WO2019193398A1

WO2019193398A1 - An actuator for a heave compensator with an increased stroke length

Info

Publication number: WO2019193398A1
Application number: PCT/IB2018/052350
Authority: WO
Inventors: Tord Martinsen; Tomi KERÄNEN
Original assignee: Safelink As
Priority date: 2018-04-05
Filing date: 2018-04-05
Publication date: 2019-10-10

Abstract

An actuator 10 for a heave compensator 100 comprising, a first actuator piston 11 connected to a first actuator piston rod 11a and configured within a first cylinder 12. The first actuator piston 11 is adapted for reciprocation within the first cylinder 12. A second actuator piston 13 is configured within at least one second cylinder 14, wherein the at least one second cylinder 14 is configured around the first cylinder 12 and the second actuator piston 13 is adapted for reciprocation within the at least one second cylinder 14. A second actuator piston rod 13a connected to the second actuator piston 13, wherein the second actuator piston 13 is adapted to displace in a direction opposite to the displacement of the first actuator piston 11 to achieve increased stroke length of the actuator 10.

Description

AN ACTUATOR FOR A HEAVE COMPENSATOR WITH AN INCREASED

STROKE LENGTH

TECHNICAL FIELD

[0001] Present disclosure generally relates to the field of hydraulic and pneumatic automation. Particularly, but not exclusively, the disclosure relates to a heave compensator. Further, embodiments of the present disclosure, discloses a heave compensator to compensate heave motion experienced during hoisting or lifting of a payload experienced by an offshore vessel in an offshore environment.

BACKGROUND OF THE DISCLOSURE

[0002] Conventionally, transportation and positioning of heavy structures to and/or from a water-borne vessel may be perfonned by employing a crane. The crane may be positioned on a barge, proximal to the water-borne vessel, or may be provided on the water-borne vessel. In general, the crane may be provisioned with a maneuverable jib member, where the jib member may be connected to the crane at a boom point. Further, the jib member may be pivotally maneuvered in a horizontal and/or in a vertical direction, to displace the heavy structures in and out-from the water-borne vessel.

[0003] However, the water-borne vessel may traverse through regions having unfavorable weather conditions and/or the barge may be si tuated in a location which may have a hostile weather condition. Due to the unfavorable weather conditions, the waterborne vessel and the barge may be influenced by swells and winds at the sea, thereby, imparting irregular movements during displacement of the heavy structures. These swells and winds may greatly affect the crane at the boom point, whereby affecting operation of the jib member during displacement of the heavy structures. The irregular movement of the jib member may result in a deviation in alignment of the heavy structures, which then produces improper positioning of the heavy structures from a preferred alignment. In addition, the deviation in alignment of the heavy structures may also occur due to violent sway of the water-borne vessel, during traversing at sea. [0004] Additionally, in order to lift heavy loads of the water-borne vessel, oversize emplacements are required to be installed on the deck of the water-borne vessel. Such emplacements will be bulky and would lead to space constraints as bigger hydraulic and pneumatic tanks are required to supply additional volume of fluid and gas to the heave compensator. Moreover, in conventional heave compensators, the stroke length of the actuator is shorter and hence the shorter stroke actuator may only be able to compensate for smaller waves. However, in severe weather conditions, such conventional actuators with shorter stroke lengths may not be capable of handling bigger waves. Moreover, conventional systems that come equipped with shorter stoke length actuators have limited operational capabilities in terms of reaching the surface of the water.

[0005] Conventionally, efforts have been made to develop a heave compensator, as shown in Figure. 1, which typically is a crane mounted active heave compensator. The conventional heave compensator, in general, is a wire rope driven compensator and is equipped with large jib members. The problems associated with such compensators are including, but not limited to, structural immobility, wire rope fatigue, insufficient splash zone crossing performance, space constraints, bulky emplacements, high power demand for operation, lack of models for heavy lifts, and the like.

[0006] The present disclosure is directed to overcome one or more limitations stated abo ve.

[0007] The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgment or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

SUMMARY OF THE DISCLOSURE

[0008] One or more shortcomings of the prior art are overcome by a system and a method as claimed and additional advantages are provided through the system and the method as claimed in the present disclosure. Additional features and advantages are realized through the techni ques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

[0009] One non-limiting embodiment of the present disclosure relates to an actuator for a heave compensator. The actuator further comprises a first actuator piston connected to a first actuator piston rod which is configured within a first cylinder. The first actuator piston is adapted for reciprocation within the first cylinder. A second actuator piston is configured within at least one second cylinder, wherein the at least one second cylinder is configured around the first cylinder and the second actuator piston is adapted for reciprocation within the at least one second cylinder. Further, a second actuator piston rod is connected to the second actuator piston, wherein tile second actuator piston is adapted to displace in a direction opposite to the displacement of the first actuator piston to achieve increased stroke length of the actuator.

[0010] In an embodiment of the present disclosure, the actuator comprises the first cylinder which is compartmentalized to a first chamber on the first actuator piston side and a first fluid chamber on the first actuator rod side. [001 1] In an embodiment of the present disclosure, the actuator further includes the at least one second cylinder which is compartmentalized into a second chamber on the second actuator piston side and a second fluid chamber on the second actuator rod side. [0012] In an embodiment of the present disclosure, the actuator comprising a connector ring connected to the second actuator piston rod is adapted to displace with the second actuator piston.

[0013] In an embodiment of the present disclosure, the actuator comprising one or more sensors, provided on each of the first actuator piston rod and tile second actuator piston rod wherein the one or more sensors determine position of the first actuator piston rod and the second actuator piston rod and provides position parameters to a control unit.

[0014] In another non-limiting embodiment of the present disclosure, a heave compensator is disclosed. The heave compensator comprises an actuator with a first actuator piston connected to a first actuator piston rod which is configured within a first cylinder. The first actuator piston is adapted for reciprocation within the first cylinder. A second actuator piston is configured within at least one second cylinder, wherein the at least one second cylinder is configured around the first cylinder and the second actuator piston is adapted for reciprocation within the at least one second cylinder. Further, a second actuator piston rod is connected to the second actuator piston, wherein the second actuator piston is adapted to displace in a direction opposite to the displacement of the first actuator piston to achieve increased stroke length of the actuator. The heave compensator further comprises, a first accumulator and a second accumulator fluidly connected to the actuator to transmit fluid and gas respectively for operation of the actuator. At least one booster unit is fluidly connected to the first accumulator and the second accumulator for discharging boosted gas into the first accumulator and the second accumulator.

[0015] In an embodiment of the present disclosure, the first accumulator comprising a first accumulator piston, a second accumulator piston and a third accumulator piston adapted for reciprocation within the first accumulator upon displacement of the first actuator piston.

[0016] In an embodiment of the present disclosure, the second accumul ator comprising a fourth accumulator piston, a fifth accumulator piston and a sixth accumulator piston adapted for reciprocation within the second accumulator upon displacement of the second actuator piston.

[0017] In an embodiment of the present disclosure, the second accumulator piston is connected to a second accumulator piston rod and adapted for reciprocation within a first fluid compartment. [0018] In an embodiment of the present disclosure, the third accumulator piston is connected to a third accumulator piston rod and adapted for reciprocation within a second fluid compartment. [0019] In an embodiment of the present disclosure, the first accumulator piston is connected to the second accumulator piston rod on one side and is connected to the third accumulator piston rod on other side.

[0020] In an embodiment of the present disclosure, the fourth accumulator piston is connected to a fourth accumulator piston rod and adapted for reciprocation within a third fluid compartment.

[0021] In an embodiment of the present disclosure, the fifth accumulator piston is connected to a fifth accumulator piston rod and adapted for reciprocation within a fourth fluid compartment.

[0022] In an embodiment of the present disclosure, the sixth accumulator piston is connected to the fourth accumulator piston rod on one side and is connected to the fifth accumulator piston rod on other side.

