Accurate positioning system for a vehicle and its positioning method

• US 7,831,388 B2
• Filed: 01/11/2007
• Issued: 11/09/2010
• Est. Priority Date: 09/15/2006
• Status: Expired due to Fees

• Current Assignee: SIN ETKE Technology Company Limited
• Original Assignee: SIN ETKE Technology Company Limited
• Inventors: Chen, Kuo-Rong, Yang, Ming-Wen, Lee, Chun-Chung
• Primary Examiner(s): MANCHO, RONNIE M
• Application Number:
  US11/651,992
• Publication Number:
  US 20080082265A1
• Time in Patent Office: 1,398 Days
• Field of Search: 701/216, 701/217, 701/220, 701/213, 701/214, 701/215, 342/357.14, 342/457, 342/357.02, 702/92, 702/94, 731/78.R, 340/988
• US Class Current: 701/216
• CPC Class Codes: G01C 21/26 specially adapted for navigation in a road network
• CPC Class Codes: G01S 19/49 whereby the further system is an inertial position system, e.g. loosely-coupled

Abstract

An accurate positioning system installed in a vehicle is disclosed to include a GPS, a Gyro sensor, a vehicle speedometer, and a controller. When the GPS outputs a next GPS coordinates, the controller calculates a next reference coordinates subject to the azimuth signal outputted from the Gyro sensor and the vehicle speed signal outputted from the vehicle speedometer and calculates the distance between the next GPS coordinates and the next reference coordinates, and then assigns the GPS coordinates to be the next accurate coordinates for output when the distance between the next GPS coordinates and the next reference coordinates surpasses a reference distance, or assigns the next reference coordinates to be the next accurate coordinates for output when the distance between the next GPS coordinates and the next reference coordinates is smaller than or equal to the reference distance.

Claims

1. An accurate positioning system installed in a vehicle, comprising:

a GPS (Global Positioning System), the GPS outputting current first, second, third, etc GPS coordinates of the vehicle in that order once per every first time interval;

a Gyro sensor, the Gyro sensor outputting azimuth signals indicative of the currently heading direction of the vehicle;

a vehicle speedometer, the vehicle speedometer outputting vehicle speed signals indicative of the current speed of the vehicle; and

a controller electrically connected to the GPS, the Gyro sensor, and the vehicle speedometer;

wherein;

the controller obtains a first azimuth signal from the Gyro sensor, a first vehicle speed signal from the vehicle speedometer, and reads in first GPS

coordinates outputted at the first time interval from the GPS to calculate first reference coordinates of the vehicle, wherein the controller refers to the first reference coordinates thus calculated as first accurate coordinates at a time of output of the first accurate coordinates;

the controller obtains second azimuth signals from the Gyro sensor, second vehicle speed signals from the vehicle speedometer, and reads in the first accurate coordinates to calculate second reference coordinates of the vehicle, wherein the controller refers to the second reference coordinates thus calculated as second accurate coordinates at time of output of the second accurate coordinates;

the controller calculates first, second, third, and fourth accurate coordinates in that order once per second time interval, wherein the second time interval is shorter than the first time interval;

after the GPS has outputted second GPS coordinates as the first time interval expires, the controller calculates the fourth reference coordinates of the vehicle, wherein the controller further calculates a distance between the second GPS coordinates and the fourth reference coordinates, and then compares the calculated distance to a reference distance, and then refers to the second GPS coordinates as fourth accurate coordinates for output when the calculated distance is greater than the reference distance, or refers to the fourth reference coordinates as the fourth accurate coordinates for output when the calculated distance is smaller than the reference distance.

2. The accurate positioning system as claimed in claim 1, further comprising an analog-to-digital converter electrically connected between the Gyro sensor and the controller and adapted to convert outputted analog azimuth signals, indicative of the current heading direction of the vehicle, into digital signals.

3. The accurate positioning system as claimed in claim 1, wherein the vehicle speed signals of the vehicle speedometer includes a series of pulse signals, the series of pulse signals having a frequency directly proportional to the current running speed of the vehicle.

