System and method for illuminating with UVC radiation plants on the ground, and use of the system

Abstract

A system for illuminating with UVC radiation plants on a ground, the system comprising: a platform which comprises a mounting frame (6) and is movable over the plants and the ground and towards a first direction (F); one or more UVC projectors (3) mounted on the mounting frame (6) and configured to generate UVC radiation and collimate and project it downwards towards the plants and the ground; two or more reflector assemblies (7) which are mounted on the platform and arranged below the one or more UVC projectors (3) and between the mounting frame (6) and the ground, and are configured to reflect non-collimated radiation which is emitted by the one or more UVC projectors (3) has a directional component towards a second direction (A) which is perpendicular to the first direction (F). Also, a use of the system, and a method.

Description

[0001] SYSTEM AND METHOD FOR ILLUMINATING WITH UVC RADIATION PLANTS ON THE GROUND, AND USE OF THE SYSTEM

[0002] TECHNICAL FIELD

[0003] The present invention relates to a system for illuminating with UVC (Ultraviolet-C) radiation plants on the ground. The present invention also relates to a method for treating with UVC radiation the plants on the ground. Also, the present invention relates to a use of the system for protecting horticultural crops or plants from fungi. The system may also be a device, or apparatus or vehicle or cart. A preferred embodiment of the system is a safe UVC fungicide. Also, some preferred embodiments of the present invention concern a method and an apparatus to protect horticultural crops from fungi by using UVC collimated light and leave stirring by turbulent airflows.

[0004] BACKGROUND

[0005] Chemical pesticides are harmful for human health and the environment.

[0006] Protecting crops from fungal diseases is very important in horticulture to guarantee yield and quality of produce. When growing organic crops, not using chemical fungicides, efficient fungicide options for vegetable growers are reduced.

[0007] Irradiating crops with UVC light is a proven fungicide method in glass houses and it is being tested in its outdoors application on high value crops like strawberry or lettuce, showing high protection efficacy against powdery mildew and oidium.

[0008] Outdoors usage of UVC radiation as a fungicide treatment for horticultural crops poses significant risks on human and animal health. Accidental exposure to UVC radiation may harm the skin and eyesight.

[0009] At the same time, it has been challenging to find a way to assure that the applied UVC radiation penetrates between the leaves and into the meristem of crop plants and that it also impinges on the lower side of leaves. In previous art the UVC radiation coming from Hg low pressure tubes is used with simple flat reflectors generating a diffuse radiation pattern.

[0010] Usually, the tubes and reflectors are mounted inside a tunnel structure surrounding the crops on its top and sides. This arrangement allows an important proportion of the UVC radiation to leak through the front and back openings of the tunnel.

[0011] A countermeasure against this potentially harming UVC radiation leakage has been to cover the front and back opening of the tunnels with skirts made of hanging strips or rods of soft UVC blocking materials. This solution has the inconvenience of disturbing the crops by physical contact, even potentially promoting the transmission of infections, and it delivers a random protection, because the skirts may eventually allow openings during its physical interaction with the crop canopy, allowing for some UVC radiation to leak.

[0012] Also, the fact of having a tunnel per crop bed, with UVC tubes mounted under the hood and illuminating downwards and UVC tubes mounted at the sides of the tunnel and illuminating inwards, creates an uneven distribution of the UVC treatment when having several rows of crops per bed, which is the usual case in horticulture. This can be solved if the device is configured with one tunnel per row, but then the thickness of the UVC luminaries at both sides of each tunnel is a restriction in the row distribution within the bed, significantly reducing the available free space between rows.

[0013] Because the emission pattern of the combination of discharge tubes and flat reflectors yields an approximately Lambertian pattern, the UVC irradiance diminishes with the square of the distance between plants and illuminators. Therefore, even if light could reach the different parts of the plant, it will reach the surfaces at different irradiance levels.

[0014] It is also the common practice to mount the UVC tubes along the crop rows, in the forward moving direction of the vehicle applying the treatment.

[0015] Low pressure Hg lamps are typically used to provide the required power, efficiency and cost. UVC LEDs are also available, but its conversion efficiencies and cost per Watt may be worse than that of Hg low pressure lamps. The literature shows that dosages around 200 J / m2for the leaf surface may be used for an effective treatment against oidium, powdery mildew and other fungal diseases.

[0016] At the same time, it has been discovered that UVC fungicide action may be most effective when executed nocturnally and that optimal results may be obtained when the treatment is done at least four hours before dawn, to avoid the healing effect of diurnal light on fungi DNA. So, to destroy fungi, the UVC dose of 200 J / m2can preferably be applied after sunset and at least four hours before dawn, limiting the operational time to five hours in the summer solstice in Spain and to just three hours in the Netherlands.

[0017] This means that if high productivity is required the irradiance UVC levels on leave surface should preferably be relatively high. For instance, if the vehicle moves at 2 m / s, the UVC irradiance on the crop should preferably be 400 W / m2. If the vehicle covers one crop bed, typically 2 meters wide, this implies a total UVC irradiance of 800 W / m2is preferably required.

[0018] UVC irradiance to consumption power efficiency of different types of Hg lamps ranges between 30% to 40%, depending on configuration, diameter and length. Longer and thicker discharge tubes being typically more efficient than short and thin ones.

