Navigation apparatus and positioning method thereof

• US 8,214,149 B2
• Filed: 06/08/2009
• Issued: 07/03/2012
• Est. Priority Date: 06/24/2008
• Status: Active Grant

• Current Assignee: Xueshan Technologies Inc. (Wi-LAN Inc.)
• Original Assignee: MStar Semiconductor Incorporated (MediaTek, Inc.)
• Inventors: Lee, Meng-Shu, Liu, Ying-Chuan, Hsu, Yu Hui, Ho, Chien-Wei
• Primary Examiner(s): Beaulieu, Yonel
• Application Number:
  US12/480,140
• Publication Number:
  US 20090319183A1
• Time in Patent Office: 1,121 Days
• Field of Search: 701200-202, 701208-209, 701/527, 701/533, 340/988
• US Class Current: 701/533
• CPC Class Codes: G01C 21/30 Map- or contour-matching
• CPC Class Codes: G01S 19/50 whereby the position solution is constrained to lie upon a particular curve or surface, e.g. for locomotives on railway tracks

Abstract

A positioning method for a navigation apparatus and the navigation apparatus are provided. The positioning method includes steps of receiving a Global Positioning System (GPS) signal; reading a previous position-velocity-time (PVT) data; reading a previous map matching (MMT) result; and computing current PVT data according to at least one of the previous PVT data and the previous MMT result.

Claims

1. A positioning method for a navigation apparatus, comprising steps of:

a) storing a previous positioning parameter and a previous map-matching parameter;

b) receiving a positioning signal;

c) reading the previous positioning parameter and the previous map-matching parameter; and

d) determining a current positioning parameter according to the positioning signal, the previous positioning parameter, and a previous map-matching position value and a previous map-matching azimuth value associated with the previous map-matching parameter.

2. The positioning method as claimed in claim 1, wherein the step (d) is computing the current positioning parameter according to the positioning signal, a previous velocity and a previous time offset associated with the previous positioning parameter, and the previous map-matching position value and the previous map-matching azimuth value associated with the previous map-matching parameter.

3. The positioning method as claimed in claim 1, wherein the step (c) further comprises steps of:

c1) determining whether the previous positioning parameter is valid;

wherein, when it is determined the previous positioning parameter is invalid, the method further comprising;

e) determining an initial positioning parameter, according to the positioning signal received by the navigation apparatus.

4. The positioning method as claimed in claim 1, wherein the step (c) further comprises steps of:

c1) determining whether the previous map-matching parameter is present;

wherein, when it is determined the previous map-matching parameter is absent, the current positioning parameter is computed in the step (d) according to the previous positioning parameter and the positioning signal.

5. The positioning method as claimed in claim 1, further comprising:

f) determining whether the current positioning parameter is valid;

wherein, when it is determined the current positioning parameter is invalid, the current positioning parameter is computed in the step (d) according to the previous positioning parameter and the positioning signal.

6. The positioning method as claimed in claim 1, the navigation apparatus comprising a map data, the method further comprising:

g) selectively computing the current map-matching parameter according to the map data and the current positioning parameter.

7. The positioning method as claimed in claim 6, the positioning parameter comprising a current position value and a current azimuth value, the step (g) further comprising steps of:

g1) defining a coverage according to the current position value and a predetermined radius, and selecting a plurality of routes from the map data according to the coverage;

g2) determining whether a planned route is present;

g3) determining whether any of the routes is the planned route when the planned route is present;

g4) when the planned route is identified from the routes, defining a range of a covered azimuth according to the current azimuth value and a first angle, and subtracting a distance between the current position value and the planned route by a predetermined length;

g5) when the planned route is absent or unidentified from the routes, defining a range of covered azimuth according to the current azimuth value and a second angle; and

g6) determining the current map-matching parameter according to the current position value, the routes, the current azimuth value and the range of covered azimuth;

wherein, the first angle is larger than the second angle.

8. The positioning method as claimed in claim 7, wherein the step (g6) comprises a step of:

g6-1) setting a weight of each of the routes according to the current position value, the current azimuth value, the routes and the range of covered azimuth.

9. The positioning method as claimed in claim 8, further comprising a step of:

g6-2) selecting a route having the largest weight;

calibrating the current position value to the selected route; and

using the calibrated position value as a current position value of the current map-matching parameter, and the azimuth value of the selected route as a current azimuth value of the current map-matching parameter.

10. The positioning method as claimed in claim 8, wherein the step (g6-1) comprises steps of:

g6-1-1) designating a first weight to each of the routes according to respective distances between the routes and the current position value;

g6-1-2) matching the azimuth value of each of the routes with the range of covered azimuth, and designating a second weight to each of the routes according to respective differences between the azimuth values of each of the routes and the current azimuth value; and

g6-1-3) setting the weight of each of the routes according to the first weight and the second weight of each of the routes.

11. A navigation apparatus, comprising:

a first storage medium, stored with a previous positioning parameter data and a previous map-matching parameter;

a receiver, for receiving a positioning signal; and

a computing unit, coupled to the first storage medium and the receiver, for reading the previous positioning parameter and the previous map-matching parameter, and for determining a current positioning parameter according to the positioning signal, the previous positioning parameter, and a previous map-matching position value and a previous map-matching azimuth value associated with the previous map-matching parameter.

12. The navigation apparatus as claimed in claim 11, wherein the computing unit computes the current positioning parameter according to the positioning signal, a previous velocity and a previous time offset of the previous positioning parameter, and the previous map-matching position value and the previous map-matching azimuth value of the previous map-matching parameter.

13. The navigation apparatus as claimed in claim 11, wherein the computing unit computes the current positioning parameter using a Kalman filter.

14. The navigation apparatus as claimed in claim 11, further comprising:

a second storage medium, for storing a map data, and selectively computing the current map-matching parameter according to the map data and the current positioning parameter.

15. The navigation apparatus as claimed in claim 14, wherein the computing unit comprises:

a first computing module, coupled to the first storage medium and the receiver, for computing the current positioning parameter according to the positioning signal, the previous positioning parameter and the previous map-matching parameter; and

a second module, coupled to the second storage medium and the PVT computing module, for computing the current map-matching parameter according to the current positioning parameter and the map data.

16. The navigation apparatus as claimed in claim 15, wherein the computing unit further comprises:

a third module, coupled to the second storage medium and the second module, for generating a planned route;

wherein, the second module computes the current map-matching parameter further according to the planned route.

17. The navigation apparatus as claimed in claim 12, wherein when the previous positioning parameter is invalid, the computing unit computing an initial positioning parameter according to the positioning signal by means of a root-mean-square (RMS) algorithm.