U.S. patent application number 14/760179 was filed with the patent office on 2015-12-03 for vessel, motion platform, control system and method for compensating motions of a vessel.
The applicant listed for this patent is AMPELMANN OPERATIONS B.V.. Invention is credited to Frederik Gerner, Arie Jan Gobel, David Julio Cerda Salzmann, Jan van der Tempel.
Application Number | 20150344110 14/760179 |
Document ID | / |
Family ID | 48539348 |
Filed Date | 2015-12-03 |
United States Patent
Application |
20150344110 |
Kind Code |
A1 |
van der Tempel; Jan ; et
al. |
December 3, 2015 |
Vessel, Motion Platform, Control System and Method for Compensating
Motions of a Vessel
Abstract
A vessel (1) including a motion platform (4), which platform
comprises: --at least one carrier (6) for bearing, moving and/or
transferring a load; --a gangway (16) provided with a first end
pivotably connected to the carrier and an opposite second end; --a
multiple number of first actuators (5a) for moving the carrier
relative to the vessel; --a control system (8) arranged for driving
the multiple number of first actuators, wherein a cable (20)
extends from the vessel and/or the motion platform to at least a
position at or near the second end of the gangway.
Inventors: |
van der Tempel; Jan; (Delft,
NL) ; Gerner; Frederik; (Delft, NL) ;
Salzmann; David Julio Cerda; (Delft, NL) ; Gobel;
Arie Jan; (Delft, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AMPELMANN OPERATIONS B.V. |
Delft |
|
NL |
|
|
Family ID: |
48539348 |
Appl. No.: |
14/760179 |
Filed: |
January 9, 2014 |
PCT Filed: |
January 9, 2014 |
PCT NO: |
PCT/NL2014/050008 |
371 Date: |
July 9, 2015 |
Current U.S.
Class: |
114/230.2 ;
14/71.7 |
Current CPC
Class: |
B63B 2017/0072 20130101;
B63B 2027/141 20130101; B63B 27/30 20130101; B63B 27/14
20130101 |
International
Class: |
B63B 27/30 20060101
B63B027/30; B63B 27/14 20060101 B63B027/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 10, 2013 |
NL |
2010104 |
Claims
1. A vessel including a motion platform, which motion platform
comprises: at least one carrier for bearing, moving and/or
transferring a load; a gangway provided with a first end pivotably
connected to the carrier and an opposite second end; a multiple
number of first actuators for moving the carrier relative to the
vessel; a control system arranged for driving the multiple number
of first actuators, wherein a cable extends from the vessel and/or
the motion platform to at least a position at or near the second
end of the gangway.
2. The vessel according to claim 1, wherein the cable is connected
to the vessel or the motion platform by at least a winch.
3. The vessel according to claim 1, wherein the cable is provided
with a connecting element at an end opposite the vessel and/or
motion platform, for connecting to another vessel or structure.
4. The vessel according to claim 1, wherein at least one second
actuator is provided for moving the gangway relative to the
carrier, wherein the control system is also arranged for driving
the at least one second actuator.
5. The vessel according to claim 4, wherein the control system is
arranged for compensating a motion of the vessel in at least one
degree of freedom by driving the at least one second actuator.
6. The vessel according to claim 1, wherein at least one second
actuator is arranged for pivoting the gangway with respect to a
first pivoting axis substantially transverse with respect to a
longitudinal axis of the gangway.
7. The vessel according to claim 1, wherein at least one second
actuator is arranged for pivoting the gangway with respect to a
second pivoting axis substantially transverse with respect to the
carrier.
8. The vessel according to claim 1, wherein the first gangway end
is provided on a first gangway section, wherein the second gangway
end is provided on a second gangway section, and wherein at least
one second actuator is arranged for moving the second gangway
section with respect to the first gangway section substantially
along a gangway longitudinal axis.
9. The vessel according to claim 1, wherein the motion compensation
platform comprises a Stewart platform with at least one of
hydraulic, pneumatic or electric cylinders.
10. An assembly of a vessel according to claim 1 and a mooring
element, wherein the mooring element comprises a counter coupling
element for coupling to the cable and/or a coupling element
connected to the cable.
11. The assembly according to claim 10, wherein the mooring element
is provided with a receptacle for receiving the second end of the
gangway, within and/or over the receptacle.
12. The assembly according to claim 10, wherein the second end of
the gangway and the mooring element are configured such that the
mooring element can be carried by the gangway during movement
thereof relative to the vessel.
13. The assembly according to claim 10, wherein the mooring element
is provided with connecting elements for connecting the mooring
element to a vessel or structure.
14. A motion platform, for a vessel as described in claim 1, which
motion platform comprises at least one carrier for bearing, moving
and/or transferring a load, a gangway provided with a first end
pivotably connected to the carrier and a second end for contacting
a target area, a multiple number of first actuators for moving the
carrier relative to the vessel, at least a second actuator for
moving the gangway relative to the carrier, a control system
arranged for driving the multiple number of first actuators,
wherein the control system is also arranged for driving the at
least one second actuator, and wherein a cable is provided which is
or can be carried at or near the second end of the gangway.
15. A method for providing a gangway between a first vessel and
second vessel or a structure, wherein the gangway is carried at a
first end by a motion platform on the first vessel and has an
opposite second end, wherein further a cable is provided, connected
to the second vessel or structure, comprising the steps of: moving
the gangway by the motion platform in an active mode, such that the
second end is brought to a position near or in contact with the
second vessel or structure; connecting the cable to the second
vessel or structure; allowing the motion platform to follow the
movements of the first vessel relative to the movements of the
second vessel or structure, by bringing the platform from an active
mode into an inactive mode and/or allowing the gangway to follow
the movements of the first vessel relative to the movements of the
second vessel or structure, by bringing the gangway from an active
mode into an inactive mode.
16. The method according to claim 15, wherein the cable during
transfer to and/or from the second vessel or structure is carried
by the gangway and the cable is released from the gangway after
connecting the cable to the second vessel or structure, and is
pulled taut, before allowing the motion platform to follow the
relative movements.
17. The method according to claim 15, wherein the motion platform
is moved actively while moving the second end of the gangway to the
second vessel or structure, whereas the motion platform is allowed
to passively follow the relative movements of the vessel after
coupling the cable and/or the second end of the gangway to the
second vessel or structure.
18. The method according to claim 15, wherein the motion platform
is moved actively while moving the second end of the gangway to the
second vessel or structure, wherein the gangway is allowed to
passively follow the relative movements of the vessel after
coupling the cable and/or the second end of the gangway to the
second vessel or structure.
