Apparatus for receiving light beams

The present invention relates to a method and system for distinguishing objects, especially for optical weed detection and elimination.

In many situations, it is necessary to distinguish different types of objects from each other. This issue is relevant in many different areas, such as technical production, data processing and mail distribution. However, distinguishing between objects in agriculture is of particular importance. For example, the ability to distinguish weeds from cultivated plants

173 490 is therefore important that even thinned weed populations continue to reduce moisture, exposure and nutritional value of crops, thereby significantly reducing harvest value. In addition, weeds can hinder agricultural machinery and hinder agricultural operations such as harvesting. The use of herbicides is a typical method of weed control. However, when using herbicides for diffuse weeds, most of the preparation is lost depositing in bare soil, and then the whole operation has no effect. Because herbicides are expensive, many growers try to save by using fewer of them. Then weeds with higher chemical resistance are not destroyed due to the application of an insufficient dose of herbicides. In addition, herbicides can have a very undesirable effect on the environment, e.g. by causing groundwater contamination or causing chemical burning of other plantations in neighboring fields during floods. Hence, there is a need to reduce both financial and environmental costs associated with the use of herbicides by selectively spraying only weeds.

Methods for optically distinguishing soil from plants are known. However, many of these methods use devices based on the use of sunlight to create a reflected image. Such devices can not work at night, and their work deteriorates when it is cloudy or even shaded.

For example, from US Pat. No. 5,144,767 an agricultural sprayer is known which is controlled by a device equipped with a sensor for determining irradiation in the near infrared wavelength range of the electromagnetic spectrum and a set of sensors for determining the radiation of the target area to be sprayed in the red and near infrared ranges. The controller that controls the individual spray nozzles of agricultural sprayer compares the measurements made by the sensors and compares the ratio of the measured values ​​to determine whether spraying of a specific target area should be turned on or off. This determination is made by observing tables of reflection coefficient values, or by performing calculations of nonlinear decision algorithms.

There are also known methods for optically distinguishing soil from plants using devices in which an artificial source of white light is used to create a reflected image. However, under natural conditions, i.e. in the sun, this artificial light source must compete with the sun, which is thicker times brighter and constantly changes its brightness and spectral distribution. Thus, known methods using a natural light source as well as using an artificial white light source do not convey a fully reliable wave description of objects from the field of view of the device, sufficient to eliminate individual weeds. In fact, the use of these methods is limited to little or no crops, where lack of precision can be tolerated. However, orchards, vineyards and flower beds require high accuracy in weed control. There is therefore a need to develop a device that provides accurate optical weed indication and ensures efficient weed control.

The method according to the invention is used to distinguish objects, in particular to determine the location of plants. According to the method, a beam of light reflected from the examined surface of the area is detected in two wave ranges of the electromagnetic spectrum, and the received electrical signal is analyzed and converted into the control signal of the interaction unit on the distinguished objects. This type of method is characterized by the fact that at least two monochromatic light sources move above the ground surface, and light beams of different wavelengths are supplied from the light sources. Beams of light are focused on the surface being tested, and beams emitted from light sources are subjected to modulation. After detecting the reflected light beam from the terrain surface, the electric signal parameter corresponding to the reflection coefficients of the different wavelengths contained in this reflected light beam is measured and analyzed to determine the type of surface examined.

It is preferred that during the modulation of the light beams, the phase of one of the light beams shifts relative to the phase of the other light beam. As a modulation of light beams it uses

173 490 multi-shade color modulation. During modulation, at least two monochromatic light sources are synchronized with the reflected light beam detection process.

Preferably, at least two beams of light are used with a first wavelength in the first time interval and with a second wavelength in the second time interval. The first and second time intervals are overlapping intervals, or are non-overlapping intervals.

During the process of analyzing the parameter of the electric signal corresponding to the reflection coefficients, specific actions are initiated towards the examined area of ​​the land, in particular, the herbicide is brought to the specific area where the plant is located. During the actions taken on existing plants, at least one portion of herbicide is fed to at least one plant different from the selected type.

