System and method for retrieving daughterboats to a mothership

Abstract

A system for retrieving manned or unmanned daughter boats onto a mothership. The mothership has a crane/davit, a lifting wire connected to a winch, a first connecting device and a drone assembly including propellers and motors. The daughter boat has a second connecting device for cooperation with the first connection device. The drone assembly is removably fastened to the lifting wire and is provided to move the lifting wire and the first connection part in a horizontal plane to a required position above the second connection part. The winch of the mothership might be connected to a winch control system in order to keep the first connection part in a required vertical position for connection to the second connection part.

1 . A system for retrieving manned or unmanned daughter boats onto a mothership, where the mothership has a crane/davit, a lifting wire connected to a winch, a first connecting device and a drone assembly comprising propellers and motors, and the daughter boat has a second connecting device for cooperation with the first connection device, wherein the drone assembly is removably fastened to the lifting wire and is provided to move the lifting wire and the first connection part in a horizontal plane to a required position above the second connection part, and the winch of the mothership might be connected to a winch control system in order to keep the first connection part in a required vertical position for connection to the second connection part. 
     
     
         2 . The system according to  claim 1 , wherein the drone assembly comprises one or more sensors which can read a marking at or in the vicinity of the second connection part, said sensor(s) communicate(s) with a drone controller regulating the horizontal position of the drone assembly in response to information from the sensor and position the first connection part in the required position above the second connection part for connection of the two connection part. 
     
     
         3 . The system according to  claim 1 , wherein the sensor or sensors is/are one or more cameras which are able to locate the marking on the daughter boat. 
     
     
         4 . The system according to  claim 1 , wherein the marking on the daughter boat is/are a sensor-readable QR-marking, an Aruco code marker, an April Tag or similar. 
     
     
         5 . The system according to  claim 1 , wherein the marking on the daughter boat is/are a sound producing device. 
     
     
         6 . The system according to  claim 1 , wherein the winch control system and the drone controller are interconnected and can operate the system in an automatic mode. 
     
     
         7 . The system according to  claim 1 , wherein the movement of the drone assembly in the horizontal plane controlled by the drone controller, is obtained by either 1) reversing rotational direction of the drone motors and reversing the thrust of the propellers or 2) by moving the direction of the propellers, for example by means of servo motors and turn the thrust of the propellers in another direction, or 3) having 4 (or 8) separate motors and propellers mounted in a fixed arrangement, whereby they provide thrust in each horizontal direction. 
     
     
         8 . The system according to  claim 1 , wherein the daughter boat to be retrieved, is a submerged vehicle and the drone assembly is an underwater drone assembly. 
     
     
         9 . The system according to  claim 1 , where the second connection part comprises a funnels and a female connection part, whereas to minimize the dimensions of the installation in the daughter boat while still being able to connect in harsh weather, the funnel is designed to fold/collapse away when not needed and to extend/fold into shape before connection. 
     
     
         10 . The system according to  claim 1 , whereas to extend the window of operation, the winch uses an active heave compensation mode to keep the vertical distance to the daughter boat. 
     
     
         11 . The system according to  claim 1 , whereas the second connection part is mounted on the lifting wire and the first connection part is mounted in the daughter boat, allowing the second connector part being integrated in the spelter-socket and reducing the overall dimension of the installation. 
     
     
         12 . The system according to  claim 1 , whereas to increase the window of operation, the drone part includes a dynamically extending part that is able to extend faster than the winch can lower, and catch the counter part on the USV, and thus create a guide between the drone/wire and the USV.