19. The method according to claim 15, wherein after coupling the
cable to the second vessel or structure, the cable is pulled taut,
wherein the second end of the gangway is pushed against the second
vessel or structure, at least partly by pushing a second part of
the gangway in a length direction of the gangway away from the
platform.
20. The vessel according to claim 1, wherein the cable is provided
with a connecting element at an end opposite the vessel and/or
motion platform, for connecting to another vessel or structure,
wherein the connecting element comprises at least a first prong for
hooking over an element connected to the gangway and at least a
second prong for hooking over a coupling element provided on the
other vessel or structure, and wherein the element connected to the
gangway is rod shaped and wherein the coupling element provided on
the other vessel or structure is rod shaped.
21. The method according to claim 15, wherein the cable is provided
with a connecting element at an end opposite the vessel and/or
motion platform, for connecting to another vessel or structure,
comprising the steps of: hooking at least a first prong of the
connecting element over an element connected to the gangway;
carrying the coupling element to a coupling element at the other
vessel or structure; hooking at least a second prong of the
connecting element over the said coupling element provided on the
other vessel or structure; releasing the first prong from the
element connected to the gangway; and moving a free end of the
gangway towards the other vessel or structure.
22. A motion platform for a an assembly according to claim 10,
which motion platform comprises at least one carrier for bearing,
moving and/or transferring a load, a gangway provided with a first
end pivotably connected to the carrier and a second end for
contacting a target area, a multiple number of first actuators for
moving the carrier relative to the vessel, at least a second
actuator for moving the gangway relative to the carrier, a control
system arranged for driving the multiple number of first actuators,
wherein the control system is also arranged for driving the at
least one second actuator, and wherein a cable is provided which is
or can be carried at or near the second end of the gangway.
Description
[0001] The invention relates to a vessel or an assembly for
transferring people and/or loads between a vessel and a second
vessel or structure. The invention further relates to a method for
providing a gangway between a vessel and a second vessel or
structure.
[0002] Such a vessel is e.g. known from the International patent
publication WO 2007/120039. The vessel is provided with a motion
platform which comprises a carrier borne by six hydraulic
cylinders, and a movable gangway connected to the carrier for
providing a connection between the carrier and another structure,
such as an offshore construction. During use, with the aid of
sensors, the motions of the respective vessel are measured. With
the aid of these measurements, the orientation of the hydraulic
cylinders is driven continuously so that the carrier remains
approximately stationary relative to the fixed world. In this
manner, motions of the ship are compensated so that a transfer
between the ship and the fixed world, or vice versa, is made
possible.
[0003] WO87/02723 discloses a vessel with an articulated ramp,
comprising a ramp section connected to a ship by means of a post,
extending perpendicular to and rotatable around a first axis
perpendicular to a deck of the ship and pivotable relative to said
post around a second axis perpendicular to said first axis. An
outer ramp section is connected to the first section by an
intermediate platform which is mechanically kept in a position
parallel to the ship's deck. The outer section can pivot relative
to the first section around a third axis parallel to the first axis
and a fourth axis perpendicular to said third axis. Actuators are
provided, by means of hydraulic cylinders, to move the first and
outer gangway sections relative to the ship and to an oil rig.
Anchor lines extend below the ramp sections, from a set of constant
tension winches in the post to a free end of the outer ramp
section. The anchor lines extend through a ball joint fixedly
connected to the outer ramp section by a rod, and through an anchor
line stop fitting. The oil rig is provided with a mooring station
for receiving the ball joint and the anchor line stop fitting, by
sliding the anchor lines between the ball joint and the stop
fitting into a slit in the mooring station and then pulling the
anchor lines tight, such that the ball joint is pulled against a
first side of the mooring station and the stop fitting to an
opposite side of the mooring station. In order to bring the stop
fitting with the anchor lines to the oil rig a pilot line is
connected to the ends of the anchor lines extending beyond the stop
fitting. The pilot line is then passed to the oil rig by a rig man
on the ship, which pilot man is received by a rig man on the oil
rig. The rig man on the oil rig then has to pull in the pilot line,
to slide the anchor lines in said slit. Then the winches are
activated for bringing the anchor lines under load and subsequently
pull the ball joint into a fixed connection with the mooring
station. In this known system there always has to be a rig man on
the oil rig for coupling and uncoupling. In coupled condition the
outer ramp section will rotate relative to the oil rig in six
degrees of freedom around the ball joint, whereas all forces for
maintaining the coupled relationship are to be provided by the
anchor cables extending through said ball joint and the stop
fitting.
[0004] FR2465640 discloses a system for transferring persons and
small cargo between a ship and an off shore structure, comprising a
telescoping gangway carried by a platform on the ship. The platform
allows passive rotation around an axis perpendicular to the ship's
deck and limited pivoting of the platform around an axis
substantially parallel to said deck. The gangway is pivotably
connected to the platform by a further axis also extending
substantially parallel to the deck. A hydraulic cylinder is
provided between the platform and the first segment of the gangway
connected to the platform, for compensating for part of the weight
of the platform and for retracting the first segment of the gangway
to a horizontal storage position. A cable extends below the gangway
segments, tensioned by a constant tension winch provided below the
first segment of the gangway, near the platform. A towing cable is
provided between a free end of the gangway and a boom of the off
shore structure. The boom is provided on a special platform of the
structure, which allows the boom to pivot around a vertical axis
over about 270 degrees. A winch is provided for tensioning the
towing cable, either from the gangway or the structure. FR2465640
does not disclose how the towing cable is connected or disconnected
from either the structure of the ship, and does not disclose how
the towing cable is transferred between the ship and the structure,
for coupling or decoupling. The end of the gangway is kept in
closed contact with the structure by maintaining the cables
tensioned by means of the constant tension winches.
[0005] WO98/57845 discloses a system for transferring personnel and
small cargo between a vessel and an off shore structure, wherein
the vessel is provided with a large and complicated transfer
device, comprising a telescoping gangway suspended from an
articulated frame extending well above the gangway. Through the
frame a pilot cable can be led for transferring a ball joint
coupling element to a complementary ball joint coupling element
provided on the off shore structure. In this structure the gangway
is passive and operated by means of the frame. The ball joint
coupling provides for limited rotational movements of the gangway
relative to the off shore structure.
[0006] WO2006/013342 discloses a ship with a gangway for providing
a connection between the ship and an off shore structure such as a
windmill. To this end a runway is provided, fixed on the ship, over
which a first end of the gangway can be guided, between a stored
position on the ship and an extended position. Guide wires can be
provided between the ship and the structure, over which guide wires
the gangway can be guided to the structure. The gangway is thereby
supported by the guide wires and the runway and its free end can be
supported at the off shore structure. The cables are kept taut at
all times during use and the first end will move over the run way
in order to compensate for movement of the ship relative to the
structure.
