Tower slewing crane

Abstract

The present invention relates to a crane, having a jib rotatable about an upright axis, at which jib a trolley is movably arranged, from which trolley a hoist rope connected to a load hook runs off, as well as a load hook position determining device for determining the position of the load hook. The load hook position may be determined optically by means of one camera only, which camera is mounted on the trolley of the crane and views from the trolley in a predetermined and thus known viewing direction downwards onto the load hook. In doing so, the position of the load hook in the camera image is determined by an image evaluator. To simplify detection of the load hook in the camera image, the image evaluator may include rope run determining means for determining the rope run of the hoist rope running off from the trolley.

Claims

1. A crane, in particular a tower slewing cranecomprising: a jib rotatable about an upright axis, at which jib a trolley is movably arranged, from which trolley a hoist rope connected to a load hook runs off, as well as a load hook position determining device for determining a load hook position, wherein the load hook position determining device comprises a camera arranged at the trolley and oriented downward towards the load hook in a predetermined viewing direction, an image data processing and evaluation system comprising a processor, an image evaluator carried out in the processor for determining an image position of the load hook in a camera image provided by the camera via at least one of pixel evaluation, contour evaluation, and color evaluation, and position determining means carried out in the processor for determining the load hook position based on the determined image position of the load hook in the camera image while taking into account a position of the trolley and providing a load hook position signal.

2. The crane according to claim 1, wherein the image evaluator includes rope run determining means for determining a hoist rope run in the camera image, and the image evaluator is adapted such that the position of the load hook in the camera image is determined in dependency of the determined hoist rope run.

3. The crane according to claim 1, wherein the image evaluator is adapted such that the load hook position is determined as being a point of intersection of two hoist rope lines identified in the camera image.

4. The crane according to claim 1, wherein the load hook position determining device comprises distance determining means for determining a distance of the load hook from the trolley, wherein said distance determining means has a pixel counter for determining a number of pixels of an image area of the load hook and/or a marker identified in the camera image.

5. The crane according to claim 4, wherein a lowering depth determining means is provided for determining a lowering depth of the load hook based on an unwound length of the hoist rope.

6. The crane according to claim 5, wherein a horizontal displacement of the load hook in relation to the trolley is determinable by the position determining means based on the determined image position of the load hook in the camera image taking into account a respective set zoom ratio of the camera and the determined lowering depth/distance of the load hook from the trolley.

7. The crane according to claim 6, wherein a camera control device for controlling camera settings is provided and adapted such that the zoom ratio of the camera is set variably in dependency of the load hook lowering depth.

8. The crane according to claim 7, wherein the camera control device is adapted such that the zoom ratio of the camera is increased and/or decreased in dependence on recognition of the load hook and/or the marker provided thereon in the camera image provided by the camera, in particular such that when the load hook and/or the marker associated therewith is not recognized, the zoom ratio is decreased once or iteratively.

9. The crane according to claim 4, wherein the image evaluator includes image section control means for enlarging an image section of the camera image to be evaluated by the image evaluator, which enlarging is effected in dependence on recognition of the load hook and/or the marker associated therewith, wherein said image section control means are adapted such that in the case of non-recognition of the load hook and/or the marker associated therewith, starting with a small image section, such image section is enlarged once or iteratively.

10. The crane according to claim 9, wherein the image evaluator 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 a color and/or color combination of the load hook and/or the attachment thereof.

11. The crane according to claim 10, wherein the image evaluator 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.

12. The crane according to claim 1, wherein a marker is attached to the load hook and/or a pulley connected thereto which marker is visibly oriented towards the trolley, and the image evaluator is adapted such that in the camera image a contour and/or pixel pattern corresponding to the marker is identified.

13. The crane according to claim 12, wherein the marker and/or the load hook and/or the pulley includes a geometrical base such as a circle, a polygon, a line and/or a base pattern combined of several geometrical bases.

14. The crane according to claim 12, wherein the marker and/or the load hook and/or the pulley are adapted in an unambiguously oriented manner and the image evaluator has orientation determining means for determining an orientation of the load hook, in particular determining a rotation angle of the load hook in relation to the upright axis.

15. The crane according to claim 1, wherein trolley position determining means are provided, which trolley position determining means include travel position determining means for determining a trolley position relative to the jib and slewing position determining means for determining a slewing position of the jib relative to the upright axis, wherein the upright axis is a rotational axis, wherein the load hook position determining means are adapted such that the load hook position is determined based on the determined trolley position relative to the jib, the slewing position of the jib and the image position of the load hook in the camera image of the camera.

