GB2537096A

GB2537096A - Control system for detecting position of an umbilical cable or wire rope attached to a load

Info

Publication number: GB2537096A
Application number: GB1504145.2A
Authority: GB
Inventors: Lavelle Paul; Scott Mackocher James
Original assignee: ENNSUB Ltd
Current assignee: ENNSUB Ltd
Priority date: 2015-03-11
Filing date: 2015-03-11
Publication date: 2016-10-12
Also published as: GB201504145D0

Abstract

A control system for an umbilical cable 104 or wire rope attached to a load is disclosed, in which the umbilical cable or wire rope 104 is routed around a sheave wheel 105 and through a snubber assembly 107 suspended from a deployment system 101. The control system comprises at least one sensor 903 mounted on the snubber assembly configured and arranged to output a position signal indicative of the position of said umbilical cable or wire 104 in relation to said sensor; a controller 901 configured to output a control signal in response to the position signal from the at least one sensor; and a system 902 configured and arranged to effect movement of the snubber assembly in response to the control signal. The at least one sensor may comprise one or more of a mechanical, ultrasonic, infrared, magnetometer or a hall effect sensor.

Description

Control System for Detecting Position of an Umbilical Cable or Wire Rope Attached to a Load

CROSS REFERENCE TO RELATED APPLICATIONS

This application represents the first application for a patent directed towards the invention and the subject matter.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a control system for regulating the position of umbilical cable or wire rope routed around a sheave wheel and through a snubber assembly suspended from a deployment system, with respect to the snubber assembly.

2. Description of the Related Art

An umbilical cable or wire rope attached to a load and routed around * ** * * * *** * a sheave wheel may be hanging at an angle away from the vertical line. In ** ** * * 15 the prior art, it is known to visually observe that such an umbilical cable or * * * wire rope is hanging at an angle away from the vertical and consequently *** *** * may be rubbing on the snubber assembly or a component of the snubber * * assembly such as the umbilical cable docking box (also known as latch * * * *** * ** * assembly). In existing systems, there is a requirement to subsequently * * * ** manually operate one or more pistons, which may be hydraulic or electric, to move the snubber assembly. Moving the snubber assembly alters the angle of the sheave wheel which allows the umbilical cable or wire rope to return to hanging vertically. In this vertical position, the umbilical cable or wire rope no longer rubs on the snubber assembly or an associated component such as the latch assembly.

This known methodology clearly has an inherent disadvantage in that the umbilical cable or wire rope may already be rubbing on the snubber assembly or an associated component such as the latch assembly before this potential erosion of the umbilical cable or wire rope is observed. Physical damage to the umbilical cable or wire rope is dangerous because damage to the electrical cables inside may impair the communicative functions of the umbilical cable or wire rope and also because the load-bearing capacity of the umbilical cable or wire rope may be reduced.

In contrast to this known methodology, the present invention advantageously provides apparatus which allows for a continuous, active and dynamic re-positioning of the snubber assembly to protect the umbilical cable or wire rope from physical damage.

** BRIEF SUMMARY OF THE INVENTION

* * . 4*** * 15 According to an aspect of the present invention, there is provided a control system for an umbilical cable or wire rope attached to a load, in which the umbilical cable or wire rope is routed around a sheave wheel and through a snubber assembly suspended from a deployment system, the control system comprising: at least one sensor mounted on the snubber assembly configured and arranged to output a position signal indicative of the position of said umbilical cable or wire in relation to said sensor; a controller configured to output a control signal in response to the position signal from said at least one sensor; and a system configured and arranged to effect movement of said snubber assembly in response to the control signal. * * *

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BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a standard hydraulic A-frame for use on board a vessel; Figure 2 illustrates a sheave wheel positioned in a snubber assembly; Figure 3 shows a side view of a hydraulic A-frame and sheave wheel with umbilical cable hanging vertically; Figure 4 shows an underside view of a snubber assembly; Figure 5 shows a side view of a hydraulic A-frame and sheave wheel with the umbilical cable hanging away from the vertical line; Figure 6 shows a plan view of four hydraulic pistons driving a snubber assembly associated with a standard hydraulic A-frame; Figure 7 shows an illustration of a sensor embodied in the present invention; Figure 8A shows a plan view of an embodiment; Figure 8B shows a perspective view of an embodiment; and Figure 9 illustrates a schematic of the control system embodied in the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Figure 1 Figure 1 depicts a standard hydraulic A-frame 101 which is used for lifting, moving and deploying a range of equipment associated with a vessel.

