System, method and medium calibrating gyrosensors of mobile robots

• US 8,135,562 B2
• Filed: 12/06/2007
• Issued: 03/13/2012
• Est. Priority Date: 04/04/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Hyoung-Ki, Choi, Ki-Wan, Park, Ji-Young, Bang, Seok-Won, Hong, Sung-Kyung
• Primary Examiner(s): Lau, Tung S
• Application Number:
  US12/000,012
• Publication Number:
  US 20080249732A1
• Time in Patent Office: 1,559 Days
• Field of Search: 702/151
• US Class Current: 702/151
• CPC Class Codes: G01C 19/42 for indicating rate of turn; for integrating rate of turn
• CPC Class Codes: G01C 25/005 initial alignment, calibration or starting-up of inertial devices

Abstract

Provided are a system, method and medium calibrating a gyrosensor of a mobile robot. The system includes a camera to obtain image data of a fixed environment, a rotation angle calculation unit to calculate a plurality of angular velocities of a mobile robot based on an analysis of the image data, a gyrosensor to output a plurality of pieces of raw data according to rotation inertia of the mobile robot and a scale factor calculation unit to calculate a scale factor that indicates the relationship between the pieces of raw data and the angular velocities.

Claims

1. A system for calibrating a gyrosensor of a mobile robot, the system comprising:

a camera to obtain image data of a fixed environment;

a rotation angle calculation unit to calculate a plurality of angular velocities of the mobile robot based on an analysis of the image data;

the gyrosensor to output a plurality of pieces of raw data according to rotation inertia of the mobile robot; and

a scale factor calculation unit to calculate a scale factor that indicates the relationship among raw data, a bias of the gyrosensor, and the angular velocities, in order to calibrate the gyrosensor of the mobile robot,

wherein when the mobile robot moves the bias of the gyrosensor is interpolated between bias values at two positions where the mobile robot stops.

2. The system of claim 1, wherein the fixed environment is a ceiling.

3. The system of claim 1, wherein the pieces of raw data are output voltages of the gyrosensor.

4. The system of claim 1, further comprising a motor control unit to rotate the mobile robot in a predetermined angular velocity pattern.

5. The system of claim 1, wherein the scale factor calculation unit calculates the scale factor by applying a least square method to a plurality of data pairs of the pieces of raw data and the angular velocities.

6. The system of claim 1, wherein a value input to an objective function used in the least square method, is obtained by subtracting the interpolated bias from the raw data.

7. The system of claim 5, wherein the least square method is a weighted least square (WLS) method, and the scale factor calculation unit assigns a weight to each of the data pairs.

8. The system of claim 5, wherein the scale factor is a set of coefficients of a polynomial of a predetermined order.

9. The system of claim 7, wherein a greater weight is assigned as a distance to a boundary between a mobile state and a stationary state of the mobile robot increases.

10. A system for calibrating a gyrosensor of a mobile robot, the system comprising:

a camera to obtain image data of a fixed environment;

a rotation angle calculation unit to calculate a rotation angle of the mobile robot based on an analysis of the image data;

an encoder to output encoder data according to rotation velocity of a motor;

a reference angular velocity calculation unit to calculate encoder parameters using the calculated rotation angle and encoder data corresponding to the calculated rotation angle and obtaining a plurality of reference angular velocities by applying a plurality of pieces of encoder data to the calculated encoder parameters;

the gyrosensor to output a plurality of pieces of raw data according to rotation inertia of the mobile robot; and

a scale factor calculation unit to calculate a scale factor that indicates the relationship among raw data, a bias of the gyrosensor, and the reference angular velocities, in order to calibrate the gyrosensor of the mobile robot,

wherein when the mobile robot moves the bias of the gyrosensor is interpolated between bias values at two positions where the mobile robot stops.

11. The system of claim 10, wherein the encoder parameters are coefficients when the calculated rotation angle is represented as a linear combination of respective encoder displacements of wheels of the mobile robot.

12. The system of claim 10, wherein the fixed environment is a ceiling.

13. The system of claim 10, wherein the pieces of raw data are output voltages of the gyrosensor.

14. The system of claim 10, further comprising a motor control unit to rotate the mobile robot in a predetermined angular velocity pattern.

15. The system of claim 10, wherein the scale factor calculation unit calculates the scale factor by applying least square method to a plurality of data pairs of the pieces of raw data and the reference angular velocities.

16. The system of claim 10, wherein a value input to an objective function used in the least square method, is obtained by subtracting the interpolated bias from the raw data.

17. The system of claim 15, wherein the least square method is a weighted least square (WLS) method, and the scale factor calculation unit assigns a weight to each of the data pairs.

18. The system of claim 15, wherein the scale factor is a set of coefficients of a polynomial of a predetermined order.

19. The system of claim 17, wherein a greater weight is assigned as a distance to a boundary between a mobile state and a stationary state of the mobile robot increases.