Patent Grant
9340263
This application is the National Stage of International Application No. PCT/NL2009/000082, filed Apr. 3, 2009, the contents of which is incorporated by reference herein.
The present invention relates in general to a motion compensation device for compensating a carrier frame—which might for example carry a load transfer device, like a crane or gantry—on a vessel for local water motion.
More specifically, the present invention relates to a motion compensation device for compensating a carrier frame, on a vessel for local water motion wherein the device comprises:
The invention further relates to an assembly comprising such a motion compensation device according to the invention and a crane, which assembly might further comprise a vessel as well.
The invention further relates to an assembly comprising such a motion compensation device according to the invention and a vessel, which assembly preferably comprises a crane as well. Worded differently, the present invention thus also relates to a vessel provided with a motion compensation device according to the invention, which vessel preferably is provided with a crane as well.
When transferring loads from a vessel to another vessel or to some other construction, which might be movable or unmovable relative to the ground, problems arise due to movement of the water on which the vessel floats. Motion of the water subjects the load transfer device, and consequently the load to be transferred, to similar movements. In case the load is carried by a hoisting cable, the water motion will cause a swinging movement of the load as well. Similar problems arise when a vessel is receiving a load, like a helicopter landing on the vessel, a container or other load. Movement of the water causes the vessel to move, which in turn causes similar movement of the location on the vessel which is to receive the load.
Also when the weather conditions are very calm, the above mentioned problems due to local water movement are present. In this respect it is to be noted that although evidently the water is brought into motion strongly by wind, the effects of wind can lag for weeks in water and have influence on water at large distance away from the location of the wind. Even the water might look like very calm, but still being in motion due to wind weeks ago and/or far away. The effect of this on for example marine building operations is that one has to wait for the water to be almost motionless, in case for example a crane with hoisting cable is to be used safely.
With respect to the motions to which a vessel on water is subjected, it is to be noted that a vessel is in fact subject to 6 degrees of freedom of movement, three translational movements and three rotational movements. Using a mathematical approach based on a carthesian coordinate system having an imaginary set of three orthogonal axes—an x-axis, y-axis and z-axis—these 6 movements can be called x-axis translational movement, y-axis translational movement, z-axis translational movement, x-axis rotational movement, y-axis rotational movement and z-axis rotational movement. It is to be noted, that from a mathematical point of view there are also other equivalent manners to define the 6-degrees of movement in a space, for example the 3 axes used might not be orthogonal with respect to each other or a so called spherical coordinate system might be used. It is just a matter of mathematical calculation to transfer one definition of 6 degrees of freedom of movement into another definition of 6 degrees of freedom of movement. Using the so called carthesian coordinate system and defining the z-axis as extending vertically, the x-axis as extending in longitudinal direction of a vessel and the y-axis as extending in transverse direction of a vessel,
the x-axis translational movement is in practise called surge
the y-axis translational movement is in practise called sway
the z-axis translational movement is in practise called heave
the x-axis rotational movement is in practise called roll
the y-axis rotational movement is in practise called pitch
the z-axis rotational movement is in practise called yaw
GB 2.163.402 discloses an arrangement for open sea transfer of articles between two vessels, which arrangement uses a gantry—having two hingingly connected arms—mounted with one end of the gantry upon a vessel and carrying on the other free end of the gantry a carrying device in the form of a load platform. The load carrying device is space stabilised, it carries a stabilisation sensing arrangement which senses all three rotational and all three translational movements of the load carrying device in space and provides signals so that the gantry can be controlled by jacks and associated control means for compensation of all three rotational movements and all three rotational movements. This arrangement is complex in construction and unable to compensate for local water movements in case the load is carried by a hoisting cable. Also the control for compensation of 6 degrees of freedom of movement is complex. Further, taking into account that the load platform provided with the sensors is due to being carried by a hinging arm (the gantry) at a large distance from the vessel, the rotational movements of the vessel are first increased in magnitude by the arm length and afterwards compensated, which makes the control more difficult.
