EP2931649B1 - Rotating tower crane - Google Patents

Description

The present invention relates to a crane, in particular a tower crane, with a crane boom rotatable about an upright axis, on which a trolley is movably arranged, from which a lifting cable connected to a load hook runs, and a load hook position determining device for determining the load hook position.

A crane with a load hook position determining device, for example, the font shows WO 91/14644 A1 ,

Tower cranes may have an at least approximately crane jib which is carried by a tower which extends upright and can be turned around the upright longitudinal axis of the tower. In the case of a so-called head turner, the boom rotates relative to the tower, while in the case of a bottom turner, the entire tower and thus the arm articulated thereon are rotated. The distance of the load hook from the tower axis can be adjusted by means of a trolley, which is movable along the boom, wherein the lifting cable connected to the load hook runs over the said trolley.

For various reasons, it is desirable in this case to determine the exact position of the load hook via a corresponding load hook position determination device as accurately as possible. This can not only be beneficial if the load hook For example, behind a wall for the crane operator is no longer visible, but also when the trolley position no longer coincides exactly with the hook position, that is no longer congruent in the vertical direction (it is understood that the vertical position of load hook by the lowering depth of the load hook and trolley deviates). Such a deviation of the load hook position from the trolley position can have different causes, for example, an odd course of the hoisting rope or dynamic deflections such as pendulum movements of the load or wind deflections. Depending on the task to be accomplished, it may be sufficient to determine the hook position only relative to the trolley or crane, for example, to dampen oscillations, or it may also be an absolute load hook position required in the room, for example, an automated operation at Umschlagvorgängen realize. Apart from such uses of the load hook position signal for control purposes, increased safety can also be achieved by determining the load hook position, since the load can be permanently monitored, whereby possibly a redundancy of the lowering depth sensor can also be achieved.

It is known from the prior art to optically detect the load hook position. For example, the shows JP 9-142773 a crane, on whose jib tip from which the hoist rope runs, a down-facing camera is mounted, the viewing direction is adjusted to follow pendulum movements of the load hook, so that the crane operator can always see the load hook on the camera. The DE 197 25 315 C2 describes a metallurgical crane with a relative to a support frame movable trolley from which runs the hoist. On the support frame several cameras are arranged, the field of view is large enough to detect the crane hook at different Katzfahrwerkstellungen. In such a metallurgical crane, the positions to be approached are relatively rigid, so that the amount of image data to be processed remains manageable. If such a system were used in a tower crane, however, a flood of data that could hardly be processed would come about.

From the Scriptures WO 2005/082770 A1 Furthermore, a tower crane is known, on the trolley, a downward-facing camera is mounted to the crane operator to display a video image of the load hook environment, so that the crane operator can better detect obstacles lying in the direction of movement. This camera system is used to visualize obstacles or the settling or receiving area, which the crane operator has to control, but it is not the load hook position relative to the crane or determined absolutely in space.

The DE 41 90 587 C2 describes a shipping container crane in which a load hook position is determined by means of a camera which is attached to the suspension device for the crane rope. In this case, several upwardly radiating light sources are attached to the recorded containers, which are detected by the camera. However, this is not readily possible with cranes such as tower cranes, which also accommodate loads such as construction site products, which are often significantly smaller than containers, since the large-area container top is not available here.

Similarly, with light sources works the DE 102 45 970 A1 , in which the load is additionally irradiated from above by means of a light source. The other light source mounted on the load to be picked up sends a light signal only up to the suspension device - as an optical echo, so to speak - when the load from the upper light source is irradiated.

The US 6,351,720 B1 shows finally a container crane, in which the load position is determined by means of several cameras, one of which is attached to a trolley of the crane and another on the portal of the crane to account for twisting of the crane can. However, this entails a very complicated data processing, moreover, there is a problem that the second camera has obstacles and the like has an impaired field of view.

The present invention is based on the object to provide an improved tower crane of the type mentioned, the disadvantages of the prior art avoids and the latter develops in an advantageous manner. In particular, an improved position determination of the load hook is to be achieved, which manages with a limited amount of data processing and thus limited computer capacity, but it determines the position without excessive time delay exactly.

