WO2011138549A1

WO2011138549A1 - Method and system for controlling a connection between two floating structures

Info

Publication number: WO2011138549A1
Application number: PCT/FR2011/050995
Authority: WO
Inventors: Gérard LE CLOEREC; Thierry Pontlevy; Claude Beauger
Original assignee: Technip France
Priority date: 2010-05-03
Filing date: 2011-05-02
Publication date: 2011-11-10
Also published as: AU2011249600A1; EP2566752A1; BR112012028134A2; FR2959478A1; FR2959478B1

Abstract

Method and system for controlling a connection between two floating structures. This system (1100) for the real-time control of at least one connection (1021 to 1024) between first and second structures (10, 12), at least the second structure being a floating structure, the link being connectable by a first end to the first structure and by its second end to the second structure, is characterized in that it comprises: an acquisition means (104, 105, 106, 1152) for acquiring dynamic variables pertaining to the movement of the second end of the link with respect to its first end, a means of determining a parameter representative of the mechanical stresses experienced by the or each link, on the basis of the dynamic variables delivered by the acquisition means, and a means of generating a setpoint value as a function of the parameter or parameters delivered by the determining means.

Description

System and method for controlling a link between two floating structures

The present invention relates to systems and methods for controlling a link between two structures, at least one of which is a floating structure.

For transferring a fluid, such as, for example, liquefied natural gas, between a production unit located at sea, such as a floating gasification unit (FSRU), and a storage unit located near the coast, such as a storage platform, it is known to load or unload intermediate tankers.

To do this, the tanker approaches the unit, whether production or storage. It is positioned, for example, in an edge-to-edge configuration or in a "tandem" configuration, in which the bow of the ship is placed in the axis of the stern of the unit.

Then, a fluid transfer pipe, preferably flexible is unrolled from the unit, to be connected by its free end to the ship.

Once connected, the pipe is suspended freely between its fixed end, on the unit, and its free end, connected to the ship.

The loading and / or unloading can then begin. This is a long operation that can take between a few hours and a few days.

During the phase in which the connection is made to the ship and during the phase in which the line is connected to the ship, whether the fluid is being transferred from one structure to the other the position and the relative speed of the ship with respect to the unit evolve because of, for example, the state of the sea, the state of filling of the ship, etc.

Consequently, the fluid transfer line to connect or connect the two structures undergoes mechanical forces that it is necessary to maintain them within certain limits, if only for security reasons. Thus, the existence of a link between the two structures imposes constraints in the relative positioning of the ship with respect to the unit.

Until now, for example in the tandem configuration, a measuring device located on the unit determines the angle between the axes of the two structures and the distance separating the two structures, by means of a laser reflected by placed reflectors. on the ship. The angle and distance measurements obtained are displayed on a screen in the cabin. An operator compares these measurements with a range of allowed values. Simultaneously, thanks to an interface of a dynamic positioning system of the unit and / or the ship, the operator controls the actuation of the propulsion means of one and / or the other of the structures to modify the relative position of the two structures and, thus, place angle and distance measurements within the range of allowed values.

The intervention of an operator to perform this regulation is not satisfactory. It is difficult for an operator to anticipate the dynamics of the relative movements of the two structures and, consequently, to anticipate the occurrence of a relative positioning that is incompatible with the mechanical properties of the pipe. There are, therefore, risks to the safety of the transfer of the fluid between the two structures: rupture of the pipe, loss of fluid, danger for the operators present on the structures, etc.

To reduce these risks to the maximum, as soon as the relative position of the ship and the unit deviates from a neutral relative positioning, the operator is tempted to shut off the pumps and close the manifold valves of the unit and of the ship, which ensure the circulation of the fluid in the pipe. It is also tempted to urgently disconnect the vessel manifold. These transshipment interruptions of the fluid, which are not always justified, have a direct impact on the time required for the loading and / or unloading of the vessel and ultimately on the operating costs of the installation.

There is therefore a need for automatic monitoring, in real time, of the conditions for using a link between a ship and a storage or production unit.

The invention therefore aims to meet this need.

