SYSTEM AND METHOD FOR NAVIGATING A ROBOTIC WORKING TOOL

• US 20160334795A1
• Filed: 12/19/2013
• Published: 11/17/2016
• Est. Priority Date: 12/19/2013
• Status: Active Grant

• Current Assignee: Husqvarna AB (HUSQVARNA)
• Original Assignee: Husqvarna AB (HUSQVARNA)
• Inventors: Reigo, Peter, Grufman, Stefan
• Granted Patent: US 10,078,336 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A01D 34/008 for automated or remotely controlled operation
• CPC Class Codes: B60L 1/003 to auxiliary motors, e.g. for pumps, compressors
• CPC Class Codes: B60L 2200/40 Working vehicles
• CPC Class Codes: B60L 2220/46 Wheel motors, i.e. motor connected to only one wheel
• CPC Class Codes: B60L 2240/62 Vehicle position
• CPC Class Codes: B60L 2260/32 Auto pilot mode
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/52 characterised by DC-motors
• CPC Class Codes: B60L 53/30 Constructional details of charging stations
• CPC Class Codes: G05D 1/027 comprising intertial navigation means, e.g. azimuth detector inertial navigation G01C21/16; inertial navigation combined with non-inertial navigation instruments G01C21/165
• CPC Class Codes: G05D 1/0278 using satellite positioning signals, e.g. GPS
• 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 90/12 Electric charging stations
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles
• CPC Class Codes: Y02T 90/16 Information or communication technologies improving the operation of electric vehicles

Abstract

A robotic work tool system (200) comprising a robotic work tool (100), said robotic work tool (100) comprising a position determining device (190) for determining a current position, such as through receiving satellite signals, and a navigation device (195) arranged to at least provide a compass heading, the robotic work tool (100) being configured to: determine a compass heading (CH) obtained through the navigation device (195); compare the compass heading to a true heading (TH) obtained through the position determining device (190); determine an error (e) between the true heading (TH) and the compass heading (CH); determine a robot position (XR;YR); and store the error (e) for said robot position (XR;YR) thereby generating a magnetic correction matrix.

Claims

1. A robotic work tool system comprising a robotic work tool, said robotic work tool comprising a position determining device for determining a current position, via receiving satellite signals, and a navigation device arranged to at least provide a compass heading, the robotic work tool being configured to:

determine a compass heading obtained through the navigation device;

compare the compass heading to a true heading obtained through the position determining device;

determine an error (e) between the true heading and the compass heading;

determine a robot position; and

store the error for said robot position thereby generating a magnetic correction matrix.

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

determine that reception of a satellite signal is no longer reliably received;

determine a current robot position;

start navigating via the navigation device;

retrieve a correction value from the magnetic correction matrix for said current position and to adapt the compass heading accordingly.

3. The robotic work tool system according to claim 2, wherein the robotic work tool is configured to retrieve the correction value from the magnetic correction matrix continuously.

4. The robotic work tool system according to claim 2, wherein the robotic work tool is configured to retrieve the correction value from the magnetic correction matrix at intervals.

5. The robotic work tool system according to claim 2, wherein the robotic work tool is further configured to determine that a correction value is not available for the current robot position and in response thereto use the latest retrieved correction value as the correction value with which to adapt the compass heading.

6. The robotic work tool system according to claim 2, wherein the robotic work tool is further configured to determine that a correction value is not available for the current robot position and in response thereto:

estimate a next available correction value, by searching the magnetic correction matrix for a correction value that corresponds to a position that is on a current path of the robotic work tool and

use such a predicted correction value as the correction value with which to adapt the compass heading.

7. The robotic work tool system according to claim 2, wherein the robotic work tool is further configured to determine that a correction value is not available for the current robot position and in response thereto:

estimate a next available correction value, by searching the magnetic correction matrix for a correction value that corresponds to a position that is on a current path of the robotic work tool;

determine an average of the last used correction value and a predicted correction value; and

use the average correction value as the correction value to be added with which to adapt the compass heading.

8. The robotic work tool system according to claim 2, wherein the robotic work tool is further configured to determine that a correction value is not available for the current robot position and in response thereto

determine an average correction value for the magnetic correction matrix, and use the average correction value as the correction value with which to adapt the compass heading.

9. The robotic work tool system according to claim 2, wherein the robotic work tool is further configured to determine that a correction value is not available for the current robot position and in response thereto

determine an area currently being worked in;

determine an average correction value for the currently worked in area from the magnetic correction matrix; and

use the average correction value as the correction value with which to adapt the compass heading.

10. The robotic work tool system according to claim 1, wherein the robotic work tool is configured to continuously or at intervals update the magnetic correction matrix to accommodate for changes in the environment.

11. The robotic work tool system according to claim 1, wherein the robotic work tool is configured to store a time point for each robot position in the magnetic correction matrix and compare a current time with the time point for a position in the magnetic correction matrix and to select a correction value corresponding to the position and the time point, said selected correction value with which to adapt the compass heading.

12. The robotic work tool system according to claim 1, wherein the position determining device is a Global Navigation Satellite System device.

13. The robotic work tool system according to claim 1, wherein the robotic work tool is a robotic lawnmower.

14. The robotic work tool system according to claim 1, wherein the robotic work tool is a farming equipment, a vacuum cleaner, a floor cleaner, a street sweeper, a snow removal tool, a golf ball retriever robot, a cleaner robot, a leaves blower robot, a leaves collector robot, snow thrower robot or a mine clearance robot.

16. The method according to claim 14, wherein the method further comprises:

determining that reception of a satellite signal is no longer reliably received;

determining a current robot position;

starting to navigate via the navigation device;

retrieving a correction value from the magnetic correction matrix for said current position and adapting the compass heading accordingly.

15. A method for use in a robotic work tool system, comprising a robotic work tool, said robotic work tool comprising a position determining device for determining a current position, such as through receiving satellite signals, and a navigation device arranged to at least provide a compass heading, the method comprising:

determining a compass heading obtained through the navigation device;

comparing the compass heading to a true heading obtained through the position determining device;

determining an error between the true heading and the compass heading;

determining a robot position; and

storing the error for said robot position thereby generating a magnetic correction matrix.