Robotic mower navigation system

• US 9,072,219 B2
• Filed: 06/20/2013
• Issued: 07/07/2015
• Est. Priority Date: 06/20/2013
• Status: Active Grant

• Current Assignee: Deere & Company
• Original Assignee: Deere & Company
• Inventors: Hahnenkamp, Sven, Foley, Mark, Da Rocha, Francisco O
• Primary Examiner(s): To, Tuan C.
• Assistant Examiner(s): PATEL, SHARDUL D
• Application Number:
  US13/857,434
• Publication Number:
  US 20140379196A1
• Time in Patent Office: 747 Days
• Field of Search: 701/2, 701/23, 701/26, 701/400, 700/258, 324/654, 901/1
• US Class Current: 1/1
• CPC Class Codes: A01D 34/008 for automated or remotely controlled operation
• CPC Class Codes: B60L 15/2036 Electric differentials, e.g. for supporting steering vehicles
• CPC Class Codes: B60L 2200/40 Working vehicles
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/461 Speed
• CPC Class Codes: B60L 2250/16 by display
• CPC Class Codes: B60L 2260/32 Auto pilot mode
• CPC Class Codes: B60L 2260/46 by self learning
• CPC Class Codes: B60L 3/12 Recording operating variables ; Monitoring of operating variables
• CPC Class Codes: B60L 50/52 characterised by DC-motors
• CPC Class Codes: B60L 53/18 Cables specially adapted for charging electric vehicles
• CPC Class Codes: B60L 58/21 having the same nominal voltage
• 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: 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
• CPC Class Codes: Y02T 90/167 : Systems integrating technologies related to power network operation and communication or information technologies for supporting the interoperability of electric or hybrid vehicles, i.e. smartgrids as interface for battery charging of electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: Y04S 30/12 : Remote or cooperative charging
• CPC Class Codes: Y10S 901/01 : Mobile robot

Abstract

A robotic mower navigation system includes a plurality of sensors on a robotic mower that detect strength and polarity of a magnetic field from an electric current through a boundary wire. An electronic control unit receives data concerning the magnetic field from the plurality of sensors as the robotic mower follows the boundary wire, tracks the data provided by the sensors, compares the data with a reference pattern that defines at least one specified feature of the boundary wire, and provides commands to the robotic mower based on the comparison. The electronic control unit may command the robotic mower to follow a second boundary wire to a remotely located charging station instead of the first boundary wire based on detected features of the boundary wire such as sharp corners or crossings.

Claims

1. A robotic mower navigation system, comprising:

a robotic mower having a plurality of sensors that detect strength and polarity of a magnetic field from an electric current through a boundary wire; and

an electronic control unit receiving data concerning the magnetic field from the plurality of sensors as the robotic mower follows the boundary wire, determining if the data shows an abrupt change in polarity and signal strength along the boundary wire indicating a specified geometric feature of the boundary wire, tracking the data for a sequence of the specified geometric features, comparing the data with a plurality of reference patterns that define location along the boundary wire, and providing a command to the robotic mower based on the comparison.

2. The robotic mower navigation system of claim 1 wherein at least one specified feature of the boundary wire is a sharp corner.

3. The robotic mower navigation system of claim 1 wherein at least one specified feature of the boundary wire is a sharp crossing with a second boundary wire.

4. The robotic mower navigation system of claim 1 wherein the electronic control unit provides a command to move away from the boundary wire.

5. The robotic mower navigation system of claim 1 wherein the electronic control unit provides a command to follow a second boundary wire.

6. The robotic mower navigation system of claim 1 wherein the plurality of sensors includes a left sensor, a center sensor and a right sensor;

the center sensor being closest to the boundary wire that is followed.

7. A robotic mower navigation system comprising:

a first boundary wire around a perimeter of an area;

a second boundary wire crossing the first boundary wire at least once;

a charging station connected to the first and the second boundary wires and providing current through the first and second boundary wires; and

a vehicle control unit commanding a robotic mower to follow the second boundary wire to the charging station instead of the first boundary wire by detecting and tracking abrupt changes in polarity and signal strength at each of a plurality of sharp crossings of the first and the second boundary wires, determining if the data shows an abrupt change in polarity and signal strength along the boundary wire indicating a specified geometric feature of the boundary wire.

8. The robotic mower navigation system of claim 7 wherein the vehicle control unit tracks the number of sharp crossings of the first and the second boundary wires.

9. The robotic mower navigation system of claim 7 wherein the vehicle control unit detects sharp crossings of the first and second boundary wires by comparing polarity and signal strength data from a plurality of sensors on the robotic mower with a known change pattern.

10. The robotic mower navigation system of claim 7 wherein the charging station is at a remote location from the area.

11. The robotic mower navigation system of claim 7 wherein the vehicle control unit commands the robotic mower to stop mowing when following the second boundary wire to the charging station.

12. The robotic mower navigation system of claim 7 wherein the vehicle control unit also detects sharp corners of the first and second boundary wires by comparing polarity and signal strength data from a plurality of sensors on the robotic mower with a known change pattern.

13. A robotic mower navigation system comprising:

a plurality of boundary wires, each boundary wire forming a loop having ends connected to a charging station which provides current pulses that create an electromagnetic field along each boundary wire;

each boundary wire driven with current pulses having different characteristics such that those pulses can be identified by a vehicle control unit on a robotic mower;

a plurality of boundary wire features based on how the boundary wires are placed on or below a yard surface and including geometries for how each of the boundary wires changes direction or crosses another boundary wire;

a plurality of sensors on the robotic mower that sense the electromagnetic field along each boundary wire and provide data to the vehicle control unit;

the vehicle control unit tracking each abrupt change in polarity and signal strength resulting from each of the boundary wire features and commanding a traction drive motor and a mowing motor to operate in a specified area based on the boundary wire tracking.

14. The robotic mower navigation system of claim 13 wherein the boundary wires define a plurality of sub-areas;

the vehicle control unit commanding the traction drive motor and the mowing motor to operate the robotic mower in specified sub-areas based on the boundary wire feature tracking.

15. The robotic mower navigation system of claim 13 wherein the boundary wire features include sharp angle corners and sharp angle crossings.

16. The robotic mower navigation system of claim 13 wherein one of the plurality of boundary wires provides a path to a location that is remotely located from an area enclosed by another boundary wire.

17. The robotic mower navigation system of claim 13 wherein the vehicle control unit identifies features of the boundary wire by comparing a change history of data received from the plurality of sensors with known change patterns.