Accurate positioning system for a vehicle and its positioning method

• US 20080082265A1
• Filed: 01/11/2007
• Published: 04/03/2008
• Est. Priority Date: 09/15/2006
• Status: Active Grant

• Current Assignee: SIN ETKE Technology Company Limited
• Original Assignee: SIN ETKE Technology Company Limited
• Inventors: Lee, Chun-Chung, Chen, Kuo-Rong, Yang, Ming-Wen
• Granted Patent: US 7,831,388 B2
• Time in Patent Office: Days
• US Class Current: 701/213
• 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 the current GPS coordinates of the vehicle once per every first time interval;

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

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

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

wherein;

the controller obtains the azimuth from the Gyro sensor and the vehicle speed signal from the vehicle speedometer and reads in the GPS coordinates from the GPS, calculates a reference coordinates of the vehicle subject to the data of the fetched azimuth, vehicle speed signal and GPS coordinates, and assigns the reference coordinates thus calculated to be an accurate coordinates at the corresponding time point for output;

the controller also obtains the azimuth from the Gyro sensor and the vehicle speed signal from the vehicle speedometer and reads in last accurate coordinates once per every second time interval that is shorter than the first time interval, calculates a reference coordinates of the vehicle subject to the data of the fetched azimuth, vehicle speed signal and last accurate coordinates, and assigns the reference coordinates thus calculated to be the accurate coordinates at the corresponding time point for output;

after the GPS has outputted a next GPS coordinates as the first time interval has expired, the controller calculates a next reference coordinates of the vehicle and the distance between the next GPS coordinates and the next reference coordinates, and then compares the distance between the next GPS coordinates and the next reference coordinates to a reference distance, and then assigns the next GPS coordinates to the accurate coordinates for output when the distance between the next GPS coordinates and next reference coordinates is greater than the reference distance, or assigns the next reference coordinates to be the accurate coordinates for output when the distance between the next GPS coordinates and next reference coordinates 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 the analog signal of the azimuth indicative of the current heading direction of the vehicle into a digital signal.

3. The accurate positioning system as claimed in claim 1, wherein the vehicle speed signal 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 respectively and 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 fetched 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 end points of the multiple roads.

9. The accurate positioning system as claimed in claim 8, wherein the multiple road map data further include 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 second.

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

A) obtaining an azimuth of the heading direction of a vehicle, a vehicle speed signal and GPS coordinates, wherein the azimuth is outputted by a Gyro sensor installed in the vehicle;

the vehicle speed signal is outputted by a vehicle speedometer installed in the vehicle;

the GPS coordinates is outputted by a GPS (Global Positioning System) installed in the vehicle once per every first time interval;

B) calculating reference coordinates of the vehicle and assigning the reference coordinates to be the accurate coordinates at the corresponding time point, and outputting the accurate coordinates;

C) obtaining the azimuth of the current heading direction of the vehicle from the Gyro sensor and the vehicle speed signal from the vehicle speedometer and reading in the last accurate coordinates once per every second time interval, wherein the second time interval is shorter than the first time interval;

D) calculating the reference coordinates ofthe vehicle and assigning the calculated reference coordinates to be the current accurate coordinates of the vehicle, and outputting the current accurate coordinates;

E) calculating the next reference coordinates of the vehicle after the GPS has outputted a next GPS coordinates as the first time internal has expired, and then calculating the distance between the next GPS coordinates and the next reference coordinates; and

F) comparing the distance between the next GPS coordinates and the next reference coordinates to a reference distance to be greater or smaller than the reference distance, and assigning the next GPS coordinates to be the next accurate coordinates and outputting the next accurate coordinates when the distance between the next GPS coordinates and the next reference coordinates is greater than the reference distance.

12. The accurate vehicle positioning method as claimed in claim 11, wherein when the distance between the next GPS coordinates and the next reference coordinates is smaller than or equal to the reference distance after comparison during step F), assigning the next reference coordinates to be the next accurate coordinates and outputting the next 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 accurate coordinates and outputting the road map data after step B) and before step C).