The system according to the invention for distinguishing objects, in particular determining the position of plants, using beams of incident light and reflected from differentiated objects, is provided with reflected light detectors connected to the control central unit, which is connected to the set of interactions on differentiated objects. A system of this type is characterized in that it is provided with at least two monochromatic light sources connected to a lens for focusing light beams incident on a given surface of the land, which light beams have different wavelengths. The detector of the light beam reflected from the surface of the terrain is connected with the signal processing unit for analyzing the signal parameter corresponding to the coefficient of reflection of waves of different wavelengths contained in this beam and distinguishing the plant from the soil, which through the controller is connected to the set of impacts on plants different from the specific type of plants. In addition, monochromatic light sources and a reflected light detector are located on the ground-shifting unit for transverse surface analysis.

It is preferred that the light sources are light emitting diodes, lasers, or chromatic light sources with filters. Chromatic light sources are preferably incandescent light sources with filters, optionally fluorescent light sources with filters. It is preferred that the light sources are modulated light sources.

In a preferred arrangement of the system, a slotted plate is located in front of the reflected light detector, with a gap to limit the cross-sectional area of ​​the reflected light beam from a specific surface of the terrain. A detector lens is positioned in front of the slotted plate to focus the reflected light beam passing through the slit to the detector.

The output of the reflected light detector is connected to amplification circuits connected in series with the sampling-memory circuit, whose output is connected to the controller, for comparing the first reflection coefficient in the first specified time interval with the second reflection coefficient in the second specific time interval.

The plant interaction unit is connected to the control output of the controller through an actuating unit activated after detecting a plant different from the selected type. The plant interaction unit contains an electromagnetic valve connected to the herbicide supply terminated with a spray nozzle.

In an advantageous arrangement of the system, an electromagnetically controlled cultivator is connected to the control output of the controller through the actuating unit. A speed indicator is attached to the controller for the synchronization of the actuating unit.

It is preferred that the light sources are provided with phase shift means of the emitted light beams relative to each other. Preferably, the light sources are multi-shade modulated light sources. The sources of the phase-shifted light beams are offset from each other and the light sources are connected to the circuits of the analysis unit for synchronization.

In a different embodiment, the system according to the invention is characterized in that it is provided with a set of at least two monochromatic light sources with a first wavelength in the first time interval and with a second wavelength in the second time interval, connected to the lens assembly for focusing light beams with

173 490 of the first and second wavelength, falling on the surface of the immovable area with properties determined on the basis of radiation of the first and second wavelength reflected from this surface. An assembly for receiving a portion of radiation, with a first and second predetermined wavelength, reflected from said terrain surface is connected to a signal processing assembly representing the reflected portion of radiation, which via a controller is connected to a herbicide supply assembly to a selected terrain area. In addition, the radiation generating assembly and the radiation management assembly are movable relative to the terrain surface.

It is preferred that the radiation generating assembly comprises light emitting diodes. The radiation receiving unit is provided with a slot whose length is much greater than its width, and the longer side of the slot is perpendicular to the direction of travel of the radiation generating unit and the radiation directing unit.

The unit for receiving the reflected part of the radiation comprises a set of radiation detectors.

The controller comes with an indicator of the speed of movement of the generating units and directing radiation relative to the terrain surface.

In a second alternative, the system according to the invention is characterized in that it is provided with a first monochromatic light source with a first wavelength modulated by a first modulation signal of a given frequency directed towards a fixed stationary surface area of ​​the terrain and a second monochromatic light source with a second wavelength modulated a second modulating signal at a certain frequency, and directed at a specific fixed surface area. A light detector for detecting part of the light of the first wavelength and part of the light of the second wavelength, reflected from a specific area of ​​the terrain surface, is connected to the filter circuit to eliminate signals resulting from the action of sunlight, which has a frequency lower than the first and second frequencies modulated signal. The filter circuit output is connected to a signal processing unit for analyzing the detector output signal. In addition, the first and second monochrome light sources, the light detector, the filter circuit and the signal processing assembly are movable relative to the terrain surface.

It is preferred that the first monochromatic light source comprises a first light emitting diode and the second monochromatic light source includes a second light emitting diode. The filter circuit contains a capacitor connected in parallel with the coil. In addition, the filter circuit is connected through amplifying circuits with a phase detector, the second input of which is connected to the first and second modulated monochromatic light sources to receive one of the light source modulating signals.

