EP3177521A1

EP3177521A1 - Underwater inspection and monitoring apparatus

Info

Publication number: EP3177521A1
Application number: EP15749854.4A
Authority: EP
Inventors: Mahir Moss MUSTAFA
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-08-05
Filing date: 2015-08-05
Publication date: 2017-06-14
Also published as: GB2524338B; GB201413874D0; WO2016020677A1; GB2524338A

Abstract

The present invention provides an underwater inspection and monitoring apparatus, comprising: at least one sensor (40) configured to function underwater, the at least one sensor being supportable by a diver when in use, wherein each sensor is connected by a transmission line (22) to a remote, out of water, surface positioned processor and controller (30), whereby control signals for the at least one sensor are generated by the controller and signals generated by the at least one sensor are processed by the processor, the signals being passed along the at least one transmission line. This enables the processor and controller to be kept out of water making the sensor(s) easily portable and easy to use thereby reducing the risk of instruments being lost and making the inspection and monitoring process more safe, efficient and cost effective. Further, the values generated by the at least one senor may be displayed on the surface console and to the diver simultaneously and may be stored.

Description

UNDERWATER INSPECTION AND MONITORING APPARATUS

Field of the Invention This invention relates to an inspection and monitoring apparatus, particularly for underwater use.

Background Underwater inspection, monitoring or measurement generally requires specially designed underwater instruments. Such inspection, monitoring and measurement instruments may be used by a diver for obtaining information about underwater objects, such as installations, pipelines, vessels or ship's hulls, or conditions, or for providing information on the physiological status of the diver himself and his environment (e.g. the immediate environment around the diver). The instruments must be robust enough to survive in the underwater environment, yet simple enough for a diver, who may lack technical expertise, to use. Thus, conventional measuring instruments tend to be expensive. The instruments are also bulky and heavy which produces operational problems. It is not practical for a diver to carry all the instruments he may need with him during a underwater inspection, therefore when the diver is submerged and could be carrying out the inspection, time is lost in deploying and recovering inspection instruments. Expensive equipment may be lost or damaged whilst the diver is moving between inspection positions or when substituting one instrument for another.

Existing inspection and monitoring instruments have lanyards attached to them, which are secured to a "D" ring on a diver's harness with a snap-on karabiner. For the diver to use a particular instrument, he may have to unclip that instrument from his harness, which due to the limited vision from his helmet, he cannot see. In doing so, the diver can inadvertently release and lose another instrument. Over a period of time, the diver can also inadvertently release the unsecured instrument and drop it. Instruments are often lost or damaged and this operational problem becomes very expensive.

To date, all the equipment used is based on the principle of having a whole instrument (i.e. the display, control and processing parts as well as the sensor or probe) underwater. However, apart from being expensive, the instruments are also very bulky as the electronic control and processing elements have to be submerged as well as any sensor used to take measurements together with a separate display for each individual instrument, and the problems associated with the existing inspection and monitoring instruments still exist. The bulkiness of the current instruments presents a safety hazard for the diver, as they restrict the diver's movements and present a snagging hazard.

A video camera is often used during inspection and monitoring as part of a diver's equipment. The diver's video camera is mounted on top of the diver's diving helmet in a fixed position and cannot be altered by either the diver or the topside inspection controller (also referred to as an Inspection Coordinator or an Inspection Engineer) who controls the inspection dive. If the diver has discovered a defect, for example deep pitting corrosion, and wishes to show it to the topside inspection controller, and if the camera is out of alignment he will have to move his head up or down, left or right or to one side so as to bring the camera into alignment. This results in only one party being able to view the defect at any one time making it difficult for the diver to comment on the subject under examination. Parallax error (the difference between the position of the video camera and the diver's view) further contributes to this problem. Underwater video surveys are very expensive to perform. However, these video recordings enable the components, which have been recorded, to be examined by other competent parties such as the certifying authority or the installation operator's asset integrity engineers at a later date. It therefore follows that the video recording should be produced to a high quality to enable any fine defects present (which the diver may or may not have reported) to be later observed. Although High Definition video has been available for some years, it is not readily used in underwater surveys. This is because of the limitations of data transfer in the copper cables provided for within existing diver's umbilical.

A further consideration is that if a diving company is contracted to provide say a capability for taking wall thickness measurements, then, given that most diving operations are for a 24 hour period, they need to purchase a minimum of two wall thickness meters to take the measurements they have been contracted for; so that is one meter on charge whilst the other is in use. In practice, they will have a minimum of three meters, the third meter being a spare in case one of the other two are either damaged or lost. This triples the cost of the equipment required to perform a specific inspection function. With existing systems during an inspection dive, a diving supervisor monitoring a diver's depth and reserve bottle contents must periodically interrupt the inspection being carried out. This is in order to obtain the divers depth and reserve bottle contents pressure for safety reasons. This is achieved by the diver stopping whatever he is doing, locating his reserve bottle contents pressure gauge and reporting to the diving supervisor the reading on the gauge, typically a value of around 200 bar. It should be noted that the present arrangement only provides for measuring the pressure of the breathing gas in the reserve bottle (Air, Nitrox or Heliox).

