WO2024072211A1

WO2024072211A1 - Non-contact motion compensation of suspended loads

Info

Publication number: WO2024072211A1
Application number: PCT/NL2023/050447
Authority: WO
Inventors: Peter Christiaan MEIJERS; Andrey Vladimirovich METRIKINE
Original assignee: Technische Universiteit Delft
Priority date: 2022-09-29
Filing date: 2023-08-31
Publication date: 2024-04-04

Abstract

Method of non-contact motion compensation of a suspended load (6) having a dynamic position, measuring and controlling said dynamic position using electro-magnetic devices, and controlling said dynamic position. The invention is in particular suited for suspended loads on a floating vessel, which floating vessels is subjected to various sorts of motion that influence the suspended load. An example of such a suspended load is a part of a wind turbine.

Description

NON-CONTACT MOTION COMPENSATION OF SUSPENDED LOADS

FIELD OF THE INVENTION

The present invention is in the field of suspended loads having a dynamic position, measuring and controlling said dynamic position using electro-magnetic devices, and controlling said dynamic position. The invention is in particular suited for suspended loads on a floating vessel, which floating vessels is subjected to various sorts of motion that influence the suspended load. An example of such a suspended load is a part of a wind turbine.

BACKGROUND OF THE INVENTION

Floating vessels, in particular ships or lifting vehicles, may be prone to various sorts of motion. These motions can be divided into translational motions, such as surge, sway, and heave, and rotational type of motions, such as roll, pitch, and yaw. These latter motions can be defined around the three virtual axes in a ship, the longitudinal, transverse, and vertical axis. The movements around them are known as roll, pitch, and yaw respectively. A tilting rotation of a vessel around its longitudinal axis is referred to as roll. An offset or deviation from normal on this axis is typically experienced, at least to some extent. Heel refers to an offset that may be intentional or may be expected, as caused by wind pressure on sails, turning, or other crew actions. The rolling motion towards a steady state (or list) angle due to the ship's own weight distribution is referred in marine engineering as heel. List may be an unintentional or unexpected offset, as caused by flooding, battle damage, shifting cargo, etc. An up/down rotation of a vessel about its transverse axis is referred to as pitch. An offset or deviation from normal on this axis may be referred to as trim or out of trim. A turning rotation of a vessel about its vertical axis is referred to as yaw. An offset or deviation from normal on this axis may be referred to as deviation or set. This is referred to as the heading of the boat relative to the earth magnetic field. A linear longitudinal (front/back or bow/stem) motion imparted by maritime conditions, usually head or following seas, or by accelerations imparted by the propulsion system is referred to as surge. A linear transverse (side-to-side or port-starboard) motion is referred to as sway. This motion is generated directly either by the water and wind motion, particularly lateral wave motion, exerting forces against the hull or by the ship's own propulsion; or indirectly by the inertia of the ship while turning. This movement can be compared to the vessel's lateral drift from its course. Finally, a linear vertical (up/down) motion is referred to as heave; excessive downward heave can swamp a ship [see https; orgAviki/Ship . motion s] .

In order to compensate for the various forms of motion first of all the motion of a ship may be controlled. Such can be done actively or passively, or both. An anchor would provide a passive control, but using an anchor is quite often not possible, time consuming, and does not provide sufficient control. With active control much better control can be achieved. With state-of-the-art control ship movement in a translational direction can under reasonable conditions be controlled within a few meters, typically within one meter. Rotational movement is more difficult to control.

