Robotic mower boundary sensing system

• US 8,392,044 B2
• Filed: 07/28/2010
• Issued: 03/05/2013
• 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:
  US12/845,326
• Publication Number:
  US 20120029754A1
• Time in Patent Office: 951 Days
• Field of Search: 701/23, 701/25, 701/26, 701/50, 701/532, 318/568.12, 318/587, 318/581, 318/580, 318/250, 180167-169
• 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 boundary sensor on the 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 determining the distance of the boundary sensor to the boundary wire using a cross correlation function to provide a time lag difference between a known waveform at a known distance to the boundary wire and a sampled waveform from the encoded signal, the time lag having an amplitude proportional to the difference between a maximum amplitude of the known waveform and a maximum amplitude of the sampled waveform.

2. The robotic mower boundary sensing system of claim 1 wherein the encoded signal includes a Barker code.

3. The robotic mower boundary sensing system of claim 1 further comprising a plurality of boundary sensors on the front of the robotic mower.

4. The robotic mower boundary sensing system of claim 3 wherein the vehicle control unit uses information from a plurality of sensors to determine the angular orientation of the robotic mower relative to the boundary wire.

5. 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 boundary sensor on the robotic mower; and

a boundary sensor on the robotic mower; and

a vehicle control unit connected to the boundary sensor and cross correlating the signal received from the boundary sensor to a known signal at a known distance to the boundary wire to determine the distance of the boundary sensor to the boundary wire;

the cross correlation providing a time lag with an amplitude proportional to the difference between a maximum amplitude of the known signal and a maximum amplitude of the sampled signal.

6. The robotic mower boundary sensing system of claim 5 wherein the vehicle control unit converts the boundary wire signal from an analog signal to digital values that are buffered.

7. The robotic mower boundary sensing system of claim 5 wherein the vehicle control unit uses the peak to peak amplitude of the known signal as the maximum signal.

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 a sampled waveform at an unknown distance to the boundary wire;

determines the time lag difference between the known waveform and sampled waveform; and

calculates the distance to the boundary wire based on the amplitude of the lag.

9. The robotic mower boundary sensing system of claim 8 further comprising a boundary sensor with a sense coil connected to the vehicle control unit.

10. The robotic mower boundary sensing system of claim 8 wherein the vehicle control unit converts the known waveform and the sampled waveform from the time domain to the frequency domain.