The supervisor obtains the divers depth by opening a valve and allowing air/gas to travel down a "Pneumo" hose, which forms part of the divers umbilical terminating at the level of the divers chest. The diver reports to the supervisor when bubbles appear out of the end of the hose, and the pressure required to displace the water within the hose is calibrated to show the divers depth on a mechanical gauge located in dive control. The diver cannot see this reading and relies on the diving supervisor to read his depth correctly and accurately work out how much no decompression time he has remaining for his dive or the required decompression schedule, which the diving supervisor calculates manually from printed decompression tables. This manual process of calculating the divers depth and decompression schedule can and has on occasions lead to mistake being made resulting in either the diver suffering from decompression sickness or if the error is caught in time, the diver having to undergo an emergency decompression schedule which can last for several hours.

The processes of obtaining the diver's depth and reserve bottle contents pressure take about a minute but are carried out regularly (as often as every 30 minutes). Even if these measurements were carried out once every hour, and performed in 30 seconds, this would amount to approximately 12 minutes over a 24 hour period of diving and over a typical 30 day inspection campaign it amount to 360 minutes or 6 hours. Presently, saturation diving can cost in excess of £10,000 per hour so it could equate to £60,000 of unproductive dive time.

These processes not only interrupt the inspection but also are a likely time when the diver can inadvertently drop an instrument due to the distraction. This system also has severe limitations since the vital measurements are only applicable at one instant. The diver could quite easily have gone deeper before or after taking the measurement and without the diving supervisor noticing this. The function of the divers reserve bottle (carried on the divers back) is, as the name implies, a backup air/gas supply sufficient to save the diver should his main supply, through an umbilical to the surface, cease. It is activated by the diver operating a valve on the side of his helmet. There have been numerous cases where the diver has accidentally operated this valve, without realising, and has depleted the emergency supply. Once again, the measurement of the remaining backup air/gas supply is only valid for that moment, which is a reason why a supervisor checks on the amount remaining in the reserve bottle so frequently.

The diver may not be required to carry out inspection tasks using measurement instruments, for example when involved in a dive dedicated to performing a construction task, but will still require inspection and monitoring instruments to monitor data related to the diver's welfare. However, there may be an unplanned requirement to take a measurement. In such a case, with exiting arrangements the relevant inspection instrument will need to be sent down to the diver, which is time consuming.

It is known to use an underwater display device such as a video screen, which displays data obtained by a diver so that the diver can see the results and make further measurements according to his interpretation of those results rather than relying on instructions from a topside operator.

Summary of Invention

In accordance with an aspect of the present invention, there is provided an underwater inspection and monitoring apparatus, comprising: at least one sensor configured to function underwater, the at least one sensor being supportable by a diver when in use, wherein each sensor is connected by a transmission line to a remote, surface positioned processor and controller, whereby control signals for the at least one sensor are generated by the controller and signals generated by the at least one sensor are processed by the processor, the signals being passed along the at least one transmission line. Each sensor may have its own transmission line, or each sensor may share a transmission line with one or more other sensors thereby reducing the number of transmission lines required. By sensor, we mean active and passive sensors including probes.

The present invention provides inspection and monitoring apparatus, which overcomes the disadvantages of conventional types of monitoring apparatus by having the processor and controller at a remote site and at least one simple slave sensor underwater. Such a sensor is easily portable and if lost, is less expensive to replace than a complete instrument. Unlike conventional measuring instruments, there is no requirement for recharging equipment since each sensor is powered from the surface. No electronics are required underwater to control a sensor or to process the signals produced into usable data values which saves weight and bulk (and thereby efficiency) and significantly reduces the chance of loss or damage, thereby reducing cost.

Conventional instruments have waterproofing around the control and processing unit in order to protect them when underwater. This waterproofing can fail, which causes the instrument to flood, resulting in the instrument being unusable. Using the inspection and monitoring apparatus removes this risk, as the control and processing unit no longer requires waterproofing. The at least one sensor is not limited to being a measuring sensor for inspection, but may alternatively, or additionally, include a monitoring sensor to monitor data related to the welfare and/or the physiological condition of the diver.

The uniqueness of this inspection and monitoring apparatus is to leave only the sensors with the diver and to house and power their associated control and processing electronic components in a topside console. This not only significantly reduces the cost of providing these diver safety monitoring and inspection measurement functions but it also reduces the weight and bulk of the equipment the diver has to carry. The sensors are only a small fraction of the size and weight of existing equipment so the diver can easily carry all of these sensors with him all the time and thereby save time and cost by eliminating the need to deploy this equipment from the surface to the diver. Signal degradation and limited information transmission capacity (which occurs in metallic conductors) may be overcome by using optical fibre together with a digitiser (for converting any analogue signals), an electrical to optical converter and a multiplexer, which provides the link between underwater sensors and the topside unit. The rationale for this inspection and monitoring apparatus is not to reinvent existing instrumentation but to integrate and package them in a more cost effective and efficient way. Dive Data Recording System's, Wall Thickness, Cathodic Potential meters and other such instruments already exist and have been extensively tried and tested over numerous years, this system will essentially make them more efficient and cheaper to use and will improve on the quality of relaying the measurements obtained by the diver from these instruments to the surface. This integrated approach also provides for readily adding and providing the diver with more inspection and monitoring sensors as operationally required and as new technology emerges. Essentially, the apparatus enables the sensor's processor and controller to be kept out of water and provides for one common display making the sensor(s) easily portable and easy to use thereby reducing the risk of instruments being lost and making the inspection and monitoring process more safe, efficient and cost effective. Further, the values generated by the at least one senor may be displayed on the surface console and to the diver simultaneously and may be stored.

