Unmanned submersible vehicle with on-board generating capability
An unmanned submersible vehicle which has the capability to be remotely operated is powered by on on-board battery. The battery is recharged while the vehicle is operating by a turbine driven by the flow of water past the vehicle. The vehicle may also be coupled to a base station by a cable for control purposes. The cable is spooled on a cable spool mounted in or on the vehicle, so the vehicle unspools the control cable as the vehicle moves away from the base station.
This application claims priority to provisional application No. 60/670,375 entitled “UNMANNED SUBMERSIBLE VEHICLE WITH ON-BOARD GENERATING CAPABILITY”, filed Apr. 11, 2005.
FIELD OF INVENTIONThis invention relates generally to unmanned submersible vehicles, and specifically to such vehicles for inspection and/or repair of structures such as pipes, tunnels, or aqueducts from a location internal to the structure.
BACKGROUNDUnmanned submersible vehicles are well known. These submersible vehicles are remotely or autonomously operated. The remotely operated vehicles are linked to a head end or base via a cable carrying signals to and from the base and in some cases carrying electric power from the base to the vehicle. Such vehicles have a number of uses, for instance inspecting underwater structures, exploring the bottom of the ocean, etc. One particular use is inspecting the interior of large diameter pipe structures such as water conduits. Also such vehicles are used for repair of such structures. Typically, such structures are aqueducts, tunnels, shafts, outfalls, conduits and other fluid carrying structures where internal access is difficult. Accessing such structures require long horizontal excursions from the access points. It is desirable to perform inspection and/or repair under submerged conditions, that is when the structure is carrying water rather than attempting to dewater the structure. In many cases, such structures cannot have their operation interrupted in order to dewater them, for instance when they are carrying water supplies to a municipality. In some cases dewatering of the structure may cause damage.
Existing remotely operated vehicles have been developed to provide for submerged horizontal penetrations up to e.g. six miles long. These remotely operated vehicles are controlled via an umbilical cable and provide real time information from the vehicle back to the base through the umbilical. Autonomous underwater vehicles on the other hand are untethered (no cable) and capable of long distance horizontal/vertical excursions. However, it is often difficult to maintain real-time communication to the base through the body of water or other fluid particularly if the submerged system is a tunnel or aqueduct. The use of autonomous vehicles is not indicated for use in this situation with the presently existing capabilities of through water data transmission if real-time information transfer is required over significant submerged tunnel distances.
The typical remotely operated submersible vehicle is powered and controlled through the umbilical cable pulled behind the vehicle. Even a neutrally buoyant cable creates considerable drag which must be overcome by the forward thrust of the vehicle. Waterflow within for instance an aqueduct (tunnel or conduit) in which the vehicle is traveling and/or any bends in the aqueduct which allow the tether to contact a tunnel wall further increase the cable drag. Long tunnel penetrations require a very lengthy umbilical cable, for instance miles long. Further, the umbilical must include an electrical conductor if it is to carry electric current to the vehicle for powering same. The size and weight of the conductor can be increased for a long umbilical, or the electric voltage can be increased to transmit power through the umbilical. However, each of these options creases problems for the vehicle. For instance, conductor weight can be offset by umbilical floatation. However, that increases the umbilical diameter, surface area and drag. Increasing the voltage of the supplied electric power creates problems with insulation, heat, and durability of the umbilical. Hence in general the horizontal capability (travel distance) of such remotely operated vehicles is limited by the umbilical cable and its handling systems.
SUMMARYThis disclosure is directed to an unmanned submersible vehicle which includes features to provide extended horizontal penetration capabilities, control and data transmission and enhanced operational flexibility, for instance, within submerged conduits such as aqueducts.