According to the invention, said object is achieved by a tower crane according to claim 1. Preferred embodiments of the invention are the subject of the dependent claims.

It is therefore proposed optically to determine the hook position by means of a camera which is mounted on the trolley of the crane and looks down from the trolley in a predetermined and thus known viewing direction down to the load hook. The position of the load hook in the camera image is determined by an image evaluation unit. From the position of the load hook in the camera image and the trolley position, evaluation means then determine the actual load hook position. According to the invention, the image evaluation unit has contour recognition means for recognizing an outline contour corresponding to the load hook and / or attached attachment in the camera image, wherein the load hook position is determined on the basis of the outline contour of the load hook and / or the attached attachment. The invention is based on the consideration that at a predetermined viewing direction of the camera attached to the trolley corresponds to the position of the load hook in the camera image of the load hook position relative to the trolley or a measure of the load hook position relative to the trolley and thus with complementary attraction of the trolley position the absolute position of the load hook in space can be determined. If the camera looks exactly vertically downwards from the trolley, the position of the load hook in the camera image or the position deviation of the load hook from the center of the camera balance is a measure for the transverse offset or horizontal offset of the load hook relative to the trolley, said horizontal offset of the load hook relative to the trolley, taking into account the respective depression depth of the load hook, ie the distance of the load hook from the trolley and an optionally adjusted zoom factor of the camera can be determined. Advantageously, no multiple cameras or images from different visual axes are needed, since the position determination can be done with only one camera or out of just one camera image, thereby saving considerable computing power.

The distance of the load hook from the trolley can be determined in various ways. On the one hand, the sink depth of the load hook can be determined from the unwound Hubseillänge, even with not exactly straight Hubseilverlauf a sufficiently accurate measure of the distance of the load hook from the trolley or camera mounted therein, to the said distance of the load hook from the trolley and to determine the actual relative position or the actual horizontal offset of the load hook relative to the trolley, the image position of the load hook or the offset of the load hook from the image center determined in the camera image.

Alternatively or additionally, the distance of the load hook from the trolley or the camera attached thereto can also be determined from the camera image itself, in particular by means of an image evaluation unit, the number of pixels of the image representation of the load hook and / or an associated attachment such as a Seilumlenkflasche or a another crane structure part, which is located in the vicinity of the load hook as intended, or also an associated marking and / or the size of the load hook or said attachment of said mark in the camera image. Given a known size of the load hook or known size of the attachment or the marking, the distance of the crane hook or the attachment or the mark can be determined very accurately from the camera zoom factor and the number of pixels and / or the display size in the camera image. The determination of the load hook distance from the trolley by means of pixel counting can be carried out in addition to the alternative lowering depth determination, for example from the hoist rope spool length, in order to achieve a redundant system for the lowering depth determination of the load hook and thus increase safety. Optionally, however, the optical determination by means of pixel evaluation can also be provided as an alternative.

The identification of the load hook in the camera image provided by the camera can basically be done in various ways, for example by pixel evaluation and / or contour evaluation and / or color evaluation. Especially For example, a pixel pattern that corresponds to the load hook and / or the attached attachment such as rope bottle or special mark, as well as the outline contour and color of the load hook and / or the associated attachment can be determined. In this case, known image processing algorithms such as binary imaging, edge detection or feature selection can be used to analyze the camera image. In order to increase the probability of detection or to simplify the identification of the crane hook or the marking applied thereto, the provided image can also be subjected to a spectral analysis, wherein, for example, reflection properties can be analyzed.

In order to simplify finding the load hook in the camera image, the image evaluation unit may comprise cable course determination means for determining the cable course of the hoist cable running from the trolley. The running of the trolley hoist has in the camera image provided usually a very characteristic contour in the form of a very narrow, long straight line or a very slightly curved, long, narrow line whose starting point by the deflection of the trolley in the camera image in a relatively narrow area and thus can be easily identified. In particular, the hoisting rope running off the trolley in the case of the usually provided shearing on the load hook or the associated load bottle in the camera image produces two acute-angled or conically converging lines, in whose connection point at least approximately the position of the load hook can be assumed.