For short distances copper cable is acceptable, for signal carrying transmission lines however, this quickly becomes expensive if any great distance is to be covered, and the weight of copper becomes too heavy for the diver to carry out inspections unhampered as the number of sensors increases. Another disadvantage of copper is signal loss where signals are transmitted along a pair of long copper cables. So, signal degradation makes the use of copper cables over long distances difficult, and the information transmission capacity is limited. Therefore, the signal carrying at least one transmission line may comprise at least one optical fibre. This reduces weight and provides an improved quality signal over long distances than with copper cable. Further, signals sent through optical fibre can be multiplexed allowing multiple signals to be sent simultaneously through a single optical fibre. Multiplexing is possible using copper cables, but is difficult due to skin effect. Due to greater clarity of signal, it is easier to send and receive digitised signals using optical fibre and unlike copper cables, optical fibre is not prone to electromagnetic interferences.

The at least one transmission line may include a power cable. This allows an operator on the surface to power, control and adjust a sensor directly.

There may be a plurality of transmission lines, each one of which carries signals two and from an individual sensor. However typically, there is a single common transmission line along which signals generated by the controller and signals generated by each sensor are able to pass (i.e. from the one sensor, or from each of the plurality of sensors). This may be enabled by multiple signals being multiplexed and transmitted along a single optical fibre or copper cable. Alternatively, when there are at least two sensors, each sensor of the at least two sensors being connected to a respective transmission line , and wherein the transmission lines (i.e. at least two transmission lines) are grouped together into an umbilical, which acts as a single common transmission line.

For the apparatus, each end of each optical fibre may be connected to an electrical to optical signal converter to convert between electrical and optical signals. There may be one converter at each end of the umbilical for every sensor, but preferably, a common converter is provided at each end of the single common transmission line configured to convert the signal for each respective optical fibre.

Typically, at least one converter is mountable on a diver in use.

The at least one converter may be mounted on a harness to be worn by the diver in use.

A video camera may be attached to a mounting, which mounting is mountable on a diver in use. The mounting may be motorised such that the video camera is moveable (e.g. pan and tilt) relative to the diver when in use. In other words, the video camera may be movably mounted on a motorised mounting. Typically, the position of the mounting is variable by remote control. The video camera may also have a built in focus near and far functionality. The zoom and focus of the camera may also be adjustable.

For inspection purposes, the inspection and monitoring apparatus may comprise all of the commonly used underwater inspection instruments, and typically include at least one of a cathodic potential (CP) sensor (which provides for obtaining CP values either by means of the sensor making direct contact with the structure or by placing it near to the structure known as CP proximity readings (both measured in mV)), and also provide for CP current density measurements (measured in mA), a wall thickness sensor (measured in mm), an alternating current field measurement sensor (which, by means of interpreting a displayed graphical waveform, indicates the absence or presence of a defect/crack), an ambient light sensor (measured in lux), a ultra violet (UV) sensor (measured in mW/cm²), a magnetic flux density sensor (measured in Tesla), a digital ruler and/or a laser range finder ruler (measured in mm, cm or m). Further instruments may include at least one of an ultrasonic flaw detector sensor), an eddy current sensor (both of which, by means of interpreting a displayed graphical waveform, indicate the absence or presence of a defect/crack, an FMD (Flooded Member Detection) sensor (which indicates whether a tubular submerged member is flooded, partly flooded or void of water), a 3D (three-dimensional) laser scanner (which scans an object and produces an accurate digital three-dimensional model of the object), an imaging sonar (which produces continuous graphical images of objects within its field of view even in zero visibility), and/or other form of sensor or inspection instrument in order to readily and comprehensively provide status, integrity and metrology information about an underwater structure being analysed. Both an ultrasonic flaw detector sensor and an eddy current sensor are crack and defect detecting sensors. One or more of the sensors named above may be connected to an auxiliary socket located in a pouch in the diver's harness which in turn is connected to the signal converter for transmitting signals so that they can be included when needed instead of being one of the "standard" sensors that are normally carried by the diver.

For safety (and for some of the functions for inspection) purposes, the inspection and monitoring apparatus may include at least one of a water depth and altimeter (i.e. height above the floor of the body of water in which the diver is located e.g. the seabed) sensor (which also provides for timing the duration the diver has been submerged, tidal sensor (measuring the velocity and direction of the water current), hot water temperature sensor, location tracking sensor, gas cylinder level sensor and/or a contents/gas mix sensor to provide diver status information and information on the physiological condition of the diver. The components of the tidal sensor will also provide the diver with a stand-alone compass facility for diver orientation purposes.

Data transferred to the processor and controller may be stored, but alternatively, or additionally, the data transferred may be displayed in real time on a high-resolution monitor, for example a High-Definition (HD) monitor such as an HD television monitor. The high-resolution video feed that is displayed on the high- resolution monitor may only be able to be transmitted through an optical fibre, and not through a copper cable due to the data transfer rate required for such a feed. The optical fibre also may also allow clearer communications with a diver than when using copper cable.

The high-resolution monitor may display data values overlaid on a recorded/live-feed image of an area being measured. The data may also be directly inserted into a digital datasheet being completed that is displayed on a second monitor. For example, the value in millimetres of a wall thickness measurement taken by the diver can be displayed on the surface monitor and entered directly into a digital data sheet without the need to type and thereby preventing errors from occurring. It is also possible to display a map or computer generated simulation/model of the structure that is being inspected, and to superimpose the diver's location on the map/model. This can provide useful information to the people on the surface so that they may direct the diver. This can be important as it is known for a diver to inspect the wrong part of a structure due to the difficulties in correctly identifying a structure or part of a structure and in particular if the visibility is poor.

