System, method and medium calibrating gyrosensors of mobile robots

• US 20080249732A1
• Filed: 12/06/2007
• Published: 10/09/2008
• 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, Bang, Seok-Won, Park, Ji-Young, Hong, Sung-Kyung
• Granted Patent: US 8,135,562 B2
• Time in Patent Office: Days
• US Class Current: 702/96
• 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 between the pieces of raw data and the angular velocities.

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 (LS) method to a plurality of data pairs of the pieces of raw data and the angular velocities.

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

7. The system of claim 6, 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.

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 5, wherein, based on raw data measured when the mobile robot is not moving, the scale factor calculation unit interpolates a bias of the gyrosensor while the mobile robot is rotating.

10. The system of claim 9, wherein a value input to an objective function used in the LS method, is obtained by subtracting the interpolated bias from the raw data.

11. 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 between the pieces of raw data and the reference angular velocities.

12. The system of claim 11, 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.

13. The system of claim 11, wherein the fixed environment is a ceiling.

14. The system of claim 11, wherein the pieces of raw data are output voltages of the gyrosensor.

15. The system of claim 11, further comprising a motor control unit to rotate the mobile robot in a predetermined angular velocity pattern.

16. The system of claim 11, wherein the scale factor calculation unit calculates the scale factor by applying an LS method to a plurality of data pairs of the pieces of raw data and the reference angular velocities.

17. The system of claim 16, wherein the LS method is a WLS method, and the scale factor calculation unit assigns a weight to each of the data pairs.

18. 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.

19. The system of claim 16, wherein the scale factor is a set of coefficients of a polynomial of a predetermined order.

20. The system of claim 16, wherein, based on raw data measured when the mobile robot is not moving, the scale factor calculation unit interpolates a bias of the gyrosensor while the mobile robot is rotating.

21. The system of claim 20, wherein a value input to an objective function used in the LS method, is obtained by subtracting the interpolated bias from the raw data.

22. A method of calibrating a gyrosensor of a mobile robot, the method comprising:

obtaining image data of a fixed environment;

calculating a plurality of angular velocities of the mobile robot based on an analysis of the image data; and

calculating a scale factor that indicates the relationship between a plurality of pieces of raw data according to rotation inertia of the mobile robot and the angular velocities.

24. At least one medium comprising computer readable code to control at least one processing element in a computer to implement the method of claim 22.

23. A method of calibrating a gyrosensor of a mobile robot, the method comprising:

obtaining image data of a fixed environment;

calculating a rotation angle of the mobile robot based on an analysis of the image data;

calculating encoder parameters using the calculated rotation angle and encoder data corresponding to the calculated rotation angle;

obtaining a plurality of reference angular velocities by applying a plurality of pieces of encoder data to the calculated encoder parameters; and

calculating a scale factor that indicates the relationship between a plurality of pieces of raw data according to rotation inertia of the mobile robot and the reference angular velocities.

25. At least one medium comprising computer readable code to control at least one processing element in a computer to implement the method of claim 23.

26. A method of calibrating a gyrosensor of a mobile robot, the method comprising:

rotating the mobile robot in a predetermined velocity pattern;

capturing image data at a predetermined location as the mobile robot rotates;

estimating kinematic parameters of the mobile robot based on the captured image data;

calculating a plurality of reference angular velocities in real time by applying real-time encoder data to the estimated kinematic parameters and continuously providing the calculated reference angular velocities; and

calibrating the gyrosensor based on the continuously provided reference angular velocities.

27. At least one medium comprising computer readable code to control at least one processing element in a computer to implement the method of claim 26.