Efficient undersea charging for autonomous undersea vehicles

Abstract

To provide a docking / charging module for efficient undersea charging of an undersea autonomous vehicle.SOLUTION: A docking / charging station 602 of an undersea autonomous vehicle UAV 750 has a housing that can be docked with the undersea autonomous vehicle and establish data and power connections between a data exchange module 706 and the undersea autonomous vehicle. A battery 704 mounted on the station is charged from a submarine cable (branch cable 104) having a power conductor, and charges a battery 752 of the undersea autonomous vehicle via a power connection when the undersea autonomous vehicle docks or approaches the docking / charging station.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 042886, filed June 23, 2020, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to the field of undersea autonomous vehicles (UAVs), and in particular to charging the batteries that power these vehicles. [Background technology]

[0003] Underwater autonomous vehicles typically comprise robots that operate independently underwater. Such vehicles may be remotely controlled or controlled by onboard software to perform specific tasks. UAVs are deployed to perform a variety of tasks in the commercial, research, and military sectors. For example, the oil and gas industry can use UAVs to draw detailed maps of the seafloor before installing deep-sea infrastructure or pipelines. Scientists can use UAVs equipped with various sensors to measure various aspects of the undersea environment. The military has many applications for UAVs, including intelligence gathering, surveillance, reconnaissance, and wartime activities (e.g., payload delivery and mine clearance).

[0004] UAVs are typically powered by rechargeable batteries. One limitation of UAVs with rechargeable batteries is that the batteries must be recharged at periodic intervals, which depend on the intensity of the tasks they perform. Currently, several methods exist for recharging a UAV's batteries, including physically removing the UAV from the undersea environment and transporting it to land, bringing the UAV aboard a ship for recharging, or lowering a charging port from a ship into the undersea environment. In other cases, the UAV can be returned to land and recharged by connecting to a platform, which may be solar-, motion-, or wind-powered. However, removing a UAV from its primary activity and transporting it to shore or recovering it at sea to recharge its batteries is inefficient. Furthermore, the ground operations required to recharge the UAV's batteries expose the UAV to unwanted surveillance and adverse weather conditions.

[0005] One or more charging stations are already deployed on the seabed, and UAVs can connect to these charging stations to recharge their batteries. Such charging stations are typically connected to undersea cables with power capacity, which is used to charge the UAV when connected to the station. Undersea cables typically have power capacity with a relatively high voltage but low current, so the time required to recharge the UAV's battery may be unavailable.

[0006] Therefore, more effective means of recharging UAVs and maintaining them in the undersea environment are desirable. Summary of the Invention

[0007] The present invention includes a docking / charging station, to which the UAV may be physically or wirelessly docked. The docking / charging station is provided with a battery or other power storage device that is gradually charged from a power conductor in a branch cable of the undersea communication system when the UAV is undocked from the docking / charging station. When the UAV docks in the docking / charging station, the battery on board the UAV may be rapidly charged by a battery on board the docking / charging station. The docking / charging station may be provided with data transmission and reception hardware, allowing the UAV to transmit data collected and stored during its task to / from the docking / charging station and then to a shore facility via the optical fiber in the branch cable. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram of an exemplary undersea communication system according to an embodiment of the present invention; [Figure 2] (A) is a schematic diagram of power diverted from the trunk cable to the branch cable, and (B) is the power in the trunk cable separated from the branch cable. [Figure 3] (A) is an optical fiber misaligned with a branch cable, and (B) is a schematic diagram of an optical fiber redirected from a trunk cable to a branch cable. [Figure 4] FIG. 1 is a block diagram of a power transmission section including a DC-DC conversion module (DDCM) for conditioning the power used by the subsea payload. [Figure 5] FIG. 5 is a block diagram of one possible implementation of the DDCM shown in FIG. 4. [Figure 6] FIG. 1 is a block diagram of a branching cable connected to a placement pallet on which a docking / charging station is mounted as one of multiple payloads. [Figure 7]FIG. 7 is a block diagram of the docking / charging station in FIG. 6 with a UAV docked thereto. DETAILED DESCRIPTION OF THE INVENTION

