GPS airborne target geolocating method

Abstract

A geolocation method is applied for accurate targeting of a target using an airborne beacon as a pseudo star generated by a high altitude vehicle, and using optical sensors by a low altitude vehicle for imaging the beacon and target for generating accurate relative GPS positioning of the target for improved the geolocation of the target preferably for precise delivery of a payload to the target. The method is applicable to military and civilian needs for accurate delivery of a payload to a target, such as for precise delivery of humanitarian aid or weapon munitions.

1. A method for determining a target location of a target, the method comprising the steps of,
 sensor determining a first GPS position of a sensor platform, the first GPS position having GPS positioning errors,  
 beacon determining a second GPS position of a beacon platform, the second GPS position having GPS positioning errors, the first and second GPS positions having relative errors less than the GPS positioning errors,  
 beacon measuring a beacon offset angle,  
 target measuring a target offset angle, and  
 computing the target location of the target from the first and second GPS positions and the beacon offset angle and the target offset angle.  
 
     
     
       2. The method of  claim 1  further comprising the steps of,
 determining a third GPS position of a maneuvering payload,  
 communicating the target location of the target to the maneuvering payload, and  
 maneuvering payload toward the target location.  
 
     
     
       3. The method of  claim 1  further comprising the steps of,
 determining a third GPS position of a maneuvering payload,  
 communicating the target location of the target to the maneuvering payload,  
 maneuvering payload toward the target location, and  
 repeating all of the steps for repetitively communicating the target location of the target to the maneuvering payload while the maneuvering payload maneuvers along a payload track towards the target.  
 
     
     
       4. The method of  claim 1  wherein,
 the first GPS position has a y 1  altitude and an x 1  and a z 1  horizontal position, the second GPS position has a y 2  altitude and an x 2  and a z 2  horizontal position,  
 the beacon offset angle comprises the angle of φ x  and φ z ,  
 the target offset angle comprises the angles of θ x  and θ z , and  
 the target location is a horizontal location at x 3  and z 3 .  
 
     
     
       5. The method of  claim 1  wherein,
 the first GPS position has a Y 1  altitude and an x 1  horizontal position, the second GPS position has a Y 2  altitude and an x 2  horizontal position,  
 the beacon offset angle comprises the angle of φ x ,  
 the target offset angle comprises the angles of θ x , and  
 the target location is a horizontal location at x 3 , where x 3 =y 1  tanθ x +φ x −α x   where α x =arctan(x 2 /(y 2 −y 1 )).  
 
     
     
       6. The method of  claim 1  wherein the beacon measuring step comprises the step of,
 calibrating a focal plane of a beacon sensor of the sensor platform for measuring the beacon offset angle.  
 
     
     
       7. The method of  claim 1  wherein the target measuring step comprises the step of,
 calibrating a focal plane of a target sensor of the sensor platform for measuring the target offset angle.  
 
     
     
       8. The method of  claim 1  wherein,
 the beacon measuring step comprises the step of calibrating a beacon focal plane of a beacon sensor of the sensor platform for measuring the beacon offset angle,  
 the target measuring step comprises the step of calibrating a target focal plane of a target sensor of the sensor platform for measuring the target offset angle, and  
 the calibrating of the beacon and target focal plane is relative to respective fields of view of a common boresight.  
 
     
     
       9. A method for delivering a payload to a target location of a target, the method comprising the steps of,
 determining a first GPS position of a sensor platform,  
 determining a second GPS position of a beacon platform, the first and second GPS positions having relative errors,  
 measuring a beacon offset angle,  
 measuring a target offset angle,  
 computing the target location of the target from the first and second GPS position and beacon offset angle and target offset angle,  
 determining a third GPS position of a maneuvering payload,  
 communicating the target location to the maneuvering payload, and  
 maneuvering payload toward to the target location for delivering the payload to the target location.  
 
     
     
       10. The method of  claim 9  wherein maneuvering payload is a smart bomb comprising GPS navigation, guide communications, and a munitions payload. 
     
