Robotic mower boundary sensing system

• US 8,706,339 B2
• Filed: 12/21/2012
• Issued: 04/22/2014
• Est. Priority Date: 07/28/2010
• Status: Active Grant

• Current Assignee: Deere & Company
• Original Assignee: Deere & Company
• Inventors: Thompson, Jeffrey S., Rupp, Craig E
• Primary Examiner(s): Black, Thomas
• Assistant Examiner(s): HUYNH, LUAT T
• Application Number:
  US13/724,159
• Publication Number:
  US 20130211704A1
• Time in Patent Office: 487 Days
• Field of Search: 701/300, 701 23- 26, 701/2, 701/50, 700/245, 700/253, 700/258, 901/1, 901/21
• US Class Current: 701/23
• CPC Class Codes: A01D 34/006 Control or measuring arrangements
• 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 15/2036 Electric differentials, e.g. for supporting steering vehicles
• CPC Class Codes: B60L 2200/40 Working vehicles
• CPC Class Codes: B60L 2220/20 DC electrical machines
• CPC Class Codes: B60L 2220/46 Wheel motors, i.e. motor connected to only one wheel
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/22 Yaw angle
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2250/16 by display
• CPC Class Codes: B60L 2260/32 Auto pilot mode
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 53/14 Conductive energy transfer
• CPC Class Codes: B60L 53/65 involving identification of vehicles or their battery types
• CPC Class Codes: B60L 58/21 having the same nominal voltage
• CPC Class Codes: G01S 5/0205 Details
• 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 90/12 : 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
• 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 30/14 : Details associated with the interoperability, e.g. vehicle recognition, authentication, identification or billing
• CPC Class Codes: Y10S 901/01 : Mobile robot

Abstract

A robotic mower boundary sensing system includes a boundary driving circuit on a charging station transmitting an encoded signal on a boundary wire, a boundary sensor on a robotic mower and including an inductor receiving the encoded signal, and a vehicle control unit on the robotic mower receiving the encoded signal from the boundary sensor and decoding the signal and cross correlating the received signal to determine the distance of the boundary sensor from the boundary wire.

Claims

1. A robotic mower boundary sensing system, comprising:

a boundary driving circuit on a charging station transmitting an encoded signal on a boundary wire;

a plurality of boundary sensors on the robotic mower, each sensor including an inductor receiving the encoded signal; and

a vehicle control unit on the robotic mower receiving the encoded signal from each of the plurality of sensors and decoding the signal and determining the distance of each of the plurality of sensors to the boundary wire using a cross correlation function to provide a difference in signal strength between a known waveform at a known distance to the boundary wire and a sampled waveform from each encoded signal.

2. The robotic mower boundary sensing system of claim 1 wherein the vehicle control unit converts the encoded signal from a time domain to a frequency domain.

3. The robotic mower boundary sensing system of claim 2 wherein the vehicle control unit converts the known waveform and the sampled waveforms from the time domain to the frequency domain.

4. The robotic mower boundary sensing system of claim 1 further comprising at least one sensor at a front of the robotic mower and at least one sensor at a back of the robotic mower.

5. The robotic mower boundary sensing system of claim 1 wherein the vehicle control unit uses information from the plurality of boundary sensors to determine the angular orientation of the robotic mower relative to the boundary wire.

6. A robotic mower boundary sensing system, comprising:

an outer boundary wire connected to a charging station;

the outer boundary wire providing a signal that is detected by a plurality of boundary sensors on the robotic mower; and

a vehicle control unit connected to the boundary sensors and cross correlating the signal received from each boundary sensor to a known signal at a known distance to the boundary wire to determine the distance of each boundary sensor to the boundary wire based on the strength of the signal from the main boundary wire to indicate proximity of each sensor to the wire.

7. The robotic mower boundary sensing system of claim 6 wherein the vehicle control unit performs the cross correlation by converting the signals from each boundary sensor from a time domain to a frequency domain.

8. A robotic mower boundary sensing system, comprising:

a vehicle control unit that cross correlates a known waveform at a known distance to a boundary wire with sampled waveforms from a first boundary sensor and a second boundary sensor at unknown distances to the boundary wire;

determines the proximity of the first sensor and the second sensor to the boundary wire; and

calculates the difference between the proximity of the first sensor to the boundary wire, and the proximity of the second sensor to the boundary wire.