[0023] In another non-limiting embodiment of the present disclosure, a control unit is configured to determine position of the first actuator piston rod and the second actuator piston rod wherein the one or more sensors is configured on the first actuator piston rod and the second actuator piston rod generates a position parameter si gnal to the control unit. Further, upon displ acement of the first actuator piston and the second actuator piston fluid from a first fluid chamber transfers to a seventh fluid chamber and selectively transfers the fluid from the second fluid chamber to an eighth fluid chamber upon displacement of the first actuator piston and the second actuator piston respectively. Supply of gas from a first gas tank and a second gas tank to the first accumulator and the second accumulator occurs upon displacement of the first accumulator piston and a sixth accumulator piston respectively. The control unit further determines temperature of a surrounding media of the actuator and pressure of the fluid and the gas in the first accumulator, and the second accumulator. Further, the control imit operates at least one booster unit for supplying boosted gas to the first accumulator and the second accumulator, wherein the at least one booster unit is operated to compensate the volume of the gas.

[0024] In yet another non- limiting embodiment of the present disclosure, a method of operating a heave compensator is disclosed. The method comprising channeling a fluid flow from a first fluid chamber to a seventh fluid chamber and channeling the fluid flow from a second fluid chamber to an eighth fluid chamber, upon displacement of the first actuator piston and the second actuator piston in a passive mode. Channeling the fluid in-between a third fluid chamber to a fourth fluid chamber and vice versa by adjusting fluid pressure, upon displacement of the second accumulator piston and channeling the fluid in-between a fifth fluid chamber to a sixth fluid chamber and vice versa by adjusting fluid pressure, upon displacement of the third accumulator piston in the passive mode. Regulating the fluid flow from the first fluid chamber to the seventh fluid chamber and regulating the fluid flow from the second fluid chamber to the eighth fluid chamber, upon displacement of the first actuator piston and the second actuator piston in an active mode. in the passive mode. Regulating the fluid flow in-between the third fluid chamber to the fourth fluid chamber and vice versa upon displacement of the second accumulator . Regulating the fluid from the sixth fluid chamber to the fifth fluid chamber and vice versa, upon displacement of the sixth accumulator piston in the active mode. [0025] In an embodiment of the present disclosure, the control unit determines a position of an actuator rod and a pressure of the fluid and the gas in the actuator, wherein the control unit operates the actuator between the passive mode and the active mode, based on data received from the one or more sensors. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0026] The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which: [0027] Figure 2 is a schematic diagram of a water-borne vessel employing a heave compensator for lifting a payload, in accordance with one embodiment of the present disclosure.

[0028] Figure 3 is a schematic diagram of an actuator of tile heave compensator at no stroke condition, in accordance with one embodiment of the present disclosure.

[0029] Figure 4 is a schematic diagram of the actuator of the heave compensator of figure

3 at mid-stroke condition, in accordance with one embodiment of the present disclosure.

[0030] Figure 5 is a schematic diagram of the actuator of the heave compensator of fi gure

3 at full-stroke condition, in accordance with one embodiment of the present disclosure. [0031] Figure 6 is a schematic diagram of the actuator of the heave compensator in an alternate configuration at no stroke condition, in accordance with one embodiment of the present disclosure.

[0032] Figure 7 is a schematic diagram of the actuator of the heave compensator of figure

6 at mid-stroke condition, in accordance with one embodiment of the present disclosure. [0033] Figure 8 is a schematic diagram of the actuator of the heave compensator of fi gure 6 at full stroke condition, in accordance with one embodiment of the present disclosure.

[0034] Figure 9 is a schematic diagram of the actuator of the heave compensator in yet another alternate configuration at no stroke condition, in accordance with one embodiment of the present disclosure.

[0035] Figure 10 is a schematic diagram of the actuator of the heave compensator of figure

9 at mid-stroke condition, in accordance with one embodiment of the present disclosure.

[0036] Figure 11 is a schematic diagram of the actuator of the heave compensator of figure

9 at full stroke condition, in accordance with one embodiment of the present disclosure.

[0037] Figure 12 is a schematic diagram of the actuator of the heave compensator in yet another alternate configuration at no stroke condition, in accordance with one embodiment of the present disclosure. [0038] Figure 13 is a schematic diagram of the actuator of the heave compensator of figure

12 at mid-stroke condition, in accordance with one embodiment of the present disclosure.

[0039] Figure 14 is a schematic diagram of the actuator of the heave compensator of figure

12 at full stroke condition, in accordance with one embodiment of the present disclosure.

[0040] The figures depict embodiments of the disclosure for purposes of illustration only.

One skilled in the art will readily recognize from the following description that alternative embodiments of the system and method illustrated herein may be employed without departing from the principles of the disclosure described herein. DETAILED DESCRIPTION

[0041] While the embodiments in the disclosure are subject to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the figures and will be described below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, tile disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.

[0042] The terms“comprises”,“comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a device, assembly, mechanism, system, method that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such system, or assembly, or device. In other words, one or more elements in a system proceeded by“comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or mechanism.

[0043] Embodiments of the disclosure discloses an actuator for a heave compensator. The heave compensator comprises the actuator which may be configured with an increased stroke length. The actuator comprises a first cylinder configured with a first actuator piston that is connected to a first actuator piston rod. The first actuator piston may be adapted for reciprocation within the first cylinder. The actuator further comprises a second actuator piston configured within at least one second cylinder wherein the at least one second cylinder may be configured around the first cylinder. The second actuator piston is connected to a second actuator piston rod which may be adapted to displace in a direction opposite to the displacement of the first actuator piston. Such a configuration of tile first actuator piston and the second actuator piston provides an increased stroke length to the actuator. Since, both the first actuator piston and the second actuator piston is configured in individual cylinders i.e. the first cylinder and tile second cylinder and displace independently in opposite directions to achieve increased stroke length. [0044] In an embodiment of the present disclosure, the actuator forms part of the heave compensator with its constructional configuration as mentioned above. The heave compensator may comprise a first accumulator and a second accumulator fluidly connected to the actuator to transmit a fluid and a gas respectively for operation of the actuator. At least one booster unit may be fluidly connected to the first accumulator and the second accumulator for discharging boosted gas into the first accumulator and the second accumulator. Additionally, the heave compensator is actively controlled by a control unit which is configured to determine position of the first actuator piston rod and the second actuator piston rod wherein the at least one sensor generates a signal to the control unit on the position parameters of the first actuator piston rod and the second actuator piston rod. Further, upon displacement of the first actuator piston and tile second actuator piston the fluid from a first fluid chamber transfers to a seventh fluid chamber and the fluid from the second fluid chamber transfers to an eighth fluid chamber respectively. Furthermore, the control unit may regulate supply of gas from a first gas tank and a second gas tank to a first gas chamber of the first accumulator and a second gas chamber of the second accumulator to maintain equilibrium of the actuator. Supply of gas takes place upon displacement of the first accumulator piston and a sixth accumulator piston respectively. The control unit further determines temperature of a surrounding media of the actuator and determines volume of the gas in the first accumulator and the second accumulator. Based on the temperature values and the volume of the gas, the control unit operates the at least one booster unit for supplying boosted gas to the first accumulator and the second accumulator, wherein the at least one booster unit is operated to compensate the volume reduction of the gas, corresponding to temperature of the surrounding media of the actuator.

[0045] In yet another non-limiting embodiment of the present disclosure, the actuator of the heave compensator during operation, may channel a fluid flow from the first fluid chamber to the seventh fluid chamber and may channel the fluid flow from the second fluid chamber to the eighth fluid chamber, upon displacement of the first actuator piston and the second actuator piston in a passive mode. Additionally, in the passive mode, the heave compensator channels the fluid from a third fluid chamber to a fourth fluid chamber and vice versa, upon displacement of the first accumulator piston and may channel the fluid from a fifth fluid chamber to a sixth fluid chamber and vice versa, upon displacement of a sixth accumulator piston. In an active mode, the heave compensator regulates the fluid flow from tile first fluid chamber to the seventh fluid chamber and regulates the fluid flow from the second fluid chamber to the eighth fluid chamber, upon displacement of the first actuator piston and the second actuator piston. Additionally, in the active mode, the heave compensator may regulate the fluid from the third fluid chamber to the fourth fluid chamber and vice versa, upon displacement of the first accumulator piston. Additionally, the heave compensator regulates the fluid from the fifth fluid chamber to the sixth fluid chamber and vice versa, upon displacement of the sixth accumulator piston. Also, in the active mode, transfer of gas may take place from the first gas tank and the second gas tank to the first gas chamber and the second gas chamber which may be regulated.