[0007] One of the objects of the invention is to improve a vessel
including a motion platform.
[0008] Another object of the invention is to reduce manufacturing
and/or operational costs of a motion platform.
[0009] At least one of these and other objects are achieved with a
vessel, assembly, platform and/or method according to the present
description.
[0010] In a first aspect this disclosure can be characterised by a
motion compensation platform, which platform comprises at least one
carrier for bearing, moving and/or transferring a load and a
gangway provided with a first end pivotably connected to the
carrier and an opposite second end. A multiple number of first
actuators is provided for moving the carrier relative to the
vessel, and a control system is arranged for driving the multiple
number of first actuators. A cable extends from the vessel and/or
the motion platform to at least a position at or near the second
end of the gangway. During movement of the gangway to and/or from
the structure the cable can in embodiments be carried by the
gangway, for example at or near the second end thereof.
[0011] In a second aspect this disclosure can be characterised by
an assembly of a vessel according to the invention and a mooring
element, wherein the mooring element comprises a counter coupling
element for coupling to the cable and/or to a coupling element
connected to the cable.
[0012] In a third aspect this disclosure can be characterised by a
motion platform, particularly but not exclusively suitable for a
vessel as described, which platform comprises at least one carrier
for bearing, moving and/or transferring a load, a gangway provided
with a first end pivotably connected to the carrier and a second
end for contacting a target area, a multiple number of first
actuators for moving the carrier relative to the vessel. At least a
second actuator is provided for moving the gangway relative to the
carrier, whereas a control system is arranged for driving the
multiple number of first actuators and for driving the at least one
second actuator. A cable is provided which is or can be carried at
or near the second end of the gangway. The cable will preferably at
least be carried by the gangway during movement of the second end
of the gangway towards or away from a second vessel or structure
with which the cable is to be connected.
[0013] In a fourth aspect this disclosure relates to a method for
providing a gangway between a first vessel and second vessel or a
structure, such as an off-shore structure, wherein the gangway is
carried at a first end by a motion platform on the vessel and has
an opposite second end. Further a cable is provided, connected to
the vessel and/or the platform, for example by a winch. The method
comprises, but is not necessarily limited to the steps of: [0014]
moving the gangway by the platform, preferably in an active mode,
such that the second end is brought to a position near or in
contact with the second vessel or structure; [0015] connecting the
cable to the second vessel or structure; [0016] allowing the motion
platform and/or gangway to follow the movements of the vessel
relative to the movements of the second vessel or structure,
especially by bringing the platform and/or gangway from an active
mode into an inactive mode.
[0017] In embodiments the cable is carried by the gangway to and
from the structure, and is preferably released from the gangway
once it is connected to both the vessel and the structure.
[0018] In clarification of the invention, exemplary embodiments of
a vessel, motion platform, method and use according to the
invention will be further elucidated with reference to the drawing.
In the drawing:
[0019] FIG. 1 shows a schematic perspective view of a vessel
according to the invention;
[0020] FIG. 2 shows a schematic diagram of the vessel shown in FIG.
1;
[0021] FIG. 3 shows a schematic perspective of a motion platform
according to the invention;
[0022] FIG. 4 shows a flow chart of an embodiment of a method
according to the invention;
[0023] FIG. 5A-K schematically a series of steps in providing and
removing a gangway;
[0024] FIG. 6A-D schematically steps of an alternative
embodiment;
[0025] FIG. 7 in top view schematically an embodiment of an
assembly of the present invention; and
[0026] FIG. 8A-D disclose an embodiment of a coupling element and
counter coupling element for coupling a cable.
[0027] In this description, identical or corresponding parts have
identical or corresponding reference numerals. In the drawing,
embodiments are given only as examples. The parts used there are
mentioned merely an as example and should not be construed to be
limitative in any manner. Other parts too can be utilized within
the framework of the present invention.
[0028] According to embodiments of the invention a gangway is or
can be used for transferring a cable from a vessel to another
vessel or structure, for providing a connection between the two.
Then the cable and, optionally, the gangway and/or platform are
used to keep the second end of the gangway, opposite the first end
which is connected to the platform, in close proximity off and
preferably in contact with the second vessel or structure.
[0029] In this description reference is made to for example second
vessels, structures such as off shore structures and the like, with
which a connection is to be made by a gangway of a vessel according
to this disclosure. In this description second vessel and structure
are interchangeable, unless otherwise specified, and may both be
referred to as structure 2.
[0030] In this description a gangway is to be understood as an
element or assembly for transferring or allowing to transfer
people, cargo, animals or other loads between a vessel and another
vessel or structure, the gangway bridging at least part and
preferably all of a gap or distance between the vessel and the
second vessel or structure or at least a landing area thereof.
[0031] In this disclosure a cable has to be understood as any
element which is known to be used or suitable for connecting a
vessel to another vessel or structure, such as but not limited to
metal, plastic or fibre cables, such as mooring cables or lines,
chains, rods and the like. In this description second vessel or
structure has to be understood as including but not limited to sea
going vessels and ships, hulls, off-shore structures such as
drilling platforms, windmills and the like, for example
permanently, semi-permanently or temporarily placed in and/or on
open water.
[0032] In this description a Stewart platform is described as the
basis for a motion platform, by way of example only. Other types of
motion platforms can be used within the context of the invention
too.
[0033] FIG. 1 schematically shows an embodiment of a vessel 1
according to the invention. With this vessel 1, a load such as for
instance people, animals, goods and/or other loads can be
transferred from the vessel 1 to a target area, such as for example
another, second vessel or a structure, such as for example an
off-shore structure 2, and vice versa. The structure 2 can for
example be a frame or base of, for instance, a windmill or platform
at sea 3. For transfer, the vessel 1 is provided with a motion
platform 4. This platform can be designed to compensate for motions
of the vessel 1 relative to the structure 2, for the purpose of
holding a part of the platform or connected elements contacting the
structure 2 relatively still relative to the structure 2, so that
for instance people such as windmill construction personnel can
transfer relatively safely. The motions of the vessel 1 that can be
compensated may comprise linear motions such as surge (vessel moves
from front 1A to back 1B), heave (up and down) and sway (sideways),
and rotating motions such as roll (bow from left to right) yaw (the
vessel 1 rolls from left to right) and pitch (bow up and down).
Naturally, the motions of the vessel 1 are often combinations of
these linear and rotational motions.
