Carrier-phase-based relative positioning device

• US 7,026,982 B2
• Filed: 01/16/2004
• Issued: 04/11/2006
• Est. Priority Date: 12/19/2001
• Status: Expired due to Term

• Current Assignee: Furuno Electric Co, Ltd
• Original Assignee: Furuno Electric Co, Ltd
• Inventors: Toda, Hiroyuki, Fukuda, Masaru, Fujisawa, Naomi
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US10/758,034
• Publication Number:
  US 20040145518A1
• Time in Patent Office: 816 Days
• Field of Search: 342/357.01, 342/357.02, 342/357.04, 342/357.06, 701/213, 701/215
• US Class Current: 342/357.27
• CPC Class Codes: G01S 19/36 relating to the receiver frond end
• CPC Class Codes: G01S 19/44 Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method
• CPC Class Codes: G01S 19/55 Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method

Abstract

A carrier-phase-based relative positioning device employs a signal processing method which makes it possible to continue estimation of integer ambiguity values even when the number of positioning satellites has changed, determine an integer ambiguity value by efficiently verifying the integer ambiguities in a short time, and calculate a baseline vector. The positioning device includes an integer ambiguity resolving section which determines integer ambiguities of single or double phase differences using a Kalman filter and lambda notation. The Kalman filter is used to calculate estimated values of floating ambiguities and the lambda notation is used to calculate estimated values of the integer ambiguities based on the floating ambiguities. A candidate of a potentially true integer ambiguity that is considered most reliable is determined through various verification processes. When the number of positioning satellites has increased or decreased, or when a reference satellite has been switched, a floating ambiguity after the change in satellite information is estimated from a baseline vector estimated before the change.

Claims

1. A carrier-phase-based relative positioning device, comprising:

at least two antennas mounted on a mobile vehicle or on a mobile vehicle and at a fixed location, one of said antennas being specified as a reference antenna; and

means for estimating an integer ambiguity and a baseline vector from a result of observation of a single phase difference or a double phase difference based on radio waves transmitted by a plurality of position satellites and received by said antennas,

wherein a new integer ambiguity is estimated from the previously estimated baseline vector or integer ambiguity when the number of positioning satellites has changed or when the reference position satellite has been switched.

2. The carrier-phase-based relative positioning device according to claim 1, further comprising a means for verifying and determining said integer ambiguity.

3. The carrier-phase-based relative positioning device according to claim 2, wherein when the number of positioning satellites has increased, the new integer ambiguity estimated only from said baseline vector estimated before the number of positioning satellites has increased.

4. The carrier-phase-based relative positioning device according to claim 2, wherein when the number of positioning satellites has decreased, the integer ambiguity after the reduction in the number of positioning satellites is estimated by excluding an estimated value of the integer ambiguity derived from the positioning satellite which has become unobservable.

5. The carrier-phase-based relative positioning device according to claim 2, wherein the double phase difference is used for estimating the integer ambiguity and, when the reference position satellite has been switched, the integer ambiguity after the switching of the reference position satellite is estimated by using a difference operation method in response to the reference position satellite switching.

6. The carrier-phase-based relative positioning device according to one of claims 3 to 5 or 2, wherein said means for verifying and determining the integer ambiguity determines the integer ambiguity when the reliability of the integer ambiguity has been verified a specific number of times from its successively detected estimated values.

7. The carrier-phase-based relative positioning device according to one of claims 3 to 5 or 2, wherein said means for verifying and determining the integer ambiguity determines the integer ambiguity when the same estimated value of the integer ambiguity has been successively detected a specific number of times.

8. The carrier-phase-based relative positioning device according to claim 2, wherein said positioning device uses a Kalman filter for estimating a floating ambiguity and the baseline vector from which the integer ambiguity is determined.

9. The carrier-phase-based relative positioning device according to claim 2, wherein said means for estimating and determining the integer ambiguity based on a floating ambiguity uses lambda notation.

19. The carrier-phase-based relative positioning device according to claim 1, wherein when the number of positioning satellites has increased, the new integer ambiguity is estimated only from said baseline vector estimated before the number of positioning satellites has increased.

20. The carrier-phase-based relative positioning device according to claim 1, wherein when the number of positioning satellites has decreased, the integer ambiguity after the reduction in the number of positioning satellites is estimated by excluding an estimated value of the integer ambiguity derived from the positioning satellite which has become unobservable.

21. The carrier-phase-based relative positioning device according to claim 1, wherein the double phase difference is used for estimating the integer ambiguity and, when the reference position satellite has been switched, the integer ambiguity after the switching of the reference position satellite is estimated by using a difference operation method in response to the reference position satellite switching.

22. The carrier-phase-based relative positioning device according to claim 1, wherein said positioning device uses a Kalman filter for estimating a floating ambiguity and the baseline vector from which the integer ambiguity is determined.

23. The carrier-phase-based relative positioning device according to claim 1, wherein said means for estimating and determining the integer ambiguity based on the floating ambiguity uses lambda notation.

10. A method to determine a relative position of a device that includes at least two antennas mounted on a mobile vehicle or on a mobile vehicle and at a fixed location, one of said antennas being specified as a reference antenna, the method comprising:

estimating an integer ambiguity and a baseline vector from a result of observation of a single phase difference or a double phase difference based on radio waves transmitted by a plurality of position satellites and received by said antennas,

wherein a new integer ambiguity is estimated from the previously estimated baseline vector or integer ambiguity when the number of positioning satellites has changed or when the reference position satellite has been switched.

11. The method according to claim 10, further comprising verifying and determining the integer ambiguity.

12. The method of claim 11, wherein when the number of positioning satellites has increased, said estimating step includes estimating the new integer ambiguity only from the baseline vector estimated before the number of positioning satellites has increased.

13. The method of claim 11, wherein when the number of positioning satellites has decreased, said estimating step includes estimating the new integer ambiguity by excluding an estimated value of the integer ambiguity derived from the positioning satellite which has become unobservable.

14. The method of claim 11, wherein the double phase difference is used for estimating the integer ambiguity and, when the reference position satellite has been switched, said estimating step includes estimating the integer ambiguity by using a difference operation method in response to the reference position satellite switching.

15. The method according to one of claims 12 to 14 or 11, wherein the verifying and determining the integer ambiguity further comprises determining the integer ambiguity when the reliability of the integer ambiguity has been verified a specific number of times from its successively detected estimated values.

16. The method according to one of claims 12 to 14 or 11, wherein the verifying and determining the integer ambiguity further comprises determining the integer ambiguity when a same estimated value of the integer ambiguity has been successively detected a specific number of times.

17. The method of claim 11, wherein said estimating step includes using a Kalman filter for estimating a floating ambiguity and the baseline vector from which the integer ambiguity is determined.

18. The method of claim 11, wherein said estimating step includes using a lambda notation when determining the integer ambiguity based on a floating ambiguity.