In the coming years, the number of newly build offshore wind farms in Europe will increase significantly. Currently, each wind turbine is assembled on site such as by using a jack-up crane vessel, which can raise itself out of the water by means of extensible legs. Above the water line, the influence of currents and waves on the ship's motion is eliminated, creating a stable platform for lifting operations. However, raising the vessel from the water is a time-costly procedure and it is impossible in deeper waters. In an alternative, the installation is performed by a floating heavy lifting vessel. During the assembly of a wind turbine, heavy components are lifted by an on-board crane. The vessel uses dynamic positioning to keep itself at the same location regardless the sea's and wind’s impact on the vessel, such as a current. However, certain motions, such as wave-induced vessel motions, are mechanically transferred to the load that is suspended in the crane, creating undesired swinging motions. Currently, mechanical restrictions are imposed onto the suspended loads, such as tugger lines (tensioned steel cables), which are used to limit these motions to within a reasonable band. Connecting these additional cables to the load is time consuming and the physical contact poses a liability for the contractor in case the load is damaged due to the lines. In addition the cables attached to the load control the motion of the load typically only partly. Some motions of the load (mainly up-down, i.e. heave) can be compensated in particular using a device attached between the crane hook and the load. Attaching and removing cables to/from the load is time consuming and requires people to physically be close to the attachment point. Getting people to such locations can be dangerous. The cables might damage the load in addition. So great care is required.

In line with the above apparatuses and methods are available that compensate motion by contacting the suspended load, directly or indirectly. For instance, based on predicted motion of a ship an apparatus suspending the load, such as a crane, may be actively manipulated to compensate for the predicted motion, such as by extending a boom, correcting a knuckle angle, correcting a luff angle, by activating a winch, or the like. Motion compensation can be achieved in a direct contact manner, such as mechanically, or in an indirect contact manner, such as by applying a force to a tow or cable or the like.

Incidentally, US 5 919 022 A can be mentioned. The document recites an intermodal container positioning system for facilitating loading or positioning of intermodal containers via overhead crane or the like, wherein there is provided an array of electromagnets in various, alternative positions in the vicinity of the container, such that the electromagnets may be selectively utilized to engage adjacent structure, or other containers, in the vicinity of the container lock down or storage area, in such a manner as to manipulate the position of the container, to align same with other containers, a container holding area, lock down area, or the like. A sensor array to monitor the position of the container relative to other containers or structures, or relative to lock down hardware, may be present, so as to vary the force on selective magnets in the array to manipulate the container, positioning same in the appropriate alignment for securing and/or parking. This sensor array may further compensate for wind, cable sway, or other factors which contribute to the lack of control of a container from a crane.

The present invention relates to an improved suspended load device, which overcomes one or more of the above disadvantages, without jeopardizing functionality and advantages.

SUMMARY OF THE INVENTION

The present invention relates in a first aspect to a method of non-contact motion com- pensation of a suspended load, in a second aspect to a non-contact device for motion compensation of electro-magnetically influenceable suspended loads, such as steel load, and in a third aspect to a computer program comprising instructions, the instructions causing the computer to carry out the step of controlling motion. In an example it comprises an array of non-contact actuators, i.e., electromagnets and/or compressed fluid jets, such as air jets, a device to comply with the vessel motions, e.g., a robotic arm or a drone, at least one motion sensor to measure the vessel motion, and a controller, such as a PID, a fuzzy logic controller, etc. For better understanding it is noted that a position sensor relates to a sensor that detects an object's position. A position sensor may indicate the absolute position of the object (its location) or its relative position (displacement) in terms of linear travel, rotational angle or three-dimensional space. The present invention, however, uses at least one motion sensor, that is, detecting and quantifying a change in position, as well as relative motion, such as in terms of velocity of a sensed object. In physics, motion is the phenomenon by which an object changes its position with respect to time. Motion may mathematically be described in terms of displacement, distance, velocity, acceleration, speed, and frame of reference to an observer or sensor, measuring the change in position of the body relative to that frame with a change in time. Quantifying motion therefore is considered much more difficult that measuring a position. The motion-compensation device may be mounted on the vessel and the actuator array is attached to the moving end of this device. The sensors provide the input for the controller to position the actuators at a safe distance from the load and to impose a correct force in particular to neutralize the motion of the load with respect to the desired location, e.g., a foundation pile fixed in the seabed, a barge, another vessel, and a foundation of a floating wind turbine. A motion sensor is typically configured to measure deviations of a suspended load with an accuracy better than 1 cm, typically withing 1 mm, to obtain images at a frequency of > 10 Hz, typically at 50 Hz. As no cables have to be attached, the time needed to install the load is limited, reducing cost. Moreover, anything which is attached to the load creates a risk to damage the payload. Therefore, this non-contact solution reduces the risk for the contractor to damage the load. It is noted that floating installations currently have very limited operational windows as the wave-induced motions are relatively large even using cables. With this new system, floating installation becomes a much more feasible alternative to jack-up vessel, and the window of operation is increased. The present device and method provide an opportunity to replace to state-of-the-art installation methods, i.e. jack-up vessels. In addition the present system may be used many times. This invention may use electromagnets to compensate a suspended load excited by crane tip motions in combination with a device to make the actuator comply to the ship motions (e.g. a robotic arm). This is quite a specific combination and thus easily detected.

