SHORT BASELINE HELICOPTER POSITIONING RADAR FOR LOW VISIBILITY

• US 20100328138A1
• Filed: 04/28/2010
• Published: 12/30/2010
• Est. Priority Date: 05/07/2009
• Status: Active Grant

• Current Assignee: Intelligent Sciences, Ltd.
• Original Assignee: Intelligent Sciences, Ltd.
• Inventors: GUIGNÉ, Jacques Y., STACEY, James A., PACE, Nicholas G.
• Granted Patent: US 8,354,951 B2
• Time in Patent Office: Days
• US Class Current: 342/33
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 13/913 for landing purposes

Abstract

A method for determining position and orientation of a rotating wing aircraft (e.g. helicopter) with respect to a ground station includes transmitting an electromagnetic signal from the aircraft. The signal includes a plurality of electromagnetic signals, each signal having a different selected frequency. The signal is detected at an array of sensors disposed on the ground surface in a selected pattern. The array includes at least one reference sensor and at least three spaced apart time difference determination sensors. A difference in arrival time of the signals between the reference sensor and each of the time difference determination sensors is determined and a spatial position of the aircraft is determined from the time differences.

Claims

1. A method for determining position of an aircraft with respect to a ground station, comprising:

transmitting a signal from the aircraft, the signal comprising a plurality of electromagnetic signals, each signal having a different selected frequency;

detecting the signals at an array of sensors disposed on the ground surface in a selected pattern, the array including at least one reference sensor and at least three spaced apart time difference determination sensors;

determining a difference in arrival time of the signals between the reference sensor and each of the time difference determination sensors; and

determining a spatial position of the aircraft from the time differences.

2. The method of claim 1 wherein the time differences are determined by determining a relationship between a frequency of the signal and a phase difference between signals detected by each of the sensors.

3. The method of claim 1 wherein the time difference determination sensors are disposed on a circle having a selected radius from a position of the reference sensor.

4. The method of claim 1 wherein more than four difference determination sensors are used, and such sensors are arranged in a regular, irregular or random array geometry.

5. The method of claim 1 wherein the selected radius is such that the phase difference does not exceed the value 2π

when the aircraft is within a predetermined distance from the array.

6. The method of claim 1 further comprising deploying the array of sensors from the aircraft prior to landing thereof.

7. The method of claim 1 further comprising measuring an altitude of the aircraft at a plurality of spaced apart positions and a geodetic orientation of the aircraft thereof, and calibrating an altitude determined from the spatial position using the measured altitudes.

8. A method for determining position of an aircraft with respect to a ground station, comprising:

transmitting a signal from the ground station, the signal comprising a plurality of electromagnetic signals, each signal having a different selected frequency;

detecting the signals at an array of sensors disposed on the aircraft in a selected pattern, the array including at least one reference sensor and at least three spaced apart time difference determination sensors;

determining a difference in arrival time of the signals between the reference sensor and each of the time difference determination sensors; and

determining a spatial position of the aircraft from the time differences.

9. The method of claim 8 wherein the time differences are determined by determining a relationship between a frequency of the signal and a phase difference between signals detected by each of the sensors.

10. The method of claim 8 wherein the time difference determination sensors are disposed on a circle having a selected radius from a position of the reference sensor.

11. The method of claim 8 wherein the selected radius is such that the phase difference does not exceed the value 2π

when the aircraft is within a predetermined distance from the array.

12. The method of claim 8 further comprising measuring an altitude of the aircraft at a plurality of spaced apart positions and a geodetic direction thereof, and calibrating an altitude determined from the spatial position using the measured altitudes.