In use, data produced by at least one of the at least one sensors may be displayable on a head up display in a diving helmet.

In another example, the sensors may be mounted on a remotely operated underwater vehicle (ROV), or may be permanently installed on an object such as an offshore installation or a ship to allow for continuous monitoring. Preferably, the remotely operated underwater vehicle is a Class I, Class II, Class III or Class V remotely operated underwater vehicle. It is beneficial to mount the sensors on one of the identified classes of ROV, as these classes of ROV float/swim in the water instead of operating on the seabed. As such, using the sensors allows additional weight on the ROV to be kept to a minimum whilst expanding the inspection and montoring capabilities of the ROV.

In accordance with another aspect of the present invention, there is provided an underwater inspection and monitoring kit, comprising: at least one sensor configured to function underwater; a garment to be worn by a diver in use, the garment supporting the at least one sensor; a controller adapted to generate control signals for the at least one sensor, and which is located in use at a surface position; a processor adapted to process signals produced by the sensors, and which is located in use at a surface position; and at least one transmission line to connect the controller and processor to the at least one sensor when in use.

In accordance with a further aspect of the present invention, there may be provided a method for conducting underwater sensing, comprising the steps: generating control signals for at least one sensor with a controller; sending the control signals from a surface position to the at least one sensor at an underwater position along at least one transmission line; producing a signal with one of the at least one sensor; sending the produced signal to a processor at a surface position along the at least one transmission line; processing the produced signal with the processor

The method may use the apparatus according to any form described above or the kit according to any form described above. Brief Description of Figures

Examples of inspection and monitoring apparatus in accordance with the present invention will now be described with reference to the accompanying drawings, in which :-

Figure 1 shows part of the inspection and monitoring apparatus of the present invention in use;

Figure 2 shows an example of a remote processor for the inspection and monitoring apparatus of Figure 1 ; and,

Figure 3 shows an example of a connector/digitiser/converter/multiplexer for use with the inspection and monitoring apparatus of Figure 1 .

Detailed Description

In the example shown in Figure 1 , a diver wears a harness 20 in the form of a sleeveless jacket typically made up of nylon fabric material with adjustable straps and numerous pouches 1 -6. The rear of the harness supports an emergency gas cylinder 21 which may be air, nitrox (a mixture of Oxygen and Nitrogen with a higher percentage of Oxygen than air, such as 32% or 36%), trimix, i.e. a Nitrogen, Helium and Oxygen mixture, a He/0₂ mixture (known as Heliox, which contains no Nitrogen), or any other gas mix used for underwater diving.

The harness is capable of holding a number of different sensors, which are for inspection purposes and/or for monitoring the diver's welfare and physiological condition. This enables two functions to be performed, an inspection function and a safety function. The sensors are each electrically connected to a connector box 12, which is a signal converter box for the signals generated by the sensors. At the base of the harness, a D-ring 13 and karabiner support an umbilical 22. The umbilical comprises a power and transmission line and a gas supply line. The umbilical may also consist of a hot water supply to the diver. The gas supply line is connected into the diver's helmet 23 and the transmission line is connected to the signal converter box 12.

Figure 3 shows the signal converter box 12 in more detail. The transmission line 24 enters the signal converter box 12 through a seal. The transmission line is made up of a plurality of optical fibres, each of which is connected to a multiplexer (not shown), which in turn is connected to an electrical to optical signal converter (not shown). This means that when a signal comes through the optical fibre, it arrives in the signal converter box, is demultiplexed (i.e. separated into the constituent signals) and is converted from an optical signal to a digital electrical signal. On another face of the signal converter box 12, a number of sockets 26 are provided to receive electrical signals from the sensors. Alternatively there may be on single socket which connect to multiple sensor leads. Where required, analogue signals from a sensor are converted to digital signals with an analogue-to-digital converter (not shown), also known as a digitiser. The digital signals from the sensors are then able to be converted to optical signals, and are passed on to the multiplexer. As noted above, signals can also be sent to the sensors through the reverse of this process.

Connected into the sockets 26 are insulated copper leads, each of which is terminated with a different type of sensor 40. The leads 41 emerging from the sockets 26 with their associated sensors 40 are usually stored in individual pouches 1 -6 on the front of the harness, or lead directly to a sensor attached to a piece of the diver's kit, such as the harness 20, helmet 23, umbilical 22 and/or gas cylinder 21 .

Additional sockets in the signal converter box 12 are provided for voice communications 28 to and from the diver and High Definition video signals 29 from a helmet mounted camera 10, which has a dual inspection/safety purpose as it allows the inspection object to be observed as well as the conditions of the dive site to be monitored. A microphone is connected via a lead 9 (see Fig. 1 ) from the diver's helmet to the signal converter box 12, and a separate loud speaker (not shown) inside the helmet enables the diver to receive commands from topside operators. The video camera 10 is mounted on the top of the diver's helmet 23 beside a spotlight 1 1 , which is used to illuminate an area so that a picture may be obtained. The camera 10 is mounted to pan and tilt under topside operator control by use of a motor 15. In addition to the sensors 40 that the diver will use, he may be provided with a display 14, typically digital, which will enable the diver to monitor values. This can be a wrist mounted display, e.g. with a velcro strap, a "head up" display 46 in the helmet, or a tablet display on a lead 44, which is storable with its connecting lead 44 in another pouch. The display 14 may be provided with a magnetic base to attach it close to an area being inspected. Data displayed may include readings from one or more of the sensors, such as the inspection and/or safety sensors. Whether optical fibres or copper cables are used and when multiple signals are to be sent through a single fibre or cable, the signal converter box 12 has a digitising and multiplexing capability to digitise any sensors that generate analogue signals and to multiplex signals.

