Control System and Method of Landing an End Portion of a Freely Projecting Elongated Element, and Use of an Image Processor for Generating of Control Parameters for the Control System

Abstract

A control system and a method are for maneuvering an elongated element which projects in a pivotable manner from a foundation. The landing place is provided with a camera-readable pattern. The projecting end portion is provided with at least one camera which is arranged to imagine the graphic pattern when the end portion is near the landing place. The camera is connected in a signal-communicating manner to an image processor. The image processor is arranged to determine the position of the camera relative to the pattern by an image analysis and convert the image information into control parameters for the control system to position the projecting end portion relative to the landing place.

Claims

1. A control system for maneuvering an elongated element which projects in a pivotable manner from a foundation and which is arranged to position a projecting end portion relative to a landing place remote from the foundation, the maneuvering being provided by one or more actuators connected to the control system, wherein: the landing place is provided with a camera-readable pattern; the projecting end portion is provided with at least one camera which is arranged to image the graphic pattern when said end portion is near the landing place; the at least one camera is connected in a signal-communicating manner to an image processor; and the image processor is arranged to determine the position of the at least one camera relative to the pattern by image analysis and convert the image information into control parameters for the control system to position the projecting end portion relative to the landing place.

2. The control system according to claim 1, wherein the projecting end portion is provided with at least two cameras which are arranged in a spaced-apart manner and are unidirectional and have coinciding camera planes.

3. The control system according to claim 1, wherein the projecting end portion includes a landing gear which is at least partially inside the field of view of the at least one camera.

4. The control system according to claim 1, wherein the elongated element is a gangway, and wherein the projecting end portion is arranged to land on the landing place.

5. A method of manoeuvring maneuvering an elongated element which projects in a pivotable manner from a foundation and is arranged to position a projecting end portion relative to a landing place remote from the foundation, the method comprising: maneuvering the element by several actuators connected to a control system, providing the landing place with a camera-readable pattern; providing the projecting end portion with at least one camera which is arranged to image the pattern when said end portion is near the landing place; connecting the at least one camera in a signal-communicating manner to an image processor; by an image analysis in the image processor, determining the position of the at least one camera relative to the pattern and converting the image information into control parameters for the control system; and positioning the projecting end portion relative to the landing place.

6. The method according to claim 5, further comprising: continuously updating the control parameters.

7. The method according to claim 5, further comprising: performing a landing of the projecting end portion, or an element suspended from the projecting end portion, at the landing place, automatically by a continuous updating of the control parameters for the control system.

8. (canceled)

9. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In what follows, an example of a preferred embodiment is described, which is visualized in the accompanying drawings, in which:

[0038] FIG. 1 shows, in perspective, an elongated element in the form of a gangway which is provided, in an outer end portion, with a landing gear and a camera rig including two cameras, the outer end portion of the gangway being positioned over a landing place provided with a camera-readable pattern in the form of equally spaced graphic objects;

[0039] FIG. 2a shows a front view of the outer end portion with the landing gear and the camera rig;

[0040] FIG. 2b shows a side view of the outer end portion with the landing gear and the camera rig;

[0041] FIGS. 3a and 3b show the landing place seen from the first camera (FIG. 3a) and a second camera (FIG. 3b) with lens axes perpendicular to the landing place and an image base line parallel to a side edge of the landing place;

[0042] FIG. 4 shows an image composed of images from the first and second cameras represented in FIGS. 3a and 3b, the imaged distance between identical objects being indicated;

[0043] FIG. 5 shows the landing place seen from the first camera when a lens axis is perpendicular to the landing place and the image base line has been rotated relative to the landing place; and

[0044] FIG. 6 shows the landing place seen from the first camera when a lens axis is oblique to the landing place and the image base line is parallel to a side edge of the landing place.