The invention relates to a real-time control system of at least one link between first and second structures, at least the second structure being a floating structure, the or each link being adapted to be connected by a first end to the first structure and its second end to the second structure. This system comprises: means for acquiring kinematic variables of the movement of the second end of the or each link with respect to its first end; means for determining a magnitude representative of the mechanical stresses experienced by the or each link, based on kinematic variables delivered by the acquisition means; means for generating an instruction as a function of the quantity or quantities delivered by the determination means.

According to particular embodiments, the system comprises one or more of the following characteristics, taken separately or in any technically possible combination:

the link is a fluid transfer conduit for transferring a fluid between the first and second structures.

the acquisition means comprises, for the or each link, an inertial / GPS device for measuring kinematic variables of the second end of said link, each inertial / GPS device comprising an inertial unit and a GPS receiver. the acquisition means comprises at least a first inertial / GPS device for measuring kinematic variables of the first end of the or each link, said at least one first inertial device / GPS comprising a first inertial unit and at least a first GPS receiver .

the one or more GPS receiver (s) functions as a fixed receiver of a satellite positioning system implementing the principle of real-time kinematics, the other GPS receivers functioning as a mobile receiver said satellite positioning system implementing the principle of real-time kinematics.

- The acquisition means further comprises an inertial device / GPS onboard measurement of kinematic variables of the second structure, the inertial device / on-board GPS comprising an inertial unit and at least one GPS receiver.

the means for determining magnitudes representative of the mechanical stresses in the or each link is adapted to take into account the kinematic variables acquired at the present time and / or at a given moment.

the means for determining magnitudes representative of the mechanical stresses in the or each link is able to determine the value of a state function of said link.

the means for generating a setpoint is able to issue a safety instruction to an operating system of an emergency disconnection device of the or each link.

the link being a fluid transfer line, the means for generating a setpoint is able to issue a safety instruction to an actuating system of the pumps and valves allowing the flow of fluid in the or each pipe. the system is capable of transmitting a positioning instruction to a dynamic positioning system of the first structure and / or the second structure.

The invention also relates to a method of real-time control of at least one link between first and second structures, at least the second structure being a floating structure, the or each link being adapted to be connected by a first end. to the first structure and its second end to the second structure, characterized in that it comprises the steps of:

acquire kinematic variables of the movement of the second end of the or each link with respect to its first end,

determining a magnitude representative of the mechanical stresses experienced by the or each link, from acquired kinematic variables,

generate a setpoint according to the one or more quantities determined. The invention and its advantages will be better understood on reading the description which follows, given solely by way of example and with reference to the appended drawings, in which:

- Figure 1 is a schematic representation of a ship edge with a storage unit resting on the seabed;

FIG. 2 is an enlarged representation of FIG. 1 showing the free end of the fluid transfer pipe during its connection to the ship;

- Figures 3, 4, 5 and 6 show, in the plane Y-Z of Figures 1 and 2, the extreme positions of the free end of the transfer line;

FIG. 7 represents, schematically, a first embodiment of the control system according to the invention;

FIG. 8 represents a second embodiment of the system according to the invention; and,

FIG. 9 represents a triplet of security envelopes for the embodiment of FIG. 8.

Referring to Figure 1, a first embodiment of the invention will be presented for the case of the transfer of a fluid between a first fixed structure and a second floating structure.

In Figure 1, the first structure is a storage unit 10 resting on the seabed. The second structure is a tanker 12.

The ship 12 is positioned side by side with the unit 10.

The arrangement 14 for the transfer of fluid connects a first manifold 16 of the unit

10 to a second manifold 18 of the ship 12.

The arrangement 14 comprises a flexible pipe 20 and a connection module 22 which is located between the pipe 20 and the second manifold 18.

As shown in more detail in FIG. 2, the connection module

22 comprises, successively, a connector 30 for fixing the module 22 to a flange of the manifold 18, an intermediate bellows and cardan device 34 in an attempt to mechanically isolate the flange of the manifold 18 of the pipe 20, a device 36 for disconnecting d urgency for disconnecting the pipe 20 of the module 22, and a connector 38 for fixing the module 22 to a fitting end 42 fitted to the free end of the pipe 20.

A support device 35 of the module 22 makes it possible to support the module 22 on the deck of the ship while allowing a relative movement of the module 22 with respect to the ship 12. In addition, the module 22 is equipped with a device for guiding the free end of the pipe. This device comprises a trumpet 39, whose axis extends substantially parallel to the axis of the attachment connector 38, and a winch 40 whose cable passes through the trumpet and is fixed to a pinch 41 equipping the tip 42 of driving 20.