Figure 2 shows the remote processing equipment, which is kept topside (i.e. out of the water). The main processing unit 30 has two monitors 39, 32 and there may be a number of separate monitors (not shown) that are connected to the main processing unit 30. On a support ship, this enables an inspection controller to monitor the progress of the inspection and for a dive supervisor to monitor the physiological condition of the diver, whilst also allowing a representative of the company commissioning a survey to watch its progress on another monitor and for the captain of the ship or bridge officers on the bridge to see that there is a diver down and what he is doing via a monitor. The diving supervisor is able to communicate with the diver via a headset (not shown) and to read details of the diver's status in order to ensure that the diver does not spend too long underwater or get into an unsafe situation. The inspection controller is provided with a microphone 33 and speaker 34 on the processing unit or alternatively a headset (not shown), by which he directs the diver to parts of the underwater structure, which he may wish to look at more closely or obtain further images or readings from. The inspection controller can control movement of the camera 10 and to zoom and focus near or far (i.e. zoom and focus in or out) from topside using a switch system 36. Information may be recorded on a recordable medium, such as a hard disk, solid-state drive, CD, DVD or Blu-ray disk using a recording drive 37 or hard copies of a displayed image output via a colour or black and white video printer 38. Data from the sensors 40 or reference data from the processor memory may be superimposed on the image appearing on a screen 39 so that an instant comparison of actual readings and expected readings can be made. The main processing unit also has buttons 35 for controlling (e.g. activating and deactivating) the various measurement and monitoring sensors. The physical buttons may be replaced with virtual buttons replicated on a (e.g. touch screen) monitor, which may be activated by placing the cursor over the virtual button and clicking a mouse or by means of touch using a touch screen.

When an inspection is to be carried out, examples of inspection instruments stored in these pouches 1 -6 are ambient light sensor; UV sensor and; magnetic flux density probe (used for ensuring the quality of an underwater magnetic particle inspection performed to detect cracks in welds); ACFM probes; wall thickness probe; cathodic potential probe; and, digital ruler and/or laser measure (i.e. a laser rangefinder). Typically, these pouches 1 -6 are secured by velcro lined flaps. As an alternative, the sensors may be connected to the leads 41 from the signal converter box 12 via separate connectors mounted in each pouch so that the only part of the lead, which is movable once the diver has put on his harness 20, is the section 27 between the sensor 40 and its pouch 1 -6. As a further alternative, the sensors may all be held in a single pouch that is attachable to a diver.

As will be readily understood, the sensors are waterproof and able to take measurements underwater. The size of the sensors is kept small through the use of microelectronics in the sensors.

As an example of a process that may be carried out, the topside inspection controller instructs the diver to use a particular sensor e.g. wall thickness and the diver removes that sensor from its pouch. The inspection controller activates that sensor with the controller and instructs the diver to take a reading. Activating the sensor causes control signals generated to be transmitted along the transmission line 24 to activate the sensor. Upon instruction, the diver places the sensor on the structure and a reading is generated e.g. 23.4mm, which is displayed to the inspection controller on the screen 39 and diver simultaneously (as shown in figure 3). As well as displaying the live video feed from the camera 10 to the inspection controller on the screen 39, the live video feed can also be displayed to the diver on his display.

The transmission and display of the sensor reading is achieved as follows: the sensor generates an electrical signal that is routed by cabling within the diver's harness into the signal converter box located in a kidney pouch on the diver's harness. The signal converter box converts electrical signals into optical signals, which are multiplexed. The multiplexed optical signals are then transmitted along an optical fibre within the diver's umbilical to the surface where another converter box (referred to hereafter as a deconverter box). This de-multiplexes the signal received from the optical fibre to separate the signals from the individual sensors and converts the optical signals back into the original electrical signals. These electrical signals are then processed in the topside console and the values displayed on the topside monitors and also sent back along the fibre to the diver's display.

If the sensor should happen to generate analogue signals, then these are first converted into digital signals at the converter box in the diver's harness before being converted into optical signals. The signals from each sensor could be transmitted via separate optical fibres but, as noted, may also be multiplexed and several signals from several different sensors simultaneously transmitted along a single common optical fibre, which is commonly known, and possible by, for example, changing the frequencies of the signals generated by each sensor. Alternatively, the signal could be transmitted via one or more copper cables, and the signal may or may not be multiplexed when transmitted through the copper cable(s).