[0046] The disclosure is described in the following paragraphs with reference to Figures 2 to 12. In the figures, the same element or elements which have same functions are indicated by the same reference signs. One skilled in the art would appreciate that the heave compensator 100 and the method as disclosed in the present disclosure can be used in any vessel 102 or installation unit including, but not limited to, a barge, and offshore installations. Here, a person skilled in the art would recognize that interchanging of fluid chambers and gas chambers in the first accumulator 17 and the second accumulator 18, can be modified to achieve heave compensation. Hence, for the sake of simplicity in explanation of the heave compensator 100, in the exemplary embodiment of the present disclosure, the heave compensator 100 having an increased stroke length coupled to the first accumulator 17 and the second accumulator 18 and installed in a water borne vessel 102 is illustrated in the figures.

[0047] Referring to Figure. 2 which is an exemplary embodiment of the present disclosure illustrating a schematic diagram of a water-borne vessel 102, having a heave compensator 100 for hoisting/lifting and transporting a payload 101. The water- borne vessel 102, herein also referred to as the“vessel 102”, is employed to hoist or lift the payload 101 to and/or from an initial location to a target location. Here, the initial location and the target location may be at least one of a seashore, sea surface, a barge, any other water-borne vessel and the like. In an exemplary embodiment, the target location may be a subsea surface 104. However, in one embodiment, the initial location of the payload 101 may be at least one of the sea shore, barge or any other water-borne vessel and the subsea surface 104.

[0048] Further, the vessel 102 is provisioned with a crane member 103, where the crane member 103 is structurally fixed to the vessel 102. The crane member 103 may further be configured to selectively extend from the vessel 102, for assisting during transportation of the payload 101 to and/or from the vessel 102. Here, a cable 105 is configured to assist the crane member 103 in hoisting/lifting and/or descending the payload 101 to and/or from the initial location to the target location. The cable 105 is coupled to the payload 101 via the heave compensator 100, where the heave compensator 100 is used to hoist or lift he payload 101, regardless of the displacement of the crane member 103 and/or the vessel 102. The cable 105 may be spooled within the vessel 102, to regulate hoisting/lifting and/or descending of the payload 101. [0049] Referring to figure 3 an actuator 10 for the heave compensator 100 at no-stroke condition is disclosed. The actuator 10 forms part of the heave compensator 100 wherein the actuator 10 in the present disclosure has an increased stroke length for aiding in hoisting/lifting of the payload 101. The actuator 10 comprises a first actuator piston 1 1 which is connected to a first actuator piston rod l la and is configured within a first cylinder 12. The first actuator piston 11 is adapted for reciprocation within the first cylinder 12. A second actuator piston 13 is configured within at least one second cylinder 14 where, the at least one second cylinder 14 is configured around tile first cylinder 12. The at least one second cylinder 14 further houses a second actuator piston rod l3a which is adapted for reciprocation within the at least one second cylinder 14. The first actuator piston 11 which is connected to the first actuator piston rod l la displaces in a direction opposite to the displacement of the second actuator piston 13 which is connected to the second actuator piston rod l3a.

[0050] In an embodiment, one end of the first actuator piston rod 1 la is provided with a first hook member 36 for hooking the payload 101. Similarly, one end of the second actuator piston is also provided with a second hook member 37 for hooking with the crane 103 via a cable 105. The first cylinder 12 is compartmentalized into a first fluid chamber V1 which is provided on the first actuator piston rod 1 la side and a first chamber A1 which is provided on the first actuator piston 11 side. The first fluid chamber V1 is provided with a port (not shown in figures) through which fluid enters and discharges due to the displacement of the first actuator piston 11. In an embodiment, tile first chamber Al is a closed chamber with no openings and may be maintained in a state of vacuum in order to negate resistance experienced by the first actuator piston 11 during reciprocation of the first actuator piston 11. Here, a person skilled in the art would appreciate that complete removal of atmospheric air from the first chamber Al may be a laborious process, and hence, a predefined quantity of atmospheric air or any other gaseous element may be maintained.

[0051] The second cylinder 14 is compartmentalized into a second fluid chamber V2 which is provided on the second actuator piston 13 side and a second chamber A2 which is provided on the second actuator piston rod l3a side. The second fluid chamber V2 is provided with the port (not shown in figures) through which the fluid enters and discharges due to the displacement of the second actuator piston 13. In an embodiment, the second chamber A2 is also a closed chamber with no openings and may be maintained in the state of vacuum in order to negate any resistance experienced by the second actuator piston 13 during reciprocation of the second actuator piston 13. Here, a person skilled in the art would appreciate that complete removal of atmospheric air from tile first chamber A2 may be a laborious process, and hence, a predefined quantity of atmospheric air or any other gaseous element may be maintained. [0052] In an embodiment, when the actuator 10 has been loaded with the payload 101 the displacement of the first actuator piston 11 takes place which inherently displaces the second actuator piston 13 due to tile transfer of fluid from the first cylinder 12 and the at least one second cylinder 14. Additionally, the first actuator piston 11 and the second actuator piston 13 displaces opposite to each other, thereby generating a longer stroke or piston displacement length within the first cylinder 12 and the at least one second cylinder 14. In an exemplary embodiment, when the first actuator piston rod 1 la is loaded with the payload 101, the first actuator piston 11 displaces along the entire length of the first cylinder 12. Such displacement of the first actuator piston 11 inherently displaces the second actuator piston 13 in a direction opposite to the displacement of the first actuator piston along the entire length of the at least one second cylinder 14, leading to additional travel of the first actuator piston 11 and the second actuator piston 13 thereby resulting in increased stroke length of the actuator 10. [0053] In an embodiment, the second actuator piston 13 may be a ring-shaped piston.

Similarly, the second actuator piston rod 13a may also be a ring-shaped rod and is connected to a connector ring 15 with the second hook member 37 such that, the forces acting on the second actuator piston 13 are imparted at a central location at the second hook member 37. Moreover, the connector ring 15 aids in imparting simultaneous displacement of the second actuator piston 13. Additionally, during operation of the heave compensator 100 at subsea, water may enter a cavity [not shown in figures] below the connector ring 15. This reduces an adverse water pressure effect acting on the heave compensator 100 at subsea. In an embodiment, the second actuator piston rod 13a is configured with a fluid passage 41 to allow passage of fluid around the second actuator piston rod 13a.

[0054] Referring to figure 3, the heave compensator 100 further comprises a first accumulator 17 and a second accumulator 18 fluidly connected to the first cylinder 12 and the at least one second cylinder 14 of the actuator 10 respectively. The first accumulator 17 is compartmentalized in to four compartments. [0055] A first accumulator piston 20 is provided such that, the first accumulator piston 20 is adapted to reciprocate within the first accumulator 17 and divides the first accumulator 17 into a first fluid compartment 26, a second fluid compartment 27, a first gas chamber Gl and a seventh fluid chamber V7. In an embodiment, the first accumulator 17 may be configured as a four chamber accumulator as described above.

[0056] In an embodiment, the first fluid compartment 26 and the first gas chamber Gl are provided on one side of the first accumulator piston 20 while the second fluid compartment 27 and the seventh fluid chamber V7 are provided on other side of the first accumulator piston 20. The first accumulator 17 further comprises, a second accumulator piston 21 and a third accumulator piston 22. The second accumulator piston 21 is connected to the first accumulator piston 20 via a second accumulator piston rod 2 la. [0057] In an embodiment, the second accumulator piston 21 is configured within the first fluid compartment 26 and the third accumulator piston 22 is connected to the first accumulator piston 20 via a third accumulator piston rod 22a.

[0058] In an embodiment, the third accumulator piston 22 is configured within the second fluid compartment 27. The second accumulator piston 21 and the third accumulator piston 22 are adapted to reciprocate within the first fluid compartment 26 and the second fluid compartment 27 respectively. The first fluid compartment 26 further comprises a third fluid chamber V3 configured on the second compensator piston 21 side and the second fluid compartment 27 comprises a fourth fluid chamber V4 configured on the third accumulator piston 22 side. In an embodiment, displacement of the first accumulator piston 20 within the first accumulator 17 in either direction, inherently displaces the second accumulator piston 21 and the third accumulator piston 22. [0059] Similarly, the second accumulator 18 is also compartmentalized in to four compartments. A sixth accumulator piston 25 is provided such that the sixth accumulator piston 25 is adapted to reciprocate within the second accumulator 18 and divides the second compensator 18 into a third fluid compartment 28, a fourth fluid compartment 29, a second gas compartment G2 and an eighth fluid chamber V8. In an embodiment, the second accumulator 18 may be a four chamber accumulator as described above.

