Method of measuring pose of mobile robot and method and apparatus for measuring position of mobile robot using the same

• US 20090024353A1
• Filed: 07/17/2008
• Published: 01/22/2009
• Est. Priority Date: 07/19/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Original Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Inventors: Lee, Hyoung-Ki, Jeong, Woo-Yeon, Choi, Ki-Wan, Bang, Seok-Won, Park, Ji-Young
• Granted Patent: US 7,996,179 B2
• Time in Patent Office: Days
• US Class Current: 702/153
• CPC Class Codes: G05D 1/0891 specially adapted for land vehicles
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/30244 Camera pose
• CPC Class Codes: G06T 2207/30252 Vehicle exterior; Vicinity of vehicle
• CPC Class Codes: G06T 7/73 using feature-based methods

Abstract

A method of measuring pose of mobile robot, and method and apparatus for measuring for measuring position of mobile robot using the same are provided. The apparatus for measuring the pose of a mobile robot includes an accelerometer measuring acceleration of the mobile robot in a forward direction, a uniform-motion-determining unit determining whether the mobile robot belongs to a uniform motion section, an acceleration section, or a deceleration section, and a pose-calculating unit calculating a pitch and a roll of the mobile robot in the uniform motion section, using the relationship between the measured acceleration in the forward direction and the acceleration due to gravity.

Claims

1. An apparatus for measuring the pose of a mobile robot, comprising:

an accelerometer measuring acceleration of the mobile robot in a forward direction;

a uniform-motion-determining unit determining whether the mobile robot belongs to a uniform motion section, an acceleration section, or a deceleration section; and

a pose-calculating unit calculating a pitch and a roll of the mobile robot in the uniform motion section, using the relationship between the measured acceleration in the forward direction and the acceleration due to gravity.

2. The apparatus of claim 1, further comprising:

an encoder detecting the rotational speed of traveling wheels of the mobile robot,

wherein the uniform-motion-determining unit determines which of these sections the mobile robot belongs to, on the basis of a profile of the rotational speed.

3. The apparatus of claim 1, further comprising:

a pose-compensating unit calculating the acceleration of the mobile robot in the forward direction in a global coordinate system using the calculated pitch, roll, and acceleration in the forward direction.

4. The apparatus of claim 3, wherein the pose-compensating unit calculates the acceleration in the forward direction in the global coordinate system by multiplying the measured acceleration in the forward direction by a transform matrix based on the calculated pitch and roll,

where the transform matrix is represented by

$[\begin{array}{c}\cos \end{array}$



θ

sin 



φ

sin 



θ

cos 



φ

sin 



θ

0 cos 



φ

- sin 



φ

- sin 



θ

sin 



φ

cos 



θ

cos 



φ

cos 



θ

] ,

θ

indicates the calculated pitch, and Φ

indicates the calculated roll.

5. The apparatus of claim 1, wherein:

the pose-calculating unit calculates the pitch from arcsin (acc_x/g), and

when the calculated pitch is θ

, the pose-calculating unit calculates the roll from arcsin (acc_y/g/cos θ

),

where acc_x indicates an acceleration component in the traveling direction of the mobile robot in a local coordinate system, acc_y indicates an acceleration component in a direction vertical to the traveling direction of the mobile robot in the local coordinate system, and g indicates the acceleration due to gravity.

6. The apparatus of claim 1, wherein:

the accelerometer is mounted to a front end of the mobile robot; and

the pose-calculating unit calculates the pitch in the acceleration and deceleration sections from d/L,

where d is a lifting distance of the mobile robot, and L is the distance from the center of the mobile robot to the accelerometer.

7. An apparatus for measuring the position of a mobile robot, comprising:

an accelerometer measuring the acceleration of the mobile robot in a forward direction;

a uniform-motion-determining unit determining whether the mobile robot belongs to a uniform motion section, an acceleration section, or a deceleration section;

a pose-calculating unit calculating a pitch and a roll of the mobile robot in the uniform motion section, using the relationship between the measured acceleration in the forward direction and the acceleration due to gravity;

a camera disposed on an upper surface of the mobile robot to capture a ceiling image;

a feature-point-extracting unit extracting feature points from the captured ceiling image;

a feature-point-compensating unit compensating for the coordinates of the extracted feature point using the calculated pitch and roll; and

a position-calculating unit calculating the displacement of the mobile robot on the basis of the feature point whose coordinates are compensated.

8. The apparatus of claim 7, wherein:

the pose-calculating unit calculates the pitch from arcsin (acc_x/g); and

when the calculated pitch is θ

, the pose-calculating unit calculates the roll from arcsin (acc_y/g/cos θ

),

where acc_x indicates an acceleration component in the traveling direction of the mobile robot in a local coordinate system, acc_y indicates an acceleration component in a direction vertical to the traveling direction of the mobile robot in the local coordinate system, and g indicates the acceleration due to gravity.

9. The apparatus of claim 7, further comprising:

a pose-compensating unit calculating acceleration in the forward direction in a global coordinate system, using the calculated pitch and roll and the measured acceleration in the forward direction; and

a height-calculating unit calculating the height from the mobile robot to the compensated feature point using the moving distance obtained from the calculated acceleration in the forward direction.