Standard hydraulic A-frame 101 is a typical deployment system on board a vessel. This equipment may be used to deploy a load such as tether management system (TMS) 102 and/or remotely operated vehicle (ROV) 103. Submersible ROV 103 may be fitted with cameras, lights and manipulating devices to enable underwater investigations to be performed.

Such pieces of equipment are deployed by being lowered into the sea * o* * * * 1.** * * * * Se ** * * * 0 * *** * *** * * * *** * ** * * * * *ti attached to umbilical cable 104. Umbilical cable 104 is typically at least 1,000 metres long and may be up to 10,000 metres long and is a load-bearing steel armoured cable containing electrical conductors and fibre optics to allow power, video and data signals to be transmitted back and forth between the submersible ROV and the vessel. Umbilical cable 104 weighs approximately tonne and provides up to six kilovolt (6kV). Alternatively, a wire rope may be used to deploy a load. The term umbilical cable is used throughout the specification but it is to be appreciated by the skilled person that a wire rope could also be used.

Umbilical cable 104 is spooled via sheave wheel 105 from winch drum 106 and used to lower pieces of equipment such as TMS 102 and ROV 103 into the sea. Umbilical cable 104 is routed around sheave wheel 105.

A further component of hydraulic A-frame 101 is snubber assembly 107. Sheave wheel 105 is fixed into snubber assembly 107. Umbilical cable 104 is routed around sheave wheel 105 and then umbilical cable 104 ideally needs to be deployed vertically through the centre of snubber assembly 107. * ** * *

******* The function of snubber assembly 107 is therefore to dampen the movement * * * of a swinging load and to continue damping the movement of a swinging load ** ** * * * when the load is moving on and off a vessel. -* ***

* 20 In addition, in the illustrated embodiment there are a plurality of * * ** hydraulic pistons 108 which drive snubber assembly 107 in two directions, * *** ** ** * namely from side to side and forwards and backwards. In the illustrated * * * * embodiment, there are two pairs of hydraulic pistons 108 arranged perpendicularly to each other. The first pair drives snubber assembly 107 from side to side whilst the second pair drives snubber assembly 107 forwards and backwards. The arrangement of hydraulic pistons 108 is further shown in Figure 6. Actuation of hydraulic pistons 108 alters the position of snubber assembly 107 which is necessary in order to adjust the position of sheave wheel 105, and consequently, the angle at which umbilical cable 104 hangs down from sheave wheel 105 through centre of snubber assembly 107. In an alternative embodiment, pistons 108 may be, for example, electric pistons.

When TMS 102 and ROV 103 are raised out of the sea, umbilical cable 104 is spooled via sheave wheel 105 onto winch drum 106 and TMS 102 and ROV 103 are docked onto hydraulic A-frame 101 by a latch assembly (also known as a docking box), not here shown. The latch to assembly is, however, described in co-pending British application no. 1418838.7, in the name of the present assignee. The latch assembly represents a safety measure to ensure TMS 102 and ROV 103 are mechanically connected to hydraulic A-frame 101 as they are brought onboard the vessel. * **

* * * *** * * * * * * * * * * . * * * * * * . *** * * * * * * Figure 2 Figure 2 shows sheave wheel 105 fixed into position in snubber assembly 107.

In the illustrated embodiment, snubber assembly 107 is attached to standard hydraulic A-frame 101 at pivot point 201. Standard hydraulic A-frame 101 is a typical deployment system on board a vessel and is used for lifting, moving and deploying a range of equipment associated with a vessel.

