US20070022935A1

US20070022935A1 - Unmanned submersible vehicle with on-board generating capability

Info

Publication number: US20070022935A1
Application number: US11/400,432
Authority: US
Inventors: Ian Griffith; Rene Nuytten; James Clark
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-04-11
Filing date: 2006-04-06
Publication date: 2007-02-01

Abstract

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.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

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 INVENTION

This 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.

BACKGROUND

Unmanned 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.

SUMMARY

This 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

FIGS. 1A, 1B and 1C show overall views of a submersible in accordance with this disclosure;
FIG. 2 shows a detailed view of the turbine portion of the on-board electric power generator in accordance with this disclosure;
FIGS. 3A and 3B show detailed views of the on-board cable spool and associated mechanisms in accordance with this disclosure;
FIG. 4 shows a detailed view of the extendible strut (prop) in accordance with this disclosure.
FIGS. 5A and 5B show detailed views of a guillotine mechanism for severing the cable in accordance with this disclosure.

DETAILED DESCRIPTION

FIG. 1A shows an overall partially cut away view of relevant features of a submersible 12 in accordance with this disclosure. This is likely a remotely operated vehicle but may be in another embodiment or aspects of its operation an autonomous underwater vehicle. Only relevant features are shown here. Conventional features including the rechargeable battery, pumps, valves, electric motors, inspection apparatus (for instance illumination and video cameras), signal processing circuitry etc., are not shown for simplicity. This particular submersible is intended primarily for use in closed spaces such as aqueducts, conduits, pipes, etc. The depicted version crawls along the interior bottom of a pipe or conduit. However, in other embodiments it is not so limited. The vehicle size is a matter of design choice depending on the diameter of the particular conduit/pipe in which the vehicle is to be used. Typically the vehicle is significantly smaller in diameter than the pipe in which it is intended to operate. Actual inspection typically takes place through the vehicle's housing or with ancillary systems such as video cameras, sensors, etc. In other embodiments, the submersible vehicle is also provided with apparatus for repair of flaws or faults in the conduit.
In any case, in FIG. 1A, submersible vehicle 12 includes a chassis or platform 14 to which is mounted a housing 16 which is typically sealed so as not to admit water therein. Mounted on the chassis 14 are two buoyancy (air/water) tanks 18 a, 18 b for controlling buoyancy of the vehicle, as is conventional together with associated conventional pumps, valves, compressed air supply, etc. (not shown). In one embodiment this submersible has negative buoyancy but the buoyancy may be adjustable. The submersible moves on a set of tracks; in this case, rear tracks 20 a and 20 b and a single front track 22 a are visible with the other front track being hidden. These tracks are conventionally driven by motor inside the housing 16 which is electrically coupled to a rechargeable battery. There may be independent motors provided for each track or track pair or there may be a gearing mechanism linking an electric motor to various of the tracks. The tracks also allow steerability. Instead of tracks there may be in another embodiment wheels and/or articulated legs. The tracks are conventionally driven by bogies and the tracks themselves are e.g. steel and/or rubber or plastic.
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 32 a 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 36 a, 36 b each terminating in a prop extension 40 a, 40 b. As shown, extensions 40 a, 40 b are curved so as to fit snugly against the interior wall of the conduit. (Typically the interior of the conduit is curved.) Extensions 40 a, 40 b may include somewhat soft material such as plastic and/or rubber to avoid damaging the interior wall of the conduit. The telescoping props 36 a, 36 b are rigid and thereby the extensions 40 a, 40 b 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 20 a, 20 b, etc. rest against the bottom wall of the pipe interior and the props 36 a, 36 b with their extensions 40 a and 40 b 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 44 a, 44 b, mounted respectively on supports 46 a, 46 b. In this case, the turbines 44 a, 44 b 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 46 a, 46 b 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 46 a, 46 b. 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 FIG. 1A is the cable spool 50, further details of which are given below, on which is wound a length of the cable 30 inside the housing 16. As described above, submersible 12 need not necessarily obtain its electric power through the cable which thereby can be relatively thin and light. Moreover, of course, since the submersible unspools and spools its cable 30 it need not drag a long length of cable.
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 44 a, 44 b 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 36 a, 36 b 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 18 a, 18 b 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 FIG. 1A is not limiting. For instance, while two props 36 a, 36 b are shown there may be one or three or other numbers. Similarly, while two turbines 44 a, 44 b are shown there may be one or more, depending on electrical generating needs. Also the size of these turbines may be altered.
Since the FIG. 1A submersible is typically for use in an aqueduct carrying water which has already been at least partly filtered, there is no concern in this particular embodiment about particles or debris jamming the turbines. However, if the submersible is to be used in a less benign environment, then filters/screening devices may be provided to protect the impellers in the turbines from being clogged by debris. These filters would be located on the intake side of each turbine housing. Similarly, the actual configuration of the impellers is dependent upon the relative speed of the submersible during power generation phase and hence is a design consideration.
