LOCATION MEASUREMENT METHOD BASED ON PREDICTIVE FILTER

• US 20090227266A1
• Filed: 03/04/2009
• Published: 09/10/2009
• Est. Priority Date: 03/04/2008
• Status: Active Grant

• Current Assignee: Information & Communications University, Samsung Electronics Co. Ltd.
• Original Assignee: Information & Communications University, Samsung Electronics Co. Ltd.
• Inventors: Chol, Sung-Chang, Ji, Myoung-In, Ma, Joong-Soo, Seo, Myoung-Hwan, BAIK, Jin-Serk, Oh, Yun-Je, Kim, Joon-Oo
• Granted Patent: US 8,374,624 B2
• Time in Patent Office: Days
• US Class Current: 455/456.100
• CPC Class Codes: G01S 5/0294 Trajectory determination or predictive filtering, e.g. target tracking or Kalman filtering

Abstract

Provided is a location measurement method of a mobile node using a predictive filter is provided for improving the location measurement accuracy of the mobile node. The location measurement method of a mobile node detects change of movement pattern of the mobile node, corrects weights of a location measurement period and a predictive filter depending on the change of movement pattern, and compensates a location of the mobile node using the corrected weights of the location measurement period and predictive filter.

Claims

1. A location measurement method of a mobile node, comprising:

detecting a change of a movement pattern of the mobile node;

correcting weights of a location measurement period and a predictive filter according to the change of movement pattern; and

calculating a current location of the mobile node using values updated by the corrected weights.

2. The location measurement method of claim 1, wherein detecting the change of the movement pattern of the mobile node comprises converting displacement information during a location change measurement period to cylindrical coordinates,

and wherein the location change measurement period is variable.

3. The location measurement method of claim 1, wherein the weights comprise at least one parameter that is applied to the location measurement period and the predictive filter for calculating the location measurement error caused by the change of movement pattern of the mobile node.

4. The location measurement method of claim 3, wherein the location measurement period is inversely proportional to a movement speed of the mobile node.

5. The location measurement method of claim 1, wherein correcting the weights of the location measurement period and the predictive filter comprises:

calculating displacements of a movement direction and a distance of the mobile node at every location measurement period;

comparing the calculated displacements with predetermined threshold values; and

adjusting, when the displacements are greater than respective threshold values of the predetermined threshold values, the weights to be applied to estimation values of the predictive filter.

6. The location measurement method of claim 5, wherein correcting the weights of the location measurement period and the predictive filter comprises calculating, when the displacements are less than or equal to the respective threshold values, the location measurement error by applying the adjusted weights.

7. A location measurement method of a mobile node, comprising:

estimating, when detecting a change of a movement pattern of the mobile node, a location of the mobile node using a least square method;

comparing a distance and an azimuth of the movement pattern with respective threshold values;

correcting, when the distance of the movement pattern is greater than the threshold values, a weight of a location measurement period;

correcting, when the azimuth of the movement pattern is greater than the threshold values, a weight of a predictive filter; and

calculating a location measurement of the mobile node by applying the corrected weights.

8. The location measurement method of claim 7, wherein estimating the location comprises converting displacement information to cylindrical coordinates according to a location change measurement period in order to detect the change of movement pattern of the mobile node,

and wherein the location change measurement period being variable.

9. The location measurement method of claim 7, wherein converting the displacement information to the cylindrical coordinates comprises:

calculating a displacement between the estimated location and previous location before the location change measurement period;

converting the displacement to the cylindrical coordinates; and

acquiring the distance and the azimuth of the movement pattern from the cylindrical coordinates.

10. The location measurement method of claim 7, wherein calculating the location measurement comprises:

calculating, when at least one of the distance and azimuth of the movement pattern is less than or equal to the respective threshold values, the at least one of the distance and the azimuth using the predictive filter; and

correcting, when at least one of the distance and the azimuth of the movement pattern is greater than the respective threshold values, the weight of the at least one of the distance and azimuth.

11. The location measurement method of claim 9, wherein the distance and the azimuth are obtained by calculating a displacement between location recognition coordinates ({tilde over (x)},{tilde over (y)}) measured at a time (t) and the coordinates measured and compensated before a location change measurement period (Δ

s) and converting the displacement to cylindrical coordinates using;

12. The location measurement method of claim 11, wherein location recognition coordinates ({tilde over (x)},{tilde over (y)}) are coordinates of the mobile node that are measured currently, and the location change measurement period (Δ

s) is a unit duration for measuring change of mobile node'"'"'s movement.

13. The location measurement method of claim 7, wherein the threshold values correspond to measurement error ranges of the mobile node.

14. The location measurement method of claim 7, wherein the predictive filter is a Kalman filter.