Robotic work tool system and method comprising a charging station

• US 9,872,437 B2
• Filed: 02/20/2013
• Issued: 01/23/2018
• Est. Priority Date: 02/20/2013
• Status: Active Grant

• Current Assignee: Husqvarna AB (HUSQVARNA)
• Original Assignee: Husqvarna AB (HUSQVARNA)
• Inventors: Markusson, Olle, Jgenstedt, Patrik, Hallin, Peter
• Primary Examiner(s): Pelton, Nathaniel
• Assistant Examiner(s): TORRES RUIZ, JOHALI ALEJANDRA
• Application Number:
  US14/767,155
• Publication Number:
  US 20150366137A1
• Time in Patent Office: 1,798 Days
• Field of Search: 320107, 700245, 31856812
• CPC Class Codes: A01D 34/008 for automated or remotely controlled operation
• CPC Class Codes: A01D 69/02 electric
• CPC Class Codes: B60L 1/003 to auxiliary motors, e.g. for pumps, compressors
• CPC Class Codes: B60L 15/20 for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
• CPC Class Codes: B60L 2200/40 Working vehicles
• CPC Class Codes: B60L 2240/36 Temperature of vehicle components or parts
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2260/32 Auto pilot mode
• CPC Class Codes: B60L 3/0061 relating to electrical machines
• CPC Class Codes: B60L 50/52 characterised by DC-motors
• CPC Class Codes: B60L 50/66 Arrangements of batteries
• CPC Class Codes: B60L 53/16 Connectors, e.g. plugs or sockets, specially adapted for charging electric vehicles
• CPC Class Codes: B60L 8/003 Converting light into electric energy, e.g. by using photo-voltaic systems
• 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 1/0265 using buried wires
• CPC Class Codes: G05D 1/03 using near-field transmission systems, e.g. inductive-loop type G05D1/021 and subgroups take precedence
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H02J 7/0045 concerning the insertion or the connection of the batteries
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y02T 90/14 : Plug-in electric vehicles

Abstract

A robotic work tool system (200), comprising a charging station (210), a boundary wire (250), a signal generator (240) for generating and transmitting a signal through said boundary wire (250) for demarcating a work area (205) and for generating a magnetic field (265) for guiding a robotic work tool (100) to said charging station (210), said robotic work tool (100) being configured to detect a magnetic field strength of the magnetic field (265) in the work area (205), direct itself towards an increasing magnetic field strength, determine that the robotic work tool (100) is unable to reach the charging station (210), inform the robotic work tool system (200) accordingly, whereby the robotic work tool system (200) is configured to adapt a current level of the signal generating the magnetic field (365).

Claims

1. A robotic work tool system, comprising:

a robotic work tool,

a charging station,

a boundary wire, and

a signal generator configured to generate and transmit a signal through the boundary wire for demarcating a work area, and configured to generate a magnetic field for guiding the robotic work tool to the charging station, the magnetic field for guiding the robotic work tool to the charging station being generated by either a conductive loop other than the boundary wire and associated with the charging station or a cable other than the boundary wire and associated with the charging station, the robotic work tool being configured to;

detect a magnetic field strength of the magnetic field for guiding the robotic work tool to the charging station in the work area;

direct the robotic work tool towards an increasing magnetic field strength of the magnetic field for guiding the robotic work tool to the charging station;

determine that the robotic work tool is unable to reach the charging station; and

in response to determining that the robotic work tool is unable to reach the charging station, decrease a range from the charging station within which the robotic work tool operates to move towards the increasing magnetic field strength of the of the magnetic field for guiding the robotic work tool to the charging station.

2. The robotic work tool system according to claim 1, wherein the robotic work tool is further configured to decrease the range by causing the signal generator to adapt a current level to the conductive loop other than the boundary wire or the cable other than the boundary wire that generates the magnetic field for guiding the robotic work tool to the charging station.

3. The robotic work tool of claim 2, wherein the robotic work tool configured to cause the signal generator to adapt the current level includes being configured to cause the signal generator to decrease the current level to the conductive loop other than the boundary wire or the cable other than the boundary wire.