[0009] Submarine communication systems typically employ undersea cables consisting of one or more optical fiber cables, each cable having one or more optical fiber pairs and one or more power conductors. One embodiment of a submarine communication system 100 is shown in schematic form in FIG. 1. The communication system 100 may be a long-haul underwater system configured to carry optical channels from a transmitting terminal to a receiving terminal over cables of different lengths. The communication system 100 may include a trunk cable 102 that may be connected at each end of the cable to a land-based cable landing station (CLS) 110. Each cable landing station may include power feed equipment (PFE) 112 for providing power to the cable 102 and line terminating equipment (LTE) 114 for transmitting and receiving optical signals therebetween.

[0010] The communication system 100 transmits multiple optical channels over optical fibers housed within a cable 102. The system may be bidirectional, where each LTE 114 includes a receiver and a transmitter, and each optical fiber pair is used for bidirectional communication. The communication system 100 may transmit the communication channels over optical fibers using dense wavelength division multiplexing (DWDM). Submarine cables typically include at least one power conductor to provide power to multiple submarine repeaters 116 and various other components located between cable landing stations for amplifying the DWDM signals. The power conductor may be fed by a PFE 112 located on shore at each end of the cable. The PFE 112 typically provides power to the cable system at between 10 kV and 20 kV, although other voltages may be used. In some embodiments, the branch cable 104 may be a dual-conductor cable that can conduct power from the trunk line to connect to the trunk line, avoiding the need for an earth ground, as a single-conductor branch cable requires. One or more branch cables 104 can be connected to the trunk cable 102 at different locations. The branch cables 104 may be connected to the CLS 110 (not shown in FIG. 1) on shore or may be connected to a deployment pallet 120 on the seabed, as shown in FIG. 1. The branch cables 104 connected on the seabed can be used to transmit data to and from, and provide power to, various payloads 122A-122C connected to the deployment pallet 120. The payloads 122A-122C may be, for example, different types of sensor arrays.

[0011] The trunk cable 102 may include a switch branching unit (sBU) 106, which can switch both power and DWDM optical channels to the branch cable 104. FIG. 2A shows power from the trunk cable 102 being diverted to the branch cable 104 via conductor 202 and back to the trunk cable 102 via conductor 204. FIG. 2B shows the branch cable 104 in a de-energized bypass state, where power from the trunk cable 102 bypasses the branch cable 104 via a single conductor 206 in the trunk cable 102. By sending an optical signal to the sBU 106 over a command channel, the sBU 106 can be configured via LTE 114 from the shore. As shown in FIG. 3B, communication signals on the optical fiber in the trunk cable 102 can be diverted to the branch 104. FIG. 3A shows an optical fiber 302 bypassing the branch cable 104. 3 may only show signals in one optical fiber pair being diverted to branch cable 106, communication signals in multiple optical fiber pairs may be diverted pair by pair from trunk cable 102 to branch cable 104. In some embodiments, all wavelengths of light in the optical fiber may be transmitted to the branch cable, or various wavelengths of light may be dropped or added.

[0012] Returning to FIG. 1 , one or more deployment pallets 120 can be connected to the branch cable 104. The deployment pallet 120 serves as a base to which one or more payloads 122 can be connected. The payloads 122 may include, for example, various types of sensor arrays or other devices with commercial, research, or military applications. For example, payload 122A may include a seismometer for collecting seismic readings from the ocean floor. The deployment pallet 120 can transmit power from the branch cable 104 to the payloads 122. The deployment pallet 120 can also provide bidirectional communication with the payloads 122, allowing both collecting data collected by the payloads 122 and issuing commands to configure the payloads 122. The deployment pallet 120 may be equipped with multiple commercially available wet-mate connectors or other types of connectors, allowing one or more payloads 122 to be easily connected and disconnected from the deployment pallet 120. Wireless technology may be used for power and data connections. Alternatively, a single payload 122 can be directly connected to the branch cable 104 without the need for a deployment pallet 120.