Most conventional remotely operated vehicles operate by towing a cable behind them, which supplies the power and also two-way data transmission. As pointed out above, in spite of the use of neutral buoyancy cables, there is an increase in drag dependent upon the surface area of the cable, water flow conditions, and contact with the interior tunnel or conduit surfaces. In accordance with this disclosure, a remotely operated vehicle carries, in addition to a conventional onboard electrical power source such as rechargeable batteries, the capability to recharge those batteries by an onboard generator which is operated by water flow within the tunnel (conduit, etc.). This has several advantages, since as a result the cable itself can be very thin since it only need carry data signals rather than electrical power. Typically this is a fiber optic cable including also strengthening members and abrasion protection as well known in the field. There may be a very small diameter electrical conductor in the cable to trickle charge the vehicle's onboard rechargeable batteries. In other cases, the conductor may be entirely omitted from the cable. Since the cable is relatively thin and light, long lengths of same can be easily pulled by the remote operated vehicle as necessary. Alternatively, it is possible to store long lengths of the relatively light and thin cable onboard the vehicle instead of dragging it behind. In this case, the onboard length of cable is typically on a spool and the cable is unspooled as the vehicle travels down the conduit away from the base. If desireable, it can be subsequently respooled as the vehicle returns to its base. Alternatively, the cable can be retrieved and extracted from the conduit separately.
This configuration allows water flow through the conduit to be maintained while the submersible travels through same. For the generator to operate, the vehicle can be temporarily fixed in a stationary position or slowed within the conduit. This is accomplished in accordance with this disclosure by providing a locking mechanism such as a strut extending from the vehicle which pins the vehicle on the conduit wall. In this case the vehicle itself may have negative buoyancy and so ride along the bottom of the conduit, or have neutral or positive buoyancy. Hence the extended strut extends to a far wall of the interior of the conduit fixing the vehicle in place on the wall while the turbine operates to recharge the battery. During this time, there is no need to alter normal water flow through the conduit. Advantageously with this configuration, inspection and repair work using the vehicle within the conduit is not limited to times when the tunnel is not carrying water. Of course this is a major advantage since in many cases shutting down the water flow in the conduit for other than short periods is undesirable. Moreover, the locking mechanism can position the vehicle in a particular position for inspection purposes while normal water flow is resumed. This allows observance of faults in the conduit such as cracks during conditions of normal tunnel flow, which is often useful.
The present vehicle thus has a relatively long range so that it can operate far away from its base, as determined by the length of onboard cable. This allows simplified operation since there is no need for frequent introduction and removals of the vehicle to the conduit. Of course, for many conduits the access points are widely spaced apart and it is not possible to operate a vehicle having a short range within such conduits.
The cable which in accordance with this disclosure is unspooled from the vehicle rather than being dragged behind creates advantages for tunnel and conduit penetration. Such a cable which is unspooled rather than dragged is less susceptible to fouling on internal obstacles. Also since it is not laid under tension, retrieval of the cable when it is fouled is easier than if it is jammed in place on an obstacle when dragged as in the prior art. Additionally, such a cable that is unspooled rather than dragged behind the vehicle need not be neutrally buoyant but instead may be negatively buoyant and hence lay along the conduit floor. Further, such contact with the floor of the conduit by the cable typically reduces friction on the cable during intervals of water flow within the conduit. The vehicle can exit the conduit by progressing back along its path and respooling the cable previously laid out. Typically the cable is spooled upon a cable spool in the vehicle which is driven by an electric motor also within the vehicle for unspooling and respooling purposes. A conventional spool cable brake may also be provided.
Further considered in accordance with this disclosure is the possibility of vehicle operational failure. For instance, if the vehicle cannot retreat and respool its cable for reasons such as a fouled cable, the vehicle has the capability using an onboard guillotine (severing mechanism) to sever the cable. This condition may be determined by an onboard controller/microprocessor. The severing may also be commanded from the base if the vehicle is still in contact with the base via the cable. In any case, upon loss of base contact or severing of the cable, the vehicle automatically reverts to a preprogrammed autonomous underwater vehicle mode and then proceeds to exit the conduit under its own control. The damaged or severed cable may be removed separately. In this case, additionally if for some reason if the vehicle cannot exit the conduit in the normal autonomous underwater vehicle mode, it may be programmed to deploy a drogue which will remove it from the conduit under the force of normal conduit water flow. This is important since one cannot leave a disabled vehicle in the conduit.