The position to be determined for the position of the load hook can in principle be provided in various ways, advantageously an absolute coordinate position indication can be done in an absolute coordinate system, which may for example have its origin in the foot of the crane, for example, the tower longitudinal axis Z axis, the boom can describe the X axis and a vertical axis can describe the Y axis. The image evaluation unit can be the image position of the load hook in the camera image determine first in a relative coordinate system, for example, a trolley coordinate system, which has its origin in the camera and / or the trolley and is aligned parallel to the aforementioned absolute coordinate system, but the Z-axis corresponding to the optical axis of the camera inverse to Z Axis of the absolute system can run. Position information in this relative coordinate system, which can be displaced by trolley movements, are then converted by the position determination means, taking into account the trolley position in position information in the abovementioned absolute coordinate system.

In order to simplify the image analysis and reduce the amount of data can be arranged in a further development of the invention on the load hook or the associated load bottle, by means of which the hoist rope is deflected on the load hook, a mark of predetermined size and / or predetermined contouring on an upper side attached to the load hook or the load bottle and / or visibly facing the trolley or camera attached thereto. Said marking can in this case be formed as a separate component, for example in the form of a plate attached to the top of the bottle or a target, such a separate component can be mounted or attached to the load hook or the associated load bottle, for example, welded or screwed can.

As an alternative or in addition to such a separate marking part, the load hook and / or the load bottle itself may also be designed as a marking, for example by corresponding contouring of a load hook and / or load bottle section visible towards the trolley, in which case, for example, the load hook with its top-side head section is an example angular or circular contour, for example in the form of a mushroom-shaped or collar-shaped, in plan view triangular widening can be contoured.

As a marker, in this case, for example, a ring arrangement in the manner of a target or other geometric base contour or base such as triangle, quadrangle or polygon, circle, oval or ellipse, straight or curved lines or hybrids or combinations thereof, the marker may advantageously be composed of contrasting surface pieces, such as a white circle with a black dot in its center , and / or strong, from the usual ambient colors different colorations may have, for example, luminous color dots to facilitate the identification of the marker in the camera image.

In order to be able to determine not only the position but also the orientation of the marking in the camera image, it is advantageously possible to use a marking deviating from rotationally symmetrical shapes, in particular clearly oriented marking contours, for example in the form of a "T" or an isosceles, not equilateral Triangles or the like. When using such markings not only the exact position of the load hook, but also a rotation relative to the boom alignment can be determined by the image evaluation unit and corresponding evaluation of the camera image, which can occur, for example, by rotation of the load hook hanging on the load hook.

In addition, especially in difficult installation conditions for separately mounted marker on the crane hook of the visible hook can be used as a marker, for example in the aforementioned manner by special contouring of the trolley facing head section. This can be done on the basis of face recognition, as used in surveillance systems. In this case, suitable geometric features of the crane hook can be used as markers or markers. This has the advantage that separate marker attachments are unnecessary, which can be damaged or contaminated during operation. An advantage of the development is that only a certain number of predetermined features must be visible. Even with a partial covering of individual features of the crane hook is still reliably detected in its position and orientation.

In order to keep the data processing volume as small as possible in the image evaluation, the image area to be evaluated and / or the size of the image to be evaluated can be variably controlled in dependence on various operating parameters in an advantageous development of the invention. A camera control unit can in particular adjust the zoom factor of the camera as a function of the lowering depth of the load hook, wherein the lowering depth determined from the hoist rope length can be used here for example for a presetting of the zoom factor and / or an adjustment or readjustment of the zoom factor after distance determination by pixel counting and / or determining the image representation size as explained above. In particular, with increasing lowering depth or increasing distance of the load hook from the trolley, the zoom factor can be increased in order to achieve a certain size of the representation of the crane hook or the associated mark in the camera image. It considerably facilitates the identification of the marking or of the load hook in the camera image if the image evaluation unit knows, at least approximately, in advance how large the pixel pattern to be identified is in the overall image or what proportion of area the image representation of the marking or the load hook makes in the overall image.