[0013] Because the trunk cable 102 typically operates at 10 kV to 20 kV, the power delivered to the branch cable 104 can be regulated by a power transmission unit (PTU) 108. The PTU 108 may include a DC-DC converter module (DDCM) that can step the voltage from a high level at the trunk cable 102 to a low level required for the payloads 122 attached to the branch cable 104. In some embodiments, the PTU 108 can be controlled from shore by sending command signals via one or more side carrier or command bands in the optical fiber to control the level of voltage and / or current delivered to the payloads 122 attached to the branch cable 104. Thus, the PTU 108 isolates the payloads 122 from the high mains voltage. The PTU 108 may be controllable to provide constant current or constant voltage operation to the payloads 122 and may be configured to limit its output power to less than its full output power potential.

[0014] FIG. 4 is a block diagram of the PTU 108. The PTU 108 is coupled to the branch cable 104 downstream of the sBU 106. For purposes of illustration, assume that the branch cable 104 has two power conductors 408a and 408b. The trunk cable 102 can have a single power conductor or dual power conductors. The PTU 108 includes a power and telemetry section 402, which includes circuitry and components suitable for transmitting and receiving optical signals via an optical fiber 406 in the branch cable 104. In such a case, the sBU 106 must be configured to transmit the optical signal from the optical fiber in the trunk cable 102 to the optical fiber in the branch cable 104. The optical signal received by the power and telemetry section 402 is used to configure and adjust the operation of the DC-DC converter module (DDCM) 404 to use new operating parameters, such as the voltage setpoint and source mode (constant current, constant voltage). At 410, the regulated voltage is output from the PTU 108 to a downstream destination (eg, a placement pallet 120) for powering one or more payloads 122.

[0015] 5 shows a diagram of one possible implementation of the DDCM 404 adapted for use with the PTU 108. The DDCM 404 includes first, second, and third ports 408a, 408b, and 410, each configured to couple to a conductor of a cable segment. For example, the first port 408a may be configured to couple to a first conductor of the branch cable 104. The second port 408b may be configured to couple to a second conductor of the branch cable 104, and the third port 410 may be configured to couple to a downstream conductor of the branch cable 104. The DDCM 404 may be configured to extract current from one or two of the first and second ports 408a, 408b and provide power to the branch via the third port 410.

[0016] As further shown, the DDCM 404 includes a clamp circuit 502, first and second converters 504-1, 504-2, a controller 506, a rectifier 514, a filter 516, and a clamp circuit 508. The controller 506 may be powered via a power supply in the power and telemetry section 402 of the PTU 108. In some cases, the controller 506 may be implemented within the power and telemetry section 402 and is not necessarily a separate component as shown. The controller 506 may be implemented as a microprocessor, processor, circuit system, field programmable gate array (FPGA), or any other suitable controller device. The first and second converters 504-1, 504-2 may be configured to generate a regulated and controlled DC voltage and then chop the regulated and controlled DC voltage to generate an AC signal. While only first and second converters are shown in FIG. 5, it should be appreciated that multiple converters may be used. The AC can then be passed through a transformer for isolation and further rectified and filtered via rectifier 514 and filter 516, respectively, to produce a DC output. Multiple stages may be configured in the output section of the DDCM. For example, a clamp circuit 508 on the output can ensure the cable is discharged for operator safety. During a cable fault, a clamp circuit 502 on the input diverts (e.g., provides a path for) surge currents around the converter. Clamp circuits 502 may clamp to ground at each main cable to protect operators while repairing each main cable.

[0017] Thus, the first and second converters 504-1, 504-2 can provide two power stages. Each of the first and second converters 504-1, 504-2 may include a boost converter (not shown) and a chopper (not shown). For example, the first and second converters 504-1, 504-2 may be configured in a half-bridge (e.g., two-transistor) or full-bridge (e.g., four-transistor) switching arrangement. Each of the first and second converters 504-1, 504-2 may be operated in a current operating mode, for example, by soft switching (e.g., PWM signal) via the controller 506 to steer a portion of the line current from one or two of the first and second ports 408a, 408b. Other power regulation control forms are within the scope of the present invention, and the present invention is not necessarily limited to PWM embodiments. Also, a common transformer may be used with a flux load to add power at the output stage. In either case, the first and second converters 504-1, 504-2 can deliver boosted current to choppers, where each corresponding chopper drives a primary winding of an isolation transformer 530. The isolation transformer 530 can provide galvanic isolation between the first and second ports 408a, 408b and the third port 410.

