Position calculation system for mobile robot and charging-stand return and method using the same

• US 20060238159A1
• Filed: 12/28/2005
• Published: 10/26/2006
• Est. Priority Date: 04/25/2005
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Jung, II-kyun
• Granted Patent: US 7,166,983 B2
• Time in Patent Office: Days
• US Class Current: 318/587
• CPC Class Codes: G05D 1/0225 involving docking at a fixed facility, e.g. base station or loading bay parking aids B62D15/027
• 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
• CPC Class Codes: G05D 1/0282 generated in a local control room

Abstract

Disclosed herein is a mobile robot which is capable of accurately calculating a position of the wireless signal source using a wireless signal, and allowing the mobile robot to accurately and rapidly return to a charging-stand using the calculated position. The position calculation system for a mobile robot includes: a wireless signal source for outputting a wireless signal continuously or periodically; and a mobile robot which includes a plurality of directional antennas for detecting the wireless signal outputted through the wireless signal source, wherein, the mobile robot calculates a direction of the wireless signal source via a rotation angle detected by the directional antennas, and calculates a distance separated from the wireless signal source using a wireless signal detection time difference between the directional antennas.

Claims

1. A position calculation system for a mobile robot comprising:

a wireless signal source for outputting a wireless signal continuously or periodically; and

a mobile robot which includes a plurality of directional antennas for detecting the wireless signal outputted through the wireless signal source, wherein, the mobile robot calculates a direction of the wireless signal source via a rotation angle detected by the directional antennas, and calculates a distance separated from the wireless signal source using a wireless signal detection time difference between the directional antennas.

2. The position calculation system as set forth in claim 1, wherein the mobile robot comprises:

a driving unit, which includes a left-wheel motor and a right-wheel motor, for running the mobile robot;

a memory for storing an operating program of the mobile robot, and storing distance information and direction information with respect to the mobile robot; and

a microprocessor for controlling running of the mobile robot, calculating position information of the mobile robot and controlling overall components of the mobile robot.

3. The position calculation system as set forth in claim 2, wherein the memory comprises:

a distance information mapping table for mapping the distance information according to the wireless signal detection time difference between the directional antennas; and

a position information database for storing the distance information and direction information with respect to the mobile robot separated from the wireless signal source.

4. The position calculation system as set forth in claim 3, wherein the microprocessor comprises:

a running control unit for controlling running of the driving unit on the basis of a control signal; and

a position information calculating unit for calculating the distance information and direction information with respect to the mobile robot, and storing the calculated distance information and direction information in the position information database.

5. The position calculation system as set forth in claim 4, wherein the position information calculating unit outputs the control signal to the running control unit in order to rotate the mobile robot at a predetermined velocity for each time interval, wherein, the position information calculating unit calculates the direction information on the basis of a rotation angle of the wireless signal which is detected by the directional antenna, and stores the calculated directional information in the position information database.

6. The position calculation system as set forth in claim 4, wherein the position information calculating unit calculates the distance information by accessing to the distance information mapping table so as to acquire the distance information corresponding to the detection time difference of the wireless signals outputted through the directional antennas, and stores the calculated distance information in the position information database.

7. The position calculation system as set forth in claim 1, wherein the wireless signal source is a charging-stand for the mobile robot.

8. A system for returning a mobile robot to a charging-stand, the system comprising:

a charging-stand for outputting a wireless signal continuously or periodically; and

a mobile robot which includes at least two directional antennas for detecting the wireless signal outputted through the charging-stand, wherein, when a power level remaining in a battery of the mobile robot is below a predetermined value, the mobile robot calculates distance information with respect to the mobile robot separated from the charging-stand using a direction of the charging-stand detected by the directional antennas and using a wireless signal detection time difference between the directional antennas, and returns to the charging-stand on the basis of the distance information.

9. The system as set forth in claim 8, wherein the mobile robot comprises:

a driving unit including a left-wheel motor and a right-wheel motor for running the mobile robot;

a battery voltage detection circuit for detecting a battery voltage of the mobile robot at a predetermined time interval, and outputting a charging request signal when the detected battery voltage is below a reference value;

a memory for storing an operating program of the mobile robot, and storing distance information between the charging-stand and the mobile robot; and

a microprocessor for controlling a running of the mobile robot, calculating a direction of the charging-stand, calculating information for a distance separated from the charging-stand, and controlling overall components of the mobile robot.

10. The system as set forth in claim 9, wherein the memory comprises a distance information mapping table for mapping the distance information between the charging-stand and the mobile robot according to the wireless signal detection time difference between the directional antennas.

11. The system as set forth in claim 10, wherein the microprocessor comprises:

a running control unit for controlling running of the driving unit on the basis of a control signal;

a position information calculating unit for calculating the distance information and direction information with respect to the mobile robot which is separated from the charging-stand, and outputting the calculated distance information and direction information; and

a charging-stand return processing unit for allowing the mobile robot to return to the charging-stand on the basis of the calculated distance information and direction information outputted through the position information calculating unit.

12. The system as set forth in claim 11, wherein the position information calculating unit outputs the control signal to the running control unit in order to rotate the mobile robot at a predetermined velocity for each time interval when a charging request signal is received, wherein, the position information calculating unit calculates the direction information on the basis of a rotation angle of the wireless signal which is detected by the directional antenna.

13. The system as set forth in claim 11, wherein the position information calculating unit outputs the distance information by accessing to the distance information mapping table so as to acquire the distance information corresponding to the detection time difference of the wireless signals outputted through the directional antennas.

14. The system as set forth in claim 11, wherein the charging-stand return processing unit outputs the control signal to the running control unit in order to return the mobile robot to the charging-stand using the direction information and distance information calculated through the position information calculating unit.

15. A method for returning a mobile robot to a charging-stand, in which the mobile robot includes a position information calculating unit and a charging-stand return processing unit, the method comprising the steps of:

a) detecting a wireless signal using a directional antenna, wherein the wireless signal is outputted from the charging-stand;

b) calculating direction information of the charging-stand and distance information between the charging-stand and the mobile robot, and outputting the calculated direction information and distance information, wherein the position information calculating unit calculates the direction information and distance information using the detected wireless signal; and

c) returning the mobile robot to the charging-stand, wherein the charging-stand return processing unit allows the mobile robot to return to the charging-stand on the basis of the direction information and distance information outputted through the position information calculating unit.

16. The method as set forth in claim 15, further comprising the step of:

detecting a battery voltage of the mobile robot at a predetermined time interval, and outputting a charging request signal when the detected battery voltage is below a reference value prior to performing Step a).

17. The method as set forth in claim 16, wherein said step a) comprises outputting a control signal to a running control unit in order to rotate the mobile robot at a predetermined velocity for each time interval when the charging request signal is received.

18. The method as set forth in claim 15, wherein said step b) comprises calculating the directional information and the calculated directional information, wherein the position information calculating unit calculates the direction information on the basis of a rotation angle of the wireless signal which is detected by the directional antenna.

19. The method as set forth in claim 15, wherein said step b) comprises calculating the distance information and outputting the calculated distance information, wherein the position information calculating unit outputs the distance information by accessing to a distance information mapping table so as to acquire the distance information corresponding to the detection time difference of the wireless signals outputted through at least two directional antennas.

20. The method as set forth in claim 15, wherein said step c) comprises outputting a control signal to a running control unit in order to return the mobile robot to the charging-stand using the direction information and distance information calculated through the position information calculating unit.