Alternatively or additionally, the said zoom factor can also be varied by the camera control device as a function of other variables, in particular as a function of the result of an image evaluation attempt. If the load hook or the associated marking can not be identified in the image at a previously set zoom factor, the zoom factor can be reduced in order to be able to search a larger area of the image. If necessary, the zoom factor can be iteratively reduced several times in order to scan larger and larger areas in several stages. Alternatively or additionally, however, the zoom factor can also be increased if the load hook or the associated mark could not be identified in a camera image, which may possibly also be due to the fact that the load hook is much too small in the picture when the zoom factor is very high so that the image sharpness or pixel count is not sufficient to identify the known contour pattern of the marking and / or the load hook and / or the load bottle.

As an alternative or in addition to such an adjustment of the zoom factor of the camera, the camera control device and / or the image evaluation unit can also vary an area to be evaluated within the camera image provided by the camera in order to minimize the amount of data to be evaluated. The image section of interest can be enlarged, in particular, if the marking or the load hook has been lost in the previously evaluated image detail, for example, because the load hook has moved out of the image section due to stronger oscillations or stronger wind load. If the marking or the load hook is lost in the image detail examined by the image evaluation unit, said image detail can be inflated once or iteratively in several stages, if appropriate, until it covers the entire camera image. Advantageously, the image evaluation unit can be designed in such a way that only the added image section area is re-evaluated when enlarging the image section of interest or to be evaluated, for example the frame-shaped image sectioning part which has been added by enlarging the image section around the previous image section.

As an alternative or in addition to such a one-time or iterative enlargement of the image section which is evaluated by the image evaluation unit in order to identify the position of the load hook or the marking attached thereto, if the load hook or the associated marking can be identified in the camera image, the image section in the provided camera image is shifted and / or reduced, preferably in such a way that the new image section to be examined is centered with respect to the identified position of the load hook or the associated marking, ie the identified marking lies in the middle of the new image section. Alternatively or additionally, the image section can be reduced once or iteratively, in particular in such a way that the pixel pattern reproducing the marking or the load hook is reduced or the corresponding image contour pattern represents a predetermined area proportion of the respective image detail, for example representing 20% of the area of the image detail used for the evaluation.

The position of the load hook can advantageously be determined not only relative to the trolley of the crane, but also absolutely and / or relative to the load hook environment, for example the construction site environment, from the camera image. In a further development of the invention, the position determination device can have environmental determination means for determining the load hook environment, in particular in the form of characteristic obstacle and / or environmental contours, from the recorded camera image, wherein the position determination means for determining the load hook position from the determined image position of the load hook in the camera image may be formed such that the load hook position is determined relative to the load hook environment.

The load hook position relative to the environment, which can be determined from the camera image in the above-mentioned manner, can advantageously be determined to control the crane movements, in particular to approach a load hook target, for example a settling or pickup position, or to stop crane movements or a travel path of the car Automatically change load hook to avoid a collision of the load hook and / or a load taken with an identified in the camera image obstacle such as building edge. The crane may have load hook control means for controlling crane movements depending on the particular load hook position relative to the load hook environment and / or collision avoidance control means for stopping or changing crane movements depending on the particular load hook position relative to the load hook environment.

Fig. 1:

eine schematische Darstellung eines Turmdrehkrans, an dessen Ausleger eine verfahrbare Laufkatze vorgesehen ist, von der das mit einem Lasthaken verbundene Hubseil abläuft und an der eine Kamera zur Positionsbestimmung des Lasthakens angeordnet ist,

Fig. 2:

eine vergrößerte, ausschnittsweise Darstellung der am Ausleger vorgesehenen Laufkatze und der mit der Kamera verbundenen Systemkomponenten für die Bildübertragung und -auswertung sowie Positionsbestimmung,

Fig. 3:

eine Darstellung einer an der Oberseite der mit dem Lasthaken verbundenen Lastflasche angebrachten Markierung, die in dem von der Kamera bereitgestellten Kamerabild identifizierbar ist,

