Selective plant discrimination

• US 20040149893A1
• Filed: 03/30/2004
• Published: 08/05/2004
• Est. Priority Date: 04/26/2001
• Status: Active Grant

• Current Assignee: WEED Control Australia Pty Limited
• Original Assignee: WEED Control Australia Pty Limited
• Inventors: Scott, Christopher C
• Granted Patent: US 7,081,611 B2
• Time in Patent Office: Days
• US Class Current: 250/221
• CPC Class Codes: A01B 79/005 Precision agriculture
• CPC Class Codes: A01M 21/043 by chemicals
• CPC Class Codes: A01M 7/0089 Regulating or controlling systems the delivery being related to the movement of a vehicle B05B9/06
• CPC Class Codes: G01N 2021/8466 Investigation of vegetal material, e.g. leaves, plants, fruits
• CPC Class Codes: G01N 21/3151 using two sources of radiation of different wavelengths G01N21/33 - G01N21/39 take precedence

Abstract

An apparatus (22) for selectively discriminating vegetation or plant matter (28) comprises a light emitting means (24), a light sensing means (30) and a distance sensing means (34). The light emitting means generates a beam of light (26) that can be directed onto plants or plant matter moving relative to the apparatus. The light sensing means senses light transmitted from said light emitting means and reflected from the plants or plant matter, and generates a reflection signal in response to the sensing of the reflected light. The distance sensing means senses the relative distance moved and generates a distance signal. A processing means (32) is operatively connected to the light sensing means and the distance sensing means to combine the reflection signal and distance signal to discriminate different types of plants or plant matter.

Claims

1. An apparatus for selectively discriminating vegetation or plant matter, the apparatus comprising:

light emitting means for generating a beam of light that can be directed onto plants or plant matter over which the light emitting means moves relative to the plants or plant matter;

light sensing means for sensing light transmitted from said light emitting means and reflected from said plants or plant matter, and generating a reflection signal in response to said sensing;

distance sensing means for sensing the relative distance moved in relation to said plants or plant matter by said light emitting means and generating a distance signal in response to said sensing; and

,

processing means operatively connected to said light sensing means and distance sensing means for combining said reflection signal and distance signal whereby, in use, different types of plants or plant matter can be discriminated.

2. An apparatus according to claim 1, wherein the processing means combines the reflection signal and distance signal to determine the size and/or shape of the plant or plant matter.

3. An apparatus according to either claim 1 or 2, wherein said distance sensing means includes a wheel encoder for sensing the speed at which a vehicle on which the apparatus is mounted is moving over the ground.

4. An apparatus according to claim 3, wherein said wheel encoder generates a signal in the form of a train of pulses or pulse count, wherein the frequency of the pulses is directly proportional to the speed at which the vehicle moves over the ground, as well as of the distance it has travelled.

5. An apparatus according to claim 3 or 4 wherein a separate wheel encoder is provided on each side of the vehicle, so that the processing means is able to identify when the vehicle is turning and adjust the response accordingly.

6. An apparatus according to any one of claims 1 to 5, wherein said light emitting means comprises a plurality of artificial light sources, each light source being adapted to transmit a beam of light at different wavelengths, whereby, in use, the reflection signal at each wavelength is used by the processing means in combination with the distance signal to discriminate plants or plant matter.

7. An apparatus according to any one of claims 1 to 6, wherein the processing means is programmed to combine the reflection signal and distance signal to discriminate one type of plant matter from another type of plant matter and/or one type of plant matter from non plant matter.

8. An apparatus according to any one of claims 1 to 7, said light sensing means comprises a plurality of sensor assemblies mounted in an array.

9. An apparatus according to claim 8, each sensor assembly comprises two or more sensors mounted in close proximity and each adapted to detect the reflected light at different wavelengths.

10. An apparatus according to claim 9, wherein the sensors employed are photodiodes.

11. An apparatus according to any one of claims 9 or 10, wherein a first sensor in each assembly is adapted to generate a sensing signal when it detects reflected light having a wavelength peaking between 550 nm and 650 nm.

12. An apparatus according to claim 11, wherein a second sensor in each assembly is adapted to generate a sensing signal when it detects reflected light having a wavelength peaking between 850 nm and 950 nm.

13. An apparatus according to any one of claims 9 to 12, wherein each sensor assembly includes one or more further sensors adapted to generate a sensing signal when each further sensor detects reflected light having a predetermined wavelength in the visible, near infra-red or infra red wave bands, wherein the processing means is operatively connected to the further sensors and the sensing signals from the further sensors are used to discriminate plants or plant matter.

14. An apparatus according to any one of claims 9 to 13, wherein two or more sensors are mounted concentrically in order to reduce the incidence of “

false positive”

spectral response.

15. An apparatus according to any one of the preceding claims, wherein the processing means is configured to produce an output signal when a target plant is identified or when an object that is not a target plant is identified.

16. An apparatus according to claim 15, wherein the apparatus includes a response means arranged to provide a response to the output signal.

17. An apparatus according to claim 16, wherein the response means is one or more of:

a solenoid valve arranged to operate a means for spraying;

or

a valve arranged to operate a means for distributing a powder or particulate material;

or

a recording means for recording the presence and location of the target plant and/or object;

a cutting means for cutting material in response to identification of the target plant or object;

or

a cultivating means.

18. A method for selectively discriminating vegetation, or plant matter, the method comprising the steps of:

generating a beam of light that can be directed onto plants or plant matter over which the light emitting means moves relative to the plant or plant matter;

sensing light transmitted from said light emitting means and reflected from said plants or plant matter, and generating a reflection signal in response to said sensing;

sensing the distance moved relative to said plants or plant matter by said light emitting means and generating a distance signal in response to said sensing; and

,

processing said reflection signal and distance signal to determine the spectral characteristics and size and/or shape of the plants or plant matter whereby, in use, different types of plants or plant matter, including weeds, can be discriminated.

19. A method according to claim 18, wherein the light is sensed by one or more sensor assemblies having one or more sensors.

20. A method according to claim 19, wherein the sensor assemblies travel over the ground and each of the sensors in the sensor assemblies continually senses light reflected upwards from the ground surface.

21. A method according to claim 19, wherein the plants or plant matter travel underneath the sensor assemblies and each of the sensors in the sensor assemblies continually sensed the light reflected upwards from the plants or plant matter travelling beneath.

22. A method according to either claim 20 or 21, wherein when a first affirmative spectral response signal occurs, the processing means begins to “

strobe”

the sensor assemblies so that they only operate to sense the presence or absence of plant matter at discretely spaced intervals.

23. A method according to claim 22, wherein readings from each of a plurality of sensor assemblies used for sensing the reflected light are taken at uniformly spaced intervals over the ground surface, and are typically triggered by pulses generated via a wheel encoder used for sensing the distance travelled over the plants.

24. A method according to claim 23, wherein the interval spacing is set at a fixed distance, typically between 0.2 mm and 2 mm when travelling in a straight line.