Method and apparatus for generating magnetic field map and method and apparatus for checking pose of mobile body using the magnetic field map

• US 7,302,345 B2
• Filed: 01/18/2005
• Issued: 11/27/2007
• Est. Priority Date: 02/04/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kwon, Woong, Roh, Kyung-shik, Han, Woo-sup, Shim, Young-bo
• Primary Examiner(s): Barlow; John
• Assistant Examiner(s): Le; Toan M.
• Application Number:
  US11/035,742
• Publication Number:
  US 20050194973A1
• Time in Patent Office: 1,043 Days
• Field of Search: 702/5, 324/200, 324/260, 700/245, 701/1, 701/25, 333/55.R, 318/568.12, 901/1, 901/8
• US Class Current: 702/5
• CPC Class Codes: G01R 33/10 Plotting field distribution ; Measuring field distribution
• CPC Class Codes: G05D 1/0259 using magnetic or electromagnetic means
• CPC Class Codes: G05D 1/0274 using mapping information stored in a memory device navigation using map-matching G01C21/30

Abstract

Provided is a method of generating a magnetic field map including obtaining magnetic field information, the magnetic field information being information on a magnetic field affecting a mobile body, for each position of the mobile body, and building a magnetic field map based on the magnetic field information for each position of the mobile body. The pose of a mobile body can be statistically checked by the probability obtained using the difference between the magnetic field information observed from the magnetic field map and the actually measured magnetic field information. Although the pose of the mobile body is estimated using a camera that is sensitive to an illumination state where the mobile body is placed, the pose of the mobile body can be relatively accurately checked using the magnetic field map obtained in a situation regardless of illumination, with being less affected by the illumination state where the mobile body is placed. Thus, the pose of the mobile body can be checked with reliability.

Claims

1. A method of generating a magnetic field map, comprising:

obtaining magnetic field information, the magnetic field information being information on a magnetic field affecting a mobile body, for each position of the mobile body;

building the magnetic field map based on the magnetic field information for each position of the mobile body; and

outputting the magnetic field map,

wherein the obtaining of the magnetic field information comprises;

recognizing a present position of the mobile body;

obtaining the magnetic field information at the recognized present position, matching the obtained magnetic field information and the present position, and storing a matching result;

determining whether the magnetic field information is obtained for all positions on the magnetic field map and, if it is determined that the magnetic field information is obtained with respect to all positions, proceeding to the building of the magnetic field map; and

if it is determined that the magnetic field information is not obtained with respect to all positions, adjusting the present position such that a next target position becomes the present position and proceeding to the recognizing of the present position of the mobile body,

wherein, in the recognizing of the present position of the mobile body, the next target position is recognized as the present position after adjusting the present position such that the next target position becomes the present position.

2. The method as claimed in claim 1, wherein, in recognizing the present position of the mobile body, the present position of the mobile body is estimated and the estimated present position is recognized.

3. The method as claimed in claim 1, wherein, in recognizing the present position of the mobile body, the present position of the mobile body is given in advance and the given present position is recognized.

4. The method as claimed in claim 1, wherein the next target position is determined by an active Markov location method.

5. The method as claimed in claim 1, wherein the next target position is determined by a partially observable Markov decision process.

6. A method of generating a magnetic field map, comprising:

obtaining magnetic field information, the magnetic field information being information on a magnetic field affecting a mobile body, for each position of the mobile body;

building the magnetic field map based on the magnetic field information for each position of the mobile body; and

outputting the magnetic field map,

wherein the obtaining of the magnetic field information comprises;

recognizing each of all positions on the magnetic field map; and

obtaining the magnetic field information at each of the recognized positions, matching the obtained magnetic field information with the recognized position and storing a matching result, and proceeding to the building of the magnetic field map.

7. A method of generating a magnetic field map, comprising:

obtaining magnetic field information, the magnetic field information being information on a magnetic field affecting a mobile body, for each position of the mobile body;

building the magnetic field map based on the magnetic field information for each position of the mobile body; and

outputting the magnetic field map,

wherein the obtaining of the magnetic field information comprises;

recognizing a present position of the mobile body;

obtaining and storing the magnetic field information at the present recognized position;

determining whether a preceding position being recognized just before the present position is recognized and the present position exist in a same cell;

if it is determined that the present position and the preceding position exist in the same cell, moving the mobile body to a next target position and proceeding to the recognizing of the present position of the mobile body;

if it is determined that the present position and the preceding position do not exist in the same cell, determining a representative value of the magnetic field information of positions belonging to a cell to which the preceding position belongs; and

determining whether the representative values are obtained with respect to all cells on the magnetic field map and, if it is determined that the representative values are obtained with respect to all cells, proceeding to the building of the magnetic field map, and if it is determined that representative values are not obtained with respect to all cells, proceeding to the moving of the mobile body to the next target position,

wherein each cell includes one or more positions the magnetic field map is built based on the representative value for each cell, and, after moving the mobile body to the next target position, the next target position is regarded as the present position.

8. The method as claimed in claim 7, wherein the representative value of each cell corresponds to an average of the magnetic field information of the positions included in each cell.

