Lawn Care Robot

• US 20080109126A1
• Filed: 03/19/2007
• Published: 05/08/2008
• Est. Priority Date: 03/17/2006
• Status: Active Grant

• Current Assignee: iRobot Corporation
• Original Assignee: iRobot Corporation
• Inventors: Lewis, David, Bergman, John, Jones, Joseph, Cohen, David, Vu, Clara, Campbell, Tony, Dubrovsky, Zivthan, Gilbert, Duane, Sandin, Paul, Ozick, Daniel, Mammen, Jeffrey, Preneta, Joshua
• Granted Patent: US 8,634,960 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 2200/40 Working vehicles
• CPC Class Codes: B60L 2210/30 AC to DC converters
• CPC Class Codes: B60L 2210/40 DC to AC converters
• CPC Class Codes: B60L 2240/36 Temperature of vehicle components or parts
• CPC Class Codes: B60L 2240/425 Temperature
• CPC Class Codes: B60L 2240/662 Temperature
• CPC Class Codes: B60L 2250/16 by display
• CPC Class Codes: B60L 2260/32 Auto pilot mode
• CPC Class Codes: B60L 2270/145 Structure borne vibrations
• CPC Class Codes: B60L 3/0023 Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 50/52 characterised by DC-motors
• CPC Class Codes: B60L 50/62 charged by low-power generators primarily intended to support the batteries, e.g. range extenders
• CPC Class Codes: B60L 50/66 Arrangements of batteries
• CPC Class Codes: B60L 53/14 Conductive energy transfer
• 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 1/0255 using acoustic signals, e.g. ultra-sonic singals sonar systems designed for anti-collision purposes G01S15/93
• CPC Class Codes: G05D 1/0259 using magnetic or electromagnetic means
• CPC Class Codes: G05D 1/0261 using magnetic plots
• CPC Class Codes: G05D 1/0265 : using buried wires
• CPC Class Codes: G05D 1/028 : using a RF signal
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• 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: Y10S 901/01 : Mobile robot
• CPC Class Codes: Y10S 901/09 : Closed loop, sensor feedback controls arm movement

Abstract

A robot lawnmower includes a body and a drive system carried by the body and configured to maneuver the robot across a lawn. The robot also includes a grass cutter and a swath edge detector, both carried by the body. The swath edge detector is configured to detect a swath edge between cut and uncut grass while the drive system maneuvers the robot across the lawn while following a detected swath edge. The swath edge detector includes a calibrator that monitors uncut grass for calibration of the swath edge detector. In some examples, the calibrator comprises a second swath edge detector.

Claims

1. A robot lawnmower comprising:

a body;

a drive system carrier by the body and configured to maneuver the robot across a lawn;

a grass cutter carried by the body; and

a swath edge detector carried by the body and configured to detect a swath edge between cut and uncut grass while the drive system maneuvers the robot across the lawn while following a detected swath edge, the swath edge detector including a calibrator that monitors uncut grass adjacent the swath edge for calibration of the swath edge detector.

2. The robot lawnmower of claim 1 wherein the calibrator comprises a second swath edge detector.

3. The robot lawnmower of claim 1 wherein the swath edge detector comprises an array of grass length sensors spanning a distance comprising at least a steering error distance and a grass length sensor width, a first portion of the array arranged to detect the swath edge and a second portion of the array arranged to monitor uncut grass.

4. The robot lawnmower of claim 3 wherein the array of grass length sensors spans a distance of between about 4 and 10 inches.

5. The robot lawnmower of claim 1 wherein the swath edge detector comprises a plurality of sensor components, each sensor component comprising:

a sensor housing defining a cavity and a cavity opening configured to allow grass entry while inhibiting direct sunlight into the cavity;

an emitter carried by the housing in the cavity and configured to emit an emission across the cavity opening; and

a receiver carried by the housing and configured to receive a grass-reflected emission, the receiver positioned in the cavity to avoid exposure to direct sunlight.

6. The robot lawnmower of claim 1 wherein comprising a not-lawn detector carried by the body and responsive to non-grass surfaces, wherein the drive system is configured to redirect the robot in response to the detector detecting a non-grass surface.