     
       11. A method for determining a target location of a target, comprising:
   determining a first GPS position of a sensor platform;        determining a second GPS position of a beacon platform;        determining a beacon offset angle;        determining a target offset angle; and        determining the target location from at least the first and second GPS positions and the beacon offset angle and the target offset angle.     
     
     
       12. The method of  claim 11 , further comprising:
   determining a third GPS position of a maneuvering payload; and        communicating the target location to the maneuvering payload.     
     
     
       13. The method of  claim 12 , further comprising guiding the maneuvering payload toward the target location. 
     
     
       14. The method of  claim 12 , further comprising repetitively communicating the target location to the maneuvering payload while the maneuvering payload maneuvers along a payload track towards the target. 
     
     
       15. The method of  claim 11 , wherein
   the first GPS position has a y   1    altitude and an x   1    and a z   1    horizontal position, the second GPS position has a y   2    altitude and an x   2    and a z   2    horizontal position;        the beacon offset angle comprises the angle of φ   x    and φ   z   ;        the target offset angle comprises the angles of θ   x    and θ   z   ; and        the target location is a horizontal location at x   3    and z   3   .     
     
     
       16. The method of  claim 11  wherein,
   the first GPS position has a y   1    altitude and an x   1    horizontal position, the second GPS position has a y   2    altitude and an x   2    horizontal position;        the beacon offset angle comprises the angle of φ   x   ;        the target offset angle comprises the angle of θ   x   ; and        the target location is a horizontal location at x   3   , where x   3   =y   1  tan[θ x   +φ   x   −α   x   ] where α   x   =arctan ( x   2 /( y   2   −y   1 )).   
     
     
       17. The method of  claim 11 , wherein said determining of the beacon offset angle comprises calibrating a focal plane of a beacon sensor of the sensor platform for measuring the beacon offset angle. 
     
     
       18. The method of  claim 11 , wherein said determining of the target offset angle comprises calibrating a focal plane of a target sensor of the sensor platform for measuring the target offset angle. 
     
     
       19. The method of  claim 11 , wherein
   said determining of the beacon offset angle comprises calibrating a beacon focal plane of the beacon sensor of the sensor platform for measuring the beacon offset angle,        said determining of the target offset angle comprises calibrating a target focal plane of the target sensor of the sensor platform for measuring the target offset angle, and        said calibrating of the beacon and target focal plane is relative to respective fields of view of a common boresight reference.     
     
     
       20. The method of  claim 11 , further comprising relating the target location to a three dimensional map to determine an altitude of the target. 
     
     
       21. A method for delivering a payload to a target comprising:
   determining a first GPS position of a sensor platform;        determining a second GPS position of a beacon platform;        determining a beacon offset angle;        determining a target offset angle;        computing a location of the target from at least the first and second GPS position and beacon offset angle and target offset angle;        determining a third GPS position of a maneuvering payload;        communicating the location of the target to the maneuvering payload; and        maneuvering the payload toward the location of the target.     
     
     
       22. The method of  claim 21 , wherein the maneuvering payload comprises a smart bomb. 
     
     
       23. The method of  claim 22 , wherein the smart bomb comprises GPS navigation, guide communications, and a munitions payload. 
     
     
       24. The method of  claim 21 , wherein the maneuvering payload comprises a humanitarian payload. 
     
     
       25. A computer readable medium comprising computer executable instructions that when executed by a computer system, perform the method of:
   determining a first GPS position of a sensor platform;        determining a second GPS position of a beacon platform;        determining a beacon offset angle;        determining a target offset angle; and        computing a location of the target from at least the first and second GPS positions and the beacon offset angle and the target offset angle.     
     
     
       26. A computer programmed by software so as to perform the method of:
   determining a first GPS position of a sensor platform;        determining a second GPS position of a beacon platform;        determining a beacon offset angle;        determining a target offset angle; and        computing a location of the target from at least the first and second GPS positions and the beacon offset angle and the target offset angle.