METHOD AND SYSTEM FOR GUIDING A ROBOTIC GARDEN TOOL

• US 20130184924A1
• Filed: 10/01/2010
• Published: 07/18/2013
• Est. Priority Date: 10/01/2010
• Status: Active Grant

• Current Assignee: Husqvarna AB (HUSQVARNA)
• Original Assignee: Husqvarna AB (HUSQVARNA)
• Inventors: Jgenstedt, Patrik, Bergvall, Bengt-Allan
• Granted Patent: US 9,405,294 B2
• Time in Patent Office: Days
• US Class Current: 701/23
• CPC Class Codes: A01D 34/008 for automated or remotely controlled operation
• 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: G05D 1/0219 ensuring the processing of the whole working surface
• 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 1/0259 using magnetic or electromagnetic means
• CPC Class Codes: G05D 1/0265 using buried wires
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility
• CPC Class Codes: Y10S 901/01 Mobile robot

Abstract

Method and system for guiding a robotic garden tool (100) is disclosed. The robotic garden tool (100) may include at least two sensing means (108, 110, and 202). The robotic garden tool (100) is equipped to follow along a guiding wire (402) on a lawn (400). While the robotic garden tool (100) moves along the guiding wire (402), the sensing means (108, 110, and 202) may detect a magnetic field strength generated from current carrying guiding wire (402). The method (500) and the system (300) is equipped to provide instructions to the robotic garden tool (100) to follow the guiding wire (402) based on the difference of magnetic field strength sensed by at least two sensing means (108, 110, and 202).

Claims

1. A guiding system for a robotic garden tool, the guiding system comprising:

at least one guiding wire adapted to conduct electric current such that a magnetic field is generated adjacent to the guiding wire, and

a robotic garden tool adapted to follow the guiding wire at a distance from the guiding wire,

wherein the robotic garden tool further comprises a first sensing means and a second sensing means placed on the robotic garden tool such that they will have different distance to the guiding wire when the robotic garden tool moves along the guiding wire, wherein each of the first sensing means and second sensing means are adapted to detect a strength of the magnetic field, and wherein the robotic garden tool is adapted to use the difference between the detected magnetic field strength in the first sensing means and the detected magnetic field strength in the second sensing means for steering along the guiding wire.

2. A guiding system according to claim 1, wherein at least one of the first sensing means and second sensing means are adapted to detect the strength of a vertical component in the magnetic field.

3. A guiding system according to claim 1, wherein the first sensing means and the second sensing means are placed on the robotic garden tool with a distance between each other along the longitudinal axis of the robotic garden tool.

4. A guiding system according to claim 3, wherein the distance between the first sensing means and the second sensing means along the longitudinal axis of the robotic garden tool is between 4-30 cm.

5. A guiding system according to claim 1, wherein the distance between the first sensing means and the second sensing means in a direction perpendicular to a longitudinal axis of the robotic garden tool is between 5-35 cm.

6. A guiding system according to claim 1, wherein the robotic garden tool further comprises a third sensing means, wherein the sensing means are placed on the robotic garden tool in a triangle shape, such that the second sensing means and the third sensing means are placed along a line substantially perpendicular to the longitudinal axis of the robotic garden tool, and the first sensing means is placed in front of the line along the longitudinal axis of the robotic garden tool.

7. A guiding system according to claim 6, wherein the distance between the first sensing means and the line along which the second sensing means and the third sensing means are placed, is between 4-30 cm.

8. A guiding system according to claim 6, wherein the angle between the longitudinal axis of the robotic garden tool and a line joining the first sensing means to any one of the second sensing means and the third sensing means is between 40-80°

.

9. A guiding system according to claim 1, wherein the guiding wire is a perimeter limiting wire.

10. A guiding system according to claim 1, wherein the guiding wire is adapted to conduct a non-constant current.

11. A method for guiding a robotic garden tool, the robotic garden tool is provided with a first sensing means and a second sensing means,

the method comprising the steps wherein the robotic garden tool;

follows a guiding wire at a distance from the guiding wire, the guiding wire conducts electric current such that a magnetic field is generated adjacent to the guiding wire,

detects the strength of the magnetic field from the guiding wire in the first and second sensing means, wherein the first and second sensing means are placed on the robotic garden tool such that they will have different distance from the guiding wire when the robotic garden tool moves along the guiding wire,

steers along the guiding wire based on the difference between the detected magnetic field strength in the first sensing means and the detected magnetic field strength in the second sensing means.

12. A method according to claim 11, wherein the robotic garden tool follows a path along the guiding wire such that the difference of magnetic field strength detected by the first sensing means and the second sensing means is a constant value throughout an operating cycle of the robotic garden tool.

13. A method according to claim 11 further comprises the step wherein the robotic garden tool detects the strength of the magnetic field from the guiding wire in a third sensing means, wherein the second sensing means and the third sensing means are placed along a line substantially perpendicular to the longitudinal axis of the robotic garden tool, and the first sensing means is placed in front of the line on the longitudinal axis of the robotic garden tool.

14. A method according to claim 13, wherein the robotic garden tool is steered along the guiding wire based on the difference between the detected magnetic field strength in the first sensing means and detected magnetic field strength in one of the second sensing means and the third sensing means, whichever is closer to the guiding wire.

15. A method according to claim 13, wherein the robotic garden tool is steered along the guiding wire based on the difference between the detected magnetic field strength in the first sensing means and detected magnetic field strength in one of the second sensing means and the third sensing means, whichever is farther from the guiding wire.