[0018] Each of the boost converters of the first and second converters 504-1, 504-2 can be driven by a controller 506 via a first and second pulse-width modulation (PWM) signal, respectively, where the first PWM signal is different from the second PWM signal. The controller 506 can pump asymmetric loads from each of the first and second ports 408a, 408b based on the first and second PWM signals. Thus, the controller 506 can pump different amounts of power from the first and second ports 408a, 408b to achieve a desired output current / voltage. Depending on the desired configuration, each of the first and second converters 504-1, 504-2 can be configured to be the same or different. Regulation of the output (e.g., port 410) is relatively similar to regulation of a single-input converter, with the addition of a control scheme that ensures switching of the first and second converters 504-1, 504-2 to selectively extract current from each of the first and second ports 408a, 408b. Switching in this manner ensures that the first converter 504-1 is switched "on" and the second converter 504-2 is switched "off," and vice versa, preventing simultaneous input through the two ports. During the period when each of the converters 504-1, 504-2 is switched "on," current flows through the ports 408a, 408b. By controlling the proportion of time that the first converter 504-1 is switched on relative to the time that the second converter 504-2 is switched on during that period, the ratio of input currents can be controlled. In some embodiments, the ratio of input currents between the first and second ports 408a, 408b is not necessarily dependent on the total output load current; the duty cycle controls (e.g., first and second PWM signals) of the first and second converters 504-1, 504-2 may be scaled in this manner to time the two input currents, i.e., to maintain the ratio of inputs through the first and second ports 408a, 408b approximately constant. In some cases, the DDCM 404 may output a constant current or voltage in a cycle-by-cycle switching fashion or other cycle-by-cycle operating fashion. The described embodiments of the DDCM 404 should be considered exemplary.Other embodiments of DDCM 404 are possible within the contemplated scope of the present invention.

[0019] 6, one of the payloads 122 may be a docking / charging station 602 for a UAV 750, which is shown in schematic form docking to the docking / charging station 602 in FIG. 7. The UAV 750 typically includes a battery 752 for powering the UAV 750 and for supplying electrical power to onboard circuit systems for navigation and control of tasks performed by the UAV 750. The UAV 750 may further include a data store 754, which contains data collected when the UAV 750 leaves the docking / charging station 602.

[0020] 7 , the docking / charging station 602 can be connected to the placement pallet 120 and can be provided with a battery 704 that can be gradually charged when the UAV 750 undocks from the docking / charging station 602. Because the branch cable 104 has a finite capacity to deliver power, the battery 704 can be gradually charged over time when the UAV 750 is undocked. When the UAV 750 docks at the docking / charging station 602, the battery 752 in the UAV 750 can be rapidly charged from the battery 704 in the docking / charging station 602.

[0021] The docking / charging station 602 may also include a data exchange module 706 for transmitting data collected by the UAV 750 and stored in a data store 754 via a cable included in the branch cable 104. Additionally, when the UAV 750 is mated with the docking / charging station 602 for charging, data and new task instructions may be transmitted from the docking / charging station 602 to the UAV 750. In some embodiments, the positioning pallet 120 is optional, and the branch cable 104 may connect directly to the docking / charging station 602.

[0022] In addition to the components shown in FIG. 7 , the docking / charging station 602 may further include hardware that enables the UAV 750 to mate (dock) with the docking / charging station 602. Note that the UAV 750 may be “mated” with the docking / charging station 602 by physically docking or by establishing one or more physical data and power connections between the UAV 750 and the docking / charging station 602 in other ways. In other embodiments, the term “mating” may be interpreted to mean that data and / or power is exchanged wirelessly between the UAV 750 and the docking / charging station 602. The docking / charging station 602 may also include hardware that functions as a beacon or transmitter to allow the UAV 750 to easily locate and / or identify the docking / charging station 602. In other embodiments, the data connection between the UAV 750 and the docking / charging station 602 may be bidirectional, such that commands or programs can be sent to the UAV 750 via the branching cable 104.