U.S. Pat. No. 5,947,740 discloses a simulator enabling an operator to reproduce or represent under test conditions phenomena likely to occur. This simulator comprises a platform carried by six+one hydraulic units. The lower ends of the six hydraulic units are fixed in pairs of two in a triangular pattern to the fixed world and the upper ends are fixed in different pairs of two to a simulation platform, also in a triangular pattern. In rest position all the six hydraulic units extend obliquely with respect to the vertical—none of the hydraulic units being parallel to each other in the rest position. These six hydraulic units are actively controlled to move the platform for simulation purposes. The other one hydraulic unit is a vertical one, which essentially carries the load of the platform and is passive, i.e. not controlled. Advantage of this passive central hydraulic unit is that the other six hydraulic units are just for control of movements of the platform and do not need to support the load of the platform. The forces to be exerted for control of the movement of this platform are thus reduced. Although the document does not appear to say so, this simulator is of the type which is used for flight simulators for training airplane pilots. It is known, that this simulator of U.S. Pat. No. 5,947,740 is also used to compensate a passenger transfer platform on a vessel against movement of the water, so that the passengers can walk easily to another vessel or a construction with fixed position without movement of the gangway. The difference between simulator and movement compensator application being essentially in the control. In the compensator application, the control is based on measurements of movement sensors to compensate the six degrees of freedom of movement of the platform for the measured movement. This compensator and its control system are relatively complex and consequently also expensive.
The present invention has as its object to provide motion compensation device for compensating a carrier frame on a vessel for local water motion, which is relatively simple in construction and control.
According to the invention this object is achieved by providing a motion compensation device for compensating a carrier frame on a vessel for local water motion, wherein the device comprises:
and/or
According to the invention the actuator system comprises at least three cylinder-piston-units, preferably hydraulic cylinder-piston-units, which are arranged essentially parallel, especially essentially vertical (i.e. in the z-axis direction). In use these cylinder-piston units can be extend or shortened simultaneously to adjust the vertical height—in z-axis direction—of the carrier frame with respect to the vessel. During use, when a vessel is essentially stationary on its place this is the dominant vessel movement to be compensated for when the vessel goes up and down with the—often relatively slow and long—wave movement of the water. The less dominant sideways roll of the vessel and aft-front pitch of the vessel are compensated for by adjusting the cylinder-piston-units differently with respect to each other. Although it is possible that the cylinder-piston-units are fixed with respect to each other in the sense that during use their relative positions remain unchanged—for example in case they are mutually perfect parallel they will always extend mutually parallel—, it is in practise more practical to allow them some freedom of rotational movement around the x-axis or y-axis, i.e. during use the longitudinal axis of said cylinder-piston-units undergo some movement relative to each other. Here a vertical longitudinal axis—of a said cylinder-piston-unit—is understood to comprise deviations of the longitudinal axis with respect to the vertical of less than 15°, preferably at most 10°, more preferably at most 5°. In rest position—defined as a position in which the carrier frame and base are parallel to each other—, the said piston-cylinder-units will however preferably be mutually parallel. In order to prevent jamming of the device due to the device being over-determined, the upper and/or lower support of each cylinder-piston-unit is/are arranged to allow for x-axis rotational movement and y-axis rotational movement. The constraining system restricts x-axis translational movement, y-axis translational movement and z-axis rotational movement of the carrier frame with respect to the base to movements necessary to allow for z-axis translational movement, x-axis rotational movement and y-axis rotational movement of the carrier frame with respect to the base by said actuator system. Advantages of the device according to the invention are that the control for compensational movements is less complicated—the piston-cylinder-units will essentially stay parallel which simplifies the control—; that three piston-cylinder-units are sufficient, although easily more, in rest position, essentially parallel piston-cylinder-units can be used as well, in case this might be practical for whatever reason, without the control becoming much more complicated; and that relatively little space is needed in order to allow compensational movements of the support frame because the piston-cylinder-units stay essentially parallel during use (with a system like in U.S. Pat. No. 5,947,740 all space below the platform is required to be free from obstacles in order to allow the piston-cylinder-units to move between different slanting positions).
The concept behind this invention is that in most cases, it suffices to compensate only for z-axis translational movement, x-axis rotational movement and y-axis rotational movement of the vessel. The other three degrees of freedom of movement of the vessel (i.e. the z-axis rotational movement, the x-axis translational movement and the y-axis translational movement) need not be compensated for because they are under many circumstances negligible. These other three degrees of freedom of movements being negligible can have different reasons. When the carrier frame is, for example, a landing platform for a helicopter or a receiving platform for a load, these other degrees of freedom of movement might not play a role at all. When, for example, the vessel is anchored and/or kept in position by a dynamic positioning control, these other degrees of freedom of movement are already being taken care of.
In order to assist the carrier platform in reassuming its rest position, it is advantageous when the constraining system is resilient, i.e. comprises some resilient properties. In order to prevent oscillation due to the set back forces exerted by the resilient constraining system, it is according to the invention advantageous when the resilient constraining system is a damped resilient constraining system.
