Method and system for creating indoor environment map

• US 9,310,807 B2
• Filed: 01/22/2010
• Issued: 04/12/2016
• Est. Priority Date: 07/23/2007
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Lee, Yu-Cheol, Na, Sang Ik, Yu, Won Pil, Han, Kyu Seo
• Primary Examiner(s): Tran, Khoi
• Assistant Examiner(s): MOYER, DALE S
• Application Number:
  US12/692,113
• Publication Number:
  US 20100121488A1
• Time in Patent Office: 2,272 Days
• Field of Search: 700245-264, 701408-411, 701445-454, 701/461, 701/466, 701/472, 701/495, 701498-512, 701/523, 701/527, 340998-996, 340/990, 3409951-99528, 901/1
• US Class Current: 1/1
• CPC Class Codes: G01C 21/383 Indoor data
• CPC Class Codes: G01C 21/3844 Data obtained from position sensors only, e.g. from inertial navigation
• CPC Class Codes: G01C 21/3881 Tile-based structures
• CPC Class Codes: G05D 1/0231 using optical position detecting means position-fixing by using electromagnetic waves other than radio waves, e.g. optical position detecting means G01S5/16
• CPC Class Codes: G05D 1/024 in combination with a laser lasers per se H01S
• CPC Class Codes: G05D 1/0272 comprising means for registering the travel distance, e.g. revolutions of wheels measuring distance traversed on the ground by vehicles, e.g. using odometers G01C22/00
• CPC Class Codes: G05D 1/0274 using mapping information stored in a memory device navigation using map-matching G01C21/30

Abstract

A method of creating an indoor environment map includes acquiring encoded position information by detecting revolutions of wheels when a mobile unit travels using encoders to predict a position of the mobile unit based on the encoded position information, acquiring a measured distance from the mobile unit to an object existing in a surrounding environment using the distance measuring sensor, predicting a position of the mobile unit to be moved, estimating a distance from the mobile unit to the object at the predicted position of the mobile unit, determining whether the estimated distance is matched with the measured distance, correcting the predicted position of the mobile unit to estimate a position of the mobile unit to be moved by the matching of the predicted position with the measured position, and creating the indoor environment map using the corrected position and the measured distance.

Claims

1. A system for creating an indoor environment map, comprising:

a mobile unit, having wheels to freely travel, the mobile unit having a distance measuring beam sensor and a plurality of encoders mounted to the corresponding wheels, the mobile unit acquiring encoded information by detecting revolutions of the wheels using the plurality of encoders when the mobile unit travels, the mobile unit measuring a distance from the mobile unit to an object existing in a surrounding environment using the distance measuring beam sensor when the mobile unit travels;

a position prediction unit predicting a position of the mobile unit based on the encoded information and determining whether or not to correct the position of the mobile unit by applying an extended Kalman filter; and

wherein the position of the mobile unit is corrected manually by using the measured distance when an extended Kalman filter is not applied;

map creating unit creating the indoor environment map using the corrected position of the mobile unit.

2. The system of claim 1, further comprising:

a synchronizer for synchronizing the encoded information and the measured distance.

3. The system of claim 1, comprising:

a position prediction unit for predicting a position of the mobile unit based on the encoded information, and

the position prediction unit employs an extended Kalman filter to predict the position of the mobile unit.

4. The system of claim 1, wherein the indoor environment map comprises a grid map in which the surrounding environment is divided into several grids in a form of chessboard and probability is assigned to each grid where the object exists.

5. A method of creating an indoor environment map comprising:

providing a mobile unit designed to freely travel by employing a plurality of wheels, the mobile unit having a distance measuring beam sensor and a plurality of encoders mounted to the corresponding wheels;

acquiring encoded information by detecting revolutions of the wheels using the encoders when the mobile unit travels;

measuring a distance from the mobile unit to an object existing in a surrounding environment using the distance measuring beam sensor when the mobile unit travels;

predicting a position of the mobile unit based on the encoded information and determining whether or not to correct the position of the mobile unit by applying an extended Kalman filter;

correcting the position of the mobile unit manually by using the measured distance when an extended Kalman filter is not applied; and

creating the indoor environment map using the corrected position of the mobile unit.

6. The method of claim 5, wherein said creating the indoor environment map includes coupling maps created through use of a distance from the mobile unit to the object at a k-th step and a (k+1)-th step using two points matched between the maps to create the indoor environment map.

7. The method of claim 6, wherein the position of the mobile unit at the (k+1)-th step is obtained from the position ([X_k,Y_k,θ

_k] )of mobile unit at the k-th step using following Equations

8. The method of claim 5, further comprising synchronizing the encoded information and the measured distance.

9. The method of claim 5, comprising:

predicting a position of the mobile unit based on the encoded information, and

wherein the predicted position is obtained by applying an extended Kalman filter employing a grid map based on the encoded information and the measured distance, wherein the grid map has an estimation detecting grid denoting a position of the object existing in surrounding environment.

10. The method of claim 9, wherein an estimated distance is obtained from estimation of i-th information from the distance measuring beam sensor, and a position of the estimation detecting grid, T(k), of the object detected by the i-th information is defined by Equation T (k) ={(x_ti(k), y_ti(k))},

where x_ti(k) and Y_ti(k) are an X-axis position and a Y-axis position, respectively, of the object in terms of global coordinate that is detected by the i-th information of the distance measuring beam sensor.

11. The method of claim 10, wherein, when the distance measuring beam sensor projects an i-th beam, a measurement model of the estimation detecting grid where a nearest closest object exists is defined by the Equation

h_i(X(k),T(k))=√

{square root over ((x_s(k)−

x_ti(k))²+(y_s(k)−

y_ti(k))²)}{square root over ((x_s(k)−

x_ti(k))²+(y_s(k)−

y_ti(k))²)}{square root over ((x_s(k)−

x_ti(k))²+(y_s(k)−

y_ti(k))²)}{square root over ((x_s(k)−

x_ti(k))²+(y_s(k)−

y_ti(k))²)}

where h_i(X(k),T(k)) is an estimated distance of the i-th beam from the distance measuring beam sensor;

x_s(k) and y_s(k) represent an X-position and a Y-position of the distance measuring beam sensor, respectively, in terms of the global coordinate; and

x_ti(k) and y_ti(k) are estimated X-axis and Y-axis positions of an estimated object, respectively, in terms of global coordinate.

12. The method of claim 11, wherein the i-th information estimated by using the measurement model is defined by the Equation

{circumflex over (z)}_i(k+1|k)=h_i({circumflex over (X)}(k+1|k),T(k+1))

where {circumflex over (z)}_i(k+1k) is an estimated distance of the i-th beam from the distance measuring beam sensor at a (k+1)-th predicted position of the mobile unit, {circumflex over (X)}(k+1k) is the (k+1)-th predicted position of the mobile unit at a k-th position of the mobile unit, and T(k +1) _is

a position of the object detected by the i-th information of the distance measuring beam sensor at the (k+1)-th predicted position of the mobile unit.

13. The method of claim 5, wherein the indoor environment map comprises a grid map in which the surrounding environment is divided into several grids and probability is assigned to each grid where the object exists.

14. The method of claim 5, further comprising predicting a position of the mobile unit based on the encoded information, and moving the mobile unit to a position corresponding to the measured distance to create the indoor environment map using the moved position of the mobile unit and the measured distance, when the predicted position does not matched with the measured distance.