[0034] This transferring from or to the vessel 1 should of course
not be understood as limited to the transfer from and/or to
windmills 2. In principle, transferring can be carried out between
the vessel 1 and any other surrounding structure or vessel 2. The
vessel 1 is suited for transferring, for instance, people, animals
and/or loads to, in principle, any offshore construction, such as
platforms at sea 3 and/or other constructions in the water 3, etc.
In certain embodiments, a vessel 1 according to the invention is
designed for transferring to any part connected to the fixed world,
such as a quay, a levee, cliffs, steep rocks, (sea)floor etc. In
certain embodiments, a vessel 1 has been made suitable for
transferring to other moving elements and/or floating elements,
such as, for instance, other vessels. To that end, with the aid of,
for instance, a camera, optical sensor or the like, the motions of
such a moving element can be registered and be compensated by the
active components of the platform.
[0035] In the embodiment shown, the motion compensation platform 4
is provided with a carrier 6 and a multiple number of first
actuators, implemented as six hydraulic cylinders 5a, for moving
the carrier. Such a motion platform 4 is for example known as
simulation platform, as "Stewart" platform. The carrier 6 can be
designed to be movable in six degrees of freedom. However, the
carrier can also be designed to be movable in less degrees of
freedom, e.g. three degrees of freedom, e.g. with respect to roll,
yaw and pitch. The platform 4 further comprises a gangway 16 having
a first end 16a and a second end 16b. The gangway first end 16a is
pivotably connected to the carrier 6. Further, the gangway second
end 16b, opposite the first end 16A is or can be brought into
contact with the structure 2. The gangway 16 can be moved with
respect to the carrier 6 by driving at least a second actuator 5b
provided by the platform. In operation, during at least a certain
period the second end 16b of the gangway 16 can be held
substantially stationary relative to the windmill 2 by actively
driving the multiple number of hydraulic cylinders 5a and the at
least one second actuator. To that end, the platform is further
provided in a known manner with motion sensors and a control system
for appropriately driving the respective actuators.
[0036] FIG. 3 shows a schematic perspective of a motion platform 4
according to the invention. The platform includes a framework or
base 50 rigidly fixed to the vessel 1. The multiple number of first
actuators 5 bear the carrier 6 on the framework 50. The carrier 6
is provided with a top surface 6 on which the gangway 16 is
pivotably mounted via a pivot mechanism 25. Further, FIG. 3 shows
the second actuator 5b enabling the second end 16b of the gangway
16 to be lifted and lowered with respect to the carrier 16. More
specifically, the second actuator 5b is arranged for pivoting the
gangway 16 with respect to a first pivoting axis A substantially
parallel to the carrier 6 and transverse with respect to a
longitudinal axis L of the gangway 16. Thus, by pivoting the
gangway 16 around the first pivoting axis A, the second end 16b of
the gangway can be lifted or lowered to follow a target height of
the target area 2.
[0037] The platform is further provided with another second
actuator (not shown) that is arranged for pivoting the gangway 16
with respect to a second pivoting axis B substantially transverse
with respect to the plane wherein the carrier 6 extends, so that
the gangway may swivel clockwise or counter-clockwise in a
substantially horizontal plane or at least in a plane or parallel
to a plane perpendicular to said axis B and/or substantially
parallel to the plane of the carrier 6.
[0038] The gangway includes a first gangway section 26a and a
second gangway section 26b mutually interconnected via a
translation mechanism 28. The first gangway end 16a is provided on
the first gangway section 26a, while the second gangway end 16b is
provided on the second gangway section 26b. The platform is further
provided with a second actuator, e.g. integrated in the translation
mechanism 28, for moving the second gangway section 26b with
respect to the first gangway section 26a substantially along the
gangway longitudinal axis L, so that the gangway second end 16b may
follow a lateral, horizontal movement of the vessel with respect to
the target area 2. The gangway 16 can thus be extended and
retracted by means of the mechanism 28 and the relevant second
actuator.
[0039] In embodiments by compensating a vessel movement via
actively driving some or all second actuators 5b, a motion
compensation in three degrees of freedom can be performed such that
the carrier 6 has to compensate for the other three degrees only.
In embodiments compensation, as far as necessary, can be performed
in more than three, for example four, five or all of the six
degrees of freedom by actively driving the first actuators.
[0040] It is noted that in another embodiment of the motion
platform according to the invention, another design can be
implemented, e.g. having only two second actuators or only one
second actuator for the gangway extension and retraction. Then, the
carrier has to perform a motion compensation in more degrees of
freedom, e.g. four degrees or five degrees of freedom.
[0041] FIGS. 1 and 2 show a cable 20, at a first end connected to
the vessel 1 by a winch 21. In embodiment such winch can be a
standard winch or can for example be an auto recovery winch, render
and recovery winch or constant tension winch. An opposite second
end of the cable is connected to the structure 22 by a coupling
element 23, connected releasably to a counter coupling element 24
on the structure 2. The counter coupling element 24 can be formed
by or part of a mooring element 25 as will be discussed. With the
cable 20 the distance between the vessel and the structure can be
defined, at least maximised, and/or controlled by defining the
length X of the cable 20. The tension in the cable 20 can be
adjusted and/or controlled, for example by the winch 21, and the
cable 20 can be pulled taut.
[0042] In embodiments the gangway 16, especially the second end 16b
thereof can be held by and/or pushed against the structure 2, for
example against, into and/or onto a mooring element 25. In
embodiments the gangway, especially the second end 16b can be kept
in a relatively constant position relative to the structure 2, for
example in, on and/or over the mooring element 25, as a result of
the tension in the cable being controlled, especially kept taut and
the platform 4 and/or the gangway 16 being controlled such that the
end 16b of the gangway 16 is pushed against the mooring element 25.
