide an improved method as described in the opening section, and a lifting device for performing the method.

[0006] To achieve this objective, the present invention proposes a method for two-dimensionally determining the current deflection and rotation of a load receiving device supported on a crane trolley of a lifting device relative to its idle position, the method comprising the following steps: a) Position the camera on the crane so that it can capture an image of the top surface of the load receiving device; b) Record an image of the top surface of the load receiving device at its idle position and store the idle position image; c) During the operation of the lifting equipment, when the load receiving device is not in an idle position, record the current image of the top surface of the load receiving device; d) Obtain multiple geometric features that exist on the top surface of the load receiving device and are unique to the load receiving device from the current image of the camera recorded in step c); e) Search the available location image for the geometric features obtained in step d); and f) Determine the current 2D deflection and rotation of the geometric feature relative to its idle position by comparing the position of the geometric feature in the current image with the position of the geometric feature in the idle position image.

[0007] A conventional digital video camera can be selected as the camera mounted on the crane in step a), thereby minimizing the camera's procurement cost. The geometric characteristics detected in step d) are specific to the load receiver, which has the advantage of eliminating the need for additional components, such as the aforementioned reflector or similar devices, on the top surface of the load receiver. Another advantage of using the load receiver's specific geometry is that, in the event of a failure, the load receiver can be directly replaced with a new load receiver of the same design without subsequent recalibration of the geometry.

[0008] Overall, the present invention provides a very economical method for obtaining the current oscillation motion of a load receiving device.

[0009] According to a first embodiment of the method of the present invention, the characteristic acquired in step d) is a predefined characteristic, which is stored in the evaluation unit after being set. Therefore, the same geometric characteristic is always acquired in the current camera image, and in step f), this geometric characteristic is compared with the characteristic in the idle position image to determine the current corresponding two-dimensional deflection and rotation of the geometric characteristic. Thus, step e) is not repeated for every new current camera image, but is only performed once, because the position of the geometric characteristic in the idle position image does not change and can be stored accordingly simply.

[0010] According to a second embodiment of the method of the present invention, the characteristic obtained in step d) is a characteristic automatically selected by the software used, which may be different in different current images from different cameras. Accordingly, step e) must be performed for each new current image from a camera. This automatic selection of geometric characteristics has the advantage that the current two-dimensional deflection and rotation of the geometric characteristics relative to their idle position can always be correctly determined, even when lighting conditions and occlusion change. In the event of a failure of the load receiver, it can be simply replaced with a new load receiver, regardless of whether the new load receiver has the same design as the old one, because the geometric characteristics are not fixed but are always automatically reselected repeatedly when the method is executed. In this case, only the idle position image needs to be re-recorded once.

[0011] According to one embodiment of the invention, the determination of the current deflection and rotation of the load receiving device in step f) is carried out by digital image processing, which has an advantage in terms of processing speed.

[0012] Preferably, steps c) and f) are repeated multiple times at closely spaced time intervals, and the motion period of the load receiving device is determined based on the continuous current deflection and rotation of the load receiving device. Vibration damping can be optimally adjusted based on this motion period.

[0013] According to one embodiment of the method of the present invention, based on the current deflection and rotation of the load receiving device determined in step f), a control command is generated in the evaluation unit and transmitted to the vibration damping system acting on the load receiving device, and then the vibration damping system is controlled based on the control command.

[0014] In addition, to achieve the above objectives, the present invention also provides a system comprising a camera, particularly a digital camera, and an evaluation unit designed to perform the method according to the present invention.

[0015] Advantageously, the system also includes a vibration damping system.

[0016] In addition, to achieve the above objectives, the present invention also provides a lifting device having a hoisting vehicle and a load receiving device disposed on the hoisting vehicle. The lifting device further includes: a camera disposed on the bottom surface of the hoisting vehicle and oriented such that it acquires the top surface of the load receiving device; an evaluation unit designed to perform the method according to any one of the claims; and a vibration damping system acting on the load receiving device, the vibration damping system being controlled by the evaluation unit. Attached Figure Description

[0017] Other features and advantages of the invention will become clearer from the following description and with reference to the accompanying drawings. In the drawings, Figure 1 A schematic side view of a lifting device according to an embodiment of the present invention is shown, and Figure 2 Show Figure 1 A schematic plan view of the load receiving device of the lifting equipment. Detailed Implementation

[0018] Figure 1 A lifting device 1 is shown, comprising a trolley 2 movable by a motor in the X and Y directions, and a load receiving device 4 suspended from the trolley by a motor-driven load-bearing rope 3 movable in the Z direction. As an example only, the load receiving device 4 could be a device designed to accommodate containers for commercial sale.

[0019] To implement the method according to an embodiment of the invention for two-dimensionally determining the current deflection and rotation of a load receiving device 4 supported on a crane 2 relative to its idle position, in a first step, a camera 5 is positioned on the crane 2 such that the camera acquires an image of the top surface of the load receiving device 4, as shown by the dashed line 6 in the figure. In this example, the camera 5 is a conventional digital video camera. Furthermore, in this example, an evaluation unit 7 and a vibration damping system 8 are also provided on the crane 2. However, the evaluation unit 7 and the vibration damping system 8 can also be arranged in other locations and / or integrated into existing components of the lifting equipment 1.