Figure 3 Figure 3 shows a side view of a hydraulic A-frame 101 and sheave wheel 105 with umbilical cable 104 hanging directly vertically. A component of hydraulic A-frame 101 is snubber assembly 107, into which sheave wheel * ** 105 is fixed. In the illustrated embodiment, snubber assembly 107 is attached to hydraulic A-frame 101 at fixture 201 which may be known as a pivot point. Umbilical cable 104 runs around sheave wheel 105 and then onto or off a winch drum (not here shown).

* ** 5 In the illustrated embodiment, skirt 301 is attached to snubber *** * assembly 107. Skirt 301 represents the base of snubber assembly 107 and comprises latch assembly (or docking box) 302. In use, docking box 302 serves to grasp the umbilical termination socket (not shown) of umbilical cable 104 and hold it in a fixed position. When docking box 302 is in a resting position, umbilical cable 104 is free to move upwards and downwards between the two fingers of docking box 302.

As standard, four hydraulic pistons (two through dam pistons and two cross dam pistons) drive snubber assembly 107 in two directions, from side to side and forwards and backwards respectively. Only one hydraulic piston 108 is visible in Figure 3. The perpendicular arrangement of the hydraulic pistons is shown in Figure 6. Movement of snubber assembly 107 is necessary to align snubber assembly 107 with umbilical cable 104.

In Figure 3, umbilical cable 104 is hanging directly vertically down from sheave wheel 105. The umbilical cable 104 ideally needs to hang down vertically from sheave wheel 105.

However, there are two main reasons why the umbilical cable 104 may be out of alignment with the snubber assembly 107.

Firstly, snubber assembly 107 may move out of alignment with respect to umbilical cable 104. This may occur due to a mis-alignment between the umbilical cable geometry and snubber assembly pivot-point 201 which causes a tipping of snubber assembly 107. For example, snubber assembly 107 may move out of alignment with respect to umbilical cable 104 ** * * * * * * * * * * * * * *** * ** * * * ** if the vessel is on a rough sea.

Secondly, umbilical cable 104 may move out of alignment with respect to snubber assembly 107. This may happen when umbilical cable 104 drifts due to strong sea currents.

When any of the above events happen, it is necessary to operate the hydraulic pistons 108 to drive snubber assembly 107 to align snubber assembly 107 with the umbilical cable 104. In the prior art, the angle of the umbilical cable needs to be observed visually and the pistons need to be operated manually. ***

* * * *** * * * * * * * * * * * * * * ** * * * * * * * *** * ** * * * * ** Figure 4 A view showing the underside of snubber assembly 107 is shown in Figure 4. Sheave wheel 105 is positioned into snubber assembly 107. Umbilical cable (not herein shown) needs to be deployed vertically through central hole 401 of snubber assembly 107. If umbilical cable is not deployed vertically though snubber assembly 107, umbilical cable may rub on snubber assembly 107 and be damaged.

Figure 5 Figure 5 shows a side view of a hydraulic A-frame 101 and sheave wheel 105 with umbilical cable 104 hanging away from the vertical line. A component of hydraulic A-frame 101 is snubber assembly 107. Sheave wheel 105 is positioned into snubber assembly 107. Umbilical cable 104 runs around sheave wheel 105 and then onto or off a winch drum (not shown). Attached to snubber 107 is skirt 301, which comprises docking box 302. Docking box 302 serves to grasp the umbilical termination socket (not shown) of umbilical cable 104 and hold it in a fixed position.

As standard, four hydraulic pistons (two through dam pistons and two cross darn pistons) drive the snubber assembly in two directions, from side to side and forwards and backwards respectively. Only one hydraulic piston 108 is visible in Figure 5. The perpendicular arrangement of the hydraulic pistons is shown in Figure 6. Movement of snubber assembly 107 is necessary in order to ensure that umbilical cable is deployed vertically through centre of snubber assembly 107.