In such embodiment the platform 4 and/or gangway 16 can be
controlled such that they only follow the movements of the vessel 1
in stead of compensating for the movements thereof relative to the
structure or second vessel 2. In embodiments in which the gangway
16 has two or more parts 26A, B movable relative to each other in a
length direction L of the gangway 16, such as for example shown in
FIGS. 3, 5, 6 and 7, the second end 16B can be held in position
relative to the structure or second vessel 2, especially relative
to a mooring element 25 thereon, by extending and reducing the
axial length of the gangway 16, by movements of the second part 26b
relative to the first part 26a, and for example allowing the
gangway to pivot freely around the first pivot axis A and/or second
pivot axis B and/or for example by holding the platform in a fixed
position or by allowing the platform to follow movements of the
gangway substantially passively. Substantially passively or not
active can be understood in this context as including but not
limited to allowing the platform, especially the carrier to follow
movements of the first end of the gangway 16 by not actively
controlling the pressure of the first actuators 5a, and/or by
actuating the first actuators 5a only to such extend that the
platform 4 does not pull the second end 16b away from the structure
or second vessel 2. In embodiments the cable 20 can be controlled
such that the majority or even all of the movements of the vessel 1
relative to the structure or second vessel 2 can be compensated for
by adjustments in the length of the gangway 16 between the first
and second ends 16a, 16b and pivoting of the gangway 16 relative to
the platform 4, especially the carrier, for example around the
first and/or second axis A, B. Such pivoting can be free pivoting,
e.g. without actuation by any second actuator, or can at least
partly be controlled by at least one second actuator 5b. In all of
these embodiments the first and/or second actuators 5a, 5b could be
controlled to for example dampen movements of the parts of the
platform and/or gangway relative to each other and/or relative to
the vessel 1.
[0043] In embodiments a vessel, especially a platform 4 with a
gangway 16 can be used in two modes: an active mode for
transferring an end of the cable 20 and/or the second end of the
gangway 16 from the vessel 1 to a structure or second vessel 2 to
which a connection is to be made, and a second mode in which the
platform is operated more passively than in active mode, and at
least partly follows movement of the gangway and does not
compensate for the movements of the vessel or at least compensates
for movements of the vessel to a lesser extend than in active mode.
In active mode at least the first actuators 5a and preferably also
second actuators 5b can in embodiments be controlled actively,
based on the sensor signals of sensors 7, as discussed with respect
to and in the prior art as for example disclosed in WO 2007/120039
and/or WO2012/021062, for actively compensating for movements of
the vessel 1 and bringing and holding the second end 16b in a
preferred position relative to the structure or second vessel 2. In
passive mode the position of the second end 16b of the gangway is
not controlled, or at least not only actively controlled by
movements of the platform and/or actuation of the first and second
actuators 5a, 5b, but at least partly effected by the fact that the
vessel 1 is kept at a relatively fixed distance from the second
vessel or structure 2 by the cable 20, such that the second end 16b
of the gangway 16 can be kept substantially in a preferred position
relative to the second vessel or structure 2 without the necessity
of fully compensating for the movements of the vessel 1 relative to
the second vessel or structure 2. This allows for a far less
complicated system to be used, which can for example have a lighter
platform 4, smaller actuators 5, a smaller hydraulics or pneumatic
or electrical system for driving the actuators and/or, less
complicated sensors. In embodiments a vessel 1, assembly, or
platform according to the description can moreover enhance safety,
since even if the platform 4 is not actively controlled by the
system, for example due to power failure, the second end 16a can be
kept in close proximity of the second vessel or structure, for safe
transfer of for example persons and/or cargo.
[0044] FIG. 2 shows a schematic diagram of the vessel 1. The
control system 8 is connected to the motion sensors 7 for receiving
motion sensor data, for instance the rocking of the vessel 1 in the
water 3. With the aid of these measurement data, during use, at
least in active mode, a first driving signal and a second driving
signal are generated for driving the hydraulic cylinders 5a and the
at least one second actuator 5b, respectively, for moving the
carrier 6 with respect to the vessel 1 and for moving the gangway
16 with respect to the carrier 6, respectively, in order to bring
and at least temporarily maintain the second end 16b of the gangway
substantially stable relative to the target area. In order to
generate the driving signals, the control system 8 is provided with
processor 13. The control system also includes a memory 14.
Processing these measurements and actively driving the hydraulic
cylinders 5a and the at least one second actuator 5b is a task to
be performed by the control system 8.
[0045] The actuators 5a, 5b may include pneumatic and/or hydraulic
means, linear motors, electric driving elements etc. In the
embodiments shown in FIG. 1, the pneumatic means 9 comprise at
least one pneumatic cylinder 10 which is placed approximately in
the centre of the motion compensation platform 4 and is connected
via pipes 15 to a pressure compensator in the form of an
accumulator 11 for buffering compressed air, and a compressor 12
for compressing air. After filling with compressed air in the
pneumatic cylinder 10 and the accumulator 11, after provision of a
load, the cylinder 10 will remain pressurized and it can continue
bearing at least a part of the load. The pneumatic cylinder 10 may
have the property of passively moving along in its longitudinal
direction. Motions of the carrier 6 in the longitudinal direction
of the cylinder 10 are followed by compression and expansion of the
air in the cylinder 10 and the accumulator 11. Small pressure
losses in the pneumatic cylinder 10 through, for instance, friction
can be measured and compensated with the aid of, for instance, the
compressor 12 and/or the control system 8. Such pneumatic means 9
are known per se from the so-called `heave compensation` systems.
By placing this longitudinal direction in the direction of gravity,
a great force, e.g. that of the weight of the carrier 6 and the
load, will be continuously absorbed by the passive pneumatic means
9, and hence also in the case of a defect in the active elements of
the motion compensation platform 4 such as, for instance, the
sensors 7, the control system 8 and/or the hydraulic cylinders. In
particular embodiments, the pneumatic means 9 are advantageously
placed in other directions, for instance for compensating tilting
motions of the carrier 6 after, for instance, a defect. In this
way, upon a defect of an element such as a cylinder 5, the
pneumatic means 9 can prevent the motion compensation platform from
making a relatively unsafe motion, such as, for instance,
collapsing. Defects that might occur are, for instance, power
supply failure or valves in the active hydraulic system becoming
wedged. Naturally, also, other, preferably passive, pressure
systems 9 can be utilized within the framework of the invention. In
certain embodiments, instead of and/or in addition to pneumatic
means 8, that is the cylinder 10, at least one spring can be
utilized as passive element 10, for instance a spiral and/or gas
spring. The pneumatic means 9 can, in principle, comprise different
types of pressure elements such as, for instance, hydraulic means
and/or elastic means and/or a pulling element, etc. Naturally, one
or more pressure elements can be utilized. Depending on, for
instance, the expected use, desired precision and/or economic
considerations, one particular type, one particular amount and/or
positioning can be selected. A passive pressure system 9 provides
security in that it will, in principle, not fail and can remain
functional without continuous actuation. Also, such a passive
system 9 can remain of limited complexity. In embodiments no such
pneumatic means are provided or they are designed differently, for
example hydraulic.