In a first aspect, the present invention relates to a method of non-contact motion compensation of a suspended load comprising providing a non-contact suspended-load-motion-sensor, such as a laser distance sensor, an ultrasonic distance sensor, and an optical tracking sensor, such as a (3D) camera, the motion sensor configured to sense motion of the suspended load in at least a plane perpendicular to a central vertical axis of the suspended load and to provide motion sensor output to at least one controller, providing at least one non-contact actuator configured to apply a force to the suspended load in at least a plane perpendicular to a central vertical axis of the suspended load, providing the at least one controller, the at least one controller configured to process the motion sensors output, and configured to activate the at least one actuator.

In a second aspect the present invention relates to a device for non-contact motion compensation of a suspended load comprising a suspended load motion sensor, the motion sensor configured to sense motion of the suspended load in at least a plane perpendicular to a central vertical axis of the suspended load and to provide motion sensor output to at least one controller, at least one actuator configured to apply a force to the suspended load in at least a plane perpendicular to a central vertical axis of the suspended load, and the at least one controller configured to process the motion sensors output, and configured to activate the at least one actuator.

In a third aspect the present invention relates to a computer program comprising instructions, the instructions causing the computer to carry out the following steps: controlling a non-contact sus- pended-load-motion-sensor, sensing motion with the motion sensor of the suspended load in at least a plane perpendicular to a central vertical axis of the suspended load and providing motion sensor output to at least one controller, applying a force to the suspended load with at least one non-contact actuator in at least a plane perpendicular to a central vertical axis of the suspended load, and optionally providing the at least one controller, the at least one controller configured to process the motion sensors output, and configured to activate the at least one actuator measuring motion of the floating vessel for a first time period, wherein motion comprises a horizontal motion relative to a fixed location on the surface of earth and relative to the earth gravitational field, and is further selected from at least one of motion from roll, from pitch, from yaw, from surge, from sway, and from heave, therewith obtaining vessel motion data; b) measuring at least one performance parameter of the a least one non-contact actuator, wherein the performance parameter of the actuator is selected from a deviation from a predefined standard performance parameter, such as the inertia, speed, acceleration, or position of the actuator, from a coupling force of the actuator on the load, and the response time of the actuator to implement a control signal; c) generating a predicted motion model of the vessel for a subsequent second time period from the vessel motion data, and generating a predicted performance parameter of the actuator for the second time period; d) generating a control algorithm for the actuator to effect a predetermined response during the second time period using the predicted motion model and the predicted performance parameter; e) determining a first correction factor from differences between motion data and the predicted motion model and a second correction factor from differences between the actuator performance parameter and predicted performance parameter; f) repeating steps a e iteratively utilising the first and second correction factors, and controlling the at least one actuator and optionally the moveable arm therewith compensating for the measured motion of the floating vessel.

With the present method and device, one may consider that the suspended load motion is decoupled from that to which it is attached, e.g. from a vessel or from crane, such that relative to a second location (that is the position of the fundament etc. to which the suspended load is to be transferred, or to a second vessel etc) virtually no motion occurs, or at least within acceptable limits.