In Figure 5, umbilical cable 104 is hanging away from the vertical line and this is undesirable because umbilical cable 104 may be rubbing on snubber assembly 107 or a component such as docking box 302. The umbilical cable 104 is a steel-armoured rope comprising electrical cables and must not be damaged. Damage to the umbilical cable 104 is dangerous because damage to the electrical cables inside may impair the communicative functions of the umbilical cable and also because the load-bearing capacity of the umbilical cable may be reduced. * **

* . * *** * * * * ** ** * * * * * ** * * ** * * * *** * ** * * ..

Figure 6 As standard, four hydraulic pistons, two through dam pistons 601 and two cross dam pistons 602, drive the snubber 107 in two directions, from side to side and forwards and backwards respectively. A plan view of the perpendicular arrangement of the two pairs of hydraulic pistons 601 and 602 is shown in Figure 6. Snubber assembly 107 is also seen in this plan view with umbilical cable 104 emerging from the sheave wheel beneath snubber assembly 107. Through dam pistons 601 drive snubber assembly 107 from side to side whilst cross dam pistons 602 drive snubber assembly 107 forwards and backwards.

Actuation of hydraulic pistons 601 and 602 drive snubber assembly 107 which alters position of the snubber assembly 107 to ensure that umbilical cable 104 is deployed directly through the centre of snubber assembly 107.

The present invention therefore embodies a control system which regulates the position of snubber assembly 107 by actuating the hydraulic pistons in accordance with the current position of the umbilical cable in relation to snubber assembly 107. Actuation of the hydraulic pistons corrects the position of snubber assembly 107 to ensure that umbilical cable 104 is deployed vertically through centre of snubber assembly 107.

* ** ep * * *** * * * * ** * * * * * * * * * * * * * ** * * * *** * e* * * * * ** Figure 7 Figure 7 shows a side view of a hydraulic A-frame 101 and associated components embodying the apparatus of the present invention.

A component of hydraulic A-frame is snubber assembly 107. In the illustrated embodiment, snubber assembly 107 is attached to hydraulic A-frame 101 at fixture 201. Umbilical cable 104 runs around sheave wheel 105 and then onto or off a winch drum (not shown). In the illustrated embodiment, sensor 701 is a single ultrasonic sensor positioned above docking box 302 on snubber assembly 107 on one side of umbilical cable 104. However, it is to be appreciated that in alternative embodiments, sensor 701 may be positioned beneath docking box 302 or may comprise a number of sensors positioned on snubber assembly 107.

In the illustrated embodiment, sensor 701 continuously detects the position of snubber assembly 107 and its alignment with umbilical cable 104. Movement of snubber assembly 107 is necessary in order to ensure that umbilical cable 104 is deployed vertically through the centre of snubber assembly 107. Thereby, sensor 701 causes a continuous and dynamic re-* ** * * . *** * * * * ** ** * * * * * * ** * * * * * * * *** * ** * * * ** positioning of snubber assembly 107 which ultimately protects umbilical cable 104.

The purpose of the at least one sensor is to detect movement of the umbilical cable with respect to the snubber assembly. If the umbilical cable moves in one direction, this movement is detected by the at least one sensor which then generates a position signal indicative of the position of the umbilical cable with respect to the snubber assembly. The at least one sensor then feeds this position signal back into a controller which is configured to output a control signal in response to the position signal from the at least one sensor. The control signal directs the hydraulic pistons to move the snubber assembly which ensures that the umbilical cable is deployed vertically through the centre of snubber assembly 107.

In the embodied invention, four hydraulic pistons (two through dam pistons and two cross dam pistons) drive snubber assembly 107 in two directions, from side to side and forwards and backwards respectively. Only one hydraulic piston 108 is visible in Figure 7. The perpendicular arrangement of the hydraulic pistons is shown in Figure 6. However, it is to be appreciated by the person skilled in the art that an alternative number of pistons may be deployed, and that as an alternative to hydraulic pistons, electric pistons may be deployed.