4. The robotic work tool system according to claim 1, wherein the robotic work tool is configured to decrease the range by adjusting a threshold magnetic field strength level for detecting the magnetic field generated by the conductive loop other than the boundary wire or the cable other than the boundary wire.

5. The robotic work tool of claim 4, wherein the robotic work tool configured to adjust the threshold magnetic field strength level includes being configured to increase the threshold magnetic field strength level at which the robotic work tool transitions to moving towards the increasing magnetic field strength of the magnetic field for guiding the robotic work tool to the charging station.

6. The robotic work tool system according to claim 1, wherein the the magnetic field generated by the conductive loop other than the boundary wire or the cable other than the boundary wire is manually adaptable by a user.

7. The robotic work tool system according to claim 1, wherein the magnetic field generated by the conductive loop other than the boundary wire or the cable other than the boundary wire is automatically adaptable by the robotic work tool.

8. The robotic work tool system according to claim 1, wherein the robotic work tool is configured to determine that the robotic work tool is unable to reach the charging station based on a number of times the robotic work tool collides with an object while moving towards the increasing magnetic field strength of the of the magnetic field for guiding the robotic work tool to the charging station.

9. The robotic work tool system according to claim 1, wherein the robotic work tool is configured to determine that the robotic work tool is unable to reach the charging station based on a duration of time spent to find the charging station while moving towards the increasing magnetic field strength of the of the magnetic field for guiding the robotic work tool to the charging station.

10. The robotic work tool system according to claim 1, wherein the robotic work tool configured to decrease the range includes being configured to cause the signal generator to decrease the magnetic field strength of the magnetic field generated by the conductive loop other than the boundary wire or the cable other than the boundary wire.

11. The robotic work tool system according to claim 1, wherein the robotic work tool is further configured to:

determine the robotic work tool a frequency that the robotic work tool is able to reach the charging station, and

based on the frequency, cause the signal generator to increase a magnetic field strength of the magnetic field generated by the conductive loop other than the boundary wire or the cable other than the boundary wire.

12. The robotic work tool system according to claim 1, wherein the robotic work tool is further configured to communicate during a working session and instruct the signal generator, during the working session, to dynamically adapt the magnetic field generated by the conductive loop other than the boundary wire or the cable other than the boundary wire.

13. The robotic work tool system according to claim 1, wherein robotic work tool is a robotic lawn mower.

14. A method for use in a robotic work tool system, the robotic work tool system comprising:

a robotic work tool,

a charging station,

a boundary wire, and

a signal generator configured to generate and transmit a signal through the boundary wire to demarcate a work area, and configured to generate a magnetic field for guiding the robotic work tool to the charging station, the magnetic field for guiding the robotic work tool to the charging station being generated by either a conductive loop other than the boundary wire and associated with the charging station or a cable other than the boundary wire and associated with the charging station,

the method comprising;

detecting a magnetic field strength of the magnetic field for guiding the robotic work tool to the charging station in the work area;

directing the robotic work tool towards an increasing magnetic field strength of the magnetic field for guiding the robotic work tool to the charging station;

determining that the robotic work tool is unable to reach the charging station; and

in response to determining that the robotic work tool is unable to reach the charging station, decreasing a range from the charging station within which the robotic work tool operates to move towards the increasing magnetic field strength of the of the magnetic field for guiding the robotic work tool to the charging station.

15. The method according to claim 14, wherein decreasing the range further comprises decreasing the range by causing the signal generator to adapt a current level to the conductive loop other than the boundary wire or the cable other than the boundary wire that generates the magnetic field for guiding the robotic work tool to the charging station.

16. The method of claim 15, wherein causing the signal generator to adapt the current level comprises causing the signal generator to decrease the current level to the conductive loop other than the boundary wire or the cable other than the boundary wire.

17. The method according to claim 14, wherein decreasing the range further comprises decreasing the range by adjusting a threshold magnetic field strength level for detecting the magnetic field generated by the conductive loop other than the boundary wire or the cable other than the boundary wire.

18. The method of claim 17, wherein adjusting the threshold magnetic field strength level comprises increasing the threshold magnetic field strength level at which the robotic work tool transitions to moving towards the increasing magnetic field strength of the magnetic field for guiding the robotic work tool to the charging station.