[0046] In particular embodiments, the motion sensors 7 comprise
known motion sensors 7 such as for measuring motions of the vessel
1, for instance accelerometers or dynamometers. With known
accelerometers, the motion of the vessel 1 relative to the fixed
world can be measured. Also, in particular embodiments, other types
of sensors 7 can be utilized, such as for instance cameras, GPS
(Global Positioning System), sensors utilizing electromagnetic
waves, sonic waves, etc. The sensors 7 may measure the position of
the vessel 1 relative to one or more elements in the surrounding
area, such as for instance towards another vessel 1 and/or the
fixed world. The information the control system 8 receives from the
motions sensors 7 is processed via, for instance, pre-programmed
algorithms so that the actuators 5a, 5b can be driven for holding
the second end 16b of the gangway 16 approximately stationary
relative to the target area 2. In passive mode preferably at least
the second actuator 5b for extending and retracting the gangway is
actively controlled, for example advantageously only that second
actuator.
[0047] Advantageously, the motion sensors include orientation
sensors and sensors for measuring a relative distance towards the
target area, so that another orientation and/or another position
can be measured, thereby avoiding the use of absolute position
sensors. As a result, the motion sensors can be implemented in a
relatively cheap manner.
[0048] The measurements may further include providing measurement
data performed from another structure, e.g. another vessel,
concerning movements of the vessel at hand. Measurements may also
include providing laser data or video data to retrieve relative
position data.
[0049] In this respect it is noted that the use of orientation
sensors and sensors for measuring a distance towards the target
area can not only be applied with the method according to the
description, but also, more generally, in combination with a method
for compensating motions of a vessel, comprising the steps of
measuring motions relative to at least one element in a target area
and driving a multiple number of first actuators for moving a
carrier relative to the vessel.
[0050] The measurements may include providing sensor data of
motions of the vessel, the platform and/or the gangway, preferably
the second end of the gangway, relative to the target area 2. In
particular, vertical position data of the second end 16b of the
gangway can be obtained by measuring the height of said gangway
second end 16b relative to the target area 2, thereby enabling the
control system 8 to follow the target area height relatively easily
and accurately by driving the second actuator controlling pivoting
the gangway relative to the first pivoting axis A.
[0051] The operation of an embodiment of the motion platform 4 is
in general approximately as follows. When the vessel 1 is close to
the structure or second vessel 2, the platform 4 is activated in
active mode. Vessel motions are measured via the sensors 7, which
measurement data is used as input for the control system 8. In
response to the measurement data, a first driving signal and a
second driving signal is generated for driving the respective
actuators. Through continuous adjustment of the actuators 5a, 5b
the gangway second end 16b will be able to virtually stand still
relative to the structure 2, at least temporarily. The cable 20 is
transferred to the structure or second vessel 2 preferably by the
gangway 16, and is coupled to the second vessel or structure 2, for
example by the coupling element 23 and counter coupling element 24
and/or mooring element 25. Then the cable 20 is released from the
gangway 16 and pulled taut by the winch 21. The second end 16b of
the gangway is preferably pushed against the second vessel or
structure 2, especially to a mooring element 25. The platform is
brought in passive mode, or fixed in a position. In this position
persons, loads, animals and the like can safely be transferred from
the vessel 1 to the second vessel or structure 2 or vice versa.
[0052] Coupling element 23 and counter coupling element 24 can be
any known suitable set of cooperating coupling elements, such as
for example hook and eye, loop and boulder, magnets, or any such
elements known in the art and suitable for making a reversible
connection. In FIGS. 5 and 6 by way of example only a hook is shown
as coupling element 23, whereas an eye (not shown) is used as
counter coupling element 24.
[0053] In FIG. 8A-D an embodiment is shown of a coupling element 23
connected to a cable 20 and a counter coupling element 24 for
cooperation therewith. In FIG. 8A-D schematically steps of a
sequence for coupling a cable 20 to a structure 2 such as an off
shore structure are shown. As is shown in FIG. 8A schematically a
first coupling element 23 can be provided having basically a hook
shape or anchor shape. It can have a central leg 34 and a first and
a second prongs 35, 36, one on either side of the central leg 34.
The cable 20 can be connected to the free end of the leg 34. In
this embodiment the end 16B of the gangway 16 is provided with a
rod 37 over which a first prong 35 can be hooked, for carrying the
first coupling element 23 towards the structure 2. On the structure
2, preferably at or near a mooring element 25, if applicable, the
second coupling element 24 is provided, comprising a second rod 38.
As is shown in FIG. 8B the second prong 36 can be moved over and
hooked to the second rod 38 by manipulating the element 23 by
movement of the gangway 16. In FIG. 8B the element 23 is shown,
hooked over both rods 37, 38.
[0054] Once the second prong 36 has been hooked over the second rod
38, the gangway end 16B can be retrieved slightly, such that the
first rod 37 is pulled away from the element 23, out from under the
first prong 36, as is shown in FIG. 8C. The cable 20 is now
connected to the structure 2, especially to the element 24. Then
the cable can be tightened by the winch 21, and the end 16B,
especially the platform 31 can be moved into the space 29 of the
element 25 through the opening 29A as described, for properly
coupling the gangway with the structure 2.
[0055] Should the cable 20 be released, the same sequence can be
performed, in reversed order. Preferably the rods 37 and 38 are
positioned such that they do not interfere with a proper
functioning of the coupling between the gangway 16 and the element
25 as described. For example the rods 37, 38 can be placed to a
side of the gangway 16, or spaced slightly apart from the edge 32
of the platform 31, e.g. closer to the first end 16A of the
gangway, such that the rod 37 does not enter into the space 29.
[0056] Obviously other coupling elements 23, 24 can be used, or
differently shaped. For example the element 23 can have more than
two prongs, for example three or four, as used in a grapnel or
grapples or grapple irons, dredging hooks and the like.
[0057] This coupling as shown in FIG. 8 releases the cable
automatically from the gangway 16, preventing undesired and
excessive forces acting on the gangway and/or on the cable 20. More
in general it may be preferable to release the cable 20 from the
gangway once the cable has been properly connected to the structure
2 for that purpose.
[0058] Since the platform 4 and the gangway 16 can be actively
controlled, the end 16 and thus the first coupling element 23 can
be positioned accurately and relatively easily with respect to the
second coupling element 24, without the necessity of using a pilot
line or the like to be transferred separately from the ship 1 to
the structure 2 or vice versa, as is shown in the prior art. The
cable 20 can be coupled directly and accurately. Whereas the cable
can be released from the gangway 16 easily after coupling. The
cable 20 and the gangway can then cooperate in holding the gangway
end 16B in the proper position relative to the structure 2.
[0059] When releasing the gangway 16 from the second vessel or
structure 2 the platform 4 is brought into active mode again,
whereas the cable is released from the second vessel or structure 2
and, if applicable, coupled to the gangway again. Then the gangway
is retracted and/or rotated and/or pivoted back onto the first
vessel 1.
