Determining aircraft position and attitude using GPS position data

• US 6,345,232 B1
• Filed: 04/27/1999
• Issued: 02/05/2002
• Est. Priority Date: 04/10/1997
• Status: Expired due to Fees

• Current Assignee: Robert C. Ettinger, Urban H.D. Lynch
• Original Assignee: Robert C. Ettinger, Urban H.D. Lynch
• Inventors: Ettinger, Robert C., Lynch, Urban H. D.
• Primary Examiner(s): Zanelli, Michael J.
• Application Number:
  US09/300,635
• Time in Patent Office: 1,015 Days
• Field of Search: 701/213, 701/214, 701/14, 342/357.06, 342/357.12
• US Class Current: 701/214
• CPC Class Codes: G01S 19/15 Aircraft landing systems
• CPC Class Codes: G01S 19/39 the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
• CPC Class Codes: G01S 19/42 Determining position
• CPC Class Codes: G01S 19/53 Determining attitude

Abstract

The present invention is a method and apparatus to determine flight parameters of an aircraft. Data received from a global positioning system (GPS) receiver are converted to position data. The position data are filtered based on a least-squares fitting to generate smoothed position data which provide the flight parameters.

Claims

1. A method comprising:

converting data received from a global positioning system (GPS) receiver to position data; and

filtering the position data based on a least-squares fitting to generate smoothed position data, the filtering comprising;

interpolating the position data to provide interpolated data, and

smoothing the position and the interpolated data to provide the smoothed position data.

2. The method of claim 1 further comprising

converting the smoothed position data to flight parameters of an aircraft.

3. The method of claim 2 wherein the flight parameters include at least one of yaw, pitch, and roll angles.

4. The method of claim 2 wherein the flight parameters include at least one of velocity and acceleration.

5. The method of claim 1 wherein smoothing comprises:

smoothing the position and interpolated data in a first time interval window to produce a first smoothed data set; and

smoothing the first smoothed data set in a second time interval window to produce a second smoothed data set, the second data set corresponding to the smoothed position data.

6. The method of claim 5 wherein the first and second time interval windows have same length.

7. The method of claim 6 wherein the second time interval window is shifted in time with respect to the first time interval window by a shift amount.

8. The method of claim 1 wherein interpolating comprises:

interpolating the position data using a linear interpolation.

9. The method of claim 1 wherein the least-squares fitting is a second order curve fitting.

10. A computer program product comprising:

a computer usable medium having computer program code embodied therein to determine flight parameters of an aircraft, the computer program product having;

(a) computer readable program code for converting data received from a global positioning system (GPS) receiver to position data; and

(b) computer readable program code for filtering the position data based on a least-squares fitting to generate smoothed position data, comprising;

(b1) computer readable program code for interpolating the position data to provide interpolated data, and

(b2) computer readable program code for smoothing the position and the interpolated data to provide the smoothed position data.

11. The computer program product of claim 10 further comprising

(a) computer readable program code for converting the smoothed position data to the flight parameters of an aircraft.

12. The computer program product of claim 11 wherein the flight parameters include at least one of yaw, pitch, and roll angles.

13. The program product of claim 11 wherein the flight parameters include at least one of velocity and acceleration.

14. The computer program product of claim 11 wherein the computer readable program code for smoothing comprises:

(b21) computer readable program code for smoothing the position and interpolated data in a first time interval window to produce a first smoothed data set; and

(b22) computer readable program code for smoothing the first data set in a second time interval window to produce a second smoothed data set, the second data set corresponding to the smoothed position data.

15. The computer program product of claim 14 wherein the first and second time interval windows have same length.

16. The computer program product of claim 15 wherein the second time interval window is shifted in time with respect to the first time interval window by a shift amount.

17. The computer program product of claim 10 wherein the computer readable program code for interpolating comprises:

(b11) computer readable program code for interpolating the position data using a linear interpolation.

18. The computer program product of claim 10 wherein the least-squares fitting is a second order curve fitting.

19. A system comprising:

a global positioning system (GPS) data recording unit to record GPS data corresponding to position of an aircraft;

a processor coupled to the GPS data recording unit to determine flight parameters of the aircraft; and

a memory coupled to the processor to store instructions executable by the processor, the instructions when executed by the processing unit causing the processor to;

convert data received from a global positioning system (GPS) receiver to position data, and

filter the position data based on a least-squares fitting to generate smoothed position data, the instructions causing the processor to filter the position data causes the processor to;

interpolate the position data to provide interpolated data, and

smooth the position and the interpolated data to provide the smoothed position data.

20. The system of claim 19 wherein the memory further comprising instructions, when executed by the processor, causing the processor to:

convert the smoothed position data to the flight parameters.

21. The system of claim 20 wherein the flight parameters include at least one of yaw, pitch, and roll angles.

22. The system of claim 20 wherein the flight parameters include at least one of velocity and acceleration.

23. The system of claim 19 wherein the instructions, when executed, causing the processor to smooth the position and the interpolated data causes the processor to:

smooth the position and interpolated data in a first time interval window to produce a first smoothed data set; and

smooth the first data set in a second time interval window to produce a second smoothed data set, the second data set corresponding to the smoothed position data.

24. The system of claim 23 wherein the first and second time interval windows have same length.

25. The system of claim 24 wherein the second time interval window is shifted in time with respect to the first time interval window by a shift amount.

26. The system of claim 19 wherein the processor interpolates the position data using a linear interpolation.

27. The system of claim 19 wherein the least-squares fitting is a second order curve fitting.

28. A method comprising:

filtering position data of an aircraft based on least-squares fitting to generate smoothed position data, the position data being provided by a GPS receiver, the filtering comprising;

interpolating the position data to provide interpolated data, and

smoothing the position and the interpolated data to provide the smoothed position data; and

determining attitude of the aircraft using the smoothed position data.

29. The method of claim 28 wherein determining attitude comprises:

performing a body axes geodetic transformation to generate the attitude.

30. The method of claim 29 wherein performing the body axes geodetic transformation comprises:

transforming at least one of bank angle, angle of attack, headings and elevation to at least one of yaw, pitch and roll.

31. The method of claim 30 wherein transforming comprises:

generating the angle of attack using at least one of thrust, weight, dynamic pressure, and load factor; and

generating the heading and the elevation using velocity direction and velocity elevation.

32. The method of claim 31 wherein transforming further comprises:

generating the load factor and the bank angle using transformed acceleration data.

33. The method of claim 32 wherein generating the load factor and the bank angle comprises:

transforming the smoothed position data based on wind axes to provide the transformed acceleration data.

34. The method of claim 31 wherein generating the heading and the elevation comprises:

determining the velocity direction and the velocity elevation using atmospheric and velocity information.

35. The method of claim 34 wherein the atmospheric and velocity information include at least one of atmospheric wind data, atmospheric density, true velocity, sink rate, airspeed, and indicated airspeed.