When the topside inspection controller instructs the diver as to which tasks he requires to be carried out, and can cause control signals generated by the controller to be transmitted along transmission line 24 to activate a sensor. Then the diver extracts the activated sensor 40, carries out a calibration check and begins to take measurements. Numerical values of the measurements are displayed on the screen 39 as they are obtained and also they are displayed to the diver on site. This is enabled by signals generated by the sensor being transmitted along the transmission line 24 from the activated sensor to the processor and, back to the diver's display. There is also a second screen 32 on which further information may be viewed. This is used to display a digital datasheet that is to be completed for the survey. There is a digital overlay that enables the inspection controller to locate a cursor in an appropriate location on the digital datasheet to copy data into an appropriate location on the digital datasheet. There is also the facility to type in additional text and overlay it onto the recorded video picture which may include who is carrying out the inspection, the location of the subject being inspected (e.g. name of the operator, platform, component identification coordinates, elevation), details of the type of inspection (e.g. a magnetic particle inspection), and details of any defects that may be present (e.g. crack, impact damage pitting corrosion)

There will usually be two optical fibres in the transmission line 24 along which sensor related signals are transmitted. One fibre is dedicated to sending signals from the surface to the diver, and the other fibre is dedicated to sending signals from the diver to the surface. The HD video signal produced by the camera is transmitted along a third optical fibre. As such, there are two optical fibres that transmit data from the diver to the surface and one optical fibre that transmits data to the diver from the surface in the diver's umbilical.

Information from the sensors may be entered and overlaid onto a video recording. For example, the location of a defect may be shown on a video feed, and to indicate the existence and nature of a defect, which has been noticed by the diver or inspection controller as the inspection proceeds the data produced by a defect sensor may be displayed on the screen overlaid on the video feed. Hard copies of frames of the video recording (i.e. still images) may also be produced for closer inspection, rather than requiring separate photographic equipment to be taken underwater to be used by the diver. Alternatively, an ordinary camera could be used to photograph the video image displayed topside and the photograph developed in the normal way. It would also be possible for the diver to take stills with a stills camera or using the video camera, which may have the capability of taking stills. Alternatively, it is possible to take screen grabs of the monitor displaying the video. These can then be printed.

Although copper cable is functional, it is preferable to use fibre optic cable. The fibre optic cable is typically housed in a waterproof durable polyethylene sheath and connected between a remote processing terminal and the signal converter box. A typical length for underwater inspection would be 200 metres. Power is supplied by a pair of current carrying conductors provided within the sheath. The main benefits of fibre optic cable are that its high capacity allows more information to be passed at high data rates for the same diameter of cabling. It has low attenuation so there is virtually no signal loss. It is free from electromagnetic interference, and can withstand a smaller radius bend than copper cable of the same diameter. Fibre optics are lighter than conventional copper wiring and less expensive. For example, over a 200 metre length attenuation of a signal in a fibre will be less than 0.5dB, whereas the attenuation for a twisted pair of copper cables is around 20 to 30dB at a frequency of 10MHz. Should a copper cable be used, it is also likely that a power booster would be needed adding weight to the equipment held by the diver and multiplexing the signal would be much more complex due to the difficulties caused by skin effects.

The system of the present invention is particularly appropriate for use in hostile environments, such as offshore oil installations for underwater inspection. Other uses include operating the system on remotely operated underwater vehicles (ROVs) rather than using a diver.

ROVs fall within five classes as defined by The International Marine Contractors Association (IMCA) in their "Code of Practice for The Safe & Efficient Operation of Remotely Operated Vehicles", IMCA R 004 Rev.3 2009.

This defines the classes as follows: Class I - Observation ROVs - These vehicles are small vehicles fitted with camera/lights and sonar only. They are primarily intended for pure observation, although they may be able to handle one additional sensor (such as cathodic protection (CP) equipment), as well as an additional video camera.

Class II - Observation ROVs with Payload Option - These vehicles are fitted with two simultaneously viewable cameras/sonar as standard and are capable of handling several additional sensors. They may also have a basic manipulative capability. They should be able to operate without loss of original function while carrying two additional sensors/manipulators.

Class III - Work-Class Vehicles - These vehicles are large enough to carry additional sensors and/or manipulators. Class III vehicles commonly have a multiplexing capability that allows additional sensors and tools to operate without being 'hard-wired' through the umbilical system. These vehicles are generally larger and more powerful than Classes I and II. Wide capability, depth and power variations are possible.

Class IV - Towed and Bottom-Crawling Vehicles - Towed vehicles are pulled through the water by a surface craft or winch. Some vehicles have limited propulsive power and are capable of limited manoeuvrability. Bottom-crawling vehicles use a wheel or track system to move across the seafloor, although some may be able to 'swim' limited distances. These vehicles are typically large and heavy, and are often designed for one specific task, such as cable burial.

Class V - Prototype or Development Vehicles - Vehicles in this class include those still being developed and those regarded as prototypes. Special- purpose vehicles that do not fit into one of the other classes are also assigned to Class V. This class includes autonomous underwater vehicles (AUVs).

The system of the present invention is primarily able to be used with Class I, Class II, Class III and Class V ROVs as these float in the water and so are able to benefit from only a small amount of additional equipment needing to be mounted to the ROV since it adds little weight to the ROV whilst allowing it to inspect and monitor more. Typically, Class IV ROVs are not used since they usually do not float or swim through water but sit or move around on the seabed.

As well as offshore commercial diving, there are inshore tasks such as underwater inspection of jetties, ship's hulls, slip-ways, dock gates, sea outfalls, bridges, and pipelines, which may be carried out more cost effectively by retaining the processing function topside. It is considered that there will also be defence applications.

To take a measurement using the digital ruler, the diver places the digital ruler on the start position and presses a button on the probe to zero the display. He then moves the probe along the distance to be measured and presses another button to freeze the measurement. The dimensional value is then displayed both topside and underwater.