Fig. 4:

eine Darstellung einer Markierung ähnlich Fig. 3, wobei die Markierung im Gegensatz zur Fig. 3 eine eindeutige Orientierung aufweist, um zusätzlich zur Position auch die Orientierung bzw. Drehstellung des Lasthakens bestimmen zu können, und

Fig. 5:

ein von der Kamera bereitgestelltes Kamerabild des Lasthakens, wobei der im Kamerabild dargestellte Hubseilverlauf zu sehen ist, aus dem ebenfalls die Lasthakenposition bestimmt werden kann und/oder die Identifizierung des Lasthakens oder der damit verbundenen Markierung im Kamerabild vereinfacht werden kann.

The invention will be explained in more detail below with reference to a preferred embodiment and associated drawings. In the drawings show:

Fig. 1:

a schematic representation of a tower crane, on the boom of a movable trolley is provided, from which runs the associated with a load hook hoist and on which a camera for determining the position of the load hook is arranged

Fig. 2:

an enlarged, fragmentary representation of the trolley provided on the boom and connected to the camera system components for image transmission and evaluation and position determination,

3:

a representation of a mounted on the top of the load hook connected to the load hook mark that is identifiable in the camera image provided by the camera,

4:

a representation of a mark similar Fig. 3 , where the mark in contrast to Fig. 3 has a unique orientation, in addition to the position to be able to determine the orientation or rotational position of the load hook, and

Fig. 5:

a camera image of the load hook provided by the camera, wherein the Hubseilverlauf shown in the camera image can be seen, from which also the load hook position can be determined and / or the identification of the load hook or the associated mark in the camera image can be simplified.

As Fig. 1 shows the crane can be designed as a tower tower crane rotating above 1, the tower 2 extending upright carries a boom 3 and a counter-jib. Said boom 3 can be rotated relative to the tower 2 about the upright longitudinal axis of the tower 4 and assume an at least approximately horizontal position. At the said boom 3, a trolley 5 is movably suspended, so that the trolley 5 can be moved substantially over the entire length of the boom 3 to the discharge of the load hook 7 vary. The said load hook 7 is fastened to a hoist rope 6, which runs over said trolley 5 in order to be able to lower and lift the load hook 7. In a manner known per se, a load bottle 13 can be provided on the load hook 7, cf. Fig. 2 over which the hoist rope 6 is deflected or sheared on the load hook 7.

As Fig. 2 1, a load hook position determining device 8 comprises a camera 9 mounted on the trolley 5, which is movable together with the trolley 5 and looks downwards from the trolley 5 substantially vertically. As Fig. 2 shows, the viewing axis of the camera 9 can move together with the Z-axis of the local or relative Katzkoordinatensystems.

The image data provided by the camera 9 can advantageously be transmitted by a cordless transmission device 19, for example in the form of a radio transmission device, to an image processing and evaluation system 20, which can advantageously be arranged in the area of the driver's cab or crane control unit, and a corresponding receiver / transmitter unit 21a which can communicate with the reception / transmission unit 21b of the transmission device 18 on the trolley. Basically, the image evaluation could be done directly on the camera 9 and the trolley 5, but it is preferred to collect there only the image data and then transfer it and evaluate elsewhere to make the system in the trolley small and easy to be able to train.

To supply the camera 9 with energy, an energy storage 22, for example in the form of a battery can be provided on the trolley 5, which can be loaded by means of a charging station 23, which can be arranged on the boom 3, for example in the parking position of the trolley 5 to to load the energy storage 22 in out-of-service times of the crane.

The image processing and evaluation system 20 may comprise a central computer 24, for example in the form of an industrial PC with an image processing system, which can be connected via a video server 25 with the receiving / transmitting device 21, on the one hand to receive or retrieve the image signals of the camera 9 and on the other hand to be able to send control signals to the camera 9.

As Fig. 2 shows, may advantageously be provided in the area of the crane driver's station and a video display 26 in order to be able to display the image of the camera 9 to the crane operator in addition to determining the position.