The solution according to the invention provides a method and a device for distinguishing between different types of plants, enabling their identification and thus selective elimination or processing of individual plants. This type of solution significantly reduces the consumption of herbicides by precisely tracking individual plants to be eliminated. In addition, it can work in a variety of conditions, including cloudy, full sun, artificial lighting or even total darkness. In practice, the application of herbicides at night has some significant advantages. Lower temperatures allow longer and more efficient work at critical times during crop growth. In addition, the absence of the sun prolongs the effectiveness of certain herbicides. Higher relative humidity at night helps moisturize the leaves, which increases the effectiveness of herbicide use. The lack of wind often occurring after sunset eliminates the uncontrolled spread of the preparation. This significantly increases the efficiency in the use of herbicides to control weeds.

Labor and equipment costs depend on the speed at which the spraying vehicle moves through the field, orchard or vineyard. Using the traditional spraying method, the speed of the spraying vehicle may be limited by air turbulence arising as a result of apparatus movement and associated spraying over an excessive area.

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In the weeding device according to the invention, a spray nozzle directed at the plant is used which is sprayed with a narrow and intense stream. Such a spray cone significantly eliminates spraying on an excessive area and allows a much higher vehicle speed.

The solution according to the invention brings farmers closer to the goal of not passing any weed, not overdosing herbicides with none of the weeds, and little or no herbicide buildup in the soil. Combined benefits include reduced costs by reducing the amount of herbicides used, reduced maintenance costs, reduced equipment costs, improved weed control, and significantly reduced crop and employee exposure to herbicides.

The subject of the invention is explained in the examples of the drawing, in which Fig. 1 is a graph representing light reflection curves from plants and soil, for different wavelengths, Fig. 2 - diagram of the first variant of the weeding system, Fig. 3 - effect of the slotted plate for weed detection, Fig. 4 - graphs of light waves for two different wavelengths before and after reflection from the ground, Fig. 5 - the second variant of the weeding system according to the invention, Figs. 6A and 6B show typical spacing required for seedbed cultivation of plants, and Fig. 7 shows the third variant of the weeding system according to the invention.

Radiation is reflected or vice versa, absorbed by surfaces, depending on the properties of these surfaces. In plants, radiation with a wavelength of 380 to 700 nanometers is strongly absorbed by chlorophyll in plants, while near-infrared wavelengths, i.e. 700 to 1000 nanometers, are strongly reflected. Other substances, such as soil, absorb much more radiation for many of these wavelengths. In fig. 1 a graph is shown on which the wavelength from 400 to about 1000 nanometers are laid out on the horizontal axis, and the reflection coefficient expressed as a percentage is set on the vertical axis. From the graphs in Fig. 1, it follows that, for example, for a wavelength of 750 nanometers, a typical plant represented by curve 100 is easy to distinguish from the soil represented by curve 101, because the plant reflects a greater percentage of light than the soil. It should be noted that the reflection coefficient for the plant has its minimum for a wavelength of about 670 nanometers, and it is then smaller than the reflection coefficient for the soil. In the system according to the invention, to obtain reflected light, instead of sunlight or an artificial white light source, a set of monochromatic light sources is used. The optimal light source for distinguishing the plant from the soil, as shown in fig. 1, has a wavelength of about 670 nanometers, which corresponds to the upper red region, and a wavelength of 720 to 750 nanometers, which corresponds to the infrared region.

Figure 2 shows a first variant of the system according to the invention, which can be used as an intelligent weeding device. In this system variant, two monochromatic light sources 201 and 202 are used. The first monochromatic light source 201 emits a light beam 203 with a wavelength of 750 nanometers', while the second monochromatic light source 202 emits a light beam 204 with a wavelength of 670 nanometers. Light sources 201 and 202 are typical commercially available LEDs, made of gallium arsenide, gallium arsenide phosphide or aluminum gallium arsenide, which provide high stability and low cost of monochromatic light sources. Other light sources are preferably lasers or broadband light sources with filters.