The laser rangefinder is a hand held instrument, electrically connected to the harness which is able to measure the distance from the instrument (whether held "free" by the diver, of held against part of a structure by the diver), which measures distances by measuring the travel time of a laser pulse as it is emitted from the instrument and reflected back by a surface. Of course, the laser rangefinder will be adapted to work underwater, and so accounting for the speed of light in the water instead of in air.

Other features which may be measured are whether a member has been flooded, depth of crack, ultrasonic flaw detection and sizing, eddy current inspection, alternating current field measurement (ACFM) for detecting defects such as cracks in welds, an FMD sensor and/or ultrasonic scan sensor. The sensors used will be dependent on what the survey is directed to. As such, the required sensors may be plugged in to ports in the signal converter box. There may also be the provision of a helium unscrambler for diver to topside communication for saturation diving.

Since inspection tasks can generally be divided into routine and specialized, a user may choose to carry out his own routine inspections using the system of the present invention and add sensors to carry out specialized inspections or employ specialists who have the required sensors. By transmitting all data directly back to the topside inspection controller, there is no opportunity for human error such as confusion as to the value or the position from which the reading was taken where communications are poor. A diver need not be highly qualified in engineering aspects, but can merely follow the instructions of the inspection controller.

Turning to the safety aspects, in use, the diver wears his harness 20 over a diving suit with communication, camera, and light leads connected to his helmet 23. In terms of the sensors used to perform the diver safety monitoring function, the cylinder is provided with a sensor 8 to indicate the pressure inside the cylinder 21 (representing the remaining content of breathing gas in the cylinder 21 ). There may also be a sensor that analyses the gas mix in the cylinder to monitor constituents of the gas contained in the cylinder 21 . Additionally a gas flow sensor, a gas temperature sensor and an oxygen partial pressure sensor 42 is positioned on the side of the diver's helmet, and a hot water sensor 43 is provided in the harness.

The diver's safety and physiological status is a separate concern to the inspection operations that are capable of being conducted. As such, the sensors that monitor the diver and the local conditions are just as important as the sensors used for the inspection. Other features of diver safety that may be monitored include diver depth, reserve bottle pressure, water current velocity and direction, hot water temperature received by diver, rate of gas flow, temperature of gas to diver, and oxygen partial pressure of mixture received by diver. As noted above, these are monitored by sensors attached to the harness and/or to the diver's gas cylinder, or gas feed block connected to the side of the diver's helmet.

Visual and audible alarms may be activated in response to sensed measurements of diver data passing predetermined thresholds. Hard copy outputs of physiological data and interpretation of the data reduce the risk of operator error resulting in the diver being in a dangerous situation.

For air diving, or for diving where the dive begins from the surface, the diver will be lowered from a platform or ship into the water by means of a diving basket while his umbilical 22 is paid out from the surface as required. A pressure sensor 7 in the diver's harness activates an elapsed dive time counter and provides data for a digital depth reader. This occurs when the diver enters the water as the sensor gets wet and the water applies pressure to it, which activates the sensor.

For saturation diving, the pressure sensor is activated when the diving bell is locked off from the storage system in order to time the bell "lock off" to "lock back on" duration (which should not exceed 8 hours), and is activated a second time when the diver enters the water from the bell getting the sensor wet in order to time the duration of the saturation divers dive (which should not exceed 6 hours). The depth readout is displayed both topside and directly to the diver's digital display 14. When the diver reaches the required depth, the basket or diving bell is stopped and the diver swims to a chosen work-site.

In order to obtain a complete profile of the dive, a pressure and elapsed time sensor may be fitted to the entry lock and main chamber of the decompression chamber/s. These sensors will relay information to the dive control console and provide data relating to the decompression profile the diver is subjected to including the surface interval from where the diver arrives on surface and is then recompressed in the chamber. The means for relaying this data will either be by transmitting the signal through the air, a fibre optic link or an electrical cable.

The dive control console may have a resident program which automatically calculates a decompression schedule for a given dive depth and duration. This same program may also provide data of the dive profile for further analysis and archiving.

As noted above, there may be a sensor or sensors that monitor the quality of the gas being fed to the diver. Any such sensor may be placed on the surface of the gas line that provides the diver with his breathing gas. The function of such a sensor would be to monitor the quality of the gas being fed to the diver and to relay this data to the dive control console. As detailed above, in turn, this would trigger an audible and visual alarm if the breathing gas was contaminated or did not conform to stipulated criteria.

As the inspection and safety aspects of the system are able to operate separately, the remote processing equipment may be split into two units where one unit serves the diving supervisor and the other serves the inspection controller/data recorder.

In this instance, the diving supervisors unit would serve as a "dive control console" and have control of the diver safety monitoring functions of the system, namely: depth and elapsed time, reserve contents pressure, hot water temperature, water current velocity, gas flow/gas temperature and PP0₂ (partial pressure of oxygen).

The other unit would serve as the inspection control console and have control of the inspection functions of the system, namely: light and UV, flux density, wall thickness, cathodic potential, digital ruler and any other specialised inspection instrumentation.

Whether or not the remote processing equipment is split into two units or remains as one unit, there can be a locator connected to the diver that the inspection controller and/or the diving supervisor can view a feed from which can be overlaid on a 3D model of the structure being inspected and the surrounding area.

Both systems would share control over the following functions: communications, video camera, pan and tilt, motor, focus near or far, video light and diver's depth.

The means for relaying this data will either be by transmitting the signal through the air, a fibre optic line or an electrical cable. Instead of using copper cable or optical fibres to transmit data and signals between a diver and a controller and processor on the surface, the data and signals could be transmitted wirelessly.