16. The crane according to claim 1, wherein the load hook position determining device includes neighborhood determining means for determining a load hook neighborhood, in particular in terms of characteristic obstacle and/or neighborhood contours, based on the camera image, wherein the position determining means for determining the load hook position based on the determined image position of the load hook in the camera image are adapted such that the load hook position is determined relative to the load hook neighborhood.

17. The crane according to claim 16, 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.

18. A crane, in particular a tower slewing crane, comprising: a jib rotatable about an upright axis, at which jib a trolley is movably arranged, from which trolley a hoist rope connected to a load hook runs off, as well as a load hook position determining device for determining a load hook position, wherein the load hook position determining device comprises a camera arranged at the trolley and oriented downward towards the load hook in a predetermined viewing direction, an image data processing and evaluation system comprising a processor, an image evaluator carried out in the processor for determining an image position of the load hook in a camera image provided by the camera, and position determining means carried out in the processor for determining the load hook position based on the determined image position of the load hook in the camera image while taking into account a position of the trolley and providing a load hook position signal, wherein the image evaluator has contour recognition means for recognizing, in the camera image, an outer contour corresponding to the load hook and/or its attachment, and wherein the load hook position is determined based on the outer contour of the load hook and/or the attachment mounted thereto.

19. A crane, in particular a tower slewing crane, comprising: a jib rotatable about an upright axis, at which jib a trolley is movably arranged, from which trolley a hoist rope connected to a load hook runs off, as well as a load hook position determining device for determining a load hook position, wherein the load hook position determining device comprises a camera arranged at the trolley and oriented downward towards the load hook in a predetermined viewing direction, an image data processing and evaluation system comprising a processor, an image evaluator carried out in the processor for determining an image position of the load hook in a camera image provided by the camera, and position determining means carried out in the processor for determining the load hook position based on the determined image position of the load hook in the camera image while taking into account a position of the trolley and providing a load hook position signal, wherein the image evaluator is adapted such that the load hook position is determined as being a point of intersection of two hoist rope lines identified in the camera image.

20. The crane according to claim 1, wherein the determination of the load hook position is effected based on one camera only and/or based on one camera image only.

Description

BRIEF DESCRIPTION OF FIGURES

(1) FIG. 1: a schematic representation of a tower slewing crane at the jib of which a movable trolley is provided from which trolley a hoist rope connected to the load hook runs off and at which trolley a camera for determining the position of the load hook is arranged,

(2) FIG. 2: an enlarged, partial representation of the trolley provided at the jib and of the system components for image transfer and evaluation as well as position determination, which system components are associated with the camera,

(3) FIG. 3: a representation of a marker provided on the top face of the pulley connected to the load hook, which marker is identifiable in the camera image provided by the camera,

(4) FIG. 4: a representation of a marker similar to FIG. 3, wherein the marker, contrary to FIG. 3, is unambiguously oriented so as to allow, in addition to determination of the position, also allow determination of the orientation and/or rotatory position of the load hook, and

(5) FIG. 5: a camera image provided by the camera and showing the load hook, wherein the hoist rope run represented in the camera image is shown, from which hoist rope run the load hook position may also be determined and/or by means of which identification of the load hook or the marker associated therewith in the camera image may be simplified.

DETAILED DESCRIPTION

(6) As is shown by FIG. 1, the crane may be adapted to be a top-slewing tower slewing crane 1 the uprightly extending tower 2 of which carries a jib 3 as well as a counter-jib. Said jib 3 may be rotated relative to tower 2 about the tower's upright longitudinal axis 4 and may assume an at least approximately horizontal position. A trolley 5 is movably suspended from said jib 3, so that the trolley 5 may be moved substantially along the entire length of jib 3 so as to be able to vary the working radius of load hook 7. Said load hook 7 is in this context fixed to a hoist rope 6 running off via said trolley 5 so as to be able to lower and lift load hook 7. In a manner known per se, a pulley 13 may be provided at the load hook 7, cf. FIG. 2, via which pulley the hoist rope 6 is diverted and/or reeved at the load hook 7.

(7) As is shown by FIG. 2, a load hook position determining device 8 comprises a camera 9 mounted at the trolley 5, which camera is, together with trolley 5, movable and views basically vertically downwards from trolley 5. As is shown by FIG. 2, the visual axis of camera 9 and the Z-axis of the local and/or relative trolley coordinate system can be coaxial to each other.