If the diodes 201 and 202, which are light sources, are turned on only with direct current and directed to a specific surface of the area 206, reflections of sunlight from the surface area of ​​the area 206 can significantly deteriorate or even prevent the operation of the system. Hence, according to the invention, the current of diodes 201 and 202 is selectively modulated. In a preferred solution, the modulation consists in the fact that diodes 201 and 202 are controlled by the current with the highest possible frequency within the forced band, while remaining compatible with other elements of the system. In the example shown, the diodes 201 and 202 are modulated at a frequency of 455 kHz. It should be noted that at

173 By increasing the frequency, it is possible to provide the user with a larger portion of information over a certain period of time, thereby providing more sensitive measurements.

The light beams 203 and 204 emitted from the diodes 201 and 202, respectively, are focused by the lens of the emitter 205 on a particular surface of the area 206, which may contain a plant, soil, or both soil and plant. Light beams 207, reflected from the terrain surface 206, are detected by the photodetector 2010 after passing through the gap 209A in the slot plate 209. The light detected by photodetector 210 contains different ratios of the content of the waves with different wavelengths of monochromatic light, depending on whether the light beams 203 and 204 were reflected by the plant or by the soil.

The total light reflected from a surface, such as a plant leaf, has been found to be proportional to the entire reflection area. For example, referring to Fig. 3, if the diameter d of the weed 300 is 0.635 cm (1/4 inch, and therefore has an area of ​​π / 64 inch²), and the diameter D of the entire reflection area 302 is 2.54 cm (1 inch, so the surface is π! 4 inch)²), the weed makes up 1/16 of the entire reflecting area and thus is only 1/16 to the total reflected light. However, if the light reflected from a weed of the same size is limited by a gap 301, which is one 2.54 cm (1 inch) long, but only 0.635 cm (1/4 inch) wide, then the light reflected from the weed is 1 / 4 of the new total area, i.e. the gap area 301. Hence, in this example, the reflected light signal strength quadruples. It follows that by introducing a slotted plate 209 which includes a slit 209A having a length that is significantly greater than the slot width, the solution according to the invention replaces the traditional quadratic function of the area, i.e.²/ ^, a linear function, i.e. D / d.

To ensure proper arrangement between the detector lens 208, the slot 209A of the slot plate 209 and the photodetector 210, one example of the invention is provided with a gap 209A, which is much smaller than the detector lens 208. Furthermore, this embodiment of the invention provides an image of reflected beams 207 by detector lens 208, which is much smaller than the size of photodetector 210. In this way, no offset between these three elements is critical as long as it remains within the defined limits set by the slot size 209A, the size of the photodetector 210 and the distance of the photodetector 210 from the slot 209A, and other parameters. It has been found that the increasing size of photodetector 210 produces an undesirable increase in its capacity. Hence, according to the invention, the photodetector 210 is only slightly larger than the gap 209A, to minimize its capacity. However, this capacity is buffered by a cascade amplifier circuit providing the same bandwidth as for smaller 210 photo detectors having a smaller capacity.

The photodetector 210 converts the light energy of the beams 207 of reflected light into low-level electrical signals, corresponding to the color designation of the wavelength reflected from the object (s) in the field of view. For example, Figure 4 shows waveform envelopes 400 that have a length of 750 nanometers and waveform envelopes 670 nanometers. Diodes 201 and 202 (fig. 2) they are modulated by a signal with the same pulse repetition period, which creates identical wave envelopes.

However, as shown in Fig. 4, the modulation of one diode providing wave envelope 400 is approximately 30-45 ° in phase with the modulation of the other diode providing wave envelope 401. After the reflection of light beams 203 and 204 from the surface of the area 206 , the photodetector 210 provides current, the current phase being a function depending on the amount of light associated with each of the wavelengths. For example, the waveform 400A represents the current supplied by the photodetector after the 400 envelope has been detected. Similarly, the waveform 401A represents the current supplied by the photodetector 210 after the 401 envelope has been detected. Note that the 401A is shifted about 90 ° in phase with the wave 400A. This phase shift is caused by the larger capacity of the second diode 202, which provides the wave envelope 401, while the capacity of the first diode 201 provides the wave envelope 400, causing a delay in photoemission, i.e. the delay of the emitter current relative to the currently emitted light. Photodetector 210 adds 400A and 401A, and provides wave 402 that is shifted