9. The method as claimed in claim 7, wherein, when the magnetic field information is divided into a plurality of sections, the representative value is a corresponding section.

10. A method of generating a magnetic field map, comprising:

obtaining magnetic field information, the magnetic field information being information on a magnetic field affecting a mobile body, for each position of the mobile body;

building the magnetic field map based on the magnetic field information for each position of the mobile body; and

outputting the magnetic field map,

wherein the obtaining of the magnetic field information comprises;

recognizing present positions of mobile bodies, the mobile bodies existing as many as a number of cells included in the magnetic filed map;

obtaining and storing the magnetic field information at each of the present recognized positions;

determining whether a preceding position, the preceding position being recognized just before the present position is recognized, and the present position exist in a same cell;

if it is determined that the present position and the preceding position exist in the same cell, adjusting the present position such that a next target position of each mobile body becomes the present position and proceeding to the recognizing of the present positions of mobile bodies; and

if it is determined that the present position and the preceding position do not exist in the same cell, determining a representative value of the magnetic field information of positions belonging to a cell to which the preceding position belongs and proceeding to the building of the magnetic field map,

wherein each cell includes one or more positions, the magnetic field map is built based on the representative value for each cell, and, after adjusting the present position such that the next target position of each mobile body becomes the present position, the next target position is regarded as the present position.

11. A method of generating a magnetic field map, comprising:

obtaining magnetic field information, the magnetic field information being information on a magnetic field affecting a mobile body, for each position of the mobile body;

building the magnetic field map based on the magnetic field information for each position of the mobile body; and

outputting the magnetic field map,

wherein the magnetic field information includes at least one of a magnitude of the magnetic field and a direction of a magnetic north.

12. A method of checking pose of a mobile body using a magnetic field map, comprising:

obtaining magnetic field information, the magnetic field information being information on a magnetic field affecting a mobile body, for each position of the mobile body;

building the magnetic field map based on the magnetic field information for each position of the mobile body;

after building the magnetic field map, estimating a position of the mobile body;

obtaining a probability of pose of the mobile body existing at the estimated position;

adjusting the probability using both the magnetic field information expected at the estimated position on the magnetic field map and the magnetic field information actually measured at the estimated position; and

outputting the adiusted probability,

wherein the probability of the pose corresponds to at least one of a probability of the mobile body existing at the estimated position and a probability of the mobile body having an estimated direction, the pose of the mobile body is checked through the adjusted probability.

13. The method as claimed in claim 12, wherein at least one of the estimating of the position of the mobile body and the obtaining of the probability of pose of the mobile body at the estimated position is performed using a Kalman filer.

14. The method as claimed in claim 12, wherein at least one of the estimating of the position of the mobile body and the obtaining of the probability of pose of the mobile body at the estimated position is performed using a Markov localization method.

15. The method as claimed in claim 12, wherein at least one of the estimating of the position of the mobile body and the obtaining of the probability of pose of the mobile body at the estimated position is performed using a particle filter.

16. The method as claimed in claim 12, wherein at least one of the estimating of the position of the mobile body and the obtaining of the probability of pose of the mobile body at the estimated position is performed using a multiple hypothesis localization method.

17. The method as claimed in claim 12, wherein the magnetic field information is at least one of a magnitude of the magnetic field and a direction of a magnetic north.

18. The method as claimed in claim 12, wherein the adjusting of the probability comprises:

obtaining an absolute value of a difference between the expected magnetic field information and the measured magnetic field information;

summing the absolute value of the difference and a first predetermined number;

dividing a second predetermined number by the summing result; and

multiplying the division result and the probability and determining a multiplication result as the adjusted probability,

wherein the first predetermined number is preset such that the summing result becomes a positive number.

19. An apparatus for generating a magnetic field map, comprising:

a magnetic field information calculation portion calculating magnetic field information, the magnetic filed information being information on a magnetic field affecting a mobile body, for each position of the mobile body; and

a magnetic field map building portion building the magnetic field map based on the magnetic field information for each position of the mobile body output from the magnetic field information calculation portion,

wherein the magnetic field information calculation portion comprises;

a position recognition portion recognizing a present position of the mobile body;

a magnetic field information portion calculating the magnetic field information at the present position recognized by the position recognition portion, matching the present position and the calculated magnetic field information, and storing a matching result;

a magnetic field information checking portion checking whether the magnetic field information is obtained with respect to all positions on the magnetic field map and outputting a check result; and

a position adjustment portion adjusting the present position such that a next target position becomes the present position and outputting an adjusted position to the position recognition portion, in response to the checking result of the magnetic filed information checking portion,

wherein the position recognition portion recognizes the next target position adjusted by the position adjustment portion as the present position, and the magnetic field map building portion builds the magnetic field map in response to the checking result of the magnetic field information checking portion.