BRIEF DESCRIPTION OF THE DRAWINGS
In any case, in
For control purposes, at the rear of the submersible 12 is port 28 from which emerges the cable 30 which typically carries control signals to and from the submersible 12. Typically this is a fiber optic cable with strength members and an outer coating for protection purposes. Cable 30 may also include an electrical conductor as discussed above, but not necessarily. If there is an electrical conductor, it may be of relatively smaller diameter so the cable is relatively thin, flexible and light. At the front of submersible 12 is a pair of manipulator devices of which only the left most 32a is visible. There is a similar manipulator device on the front right side of submersible 12, not visible here, and additional general purpose and/or special purpose manipulators and/or work devices can be mounted elsewhere upon platform 14.
Extending outward from the housing 16 are two struts or props or jacks 36a, 36b each terminating in a prop extension 40a, 40b. As shown, extensions 40a, 40b are curved so as to fit snugly against the interior wall of the conduit. (Typically the interior of the conduit is curved.) Extensions 40a, 40b may include somewhat soft material such as plastic and/or rubber to avoid damaging the interior wall of the conduit. The telescoping props 36a, 36b are rigid and thereby the extensions 40a, 40b fit snugly against the interior of the pipe when the submersible 12 is to be stationary. Hence, when it is intended to make the submersible stationary, tracks 20a, 20b, etc. rest against the bottom wall of the pipe interior and the props 36a, 36b with their extensions 40a and 40b pin the submersible 12 in a particular position in spite of the water flows through the conduit. The struts depicted are but one possible embodiment of a jacking system deployed to fix the vehicle in stationary position within the tunnel. It is to be appreciated that submersible 12 is typically used when the conduit is carrying water at a relatively large rate of flow. Of course, this is not necessarily the case and the submersible 12 will also work in a dry aqueduct or pipe or conduit.
Submersible 12 makes use of the potential energy of the water traveling under pressure in the tunnel, pipe, conduit, aqueduct, etc., and the submersible is arranged so that it generates electric power from the water flow whenever the velocity of water (or other fluid) in the conduit differs from that of the speed of the vehicle. Hence, there are provided extending outside the housing 16 turbine devices 44a, 44b, mounted respectively on supports 46a, 46b. In this case, the turbines 44a, 44b extend well out of the housing. In other embodiments, they may be built wholly or partially into the housing and connected to the exterior through flow channels. Each turbine includes an impeller, further detail of which is described below. The impeller rotates when the speed of the vehicle through the conduit differs from that of the water flow therethrough. Hence the water flow will spin each impeller which may be connected mechanically through its support 46a, 46b to a generator which generates electricity thereby and the electricity then is typically coupled into the rechargeable battery (not shown, but conventional) present in housing 16. In other cases, each impeller has an integrated generator to generate electricity which then is coupled to the rechargeable battery through electrical conductors extending through supports 46a, 46b. Such small turbine/generator combinations are well known in the electrical engineering field. In other embodiments of this vehicle, the turbines may be powered and used as thrusters to maneuver the submerged vehicle.
The self-charging/re-charging design of this vehicle is obviously not limited to tunnels or conduits. The use of differential water flow velocities for power generation is equally applicable to prevailing current situations, tidal bores, and/or other situations involving water movement.
The use of propulsive-thruster motors as part of a non-tracked neutrally buoyant underwater vehicle will allow the machine to be propelled through the water in the “thruster mode” or alternatively recharge the vehicle in the “generator mode”. Large diameter low-pitch propellers may be used for vehicle locomotion then the propeller pitch can be remotely altered to become a low-speed high-pitch electrical generator. Appropriate solid state permanent magnet motor-generators are readily available technology.
The other structure of interest in
Hence, in accordance with this disclosure the submersible has the ability to stop its progress through the conduit and remain stationary within the conduit. The water flowing around the submersible spins the impellers in turbines 44a, 44b to generate electrical current to recharge the battery. In other embodiments the submersible may carry devices to slow its progress relative to the flowing water. In that case, the struts 36a, 36b need not be deployed in order to stop the vehicle in the conduit.