[0060] In an embodiment, the third fluid compartment 28 and the eighth fluid chamber V8 are provided on one side of the sixth accumulator piston 25 with the fourth fluid compartment 29 and the second gas compartment G2 on other side of the sixth accumulator piston 25. The second accumulator 18 further comprises a fourth accumulator piston 23 and a fifth accumulator piston 24. The sixth accumulator piston 25 is connected to the fourth accumulator piston 23 via a fourth accumulator piston rod 23 a. In an embodiment, the fourth accumulator piston 23 is configured within the third fluid compartment 28. The fifth accumulator piston 24 is connected to the sixth accumulator piston 25 via a fifth accumulator piston rod 24a. In an embodiment, the fifth accumulator piston 24 is configured within the third fluid compartment 28. The fourth accumulator piston 23 and the fifth accumulator piston 24 are adapted to reciprocate within the third fluid compartment 28 and the fourth fluid compartment 29 respectively. The third fluid compartment 28 further comprises a fifth fluid chamber V5 configured on the fourth accumulator piston 23 side. The fourth fluid compartment 29 comprises a sixth fluid chamber V6 configured on the fifth accumulator piston 24 side. In an embodimen t, di splacement of the sixth accumulator piston 25 within the second accumulator 18 in either direction, inherently displaces the fourth accumulator piston 23 and the fifth accumulator piston 24.

[0061] In an embodiment, the first cylinder 12 of the actuator 10 is fluidly connected to the seventh fluid chamber V7 of the first accumulator 17 forming a closed fluid circuit. Similarly, the at least one second cylinder 14 of the actuator 10 is fluidly connected to the eighth fluid chamber V8 of the second accumulator 18, also forming the closed fluid circuit. [0062] The first gas compartment Gl of the first accumulator 17 is fluidly connected to a first gas tank 38 forming a closed gas circuit. Similarly, the second gas compartment G2 of tile second accumulator 18 is fluidly connected to a second gas tank 39, also forming the closed gas circuit. [0063] Further, the third fluid chamber V3 of the first accumulator 17 is fluidly connected to the fourth fluid chamber V4 and the fifth fluid chamber V5 of the second accumulator 18 is fluidly connected to the sixth fluid chamber V6, thereby forming the closed fluid circuits respectively. In an embodiment, the fluid connection between the third fluid chamber V3 to the fourth fluid chamber V4 and the fifth fluid chamber V5 to the sixth fluid chamber V6 is via one or more prime movers

33.

[0064] In an embodiment, the heave compensator 100 is configured to operate in a passive mode and an active mode. In the passive mode, the fluid flow from tile third fluid chamber V3 to the fourth fluid chamber V4 and vice versa, and the fluid flow from the fifth fluid chamber V5 to the sixth fluid chamber V6 and vice versa, is in the form of free flowing fluid [i.e. fluid flow is not regulated].

[0065] In an embodiment, the heave compensator in the active mode, the fluid flow from the third fluid chamber V3 to the fourth fluid chamber V4 and vice versa, and the fluid flow from the fifth fluid chamber V5 to the sixth fluid chamber V6 and vice versa, is in the form of regulated flowing fluid [i.e. fluid flow is regulated].

[0066] In an embodiment, the first gas tank 38 and the second gas tank 39 are fluidly connected to at least one booster unit 19 via the one or more prime movers 33. The gas present within the first gas tank 38 and the second gas tank 39 may be boosted by tile at least one booster imit 19 and transferred to the first gas chamber Gl and the second gas chamber G2 via the one or more prime movers 33 in order to aid hoisting or lifting and to maintain equilibrium position of the payload 101.

[0067] In an embodiment, the first gas tank 38 and the second gas tank 39 are fluidly connected with a first buffer tank Bl and a second buffer tank B2 respectively, via one or more valve hub 34. The first buffer tank Bl and the second buffer tank B2, supply gas to the first gas tank 38 and the second gas tank 39 respectively when pressure within the first gas tank 38 or the second gas tank 39 has reduced below a predetermined pressure. Additionally, the transfer of gas occurs when there is a position deviation of the actuator 10 between a target equilibrium position and an actual equilibrium position. In an embodiment, the first buffer tank Bl and the second buffer tank B2 store gas in order to readily supply to the first gas tank 38 and the second gas tank 39. In an embodiment, the gas stored in the first buffer tank Bl and the second buffer tank B2 may be supplied to any gas volume via the at least one booster unit 19 or directly to the first gas tank 38, file second gas tank 39, the first gas chamber Gl and the second gas chamber G2. In an embodiment, based on a pressure gradient existing within the gas volumes, the gas stored in the first buffer tank Bl and file second buffer tank B2 are operated to achieve target equilibrium position of the actuator 10. [0068] In an embodiment, the first buffer tank Bl and the second buffer tank B2 is fluidly connected to the one or more valve hub 34. The one or more valve hub 34 is further linked to the control unit 30 that controls directing and re-directing of the gas from the first buffer tank Bl and the second buffer tank B2. In an embodiment, the heave compensator 100 may be configured with one or more buffer tanks in order to main tain target equi librium position of the actuator 10 based on the requirement.

[0069] In an embodiment, the gas from the first buffer tank Bl and the second buffer tank

B2 may be directed to the at least one booster unit 19 via the one or more valve hub 34 for providing boosted gas to the first gas chamber Gl and the second gas chamber G2 or to any other gas volumes.

[0070] In an embodiment, the one or more valve hub 34 comprises of at least one valve block, a dual common channel, at least one gas valve, at least one Minimess checkpoint, a pilot valve and the like. In a further embodiment, the one or more valve hub 34 comprises a gas filling port for filling gas from an external source. [0071] In an embodiment, transfer of fluid from the third fluid chamber V3 to the fourth fluid chamber V4 and vice versa,, and transfer of fluid from the fifth fluid chamber V5 to the sixth fluid chamber V6 and vice versa, occurs via one or more prime movers 33. The one or more prime movers 33 regulate transfer of fluid from one fluid chamber to another fluid chamber based on the heave motion of the vessel 102, wherein the heave motion is calculated by the determination of the position parameters of the first actuator piston rod l la and the second actuator piston rod l3a in the active mode. Additionally, during fluid transfer from the third fluid chamber V3 to the fourth fluid chamber V4, and transfer of fluid from the fifth fluid chamber V5 to the sixth fluid chamber V6 the one or more prime movers 33 may regulate the flow of fluid based on the pressure gradient in order to maintain the actuator 10 at the target equilibrium position in the active mode.

[0072] In an embodiment, the one or more prime movers 33 are further linked to the control unit 30 wherein the control unit 30 controls directing and re-directing of the fluid transfer from the third fluid chamber V3 to the fourth fluid chamber V4, and transfer of fluid from the fifth fluid chamber V5 to the sixth fluid chamber V6. In an embodiment, the flow of fluid in the active mode is regulated by the one or more prime movers 33 and the flow of fluid in the passive mode is not regulated or in a state of free flow of fluid through a first adjustable valve 31 and a second adjustable valve 32.