[0020] In another step, the camera 5 records an image of the top surface of the load receiving device 4 in its idle position, and stores the idle position image in the evaluation unit 7.

[0021] During subsequent operation of the lifting equipment 1, camera 5 records a current image of the top surface of the load receiving device 4 and transmits it to evaluation unit 7. Then, in evaluation unit 7, geometric features 9, 10, and 11 that exist on the top surface of the load receiving device 4 and are unique to the load receiving device 4 are automatically selected from each current image from the camera. These geometric features 9, 10, and 11 are then searched in the idle position image. By comparing the positions of geometric features 9, 10, and 11 in the current image with their positions in the idle position image, the current two-dimensional (or equivalent) position of geometric features 9, 10, and 11 relative to their idle position is determined. Figure 1 The XY plane in the image is deflected and rotated. Based on the current deflection and rotation, the evaluation unit 7 generates signals for controlling the vibration damping system 8 and transmits these signals to the vibration damping system 8. The more current images of the camera are recorded and evaluated in the manner described above during a predetermined time period, the more accurate the motion period of the load receiving device 4, determined based on the continuous current deflection and rotation of the load receiving device 4, thereby enabling optimized vibration damping.

[0022] The main advantage of the aforementioned method is that its implementation requires only a few components: a camera 5, an evaluation unit 7, and a vibration damping system 8. No additional components, such as reflectors or infrared illumination units, are needed, thus achieving a very low-cost construction scheme.

[0023] For each current image from a camera, geometric properties 9, 10, and 11 are automatically redefined. Accordingly, the geometric properties of different current images from different cameras can differ from one another. The advantage of this is that even when lighting conditions and occlusion conditions change, the current two-dimensional deflection and rotation of the geometric properties relative to their free positions can be accurately determined.

[0024] In the event of a malfunction in load receiver 4, it can be simply replaced with a new one without subsequent recalibration of geometric features 9, 10, and 11. If a new load receiver with a different design than the old one 4 is chosen, only the new idle position image needs to be recorded and stored. Furthermore, the camera data stream recorded by camera 5 can also be used by the crane operator or a remote operator, which is another advantage.

[0025] According to an alternative implementation of the aforementioned method, the features 9, 10, and 11 acquired in the current image of the camera can be predefined features. Accordingly, these features 9, 10, and 11 only need to be searched once in the image of the idle location and subsequently stored, because these features remain unchanged.

[0026] Although the present invention has been illustrated and described in detail through preferred embodiments, the present invention is not limited to the disclosed examples, and those skilled in the art can derive other variations therefrom without departing from the protection scope of the present invention.

[0027] Regardless of the part of speech used, terms include masculine, feminine, or other parts of speech.

Claims

1. A method for two-dimensionally determining a current deflection and rotation of a load-receiving device (4) relative to a rest position of the load-receiving device (4), the load-receiving device being supported on a trolley (2) of a hoisting apparatus (1), the method having the following steps: a) arranging a camera (5) on the trolley (2) such that the camera (5) acquires an image of a top surface of the load-receiving device (4); b) recording an image of the top surface of the load-receiving device (4) in the rest position of the load-receiving device (4) and storing a rest position image; c) recording a current image of the top surface of the load-receiving device (4) when the load-receiving device (4) is not in the rest position during operation of the hoisting apparatus (1); d) acquiring a plurality of geometric features (9, 10, 11) present on the top surface of the load-receiving device (4) and specific to the load-receiving device (4) in the camera current image recorded in step c); e) searching for the geometric features (9, 10, 11) acquired in step d) in the rest position image; and f) determining a current two-dimensional deflection and rotation of the geometric features (9, 10, 11) relative to the rest position of the geometric features 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. The features (9, 10, 11) acquired in step d) are predefined features. The features (9, 10, 11) acquired in step d) are automatically selected features. The determination of the current deflection and rotation of the load-receiving device (4) in step f) is carried out by digital image processing. Steps c) and f) are repeated a plurality of times at closely spaced time intervals, and a motion cycle of the load-receiving device (4) is determined on the basis of successive current deflections and rotations of the load-receiving device (4). On the basis of the current deflection and rotation of the load-receiving device (4) determined in step f), control commands are generated in an evaluation unit (7) and transmitted to a vibration damping system (8) acting on the load-receiving device (4), which then controls the vibration damping system on the basis of the control commands.

7. A system comprising a camera (5), in particular a digital camera, and an evaluation unit (7) designed to carry out the method according to any one of the preceding claims.

2. The method of claim 1, wherein, 8. The system according to claim 7, further comprising a vibration damping system (8).

3. The method of claim 1, wherein, a camera (5) arranged at a bottom surface of the trolley (2), the camera being oriented such that it acquires an image of a top surface of the load-receiving device (4); an evaluation unit (7) designed to carry out the method according to any one of claims 1 to 6; and a vibration damping system (5) acting on the load-receiving device (4), which is controlled by the evaluation unit (7).

4. The method according to any of the preceding claims, characterized in that, ​ 5. The method according to any of the preceding claims, characterized in that, ​ 6. The method according to any of the preceding claims, characterized in that, ​ ​ ​ 9. A hoisting device (1) having a trolley (2) and a load receiving arrangement (4) arranged on the trolley (2), the hoisting device comprising: ​

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