173 490 in phase about 45 °. Hence, the wave phase shift 402 is a function of the relative wave phases 400A and 401A, but also the difference of delays brought by different emitters. After the light beams 203 and 204 are reflected from the terrain surface 206, the resulting summed waves 402 vary in amplitude, which is not shown in Figure 4, depending on whether the 750 nm or 670 nm wavelength is absorbed or reflected. This amplitude difference is another source of phase shift in the detector current 402. This variable phase shift carries the desired information about the spectral reflection coefficient.

Tuned circuit 213 containing coil 211 and capacitor 212, connected in series with photodetector 210, operates in resonance due to excitations from photodetector 210. The output waveform of tuned circuit 213 is therefore essentially sinusoidal. The tuned circuit 213 rejects everything that is not sinusoidal and does not have a selected frequency, i.e. unwanted harmonics. The accepted sine wave is then fed to circuit assembly 214, which usually includes amplifiers 215A and 215B, and tuned circuit 215.

The amplification circuit assembly 214 provides very high amplification of the modulated signals provided by the reflected light beams 207. At the same time, the coil 211 in the tuned circuit discharges the unwanted constant component of the photodetector 210 output signal, resulting from the action of the sun, directly to the ground. Preferably, automatic frequency control is used, which is not shown, to ensure that tuned circuit 215 rejects as much of the out-of-band signal as possible, thereby minimizing the effect of sunlight reflected from the terrain surface 206 on the modulated light beam 207 reflected from the same surface. In addition, an automatic gain control circuit 230 is used to provide the widest dynamic range possible for 215A and 215B amplifiers. The amplifier circuit assembly 215B trims the amplified sine wave to deliver a specific rectangular waveform to the phase 217 detector. The phase 217 detector receives the rectangular signal from circuit 214 and multiplies this signal with the signal from diode 201. Thus, the phase 217 detector determines the phase shift of the output wave of the circuit 214 relative to the original phase of the signal from diode 201.

To extend the system's ability to process information faster, the sampling-memory circuit 218 is coupled to the phase detector 217. The output of the sampling-memory circuit 218 is connected to the negative input of comparator 219. The input of the sampling-memory circuit 218 is connected to the negative input of the transducer 220 and to the analog-to-digital converter 223. Comparator 219 compares the instantaneous value taken from the sampling-memory circuit 218 with the previous sample from that circuit, and thus provides an indication of the detection of a momentary change in the analog signal detected by photodetector 210, a positive or negative change. The output signal of comparator 219 is fed to the controller 221, so it indicates the direction of change of individual color markings in the light wave spectrum. Hence, comparator 219 provides the controller 221 with information that enables the controller 21 to determine the phase and phase shift of the sum of reflected radiation relative to the initial modulated beams 203 and 204.

The ratio comparator 220 compares the output from the DAC 222 with the instantaneous value of the output of the phase 217 detector. The reference voltage threshold is manually set for various types of soil mineral substrate and partially decomposed organic matter. In another preferred example, the threshold reference voltage is set automatically via the appropriate controller software 221 and DAC 222. In this way, the controller 221 provides a constant analysis of the substrate material provided to the ratio comparator 220 by a D / A converter 222. The ratio comparator 220 has a binary output that sets depending on whether the ratio of the detected wavelength in the field of view exceeds the reference value for substrate. According to the invention, the controller 221 analyzes the signals provided by comparators 219 and 220, and determines whether weed has been detected in a particular area of ​​the terrain surface 206. Although only a single is shown

173 490 photodetector 210, system 200 in a preferred embodiment is equipped with a set of photodetectors 210 and appropriate signal processing circuits.

If a weed is detected, controller 221 launches a device to eliminate this weed. Controller 221 provides a control signal (typically high level for transistor 228 as shown in Figure 2) to the base of NPN 228 bipolar transistor if weed has been detected. Turning transistor 228 then opens the solenoid valve 227 that releases the herbicide stream 226 through nozzle 229.