Controlling the motion of a load suspended from a vessel to decouple it from the vessel motion may comprise various steps, including measuring motion, providing feedback and/or feedforward control, generating a model of motion, providing an algorithm, and controlling the at least one actuator accordingly. The actuator may be the present non-contact actuator. The performance parameter of the actuator may be a deviation from a predefined standard performance parameter such as the inertia, speed, acceleration or position of the actuator, the coupling force on the actuator from the load, or the response time of the actuator to implement a control signal.

Thereby the present invention provides a solution to one or more of the above-mentioned problems.

Advantages of the present description are detailed throughout the description. References to the figures are not limiting, and are only intended to guide the person skilled in the art through details of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates in a first aspect to the method of non-contact motion compensation of a suspended load according to claim one.

In an exemplary embodiment of the present method the at least one actuator is provided on at least one moveable arm, wherein the at least one controller is configure to control a position of the at least one actuator relative to the suspended load, in particular to maintain the position at a substantially equal distance of the suspended load, in particular at a distance of < 5 cm, such as 0.5- 2 cm.

In an exemplary embodiment the present method may further comprise providing at least one suspended load position sensor configured to detect the position of the suspended load relative to the at least one actuator, in particular selected from at least one of a non-contact electromagnetic field sensor, an ultrasonic sensor, and an optical sensor, in particular an optical tracking system (e.g. 3D camera) such as using IR or laser light, more in particular at least one sensor configured to sense motion of the suspended load in at least the plane perpendicular to the central vertical axis of the suspended load, and in particular wherein the at least one sensor is configured to provide output to the at least one controller, the at least one controller configured to process the at least one sensor output, in particular wherein the at least one controller is configured to determine a position and motion of the suspended load in a feedforward loop.

In an exemplary embodiment of the present method the at least one actuator is selected from an electromagnetic actuator, and a fluid jet, such as a compressed air jet or a waterjet.

In an exemplary embodiment of the present method the at least one actuator is provided in at least one array, in particular at least one array of n by m actuators, wherein ne [2-50] and me [1-10], more in particular wherein ne [3-20] and me [2-8], even more in particular wherein ne [4-10] and me [3-5], wherein in the at least one array at least one first actuator is provided under an angle in a horizontal plane with respect to at least one second actuator, in particular under an angle of 10-90 degrees, such as 30-60 degrees. In an exemplary embodiment of the present method the at least one actuator is provided in the plane perpendicular to the central vertical axis of the suspended load, in particular wherein the at least one actuator is provided at a substantially equal distance from the central vertical axis, such as in a circle or part thereof, the circle having a centre substantially overlapping with the central vertical axis.

In an exemplary embodiment of the present method the at least one moveable arm is a robotic arm, in particular a robotic arm providing three or more degrees of freedom, such as 6 degrees of freedom (x,y,z, c|)- and 0-rotations, and arm -rotation).

In an exemplary embodiment of the present method the method is applied on a floating vessel, in particular wherein motion of the vessel is controlled and limited, more in particular wherein horizontal movement of the vessel is controlled and limited, and optionally wherein sway, surge and yaw of the vessel is controlled and limited.

In an exemplary embodiment the present method may further comprise measuring motion of the floating vessel for a first time period, wherein motion comprises a horizontal motion relative to a fixed location on the surface of earth and relative to the earth gravitational field, and is further selected from at least one of motion from roll, from pitch, from yaw, from surge, from sway, and from heave, therewith obtaining vessel motion data; b) measuring at least one performance parameter of the a least one non-contact actuator, wherein the performance parameter of the at least one non-contact actuator is selected from a deviation from a predefined standard performance parameter, such as the inertia, speed, acceleration, or position of the actuator, from a coupling force of the actuator on the load, and the response time of the actuator to implement a control signal; c) generating a predicted motion model of the vessel for a subsequent second time period from the vessel motion data, and generating a predicted performance parameter of the actuator for the second time period; d) generating a control algorithm for the actuator to effect a predetermined response during the second time period using the predicted motion model and the predicted performance parameter; e) determining a first correction factor from differences between motion data and the predicted motion model and a second correction factor from differences between the actuator performance parameter and predicted performance parameter; f) repeating steps a e iteratively utilising the first and second correction factors, and controlling the at least one actuator and optionally the moveable arm therewith compensating for the measured motion of the floating vessel.