The pipe 20 comprises a first nozzle (not shown) at its fixed end, allowing a connection without degree of freedom, to a connector of the first manifold of the unit 10.

As indicated above, the opposite end, free end of the pipe 20, is provided with a tip 42.

The end piece 42 comprises a guiding device conjugated to that fitted to the connection module 22. The conjugated guiding device comprises a pinch 41 whose axis extends substantially parallel to the axis of the end piece 42. The cable of the guiding device of the connection module pulls the end of the pinch to guide the engagement thereof in the trumpet and properly present the tip 42 of the connector 38 to make the connection.

The pipe is used in a chain.

In the present embodiment, the first end of the pipe 20 is fixed relative to the unit 10. The second end of the pipe 20, equipped with the nozzle 42, is movable relative to the unit 10. The tip 42 is movable during the phase of connection of the pipe 20 to the manifold 18, because it is moved both by the actuation of a suspension winch 48 maintained at a gantry 49 secured to the structure 10, and both by the guiding winch 40 of the guiding device. The tip 42 is movable during the connected phase, whether there is fluid transfer or not, because of the movements of the vessel 12 to which the nozzle 42 is then connected.

Note that the connection module 22 allows relative movements between the tip 42 and the connector 30 of the manifold 18, but with a reduced movement.

It is necessary that the mechanical forces along the pipe during its use remain in admissible ranges to avoid any safety problem. To guarantee this, the positions authorized for driving are previously determined. In the embodiment shown, the position of the pipe is determined by the position of its free end relative to its fixed end.

FIGS. 3 to 6 show the different extreme positions allowed for the end piece 42.

In Figure 3, the tip 42 is in its highest position and closest to the unit 10. In this configuration, the pipe 20 has a minimum allowed radius of curvature. In Figure 4, the tip 42 is in its lowest position and furthest from the unit 10. In this position, the pipe 20 reaches its maximum permitted extension.

In this plane YZ, a rectangular permissible zone is then defined from the extreme positions shown in FIGS. 3 and 4. Thus, in FIG. 5, the pipe 20 is shown while the endpiece 42 is located in the lower right corner of FIG. the authorized zone corresponding to the position of the tip 42 which is the lowest and the closest to the unit 10. In FIG. 6, the pipe 20 is shown while the tip 42 is in the upper left corner of the the authorized zone, corresponds to the position of the tip 42 the highest and furthest from the unit 10.

The ship 12 can also move relative to the unit 10 according to the third dimension (X direction orthogonal to the plane of Figures 1 and 2), an authorized zone of the nozzle 42 in the plane X-Z is also defined.

Finally, these different authorized areas allow to define a security envelope within which the tip 42 must be located so that the efforts of the ngo of the pipe remain below a set of threshold values.

More generally, a security envelope is a complex function depending on several parameters such as the configuration between the first and the second structure, the state of the sea, the state of filling of the one and / or the other structures, the height between the lowest point of the pipe and the level of the waves, the length of the pipe, the structure of the duct sheath, the greater or lesser rigidity of the material of which the pipe is made , the degrees of freedom introduced and the clearances allowed by the connection module for connecting one end of the pipe and a structure, etc.

A security envelope also depends on the phase of use of the pipe. The position of a pipe is preferably controlled with respect to a triplet of envelopes. A first envelope ENV1 is defined, delimiting a reduced volume, within which the forces on the tip and the flexible pipe are very satisfactory. As long as one remains inside this envelope ENV1, there is satisfactory operation of the connection between the tip and the connection module, which is compatible with the transfer of fluid between the two structures.

A second envelope ENV2, surrounding the first, is defined which delimits a volume within which the mechanical forces of the connection and the flexible pipe are such that the pumps must be stopped and the fluid circulation valves in the conduct. The sequence of cutoff of the fluid circulation is initiated as soon as one crosses the boundary between the envelopes ENV1 and ENV2. A third envelope ENV3, surrounding the second, is defined which delimits a volume within which the mechanical forces are such that it is necessary to disconnect the driving of the connection module. The emergency disconnect sequence is initiated as soon as the boundary between the ENV2 and ENV3 envelopes is crossed.