Figure 8 Figure 8A shows a plan view of the apparatus in an embodiment of the present invention and Figure 8B shows a perspective view of the apparatus in an embodiment of the present invention. In the illustrated embodiment, the apparatus comprises a disc-shaped sensor housing 801 with a central circular aperture 802. However, alternatively shaped sensor * ** * * * ** * . * * * * a* * * * * * * * * ** * * * *** * ** * * * * * ..

housings with alternatively shaped apertures are within the scope of the present invention. The sensor housing may, for example, be square shaped and the aperture may, for example, be oval shaped.

The sensor housing 801 is fabricated in two separate halves to enable it to be positioned around the umbilical cable. Once the two halves of the sensor apparatus have been positioned around the umbilical cable, they are clipped or attached together to form a single unit. Thus, the umbilical cable lies within the central aperture 802. Any suitable means known in the art may be used to attach the two halves together. The sensor housing 801, which may be a disc-shaped housing, may be fabricated from steel, nylon or phosphobronze, for example.

As shown in Figure 8, a plurality of sensors 803 are attached to the disc-shaped sensor housing 801 so that their sensing elements point inwards towards the aperture 802. The sensors 803 may therefore be positioned on the upper side of the sensor housing 801 or within the central aperture 802.

In the illustrated embodiment, sensors 803 must not present any mechanical resistance with the umbilical cable and their functioning must not rely on a mechanical interaction between the apparatus and umbilical cable, thus being described as non-mechanical sensors. Examples of suitable sensors include ultrasonic sensors, infrared sensors, magnetometers and Hall effect sensors.

However, in an alternative embodiment, sensors 803 may be at least one mechanical sensor. Such at least one mechanical sensor functions by physically contacting the umbilical cable or wire rope. Mechanical sensors are therefore within the scope of the present invention. The at least one mechanical sensor may work by operating an electrical device which signals to a control system to operate the pistons, which themselves may be * ** * * . ** * . * * S. ** * a * * ** * 20 * ** * * * ** * * * * * S* hydraulic or electric. There may be a plurality of mechanical sensors.

An ideal number may be four sensors, and in the embodiment illustrated in Figure 8, there are four electrical sensors 803. However, any number of electrical sensors such as six, eight or ten may be deployed. The actual number is dependent on the range of detection of each individual sensor. Therefore, fewer electrical sensors may be used where the electrical sensors have a wide detection range, whilst more electrical sensors are required where the sensors have a narrower detection range.

In an alternative embodiment, there may be a single sensor attached to to the snubber assembly 107 or a component such as docking box 302.

The purpose of the at least one sensor is to detect movement of the umbilical cable. If the umbilical cable moves in one direction, this movement is detected by the at least one sensor. The at least one sensor, which may be mechanical or non-mechanical, generates a position signal indicative of the position of the umbilical cable with respect to the snubber assembly. The at least one sensor then feeds this position signal back into a controller which is configured to output a control signal in response to the position signal from the sensor. The control signal directs the hydraulic pistons to move the snubber assembly which ensures that the umbilical cable is deployed vertically through the centre of snubber assembly 107.

The embodied control system is thus a closed loop control system which regulates the position of the snubber assembly 107 with respect to the umbilical cable 104 by sensing this relative position and ensuring that the snubber assembly 107 is in alignment with the umbilical cable 104.

Figure 9 The control system embodied in the present invention is illustrated schematically in Figure 9. The present proposal ensures that the umbilical cable will never rub on any steelwork in the snubber assembly or the docking box as it passes downwards from the sheave wheel through the centre of the snubber assembly. Any movement of the snubber assembly is sensed by the embodied apparatus and a movement of the snubber assembly initiated to ensure the umbilical cable is deployed vertically through the centre of the snubber assembly.

