JP7736652B2 - mobile weeding device - Google Patents

Description

This disclosure relates to a mobile weeding device.

Weeding devices that use laser irradiation to remove unwanted plants (i.e., weeds) from agricultural land are known (see Patent Documents 1-3). These weeding devices irradiate unwanted plants with laser light from above, damaging and killing the plants.

JP 2015-53941 A JP 2015-53942 A JP 2015-62412 A

Weeding devices that use laser light recognize unwanted plants to be removed, for example, through image processing. However, if water or other liquids adhere to the unwanted plants, the accuracy of recognizing the unwanted plants decreases due to the reflection of light.

One aspect of the present disclosure aims to provide a mobile weeding device that can efficiently remove unwanted plants in an environment where liquid adheres to the unwanted plants.

One aspect of the present disclosure is a mobile weeding device that includes a laser irradiator configured to irradiate a plant with laser light from above the plant, a camera configured to capture an image of the plant from above, a control device configured to identify the plant based on the image, a shielding wall arranged to surround the laser light irradiation space, and a device main body that holds the laser irradiator and the shielding wall and has a movement mechanism. The inner surface of the shielding wall is made of a low-reflectivity material.

With this configuration, the laser light irradiation space (i.e., the unwanted plant identification space) is surrounded by a shielding wall with an inner surface made of a low-reflectivity material, which reduces the reflection of light by liquid within the irradiation space. The shielding wall also reduces the impact of external light, such as natural light, on the image. As a result, the accuracy of unwanted plant recognition is improved, allowing unwanted plants to be removed efficiently.

In one aspect of the present disclosure, the shielding wall may have a light-blocking base material and an inner layer made of a low-reflectivity material disposed on the inner surface of the base material. This configuration prevents light from entering the shielding wall from outside, thereby stabilizing the brightness in the space irradiated with laser light. As a result, the accuracy of recognizing unwanted plants is improved.

In one aspect of the present disclosure, the low-reflectivity material may be an anti-reflection film or an anti-reflection coating. With this configuration, a relatively simple shielding wall configuration can suppress light reflection in the laser light irradiation space.

In one aspect of the present disclosure, the inner surface of the shielding wall may be dark in color. This configuration can enhance the effect of suppressing light reflection in the space irradiated with laser light.

In one aspect of the present disclosure, the arithmetic mean roughness Ra of the inner surface of the shielding wall may be 50 μm or more. This configuration can enhance the effect of suppressing light reflection in the space irradiated with laser light.

In one aspect of the present disclosure, the wavelength of the laser light may be 400 nm or more and 550 nm or less. With this configuration, the laser light is less likely to be absorbed by the liquid, thereby increasing the efficiency of removing unwanted plants.

One aspect of the present disclosure may further include a water injector configured to inject water into the area irradiated with the laser light. This configuration can suppress the generation of smoke due to laser light irradiation. Furthermore, even if the injected water adheres to unwanted plants before removal, the shielding wall can suppress light reflection.

FIG. 1 is a schematic side view of a mobile weeding device according to an embodiment. FIG. 2 is a schematic diagram showing an example of a movement path of the mobile weeding device of FIG. FIG. 3 is a schematic diagram showing an example of liquid adhesion on unwanted plants. FIG. 4 is a block diagram showing the configuration of the control device in the mobile weeding device of FIG. FIG. 5 is a schematic front view of the mobile weeding device of FIG. 1. FIG. 6 is a schematic cross-sectional view of a shielding wall in the mobile weeding device of FIG. 1.

Hereinafter, embodiments to which the present disclosure is applied will be described with reference to the drawings.
1. First embodiment
[1-1. Configuration]
The mobile weeding device 1 shown in Figure 1 is a device for removing unwanted plants P2 (i.e., weeds) that have grown around crops P1 in farmland. The mobile weeding device 1 includes a device main body 2, a laser irradiator 3, a camera 4, lighting 5, a water sprayer 6, a monitoring sensor 7, a control device 9, and a shielding wall 10.

<Device body>
The device main body 2 is a housing that holds the laser irradiator 3, the camera 4, the lighting 5, the water sprayer 6, the monitoring sensor 7, the control device 9, and the shielding wall 10. The device main body 2 also has a movement mechanism.

