Apparatus and method for detecting vehicle location in navigation system

• US 20050021229A1
• Filed: 07/22/2004
• Published: 01/27/2005
• Est. Priority Date: 07/21/2003
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Joe, Moon Jeung, Jung, Mun Ho, Yi, Dong Hoon, Lee, Han Sung
• Granted Patent: US 7,349,802 B2
• Time in Patent Office: Days
• US Class Current: 701/210
• CPC Class Codes: G01C 21/30 Map- or contour-matching

Abstract

When a vehicle location is estimated using only detection signals from a sensor unit installed on a vehicle since the value of dilution of precision (DOP) of a navigation message received by a GPS receiver is equal to or greater than a predetermined threshold in a navigation system, the vehicle location is precisely estimated using a traveled distance, a travel angle difference, and lateral and longitudinal inclinations of the vehicle. The value of DOP of the navigation message received by the GPS receiver is compared with the predetermined threshold. If the value of DOP is less than the predetermined threshold, reference vehicle location information is set using the navigation message. If the value of DOP is equal to or greater than the predetermined threshold, the reference vehicle location information is set using vehicle location information just previously map-matched and the detection signals from the sensor unit. The vehicle location is estimated using the set reference vehicle location information and the detection signals from the sensor unit and then map-matched on a digital map stored in a map data storage unit, thereby displaying the map-matched results on a display unit.

Claims

1. An apparatus for detecting a vehicle location in a navigation system, comprising:

a GPS receiver for receiving a navigation message transmitted by a GPS satellite;

a map data storage unit for storing a digital map data therein;

a sensor unit for detecting a travel direction and a traveled distance of a vehicle and lateral and longitudinal inclinations of a road on which the vehicle travels;

a control unit for comparing the value of DOP of the navigation message received by the GPS receiver with a predetermined threshold, setting reference vehicle location information from vehicle location information detected using the navigation message if the value of DOP is less than the predetermined threshold, or determining the reference vehicle location information by storing vehicle location information map-matched to the digital map data when the just previous value of DOP was less than the predetermined threshold, by accumulating detection signals from the sensor unit, and by using the stored vehicle location information and the accumulated detection signals from the sensor unit if the value of DOP is equal to or greater than the predetermined threshold, estimating the vehicle location using the determined reference vehicle location information and the detection signals from the sensor unit, and map-matching the estimated vehicle location to the digital map data stored in the map data storage unit; and

a display unit for displaying the digital map data and vehicle location map-matched by the control unit on a screen thereof.

2. The apparatus as claimed in claim 1, wherein the control unit comprises:

a map-matched result extraction section for extracting the vehicle location information on results of the map-matching of the vehicle location to the digital map data, and extracting a status code for notifying whether the extracted vehicle location information is location information determined using the navigation message;

a location information extraction section for extracting the vehicle location information and the DOP using the navigation message received by the GPS receiver;

a travel information extraction section for extracting vehicle travel information using the detection signals from the sensor unit;

a reference location information determination section for determining the reference vehicle location information using the vehicle location information extracted by the location information extraction section if the value of DOP extracted by the location information extraction section is less than the predetermined threshold, or determining the reference vehicle location information by storing the vehicle location information extracted by the map-matched result extraction section when the just previous value of DOP was less than the predetermined threshold, by accumulating the detection signals from the sensor unit, and by using the stored vehicle location information and the accumulated detection signals from the sensor unit if the extracted value of DOP is equal to or greater than the predetermined threshold, and for generating a status code for notifying whether the determined reference vehicle location information is location information determined using the navigation message;

a dead reckoning section for detecting current vehicle location information by performing dead-reckoning using the reference vehicle location information determined by the reference location information determination section and the vehicle travel information extracted by the travel information extraction section; and

a map-matching section for map-matching the vehicle location information detected by the dead reckoning section to the digital map data stored in the map data storage unit, outputting the map-matched results to the display unit, and providing information on the map-matched results to the map-matched result extraction section to extract the vehicle location information according to the map-matching.

