System and method for recovery of autonomous underwater vehicles

Abstract

An autonomous tethered vehicle for recovering autonomous underwater vehicles (AUVs) is provided. The autonomous tethered vehicle includes an open-structure frame with vertical and horizontal frame members and a top surface attached to a top portion of the open-structure frame. The autonomous tethered vehicle further includes at least four horizontal thrusters operable to provide lateral maneuvering and at least two vertical thrusters operable to provide vertical thrust. Additionally, the autonomous tethered vehicle includes a plurality of onboard sensors operable to provide positional information of the autonomous tethered vehicle in reference to a nearby AUV, and an electronics housing unit having a control system operable to collect data from the plurality of the onboard sensors and make real-time operational decisions based on the collected data.

What is claimed is: 
     
         1 . A tethered vehicle for recovering autonomous underwater vehicles, comprising:
 an open-structure frame comprising vertical and horizontal frame members;
 a top surface attached to a top portion of the open-structure frame; 
 at least four horizontal thruster, each positioned on a respective vertical frame member of the open-structure frame, the four horizontal thrusters operable to provide lateral maneuvering to the tethered vehicle; 
 at least two vertical thruster integrated into the top surface and operable to provide vertical thrust to the tethered vehicle; 
 a plurality of onboard sensors attached to the open-structure frame, the plurality of onboard sensor operable to provide positional information of the tethered vehicle in reference to a nearby autonomous underwater vehicle (AUV); and 
 an electronics housing unit attached to the open-structure frame, the electronics housing unit comprising a control system operable to collect data from the plurality of the onboard sensors and make real-time operational decisions for the tethered vehicle based on the collected data. 
   
     
     
         2 . The tethered vehicle of  claim 1 , wherein the control system allows the tethered vehicle to seek and attach to the AUV autonomously or with limited human intervention. 
     
     
         3 . The tethered vehicle of  claim 1 , wherein the open-structure frame is made from a lightweight material. 
     
     
         4 . The tethered vehicle of  claim 1 , wherein the plurality of onboard sensors comprises acoustic sensors operable to receive acoustic signals emitted from the AUV. 
     
     
         5 . The tethered vehicle of  claim 1 , wherein the plurality of onboard sensors comprises four cameras operable to optically identify fiducial targets on the AUV. 
     
     
         6 . The tethered vehicle of  claim 1 , further comprising an actuator positioned on the top surface ( 208 ) of the tethered vehicle operable to enable vertical movement of the tethered vehicle along a length of a crane cable traversing the top surface of the tethered vehicle. 
     
     
         7 . The tethered vehicle of  claim 6 , wherein the crane cable comprises a docking mechanism configured to mechanically latch on a corresponding receptacle on the AUV to mechanically couple the tethered vehicle to the AUV. 
     
     
         8 . The tethered vehicle of  claim 7 , wherein the vertical position of the docking mechanism relative to the AUV is controlled with a hard stop attached to the crane cable above the actuator. 
     
     
         9 . The tethered vehicle of  claim 6 , wherein the crane cable is a multi-functional conduit configured to facilitate both mechanical deployment and data connectivity between the tethered vehicle and a recovery vessel. 
     
     
         10 . The tethered vehicle of  claim 9 , wherein the electronics housing unit is communicatively coupled to the crane cable so that the control system becomes communicatively coupled to the recovery vessel. 
     
     
         11 . A method for recovering autonomous underwater vehicles, comprising:
 instructing an autonomous underwater vehicle (AUV) to approach a recovery vessel at a predetermine underwater location;   deploying an autonomous tethered vehicle from a deck of the recovery vessel at the predetermined underwater location, the autonomous tethered vehicle being tethered to the recovery vessel via a crane cable;   upon deployment of the autonomous tethered vehicle from the deck of the recovery vessel, allowing the recovery vessel to enter a drift mode to minimize its relative motion to the autonomous tethered vehicle;   the autonomous tethered vehicle, using a first set of sensors attached to an open-structure frame of the autonomous tethered vehicle, detecting the AUV and navigating towards the AUV to position itself over the AUV;   the autonomous tethered vehicle, using a second set of sensors attached to the open-structure frame of the autonomous tethered vehicle, detecting fiducial targets on the AUV and subsequently using the fiducial targets as alignment marks to align to the AUV; and   upon alignment with the AUV, the autonomous tethered vehicle deploying a docking mechanism attached to an end of the crane cable towards a receptacle on the AUV to dock the AUV.   
     
     
         12 . The method of  claim 11 , further comprises:
 lifting the autonomous tethered vehicle and the docked AUV from sea level to the deck of the recovery vessel; and   upon lowering the autonomous tethered vehicle and the docked AUV to the deck of the recovery vessel, aligning the docked AUV to a capture frame on the deck.   
     
     
         13 . The method of  claim 11 , wherein deploying the autonomous tethered vehicle from the deck of the recovery vessel comprises:
 attaching the autonomous tethered vehicle to a crane via the crane cable;   with the crane lifting the autonomous tethered vehicle from the deck of the recovery vessel and positioning the autonomous tethered vehicle over sea water; and   lowering the autonomous tethered vehicle to sea level above the predetermined underwater location.   
     
     
         14 . The method of  claim 11 , wherein using the first set of sensors attached to the open-structure frame of the autonomous tethered vehicle comprises using acoustic sensors operable to receive acoustic signals emitted from the AUV. 
     
     
         15 . The method of  claim 11 , wherein using the second set of sensors attached to the open-structure frame of the autonomous tethered vehicle comprises using optical sensors. 
     
     
         16 . The method of  claim 15 , wherein the optical sensors comprise digital cameras. 
     
     
         17 . The method of  claim 11 , wherein deploying the docking mechanism comprises using an actuator attached to a top surface of the autonomous tethered vehicle above the open-structure frame, the actuator operable to enable vertical movement of the autonomous tethered vehicle along a length of the crane cable. 
     
     
         18 . The method of  claim 17 , wherein a vertical position of the docking mechanism relative the AUV is controlled with a hard stop attached to the crane cable above the actuator. 
     
     
         19 . The method of  claim 1 , wherein the autonomous tethered vehicle while navigating towards the AUV and deploying the docking mechanism uses horizontal and vertical thrusters controlled by an onboard control system to maintain alignment with the AUV under high-current underwater conditions. 
     
     
         20 . The tethered vehicle of  claim 1 , wherein the crane cable is a multi-functional conduit configured to facilitate mechanical deployment and data connectivity between the autonomous tethered vehicle and the recovery vessel.