The movement mechanism in this embodiment is composed of multiple wheels 21. The device main body 2 is configured to travel on farmland using the multiple wheels 21. The movement mechanism may be an electric type that uses a motor to rotate the wheels 21, or a manual type that moves the device main body 2 by pushing or pulling it. The device main body 2 may also be equipped with one or more electric crawlers instead of wheels 21 as its movement mechanism.

As shown in Figure 2, the mobile weeding device 1 travels along the longitudinal direction of multiple ridges F. The mobile weeding device 1 irradiates laser light and sprays water onto unwanted plants P2 for each of the multiple ridges F.

As shown in Figure 3, liquids such as water, pesticides, and liquid fertilizer may adhere to unwanted plants P2 as droplets W1. Liquid also exists as puddles W2 in the furrows F (i.e., the ground) where unwanted plants P2 are located. Droplets W1 and puddles W2 reflect natural light or light from lighting 5, forming white areas in the image captured by camera 4.

<Laser irradiator>
1 is configured to irradiate the unwanted plant P2 with laser light L from above the unwanted plant P2 identified by the control device 9. The laser irradiator 3 may be configured to irradiate the unwanted plant P2 with laser light L from above by changing the direction of the laser light L using an optical element such as a mirror.

The laser irradiator 3 uses laser light L to damage (specifically burn) the unwanted plants P2, causing them to wither and die. The laser light L is irradiated onto the growth point or base of the unwanted plants P2. The growth point and base of the unwanted plants P2 are determined by the control device 9 based on images captured by the camera 4.

The laser irradiator 3 can be a known laser irradiation device that has a battery, an oscillator, and a reflection control unit (e.g., a galvanometer scanner, MEMS, etc.). The wavelength of the laser light from the laser irradiator 3 is 400 nm or more and 550 nm or less.

The laser irradiator 3 is configured to be able to change the irradiation direction, irradiation output, and irradiation time of the laser light L. The irradiation output is changed by a signal (e.g., an analog input voltage) output from the control device 9 to the oscillator.

The laser irradiator 3 may irradiate the laser while the device main body 2 is moving, or while the device main body 2 is stationary. The laser irradiator 3 sequentially irradiates the laser on multiple unwanted plants P2 identified by the control device 9.

<Camera>
The camera 4 is configured to acquire an image taken from above of farmland containing at least one crop P1 and at least one unwanted plant P2.

The images captured by camera 4 include at least one crop P1, at least one unwanted plant P2, and other objects (e.g., structures such as fences, obstacles such as stones, etc.). The imaging range of camera 4 changes as device main body 2 moves.

<Lighting>
The lighting 5 is configured to illuminate the photographing area of the camera 4. That is, the lighting 5 irradiates light onto at least one unwanted plant P2.

<Water injector>
The water injector 6 is configured to inject water for fire extinguishing onto the area irradiated with the laser light L from above.

Specifically, the water injector 6 injects water toward the unwanted plants P2 after they have been irradiated with the laser light L. The coordinates and range over which the water injector 6 injects water are set by the control device 9. Water is supplied to the water injector 6 from, for example, a water tank (not shown) installed in the device main body 2.

<Monitoring sensor>
The monitoring sensor 7 is a known device that detects the temperature and the presence or absence of smoke in the area irradiated with the laser light.

<Control device>
The control device 9 mainly controls the laser irradiator 3 and the water injector 6. The control device 9 is configured by a computer including, for example, a processor, a storage medium such as a RAM or a ROM, a communication unit, and an input/output unit. As shown in FIG. 4 , the control device 9 has an image processing unit 91, a laser control unit 92, an injection control unit 93, and a database 94.

The image processing unit 91 is configured to identify unwanted plants P2 from images captured by the camera 4. The image processing unit 91 identifies unwanted plants P2 using AI (artificial intelligence) developed using known statistical methods.

Statistical methods include, for example, supervised machine learning and multivariate analysis. In supervised machine learning, a decision formula (i.e., a classifier) is constructed by analyzing a large number of labeled plant images (i.e., training data) using a machine learning circuit.

The image processing unit 91 sets a target area for the unwanted plant P2 that includes the growing point or base of the unwanted plant P2 identified by AI. The growing point is a part that contains tissue with active cell division, mainly at the tip of the plant stem, and can be identified depending on the type of plant.

The laser control unit 92 instructs the laser irradiator 3 to irradiate laser light onto the coordinates of the unwanted plant P2 identified by the image processing unit 91. Specifically, the laser control unit 92 instructs the laser irradiator 3 to irradiate laser light onto the target area set by the image processing unit 91.