3. The apparatus as claimed in claim 2, wherein the travel information extracted by the travel information extraction section includes a travel angle difference, a traveled distance, and lateral and longitudinal inclinations of the vehicle.

4. A method for detecting a vehicle location in a navigation system, comprising the steps of:

extracting, by a map-matched result extraction section, vehicle location information by receiving vehicle location information map-matched to digital map data from a map-matching section, extracting, by a location information extraction section, vehicle location information and DOP using a navigation message received by a GPS receiver, and extracting, by a travel information extraction section, vehicle travel information using detection signals from a sensor unit installed on a vehicle;

determining the vehicle location information extracted by the location information extraction section as reference vehicle location information, or determining the reference vehicle location information by storing the vehicle location information extracted by the map-matched result extraction section, accumulating the detection signals from the sensor unit, and using the stored vehicle location information and the accumulated detection signals from the sensor unit, according to the extracted value of DOP;

performing, by a dead reckoning section, dead reckoning using the vehicle travel information extracted by the travel information extraction section and the determined reference vehicle location information to extract current vehicle location information; and

map-matching, by the map-matching section, the current vehicle location information extracted by the dead reckoning section to the digital map data, displaying the map-matched results on a display unit, and providing the map-matched results to the map-matched result extraction section to extract the map-matched vehicle location information.

5. The method as claimed in claim 4, wherein the step of determining the reference vehicle location information comprises the steps of:

comparing the value of DOP with a predetermined threshold;

if it is determined from the comparison that the value of DOP is less than the predetermined threshold, determining the vehicle location information extracted by the location information extraction section as the reference vehicle location information; and

if it is determined from the comparison that the value of DOP is equal to or greater than the predetermined threshold, storing the vehicle location information extracted by the map-matched result extraction section when the just previous value of DOP was less than the predetermined threshold, accumulating the detection signals from the sensor unit, and determining the reference vehicle location information using the stored vehicle location information and the accumulated detection signals from the sensor unit.

6. The method as claimed in claim 4, wherein the travel information extracted by the travel information extraction section includes a travel angle difference, a traveled distance, and lateral and longitudinal inclinations of the vehicle.

7. The method as claimed in claim 6, wherein the extraction of a traveled distance from the vehicle travel information is performed by the steps of determining a travel speed of the vehicle using the number of pulse signals per unit time generated by an odometer of the sensor unit according to travel of the vehicle, determining a traveled-distance conversion coefficient varying according to the determined travel speed, and calculating a traveled distance per unit time of the vehicle.

8. The method as claimed in claim 7, wherein the step of determining the traveled-distance conversion coefficient comprises the steps of:

determining whether the travel speed of the vehicle is equal to or greater than a predetermined speed;

if it is determined that the travel speed of the vehicle is not equal to or greater than the predetermined speed, determining a predetermined constant as the traveled-distance conversion coefficient; and

if it is determined that the travel speed of the vehicle is equal to or greater than the predetermined speed, determining the traveled-distance conversion coefficient through calculation using a predetermined logarithmic function including the number of pulse signals per unit time generated by the odometer.

9. The method as claimed in claim 8, wherein the traveled-distance conversion coefficient is calculated using formula 1 as follows:

$\begin{array}{cc}\begin{array}{c}\text{Traveled}-\\ \text{distance <br><br> <br><br>conversion}\\ \mathrm{coefficient}\end{array}=a+\frac{\begin{array}{c}\text{log(number <br><br> <br><br>of <br><br> <br><br>pulse}\\ \text{signals <br><br> <br><br>per <br><br> <br><br>unit <br><br> <br><br>time)}\end{array}}{b}& \left(1\right)\end{array}$

where a and b are empirical constants.