In order that the image evaluation unit 11 implemented in the computer 24 can detect and identify the load hook 7 in the camera image provided by the camera 9, features of the load hook 7 and / or the associated load bottle 13 are advantageously defined in advance, for example geometric surfaces, shapes, contours, Colors and the like, wherein in an advantageous embodiment of the invention, a marker 14 on the upper side of the load hook 7 and the load bottle 13 can be mounted so that the mark 14 for the camera 9 is visible.

As Fig. 3 shows, the mark 14 may be in the manner of a target of contrasting rings, which are set in one another. As an alternative to such a rotationally symmetric marking, however, it is also advantageously possible to use a uniquely oriented marking 14, as it does Fig. 4 shows, for example in the form of a "T", which also here again advantageously a high-contrast representation is used. However, it should be understood that instead of such a "T", the marker 14 may also have other orientation determination features, for example, two or more rotationally symmetric markers may be provided in geometric relation to each other, and / or other orientation oriented rectangular marker shapes may be used find and / or geometric shapes of the load itself or the load bearing such as the spreader container crane can be used as a marker.

The camera 9 is advantageously controlled via control signals from the image processing and evaluation system 20, the control signals here as well about the in Fig. 2 shown radio link can be transmitted. In this case, the image evaluation unit 11 attempts to discover the load or the load hook 7 on the basis of the predefined marking 14 within the image provided by the camera 9. An analysis of the provided camera image can be carried out by various algorithms such as a binary image, an edge detection and / or a feature selection.

With the aid of the update rate of the camera images provided by the camera 9 and the associated evaluation rate of the image evaluation unit 11, the load hook 7 or the load located thereon can be determined not only statically in the image, but also during dynamic movements of the load. Here, a tracking of the load, a so-called tracking done.

In order to support the identification of the marking 14 in the camera image, the lowering depth of the load hook 7 can preferably be permanently provided by the crane control, on the basis of which at least approximately it can be estimated at which distance the load hook 7 from the camera 9 is located. Thereupon, the image processing and evaluation system 20 adjusts the camera zoom of the camera 9 accordingly.

The analysis of the respectively provided camera image can be carried out continuously, preferably by means of edge detection, binary image generation and feature selection with respect to the known mark 14. In this case, the processing is advantageously carried out within a predefinable image detail in a specific region of the camera image. Since the size, depending on the operating case can be kept very small, the computational effort is thereby considerably reduced. In this case, the image section can be selected to be minimally so small that it essentially corresponds to the marker size. Alternatively or additionally, the image detail to be analyzed can at most correspond substantially to the entire size of the complete camera image.

The position and / or size of said image detail may be determined based on the last known marker positions and an estimated prediction. For this purpose, for example, a so-called Kalman filter or other filter devices can be used, which can make a prediction on the basis of the past values.

As far as no past marker positions are available for a prediction during the initialization of the image processing, the image section to be examined can be arbitrarily placed in the image. Should no mark be found in this image section, the image section can be continuously increased until the marker 14 is within the image section and can be detected.

As soon as the marking 14 can be detected in the camera image, the image evaluation unit 11 determines the image position of the load hook 7 or the mark 14 in the camera image, from which the position determining means 12 then determine the load hook position in the relative coordinate system of the trolley 5. Said relative Katzkoordinatensystem can be chosen so that it has its origin in the optical axis of the camera 9 and the zero point of the sinking depth, which may be in the trolley 5.

On the basis of the known size of the mark 14, the currently set zoom factor of the camera 9 as well as the number of pixels of the mark 14 in the camera image measured by the sensor, an exact distance determination of the mark 14 can be made by the trolley 5. From this, the Z-offset or the Z-difference of the load hook 7 can be determined to the sinking depth, which sinking depth can be determined for example by determining the unwound Hubseillänge. By separately measuring the actual sink depth over the pixel size of the marker 14 in the camera image, a redundancy to the conventional Senektiefesensor can be achieved.