The spray control unit 93 instructs the water injector 6 to spray water onto areas where the monitoring sensor 7 detects high temperatures or areas where smoke is detected. Furthermore, regardless of the detection results of the monitoring sensor 7, the spray control unit 93 may instruct the water injector 6 to spray water onto the unwanted plants P2 that have been irradiated with laser light after the laser irradiator 3 has completed irradiating the unwanted plants P2 with laser light.

The control device 9 may be configured to output the results of identification of unwanted plants P2 by the image processing unit 91, the temperature and smoke detection results by the monitoring sensor 7, etc., to a monitor installed in the device main body 2.

<Shielding wall>
As shown in FIG. 5, the shielding wall 10 is a cylindrical member arranged to surround the space irradiated with the laser light L from the laser irradiator 3 .

In this embodiment, the shielding wall 10 has a rectangular cylindrical shape that surrounds the irradiation space of the laser light L on all sides. However, the shielding wall 10 may have a polygonal cylindrical shape other than a rectangular cylindrical shape, or may be cylindrical. Also, in this embodiment, the shielding wall 10 does not have any openings or holes. Furthermore, the upper end of the shielding wall 10 is closed by the device main body 2.

As shown in Figure 6, the shielding wall 10 has a base material 11 and an inner layer 12. The base material 11 is made of a light-blocking material such as a steel plate, resin plate, or cloth. From the standpoint of weather resistance and durability, stainless steel plate or plated steel plate, for example, is suitable as the material for the base material 11.

The inner layer 12 is disposed by being superimposed on the inner surface of the substrate 11 (i.e., the surface facing the irradiation space of the laser light L). The inner layer 12 forms the inner surface of the shielding wall 10 (i.e., the surface facing the irradiation space of the laser light L). The inner layer 12 is made of a low-reflectivity material. Therefore, the inner surface of the shielding wall 10 is made of a low-reflectivity material.

A low-reflectivity material is a material with a surface reflectivity of less than 10%. In other words, the reflectivity of the inner surface of the shielding wall 10 is less than 10%. An anti-reflection film or anti-reflection coating is suitable as the low-reflectivity material that makes up the inner layer 12.

The anti-reflection film is attached to the inner surface of the substrate 11, for example, with an adhesive. The anti-reflection coating is formed by applying, for example, an anti-reflection agent to the inner surface of the substrate 11. The anti-reflection film or anti-reflection coating can suppress light reflection in the laser light irradiation space with a relatively simple shielding wall 10 configuration.

The inner surface of the shielding wall 10 (i.e., the inner surface of the inner layer 12) is preferably a dark color. In other words, the inner layer 12 preferably contains a dark-colored paint. A dark-colored inner surface of the shielding wall 10 can enhance the effect of suppressing light reflection in the space irradiated with the laser light L. Note that a "dark color" is a color with a brightness of 1 or less in the Munsell color system.

The arithmetic mean roughness Ra of the inner surface of the shielding wall 10 is preferably 50 μm or greater. Having such a rough surface on the inner surface of the shielding wall 10 can enhance the effect of suppressing light reflection in the space irradiated with the laser light L.

The shielding wall 10 also functions to prevent the laser light L from scattering outside the irradiation space. This protects the worker from the laser light L, thereby increasing safety during weeding work.

As shown in Figure 5, the shielding wall 10 has an upper portion 10A and a lower portion 10B. The lower portion 10B is a portion that may interfere with crops P1 or unwanted plants P2 that have grown to a certain extent when the device main body 2 is moved. In other words, the lower portion 10B is a portion that is within a certain range of distance (i.e., height) from the surface of the farmland. The upper portion 10A is a portion higher than the lower portion 10B.

The lower portion 10B is less rigid than the upper portion 10A and is configured to bend upon contact with plants. For example, the base material 11 of the lower portion 10B is made of cloth and has multiple slits extending in the vertical direction. On the other hand, the base material 11 of the upper portion 10A is made of a highly rigid steel plate.

The lower portion 10B is provided on the shielding walls 10 that intersect with the direction of travel of the device body 2 (i.e., the front and rear walls). On the other hand, the lower portion 10B is not provided on the shielding walls 10 that are parallel to the direction of travel of the device body 2 (i.e., the two side walls). On the two side walls, for example, the base material 11 is made of steel plate across the entire vertical direction.