[0060] In FIG. 5A-K schematically a series of steps is shown in
providing a gangway 16 between a vessel 1 and a second vessel or
structure 2. In FIG. 5A the platform 4 is shown in a stable state,
with the gangway 16 pivoted down, such that the second end 16b
thereof rests on the deck 27 of the vessel 1. An operator P can
mount the platform 4 via the gangway 16. On the left hand side of
the FIG. 5A-K schematically part of a structure 2 is shown, which
by way of example comprises a central column 2A and a deck 2B. On
the deck 2B a mooring element 25 is mounted, for example bolted to
the deck 2B. The mooring element 25 has an in top view
substantially triangular catching space 29 having an opening 29a
open towards the side of the vessel 1 or at least an edge of the
deck 2B, into which the second end 16B of the gangway 16 can be
inserted. The space 29 is provided at a top side thereof with two
guide flanges 30 extending inward from two opposite sides of the
space 29. The second end 16B comprises a plate or platform element
31, for example having a substantially semi circular edge 32. The
plate or platform element 32 can be inserted into the space 29 such
that it is at least partly enclosed below the flanges 30, such that
it cannot be removed from the space 29 in any direction other than
through the opening 29A. Thus the second end 16B can be enclosed
within the space 29 in all but one direction.
[0061] In FIG. 5B the operator P has mounted the platform 4 and
will actuate the system such that the end 16B of the gangway 16 is
lifted from the deck 27. FIG. 5C shows the platform 4 with the
gangway 16 having been rotated over an angle of about 180 degrees
from the position in FIG. 5B, such that the second end 16B faces
the structure 2. In this position the platform 4 can still be in a
fixed position, i.e. not in an active position compensating for
movements of the vessel. In for example this position the system
can be brought in active mode, such that the platform 4 will start
compensating for the movements of the vessel relative to the
structure 2, especially relative to the mooring element 25. As
shown in FIG. 5D the operator P can actuate a second actuator 5b
such that the second part 26B of the gangway 16 is moved forward,
i.e. such that the gangway 16 in the direction L is extended,
bringing the second end 16B closer to and in contact with the
mooring element 25. The cable 20 is allowed to follow the relative
movement of the second end 16b, such that the coupling element 23
is brought to the mooring element 25 by the gangway 16. As shown in
FIG. 5E the second end 16B, especially the plate or platform
element 32 is pushed into the space 29. The coupling element 23 can
be coupled to the counter coupling element 24, and the cable can be
pulled taut by the winch 21.
[0062] When or after the cable 20 has been properly coupled to the
structure or second vessel 2, the platform can be brought out of
the active mode, for example into the inactive mode. Preferably the
gangway 16, especially the second end 16B thereof is actively
pushed into the space 29, preferably by actuating the relevant
second actuator 5b used for extending and retracting the gangway 16
in length direction. This can be done by moving the second part 26B
relative to the first part 26A in the length direction L.
Alternatively the platform can be used for providing sufficient
pressure to the gangway, for example by partly actuating at least
one of the first actuators. As is shown in FIG. 5F then a staircase
33 can be mounted to the platform 4, for easy access to and from
the carrier 6, off the deck 27. Since the platform can be kept
stationary relative to the deck 27 this is very easily done. As is
shown in FIG. 5G a person P2 can easily move over the gangway 16 to
the structure 2 or return from the structure 2 to the vessel 1.
During such transfer preferably the gangway 16, especially the
second end 16B is pushed against the mooring element 25, into the
space 29, whereas the cable 20 is kept taut. In embodiments the
gangway 16 is allowed to freely pivot around the first axis A
relative to the platform 4, or at least the carrier. In embodiments
the carrier 6 or at least the gangway 16 can pivot freely around
the second axis B as well.
[0063] Preferably the space 29 in side view also has a
substantially triangular shape or at least widens towards the
opening 29A, such that the platform element or plate 32 can pivot
within the space 29 over an angle .alpha. around an imaginary axis
C parallel to the deck 2B and to the opening 29A, whereas
preferably the space 29 and the platform element or plate 32 are
designed such that the platform element or plate 32 can pivot
within the space over an angle 13 around an imaginary axis D (FIG.
7) perpendicular to the deck 2B and the axis C, in order to allow
the gangway to pivot relative to the structure 2 too. Alternatively
or additionally the mooring element 25 could be mounted to the
structure 2 such that it can pivot relative to the structure 2.
Thus the gangway 16 can follow relative movements of the vessel,
with the platform in a fixed position or at least in a mode in
which it not fully compensates for the relative movements of the
vessel 1.
[0064] FIG. 5 H-K show schematically steps of retracting the
gangway 16. In FIG. 5H the staircase is removed, the platform 4 is
brought back into active mode and the cable 20 is slackened and
released from the structure by releasing the coupling element 23
from the counter coupling element 24. The cable is again supported
by the gangway 16, for example by coupling the coupling element 23
to the gangway or in any other suitable way. Then the second end
16B is retracted from the space 29 in the mooring element 25, as is
shown in FIG. 5I, for example by retracting the gangway 16 and/or
by movement of the platform 4. Then the platform may be brought out
of the active mode again and can for example be settled into a
neutral position, as is shown in FIG. 5J. From this position the
gangway 16 can be rotated over 180 degrees again, for example by
rotating the carrier 6, back above the deck 27 whereafter the
gangway can be brought into the position as shown in FIG. 5K,
allowing the operator P to leave the platform over the gangway
16.
[0065] During retracting the gangway 16 the cable may be rewound
onto the winch or otherwise retrieved too.
[0066] In FIG. 6A-D steps of an alternative method are shown,
wherein the mooring element 25 is carried to the structure 2 by
means of the gangway 16. In this embodiment with the platform 4 as
shown in FIG. 6A the mooring element is mounted onto the second end
16B of the gangway 16, for example by sliding it with the space 29
over the plate or platform element 32 or just the end 16B. On the
structure 2 people P3 may be available for assistance. As described
before, with the platform not in active mode, the gangway 16 is
brought in a position above the deck and is then rotated outward,
to the position shown in FIG. 6B, in which the platform may be
switched into active mode. The cable 20 may already be connected to
the mooring element, for example using coupling and counter
coupling elements 23, 24, or otherwise. In embodiments the cable 20
could even be fixedly connected to the mooring element 25. From the
position in FIG. 6B the second end 16B with the mooring element is
brought to the structure 2, especially to a deck 2B or such surface
for mounting the mooring element 25. The cable is released to allow
for such movement of the mooring element end/or second end 16B.
