Square-rig wing sail for unmanned surface vehicles

Abstract

Techniques are provided for an unmanned surface vehicle including a vehicle body and a rigid square-rig wing coupled with the primary vehicle body. The rigid square-rig wing includes a first surface configured to interact with wind to generate a force that propels the primary vehicle body in a direction of travel that is primarily composed of drag, and a second surface configured to interact with the wind to generate a force that propels the primary vehicle body in a direction of travel that is primarily composed of lift. The unmanned surface vehicle further includes a rudder and a control system comprising a controller, the control system configured to determine a rudder position and generate a signal to position the rudder to the rudder position.

What is claimed is: 
     
         1 . An unmanned surface vehicle comprising:
 a vehicle body;   a rigid wing rotationally coupled with the vehicle body such that the rigid wing has a limited range of rotational movement with respect to the vehicle body, the limited range of rotational movement allowing the unmanned surface vehicle to sail a limited arc with respect to the wind, the rigid wing comprising:
 a first surface positioned to face a rear end of the vehicle body in all positions of the limited range of rotational movement, the first surface configured to interact with wind to generate a force that propels the vehicle body that is primarily composed of drag, and 
 a second surface positioned to face a front end of the vehicle body in all positions of the limited range of rotational movement, the second surface configured to interact with wind to generate a force that propels the vehicle body that is primarily composed of lift; 
   a rudder;   a control system comprising a controller, the control system configured to determine a rudder position and generate a signal to position the rudder to the rudder position.   
     
     
         2 . The unmanned surface vehicle of  claim 1 , wherein the limited range of rotational movement is about 45° in each direction. 
     
     
         3 . The unmanned surface vehicle of  claim 1 , wherein the limited arc is about 270°. 
     
     
         4 . The unmanned surface vehicle of  claim 1 , wherein the limited arc is about 300°. 
     
     
         5 . The unmanned surface vehicle of  claim 1 , wherein the control system is configured to determine a wing angle within the limited range of rotational movement and generate a signal to position the rigid wing to the wing angle. 
     
     
         6 . The unmanned surface vehicle of  claim 1 ,
 wherein, in a first rudder position that directs the unmanned surface vehicle in a downwind direction, the force generated on the rigid wing is primarily a drag component generated by the interaction of apparent wind with the first surface;   wherein, in a second rudder position that directs the unmanned surface vehicle in a perpendicular direction with respect to apparent wind, the force generated on the rigid wing is primarily a lift component generated by the interaction of apparent wind with the second surface.   
     
     
         7 . The unmanned surface vehicle of  claim 1 , wherein the rigid wing is substantially symmetric with respect to starboard tack and port tack. 
     
     
         8 . The unmanned surface vehicle of  claim 1 , further comprising a water generator coupled to the vehicle body, the water generator configured to generate energy when the unmanned surface vehicle travels forward. 
     
     
         9 . The unmanned surface vehicle of  claim 8 , wherein the energy generated by the water generator powers one or more systems of the unmanned surface vehicle during extended periods of darkness. 
     
     
         10 . The unmanned surface vehicle of  claim 1 , further comprising one or more solar panels coupled with the rigid wing. 
     
     
         11 . The unmanned surface vehicle of  claim 1 , wherein a windward surface of the rigid wing is flat. 
     
     
         12 . The unmanned surface vehicle of  claim 1 , wherein a windward surface of the rigid wing is concave. 
     
     
         13 . The unmanned surface vehicle of  claim 1 , further comprising a keel coupled with the vehicle body at a first end of the keel, wherein the keel comprises ballast sufficient to provide a positive righting moment sufficient to cause the vehicle body to passively right from any position. 
     
     
         14 . The unmanned surface vehicle of  claim 1 , wherein the rigid wing comprises at least one positively buoyant sealed compartment, wherein the sealed compartment provides a positive righting moment when the rigid wing is submerged. 
     
     
         15 . The unmanned surface vehicle of  claim 1 , further comprising a wireless communication device comprising an antenna, wherein the controller is further configured to obtain at least one waypoint location from the wireless communication device. 
     
     
         16 . The unmanned surface vehicle of  claim 15 , wherein the wireless communication device is further configured to transmit data generated by the controller based on at least one device coupled with the controller. 
     
     
         17 . The unmanned surface vehicle of  claim 1 , wherein the controller is further configured to periodically determine an updated rudder position and generate a signal to position the rudder to the updated rudder position. 
     
     
         18 . The unmanned surface vehicle of  claim 1 , wherein the vehicle body comprises a narrow front end with reduced buoyancy. 
     
     
         19 . The unmanned surface vehicle of  claim 1 , further comprising at least one power source coupled with the control system, wherein the at least one power source comprises at least one battery.