The control system for monitoring the movement of at least one pipe will now be described.

A first embodiment of the control system is shown schematically in Figure 7. In this first embodiment, the entire system is embedded on board the first structure.

The control system 100 comprises a first inertial device / GPS 104 implanted on the fixed end of the pipe and a second inertial device / GPS 106 implanted on the free end of the pipe.

The first inertial device / GPS 104 comprises a first inertial unit 1 10 and a first GPS receiver 1 12.

Inertial units are known to those skilled in the art. The first inertial unit 1 10 comprises three gyroscopes, three accelerometers, and an electronic card making it possible, from the measurements made by these sensors, to calculate, in real time, the vector acceleration of the point of implantation of the inertial unit. By successive integrations, an inertial unit makes it possible to acquire the speed and the position of its point of implantation. It should be noted that for these successive integrations, the inertial unit needs to be calibrated.

The first GPS receiver 1 12 comprises a first antenna 1 14 and a first electronic card 1 16 allowing, from different radio signals emitted by a satellite constellation and picked up by the first antenna, to determine the instantaneous position of the point of implantation. GPS receiver. By successive branches, the first GPS receiver 1 12 can deliver the speed and acceleration of its point of implantation.

The second inertial / GPS device 106 similarly comprises a second inertial unit 120 and a second GPS receiver 122 having a second antenna 124 and a second GPS map 126.

The system 100 includes a main GPS map 130 connected via bidirectional wired connections to the first and second cards 116 and 126.

The main GPS map 130 is able to couple the first and second GPS receivers 1 16 and 126 between them on the principle of real-time kinematics, "Real Time Kinematic" (RTK), known to those skilled in the art. So the first receiver GPS 1 12 operates as a basic receiver of the RTK equipment, while the second receiver 122 operates as a mobile receiver of the RTK equipment.

The system 100 includes a computer 150, a security computer system 170 and a server computer 200.

The computer 150 comprises an input interface to which are connected the first and second inertial units 1 10 and 120 and the main GPS map 130, and this via bidirectional wire connections.

The computer 150 has an output interface by means of which it is connected to the computer security system 170 and the server computer.

The computer 150 is a computer dedicated to calculating the kinematic variables of the relative movement of the free end of a pipe with respect to its fixed end. It comprises storage means, such as a random access memory RAM and a ROM, and calculation means such as a processor. The computer 150 is able to execute the software program instructions stored in its storage means.

The computer 150 executes in particular an application module 160 able to calculate the kinematic variables of the movement of the pipe from the acquired data applied on the input interface.

The instantaneous position data, instantaneous speed and acceleration are transmitted, at the output, to a module 180 and to the server computer capable of generating a quantity corresponding to the mechanical forces experienced by the pipe.

The module 180 is configurable by the choice of at least one security envelope. It takes as input the kinematic variables generated at the output of the module 160 and calculates a magnitude corresponding to the mechanical forces in the controlled pipe.

The notion of envelope spatially translating the mechanical stresses experienced by the pipe, in the embodiment described, the quantity calculated by the module 180 is a Boolean state function of the pipe. For example, this function takes the value zero when the relative position of the free end of the pipe is inside the casing, and the unit value when the relative position of the free end of the pipe is at the bottom. outside of the envelope.

The security computer system 170 is a computer dedicated to security functions. It is suitable for executing a module 190 for generating a security instruction. The module 190 takes as input the value of the quantity determined at the output of the module 180. The module 190 is able to generate, at the output, a setpoint signal addressed to a suitable actuation means with which the system 100 is interfaced.

The system 170 is interfaced, directly, with the system for actuating the valves and pumps located on the unit 10. The setpoint is then a safety instruction adapted to control one or more of these means.

The system 170 is connected to a radio transmission / reception device 250 enabling the establishment of a radio communication with remote systems. It is thus possible to interface the system 100, indirectly, with the actuation system of the valves and pumps of the manifold of the ship 12, the actuation system of the emergency disconnection device on board the ship, and / or the dynamic positioning system of the ship.

The system 170 executes a transmission module 230 capable of transmitting the kinematic variables at the output of the computer 150 to the dynamic positioning system of the ship, as well as a safety instruction generated for the system for actuating the valves and pumps and or the system for actuating the emergency disconnection device on board the ship.

