Method and apparatus for detecting position of mobile robot

• US 20050021178A1
• Filed: 12/23/2003
• Published: 01/27/2005
• Est. Priority Date: 07/23/2003
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Park, Sung-Il, Kim, Se-Wan
• Granted Patent: US 7,286,902 B2
• Time in Patent Office: Days
• US Class Current: 700/245
• CPC Class Codes: G01S 11/16 using difference in transit time between electrical and acoustic signals

Abstract

A method and apparatus for accurately and precisely detecting a position of a mobile robot are disclosed in which infrared signals having different specific frequency values according to rotational angles, an angle is determined by receiving the generated infrared signals, and a distance is calculated on the basis of a time taken for receiving a ultrasonic signal after being oscillated. The method for detecting a position of a mobile robot includes: a step in which a mobile robot receives an infrared signal generated from an infrared generator according to a rotation angle of the rotated infrared generator; a step in which an angle between the mobile robot and the infrared generator is determined on the basis of the specific frequency value of the received infrared signal and previously stored frequency values; a step in which a ultrasonic signal oscillated from a ultrasonic signal oscillator is received when the infrared generator reaches a predetermined angle; a step in which a distance between the mobile robot and the ultrasonic wave oscillator is calculated by multiplying a sound velocity to a time taken for receiving the ultrasonic signal by the mobile robot after being oscillated; and a step in which a position of the mobile robot is detected on the basis of the determined angle and the calculated distance.

Claims

1. A method for detecting a position of a mobile robot, comprising:

a step in which a mobile robot receives an infrared signal generated from an infrared generator according to a rotation angle of the rotated infrared generator;

a step in which an angle between the mobile robot and the infrared generator is determined on the basis of the specific frequency value of the received infrared signal and previously stored frequency values;

a step in which a ultrasonic signal oscillated from a ultrasonic signal oscillator is received when the infrared generator reaches a predetermined angle;

a step in which a distance between the mobile robot and the ultrasonic wave oscillator is calculated by multiplying a sound velocity to a time taken for receiving the ultrasonic signal by the mobile robot after being oscillated; and

a step in which a position of the mobile robot is detected on the basis of the determined angle and the calculated distance.

2. The method of claim 1, wherein the received infrared signals have different frequency values.

3. The method of claim 1, wherein the infrared signal generated from the infrared generator has a different frequency value whenever a rotation angle of the infrared generator is changed.

4. The method of claim 1, wherein the step of receiving the infrared signal, infrared signals having different specific frequency values generated whenever the rotation angle of the infrared generator is changed are received.

5. The method of claim 1, wherein the step of judging an angle comprises:

comparing a specific frequency value of the infrared signal generated from the infrared generator with previously stored frequency values; and

searching a frequency value identical to the specific frequency value from the comparison result, and detecting an angle corresponding to the searched frequency value.

6. The method of claim 1, wherein the predetermined value is 90 degrees.

7. The method of claim 1, wherein the infrared generator rotates by 180 degrees or 350 degrees.

8. The method of claim 1, wherein the distance (S) between the mobile robot and the ultrasonic wave oscillator is calculated by an equation of S=340 m/sec×

(T1-T2), wherein T1 is a time (seconds) taken for the ultrasonic signal to be received by the mobile robot on the basis of a time at which the infrared signal has been received by the mobile robot, and T2 is a time taken for the infrared generator to rotate up to a predetermined angle on the basis of a time at which the infrared signal has been received by the mobile robot.

9. An apparatus for detecting a position of a mobile robot, comprising:

an infrared signal generator installed in a charging unit charging a battery of a mobile robot, rotated at a predetermined angle region at a predetermined rate, and generating an infrared signal whenever the rotation angle is changed;

a ultrasonic wave oscillator installed in the charging unit and oscillating a ultrasonic signal when the infrared signal generator rotates and reaches a predetermined angle; and

a position detector for determining an angle between the mobile robot and the infrared signal generator installed in the charging unit on the basis of a frequency value of the infrared signal radiated from the infrared signal generator and previously stored reference frequency values, and calculating a distance between the mobile robot and the ultrasonic oscillator installed in the charging by multiplying a sound velocity to the ultrasonic signal oscillated from the ultrasonic wave oscillator.

10. The apparatus of claim 9, wherein the position detector comprises:

a storing unit for previously storing the reference frequency values;

an angle determining unit for comparing a specific frequency value of the infrared signal radiated from the infrared signal generator and the previously stored frequency values, searching a frequency value identical to the specific frequency value from the comparison result, and detecting an angle corresponding to the searched frequency value to determine an angle between the mobile robot and the charging unit; and

a distance calculator for calculating a distance between the mobile robot and the charging unit by multiplying a sound velocity to a difference value between a time taken for the infrared signal to be received by the mobile robot after being radiated from the infrared signal generator and a time taken for the ultrasonic signal to be received by the mobile robot after being oscillated from the ultrasonic wave oscillator.

11. The apparatus of claim 9, wherein the infrared generator generates different frequency values whenever the rotation angle is changed.

12. The apparatus of claim 9, wherein the predetermined angle is 90 degrees.

13. The apparatus of claim 9, wherein the infrared generator repeatedly rotates by 180 degrees and 360 degrees.

14. The apparatus of claim 10, wherein the distance calculator calculates the distance by equation of S=340×

(T1-T2), wherein ‘

S’

is the distance between the mobile robot and the charging unit, T1 is a time taken for the ultrasonic signal to be received by the mobile robot on the basis of a time at which the infrared signal has been received by the mobile robot, and T2 is a time taken for the infrared generator to rotate up to a predetermined angle on the basis of a time at which the infrared signal has been received by the mobile robot.

15. A charging device for charging a battery of a mobile robot comprising:

an infrared signal generator rotating a predetermined angle region at a predetermined speed and generating infrared signals having different frequency signal values whenever the rotation angle is changed; and

a ultrasonic wave oscillator for oscillating a ultrasonic signal when the infrared signal generator rotates and reaches the predetermined angle.

16. A mobile robot moving on the basis of previously stored map information comprising:

an angle determining unit for comparing an specific frequency value of an infrared signal generated from the infrared generator according to a rotation angle of the rotated infrared generator and previously stored frequency values, searching a frequency value identical to the specific frequency value, and determining an angle between the mobile robot and the infrared generator by detecting an angle corresponding to the searched frequency value; and

a distance calculator for calculating a distance between the mobile robot and the charging unit by multiplying a sound velocity to a difference value between the time taken for the infrared signal to be received by the mobile robot after being radiated from the infrared signal generator and the time taken for the ultrasonic signal to be received by the mobile robot after being oscillated from the ultrasonic wave oscillator.

17. An apparatus for detecting a position of a mobile robot, comprising:

a unit for receiving an infrared signal generated from an infrared generator according to a rotation angle of the rotated infrared generator;

a unit for determining an angle between the mobile robot and the infrared generator on the basis of an specific frequency value of the received infrared signal and previously stored frequency values;

a unit for receiving a ultrasonic signal oscillated from a ultrasonic signal oscillator when the infrared generator reaches a predetermined angle;

a unit for calculating a distance between the mobile robot and the ultrasonic oscillator by multiplying a sound velocity to a time taken for the ultrasonic signal to be received by the mobile robot after being oscillated; and

a unit for detecting a position of the mobile robot on the basis of the determined angle and the calculated distance.