Since in real use the load is never really at rest due to crane movements, wind influences or the dynamics of the crane, the load oscillates, the pendulum frequency being dependent on the rope length of the hoist rope 6. The pendulum amplitude depends on the mass and other factors such as the dynamics of movement or the wind input.

In order to improve the detection probability for the detection of the mark 14 in the camera image in the image analysis, an estimate can also be made here where the load hook 7 is likely to be in subsequent measurements, whereby the aforementioned Kalman filter can also be used here.

If the marking 14 moves out of the camera image due to a too large pendulum amplitude, the image evaluation device may lose the marking 14. To detect the marking 14 as quickly as possible, the following procedure can be adopted:
First of all, for example, the image detail of the camera image to be analyzed can be inflated or enlarged and / or shifted onto an image section by expecting the reentry of the marking 14. Alternatively or additionally, the entire camera image can also be defined as an image detail, in particular if the available computing power is sufficiently large.

Alternatively or in addition to such a change in the image section, after a loss of the mark 14, the camera 9 can also zoom back one or more stages in order to enlarge the image area. Due to the thus enlarged image area, there is a high probability that the marker will be within the image again. In order to compensate for the disadvantages of the resulting smaller marking size, the zoom factor of the camera 9 can be iteratively increased in several steps and also reduced again.

As an alternative or in addition to the aforementioned image processing strategies, the image evaluation unit 11 may comprise cable course determination means 17 by means of which the course of the hoisting rope 6 is determined in the camera image, as this Fig. 5 shows. Based on the detected Hubseilverlaufs in the camera image, the position of the load hook 7 can be determined or at least the area are narrowed, in which the load hook 9 and the marker 14 must lie, so that said Hubseil-course determination as an alternative or in addition to the detection of said marker or of the load hook 7 can be provided directly from the camera image.

The determination of the hook position or narrowing of the area in which the load hook must be 7, using the Rope course determination is based on the assumption that the hoist rope 6 in a reeving on the load bottle 13 in the camera image has a conical shape, in particular conically to the load runs, cf. Fig. 5 so that the load hook 7 or the load and their position can be determined as the end of the cone defined by the hoist rope sections.

In order to increase the probability of detection with respect to the areas and contours of interest in the camera image, the measured image can also be subjected to a spectral analysis in a development of the invention. In this case, for example, the reflection properties of the features of the load, the load hook 7 or the marking 14 in certain spectral regions can expand the feature space and be used for the identification.

Such an approach can be part of a pre-filtering of the image, which significantly reduces the quantity of image data to be examined with the aid of the algorithms mentioned. This significantly reduces the effort of the algorithms for detecting the hook position. Even adverse weather conditions such as snow, ice, rain, fog, sunlight, shadows, etc. can be at least partially compensated.

Such a spectral analysis can be advantageously optimized by the use of special lacquers for the marking 14, for example by the Use of paints or other surface coatings that have low reflective properties in the near infrared range.

For said prefiltering, e.g. a known Landsat algorithm can be used.

Claims (14)

