WO2007040411A1

WO2007040411A1 - Target seeking unit for release at deep water, particularly in the form of a node

Info

Publication number: WO2007040411A1
Application number: PCT/NO2006/000344
Authority: WO
Inventors: Vidar Hovland
Original assignee: Vidar Hovland
Priority date: 2005-10-06
Filing date: 2006-10-06
Publication date: 2007-04-12
Also published as: NO20054604L; NO20054604D0

Abstract

Autonomous homing unit in the form of a deployment unit for release at deep water at a predetermined first position and controlled displacement from there using own energy, to the position of a predetermined target. The unit comprises a main part (1), a control unit (7), a payload (5), a power source (6), means for manoeuvring (2) for course correction, input/output circuits (3), and auxiliary elements (4, 11). After being released from a vessel it sinks under its own gravity down to the ocean floor (8) and manoeuvres simultaneously towards a target, using means for manoeuvring (2), and at a position in or near the targets it executes predetermined functions, particularly collection of seismic data which it after some time delivers at the surface, after being recovered or ascending under self activated buoyancy.

Description

Target seeking unit for release at deep water, particularly in the form of a node

Introduction target seeking unit which is in particular in the form of a deployable unit of the type that is frequently called a node, that is a unit that can be remotely-, locally- or self activated and particularly suited for release and autonomous navigation to a predetermined position at the ocean floor at the deep water, down to approximately 5 000 meters for serving as a listening station or similarly, particularly for continuous collection of seismic data.

Background

On deploying units of this type of frequently called nodes, for collection of information from the ocean floor at great depths one has applied the different means such as remotely operated or unmanned vehicles of the type ROV (remotely operated vehicles) and AUV (autonomous underwater vehicles) and manned miniatures submarines, but this is both time consuming and expansive. Divers have frequently been used at shallow depths, but this has been problematic at greater depths since deep water diving entails greater risk and is therefore limited to moderate depths.

From the known art there is the patent US 2003 0 075 096 Al describing an apparatus for controlling the motion of an object in water. A processor is used for accurate regulation of the buoyancy of the apparatus and its functions can cover maintenance of predetermined depths in the water, and ascent and descent at a given speed. A remotely operated vehicle can be connected to said apparatus in order to aid in displacement of it and then makes available the power needed for displacing the object horizontally while the apparatus itself can supply the necessary vertical power for vertical replacement. The apparatus can be controlled from an operated on the surface of the water and signals for communication can be transmitted over a cable, radio signals, acoustic waves, optical signals or by other means.

The apparatus can also be part of a platform that is operating independently as is the case for vehicles of the type AUV as these follow a pre-programmed series of operations based on processor control and is additionally often using artificial intelligence. In that case the apparatus can be a component that belongs to the vehicle itself and controls it s position and displacement within its own control system.

Patent US 2004 0 059 476 Al discloses a device and a method for transmitting data from an autonomous underwater vehicle to a central above surface. Data is transmitted using several units or cylinders for storage of packets of data and transporting up to the surface for processing in the central. After data transmission, the device releases the balloon and sinks to the ocean floor. The purpose in sending up units containing information to be received continuously is to maintain the intervals for such released information short, particularly when collecting data from pipelines and where for instance leakages will have to be reported immediately. Every unit that is released to the surface with information is released by entering gas into a balloon which initially is stored as a flat and empty membrane but during the entering of gas, expands and achieves a larger volume with the associated buoyancy. The gas is received from gas generator in the form of a high-pressured tank, and the gas is particularly compressed helium.

The patent also discloses another related technique using autonomous underwater vehicles for collecting data stored in electronic stores and can be read out when the vehicle is returning to the surface, or whether the vehicle is entered into a docking station which is installed at the ocean floor and there delivers its information. Such docking for collecting data down to depths of 6 700 metres is moreover disclosed in US patent 5 687 137, and US patent 5 995 882 discloses an autonomous underwater vehicle for oceanographic measurement where a vehicle is arranged for gathering and storing data and connected to a receiver for a global positioning system (GPS), a radio transmitter and receiver and electronics for determining position and passing this on when the vehicle has reached the surface.