[0073] In an embodiment, when the first actuator piston 11 is displaced within the first cylinder 12, the fluid present in the first fluid chamber VI is transferred to the seventh fluid chamber V7. As the fluid from the first fluid chamber VI transfers to the seventh fluid chamber V7, volume of fluid present in the seventh fluid chamber V7 increases, thereby displacing the first accumulator piston 20. Similarly, when the first actuator piston 11 displaces in an opposite direction, the fluid that has been transferred from the first fluid chamber VI to the seventh fluid chamber V7 returns back to the first fluid chamber VI. As the first accumulator piston 20 displaces, fluid present in the third fluid chamber V3 is pushed out into the fourth fluid chamber V4 via the one or more prime movers 33. Additionally, some volume of the gas present in the first gas chamber Gl is transferred to the first gas tank 38. Simultaneously, due to the displacement of the first actuator piston 11, the second actuator piston 13 displaces within the at least one second cylinder 14 of the actuator 10. The fluid present in the second fluid chamber V2 is transferred to the eighth fluid chamber V8. Similarly, when the second actuator piston 13 displaces in an opposite direction, the fluid that has been transferred from the second fluid chamber V2 to the eighth fluid chamber V8 returns back to the second fluid chamber V2. As the fluid from the second fluid chamber V2 is transferred to the eighth fluid chamber V8, volume of fluid present in the eighth fluid chamber V8 increases thereby displacing the sixth accumulator piston 25 of the second accumulator 18. As tile sixth accumulator piston 25 displaces, fluid present in the sixth fluid chamber V6 is pushed out into tile fifth fluid chamber V5 via the one or more prime movers 33. Additionally, some volume of the gas present in the second gas chamber G2 is transferred to the second gas tank 39. [0074] Displacement of the first actuator piston 11 imparts displacement to the second actuator piston 13. This displacement of the first actuator piston 11 and the second actuator piston 13 occurs in a direction opposite to each other. Due to the inclusion of the first actuator piston 11 within the first cylinder 12 of the actuator 10, displacement of the first actuator piston 11 occurs within the entire length of the first cylinder 12. Also, the second actuator piston 13 is configured within the second cylinder 14 which also di splaces within the entire length of the second cylinder 14. This configuration of the first actuator piston 1 1 and the second actuator pi ston 13 within the first cylinder 12 and the second cylinder 14 of the actuator 10 leads to increased stroke l ength of the actuator 10.

[0075] In an embodiment, either of the first actuator piston 11 or the second actuator piston 13 may be locked by blocking of fluid flow from the actuator 10 to the accumulators 17, 18. As an example, the fluid flow from tile second fluid chamber V2 to tiie eight fluid chamber V8 may be closed by a first adjustable valve 31 and fluid flow from the first fluid chamber VI to the seventh fluid chamber V7 may be open to allow fluid flow. This configuration, renders only the first actuator piston 1 1 to reciprocate along the entire length of the first cyl inder 12. Fluid flow from the third fluid chamber V3 to the fourth fluid chamber V4 may be regulated in the active mode and fluid flow from the third fluid chamber V3 to the fourth fluid chamber V4 may not be regulated in the passive mode. [0076] Referring to figure 3, which is an exemplary embodiments, wherein the first actuator piston 11 is almost at a top portion of the first cylinder 12, the second actuator piston 13 is almost at the top portion of the second cylinder 14. Here, the position of the first actuator piston 11 and the second actuator piston may be considered at no load condition or when a load applied is smaller than pretension of the actuator 10. Similarly, referring to figure 4, when the actuator 10 is loaded by tile payload 101 and in operation, the first actuator piston 11 is at a mid-portion of the first cylinder 12, and the second actuator piston 13 is also at the mid portion of the at least one second cylinder 14 rendering a mid-stroke condition of the actuator 10. Referring to figure 5, the first actuator piston 11 is at a bottom portion of the first cylinder 12 and the second actuator piston 13 is also at the bottom portion of the at least one second cylinder 14 rendering a full-stroke position of the actuator 10. In an embodiment, distance of length between the first hook member 36 and the second hook member 37 at no-load condition is L [referring to Figure 3], In another exemplary embodiment, the distance of length between the first hook member 36 and the second hook member 37 at the mid-stroke condition is L’ [referring to Figure 4], In yet another exemplary embodiment, the distance of length between the first hook member 36 and the second hook member 37 at full-stoke condition is L” [referring to Figure 5], [0077] Due to the displacement of the first actuator piston 11 and the second actuator piston 13 within the first cylinder 12 and the at least one second cylinder 14, increased stroke length of the actuator 10 is achieved. This allows additional displacement with respect to the actuator 10 for handling payload 101 without having to utilize long stoke cylinders. [0078] In an embodiment, the actuator 10, in-turn the heave compensator 100, is configured to selectively operate in tile passive mode and the active mode. Here, for operating the actuator 10 in the passive mode, transfer of gas from the first gas tank 38 and the second gas tank 39 to the first accumulator 17 and the second accumulator 18 occurs via the one or more prime movers 33 in both the active mode and the passive mode. However, regulation of transfer of gas takes place in order to maintain the target equilibrium position of the actuator 10.

[0079] In the passive mode, gas flow between the first gas tank 38 to the first gas chamber

Gl and gas flow between the second gas tank 39 to the second gas chamber G2 is unregulated or resembles a free flow motion. In an embodiment, as tile payload 101 is lowered towards splash zone [i.e. location where the payload 101 meets the skim of the water surface and the payload 101 is subjected to splashing from the waves generated on the skim of the water surface], the flow of gas from the first gas chamber Gl to the first gas tank 38 is stopped. Also, the flow of fluid from the first fluid chamber VI to the seventh fluid chamber V7 and the flow of fluid from the second fluid chamber V2 to the eighth fluid chamber V8 is unregulated or resembles the free flow motion. Additionally, no regulation is applied in controlling fluid flow from the third fluid chamber V3 to the fourth fluid chamber V4 and fluid flow from the fifth fluid chamber V5 to the sixth fluid chamber V6.

[0080] As an example, for operating the actuator 10 in the passive mode, the actuator 10 is loaded by the crane 103 to hoist or lift the payload 101, the first actuator piston rod 11 a may be subjected to a downward displacement due to weight of the payload 101. The downward displacement of the first actuator piston rod l la in-tum displaces the first actuation piston 1 1 thereby, increasing the pressure within the first fluid chamber VI. As the first fluid chamber VI is fluidly connected to the seventh fluid chamber V7, varying pressure in either or both of the third fluid chamber V3 or the fourth fluid chamber V4, results in fluid exchange, in order to compensate a differential pressure developed therebetween. In an embodiment, the fluid flow from the first fluid chamber VI to the seventh fluid chamber V7 occurs via a first adjustable valve 31. In an embodiment, the first adjustable valve 31 comprises a plurality of valve members for operational control of the first actuator piston rod 11 a. As an example, during operation of the actuator 10, the first actuator piston rod 1 la is unlocked to displace by operating a first adjustable valve member [not shown in figures]. The first adjustable valve member maybe configured to allow limited amount of fluid flow to pass through, to displace the first actuator piston rod 1 la by a small margin. As tire payload 101, reaches the splash zone, a second adjustable valve member [not shown in figures] may be operated to allow flow of fluid to control landing of the payload 101 on the skim of the water surface. During retraction of the first actuator piston rod l la, a third adjustable valve member [not shown in figures] maybe operated which reduces the speed of retraction of the first actuator piston rod l la. Lastly, when the payload 101, is lowered into the subsea or when the heave compensator is in the active mode, a fourth adjustable valve member [not shown in figures] maybe operated to allow fluid flow. In the passive mode, no regulation is applied to the first adjustable valve 31 in controlling the fluid flow from the first fluid chamber VI to the seventh fluid chamber V7.

[0081] Similarly as illustrated in the previous paragraph, due to the downward displacement of the first actuator piston 11, upward displacement of the second actuator piston rod 13a occurs in-tum displacing the second actuator piston 13. This increases the fluid pressure within the second fluid chamber V2. The second fluid chamber V2 is fluidly connected to the eighth fluid chamber V8 via a second adjustable valve 32 to control the fluid flow. In an embodiment and similar to that of the first adjustable valve 31 , the second adjustable valve 32 comprises a plurality of valve members for operational control of the second actuator piston rod l3a. As an example, during operation of the actuator 10, the second actuator piston rod l3a is unlocked to displace by operating a first adjustable valve member [not shown in figures]. The first adjustable valve member maybe configured to allow limited amount of fluid flow to pass through, to displace the first actuator piston rod l3a by a small margin. As tire payload 101, reaches the splash zone, a second adjustable valve member [not shown in figures] may be operated to allow flow of fluid to control landing of the payload 101 on the skim of the water surface. During retraction of the first actuator piston rod l3a, a third adjustable valve member [not shown in figures] maybe operated which reduces the speed of retraction of the first actuator piston rod 13 a. Lastly, when the payload 101, is lowered into the subsea or when the heave compensator is in the active mode, a fourth adjustable valve member [not shown in figures] maybe operated to allow fluid flow. Additionally, varying pressure in either or both of the fifth fluid chamber V5 or the sixth fluid chamber V6, results in fluid exchange, in order to compensate the differential pressure developed therebetween. This differential pressure between the first fluid chamber VI and the second fluid chamber V2 may be controlled in order to maintain target equilibrium position of the actuator 10.