To reduce interference with plant photodetection, the herbicide 226 is not sprayed at the same time as the photodetector 210 receives the reflected light beams 207 from the surface of the terrain 206. Thus, the spray nozzle 229 is located off the terrain of the vehicle 206, i.e. outside the vehicle field of view of photodetector 210.

To correctly direct the herbicide stream 226 to the surface of the terrain 206, the controller 221 delays the signal fed to transistor 228 relative to the vehicle's V speed, which is provided by the speed indicator 224, and the stream X shift length relative to the weed while the weed is detected. The delay time T is only T = X / V, where X is the distance in meters, V is the speed in meters per second, and the time is expressed in seconds. Various types of vehicle speed indicators are acceptable, including radar indicators using the Doppler effect. In the solution according to the invention, the possible vehicle speeds are greater than 16 km per hour, because the system provides a wide margin of computing power, with the possibility of treating the controller with megahertz systems.

The operating software of the 221 controller is stored in permanent memory. This software can be parameterized quickly and easily for different types of crops and different types of weeds. For example, if the photodetector 210 has detected weed at three consecutive moments of time, and the neighboring photodetectors have noticed the same weed at two of these three moments, then the solenoid valves on each side of valve 227 (which is properly switched) will be turned on for the expected high weed density.

In the preferred example according to the invention, the nozzles 229 are directed towards the ground. Each nozzle 229 facing surface 206 is connected to a respective photodetector 210. Controller 221 controls each valve 227 through signals delivered to the base of each transistor 228. Transistor 228 is controlled to optimize the switching speed of solenoid valve 227. This solenoid valve 227 typically closes and opens in 5-10 ms. Nozzles 229 emit short beams of the herbicide directly on the body of the plant, thereby avoiding spraying on the adjacent area. In an application of the invention, the light detector can be used to detect weeds some distance from the valve through which the herbicide is to be injected. This application is particularly useful in destroying weeds along highways. One of the problems with controlling weeds along the road is that the herbicide-containing vehicle must remain on the road while the weeds grow on the sides or off the road. According to the invention, the light detector detects weeds in a certain off-road position. The nozzle through which the herbicide is injected is then positioned at a right angle so that the released portions of the herbicide are aimed at the weed area. The herbicide is therefore injected at a selected angle and for a selected period of time to ensure that the area of ​​land where the weed grows will be covered with herbicide, while adjacent areas will most likely not be covered with herbicide. The calculation of the angle and pressure required to inject the herbicide into the relevant off-road area is made using known liquid flow equations and dynamics equations.

Directing the herbicide liquid to targets located at a long distance (over 1 meter) requires a dense herbicide stream with sufficient mass. If the dense herbicide stream is on and in continuous operation while weeds are present in the optical field of view, more herbicide is sprayed than necessary.

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To reduce the amount of herbicide while maintaining the same trajectory, the jet has pulse width modulation. This modulation cycle becomes the equivalent of setting flow parameters without changing the pressure and the dimensions of the nozzle.

System 200 is preferably used as a weeding system moving at a higher speed through rows of plants, compared to known weeding devices. The cost of service and equipment basically depends on the speed at which this apparatus can move through, for example, an orchard or vineyard. Using traditional weeding methods, the speed at which the vehicle can move is limited by the turbulence of air resulting from the movement of the equipment and the associated spraying over too large an area. The spray nozzle 229 directs a very narrow compact conical stream. The system according to the invention considerably eliminates the spraying on too large an area and allows much higher vehicle speeds.

In the second example of the invention shown in Fig. 5, the light beams 203 and 204 are isolated from sunlight. In detail, being monochrome light sources, diodes 201 and 202 are sequentially turned on and off at a high frequency, for example 1 MHz. The amplifier 501 stores the voltage generated by the photodetector 210 and supplies the amplified voltage to the 502 memory-sampling circuits. The memory-sampling circuits 502 are gated by the same clock signal that controls the diodes 201 and 202. In this way, one memory-sampling circuit is switched on at the same time as the first diode 201, the other memory-sampling circuit is switched on when it is not turned on. neither the first nor the second diode 201,202. Hence, one memory-sampling circuit provides an output signal corresponding to light at 670 nm plus sun light, the other memory-sampling circuit represents light at 750 nm plus sun light, and the last sampling-memory circuit represents only the light of the sun.

