Portable device for determining azimuth

• US 9,395,187 B2
• Filed: 07/10/2014
• Issued: 07/19/2016
• Est. Priority Date: 07/10/2013
• Status: Active Grant

• Current Assignee: Atlantic Inertial Systems Incorporated (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Atlantic Inertial Systems Incorporated (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Sheard, John Keith, Faulkner, Nicholas
• Primary Examiner(s): Marc, McDieunel
• Assistant Examiner(s): Stroud, James E
• Application Number:
  US14/327,679
• Publication Number:
  US 20150019129A1
• Time in Patent Office: 740 Days
• Field of Search: 701/472
• US Class Current: 1/1
• CPC Class Codes: G01C 15/00 Surveying instruments or accessories not provided for in groups G01C1/00 - G01C13/00
• CPC Class Codes: G01C 17/00 Compasses; Devices for ascertaining true or magnetic north for navigation or surveying purposes using gyroscopic effect G01C19/00
• CPC Class Codes: G01C 19/38 with north-seeking action by other than magnetic means, e.g. gyrocompasses using earth's rotation
• CPC Class Codes: G01C 21/005 with correlation of navigation data from several sources, e.g. map or contour matching G01C21/30 takes precedence
• CPC Class Codes: G01C 21/10 by using measurements of speed or acceleration G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01S 19/35 Constructional details or hardware or software details of the signal processing chain
• CPC Class Codes: G01S 19/393 Trajectory determination or predictive tracking, e.g. Kalman filtering
• CPC Class Codes: G01S 19/53 Determining attitude
• CPC Class Codes: G01S 19/54 using carrier phase measurements; using long or short baseline interferometry

Abstract

A device is described herein for determining azimuth comprising a MEMS inertial measurement unit (IMU), a GPS system comprising a GPS antenna and receiver, and a processor configured to receive data from said IMU and from said GPS system, said processor being configured to process said IMU data and said GPS data to derive a true north reference based on said IMU data and said GPS data. A method for determining azimuth is also described herein.

Claims

1. A device for determining azimuth comprising:

a MEMS inertial measurement unit (IMU),

a GPS system comprising a GPS antenna and receiver

a processor configured to receive data from said IMU and from said GPS system, said processor being configured to process said IMU data and said GPS data to derive a true north reference based on said IMU data and said GPS data;

wherein said GPS antenna and said IMU are rigidly connected to each other and located at a distance of 5 cm or less from each other so that they experience the same motion when said device is moved; and

wherein said processor is configured to compare said IMU data with said GPS data to derive said true north reference.

2. The device of claim 1 wherein said device is configured to be hand held.

3. The device of claim 1 wherein said device is configured to produce said IMU data and said GPS data due to movement of said device.

4. The device of claim 3 wherein said movement comprises oscillatory translation of said device.

5. The device of claim 3 wherein said movement comprises inversion of said device and oscillatory translation of said device.

6. The device of claim 3 wherein said IMU data and said GPS data correspond to first and second independent measurements of the same movement of said device.

7. The device of claim 1 wherein said IMU comprises three MEMS accelerometers and said data received from said IMU comprises inertial accelerometer data.

8. The device of claim 1 wherein said IMU comprises three MEMS gyroscopes and said data received from said IMU comprises angular rate data.

9. A method for determining azimuth comprising

providing a device that comprises a MEMS inertial measurement unit (IMU), a GPS system and a processor,

wherein said GPS system comprises a GPS antenna and receiver, wherein said GPS antenna and said IMU are rigidly connected to each other and located at a distance of 5 cm or less from each other so that they experience the same motion when said device is moved,

said method further comprising the steps of moving said device, and

transmitting said IMU data and said GPS data to said processor,

and said processor processing said IMU data and said GPS data and deriving a true north reference based on said IMU and GPS data.

10. The method of claim 9 wherein said step of moving said device comprises creating oscillatory translation of said device.

11. The method of claim 10, wherein said step of moving said device comprises inverting said device and creating oscillatory translation of said device.

12. The method of claim 9 wherein said GPS data comprises GPS phase carrier measurements.

13. The method of claim 12 wherein said GPS data further comprises satellite code data.

14. The method of claim 9, comprising the step of comparing said IMU data with said GPS data to derive said true north reference.

15. The method of claim 9 comprising the step of integrating said IMU data and comparing said integrated IMU data with said GPS data to derive said true north reference.