7. The robot lawnmower of claim 1 wherein the not-lawn detector comprises:

a sensor housing defining emitter and receiver receptacles;

an audio transmitter carried in the emitter receptacle and transmitting an audio emission;

a receiver carried in the receiver receptacle an configured to receive an audio emission reflected off a ground surface;

wherein a controller of the robot compares a received reflected audio emission with a threshold energy to detect a non-grass surface.

8. The robot lawnmower of claim 7 wherein the audio transmitter transmits multiple audio emissions starting at a fundamental frequency and successively increasing the wavelength of each emission by half the fundamental frequency.

10. The robot lawnmower of claim 7 wherein the controller receives the reflected audio emission from the receiver through a narrow band-pass amplifier.

11. The robot lawnmower of claim 7 further comprising an anti-vibration mounting system securing the receiver in the receiver receptacle, the anti-vibration mounting system comprising a first elastic support holding the receiver in a tube below a sound absorber, the tube secured in the receiver receptacle with a second elastic support having a lower durometer than the first elastic support.

12. The robot lawnmower of claim 1 further comprising a side trimmer carried on a periphery of the body and configured to cut lawn adjacent the body.

13. The robot lawnmower of claim 1 further comprising at least one grass erector carried by the body and configured to erect grass.

14. The robot lawnmower of claim 13 wherein the grass erector comprises a driven wheel having an axis of rotation parallel to the lawn and a plurality of flexible grass agitators extending radially outward from the wheel.

9. (canceled)

15. (canceled)

16. A robot lawnmower swath edge detector system comprising:

a controller carried by a body of a robot; and

a plurality of grass length sensors carried by the body of the robot and in communication with the controller, each grass length sensors comprising;

a sensor housing defining a cavity and a cavity opening configured to allow grass entry while inhibiting direct sunlight into the cavity;

an emitter carried by the housing in the cavity and configured to emit an emission across the cavity; and

a receiver carried by the housing and configured to receive a grass-reflected emission, the receiver positioned in the cavity to avoid exposure to direct sunlight;

wherein the controller compares outputs from multiple ones of the grass length sensors to determine a swath edge location.

17. A robot lawnmower swath edge detector system of claim 16 wherein the plurality of grass length sensor spans a distance comprising at least a steering error distance and a grass length sensor width.

18. A robot lawnmower swath edge detector system of claim 16 wherein the plurality of grass length sensor spans a distance of between 4 and 10 inches.

20. A robot lawnmower of claim 16 wherein the driven wheel is supported by multiple rollers carried by the first body portion and driven by a pinion coupled to a motor carried by the first body portion.

19. A robot lawnmower comprising:

a first body portion defining a payload area and carrying a drive system having at least one driven wheel, the driven wheel having a diameter sized to circumscribe the payload area;

a controller configured to control the drive system to maneuver the lawnmower to traverse a lawn while cutting grass;

a second body portion joined to the first body portion by an articulated joint and carrying at least one free wheel;

an actuator actuable to rotate the first body portion relative to the second body portion at the articulated joint in response to a signal received from the controller; and

a grass cutter carried by at least one of the first and second body portions.

21. The robot lawnmower of claim 19 wherein the free wheel pivots along an axis perpendicular to an axis of rotation.

22. The robot lawnmower of claim 19 further comprising a swath edge detector carried by the first portion and configured to detect a swath edge between cut and uncut grass, wherein the drive system is configured to maneuver the robot across the lawn while following a detected swath edge.

23. The robot lawnmower of claim 22 wherein the swath edge detector includes a calibrator carried by the body and configured to monitor uncut grass, the controller in communication with the calibrator and configured to periodically compare the detected swath edge with monitored uncut grass.

24. A method of lawn cutting with a robot, the method comprising:

detecting a swath edge with a swath edge detector carried by the robot as the robot maneuvers itself across a lawn;

automatically comparing a detected swath edge with uncut grass monitored by a calibrator carried by the robot;

following the detected swath edge;

erecting blades of grass of the lawn with a grass erector of the robot; and

cutting the lawn with a cutter of the robot.

25. The method of claim 24 further comprising orienting blades of grass of the lawn with a grass orientor carried by the robot.

26. The method of claim 24 further comprising continuously scanning for an absence of lawn with a not-lawn detector carried by the robot, and automatically redirecting the robot in response to detecting an absence of lawn.

27. The method of claim 24 further comprising scanning for a boundary responder with a boundary detector system carried by the robot, and automatically redirecting the robot in response to detecting a boundary responder.