In an exemplary embodiment of the present method the suspended load is at least a part of an off-shore wind turbine, in particular all parts of the pillar of an off-shore wind turbine.

In an exemplary embodiment of the present method the suspended load is provided with a protection, such as clamp, or jacket.

In an exemplary embodiment of the present method the method is performed under local wind conditions of up to 10 m/s, in particular of up to 8 m/s, more in particular of up to 5.5 m/s.

In an exemplary embodiment of the present method the force is applied to the suspended load substantially at a lower end or close to the lower end of the suspended load. In an exemplary embodiment of the present device each actuator individually is configured to provide a force IN- 10 kN, in particular 10N-5 kN, more in particular 100N-2 kN.

In an exemplary embodiment of the present device each actuator individually is configured to provide an adaptable force, In an exemplary embodiment of the present device each actuator individually comprises at least one coil.

In an exemplary embodiment of the present device each actuator individually comprises at least one magnetizable core.

The invention is further detailed by the accompanying figures and examples, which are exemplary and explanatory of nature and are not limiting the scope of the invention. To the person skilled in the art it may be clear that many variants, being obvious or not, may be conceivable falling within the scope of protection, defined by the present claims.

SUMMARY OF FIGURES

Figure la shows principles of the present device.

Fig. 2 shows the present control loop.

Fig. 3 shows an experimental set-up.

Fig. 4 shows experimental results. Figs. 5-7 show further details thereof.

DETAIEED DESCRIPTION OF FIGURES

1 array of non-contact actuators

2 robotic arm

3 controller and sensor system

3a sensor

3b controller

4 floating installation vessel

5 crane

6 steel suspended load

7 fixed foundation pile

Figure 1 shows a floating crane vessel (4,5) lifting a load (6) to place the load on top a foundation pile (7). The wave-induced motion of the load is compensated by the present device, which exists of an array of non-contact actuators (1) mounted on a robotic arm (2). The position and strength of the non-contact actuator is controlled by a unit (3), which collects motion and position data with sensors.

Figure 2 shows a realization of the control loop of the device. Environmental data (wave, wind, and vessel motion) is processed via a model of the vessel to compute the desired position of the load with respect to the final position. This desired position is fed into the control loop, which contains a Proportional-Derivative controller. A mathematical model for the non-linear actuator force is used to linearize the controller action. The output of the controller is an actuator signal for the non-contact actuator, creating a force that acts on the load. The feedback loop is closed by measurements of the position of the load obtained by non-contact position sensors.

Figure 3 shows a basic experimental realization of the present device, comprising of a sus- pended load, a laser distance sensor ALTHEN FDRF603-100, an electromagnet, and a PD-control- ler; further including a moving crane tip, that is, a moving suspension point, and a robotic arm, comprising a contact-less sensor and magnetic actuator. The motion of the load is restricted in a plane, and its direction is indicated by x.

Figure 4 shows a time trace of the desired motion imposed and the measured motion of the load, when no motion of the suspension point is prescribed. The excellent correspondence of the two lines indicate that the controller is able to control the motion of the load fully.

Figure 5 : The time signal of the movement of the suspension point used for each demonstration presented in Figure 6 and 7. The signal was calculated using a realistic wave spectrum and ship response. The motion was then scaled to the dimensions in the lab in terms of amplitude and frequency, creating a realistic excitation of the system.