10. The apparatus of claim 9, wherein the pose-compensating unit calculates the acceleration in the forward direction in the global coordinate system by multiplying the measured acceleration in the forward direction by a transform matrix based on the calculated pitch and roll,

and represented by

$[\begin{array}{c}\cos \end{array}$



θ

sin 



φ

sin 



θ

cos 



φ

sin 



θ

0 cos 



φ

- sin 



φ

- sin 



θ

sin 



φ

cosθ

cos 



φ

cos 



θ

] ,

where θ

indicates the calculated pitch, and Φ

indicates the calculated roll.

11. The apparatus of claim 9, wherein the height-calculating unit calculates the height from D*f/x,

where D indicates the moving distance of the mobile robot that is calculated from the acceleration in the forward direction, f indicates a focal distance, and x indicates the displacement of the feature point in the ceiling image captured by the camera.

12. The apparatus of claim 7, wherein the position-calculating unit calculates the displacement of the mobile robot from H*f/x,

where H indicates the height of the feature point, f indicates a focal distance, and x indicates the displacement of the feature point in the ceiling image captured by the camera.

13. The apparatus of claim 7, wherein the feature-point-compensating unit compensates for the coordinates by multiplying the coordinates of the extracted feature point by a transform matrix:

$\left[\begin{array}{ccc}\cos <br><br><br><br>\mathrm{\theta <br><br>}<br><br><br><br>\cos <br><br><br><br>\mathrm{\psi <br><br>}& -\cos <br><br><br><br>\mathrm{\phi <br><br>sin\psi <br><br>}+\sin <br><br><br><br>\mathrm{\phi <br><br>sin\theta <br><br>cos}<br><br><br><br>\mathrm{\psi <br><br>}& \sin <br><br><br><br>\mathrm{\phi <br><br>sin\psi <br><br>}+\cos <br><br><br><br>\mathrm{\phi <br><br>sin}<br><br><br><br>\mathrm{\theta <br><br>cos\psi <br><br>}\\ \cos <br><br><br><br>\mathrm{\theta <br><br>sin\psi <br><br>}& \cos <br><br><br><br>\mathrm{\phi <br><br>cos\psi <br><br>}+\sin <br><br><br><br>\mathrm{\phi <br><br>sin\theta <br><br>sin\psi <br><br>}& -\sin <br><br><br><br>\mathrm{\phi <br><br>cos\psi <br><br>}+\cos <br><br><br><br>\mathrm{\phi <br><br>sin\theta <br><br>sin\psi <br><br>}\\ -\sin <br><br><br><br>\mathrm{\theta <br><br>}& \sin <br><br><br><br>\mathrm{\phi <br><br>cos\theta <br><br>}& \cos <br><br><br><br>\mathrm{\phi <br><br>cos}<br><br><br><br>\mathrm{\theta <br><br>}\end{array}\right].$

where θ and

Φ

respectively indicate the pitch and the roll calculated by the pose-calculating unit, and ψ

indicates a yaw calculated by a yaw gyrosensor.

14. A method of measuring the pose of a mobile robot, comprising:

measuring acceleration of the mobile robot in a forward direction using an accelerometer;

determining whether the mobile robot belongs to a uniform motion section, an acceleration section, or a deceleration section; and

calculating a pitch and a roll of the mobile robot in the uniform motion section, using the relationship between the measured acceleration in the forward direction and the acceleration due to gravity.

15. The method of claim 14, further comprising:

detecting the rotational speed of traveling wheels of the mobile robot,

wherein the determining of the section of the mobile robot is performed on the basis of a profile of the rotational speed.

16. The method of claim 14, further comprising:

calculating the acceleration of the mobile robot in the forward direction in a global coordinate system using the calculated pitch and roll and the measured acceleration in the forward direction.

17. The method of claim 14, wherein the calculating of the pitch and the roll comprises:

calculating the pitch from arcsin (acc_x/g); and

when the calculated pitch is θ

, calculating the roll from arcsin (acc_y/g/cos θ

),

where acc_x indicates an acceleration component in the traveling direction of the mobile robot in a local coordinate system, acc_y indicates an acceleration component in a direction vertical to the traveling direction of the mobile robot in the local coordinate system, and g indicates the acceleration due to gravity.

18. A method of measuring the position of a mobile robot, comprising:

measuring acceleration of the mobile robot in a forward direction using an accelerometer;

determining whether the mobile robot belongs to a uniform motion section, an acceleration section, or a deceleration section;

calculating a pitch and a roll of the mobile robot in the uniform motion section, using the relationship between the measured acceleration in the forward direction and the acceleration due to gravity;

capturing a ceiling image;

extracting feature points from the captured ceiling image;

compensating for the coordinates of the extracted feature point using the calculated pitch and roll; and

calculating the displacement of the mobile robot on the basis of the feature point whose coordinates have been compensated.

19. The method of claim 18, further comprising:

calculating acceleration in the forward direction in a global coordinate system, using the calculated pitch and roll and the measured acceleration in the forward direction; and

calculating the height from the mobile robot to the compensated feature point using the moving distance obtained from the calculated acceleration in the forward direction.

20. The method of claim 19, wherein the calculating of the height comprises:

calculating the height from D*f/x,

where D indicates the moving distance of the mobile robot that is calculated from the acceleration in the forward direction, f indicates a focal distance, and x indicates the displacement of the feature point in the ceiling image captured by the camera.

21. The method of claim 18, wherein the calculating of the displacement comprises:

calculating the displacement of the mobile robot from H*f/x,

where H indicates the height of the feature point, f indicates a focal distance, and x indicates the displacement of the feature point in the ceiling image captured by the camera.