In order to arrange the upper and/or lower support of each cylinder-piston-unit to allow for x-axis rotational movement and y-axis rotational movement, it is according to the invention advantageous when the upper respectively lower support comprises one of the group of: cardan joint, spherical bearing or ball hinge. A cardan joint has two mutually transverse hinges, both transverse to the longitudinal axis of the joint, which hinges provide for the freedom for x-axis and y-axis rotational movement. This freedom for x-axis and y-axis rotational movement can also be achieved with a ball hinge or a spherical bearing. In general, the degree of freedom achievable with a spherical bearing is less than with a ball hinge. But, taking into account that the required degree of freedom is in many applications relatively small, a spherical bearing is in many applications satisfactory.
According to a further embodiment, the constraining system comprises:
at least one column fixed to said base and extending in the direction of the z-axis; and
for each column at least three guiding wheels which are swivelling suspended to the carrier frame to swivel around a swivel axis perpendicular to the z-axis, said at least three guiding wheels being arranged distributed around said column for riding along the length of said column, wherein a spring pretensions each guiding wheel to be swiveled against said column.
The column serves as guide to guide movement of the carrier frame in z-axis direction. When the carrier frame moves in z-axis direction, the guiding wheels will ride along the column. In order to allow the carrier frame to move with respect to the column in a direction transverse to the z-axis, the guiding wheels are suspended to the carrier frame in swivelling manner. The springs provide for a set back force which tends to restore the rest position. Although one said column could suffice, it is, with this embodiment, for smooth guidance advantageous to have a said column for each cylinder-piston-unit. In order to protect the cylinder-piston-units against damage from the surrounding, it is, with this embodiment, according to the invention advantageous when each said cylinder-piston-unit extends through said column. In order to obtain good guidance on the one hand and good set back towards the rest position on the other hand, it is, with this embodiment, according to the invention advantageous when four said guiding wheels are arranged around each said column, which guiding wheels are interspaced at 90° around the column. For damping action, it is according to the invention advantageous when the springs are provided with a damper for damping the spring action.
According to another embodiment, it is according to the invention advantageous when the constraining system comprises at least three bars, each bar being attached to the base with one end and to the carrier frame with the other end. These bars function in their longitudinal direction as essentially rigid push-pull-elements. The ends of these bars might be hingedly attached to the carrier frame and base, for example by means of a cardan joint. In case the attachment of the ends of the bars is constrained against z-axis rotation, the ends of a bar are movable with respect to each other by deflection.
For load spreading purposes and easy installing the device according to the invention on a vessel, it is according to the invention advantageous when the base comprises a separate base segment for each cylinder-piston-unit. A separate base segment for each cylinder-piston-unit provides sufficient spread of load as well as it allows easy and wobble-free placement of the device on a non-even deck or other surface of the vessel.
For easy transportation of the device according to the invention, such as transportation over sea, road or rail, it is advantageous when each separate base segment has outer dimensions corresponding to the outer dimensions of a standard sea container, preferably a 20, 30 or 40 feet container.
For easy transportation of the device according to the invention, it is further advantageous when each cylinder-piston-unit is hingedly mounted to either the carrier frame or the base for storing the cylinder-piston-unit with its longitudinal direction extending transverse, preferably perpendicular, to the z-axis. This allows a compact storage position.
According to the invention, it is further advantageous when:
A device with this maximum stroke for the cylinder-piston-units and/or this largest distance between two said cylinder-piston-units, is on the one hand relatively compact and on the other hand suitable for use in most near shore applications and/or applications under calm weather conditions.
According to a further aspect, the invention relates to an assembly comprising: a device according to the invention; and a crane. The crane can comprise a hoisting cable or a gripper which is hinged to a crane arm. It is further advantageous when this assembly comprises a vessel.
According to another further aspect, the invention relates to an assembly comprising: a device according to the invention; and a vessel.
According to the invention, it is further advantageous when the vessel is provided with an anchoring system arranged for preventing the vessel from x-axis translational movement, y-axis translational movement and z-axis rotational movement; and/or when the vessel is provided with a dynamic positioning system arranged for preventing the vessel from x-axis translational movement, y-axis translational movement and z-axis rotational movement.
According to still another aspect, the invention relates to a method for compensating a carrier frame on a vessel for local water motion, wherein the carrier frame is supported by an actuator system comprising at least three cylinder-piston-units, each having a vertical longitudinal axis; wherein z-axis translational movement, x-axis rotational movement and y-axis rotational movement of the vessel are measured; and wherein the cylinder-piston-units are controlled by control signals generated in response to the measurements of said z-axis translational movement, x-axis rotational movement and y-axis rotational movement of the vessel. According to this method it is advantageous when a resilient constraining system generating reaction forces upon disturbance of said rest position counteracts disturbances of said rest position.