Figure 6: A demonstration of the system in which the motion of the mass of completely removed. The first 9 seconds the system is not allowed to be active. Then it is, and it brings the mass to a rapid stop. Also shown for reference is the motion of the mass when no motion compensation is applied.

Figure 7 : Same as Figure 6, but now with the added difficulty that the mass must now follow a prescribed motion. This clearly demonstrates how this system deals with prescribed motion.

The invention although described in detailed explanatory context may be best understood in conjunction with the accompanying figures.

It should be appreciated that for commercial application it may be preferable to use one or more variations of the present system, which would similar be to the ones disclosed in the present application and are within the spirit of the invention.

Claims

1. A method of non-contact motion compensation of a suspended load (6) comprising providing at least one non-contact suspended-load-motion-sensor (3a), the at least one motion sensor configured to sense motion of the said suspended load in at least a plane perpendicular to a central vertical axis of the suspended load and to provide motion sensor output to at least one controller, providing at least one non-contact actuator (1) configured to apply a force to the said suspended load in at least a plane perpendicular to a central vertical axis of the said suspended load, providing the at least one controller (3b), the at least one controller configured to process the at least one motion sensors output, and configured to activate the at least one actuator.

2. The method according to claim 1, wherein the at least one actuator is provided on at least one moveable arm, wherein the at least one controller is configured to control a position of the at least one actuator relative to the suspended load, in particular to maintain the position at a substantially equal distance of the suspended load, in particular at a distance of < 5 cm, such as 0.5-2 cm.

3. The method according to any of claims 1-2, further comprising providing at least one suspended load position sensor configured to detect the position of the suspended load relative to the at least one actuator, in particular selected from at least one of a noncontact electromagnetic field sensor, an ultrasonic sensor, and an optical sensor, such as using IR or laser light, more in particular at least one sensor configured to sense motion of the suspended load in at least the plane perpendicular to the central vertical axis of the suspended load, and in particular wherein the at least one sensor is configured to provide output to the at least one controller, the at least one controller configured to process the at least one sensor output, in particular wherein the at least one controller is configured to determine a position and motion of the suspended load in a feedforward loop.

4. The method according to any of claims 1-3, wherein the at least one actuator is selected from an electromagnetic actuator, and a fluid jet, such as a compressed air jet or a waterjet.

5. The method according to any of claims 1-4, wherein the at least one actuator is provided in at least one array, in particular at least one array of n by m actuators, wherein ne [2-50] and me [1-10], more in particular wherein ne [3-20] and me [2-8], even more in particular wherein ne [4-10] and me [3-5], wherein in the at least one array at least one first actuator is provided under an angle in a horizontal plane with respect to at least one second actuator, in particular under an angle of 10-90 degrees, such as 30-60 degrees.

6. The method according to any of claims 1-5, wherein the at least one actuator is provided in the plane perpendicular to the central vertical axis of the suspended load, in particular wherein the at least one actuator is provided at a substantially equal distance from the central vertical axis, such as in a circle or part thereof, the circle having a centre substantially overlapping with the central vertical axis.

7. The method according to any of claims 1-6, wherein the at least one moveable arm is a robotic arm, in particular a robotic arm providing three or more degrees of freedom, such as 6 degrees of freedom (x,y,z, c|)- and 0-rotations, and arm -rotation).

8. The method according to any of claims 1-7, wherein the method is applied on a floating vessel, in particular wherein motion of the vessel is controlled and limited, more in particular wherein horizontal movement of the vessel is controlled and limited, and optionally wherein sway, surge and yaw of the vessel is controlled and limited.