20. An apparatus for generating a magnetic field map, comprising:

a magnetic field information calculation portion calculating magnetic field information, the magnetic filed information being information on a magnetic field affecting a mobile body, for each position of the mobile body; and

a magnetic field map building portion building the magnetic field map based on the magnetic field information for each position of the mobile body output from the magnetic field information calculation portion,

wherein the magnetic field information calculation portion comprises;

first through M^th position recognition portions recognizing each of all positions on the magnetic field map, wherein M denotes the number of all positions; and

first through M^th magnetic field information portions,

wherein m^th magnetic field information portion calculates the magnetic field information at the position recognized by m^th position recognition portion, in which 1≦

m≦

M, and the calculated magnetic field information is matched with the recognized position and a matching result is stored.

21. An apparatus for generating a magnetic field map, comprising:

a magnetic field information calculation portion calculating magnetic field information, the magnetic filed information being information on a magnetic field affecting a mobile body, for each position of the mobile body; and

a magnetic field map building portion building the magnetic field map based on the magnetic field information for each position of the mobile body output from the magnetic field information calculation portion,

wherein the magnetic field information calculation portion comprises;

a position recognition portion recognizing a present position of the mobile body;

a magnetic field information portion calculating the magnetic field information at the present position recognized by the position recognition portion and storing the calculated magnetic field information;

a position checking portion determining whether a preceding position, the preceding position being recognized just before the present position is recognized, and the present position exist in the same cell, and outputting a checking result;

a position adjustment portion adjusting the present position such that a next target position becomes the present position and outputting an adjusted position to the position recognition portion, in response to the checking result of the position checking portion;

a representative value determination portion determining a representative value of the magnetic field information of positions belonging to a cell to which the preceding position belongs, using the stored magnetic field information, in response to the checking result of the position checking portion; and

a cell checking portion checking whether the representative values are obtained with respect to all cells on the magnetic field map and outputting a checking result,

wherein each cell includes one or more positions, the position adjustment portion adjusts the present position in response to the checking result of the cell checking portion, the magnetic field map building portion builds the magnetic field map based on the representative value for each cell in response to the checking result of the cell checking portion, and the position recognition portion recognizes the next target position adjusted by the position adjustment portion as the present position.

22. An apparatus for generating a magnetic field map, comprising:

a magnetic field information calculation portion calculating magnetic field information, the magnetic filed information being information on a magnetic field affecting a mobile body, for each position of the mobile body; and

a magnetic field map building portion building the magnetic field map based on the magnetic field information for each position of the mobile body output from the magnetic field information calculation portion,

wherein the magnetic field information calculation portion comprises;

first through N^th position recognition portions recognizing present positions of N mobile bodies, wherein N denotes the number of all cells;

first through N^th magnetic field information portions;

first through N^th position checking portions;

first through N^th position adjustment portions; and

first through N^th representative value determination portions,

wherein an n^th magnetic field information portion calculates the magnetic field information at the present position recognized by an n^th position recognition portion and stores the calculated magnetic field information, in which 1≦

n≦

N,

an n^th position checking portion checks whether a preceding position, the preceding position being recognized just before the present position is recognized, and the present position exist in the same cell,

an n^th position adjustment portion adjusts the present position such that a next target position becomes the present position and outputs an adjusted position to an n^th position recognition portion, in response to the checking result of the n^th position checking portion,

an n^th representative value determination portion determines a representative value of magnetic field information of positions belonging to a cell to which the preceding position belongs, using the magnetic field information stored in an n^th magnetic field information portion, in response to the checking result of the n^th position checking portion,

wherein each cell includes one or more positions, the magnetic field map building portion builds the magnetic field map based on the representative value for each cell, and the n^th position recognition portion recognizes the next target position adjusted by the n^th position adjustment portion as the present position.

23. An apparatus for checking a pose of a mobile body, comprising:

a magnetic field information calculation portion calculating magnetic field information, the magnetic filed information being information on a magnetic field affecting a mobile body, for each position of the mobile body;

a magnetic field map building portion building the magnetic field map based on the magnetic field information for each position of the mobile body output from the magnetic field information calculation portion;

a position estimation portion estimating a position of the mobile body;

a probability calculation portion calculating a probability of the pose of the mobile body existing at the estimated position;

a magnetic field information measurement portion measuring the magnetic field information at the estimated position; and

a probability adjustment portion adjusting the probability using magnetic field information expected at the estimated position on the magnetic field map and actually measured magnetic field information output from the magnetic field information measurement portion,

wherein the probability of pose corresponds to at least one of a probability of the mobile body existing at the estimated position and a probability of the mobile body having an estimated direction, and the pose of the mobile body is checked through the adjusted probability.

24. The apparatus as claimed in claim 23, wherein the probability adjustment portion comprises:

a difference and absolute value calculation portion calculating an absolute value of a difference between the observed magnetic field information and the measured magnetic field information;

a sum portion summing the absolute value of the difference and a first predetermined number;

a division portion dividing a second predetermined number by a summing result; and

a multiplication portion multiplying a division result with the probability and outputting a multiplication result as the adjusted probability,

wherein the first predetermined number is preset such that the summing result of the sum portion becomes a positive number.

25. The apparatus as claimed in claim 23, wherein the position estimation portion includes a camera, an ultrasonic sensor, a gyro sensor, an odometer, a laser scanner, or an infrared scanner which estimates the position of the mobile body.