(8) The image data provided by camera 9 may advantageously be transferred to a data processing and evaluation system 20 by a wirelessly working transfer means 19, e.g. in the form of a wireless transmission device, which may advantageously be arranged in the area of the operator's cab or the crane control unit and which may comprise an according transceiver unit 21a that may communicate with the transceiver unit 21b of the transfer means 18 at the trolley. Basically, data evaluation could be effected directly at the camera 9 and/or the trolley 5, image data is, however, preferably only collected there and then transferred and evaluated at a different place so as to be able to build the system in the area of the trolley in a small and lightweight manner.

(9) In order to provide camera 9 with power, an energy store 22 such as, e.g., in the form of an accumulator may be provided at the trolley 5, which energy store may be charged by means of a charging station 23 which may be arranged at the jib 3 for example in the area of a parking position of trolley 5 so as to be able to charge energy store 22 during out of operation periods of the crane.

(10) The data processing and evaluation system 20 may comprise a central processor 24 for example in the form of an industrial personal computer having an image processing system, which processor may be connected to the transceiver 21 via a video server 25 so as to receive and/or retrieve the image signals of camera 9 on the one hand, and to be able to send control signals to camera 9 on the other hand.

(11) As is shown by FIG. 2, also a video display 26 may advantageously be provided in the area of the crane operator's cab, so as to be able to display to the crane operator, in addition to the determination of the position, also the image of camera 9.

(12) In order for the image evaluator 11, which is carried out in processor 24, to be able to detect and identify load hook 7 in the camera image provided by camera 9, characteristics of load hook 7 and/or pulley 13 connected thereto are advantageously previously defined, for example geometrical areas, shapes, contours, colors and the like, wherein, in an advantageous further development of the invention, a marker 14 may be provided at the top face of load hook 7 and/or pulley 13 so that the marker 14 is visible to the camera 9.

(13) As is shown by FIG. 3, the marker 14 may, similar to a sight disk, consist of rings rich in contrast to each other and placed into each other. In the alternative to such rotation-symmetric marking, however, advantageously also an unambiguously oriented marker 14 as shown in FIG. 4 may be used, for example in the shape of a “T”, a high-contrast representation advantageously being used in this case as well. It goes without saying, however, that instead of such “T”, the marker 14 as well may also have other characteristics for determining the orientation, for example two or more rotation-symmetric markers in geometric relation to each other may be provided, and/or other rectangular marking forms related to orientation may be used and/or geometric shapes of the load itself or of the load pick up device such as the spreader of a container crane may be used as marker.

(14) Camera 9 is advantageously controlled by the image processing and evaluation system 20 by means of control signals, wherein said control signals may in this context also be transferred via the radio circuit shown in FIG. 2. The image evaluator 11 attempts, based on the predefined marker 14, to detect the load and/or the load hook 7 within the image provided by camera 9. An analysis of the camera image provided may in this context be effected by means of a plurality of algorithms such as, e.g., a binary image creation, an edge detection and/or selection of a characteristic.

(15) Based on the updating rate of the camera images provided by camera 9 and based on the evaluation rate of image evaluator 11 connected thereto, the load hook 7 and/or the load located thereon may be determined not only statically in the image, but also in the case of dynamic movements of the load. In this context, tracing of the load, so-called tracking, may be effected.

(16) In order to support identification of marker 14 in the camera image, the lowering depth of load hook 7 may advantageously be permanently provided by the crane control, on the basis of which lowering depth it can at least approximately be estimated at which distance from camera 9 the load hook 7 is positioned. The image processing and evaluation system 20 then sets the camera ratio of camera 9 accordingly.

(17) Analysis of the respective camera image provided may be effected continuously, preferably by means of edge detection, binary image generation and selection of characteristics in respect of the known marker 14. In this context, processing is carried through advantageously within a predeterminable image section in a determined region of the camera image. Since the size, depending on the operational case, may be kept very small, computing effort is hereby considerably minimized. The image section may in this context be chosen to be minimally that small that it basically corresponds to the size of the marker. In the alternative or in addition, the image section to be analyzed may maximally correspond basically to the entire size of the complete camera image.

(18) The position and/or the size of said image section may be determined on the basis of the last known marker positions and an estimated prognosis. For this purpose, for example a so-called Kalman filter or also other filtering facilities which may make a prognosis based on past values may be used.