The present proposal therefore embodies a control system for an umbilical cable or wire rope 104 attached to a load such as an ROV, in which the umbilical cable is routed around a sheave wheel and through a snubber assembly suspended from an onboard vessel deployment system such as an A-frame. The control system comprises sensor 903 configured to detect how central the umbilical cable is within the snubber assembly. In the illustrated embodiment, sensor 903 is a single ultrasonic sensor attached to snubber assembly 107 beneath docking box 302. The control system further comprises a controller 901 configured to output a control signal in response to the position signal from the sensor. For example, if the umbilical cable moves away from a central position within the snubber assembly such that it is not hanging vertically through the centre of the snubber assembly, this position will be detected by the sensor which will output a position signal indicative of the position of the umbilical cable with respect to the snubber assembly. The controller will then output a control signal to hydraulic control system 902 in response to the position signal from the sensor. This will regulate the movement of the snubber assembly by way of one or both of the two pairs of hydraulic pistons 401 and 402. In alternative embodiments, pistons 401 may be electric pistons. It is to be appreciated by the person skilled in the art that there may be any number of pistons. * **

* * * *** * * * * ** * * * * * * *I** * *** * * * *** * ** * * * In contrast to known systems, in which it may be observed by a person that the umbilical cable is rubbing on the docking box or snubber assembly, thereby necessitating the requirement to manually drive the pistons, the present invention provides an active system in which rubbing is prevented. The present proposal therefore provides a closed loop control system which allows for a continuous, active and dynamic re-positioning of the snubber assembly in order to protect the umbilical cable or wire rope from physical damage. * * * * * *

* * * * * * * * * * * ** * * * * * * is * * * * * * * * * * * 0 * * *

Claims

Claims What we claim is: * * * * * * * * * * * * * 1. A control system for an umbilical cable or wire rope attached to a load, in which the umbilical cable or wire rope is routed around a sheave wheel and through a snubber assembly suspended from a deployment system, the control system comprising: at least one sensor mounted on the snubber assembly configured and arranged to output a position signal indicative of the position of said umbilical cable or wire in relation to said sensor; a controller configured to output a control signal in response to the position signal from said at least one sensor; and a system configured and arranged to effect movement of said snubber assembly in response to the control signal.
2. A control system as claimed in claim 1, wherein said load is a tether management system or remotely operated vehicle. ** ** * * * * **** deployment system is an A-frame. * *
3. A control system as claimed in claim 1, wherein said * * * 20 * * * * * * . *
4. A control system as claimed in claim 3, wherein said A-frame is ** * * * * * * a hydraulic A-frame.
5. A control system as claimed in claim 1, wherein said at least one sensor is a mechanical sensor relying on a physical interaction between said sensor and said umbilical cable or wire rope. * ** * * ** * * * * * * * * * * ** ** * * * * * * * * * * * ** *** * * * * * * * * **
6. A control system as claimed in claim 1, wherein said at least one sensor does not rely on a mechanical interaction between said sensor and said umbilical cable or wire rope.
7. A control system as claimed in claim 6, wherein said at least one sensor is any of an ultrasonic sensor, infrared sensor, magnetometer or Hall effect sensor.
8. A control system as claimed in claim 1, wherein said at least one sensor is mounted on any position of said snubber assembly.
9. A control system as claimed in claim 8, wherein said at least one sensor is fixed onto a docking box on said snubber assembly.
10. A control system as claimed in claim 1, comprising a plurality of sensors.
11. A control system as claimed in claim 1, further comprising a sensor housing for surrounding said umbilical cable or wire rope. 20
12. A control system as claimed in claim 11, wherein said sensor housing comprises a central aperture.
13. A control system as claimed in claim 12, wherein said sensor housing is fabricated in two identical halves.
14. A control system as claimed in claim 11, wherein said sensor housing comprises at least one screw thread to receive said at least one sensor.
15. A control system as claimed in any one of claims 1 to 14, comprising apparatus for detecting position of an umbilical cable or wire rope attached to a load, in which the umbilical cable or wire rope is routed around a sheave wheel and through a snubber assembly suspended from a deployment system, the apparatus comprising: at least one sensor mounted on the snubber assembly configured to output a signal indicative of the position of said umbilical cable or wire rope relative to said snubber assembly.
16. Apparatus substantially as described and shown in Figures 2 to 9. * *** * * ** * * * * * ** ** * * * * * ** * * * * * * * . *** * * * * * * * * **