[0082] In an embodiment, when a temperature drop arises between the actuator 10 and its surroundings, the volume of gas in any of the gas volumes reduces drastically. In order to control the differential gas volume gradient within the actuator 10, gas, preferably boosted gas, is selectively supplied from the first buffer tank Bl and the second buffer tank B2 to the first gas chamber Gl and the second gas chamber G2 via the at least one booster unit 19. In an embodiment, based on the pressure gradient existing within the gas volumes, the gas stored in the first buffer tank Bl and the second buffer tank B2 are operated to achieve target equilibrium position of the actuator 10. Simultaneously, transfer of fluid from the third fluid chamber V3 to the fourth fluid chamber V4 and transfer of fluid from the fi fth fluid chamber V5 to the sixth fluid chamber V6 may be regulated. This allows maintenance of the target equilibrium position of the actuator 10 and aids in hoisting or lifting of the payload 101 even in severe weather conditions.

[0083] In an embodiment, the at least one booster unit 19 receives gas from the first gas tank 38, the second gas tank 39, for boosting pressure of the gas. Boosting of pressure of the gas depends on the following. First, to ensure target equilibrium position of the actuator 10 is maintained when the payload 101 moves from air to water [i.e. in the splash zone]. Second, water pressure acting on the actuator 10 rods [i.e. first actuator piston rod 1 l a and the second actuator piston rod l3a] as the payload 101 moves to the depths at subsea. Lastly, in relation to the drop in temperature of the surrounding media of the actuator 10 [i.e. when the payload 101 moves from air to the seabed. [0084] During operation of the actuator 10 in the active mode, the actuator 10 is initially loaded with the payload 101, and the payload 101 is required to be positioned on a buoyant surface such as, but not limited to, the barge, the surface of the sea, any another vessel at sea or tile subsea surface 104, and the like. Here, on positioning of tile payload 101 on the buoyant surface, the first actuator piston rod l la is initially displaced downwardly due to weight of the payload 101 and is subject to a buoyant upward thrust. Also, as the payload 101 is crossing the splash zone the heave compensator 100 is switched to the passive mode. The gas in tile first gas chamber Gl and tile second gas chamber G2 is adjusted in order to match the weight of the payload 101.

[0085] In an embodiment, during displacement and/or positioning of the payload 101 in the subsea [i.e. from air to seabed], due to temperature variation, the volume of gas may volumetrically compress the gas in the first gas chamber Gl and the second gas chamber G2. The compression of the gas in the first gas chamber Gl may then lead to volumetric expansion of the compressible fluid in the third fluid chamber V3 or the fourth fluid chamber V4 and in the seventh fluid chamber V7. Similarly, the compression of the gas in the second gas chamber G2 may then lead to volumetric expansion of the compressible fluid in the fourth fluid chamber V4 or the sixth fluid chamber V6 and in the eighth fluid chamber V8. The disruption of the pressure may allow the actuator 10 to displace from the equilibrium position and deviate the payload 101 from the aligned position. Also, the gas from the first gas tank 38 and the second gas tank 39 loses its volumetric compression, at the sub- zero temperatures. At this moment, the first buffer tank Bl and the second buffer tank B2 may not have requisite pressure to initiate flow of the gas to the first gas chamber Gl and the second gas chamber G2. Hence, during displacement at the subsea or the subsea surface 104, the gas from the first gas tank 38 and the second gas tank 39 are channeled to the at least one booster unit 19. As an example, during operation of the heave compensator 100 at subsea, the drop in temperature of the gas is in the range of about 1° C to about 4° C. This drop in temperature causes drop in volume in all gas volumes within the heave compensator 100. This drop in volume is compensated by supplying boosted gas from the at least one booster unit 19 as described above.

[0086] In an embodiment, the at least one gas booster unit 19 may be provisioned with a double-acting cylinder, which may house a double-headed piston, to enhance the efficiency and speed of boosting the gas.

[0087] In an embodiment, the first actuator piston rod 1 la and the crane member 103, may be coupled with one or more sensors 16. The one or more sensors 16 may be including, but not limited to, a position sensor, a dynamic positioning sensor, a motion reference unit, a proximity sensor, a pressure sensor, an orifice, and the like to determine position of the first actuator piston rod 1 la.

[0088] Here, the first actuator piston rod 1 la and the second actuator piston rod l3a may be coupled with a position sensor such that, displacement of the first actuator piston rod 1 la and the second actuator piston rod l3a during the operation of the heave compensator 100 is detected.

[0089] In an embodiment, changing of operation of the heave compensator 100 from the active mode to the passive mode may be carried out by a user. The user may control operation of the heave compensator 100 via a remote control or via a remote operated vehicle (ROV) which may be deployed at subsea. Alternatively, an acoustic control activation via depth triggering may be used to switch from active mode to passive mode. In an embodiment, the acoustic control can be carried out at any depth, remotely from the vessel 102 or alternatively from the ROV. [0090] In a further embodiment, the crane member 103 and the payload 101 may be coupled with the dynamic positioning sensor and a motion reference unit (MRU) such that, relative movement of either the crane member 103 or the payload 101 may be indicated to tile heave compensator 100. For lifts, spooling information from the crane member 103 to the heave compensator 100 is transferred via acoustic signals or radio signals to the control imit 30. [0091] Further, the one or more sensors 16 may be interfaced with the control unit 30 such that, the control unit 30 may receive indications as input signals from each of the one or more sensors 16. The control unit 30 may then generate operational signals to actively operate components such as, but not limited to, the one or more prime movers 33, the at least one booster unit 19, one or more valve hub 34 and the like. Here, based on the input signals from the one or more sensors 16, the control unit 30 may initially determine position of the first actuator piston rod l la and the second actuator piston rod 13 a, from the one or more sensors 16. Additionally, at subsea, the control unit 30 upon determining temperature of the surrounding media of the actuator 10 may supply boosted gas to the gas volumes to compensate for the loss in gas volume due to drop in temperature. This ensures an effective and efficient operation the heave compensator 100 in both passive mode and active mode. Also, upon receiving input signals from the one or more sensors 16 and the motion reference unit (MRU) coupled to the payload 101 or the crane 103, the control unit 30 may selectively regulate supply of the fluid and gas to the first compensator 17 and the second compensator 18, thereby controlling the actuator

10

[0092] Additionally, during hoisting or lifting, if the pressure of the gas to perform the hoist of the payload 101 is less, then the control unit 30 operates the at least one booster unit 19. This operation of the at least one booster unit 19, by the control unit 30, assists the heave compensator 100 to descend the payload 101 to the subsea surface 104 without turbulence or heave. Moreover, the control unit 30 may also be configured to regulate rate of spool of tile cable 105 and transmit control signals to the heave compensator 100 for a faster response in order to achieve faster and efficient target equilibrium position of the actuator 10. [0093] In an exemplary embodiment, the first buffer tank Bl and the second buffer tank B2 are connected to tile at least one booster unit 19. The first buffer tank Bl and the second buffer tank B2 stores gas, more particularly stores nitrogen gas to readily supply to any gas volume via the at least one booster unit 19 or directly to the first gas tank 38, the second gas tank 39, the first gas chamber G1 and the second gas chamber G2.

[0094] Referring to figures 6, 7 and 8, the heave compensator 100 with the actuator 10 is disclosed. As an exemplary embodiment, the first cylinder 12 and the second cylinder 14 of the actuator are separated. The first cylinder 12 comprises of the first actuator piston 11 connected to the first actuator piston rod 1 la. The first actuator piston 11 on the application of payload 101, displaces within the first cylinder 12. Similarly, the at least one second cylinder 14 is provided around the first cylinder 12, wherein the second actuator piston 13 is connected to the second actuator piston rod l3a and is adapted to displace within the second cylinder. In an embodiment, the second actuator piston rod l3a of the second actuator piston 13 is connected together with the connector ring 15 with the second hook member 37 such that, the forces acting on the second actuator piston 13 are imparted at a central location at the second hook member 37. Moreover, the connector ring aids in imparting simultaneous displacement of the second actuator piston 13 within the at least one second cylinder 14.