9. The method according to claim 8, further comprising measuring motion of the floating vessel for a first time period, wherein motion comprises a horizontal motion relative to a fixed location on the surface of earth and relative to the earth gravitational field, and is further selected from at least one of motion from roll, from pitch, from yaw, from surge, from sway, and from heave, therewith obtaining vessel motion data; b) measuring at least one performance parameter of the a least one non-contact actuator, wherein the performance parameter of the at least one non-contact actuator is selected from a deviation from a predefined standard performance parameter, such as the inertia, speed, acceleration, or position of the actuator, from a coupling force of the actuator on the load, and the response time of the actuator to implement a control signal; c) generating a predicted motion model of the vessel for a subsequent second time period from the vessel motion data, and generating a predicted performance parameter of the actuator for the second time period; d) generating a control algorithm for the actuator to effect a predetermined response during the second time period using the predicted motion model and the predicted performance parameter; e) determining a first correction factor from differences between motion data and the predicted motion model and a second correction factor from differences between the actuator performance parameter and predicted performance parameter; f) repeating steps a e iteratively utilising the first and second correction factors, and controlling the at least one actuator and optionally the moveable arm therewith compensating for the measured motion of the floating vessel.

10. The method according to any of claims 1-9, wherein the suspended load is at least a part of an off-shore wind turbine, in particular all parts of the pillar of an off-shore wind turbine, and/or wherein the suspended load is provided with a protection, such as clamp, or jacket.

11. The method according to any of claims 1-10, wherein the method is performed under local wind conditions of up to 10 m/s, in particular of up to 8 m/s, more in particular of up to 5.5 m/s.

12. The method according to any of claims 1-11, wherein the force is applied to the suspended load substantially at a lower end or close to the lower end of the suspended load.

13. A device for non-contact motion compensation of a suspended load comprising a suspended load motion sensor (3a), the motion sensor configured to sense motion of the said suspended load in at least a plane perpendicular to a central vertical axis of the suspended load and to provide motion sensor output to at least one controller (3b), at least one actuator (1) configured to apply a force to the said suspended load in at least a plane perpendicular to a central vertical axis of the suspended load, and the at least one controller (3b) configured to process the motion sensors output, and configured to activate the at least one actuator (1).

14. The device for non-contact motion compensation of a suspended load according to claim 13, wherein each actuator individually is configured to provide a force IN- 10 kN, in particular 10N-5 kN, more in particular 100N-2 kN, and/or wherein each actuator individually is configured to provide an adaptable force, and/or wherein each actuator individually comprises at least one coil, and/or wherein each actuator individually comprises at least one magnetizable core.

15. Computer program comprising instructions, the instructions causing the computer to carry out the following steps controlling a non-contact suspended-load-motion-sensor (3a), sensing motion with the motion sensor of the said suspended load in at least a plane perpendicular to a central vertical axis of the said suspended load and providing motion sensor output to at least one controller (3b), applying a force to the said suspended load with at least one non-contact actuator (1) in at least a plane perpendicular to a central vertical axis of the said suspended load, and optionally providing the at least one controller, the at least one controller configured to process the motion sensors output, and configured to activate the at least one actuator measuring motion of the floating vessel for a first time period, wherein motion comprises a horizontal motion relative to a fixed location on the surface of earth and relative to the earth gravitational field, and is further selected from at least one of motion from roll, from pitch, from yaw, from surge, from sway, and from heave, therewith obtaining vessel motion data; b) measuring at least one performance parameter of the a least one non-contact actuator, wherein the performance parameter of the actuator is selected from a deviation from a predefined standard performance parameter, such as the inertia, speed, acceleration, or position of the actuator, from a coupling force of the actuator on the load, and the response time of the actuator to implement a control signal; c) generating a predicted motion model of the vessel for a subsequent second time period from the vessel motion data, and generating a predicted performance parameter of the actuator for the second time period; d) generating a control algorithm for the actuator to effect a predetermined response during the second time period using the predicted motion model and the predicted performance parameter; e) determining a first correction factor from differences between motion data and the predicted motion model and a second correction factor from differences between the actuator performance parameter and predicted performance parameter; f) repeating steps a e iteratively utilising the first and second correction factors, and controlling the at least one actuator and optionally the moveable arm therewith compensating for the measured motion of the floating vessel.

16. A device or method comprising at least one element according to any of the claims 1-15 and optionally an element from the description.