[0067] FIG. 6D shows the position in which the mooring element 25
has been placed on the structure 2, with the platform still in
active mode. The persons P3 on the deck 2B of the structure 2 can
mount the mooring element 25 properly to the structure, permanently
or temporarily, for example by bolting, screwing, welding, magnets,
form fitting elements, or any other suitable elements or means.
During the mounting of the mooring element 25 the platform 4 is
preferably kept in active mode, such that no undesired forces are
exerted on the mooring element by the gangway during mounting. Once
the mooring element 25 has been properly placed and, where
necessary, the cable 20 has been attached to the structure 2 and/or
mooring element 25 and has been tensioned, such as pulled taut, the
platform 4 could be brought out of the active mode.
[0068] When retracting the gangway 16 again, for example after it
has completed it's function with respect to the structure 2, the
mooring element 25 could be left in position on the structure 2,
for example for future use in combination with the vessel or a
similar vessel. Alternatively the mooring element 25 could be
released from the structure 2 and retracted with the gangway 16 for
further use with the same or other structures 2. A mooring element
25 can be provided with appropriate connecting elements, such as
pins, screws, bolts, rivets, holes or openings, magnets or any such
means for connecting the mooring element 25 to the structure.
[0069] In FIG. 7 in top view schematically a mooring element 25 is
shown mounted on the second end 16B of the gangway 16, for carrying
the mooring element 25 to or from the vessel form or to the
structure 2. As can be seen the mooring element 25, especially the
space 29 can be open towards a top side of the element 25, between
the flanges 30. However, such element 25 could also be closed to
the top side 34, and could be differently shaped and/or
dimensioned. In other embodiments the mooring element 25 could be
designed to fit within the second end 16B of the gangway, for
example by providing an opening in the plate or platform element 32
which can be placed over the mooring element, for example forming
more or less a ball joint type connection.
[0070] The method for compensating motions of a vessel can at least
partly be performed using dedicated hardware structures, such as
FPGA and/or ASIC components. Otherwise, the method can also at
least partially be performed using a computer program product
comprising instructions for causing a processor of the computer
system to perform the above described steps of the method according
to the invention. Processing steps can in principle be performed on
a single processor, in particular steps of providing first and
second driving signals for driving the multiple number of first
actuators and the at least one second actuator. However, it is
noted that at least one step can be performed on a separate
processor, e.g. a step of receiving motion sensor data of motions
relative to at least one element in a target area.
[0071] In a system and method of the present invention the gangway
can in embodiments be actively operated, i.e. be in an active mode,
meaning that the relevant second actuator or actuators can actively
move the second end of the gangway relative to the platform cq
carrier thereof, for example by extending or retracting the gangway
and/or changing the angle between the gangway and the platform cq
carrier thereof. In embodiments the gangway can be brought into a
passive mode, in which the or each second actuator for operating
the gangway is or can be passive, meaning that the length and/or
position of the gangway is defined passively by the relative
position of the vessel and the second structure or vessel, wherein
the length variations and/or angle variations are provided for at
least mainly by pulling and/or pushing forces exerted on the
gangway by the vessel and/or structure or second vessel. In
embodiments a main aspect can be defined at least by using a
gangway for transferring a connecting cable from a vessel to a
structure or second vessel.
[0072] The invention is by no means limited to the embodiments
specifically shown in the drawings and/or discussed in the
description. Many variations thereof are possible within the
present invention, including but not limited to all combinations of
individual or groups of features as disclosed. The gangway can be
connected differently to the platform, for example by means of a
different hinging structure, such as a connection which allows
pivoting around different axis. The gangway can have more than two
moveable parts, or only one, and can be connected to the platform 4
such that it can move in the longitudinal direction of the gangway
relative to the platform, especially the carrier thereof, for at
least partly compensating for movements of the vessel relative to
the structure. The mooring element can be omitted on the structure,
or can be an integral part thereof. The mooring element can be
designed differently, as long as it allows for a connection with
the platform such that the gangway can apply a force to the mooring
element, preferably at least a pushing force against the mooring
element. The platform can be designed differently, for example with
a different number of actuators and/or different types of
actuators. The second actuator for extending and retracting the
gangway can be designed in any appropriate way, such as for example
but not limited to a hydraulic, pneumatic or electric
piston-cylinder system, a spindle motor, a cable with winch or any
such suitable means known in the art, or combinations thereof, for
example enhanced safety. In stead of or additional to the cable a
more rigid connector could be used between the vessel and the
structure, such as for example but not limited to a pole. In the
embodiments shown the winch is provided on the deck of the vessel.
In other embodiments the winch could be connected to the platform,
for example to a base thereof. The cable can also be connected to
the vessel and/or to the platform in a different manner, for
example to a clamp, boulder or other such means known in the art.
In alternative embodiments additionally or alternatively the winch
or a winch can be placed on the structure, to be used for forming a
cable connection between the vessel and the structure. Such winch
can for example be a winch already available. Alternatively and/or
additionally a crane or other hoisting device could be used for
transferring the cable and/or the mooring element from the vessel
to the structure and/or vice versa and/or for forming the cable
connection. In the embodiments shown and discussed the platform is
operated at least partly by a human operator on the platform. It
shall be clear that it will also be possible to operate such
platform remotely, for example from a cabin or from the deck of the
vessel or from the structure or even from further away, such as
from a shore.
[0073] In embodiments the motion platform can be moved actively
while moving the second end of the gangway to the second vessel or
structure, whereas the motion platform is allowed to passively
follow the relative movements of the vessel after coupling the
cable and/or the second end of the gangway to the second vessel or
structure and/or the motion platform can be moved actively while
moving the second end of the gangway to the second vessel or
structure, whereas the gangway is allowed to passively follow the
relative movements of the vessel after coupling the cable and/or
the second end of the gangway to the second vessel or structure.
The motion compensation platform can comprise or be formed by a
Stewart platform with hydraulic, pneumatic and/or electric
cylinders, as is known in the art.
[0074] In embodiments disclosed herein the platform can be brought
from an active mode to an inactive mode and vice versa. In
embodiments the inactive mode could be designed such that in such
mode the platform is in a fixed position, for example a rest
position wherein the first actuators are kept in a fixed length. In
embodiments an inactive mode can be designed such that the
platform, especially the carrier can still move by length
adjustments of one, some or all of the first actuators, but either
not actively controlled by the system or controlled to an extend
that the platform does not compensate for movements of the vessel,
for example for dampening movements resulting from shock or load
differences.
[0075] These and many other variations and combinations should be
considered also having been disclosed herein.
* * * * *