In addition, known is the use underwater vehicles such as miniature submarines and remotely operated or programmed units particularly for inspection maintenance and repair of equipment related to pipelines and oil drilling. On such project is the hybrid vehicle swimmer, made in cooperation between Statoil, FMC Kongsberg Subsea and the French company Cybernetix, a project that received the inventive prize in 2001 for North Sea activities. Under the umbrella organisation Cybernetix the project ALIVE has been developed, that is "autonomous light invention vehicle", and this vehicle has been placed on the surface from an auxiliary vessel and navigates autonomously down to an area near the ocean floor. The purpose is particularly to assist a submarine in that area. Contact is made with a submarine, information is gathered and stored, and after completing the mission the vehicle again ascends to the auxiliary vessel.

In an overview made by ESONET (the European Sea Floor Observatory Network) that can easily be found on the Internet at www.ifremer.fr/esonet discusses a number of known solutions and development programmes for long term surveillance of maritime environments and parameters at and on the ocean floor. This regards for instance deployment of platforms and observatories at the ocean floor down to about 5 000 metres. On such observatory is called ALIPOR ("Autonomous lander instrument platform for oceanographic research"). Such stations are typically autonomous in terms of energy supply and recording of data, and the recording period can extend from 6 to 12 months. European projects GEOSTAR regards collection of geophysical data and with increased capacity using multi function sensors. Transmission of data can take place at near real time using an acoustic connection between the station at the ocean floor and a buoy anchored nearby which in turn has a VHF- or satellite connection to a main central. An equivalent system OFOS is used in Adriatic Sea and continuously

5 monitors sediment pressure and seismic activities.

These stations or observatories of autonomous type regarding power supply are generally released into free fall in the water in such a way that the position at the ocean floor can be somewhat random. For the project GEOSTAR a mobile docking station was therefore used that can manoeuvre on the ocean floor and choose correct position.

I₀ Remotely operated vehicles (ROV) are moreover used for displacing to a desired location on the ocean floor and the remote operation can for instance be performed using cable.

An ocean floor observatory (OFM) which in the simplified case can be called the node, will have to comprise different types of equipment, and the internet site is www.dt.insu.cnrs.fr section OFM describe what typically is required for a somewhat larger station, that is a number of sensors that will have to operate at the depth of 5 000 metres and where the observatory will have to be completely autonomous over a period of at least two years. A such slightly larger node can have several modules for the different sensors, instruments of the time type inclinometer, gyrocompass, sensors for

20 electric field strings, and a sensor for synchronizing of signal from the various sensors, collection of data, storage, compression circuits for data, surveillance circuits for battery and input/output circuit for transmission of information and energy supply, in the cited case using a cable.

US 2005 0099 891 discloses a system for positioning of vehicles at moderate

2₅ depths, in that the vehicle has a receiver and at least two transmitters. The patent discloses several problems related to positioning such as underwater acoustic disturbances from foreign systems or even from fish or animals in the water limiting the coverage as a result of the physical properties at the deep water and where the transmitting signals easily can disturb the receiving signals, and the importance of 0 knowing currents, temperature, salinity and other for correction of direction and propagation velocity of signals in the water.

US patens 5 816 874 and 5 606 138 further discloses known different systems for collection of water data and communication under water, particularly between a node or equivalent for collection of data and a central position.

3s From the known art regarding general manoeuvring using fins and the like, the rocket and missile technology applies a series of solutions for homing. Data for the target can be partially supplied in advance and partially be supplied during the course as correction values in that the rocket or the missile has receivers/sensors and means for own manoeuvring. Overview of the deployment unit of the invention and drawings of a typical embodiment

The background of the invention is the known art disclosed above and particularly that the method of deploying units at very large depths has disadvantages that this invention seeks to overcome. This invention therefore discloses a unit of the type node that can home in autonomously towards a target or be controlled from a signal or another type of command.