The system 100 includes a server computer 200 connected to the computer 150 and the computer security system 170.

The server 200 executes a human / machine interface module 210, allowing an operator to interact with the system 100.

The server 200 executes a configuration module 220. This module 220 allows an operator to create and save in a database 225 of the server 200 new security envelopes. The module 220 allows the operator to select at least one envelope from a list of envelopes, then to transmit the chosen envelope to the security computer system 170 to configure the computer 150, more particularly the module 180.

To use the system 100, while the pipe 20 is connected to the manifold 18 of the ship 12, the operator first configures the module 180 through the interface 210 by means of the module 220. A security envelope is chosen to configure the module 180.

Then, the first and second inertial / GPS devices 104, 106 periodically measure the position, velocity and acceleration of the first end and the second end of the line 40. These kinematic variables are transmitted to the module 160 which determines the instantaneous relative position of the tip 42. The module 160 transmits this data to the modules 180 and 190 and to the server 200.

The module 180 determines the value of the state function by comparing the instantaneous relative position with the selected security envelope.

The module 190 receives the instantaneous value of the state function. If this is not zero, it is necessary to generate a safety instruction asking for example the closing of the valves and the stopping of the pumps. A security reference signal is transmitted directly from the security computer system 170 to the actuation systems located on the first structure 10. A security reference signal is transmitted via the system 170 and the radio transmission / reception device 250, to the actuating system located on the second structure 12.

Simultaneously, in an attempt to reposition the vessel relative to the unit and, thus respect the positioning constraints of the two structures imposed by the present of the pipe, the instantaneous relative position of the nozzle is transmitted from the computer 150, via the system 170 and the radio transmission / reception device 250, to the dynamic positioning system of the ship.

Alternatively, the instantaneous relative position of the tip is displayed on the screen of a control computer located on the ship. An operator accordingly actuates the ship's dynamic positioning system to replace the tip within the selected envelope which is also displayed on said control screen.

There is shown in Figure 8 a more complex embodiment of the control system. The system 1100 comprises, a first subsystem 1 101, on board the unit 10, and a second subsystem 1 102, on board the ship 12.

The purpose of the system 1100 of FIG. 8 is to control, simultaneously, four flexible lines 1021 to 1024, unrolled from the unit 10 to the ship 12, the unit and the ship being in a tandem configuration.

The pipes are associated in pairs. Each pair of pipes is carried by a wheel 1048, 1049 which is situated on the rear deck of the unit 10. The rotation of the wheel about an axis substantially parallel to the plane of the deck of the unit makes it possible to unroll or wind up a pipe length. A wheel is pivotally mounted relative to the deck of the unit, about a substantially vertical pivot axis perpendicular to the deck plane of the ship. The plane of the wheel thus pivots with respect to the unit as can be seen in FIG. 9.

The first subsystem 1 101 comprises, for each of the four pipes and as in the first embodiment above, a first inertial device / GPS 104 implanted on the fixed end of a pipe and a second inertial device / GPS 106 implanted on the free end of the pipe. A main GPS map (not shown) couples the GPS receivers of the first and second inertial / GPS devices 104 and 106 equipping the same pipe.

Alternatively, for economic reasons, the first two inertial / GPS devices associated with the fixed end of the pipes of the same pair of pipes share their inertial unit. Indeed, the acceleration of the fixed end of these two lines is identical.

The first subsystem further comprises two computers 1 150 and 1 151 of the type of computer 150 presented above. Each calculator is dedicated to the acquisition of the kinematic values of the two pipes of the same pair of pipes. It is connected to the Inertiel / GPS devices associated with these pipes.

The first subsystem 1 101 comprises a first computer security system 1 170 similar to the system 170 presented above, to which are connected the two computers 1 150 and 1 151. The first security computer system 1 170 is interfaced, directly, to the actuation system of the manifold valves and pumps of the unit 10, as well as to the dynamic positioning system of the unit 10.

The first security computer system 1 170 is connected to a first transmission / reception device 1250. A server 1200 is also connected to the system 1 170 and the computers 1 150 and 1 151.

The second subsystem 1 102 comprises an inertial device / GPS 1 105 comprising four GPS receivers 1 1 1 1 to 1 1 14 and an inertial unit 1 1 10.