1. Crane, in particular tower slewing crane, having a jib (3) rotatable about an upright axis (4), at which jib a trolley (5) is movably arranged, from which trolley a hoist rope (6) connected to a load hook (7) runs off, as well as a load hook position determining device (8) for determining the load hook position, wherein the load hook position determining device (8) comprises a camera (9) arranged at the trolley (5) and oriented downward towards the load hook (7) in a predetermined viewing direction (10), an image evaluator (11) for determining the image position of the load hook (7) in a camera image provided by the camera (9), as well as position determining means (12) for determining the load hook position based on the determined image position of the load hook (7) in the camera image while taking into account a position of the trolley, characterized in that the image evaluator (11) has contour recognition means for recognizing, in the camera image, an outer contour corresponding to the load hook and/or its attachment, and the load hook position is determined based on the outer contour of the load hook and/or the attachment mounted thereto
2. Crane according to the preceding claim, wherein the image evaluator (11) includes rope run determining means (17) for determining the hoist rope run in the camera image, and the image evaluator (11) is adapted such that the position of the load hook (7) in the camera image is determined in dependency of the determined hoist rope run, wherein the load hook position is determined as being the point of intersection of two hoist rope lines identified in the camera image.
3. Crane according to any one of the preceding claims, wherein the load hook position determining device (8) comprises distance determining means for determining the distance of the load hook (7) from the trolley (5), wherein said distance determining means has a pixel counter for determining the number of pixels of the load hooks and/or marker image area identified in the camera image.
4. Crane according to any one of the preceding claims, wherein a lowering depth determining means is provided for determining the lowering depth of the load hook (7) based on an unwound length of the hoist rope (6).
5. Crane according to one of claims 3 or 4, wherein a horizontal displacement of the load hook (7) in relation to the trolley (5) is determinable by the position determining means (12) based on the determined image position of the load hook (7) in the camera image taking into account the respective set zoom ratio of the camera and the determined lowering depth/distance of the load hook (7) from the trolley (5).
6. Crane according to any one of the preceding claims, wherein a camera control device for controlling camera settings is provided and adapted such that the zoom ratio of the camera (9) is set variably in dependency of a load hook lowering depth.
7. Crane according to the preceding claim, wherein the camera control device (15) is adapted such that the zoom ratio of the camera (9) is increased and/or decreased in dependence on recognition of the load hook (7) and/or the marker (14) provided thereon in the camera image provided by the camera (9), in particular such that when the load hook (7) and/or the marker (14) associated therewith is not recognized the zoom ratio is decreased once or iteratively.
8. Crane according to any one of the preceding claims, wherein the image evaluator (11) includes image section control means (16) for enlarging an image section of the camera image to be evaluated by the image evaluator (11), which enlarging is effected in dependence on recognition of the load hook (7) and/or the marker (14) associated therewith, wherein said image section control means (16) are adapted such that in the case of non-recognition of the load hook (7) and/or the marker (14) associated therewith, starting with a small image section, such image section is enlarged once or iteratively.
9. Crane according to any one of the preceding claims, wherein the image evaluator (11) includes pixel evaluation means for recognizing a pixel pattern corresponding to the load hook and/or an attachment connected thereto such as a pulley, as well as color recognition means for recognizing, in the camera image, a color and/or color combination corresponding to the color and/or color combination of the load hook and/or the attachment thereof.
10. Crane according to any one of the preceding claims, wherein a marker (14) is attached to the load hook (7) and/or a pulley (13) connected thereto which marker is visibly oriented towards the trolley (5), and the image evaluator (11) is adapted such that in the camera image a contour and/or pixel pattern corresponding to the marker is identified.
11. Crane according to the preceding claim, wherein the marker (14) and/or the load hook and/or the pulley includes a geometrical base such as circle, polygon, line and/or a base pattern combined of several geometrical bases.
12. Crane according to any one of the two preceding claims, wherein the marker (14) and/or the load hook and/or the pulley are adapted in an unambiguously oriented manner and the image evaluator (11) has orientation determining means for determining the orientation of the load hook (7), in particular determining a rotation angle of the load hook (7) in relation to an upright axis.
13. Crane according to any one of the preceding claims, wherein trolley position determining means (18) are provided which trolley position determining means include travel position determining means for determining the trolley position relative to the jib and slewing position determining means for determining the slewing position of the jib (3) relative to the rotational axis (4), wherein the load hook position determining means (12) are adapted such that the load hook position is determined based on the determined trolley position relative to the jib (3), the slewing position of the jib (3) and the image position of the load hook (7) in the camera image of camera (9).
14. Crane according to any one of the preceding claims, wherein the position determining device (8) includes neighborhood determining means for determining the load hook neighborhood, in particular in terms of characteristic obstacle and/or neighborhood contours, based on the taken camera image, wherein the position determining means (12) for determining the load hook position based on the determined image position of the load hook (7) in the camera image are adapted such that the load hook position is determined relative to the load hook neighborhood, wherein load hook target control means are provided for controlling crane movements in dependency of the determined load hook position relative to the load hook neighborhood and/or collision prevention control means for stopping or altering crane movements in dependency of the determined load hook position relative to the load hook neighborhood.

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