The FIG. 1A submersible is shown in a rear view in FIG. 1B with the same structures identified with the same reference numbers. Additionally shown in this view is axle 52 which carries tracks 20 a, 20 b.
FIG. 1C shows a side partial cut away view of submersible 12 with the same structures identified with the same reference numbers. In this case the cable spool 50 is better shown, including its traveler 54 for laying the cable on the spool 50. Traveler 54 moves back and forth on horizontal tracks 74 as it is conventional with cable spools. Also provided is a cable brake not shown, but conventional. The cable spool itself is rotated by a drive motor in either the forward or reverse direction to unspool and spool cable. This motor is conventional and not shown. The cable spool drive motor is coupled to cable spool 50 by a mechanical linkage or may be a direct drive. This motor is also powered either directly or indirectly by the rechargeable battery in housing 16.
FIG. 2 shows detail of one of the turbines 44 a on its telescoping prop 46 a. The telescoping is under control of an electric motor or hydraulics located within housing 16 and not shown. At certain times during operation of the submersible, for instance, when it is introduced or removed from the pipe, it would be desirable to collapse the props so that the turbine portion 44 a is as close as possible to the housing so that it is unlikely to foul. In this case, as shown the turbine 44 a is coupled by its extensible prop 46 a to a base 62 which is mounted to the housing 16 or chassis 14. The turbine 44 a includes outer portion 64 inside of which is mounted a hub 60, which carries the actual impeller blades 66. As stated above, in some embodiments, hub 60 includes the actual electric generator driven by the rotation of the impeller 66, and the generator in hub 60 is coupled by an electrical connection through strut 46 a to the battery for recharging purposes. Of course, conventional circuitry for power processing in terms of current and voltage regulators, etc., may be provided to protect the battery.
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. FIG. 3A shows an enlarged partial view of submersible 12 showing chiefly the cable spool apparatus with the same reference numbers as in the prior figures. The cable spool 50 has end pieces 70 a, 70 b. End pieces 70 a, 70 b accommodate the cable of which in this case only a single strand 30 is shown. It is to be understood that typically the cable spool carries multiple layers of spooled cable 30 extending from end piece 70 a to end piece 70 b. Traveler 54 travels back and forth, horizontally, on the horizontal members 74 to locate or remove the cable from the spool. Such arrangements are well known in the field. Traveler 54 may include an idler 55. Cable 30 also passes over idlers 57 and 59. The right hand end piece 70 b is driven by an electric motor and/or gear or belt linkage not shown to rotate the cable spool. The cable spool rotates in either direction for spooling and unspooling the cable consonant with movement of the submersible 12. Also provided is a cable brake as is conventional, incorporated in the traveler 54 or which is a brake on the right hand end piece 70 b. Further detail of the cable spool arrangement is shown in FIG. 3B with identical reference numbers to that of FIG. 3A. Also shown are supports 82 a, 82 b for respective end pieces 70 a and 70 b where the supports 82 a, 82 b are attached to the chassis 14 or housing 16 in to hold the cable spool assembly.
FIG. 4 shows detail of props 36 a, 36 b with respective extensions 40 a, 40 b and a common base 90 which is fixed within the housing. Other arrangements for fixing the props are possible. Telescoping of the struts 36 a, 36 b is accomplished by electric motors or hydraulic means with a suitable locking mechanism if needed to keep the struts extended. Typically, when the submersible 12 is moving through the pipe, the struts are collapsed and are extended and locked when it is desired to fix the submersible into position in the conduit. The bottom surface of the submersible 12 or tracks or skids then would rest on the conduit floor. The submersible 12 may have positive buoyancy, in which case it might ride along the top or sides of the conduit. In any case, struts 36 a, 36 b are used to fix the submersible into position. Hence, they are not limited to a negative buoyancy submersible. To give an example of scale, in one embodiment when fully extended each strut 36 a, 36 b is approximately six feet (2 meters) long. This would accommodate a submersible for use in a conduit which is approximately 8 to 10 feet in diameter; that is, 2½ to 3 meters. Of course, none of these dimensions are limiting.
Additionally provided associated with submersible 12 is a cable severing mechanism. This is not shown in the earlier figures for simplicity, but is in FIG. 5A, which is a partial cut away view showing structures similar to those of FIG. 1A, including the horizontal members 74 on which the cable traveler rides, and a portion of the cable 30 passing through the severing mechanism (guillotine) 96. In this case the severing mechanism 96 includes framework 100 attached to housing 16. Framework 100 carries vertically traveling blade 102, which is actuated by member 106, coupled to an actuator 108 moving vertically. FIG. 5B shows additional detail of the severing mechanism 96 identical to that of FIG. 5A, also showing the horizontal support 112 which allows member 106 to pivot. Actuator 108 rides in a hydraulic or other type of actuating cylinder 118 horizontal member 112 pivots within pivot housing 114. Of course, these details of the severing mechanism are merely illustrative. Cable 30 passes through port 110 in housing 100 with the blade 102 passing down into the port 110 to sever cable 30 upon command.
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.