According to still another further aspect, the invention relates to a control system for performing the method according to the invention, which control system comprises an actuator system adapted for translating a carrier frame along a z-axis and rotating the carrier frame around an x-axis and an y-axis, wherein the x-axis, y-axis and z-axis define an imaginary set of orthogonal axes, the z-axis extending vertical; a sensor system for sensing z-axis translational movement, x-axis rotational movement and y-axis rotational movement of a vessel and generating sensor signals representing said sensed movements of the vessel; and wherein the control system is arranged for generating control signals for driving the actuator system in response to said sensor signals such that the position of the carrier frame is compensated for said sensed movements of the vessel.
The present invention will be explained further with reference to the enclosed drawings, in which:
As shown in
Referring to
As indicated with arrow 29, the cylinder-piston-units 4, 5, 6 can move along their longitudinal axis 14. When one cylinder-piston-unit is extended or shortened more than one or both others, the ball hinges 21 and cardan joints 16 allow the cylinder-piston-units 4, 5, 6 to be slanted slightly with respect to the z-axis. The angle α between the longitudinal axis 14 and z-axis can vary in a range of [0°, 10°], but a range of [0°, 5°] is in general sufficient.
In order to prevent the carrier frame from drifting away due to the freedom of rotational movements of the cylinder-piston-units 4, 5, 6, there is provided a constraining system which restricts x-axis translational movement, y-axis translational movement and z-axis rotational movement of the carrier frame 2 with respect to the base to movements necessary to allow for z-axis translational movement, x-axis rotational movement and y-axis rotational movement of the carrier frame 2 with respect to the base 17 by said actuator system. In the embodiment of
As can be seen in
In
In the embodiment of
The cylinder-piston-units 54, 55, 56, 57 can move along their longitudinal axes 64. When one cylinder-piston-unit is extended or shortened more than one or more of the others, the spherical bearings 71 and 72 allow the cylinder-piston-units 4, 5, 6 to be slanted slightly with respect to the z-axis. The angle α between the longitudinal axis 64 and z-axis can easily vary in a range of [0°, 10°], but a range of [0°, 5°] is in general sufficient.
In order to prevent the carrier frame 52 from drifting away due to the freedom of rotational movements of the cylinder-piston-units 54, 55, 56, 57, there is provided a constraining system, which is in this embodiment a resilient system comprising at least one—in this embodiment four—column 91 fixed to the base 67 and extending in the z-axis direction as well as for each column at least three guiding wheels 86.
The guiding wheels 86 are arranged spaced around the column with intervals of 120° in case of three wheels 86 and intervals of 90° in case of four wheels. Each wheel 86 is carried by a triangular member which swivels around pivot 89 with respect to the carrier frame 52. A spring 87 pretensions each wheel 86 against the column 91. Inside each spring 87 a damper (92) might be provided. In case a cylinder-piston-units assumes a slightly slanting position (α≠0°), one or more of the springs 87 are compressed and will develop in reaction a resilient reaction force counteracting the offset from the rest position (α=0°). When a cylinder-piston unit is extended or shortened, the wheels 86 will ride along the column 91. In this second embodiment there is provided a column around each cylinder-piston-unit.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/NL2009/000082 | 4/3/2009 | WO | 00 | 10/3/2011 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2010/114359 | 10/7/2010 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4564356 | Winfree | Jan 1986 | A |
| 4930435 | Newman | Jun 1990 | A |
| 5590618 | Marshall | Jan 1997 | A |
| 5947740 | Kim | Sep 1999 | A |
| 6059253 | Koutsky et al. | May 2000 | A |
| 6182596 | Johnson | Feb 2001 | B1 |
| 7152547 | Hovland | Dec 2006 | B1 |
| 20080041296 | Thompson et al. | Feb 2008 | A1 |
| Number | Date | Country |
|---|---|---|
| 2163402 | Feb 1986 | GB |
| 1027103 | Mar 2006 | NL |
| 2007120039 | Oct 2007 | WO |
| Entry |
|---|
| English Abstract for NL 1027103. |
| Stewart, D., “A Platform With Six Degrees of Freedom”, Proc Instn Mech Engrs, vol. 190, Pt 1, No. 15, pp. 371-386 (1965-66). |
| Number | Date | Country | |
|---|---|---|---|
| 20120024214 A1 | Feb 2012 | US |