The 503 amplifiers take the signals generated by the sun, outputting only signals representing light with a wavelength of 670 and 750 nm. The 504 amplifier sums the output signals from the 503 amplifiers. The output signals are also sent to the 510 analog-digital converter through 508 analog gates. The 510 analog-digital converter is connected directly to the 221 controller. The output signal of the memory-sampling circuit 505 is fed to the negative input of the comparator 507. Comparator 506 provides an output signal indicating changes in each of the individual color markings in the light spectrum (equivalent to comparator 219 in Fig. 2). The comparator 506 provides information to the controller 221 that allows the controller 221 to determine the magnitude and direction of the phase shift of the total reflected radiation relative to the light beam 203.

Comparator 507 compares the output signal of the 509 D / A converter with the instantaneous value of the 504 amplifier output signal. The 509 D / A converter output (equivalent of the 222 D / A converter from Fig. 2) is set to compensate for mineral soil and partially decomposed organic matter . Hence, the output of comparator 507 varies depending on whether the ratio of the detected wavelengths of different wavelengths exceeds the reference value for the substrate. Controller 221 analyzes the signals provided by comparators 506 and 507 to determine if weed has been detected.

It should be noted that in other preferred examples of the system of the invention, instead of herbicides for removing weeds or unwanted plants, a mechanical device such as a rotary cultivator may be used. Figures 6A and 6B show typical spacing between crop beds. As shown in Fig. 6A, flower beds 605 are typically grown in two rows at the top of flower beds 604. The spacing 600 between these two rows is approximately 15-30 cm, while the spacing between center points of beds 604 is approximately 60-70 cm. 603 tires, e.g. a tractor not shown, include two beds 604 and are spaced 608 apart, approximately 120-250 cm. Rows 606, shown in Fig. 6B, are densely overgrown with plants to ensure maximum production. However, especially

173 490 during optimal growth conditions, too many plants grow in a row too close to each other, then weeding must take place to ensure appropriate development conditions for each plant. In particular, plants 607 must be removed to provide a distance 602 of about 15-30 cm between plants 605 that are intended to be left behind. Hence, the weeding system shown in Fig. 2 or in Fig. 5 it is equipped with an electromagnetically controlled hoe instead of an electromagnetic valve and provides cutting, in addition to the possibility of weeding.

In the next example of the invention shown in Fig. 7, the intelligent system from weeding 700 distinguishes different weed and crop properties based on the spectral reflection coefficient, i.e. the size, shape and position of the plant. The weeding system 700 uses a set of monochromatic light sources 701-1, 701-2, 701-3, 701-N, where N is the total number of light sources, each light source having a different wavelength. In this variant, the microcontroller 221, in addition to the functions described in relation to Figs. 2 and 5, analyzes the following parameters: size of individual leaves, shape of individual leaves, position of the plant relative to the designed row, and row spacing.

Different wavelengths of light sources 701-1 - 701-N are multi-shade modulated, with each wavelength corresponding to a particular modulation frequency. Beams of light 702 are reflected from surface 206 in the field of view of photodetector 210 as described with reference to Fig. 2. Tuned circuit 713, consisting of coil 711 and capacitor 712, has a substantially wider band than tuned circuit 213 of Fig. 2 , to accept a wide range of modulated frequencies. The 703 amplifier provides adequate gain and impedance, the 704 filters are narrowband filters, and each filter is tuned to the appropriate modulation frequency. The detectors 705 convert the output signals of the filter 704 into constant signals proportional to the content of different wavelengths in the reflected light beams 207. The 707 analog transmission gates multiplex the voltage levels to a high speed 223 analog-to-digital converter. The transducer 223 then drives the controller 221, which activates the relay 228 and the electromagnetically controlled cultivator 708.

In a system according to the invention not illustrated in the drawing, the weeding device as shown in Figures 2.5 or 7 may be carried by one person, either in the form of a hand-held device or in the form of light equipment. In this variant, the optical system, e.g. diodes 201, 202, emitter lens 205, detector lens 208, slotted plate 209 and photodetector 210 of Fig. 2, are connected to the spray rod by a fiber optic cable. The bar also includes an accelerometer for determining the speed and direction of travel of the bar.