[0023] Various examples have been generally described above, and those skilled in the art will appreciate that actual embodiments of the invention may deviate from the examples described while remaining within the scope of the invention as set forth in the following claims.

Claims

1. Housing and a connection to a submarine cable comprising both power conductors and optical fibers for data transmission; a battery provided within the housing, receiving power from a land power source via the power conductor of the submarine cable and supplying the power to the submarine autonomous navigation vehicle; a data exchange module for bidirectionally exchanging data with the submarine autonomous navigation vehicle and the land base station via a docking / charging module and the optical fiber of the submarine cable; a transmitter provided in the housing and configured to emit a signal so that the undersea autonomous vehicle can locate the position of the docking / charging module; Equipped with Docking and charging module for undersea autonomous vehicles.

2. The connection mechanism is a power connection to the power conductor; a data connection to said optical fiber. The docking and charging module of claim 1 .

3. the docking / charging module is configured to physically mate with the undersea autonomous vehicle; The docking and charging module of claim 2 .

4. and a connection between the docking / charging module and the undersea autonomous vehicle for bidirectional data exchange therebetween. The docking and charging module of claim 3 .

5. the power connection and the data connection to the submarine cable are via a location pallet to provide power and data linkage between the submarine cable and the docking / charging module; The docking and charging module of claim 2 .

6. The data exchange module a function of receiving data collected by the undersea autonomous navigation vehicle and transmitting the data to the land base station via the undersea cable; and transmitting data from the land-based base station to the undersea autonomous vehicle. A docking and charging module according to any one of claims 1 to 5.

7. Navigating the submarine autonomous navigation vehicle to the submarine docking / charging module based on a beacon signal transmitted from the submarine docking / charging module so that the submarine autonomous navigation vehicle can locate the submarine docking / charging module; docking the undersea autonomous vehicle to the subsea docking / charging module, the docking including establishing a physical connection for transmitting power from the subsea docking / charging module to the subsea autonomous vehicle; transferring power from a charged battery in the subsea docking / charging module to a battery in the subsea autonomous vehicle; and disconnecting the physical connection. the submarine docking and charging module is connected to a submarine cable; the submarine cable provides both power and data connections to land-based base stations; A method for providing rapid charging to an undersea autonomous vehicle.

8. transmitting data from a data store on the undersea autonomous vehicle to the undersea docking and charging module; transmitting the data from the submarine docking / charging module to the land-based base station or to another device in communication with the docking / charging module via the submarine cable. The method of claim 7.

9. transmitting data from the land-based base station to the submarine docking and charging module via the submarine cable; transmitting the data from the subsea docking / charging module to a data store on the subsea autonomous vehicle. The method of claim 8.

10. and charging the battery in the subsea docking / charging module via the power connection in the subsea cable when the subsea autonomous vehicle is detached from the subsea docking / charging module.

10. The method according to any one of claims 7 to 9.

11. A housing; a submarine cable including a power conductor for power transmission and an optical fiber for data transmission, and a connection mechanism configured to connect to the power transmission section disposed between the docking / charging module; a battery provided within the housing, receiving power from a land power source via the power conductor of the submarine cable and supplying the power to the submarine autonomous navigation vehicle; a data exchange module for bidirectionally exchanging data with the submarine autonomous navigation vehicle and the land base station via the docking / charging module and the optical fiber of the submarine cable; Equipped with Docking and charging module for undersea autonomous vehicles.

12. The power transmission unit provides a constant current or a constant voltage to the docking / charging module via the connection mechanism.

12. The docking and charging module of claim 11.

13. The power transmission unit includes a DC-DC converter module, and the DC-DC converter module adjusts and controls the power supplied to the docking / charging module.

12. The docking and charging module of claim 11.

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