DETAILED DESCRIPTION OF THE DRAWINGS

[0045] Reference is first made to FIG. 1, in which an elongated element 1, shown as a gangway here, projects from a foundation 13 which may be arranged on a vessel or a fixed installation (not shown), a first end portion 11 being supported around first and second rotary axes 131 and 132, respectively, and being telescopically extendable in order to, by means of actuators 14, be able to land a second, outer end portion 12 on a landing place 2 on an installation not shown, for example a vessel or a fixed installation at sea. The outer end portion 12 is appropriately provided with a landing gear 15, shown here as a conical element rotatably supported in a ball joint 151 in the outer end portion 12 and arranged to be securable to structures at the landing place 2 when the gangway 1 has landed in a preferred position indicated by a landing mark 23 in FIG. 1. A control system 16 is connected to several actuators 14 and a drive not shown, for example a hydraulic system including motor(s), pumps, valves, accumulators, hoses and pipes for the controlled supply of a pressurized fluid to the actuators.

[0046] Reference is now made to FIGS. 2a and 2b in particular. In the immediate vicinity of the attachment of the landing gear 15 to the gangway 1, a camera assembly 3 is arranged, in which first and second cameras 31, 32 are arranged to image at least a lower portion 152 of the landing gear 15 and an area located below the landing gear 15. The cameras 31, 32 are set with lens axes 34, 34′ parallel to each other and coinciding camera planes 33, 33′ and image bases 35, 35′ (see FIGS. 3a and 3b) and are preferably arranged with the image bases 35, 35′, that is to say one image edge of the image, perpendicular to the longitudinal axis of the gangway 1. A camera field of view 36 is indicated in FIG. 1.

[0047] Reference is now made to FIGS. 3a and 3b in particular. The landing place 2, which is provided with an access 21, for example a gate, is provided with a camera-readable pattern 22 comprising one object 221.

[0048] Cameras that are sensitive to light of different wavelengths from those of visible light may be used.

[0049] When the landing place 2 is identified by means of the graphic pattern 22 imaged by both cameras, illustrated by the representations according to FIGS. 3a and 3b, the images are paired into a combined image as is shown in FIG. 4, and the distance L.sub.a read between the representations of the graphic object 221 can be used together with the known distance between the cameras 31, 32 in the camera rig 3 to calculate the distance from the camera plane 33 to the landing place 2.

[0050] These calculations are carried out by an image processor 161 and are converted into control parameters for the control system 16 for the actuators 14 of the gangway 1. By a continuous processing of the image information, the control system 16 can be constantly updated with new control parameters until the gangway 1 has landed at the landing place 2.

[0051] By calculating the imaged spacing of three objects 221a, 221b, 221c which are arranged in an equally spaced manner in the pattern 22 at the landing place 2, as is shown in FIGS. 5 and 6, the image analysis may also, in addition to giving information about the distance between the gangway 1 and the landing place 2, give information, about the angling of the gangway 1 relative to the landing place 2.

[0052] FIG. 5 shows a situation imaged by the first camera 31, in which the lens axis 34 is perpendicular to the landing place 2, but the camera 31 has been rotated so that the image base line 35 is not parallel to a front (represented as the bottom) side edge 2a of the landing place 2. The imaged distance L.sub.v can be used as an indicator of the rotation, by comparison with the imaged distance L.sub.2, among other things.

[0053] FIG. 6 shows a situation imaged by the first camera 31, in which the lens axis 34 is at an angle, whereas the image base line 35 is parallel to the front side edge 2a of the landing place 2. Among other things, the relationship between the imaged distances L.sub.1 and L.sub.2 can be used as an indicator of the slant of the lens axis 34.

[0054] The analytical result of a set of images can also be checked, be verified, that is, by comparing the result with analytical results from earlier stages in the ongoing landing operation.

[0055] The control parameters that are generated by the image analyses can be used for automatically manoeuvring the elongated element 1, especially in critical stages as during landing of the projecting end portion 12 of a gangway at the landing place 2, but also of other elongated, projecting elements, for example a crane boom.

[0056] It should be noted that all the above-mentioned embodiments illustrate the invention, but do not limit it, and persons skilled in the art may construct many alternative embodiments without departing from the scope of the dependent claims. In the claims, references in brackets are not to be regarded as restrictive. The use of the verb “to comprise” and its different forms, does not exclude the presence of elements or steps that are not mentioned in the claims. The indefinite article “a” or .sup.“an.sup.” before an element does not exclude the presence of several such elements.

[0057] The fact that some features are stated in mutually different dependent claims does not indicate that a combination of these features cannot be used with advantage.