Charging the batteries may take place continuously or at intervals. Typical slowing devices could be several long, highly flexible members that attach to the submersible and trail behind it and make contact with the conduit walls. Such springy “whips” or flexible members may be affixed to the housing 16 so that they are angled off the horizontal, and can be controlled and adjusted remotely, that is, from the control base. This ability allows the bearing force against the walls of the conduit to be increased or decreased and thereby alter the speed of the submersible relative to the water flow. Also, in the case of a tracked submersible which travels on the bottom, or even the top of the conduit, the weight or balancing of such a submersible may be remotely controlled by allowing water to enter or be pumped out of the tanks 18a, 18b to achieve optimal flow differential speed in order to control both the speed of travel and the amount of electrical charging continuously.
Note that the particular configuration shown in
Since the
The
To give an idea of scale in one embodiment, each impeller is about 20 inches in diameter (50 cm). The size is dependent upon the use and power needs of the submersible.
Additionally provided associated with submersible 12 is a cable severing mechanism. This is not shown in the earlier figures for simplicity, but is in
It is understood that the submersible 12 typically carries onboard intelligence, including, for instance, a microcontroller and/or microprocessor, which conventionally actuates various of its mechanisms. Also submersible 12 may be controlled through remote signals which are processed by the microprocessor/microcontroller. As explained above, in event of failure of the cable the submersible operates autonomously (under its own control), at least on a limited basis. The cable severing mechanism as described above is intended to be operative when the cable is fouled and cannot otherwise be retrieved or freed and it is desired to allow the submersible 12 to continue its movement autonomously through the conduit for recovery.
This disclosure is illustrative, not limiting; further embodiments and modifications will be apparent to one skilled in the art in light of this disclosure and are intended to fall within the scope of the appended claims.
Claims
1. An unmanned submersible vehicle, comprising:
- a submersible housing;
- a rechargeable battery system located in the housing;
- a turbine associated with the housing, whereby the turbine is driven by a flow of water past the housing; and
- a generator coupled to the turbine, wherein the generator is electrically coupled to recharge the battery.
2. The vehicle of claim 1, wherein the turbine includes an impeller external to the housing.
3. The vehicle of claim 1, wherein the turbine is at least partly internal to the housing
4. The vehicle of claim 1, further comprising:
- an axle with wheels or tracks mounted external to the housing; and
- a motor in the housing and coupled to drive the wheels or tracks;
- wherein the motor is electrically coupled to the battery.
5. The vehicle of claim 1, further comprising a member extensible outward from the housing thereby to bear against a surface to inhibit movement of the vehicle relative to the surface.
6. The vehicle of claim 5, wherein the member terminates in a curved portion.
7. An unmanned submersible vehicle, adapted to receive and/or transmit signals along a cable coupled to a base, the vehicle comprising:
- a submersible housing;
- a cable spool mounted to the housing; and
- a spool control coupled to the cable spool, whereby the cable in operation unspools from the cable spool as the vehicle moves away from the base.
8. The vehicle of claim 7, wherein the spool control includes a cable brake.
9. The vehicle of claim 7, wherein the cable spool is mounted external to the housing.
10. The vehicle of claim 7, wherein the cable spool is mounted internal to the housing and the cable passes from the cable spool through a port defined in the housing.
11. The vehicle of claim 7, wherein the spool control includes a motor coupled to rotate the spool.
12. The vehicle of claim 7, further comprising a traveler mounted to the cable spool and movable along the cable spool.
13. The vehicle of claim 7, further comprising a length of negatively buoyant cable adapted to be spooled on the cable spool.
14. The vehicle of claim 7, wherein the cable includes an optical fiber.
15. The vehicle of claim 7, further comprising a severing mechanism mounted adjacent the cable and adapted to sever the cable.
16. The vehicle of claim 15, further comprising a controller in the housing, wherein in normal operation the controller is in communication with the base location via the cable, and upon a severing of the cable, the controller autonomously controls operation of the vehicle.
17. The vehicle of claim 16, wherein the controller is operatively coupled to the severing mechanism, thereby to sever the cable upon determination by the controller of predetermined conditions.
Type: Application
Filed: Apr 6, 2006
Publication Date: Feb 1, 2007
Inventors: Ian Griffith (Oakland, CA), Rene Nuytten (North Vancouver), James Clark (Harvard, MA)
Application Number: 11/400,432
International Classification: B63G 8/00 (20060101);