10. The method as claimed in claim 7, wherein the traveled distance per unit time of the vehicle is calculated by multiplying the number of pulse signals per unit time generated by the odometer by the traveled-distance conversion coefficient.

11. The method as claimed in claim 6, wherein the extraction of the current vehicle location information is performed by the steps of:

receiving a travel angle difference and the traveled distance of the vehicle, and lateral and longitudinal inclinations of a road on which the vehicle travels from the sensor unit;

calculating a traveled distance per unit time using the received traveled distance;

correcting the travel angle of the vehicle using the received travel angle difference and the received lateral and longitudinal inclinations;

correcting the traveled distance per unit time using the received lateral and longitudinal inclinations; and

determining a current vehicle location from a previous vehicle location using the corrected travel angle and the corrected traveled distance per unit time.

12. The method as claimed in claim 11, wherein the travel angle of the vehicle is corrected using formula 4 as follows:

$\begin{array}{cc}A=A_{-1}+\frac{\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\theta <br><br>}}{\cos <br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\theta <br><br>}}_x\times <br><br>\cos <br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\theta <br><br>}}_y}& \left(4\right)\end{array}$

where A is a corrected current travel angle of the vehicle, A<sub>−

1</sub> is a previous travel angle, Δ

θ

is a travel angle difference of the vehicle detected by the sensor unit, and θ

_x and θ

_y are lateral and longitudinal inclinations of the road on which the vehicle travels.

13. The method as claimed in claim 11, wherein the traveled distance per unit time is corrected using formula 3 as follows:

D=d×

cos θ

_y  

 

(3)

where D is a corrected traveled distance per unit time of the vehicle, d is the traveled distance per unit time, and θ

_y is a longitudinal inclination of the road on which the vehicle travels.

14. The method as claimed in claim 11, wherein the current vehicle location is determined using formula 5 as follows:

P_x=P<sub>x−

1</sub>+D×

cos A
P_y=P<sub>y−

1</sub>+D×

sin A  

 

(5)

where P_x and P_y are corrected current longitude and latitude coordinates of the vehicle, P<sub>x−

1</sub> and P<sub>y−

1</sub> are longitude and latitude coordinates of the vehicle detected prior to the unit time, D is a corrected traveled distance per unit time of the vehicle, and A is a corrected travel angle of the vehicle.

15. The method as claimed in claim 4, wherein the extraction of the current vehicle location information is performed by the steps of:

extracting an azimuth of a road on which the vehicle travels from the digital map data, and calculating a traveled distance per unit time of the vehicle;

estimating current longitude and latitude coordinates of the vehicle using the azimuth of the road, the traveled distance per unit time of the vehicle, and just previously estimated longitude and latitude coordinates of the vehicle;

selecting a location and a road where the vehicle will be matched on a digital map using the extracted azimuth of the road and the estimated longitude and latitude coordinates of the vehicle; and

matching the vehicle at the selected location and road and displaying the matched results.

16. The method as claimed in claim 15, wherein the calculation of the traveled distance per unit time of the vehicle is performed by the steps of determining a travel speed of the vehicle using the number of pulse signals per unit time generated by an odometer of the sensor unit according to the travel of the vehicle, determining a traveled-distance conversion coefficient varying according to the determined travel speed, and calculating the traveled distance per unit time.

17. The method as claimed in claim 16, wherein the step of determining the traveled-distance conversion coefficient comprises the steps of:

determining whether the travel speed of the vehicle is equal to or greater than a predetermined speed;

if it is determined that the travel speed of the vehicle is not equal to or greater than the predetermined speed, determining a predetermined constant as the traveled-distance conversion coefficient; and

if it is determined that the travel speed of the vehicle is equal to or greater than the predetermined speed, determining the traveled-distance conversion coefficient through calculation using a predetermined logarithmic function including the number of pulse signals per unit time generated by the odometer.