(19) In so far as at the time of initialization of image processing no past marker positions are available for a prognosis, the image section to be examined may be laid into the image arbitrarily. If no marking is found in this image section, the image section may continuously be expanded, until marker 14 lies within the image section and may be detected.

(20) As soon as marker 14 may be detected in the camera image, the image evaluator 11 determines the image position of load hook 7 and/or of marker 14 in the camera image, on the basis of which the position determining means 12 then determine the load hook position in the relative coordinate system of trolley 5. Said relative trolley coordinate system may be chosen such that it has its origin in the optical axis of camera 9 and the zero point of the lowering depth which may lie in the trolley 5.

(21) On the basis of the known size of marker 14, the currently set zoom ratio of camera 9 as well as the number of pixels of marker 14 in the camera image, which number of pixels is measured by the sensor system, an exact distance determination of marker 14 from trolley 5 may be effected. Herefrom, the Z displacement and/or the Z difference of load hook 7 relative to the lowering depth may be determined, which lowering depth may be determined for example by determining the unwound hoist rope length. Due to the separate measurement of the actual lowering depth by means of the pixel size of marker 14 in the camera image, redundancy of the conventional lowering depth sensor may be achieved.

(22) Since in real use the load is never really at rest due to crane movements, the influence of wind or the dynamics of the crane, the load is swinging, wherein the pendulum frequency is dependent on the rope length of hoist rope 6. The pendulum amplitude is dependent on the mass and other factors such as movement dynamics or wind entry.

(23) In order to improve, during image evaluation, the detection probability of detecting marker 14 in the camera image, here as well an estimate may be effected as to where load hook 7 will presumably be during subsequent measurements, wherein here, too, the aforesaid Kalman filter may be employed.

(24) If marker 14 moves out of the camera image due to a too large pendulum amplitude, the image evaluator may lose marker 14. In order to detect marker 14 again as fast as possible, one may proceed as follows:

(25) At first, the camera image's image section to be analyzed may, for example, be inflated and/or expanded and/or shifted so as to become an image section in which re-entry of marker 14 is expected. In the alternative or in addition, also the entire camera image may be defined as image section, in particular if the available processing power is sufficiently large.

(26) In the alternative or in addition to such alteration of the image section, the camera 9 also may, after having lost marker 14, zoom back one or several steps so as to expand the image area. Based on an image area expanded in such a way, probability is high that the marker is positioned within the image again. In order to compensate the disadvantages of a hereby decreased marker size, the zoom ratio of camera 9 may be increased and also again decreased iteratively in a plurality of steps.

(27) In the alternative or in addition to the aforesaid image processing strategies, the image evaluator 11 may comprise rope run determining means 17, by means of which the run of the hoist rope 6 in the camera image is determined, as is shown by FIG. 5. Based on the detected hoist rope run in the camera image, the position of load hook 7 may be determined or at least the area in which load hook 9 and/or marker 14 must lie may be narrowed down, so that said hoist rope run determination may be provided in the alternative or in addition to detection of said marking and/or of load hook 7 directly from the camera image.

(28) Determination of the load hook position and/or narrowing down of the area in which load hook 7 must be, with the help of rope run determination is based on the assumption that hoist rope 6 possesses, when reeved at the pulley 13, a conical run in the camera image, in particular that it runs conically towards the load, cf. FIG. 5, so that load hook 7 and/or the load and its position may be determined as end of a cone defined by hoist rope sections.

(29) In order to heighten the detection probability regarding interesting areas and contours in the camera image, the measured image may, in a further development of the invention, also be subjected to a spectral analysis. In doing so, for example the reflective properties of the characteristics of the load, the load hook 7 or the marker 14 in determined spectral areas may broaden the range of characteristics and may be used for identification.

(30) Such a procedure may be part of a prefiltering of the image, which significantly reduces the amount of image data then to be examined with the help of the aforementioned algorithms. The algorithms' effort for the detection of the load hook position is thus decreased considerably. Even adverse climatic conditions such as snow, ice, rain, fog, sunlight, casting of shadows etc. may be compensated at least in part.

(31) Such a spectral analysis may advantageously also be optimized by the use of special lacquers for marker 14, for example by the use of lacquers or other surface coatings possessing only minor reflective properties in the near-infrared range.

(32) For the aforementioned prefiltering, for example a Landsat algorithm known per se may be used.