[1-2. Effects]
According to the embodiment described above in detail, the following effects can be obtained.
(1a) The laser light irradiation space (i.e., the unwanted plant identification space) is surrounded by a shielding wall 10 having an inner surface made of a low-reflectivity material, thereby suppressing light reflection by liquid in the irradiation space. Furthermore, the shielding wall 10 can suppress the influence of external light, such as natural light, on the image. As a result, the recognition accuracy of unwanted plants is improved, allowing unwanted plants to be removed efficiently.

(1b) The light-blocking properties of the base material 11 prevent light from entering the shielding wall 10 from the outside, stabilizing the brightness of the laser light irradiated space. As a result, the accuracy of recognizing unwanted plants is improved.

(1c) By setting the wavelength of the laser light to between 400 nm and 550 nm, the laser light is less likely to be absorbed by the liquid. This increases the efficiency of removing unwanted plants.

(1d) The water injector 6 can suppress the generation of smoke caused by laser light irradiation. Furthermore, even if the sprayed water adheres to unwanted plants before removal, the shielding wall 10 can suppress the reflection of light.

2. Other Embodiments
Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take on various forms.

(2a) In the mobile weeding device of the above embodiment, the shielding wall does not necessarily have to have a base material and an inner layer. For example, the shielding wall may have only a base material made of a low-reflectivity material.

(2b) In the mobile weeding device of the above embodiment, the control device does not necessarily have to be attached to the device body. For example, the control device may be installed on farmland or in a facility away from farmland, and may be configured to communicate wirelessly with a camera, laser illuminator, etc.

(2c) The mobile weeding device of the above embodiment does not necessarily need to be equipped with lighting. If images that allow unwanted plants to be recognized can be obtained by taking in external light or adjusting the brightness of the camera, lighting can be omitted.

(2d) In the mobile weeding device of the above embodiment, the mode of movement of the device body is not limited to traveling. The mobile weeding device may move by flying, for example.

(2e) The function of one component in the above embodiments may be distributed among multiple components, or the functions of multiple components may be integrated into one component. Furthermore, part of the configuration of the above embodiments may be omitted. Furthermore, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. All aspects included within the technical concept identified by the wording of the claims are embodiments of the present disclosure.

1...Mobile weeding device, 2...Device body, 3...Laser irradiator, 4...Camera, 5...Lighting,
6...water injector, 7...monitoring sensor, 9...control device, 10...shielding wall,
10A... upper portion, 10B... lower portion, 11... substrate, 12... inner layer, 21... wheel,
91...image processing unit, 92...laser control unit, 93...ejection control unit, 94...database.

Claims (8)

a laser irradiator configured to irradiate a laser beam toward the plant from above the plant;
a camera configured to acquire an image of the plant taken from above;
a control device configured to identify the plant based on the image;
a shielding wall disposed so as to surround the laser light irradiation space;
an apparatus main body that holds the laser irradiator and the shielding wall and has a movement mechanism;
Equipped with
the inner surface of the shielding wall is made of a low-reflectivity material ,
the shielding wall has a front wall and a rear wall that are two walls that intersect with a traveling direction of the device body, and two side walls that are two walls that are parallel to the traveling direction,
The front wall and the rear wall each have a lower portion that is a portion within a certain range of distance from the ground on which the plants grow, and an upper portion that is a portion above the lower portion,
The mobile weeding device , wherein the lower portion has lower rigidity than the upper portion and is configured to bend upon contact with the plants . The mobile weeding device according to claim 1,
The mobile weeding device, wherein each of the two side walls has equal rigidity over the entire vertical direction. The mobile weeding device according to claim 1 or 2 ,
The shielding wall is
a substrate having a light-blocking property;
an inner layer made of the low-reflectivity material and disposed on the inner surface of the base material;
A mobile weeding device having: The mobile weeding device according to claim 1 or 2,
A mobile weeding device, wherein the low-reflectivity material is an anti-reflection film or an anti-reflection coating. The mobile weeding device according to claim 1 or 2,
The mobile weeding device, wherein the inner surface of the shielding wall is dark in color. The mobile weeding device according to claim 1 or 2,
A mobile weeding device, wherein the arithmetic mean roughness Ra of the inner surface of the shielding wall is 50 μm or more. The mobile weeding device according to claim 1 or 2,
A mobile weeding device, wherein the wavelength of the laser light is 400 nm or more and 550 nm or less. The mobile weeding device according to claim 1 or 2,
The mobile weeding device further comprises a water injector configured to inject water into the irradiation area of the laser light.