The weed control system according to the invention provides a much more efficient method for eliminating weeds from crop plants. For example, in a typical orchard there are essentially three weed control operations, some of the operations are carried out two or more times a year depending on the crop and geographical area. During the first operation in early spring, from 90 to 152 cm wide, the row is sprayed with a thick layer of pre-emergence herbicide. The mixing ratio is high and coverage is particularly high, as not taking the opportunity to completely annihilate the weeds at this point means increased expenditure as the weeds mature. In addition, the herbicide mixture often contains a post-emergence herbicide for attacking one-year-old weeds that have just emerged and multi-season weeds that have remained from the previous season. For the operation you need a driver, a spray mounted on the tractor, and a large amount of a very expensive herbicide. During the second operation, in the summer months, the areas between the sprayed rows, which are typically 4.5-5.2 meters wide, are cut or plowed. For this operation you also need a driver and probably a different tractor than the one used for spraying. Typically, this operation is repeated two to four times during the growth period. Finally, in the third operation, the post-emergence herbicide is injected onto the weeds that have avoided winter pre-emergence destruction in the sprayed rows. The tractor moves

177 490 along the middle groove, while two workers spray weeds in rows, one worker in each of the two grooves adjacent to the middle groove. A tractor is mounted on the tractor, which sprayes with a stream of herbicide with a high concentration intended for the destruction of fully grown healthy weeds. Alternatively, portable hand sprinklers are moved by employees, and individual weeds are identified and destroyed. This operation is also carried out two or three times a year.

According to the invention, spraying and plowing operations can be carried out simultaneously. Then one tractor for the whole season is enough, instead of three. An intelligent weeding system is mounted in the front of the tractor in one application. A typical rotary or flail device is then mounted on the rear of the tractor. In this way, the winter pre-emergence treatment can be made with some of the herbicides used in traditional methods, or in some cases completely eliminated, because the weed control system selectively and precisely doses the herbicide used, and thus is much more effective later, during the growth period. In addition, as already mentioned, the whole operation is carried out by one driver and one tractor. Two different types of spraying can also be carried out simultaneously. In particular, the pre-emergence herbicide directed at the whole area of ​​the earth can be used in a traditional manner, while the post-emergence herbicide directed only at selected plants can be used in accordance with the invention.

In addition, the weed control system of the invention can operate in a variety of conditions, including bright sunlight, wind, artificial lighting, or total darkness, thereby enabling 24-hour operation. When spraying fields with herbicides at night, you get some benefits because cooler conditions allow you to work longer and more effectively at peak times of the season. In particular, greater relative humidity at night promotes leaf soaking, which increases the effectiveness of the herbicidal material, and the lack of wind after sunset prevents spraying of too much area. Thus, in addition to significantly reducing the cost of herbicides associated with weed control, the inventive solution, having the ability to work at night, provides additional benefits.

The solution according to the invention minimizes or even eliminates the use of pre-emergence herbicides in favor of cheaper and more ecological post-emergence herbicides. Post-emergent herbicides are applied to individual plants and penetrate the plants through their leaves. Pre-emergence herbicides are introduced into the soil and prevent grain germination. Pre-emergence herbicides are designed to withstand a long time in the soil and are therefore a threat to the environment. In addition, pre-emergence herbicides are generally more expensive than post-emergence herbicides. The solution according to the invention reduces the costs of eliminating weeds and at the same time reduces the environmental burden.

In summary, the precision of the weed control system of the invention ensures that no weed is overlooked, that no weed receives more herbicide than is needed, and that the herbicides are not injected into the soil. As a result, such a weed control system reduces the number of servicing employees, the cost of equipment operation, reduces herbicide costs, significantly improves weed control, and significantly reduces the exposure of employees and cultivated plants to herbicides.

The system according to the invention described in relation to spraying with herbicides can be used in combination with fertilizers, fungicides and insecticides. The term light is not limited to visible light, but refers to any radiation of the appropriate wavelength.

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WEED

UP Department of Publications. Circulation of 90 copies

Price PLN 4.00