[0095] Referring to figure 9, the heave compensator 100 with the actuator 10 as disclosed in the figures 3, at no-stroke condition is depicted. In an embodiment, the first accumulator 17 and the second accumulator 18 are fluidically connected to the actuator 10 similar to the configurations explained in reference to figures 3, 4 and 5. The first accumulator piston 20 provided in the first accumulator 17 divides the first accumulator into the first gas chamber Gl and the seventh fluid chamber V7. In an embodiment, the second accumulator piston 21 is connected to the second accumulator piston rod 2la which is fixed to the internal region of the first accumulator 17. The second accumulator piston 21 is configured within the first fluid compartment 26, wherein the first fluid compartment 26 is fixed to the first accumulator piston 20 on one side. The first fluid compartment 26 further comprises a third fluid chamber V3 configured on the second compensator piston 21 side. In an embodiment, the third accumulator piston 22 is connected to the third accumulator piston rod 22a which is fixed to the internal region of the first accumulator 17. The third accumulator piston 22 is configured within the second fluid compartment 27 wherein the second fluid compartment 27 is fixed to the first accumulator piston 20 on other side. The second fluid compartment 27 further comprises a fourth fluid chamber V4 configured on the third compensator piston 22a side. In an embodiment, the second accumulator piston rod 21 a and tile third accumulator piston rod 22a are configured to be hollow to allow fluid flow. The second accumulator piston rod 2la and the third accumulator piston rod 22a comprises a hollow fluid flow region to allow passage of fluid. As an example, fluid flow from the third fluid chamber V3 to the fourth fluid chamber V4 and vice-versa, occurs through the hollow fluid flow region provided in the second accumulator piston rod 2la and the third accumulator piston rod 22a. In an embodiment, the hollow fluid flow region may be configured with an inner tube 40 to assist fluid flow.

[0096] In an embodiment, displacement of the first accumulator piston 20 within the first accumulator 17 in either direction, inherently displaces the first fluid compartment 26 and the second fluid compartment 27 around the second accumulator piston 21 and the third accumulator piston 22 respectively.

[0097] Similarly, in the second accumulator 18, the sixth accumulator piston 25 divides the second accumulator 18 into the second gas chamber G2 and the eighth fluid chamber V8. In an embodiment, the fourth accumulator piston 23 is connected to the fourth accumulator piston rod 23a which is fixed to the internal region of the second accumulator 18. The fourth accumulator piston 23 is configured within the third fluid compartment 28 wherein, the third fluid compartment 28 is fixed to the sixth accumulator piston 25 on one side. The third fluid compartment 28 further comprises a fifth fluid chamber V5 configured on the fourth compensator piston 23 side. In an embodiment, the fifth accumulator piston 24 is connected to the fifth accumulator piston rod 24a which is fixed to the internal region of the second accumulator 18. The fifth accumulator piston 24 is configured within the fourth fluid compartment 29, wherein the fourth fluid compartment 29 is fixed to the sixth accumulator piston 25 on other side. The fourth fluid compartment 29 further comprises a sixth fluid chamber V6 configured on the fifth compensator piston 24 side. In an embodiment, the fourth accumulator piston rod 23 a and the fifth accumulator piston rod 24a are configured to be hollow to allow fluid flow. The fourth accumulator piston rod 23a and the fifth accumulator piston rod 24a comprises hollow fluid flow region to allow passage of fluid. As an example, fluid flow from the fifth fluid chamber V5 to the sixth fluid chamber V6 and vice versa, occurs through the hollow fluid flow region provided in the fourth accumulator piston rod 23 a and the fifth accumulator piston rod 24a. In an embodiment, the hollow fluid flow region may be configured with the inner tube 40 to assist fluid flow. [0098] In an embodiment, displacement of the second accumulator piston 25 within the first accumulator 18 in either direction, inherently displaces the third fluid compartment 27 and the fourth fluid compartment 28 around the third accumulator piston 23 and the fourth accumulator piston 24 respectively. [0099] Referring to Figure 10, the first actuator piston 11 and the second actuator piston

13 are at a middle portion of the first cylinder 12 and the at least one second cylinder 14. This position of the first actuator piston 11 and the second actuator piston 13 renders a mid-stroke position of the actuator 10. Similarly, referring to figure 11, the first actuator piston 11 and the second actuator piston 13 are at the bottom portion of the first cylinder 12 and the second cylinder 14. This position of the first actuator piston 11 and the second actuator piston 13 renders a full-stroke position of the actuator 10.

[0100] Referring to figure 12 the heave compensator 100 with the actuator 10 as disclosed in the figures 6, at no-stroke condition is depicted. In an embodiment, the first accumulator 17 and the second accumulator 18 are fluidically connected to the actuator 10 with similar configurations explained in reference to figures 9, 10 and 11. As an exemplary embodiment, the first cylinder 12 and the at least one second cylinder 14 of the actuator 10 is separated. The first cylinder 12 comprises of the first actuator piston 11 connected to tile first actuator piston rod 11 a. The first actuator piston 11 on the application of payload 101, displaces within tile first cylinder 12. Similarly, the at least one second cylinder 14 is provided around the first cylinder 12, wherein the second actuator piston 13 is connected to the second actuator piston rod l3a and is adapted to displace within the at least one second cylinder. In an embodiment, the second actuator piston rod l3a of the second actuator piston 13 is connected together with the connector ring 15 with the second hook member 37 such that, the forces acting on the second actuator piston 13 are imparted at a central location at the second hook member 37. Moreover, the connector ring aids in imparting simultaneous displacement of the second actuator piston 13 within the at least one second cylinder 14. [0101] Referring to Figure 13, the first actuator piston 11 and the second actuator piston

13 are at the middle portion of the first cylinder 12 and the at least one second cylinder 14. This position of the first actuator piston 11 and the second actuator piston 13 renders a mid-stroke position of the actuator 10. Similarly, referring to figure 14, the first actuator piston 11 and the second actuator piston 13 are at the bottom portion of the first cylinder 12 and the at least one second cylinder 14. This position of the first actuator piston 1 1 and the second actuator piston 13 renders the full -stroke position of the actuator 10.

[0102] In one embodiment, the control unit 30, the one or more prime movers 33, the one or more valve hub 34, the one or more sensors 16, the at least one booster imit 19, and the crane member 103 may be coupled with a battery unit [not shown in figures], for operation. The battery unit may be at least one of a Li-ion battery, a bundle of super capacitors, a lead-acid battery, an alternator, a power source from the vessel 102 and the like. [0103] In one embodiment, the one or more valve hub 34 may include one or more valves, where each valve of the one or more valves may be identical or of different configuration. Each valve in the one or more valve hub 34 may be connected between the first gas tank 38, the second gas tank 39, the first accumulator 17, the second accumulator 18, the first buffer tank B 1 and the second buffer tank B2 which may be at least one of a bi-directional valve. Further, each of the valves connected to the at least one booster unit 19 may be at least one of a 2/3 valve or a 3/2 valve and the like.

[0104] In an embodiment, the control unit 30 is interfaced to a user interface 35 in order to control operation of tile heave compensator 100 by the user. The user interface 35 comprises of, but not limited to, remote operated vehicle controls, a display imit to display vital parameters of the heave compensator 100, plurality of switches for operation of the heave compensator 100. [0105] In one embodiment, the fluid used in the heave compensator 100 may be a hydraulic fluid including, but not limited to, water, paraffin oil, glycol, SAE oils, and the like.

[0106] In one embodiment, the gas used in the heave compensator 100 may be including, but not limited to, atmospheric air, nitrogen gas, inert gas, and the like.

[0107] In one embodiment, the one or more prime movers 33 includes an electric motor, a hydraulic motor, a water pump, an accelerometer, a motor controller, a booster block, pilot valves, an active heave compensator (AHC) block and the like. [0108] In one embodiment, the actuator 10, the first accumulator 17, the second accumulator 18 and the at least one booster unit 19 may be provisioned with a plurality of seals [not shown in figures]. The plurality of seals may include one or more grooves, which may be configured to house a sealing ring. This configuration of the plurality of seals may be used to maintain the pressure within the actuator 10, the first accumulator 17, the second accumulator 18 and the at least one booster unit 19. [0109] In one embodiment, the control unit 30 may be a centralized control unit 30 for the vessel 102 or may be a dedicated control unit 30 to the heave compensator system associated with the centralized control unit 30 of the vessel 102. The control unit 30 may also be associated with other control units such as a navigation control unit, a gyroscopic control unit, a crane control unit module and the like. The control unit 30 may include specialized processing units such as integrated system (bus) controllers, memory management control units, floating point units, graphics processing units, digital signal processing units, etc. The processing unit may include a microprocessor, such as AMD Athlon, Duron or Opteron, ARM’s application, embedded or secure processors, IBM PowerPC, Intel’s Core, Itanium, Xeon, Celeron or other line of processors, and the like. The control unit 30 may be implemented using mainframe, distributed processor, multi-core, parallel, grid, or other architectures. Some embodiments may utilize embedded technologies like application-specific integrated circuits (ASICs), digital signal processors (DSPs), Field Programmable Gate Arrays (FPGAs), microcontroller, and the like.