Two GPS receivers are placed on one side of the ship, while the other two are on the opposite side. The GPS receivers are coupled in pairs using a main GPS map (not shown). Each pair includes a GPS receiver on one edge and a GPS receiver on the opposite side, the GPS receivers not having the same position along the longitudinal axis of the ship.

The inertial unit 1 1 10 is placed substantially on the longitudinal axis of the ship.

The second subsystem 1 102 comprises an onboard computer 1 152, similar to the computer 150 presented above.

The computer 1 152 is able to calculate the position, the speed and the acceleration of any point of the ship from the measurements made by the inertial device / GPS 1 105. In particular, the computer 1 152 makes it possible to acquire the kinematic variables the movement of the four connectors of the manifold 18 of the ship 12 to which the four lines 1021 to 1024 must be connected. The second subsystem 1 102 comprises a second security computer system 1 171 similar to the system 170 presented above, to which the computer 1 152 is connected. The second computer security system 1 171 is interfaced to the actuating system of the valves and pumps of the manifold 18 of the ship 12, the operating system of the emergency disconnect device of the manifold 18, and the dynamic positioning system of the ship 12.

The second security computer system 1 171 is connected to a second transmitting / receiving device 1251. A second server 1201 is connected to the second security computer system 1 171 and the onboard computer 1 152.

In the operation to be described, the first subsystem 1 101 acts as the master and the second subsystem 1 102 as a slave.

In an initial approach step, the ship 12 is positioned relative to the unit 10 in a tandem configuration.

Then, using the interface proposed by the server 1200, an operator, located on the unit 10, establishes a communication link between the first and second subsystems, via the radio transmission / reception devices 1250 and 1251. .

Once this communication is established, the first server 1200 queries the second server 1201 to repatriate data necessary for choosing two triplets of security envelopes. These data are, for example, the nature of the ship, its propulsion capabilities, etc. On the basis of these repatriated data, as well as data present in the database of the first server 1200 (nature of the hoses, propulsion capability of the unit 10, etc.) and other circumstantial data (state of the sea , etc.) two envelopes triplets are chosen by the operator and transmitted to the first computer system 1 170 to configure its module for determining a magnitude representative of the forces imposed on the pipes.

The two chosen envelope triplets are superimposed in FIG. 9. The first envelope triplet ENV1 1, ENV21, ENV31 is associated with the pipes carried by the wheel 1049, while the second envelope triplet ENV12, ENV22, ENV32 is associated with the pipes carried by the wheel 1048.

In a step of making the connection, the first subsystem 1 170 controls the positions of the four connectors of the manifold of the ship relative to the fixed ends of the pipes to be connected. The system 1100 then functions as a guidance system for establishing the connection. The position data, speed and acceleration of the connectors are transmitted via the radio communication link between the second and the first subsystem. At any time, the first subsystem 1 170 determines whether the relative position of a pair of connectors of the manifold of the ship is in the envelope ENV1 1 and whether the relative position of the other pair of connectors of the manifold of the ship is in the ENV12 envelope.

The positioning of the ship with respect to the unit is then regulated so that the connectors are located inside the two envelopes ENV1 1 and ENV12. Once this condition is verified, the connection of each of the pipes to one of the connectors of the manifold can be achieved, without the mechanical forces to be applied to the pipes out of acceptable limits.

In a connected step, the first subsystem controls, for each pipe, the position of its free end relative to its fixed end. The first subsystem controls the relative position of the two free ends of the pipes of a pair of pipes with respect to the second and third envelopes ENV21 and ENV31. Simultaneously, it controls the relative position of the two free ends of the pipes of the other pair of pipes with respect to the second and third envelopes ENV22 and ENV32.

As soon as one of the free ends leaves the first envelope to enter the second, a safety instruction for closing the valves and stopping the pumps is sent, on the one hand, to the actuating system pumps and valves the manifold of the unit and on the other hand to the operating system of the pumps and valves of the manifold of the ship.

As soon as one of the free ends leaves the second envelope to enter the third envelope, an emergency disconnect security instruction is issued to the actuation system of the ship's emergency disconnection device.

Simultaneously, a positioning instruction is sent in the direction, on the one hand, of the dynamic positioning system of the unit and, on the other hand, to the dynamic positioning system of the ship, in order to correct the relative positioning of the ship and unit to replace the free ends of the lines inside the security envelopes.