It should be noted that modifications and improvements may be incorporated without departing from the scope of the invention.

Claims

1 . An underwater inspection and monitoring apparatus, comprising:

at least one sensor configured to function underwater, the at least one sensor being supportable by a diver when in use, wherein

each sensor is connected by a transmission line to a remote, out of water, surface positioned processor and controller, whereby control signals for the at least one sensor are generated by the controller and signals generated by the at least one sensor are processed by the processor, the signals being passed along the at least one transmission line.

2. The underwater inspection and monitoring apparatus according to claim 1 , wherein there is a single common transmission line along which signals generated by the controller and signals generated by each sensor are able to pass.

3. The underwater inspection and monitoring apparatus according to claim 1 , wherein there are at least two sensors, each sensor of the at least two sensors being connected to a respective transmission line, and wherein the transmission lines are grouped together into an umbilical, which acts as a single common transmission line.

4. The underwater inspection and monitoring apparatus according to claim 1 or claim 2 or claim 3, wherein the or each transmission line comprises at least one optical fibre.

5. The underwater inspection and monitoring apparatus according to claim 4, wherein each end of each optical fibre is connected to an electrical to optical signal converter.

6. The underwater inspection and monitoring apparatus according to claim 4 when dependent on claim 2 or claim 3, wherein there is a single common electrical to optical signal converter provided at each end of the single common transmission line configured to convert the signal for each respective optical fibre.

7. The underwater inspection and monitoring apparatus according to claim 5 or claim 6, wherein at least one converter is mountable on a diver in use.

8. The underwater inspection and monitoring apparatus according to claim 7, wherein the at least one converter is mounted on a harness to be worn by a diver in use.

9. The underwater inspection and monitoring apparatus according to any one of the preceding claims, wherein the at least one transmission line includes a power cable.

10. The underwater inspection and monitoring apparatus according to any one of the preceding claims further comprising a video camera attached to a mounting, which mounting is mountable to a diver when in use.

1 1 . The underwater inspection and monitoring apparatus according to claim 10, wherein the mounting is motorised such that the video camera is moveable relative to the diver when in use.

12. The underwater inspection and monitoring apparatus according to any one of the preceding claims, wherein the sensors include at least one of a cathodic potential sensor, a wall thickness sensor, an alternating current field measurement sensor, an ambient light sensor, a ultra violet light sensor, a flux density sensor, a digital ruler, a laser range finder, an ultrasonic flaw detector sensor, an eddy current sensor, a 3D laser scanner, an imaging sonar and/or an FMD sensor.

13. The underwater inspection and monitoring apparatus according to any one of the preceding claims, wherein the sensors include at least one of a water depth and altimeter sensor, tidal sensor, hot water temperature sensor, location tracking sensor and/or reserve gas cylinder level and contents sensor.

14. The underwater inspection and monitoring apparatus according to according to any one of the preceding claims, wherein data transferred to the processor and controller is displayed in real time on a high-resolution monitor.

15. The underwater inspection and monitoring apparatus according to according to any one of the preceding claims, wherein in use data produced by at least one of the at least one sensor is displayable on a head up display in a diving mask.

16. The underwater inspection and monitoring apparatus according to any one of the claims 1 to 14, wherein the at least one sensor is mountable on a remotely operated underwater vehicle.

17. The underwater inspection and monitoring apparatus according to claim 16, wherein the remotely operated underwater vehicle is a Class I, Class II, Class III or Class V remotely operated underwater vehicle.

18. An underwater inspection and monitoring apparatus substantially as described herein, with reference to and as illustrated in the accompanying drawings Figure 1 , Figure 2 and Figure 3.

19. An underwater inspection and monitoring kit, comprising:

at least one sensor configured to function underwater;

a garment to be worn by a diver in use, the garment supporting the at least one sensor;

a controller adapted to generate control signals for the at least one sensor, and which is located in use at an out of water surface position;

a processor adapted to process signals produced by the sensors, and which is located in use at an out of water surface position; and at least one transmission line to connect the controller and processor to the at least one sensor when in use.

20. The underwater inspection and monitoring kit according to claim 19, wherein there is a single common transmission line along which signals generated by the controller and signals generated by each sensor are able to pass.

21 . The underwater inspection and monitoring kit according to claim 19, wherein there are at least two sensors, each sensor of the at least two sensors being connectable to a respective transmission line, and wherein the transmission lines are grouped together in an umbilical, which acts as a single common transmission line.

22. The underwater inspection and monitoring kit according to claim 19, 20 or 21 , wherein the at least one transmission line comprises an optical fibre and each end of the at least one transmission line is connected to an electrical to optical converter when in use.

23. An underwater monitoring kit substantially as described herein, with reference to and as illustrated in the accompanying drawing Figure 1 and Figure 2.

24. A method for conducting underwater sensing using one or more sensors carried by a diver, comprising the steps:

generating control signals for at least one sensor with a controller at a remote, out of water, surface position;

sending the control signals from the surface position to the at least one sensor at an underwater position along at least one transmission line;

producing a signal with one of the at least one sensor;

sending the produced signal to a processor at a remote, out of water, surface position along the at least one transmission line; processing the produced signal with the processor.

25. The method according to claim 24, wherein the method uses the apparatus according to any one of claims 1 to 18 or the kit according to any one of claims 19 to 23.

26. A method for conducting underwater sensing substantially as described herein.