EQUIVALENTS

[0110] With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. [0111] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as“open” terms (e.g., the term“including” should be interpreted as“including but not limited to,” the term“having” should be interpreted as“having at least,” the term“includes” should be interpreted as“includes but is not limited to,” etc.), lt will be further imderstood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases“at least one” and“one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles“a” or“an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes tile introductory phrases“one or more” or“at least one” and indefinite articles such as“a” or“an” (e.g.,“a” and/or“an” should typically be interpreted to mean“at least one” or“one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of“two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to“at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g.,“a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to“at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g.,“a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase“A or B” will be understood to include the possibilities of“A” or“B” or“A and B.” [01 12] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group. [0113] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims

WE CLAIM:

1. An actuator 10 for a heave compensator 100 comprising:

a first actuator piston 11 connected to a first actuator piston rod 1 la configured within a first cylinder 12, wherein tile first actuator piston 11 is adapted for reciprocation within the first cylinder 12; a second actuator piston 13 configured within at least one second cylinder 14, wherein tile at least one second cylinder 14 is configured around the first cylinder 12 and the second actuator piston 13 is adapted for reciprocation within the at least one second cylinder 14; and a second actuator piston rod l3a connected to the second actuator piston 13, wherein the second actuator piston 13 is adapted to displace in a direction opposite to the displacement of the first actuator piston 1 1 to achieve increased stroke length of the actuator 10.

2. The actuator 10 as claimed in claim 1, wherein the first cylinder 12 is compartmentalized to a first chamber Al on tile first actuator piston 11 side and a first fluid chamber VI on the first actuator rod 1 la side.

3. The actuator 10 as claimed in claim 1, wherein the second cylinder 14 is compartmentalized into a second chamber A2 on the second actuator piston 13 side and a second fluid chamber V2 on the second actuator rod l3a side.

4. The actuator 10 as claimed in claim 1, comprising a connector ring 15 connected to the second actuator piston rod l3a is adapted to displace with the second actuator piston 13.

5. The actuator 10 as claimed in claim 1 comprising one or more sensors 16 provided on each of the first actuator piston rod 1 la and the second actuator piston rod l3a, wherein the one or more sensors 16 determine position of the first actuator piston rod 1 la and the second actuator piston rod l3a and provides position parameters to a control unit 30.

6. A heave compensator 100 comprising:

an actuator 10 comprising: a first actuator piston 1 1 connected to a first actuator piston rod 1 la configured within a first cylinder 12, wherein the first actuator piston 11 is adapted for reciprocation within the first cylinder 12; a second actuator piston 13 configured within at least one second cylinder 14, wherein the at least one second cylinder 14 is configured around the first cylinder 12 and the second actuator piston 13 is adapted for reciprocation within the at least one second cylinder 14; and a second actuator piston rod 13a connected to the second actuator piston 13, wherein the second actuator piston 13 is adapted to displace in a direction opposite to the displacement of the first actuator piston 11 to achi eve increased stroke length of the actuator 10; a first accumulator 17 and a second accumulator 18 fluidly connected to the actuator 10 to transmit a fluid and a gas for operation of the actuator 10; at least one booster unit 19 fluidly connected to the first accumulator 17 and the second accumulator 18 for discharging boosted gas into the first accumulator 17 and the second accumulator 18.

7. The heave compensator 100 as claimed in claim 6, wherein the first accumulator 17 comprising a first accumulator piston 20, a second accumulator piston 21 and a third accumulator piston 22 adapted for reciprocation within the first accumulator 17 upon displ acement of the first actuator piston 11.

8. The heave compensator 100 as claimed in claim 6, wherein the second accumulator 18 comprising a fourth accumulator piston 23, a fifth accumulator piston 24 and a sixth accumulator piston 25 adapted for reciprocation within the second accumulator 18 upon displacement of the second actuator piston 13.

9. The heave compensator 100 as claimed in claim 6, wherein the second accumulator piston 21 is connected to a second accumulator piston rod 21 a and adapted for reciprocation within a first fluid compartment 26.

10. The heave compensator 100 as claimed in claim 6, wherein the third accumulator piston 22 is connected to a third accumulator piston rod 22a and adapted for reciprocation within a second fluid compartment 27.

11. The heave compensator 100 as claimed in claim 6, wherein the first accumulator piston 20 is connected to the second accumulator piston rod 21 a on one side and is connected to the third accumulator piston rod 22a on other side.

12. The heave compensator 100 as claimed in claim 6, wherein the fourth accumulator piston 23 is connected to a fourth accumulator piston rod 23 a and adapted for reciprocation within a third fluid compartment 28.

13. The heave compensator 100 as claimed in claim 6, wherein the fifth accumulator piston 24 is connected to a fifth accumulator piston rod 24a and adapted for reciprocation within a fourth fluid compartment 29.

14. The heave compensator 100 as claimed in claim 6, wherein the sixth accumulator piston 25 is connected to the fourth accumulator piston rod 23 a on one side and is connected to the fifth accumulator pi ston rod 24a on other side.

15. The heave compensator 100 as claimed in claims 1 and 6 comprising a control unit 30 configured to:

determine position of the first actuator piston rod 1 la and the second actuator piston rod l3a wherein the one or more sensors 16 is configured on the first actuator piston rod 1 la and the second actuator piston rod 13a generates a position parameter signal to the control unit 30;

selectively transfer the fluid from a first fluid chamber VI to a seventh fluid chamber V7 and selectively transfer the fluid from the second fluid chamber V2 to an eighth fluid chamber V8 upon displacement of the first actuator piston 11 and the second actuator piston 13 respectively;

supplying of a gas from a first gas tank Gl and a second gas tank G2 to the first accumulator 17 and the second accumulator 18 upon displacement of the first accumulator piston 20 and a sixth accumulator piston 25 respectively;

determine temperature of a surrounding media of the actuator 10 and determine volume of gas in the first accumulator 17, the second accumulator 18; and

operate at least one booster unit 19 for supplying boosted gas to the first accumulator 17 and the second accumulator 18, wherein the at least one booster unit 19 is operated to compensate the volume of the gas.

16. A Method of operating a heave compensator 100 comprising:

channeling a fluid flow from a first fluid chamber VI to a seventh fluid chamber V7 and channeling the fluid flow from a second fluid chamber V2 to an eighth fluid chamber V8, upon displacement of the first actuator piston 11 and the second actuator piston 13 in a passive mode;

channeling the fluid in-between a third fluid chamber V3 to a fourth fluid chamber V4 and vice versa by adjusting fluid pressure upon displacement of the second accumulator piston 21, channeling the fluid from a sixth fluid chamber V6 to a fifth fluid chamber V5 and vice versa, upon displacement of the fifth accumulator piston 24 respectively in the passive mode;

regulating the fluid flow from the first fluid chamber VI to the seventh fluid chamber V7 and regulating the fluid flow from the second fluid chamber V2 to the eigh th fluid chamber V8, upon displacement of the first actuator piston 1 1 and the second actuator piston 13 in an active mode;

regulating the fluid from the third fluid chamber V3 to the fourth fluid chamber V4 and vice versa upon displacement of the second accumulator piston 21, regulating the fluid from the sixth fluid chamber V6 to the fifth fluid chamber V5 and vice versa, upon displacement of the sixth accumulator piston 25 respectively in the active mode.

17. The method as claimed in claim 16, wherein determining, by a control unit 30, a position of the first actuator piston rod 1 la and the second actuator piston rod l3a and adjusting the fluid and gas pressure in the actuator 10, wherein the control unit 30 operates the actuator 10 between the passive mode and the active mode, based on data received from the one or more sensors 16.