The purpose is accomplished in the deployment unit as specified in patent claim 1, that is an autonomous homing unit for transmitting from a first position and controlled displacement from their using own energy to the position of a target, comprising a main part, a control unit, a payload, a power source, means for manoeuvring for course connection, input/output circuits and secondary units.

The unit is particularly characteristic in that it is in the form of a deployment unit arranged for release at deep water from the first position at the surface of the water, sinking under gravitational force from its own mass down to the ocean floor, and simultaneously manoeuvring in towards the position of the target, using means for manoeuvring, and use of particular functions of the unit at its final position wherein this is at or deviate somewhat from the position of the target. The payload of the node can be or be connected to a central or a control unit which through pre programming activates particular units after a certain time at a certain position, after registering of particular activities, after a predetermined amount of registered data, at predetermined reduction of the reserves of the power source, at external mechanical influence such as from a submarine at the deep water or manual operation at shallow water, and others.

More features of the unit are disclosed by the subsequent claims and the description below.

The node of the invention is more closely described below, while also referring to the drawings where Fig. 1 shows the principles of the unit and its components.

Description of a preferred embodiment

Fig. 1 discloses a typical embodiment of the deployment unit or the node of the invention, in principle a homing unit as indicated by the title, but particularly suited for release down to ocean floor at great depths, and Fig. 2 discloses a similar unit in the more elongated form and with feet for stable positioning at the ocean floor and at the moment connected to the hook on a buoyancy unit that will bring it to the surface.

The unit is a homing unit, but in addition to being called a node it can also be called a deployment unit since it can actively navigate in towards a predetermined target at the ocean floor and there serve as a deployed station forming a nexus in a larger surveillance or data logging grid. The unit has a main part 1 that can form a solid shell to resist great pressures at the ocean floor 8 (see Fig. 2) and can have a reinforced internal frame. For controlling the node on its way down into the water, it has means for manoeuvring 2 shown in the example as fins on the sides. Such means for manoeuvring can also comprise thrusters, rudder, nozzles and more. A central control unit 7 is illustrated on Fig. 1 and can be said to be the brain of the node. A payload 5 is connected to the control unit and can assist in tasks for registering, calculations, storage and control, for the various functions that the node is to perform both on the way down to the ocean floor and when it has found the correct position and there register the surroundings particularly collecting seismic data. Information regarding the current position of the node is stored continuously in the payload 5 which also can comprise a storage unit, and this information is extracted from sensors of the type accelerometers , gyro instruments and other instruments belonging to inertial navigation, or information entered using signals, in that the node has a transponder 3 or other types of input/output circuits for communication with the surroundings. In this way, the circuits can be informed of a set of connections or a fixed connection for use of signal cable for commands and transmission of the data. A power source 6 ensures that the node is autonomous, and the power source can be in the form of batteries for electrical power.

When the node has completed its mission on the ocean floor, for instance remained there for a predetermined period of time and gathered information or performed a surveillance mission, it can, on an external signal, on it own activation or as results of other criteria, start the ascent to the surface. There it can emit gathered information and be ready for a possible new deployment. The ascent can take place using own means, illustrated as an ascent unit 4 at the top of the node on Fig. 1, or using external buoyancy unit, shown as 4 on Fig. 2. For use of such external lifting power the node has an element in the form of a hook or hoop 11 as indicated on Fig. 2, shown here as an example.

The node can also after completed mission be picked up by a remotely operated underwater vehicle (ROV) or using a line that has been connected to it all this time.

In connection with the control unit 7 and the payload 5 there can be arranged an input/output unit for data transmission.

An example of the use the node or deployment unit of the invention can be as follows: The node is programmed for performing particular functions, and the programming comprises positioning of auxiliary vessel it is released from and the position of the target, that is the place to which it should home in and remain at for performing particular functions. The node is released into the water and sinks under force of gravity from its own weight. The drop to correct or almost correct position can take place by different means, comprising using a wire, control of external vehicle or autonomously in that the buoyancy unit comprises sensors for continuous position determination (accelerometers s or similarly) and means for manoeuvring and correction of attitude (fins, rudders, thrusters, nozzles and others).