18. The method as claimed in claim 17, wherein the traveled-distance conversion coefficient is calculated using formula 1 as follows:

$\begin{array}{cc}\begin{array}{c}\text{Traveled}-\\ \text{distance <br><br> <br><br>conversion}\\ \mathrm{coefficient}\end{array}=a+\frac{\begin{array}{c}\text{log(number <br><br> <br><br>of <br><br> <br><br>pulse}\\ \text{signals <br><br> <br><br>per <br><br> <br><br>unit <br><br> <br><br>time)}\end{array}}{b}& \left(1\right)\end{array}$

where a and b are empirical constants.

19. The method as claimed in claim 16, wherein the step of calculating the traveled distance per unit time of the vehicle comprises the step of making correction using formula 3 as follows:

D=d×

cos θ

_y  

 

(3)

where D is a corrected traveled distance per unit time of the vehicle, d is the traveled distance per unit time, and θ

_y is a longitudinal inclination of the road on which the vehicle travels.

20. The method as claimed in claim 15, wherein the step of selecting the location and the road where the vehicle will be matched comprises the steps of:

acquiring an inclination of the road on which the vehicle travels using the detection signals from the sensor unit;

searching roads within a search radius set with respect to a current vehicle location, extracting roads on which the vehicle location will be matched, and searching attributes of the extracted roads;

if it is determined from the search results of the road attributes that there is no entrance link for an overpass, the current vehicle location is matched on a road closest thereto;

if it is determined from the search results of the road attributes that there is an entrance link for an overpass, comparing the acquired inclination of the road on which the vehicle currently travels with an inclination of a road on which the vehicle has traveled previously;

if it is determined from the comparison that the inclination of the current road is larger than that of the previous road, matching the vehicle location on an overpass; and

if it is determined from the comparison that the inclination of the current road is not larger than that of the previous road, matching the vehicle location on a closest road among roads except overpasses.

24. The method as claimed in claim 20, wherein the traveled distance per unit time of the vehicle is calculated by multiplying the number of pulse signals per unit time generated by the odometer by the traveled-distance conversion coefficient.

25. The method as claimed in claim 20, wherein the step of calculating the traveled distance per unit time of the vehicle comprises the step of making correction using formula 3 as follows:

D=d×

cos θ

_y  

 

(3)

where D is a corrected traveled distance per unit time of the vehicle, d is the traveled distance per unit time, and θ

_y is a longitudinal inclination of the road on which the vehicle travels.

21. A method for determining a vehicle location, comprising the steps of:

determining a travel speed of a vehicle using the number of pulse signals per unit time generated by an odometer of a sensor unit according to travel of the vehicle;

setting a traveled-distance conversion coefficient varying according to the determined travel speed of the vehicle, and calculating a traveled distance per unit time of the vehicle; and

determining the vehicle location by performing dead reckoning using the calculated traveled distance per unit time.

22. The method as claimed in claim 21, wherein the step of calculating the traveled distance per unit time comprises the steps of:

if it is determined that the travel speed of the vehicle is not equal to or greater than a predetermined speed, determining a predetermined constant as the traveled-distance conversion coefficient;

if it is determined that the travel speed of the vehicle is equal to or greater than the predetermined speed, determining the traveled-distance conversion coefficient through calculation using a predetermined logarithmic function including the number of pulse signals per unit time generated by the odometer; and

calculating the traveled distance per unit time of the vehicle using the determined traveled-distance conversion coefficient.

23. The method as claimed in claim 21, wherein the traveled-distance conversion coefficient is calculated using formula 1 as follows:

$\begin{array}{cc}\begin{array}{c}\text{Traveled}-\\ \text{distance <br><br> <br><br>conversion}\\ \mathrm{coefficient}\end{array}=a+\frac{\begin{array}{c}\text{log(number <br><br> <br><br>of <br><br> <br><br>pulse}\\ \text{signals <br><br> <br><br>per <br><br> <br><br>unit <br><br> <br><br>time)}\end{array}}{b}& \left(1\right)\end{array}$

where a and b are empirical constants.