4. The accurate positioning system as claimed in claim 1, wherein the controller comprises memory means having stored therein the accurate coordinates and the reference distance.

5. The accurate positioning system as claimed in claim 4, further comprising an adjusting device electrically connected to the controller and adapted to edit the reference distance in the memory means.

6. The accurate positioning system as claimed in claim 5, wherein the adjusting device is a keypad.

7. The accurate positioning system as claimed in claim 1, further comprising a display screen and an electronic map database both electrically connected to the controller, the electronic map database having stored therein multiple road map data, wherein the controller reads in road map data from the electronic map database relative to the accurate coordinates, and outputs the read road map data to the display screen for display.

8. The accurate positioning system as claimed in claim 7, wherein the multiple road map data of the electronic map database include names of multiple roads and the coordinates of starting points and ending points of the multiple roads.

9. The accurate positioning system as claimed in claim 8, wherein the multiple road map data further includes multiple road links and multiple surrounding facilities corresponding to the names of multiple roads.

10. The accurate positioning system as claimed in claim 1, wherein the first time internal is one second, and the second time interval is 0.25 seconds.

11. An accurate vehicle positioning method comprising the steps of:

A) obtaining a current azimuth of a heading direction of a vehicle, a current vehicle speed signal, and current GPS coordinates, wherein the azimuth is outputted by a Gyro sensor installed in the vehicle, further wherein the vehicle speed signal is outputted by a vehicle speedometer installed in the vehicle, and further wherein the GPS coordinates are outputted by a GPS (Global Positioning System) installed in the vehicle, the GPS coordinates outputted once per every first time interval;

B) calculating first GPS coordinates of the vehicle and referring to the GPS coordinates as first accurate coordinates at a first time interval;

C) next, obtaining the current azimuth of the current heading direction of the vehicle from the Gyro sensor and the current vehicle speed signal from the vehicle speedometer and reading in the first accurate coordinates to calculate second accurate coordinates after a second time interval, wherein the second time interval is shorter than the first time interval;

D) next, obtaining the current azimuth of the current heading direction of the vehicle from the Gyro sensor and the current vehicle speed signal from the vehicle speedometer and reading in the second accurate coordinates to calculate third accurate coordinates after a next second time interval, wherein the next second time interval is shorter than the first time interval;

E) next, obtaining the current azimuth of the current heading direction of the vehicle from the Gyro sensor and the current vehicle speed signal from the vehicle speedometer and reading in the third accurate coordinates to calculate fourth reference coordinates after a next second time interval, wherein the next second time interval is shorter than the first time interval;

F) next, outputting second GPS coordinates at expiry of a next first time interval, and then calculating a distance between the second GPS coordinates and the fourth reference coordinates; and

G) next, comparing the calculated distance between the second GPS coordinates and the fourth reference coordinates to a reference distance to determine if the calculated distance is greater or smaller than the reference distance, and referring to the second GPS coordinates as the fourth accurate coordinates when the calculated distance between the second GPS coordinates and the fourth reference coordinates is greater than the reference distance, and outputting the fourth accurate coordinates.

12. The accurate vehicle positioning method as claimed in claim 11, wherein when the calculated distance between the second GPS coordinates and the fourth reference coordinates is smaller than or equal to the reference distance after comparison during step G), assigning the fourth reference coordinates to be the fourth accurate coordinates and outputting the fourth accurate coordinates.

13. The accurate vehicle positioning method as claimed in claim 11, further comprising a sub step A1) of converting the analog signal of the azimuth of the heading direction of the vehicle into a digital signal after step A) and before step B).

14. The accurate vehicle positioning method as claimed in claim 13, wherein the sub step A1) is to use an analog-to-digital converter to convert the analog signal of the azimuth of the heading direction of the vehicle into a digital signal.

15. The accurate vehicle positioning method as claimed in claim 11, further comprising a sub step B1) of reading in a road map data from an electronic map database subject to the first accurate coordinates and outputting the road map data after step B) and before step C).