From entered data regarding continuous position, either from own navigational equipment or entered externally, the means for manoeuvring 2 of the node is used for course correction, optionally with additional use of own propulsion if installed. o Updated positions can also be entered from or supplied from a vessel on the surface.

The node lands in approximately correct position that is that of the target, and commences the functions to be performed, such as data logging. If the registered or the calculated position deviates from the pre programmed coordinates for the site position, that is that of the target, criteria can be entered regarding the functions to be performed s where the node has landed or if it instead should ascent to the surface again for a new attempt. It should also be noted that the node can have registered a position deviating significantly from that of the decided position, while in reality it could be very close, the reason being accumulated errors during the continuous registration during descent, for instance due to strong ocean currents or unexpected obstacles. 0 Nevertheless the start can be delayed to a predetermined point in time or take place on command from the surface. Activation of the different functions can also be controlled externally for instance as a result of various actions. One example is when the node is used for surveillance of a pipeline where such an event can be a change of the situation for instance a leak. ₅ The node can ascend to the surface after completed mission using its own buoyancy and in this case an auxiliary element is activated reducing the weight of the node by releasing ballast and or increasing volume by expansion of an element suited for this purpose, or connection of an external buoyancy unit being called for or connected. The node can in this case be attached to such unit using quick release and/or 0 a hook, hook or others. Such an attachment is shown in Fig. 1 shown in a simple schematic embodiment at the top of the node, but it could in principle be part of an attachment mechanism at any place. The position during ascent is preferably also monitored such that the node can easily be located on the surface.

At the surface, particularly on the auxiliary vessel on recovering the node, it is s unloaded for data, batteries are replaced or recharged, and it is once again ready for use.

The deployment or homing unit in the form of the node can naturally also take on different shapes, for instance have a more elongated form such as a submarine, which is indicated on drawing on Fig. 2.

Claims

P a t e n t c la i m s

1. An autonomous homing unit for deployment from a predetermined first position and controlled displacements from there using its own energy, to a predetermined position of target, comprising: a) a main part (1), b) a control unit (7), c) a payload (5), d) a power source (6), e) means for manoeuvring (2) for course correction, f) input/output (3), and g) auxiliary elements (4, 11) , characterized by being the form of a deployment unit devised for:

1) deploying at deep water from the first position at the surface of the water,

2) sinking under gravity down to the ocean floor (8) and simultaneously

3) manoeuvring towards the position of the target, using means for manoeuvring (2), and 4) executing particular functions at the final position of the unit where this is equal to or deviates from the position of the target.

2. Deployment unit according to claim 1, characterized in that the means for manoeuvring (2) comprise circuits for registering the current position of the unit from the first position at the site for release, to the final position at rest near or in the target, wherein the current position is continuously calculated in relationship to the first position using data on the route towards target, comprising data from systems for inertial navigation and data from sensors for registering parameters in the environment.

3. Deployment unit according to claims 1-2, characterized in that the particular functions comprise registering and storing of seismic data on the ocean floor (8).

4. Deployment unit according to claims 1-3, characterized in that the particular functions comprise termination of collected data, preparation for ascent to the surface, and ascent to release the collected data and optionally preparation for new deployment.

5. Deployment unit according to claim 4, characterized in that the preparation for ascent comprises activation of a particular auxiliary in the form of a buoyancy unit (4) and/or connection to an external unit that can be activated, including a remotely operated vehicle (ROV).

6. Deployment unit according to claims 1-5, characterized in that the means for manoeuvring comprise fins (2), thrusters and similarly for course correction while the unit is sinking towards the ocean floor (8).

7. Deployment unit according to claims 1-6, characterized in that auxiliary elements comprise a device for attachment (11).

8. Deployment unit according to claims 1-7, characterized in that the payload comprise a storage unit (5) for data and is attached to the control unit (7), where this is arranged for using pre programming for initiating particular functions based on external and internal conditions, including lap time, registering of particular activities, after registering and storing a predetermined amount of data, by a given reduction of the remaining energy of the power source and others.