Note that in the case of a triplet of envelopes, the state function takes, for example, the value 1 when the relative position of the tip is inside the first envelope ENV1, the value 2 when the relative position of the tip is outside the first envelope ENV1, but inside the second envelope ENV2, the value 3 when the relative position of the tip is outside the second envelope ENV2 but inside the third envelope ENV3, the value 4 when the relative position of the tip is outside the third envelope ENV3. The principle of the present invention can be implemented for any type of link between two structures, one of which is floating. Although the present description details the case of a flexible pipe, the link could for example be a rigid pipe, a mooring line, a rigid arm between the two structures, or the equivalent.

For the sake of simplification of the description, the security envelopes presented are envelopes for controlling the instantaneous relative position of the free end of a pipe or a connector. Alternatively, security envelopes taking into account the instantaneous relative speed and / or acceleration of the free end are used by the control system.

In yet another variant, instead of considering only the instantaneous values of different kinematic variables, the control system takes into account the different values of these kinematic variables over a period of time in order to take into account the dynamics of the link and perform trend calculations.

Claims

1. - System (100; 1,100) for real-time monitoring of at least one link (20; 1021 to 1024) between first and second structures (10, 12), at least the second structure being a floating structure, the each link being adapted to be connected by a first end to the first structure and by its second end to the second structure, characterized in that it comprises:

acquisition means (104, 106, 130, 150, 104, 105, 106, 1152) of kinematic variables of movement of the second end of or each link with respect to its first end,

means for determining (180) a magnitude representative of the mechanical stresses experienced by the or each link, based on kinematic variables delivered by the acquisition means,

means for generating (190) an instruction as a function of the quantity or quantities delivered by the determination means.

2. - System according to claim 1, characterized in that said link is a pipe (20) of fluid transfer for the transshipment of a fluid between the first and second structures.

3.- System according to claim 1 or claim 2, characterized in that the acquisition means comprises, for the or each link, an inertial / GPS device for measuring kinematic variables of the second end of said link, each inertial device / GPS (106) having an inertial unit (120) and a GPS receiver (122).

4. System according to any one of claims 1 to 3, characterized in that the acquisition means comprises at least a first inertial device / GPS (104) for measuring kinematic variables of the first end of or each link , said at least one first inertial device / GPS comprising a first inertial unit (1 10) and at least a first GPS receiver (1 12).

5.- System according to claim 4, characterized in that the or one of the first GPS receiver (s) (1 12) functions as a fixed receiver of a satellite positioning system implementing the real-time kinematics principle, the other GPS receivers (122) functioning as a mobile receiver of said satellite positioning system implementing the principle of real-time kinematics.

6. - System according to any one of claims 1 to 5, characterized in that the acquisition means further comprises an onertial device / GPS onboard (1 105) for measuring kinematic variables of the second structure (12). ), said onboard GPS / inertial device comprising an inertial unit (1 1 10) and at least one GPS receiver (1 1 1 1 to 1 1 14).

7. - System according to any one of claims 1 to 6, characterized in that the means (180) for determining magnitudes representative of the mechanical stresses in the or each link is adapted to take into account the kinematic variables acquired at the moment. present and / or at a past moment.

8. - System according to any one of claims 1 to 7, characterized in that the means (180) for determining quantities representative of the mechanical stresses in the or each link is able to determine the value of a state function. said link.

9. - System according to any one of claims 1 to 8, characterized in that the means (190) for generating a setpoint is clean issue a safety instruction to an actuating system of a disconnection device d urgency of the or each link.

10. - System according to any one of claims 1 to 9, characterized in that, said link being a fluid transfer line, the means (190) for generating a set is clean to issue a safety instruction to a actuating system of the pumps and valves allowing the flow of fluid in the or each pipe.

1 1. - System according to any one of claims 1 to 10, characterized in that it is clean issue a positioning instruction to a dynamic positioning system of the first structure and / or the second structure.

12. - Method for real-time control of at least one link (20; 1021 to 1024) between first and second structures (10, 12), at least the second structure being a floating structure, the or each link being clean to be connected by a first end to the first structure and by its second end to the second structure, characterized in that it comprises the steps of: acquire kinematic variables of the movement of the second end of the or each link with respect to its first end,

- Generate a setpoint according to the one or more quantities determined.