GNSS navigation solution integrity in non-controlled environments

• US 20060047413A1
• Filed: 12/02/2004
• Published: 03/02/2006
• Est. Priority Date: 12/02/2003
• Status: Abandoned Application

• Current Assignee: GMV Aerospace and Defence, S.A.
• Original Assignee: GMV Aerospace and Defence, S.A.
• Inventors: Schortmann, Joaquin Cosmen, Lopez, Manuel Toledo, Lopez, Nestor Zarraoa, Martin Piedelobo, Juan Ramon
• Application Number:
  US11/002,853
• Publication Number:
  US 20060047413A1
• Time in Patent Office: Days
• US Class Current: 701/200
• CPC Class Codes: G01S 19/20 Integrity monitoring, fault detection or fault isolation of space segment
• CPC Class Codes: G01S 19/396 Determining accuracy or reliability of position or pseudorange measurements
• CPC Class Codes: G01S 19/42 Determining position

Abstract

The present invention consists of a method to ensure the integrity of the navigation solution even when the user is in a non controlled environment as it is the case of urban and road applications. The method requires the existence of a Signal In Space with guaranteed integrity as the one today provided by SBAS systems or from GBAS, Galileo or GPS-III in the future. The invention covers the algorithms to detect and isolate errors present in non controlled environments such as multipath and compute resulting position error bounds with the required level of integrity. This invention substantially increases the field of application of satellite navigation systems with associated integrity to the so-called liability critical applications.

Claims

1. An algorithm called GARAI (GNSS-Aided Receiver Autonomous Integrity) that ensures the navigation solution integrity based on a GNSS signal with ensured service integrity based on SBAS and that is specifically designed to work in non-controlled environments such as urban areas or roads.

2. Same algorithm as in item 1 where signal integrity is provided by Galileo instead of by SBAS systems.

3. Same algorithm as in item 1 where signal integrity is provided by GBAS or other local integrity elements.

4. Same algorithm as in item 1 where signal integrity is provided by other GNSS systems as, potentially, GPS-III.

5. An algorithm to ensure detection and exclusion of reflected measurements and able to compute velocity and associated protection levels, this algorithm is an essential part of the mentioned GARAI algorithm.

6. Same algorithm as in item 5 where the algorithm (Carrier Phase RAIM) excludes multipath reflected measurements based o the inconsistencies among observed Doppler effect and velocity vector.

7. An algorithm that characterise the local pseudorange errors (multipath and receiver noise) in terms of associated variance, measurements with excessive multipath errors are excluded for later computations and multipath is mitigated in valid measurements, this algorithm is essential part of the mentioned GARAI algorithm.

8. Same algorithm as in item 7 where ionospheric errors are compensated based on two frequencies measurements instead of on SBAS provided ionospheric model.

9. Same algorithm as in item 7 where the smoothed pseudoranges are computed based on a real-time filter instead of on a sequential interpolation filter.

10. An algorithm that computes the weights of the pseudorrange errors based on the information computed by algorithm described in item 7, this algorithm is essential part of the mentioned GARAI algorithm.

11. An improved algorithm for computation of “

Protection level computation based on weighted RAIM for multiple failure case”

, this algorithm is essential part of the mentioned GARAI algorithm.

12. An algorithm as the one identified in item 12 where computation of integrity considers the vehicle velocity and does not compute solutions where vehicle has been stopped during a certain period of time.

13. An Enhanced Performance Integrity algorithm that allows improving the integrity and/or availability performance of the algorithms defined in item 1 by combining the computed position and protection levels with external GIS information related to roads and streets where this information has been checked to ensure its integrity.

14. An algorithm as the one identified in item 13 where external information is related to the topography of the surface (3D information).

15. An algorithm that allows improving the integrity and/or availability performance of the algorithm defined in item 1 where information from different mobile units located in a certain restricted area are combined to cross-check the quality of the provided measurements.