26. A method of detecting a vehicle location in a navigation system, comprising the steps of:

receiving, by a control unit, a travel angle difference and a traveled distance of a vehicle, and lateral and longitudinal inclinations of a road on which the vehicle travels from a sensor unit;

calculating a traveled distance per unit time using the received traveled distance;

correcting a travel angle of the vehicle using the received lateral and longitudinal inclinations of the road;

correcting the traveled distance per unit time using the received lateral and longitudinal inclinations of the road; and

estimating a current vehicle location from a previous vehicle location using the corrected travel angle and the corrected traveled distance per unit time.

27. The method as claimed in claim 26, wherein the travel angle of the vehicle is corrected using formula 4 as follows:

$\begin{array}{cc}A=A_{-1}+\frac{\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\theta <br><br>}}{\cos <br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\theta <br><br>}}_x\times <br><br>\cos <br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\theta <br><br>}}_y}& \left(4\right)\end{array}$

where A is a corrected current travel angle of the vehicle, A<sub>−

1</sub> is a previous travel angle, Δ

θ

is a travel angle difference of the vehicle detected by the sensor unit, and θ

_x and θ

_y are lateral and longitudinal inclinations of the road on which the vehicle travels.

28. The method as claimed in claim 26, wherein the traveled distance per unit time of the vehicle is corrected using formula 3 as follows:

D=d×

cos θ

_y  

 

(3)

where D is a corrected traveled distance per unit time of the vehicle, d is the traveled distance per unit time, and θ

_y is a longitudinal inclination of the road on which the vehicle travels.

29. The method as claimed in claim 26, wherein the current vehicle location is estimated using formula 5 as follows:

P_x=P<sub>x−

1</sub>+D×

cos A
P_y=P<sub>y−

1</sub>+D×

sin A  

 

(5)

where P_x and P_y are corrected current longitude and latitude coordinates of the vehicle, P<sub>x−

1</sub> and P<sub>y−

1</sub> are longitude and latitude coordinates of the vehicle detected prior to the unit time, D is a corrected traveled distance per unit time of the vehicle, and A is a corrected travel angle of the vehicle.

30. A method for detecting a vehicle location in a navigation system, comprising the steps of:

extracting, by a control unit, an azimuth of a road on which a vehicle currently travels from a digital map data, and extracting a traveled distance per unit time of the vehicle using the number of pulse signals output from an odometer of a sensor unit according to travel of the vehicle;

estimating current longitude and latitude coordinates of the vehicle using the extracted azimuth of the road, the extracted traveled distance per unit time of the vehicle, and just previously estimated longitude and latitude coordinates of the vehicle;

determining a location and a road where the vehicle will be matched on the digital map using the extracted-azimuth of the road and the estimated longitude and latitude coordinates of the vehicle; and

matching the vehicle at the determined location and road and displaying the matched results.

31. A method for detecting a vehicle location in a navigation system, comprising the steps of:

acquiring, by a control unit, a current vehicle location using hybrid navigation;

acquiring an inclination of a road on which a vehicle travels using detection signals from a sensor unit;

searching roads within a search radius set from the acquired current vehicle location using digital map data, extracting roads on which the vehicle location will be matched, and searching attributes of the extracted roads;

if it is determined from the search results of the road attributes that there is no entrance link for an overpass, the current vehicle location is matched on a road closest thereto;

if it is determined from the search results of the road attributes that there is an entrance link for an overpass, comparing the acquired inclination of the road on which the vehicle currently travels with an inclination of a previous road on which the vehicle has traveled;

if it is determined from the comparison that the inclination of the current road is larger than that of the previous road, matching the vehicle location on an overpass; and

if it is determined from the comparison that the inclination of the current road is not larger than that of the previous road, matching the vehicle location on a closest road among roads except overpasses.