[0019] Hence, it may be understood that providing for a way to treat plants with UVC radiation in a safe and efficient manner, is needed.

[0020] DESCRIPTION OF THE INVENTION

[0021] The present invention aims at solving the problem of how achieve treating plants, e.g. crops, on the ground with UVC radiation in an efficient and safe manner, so that the UVC radiation is advantageously largely confined to the ground region where the plants are, and its leakage to the surrounding environment is avoided. Also, at least some embodiments of the present invention may further advantageously allow a uniform treatment of the plants, and in manner that is not complex nor expensive to implement.

[0022] The present invention is a first aspect concerns a system for illuminating with UVC radiation plants on a ground, the system comprising: a platform which comprises a mounting frame and is movable over the plants and the ground and towards a first direction; one or more UVC projectors mounted on the mounting frame and configured to generate UVC radiation and collimate and project it downwards towards the plants and the ground; two or more reflector assemblies which are mounted on the platform and arranged below the one or more UVC projectors and between the mounting frame and the ground, and are configured to reflect at non-collimated radiation which is emitted by the one or more UVC projectors and has has a directional component towards a second direction which is perpendicular to the first direction. The system may alternatively be an apparatus or a device.

[0023] It may be understood that during an operation of the system part of the generated UVC radiation is collimated and projected by the UVC projectors downwards towards the grounds and the plants, and another part of the generated UVC radiation is emitted by the UVC projectors at least partly towards the second direction and reflected by the reflector assemblies. Also, it may be understood that when in this disclosure reference is made to a radiation emitted towards a certain direction, it should be understood that this means that at least part, i.e. a respective directional component, of that radiation is directed towards said certain direction. Hence, it may also be understood that the one or more projectors advantageously allow for projecting at least some of of the generated UVC radiation downwards towards the ground and the plants. Also, it may be understood that the reflector assemblies may advantageously allow for avoiding the leakage of any UVC radiation part that is emitted towards the second direction, and for back reflecting that radiation part so that the radiation is advantageously confined within a region where the treated plants under the moving platform are located, and for treating said plants more uniformly and efficiently. Avoiding the leakage of the UVC radiation in the second direction improves the safety of the system, reducing the risk for the humans or animals that may be located around the platform during the system’s use.

[0024] In a preferred embodiment the reflector assemblies comprise lateral reflectors which are arranged substantially parallel to the first direction. Preferably the lateral reflectors are substantially parallel to each other, and more preferably extend from the platform and the mounting frame downwards towards the ground. This configuration allows for efficiently blocking the radiation that is emitted towards the second direction.

[0025] In a preferred embodiment, the UVC projectors are configured to project at least part of the UVC radiation downwards and perpendicularly to the ground. This may advantageously allow for further optimizing the efficiency of the treatment of the plants that may be under the UVC projectors during an operation of the system and the movement of the platform.

[0026] In a preferred embodiment, the one or more reflector assemblies further comprise bottom reflectors configured to reflect upwards towards a bottom side of leaves of the plants collimated UVC radiation emitted the one or more UVC projectors. Preferably said bottom reflectors are bottom angled reflectors. These bottom reflectors may advantageously be used for further optimizing the uniformity and efficiency of the UVC treatment of the plants.

[0027] In a preferred embodiment, the one or more reflector assemblies comprise at least one single reflector assembly and / or at least one double reflector assembly, wherein each of the at least one single reflector assemblies comprises a corresponding lateral reflector and a corresponding bottom reflector located on a side of the respective side reflector, and wherein each of the at least one double reflector assemblies comprises a corresponding lateral reflector and two corresponding bottom reflectors, each of which is located on a respective side of the corresponding lateral reflector. The single reflector assemblies may preferably be used on two lateral sides of the platform, e.g. on the right side and the left side of the platform, to advantageously block the leakage of radiation through said sides, and the doble reflector assemblies may be positioned between adjacent UVC projectors arranged along the second direction, in the optional case the system comprise multiple UVC projectors arranged in such manner. In the latter case, the double reflector assemblies may advantageously further improve the efficiency with which the radiation produced by the UVC projectors is utilized for the treatment of the plants.

[0028] In a preferred embodiment each of the one or more UVC projectors comprise a corresponding UVC lamp, wherein preferably the UVC lamp has a tubular shape, and more preferably is arranged lengthwise along the second direction. The use of UVC tubular lamps may facilitate the fabricability of the system, and may contribute to reducing its cost without compromising its efficiency.

[0029] In a preferred embodiment each of the one or more UVC projectors comprise corresponding collimating optics, preferably a corresponding collimating reflector, more preferably a corresponding compound parabolic concentrator. The optional use of a collimating reflector, especially a compound parabolic concentrator (CVC), may facilitate the fabricability of the system, and may allow for constraining within a certain angle theta, the radiation that is projected by the UVC projector downwards towards the ground and in a direction perpendicular to the second direction.

[0030] In a preferred embodiment which is according to the previous one, along the first direction the corresponding collimating reflector is configured to constrain with an angle theta (0) the UVC radiation emitted by the UVC projector. This advantageously improves the efficiency with which the UVC radiation is utilized for the treatment of the plants, and may also further improve the safety of the system since it can help to avoid or greatly reduce the leakage of radiation along the direction (i.e. the first radiation) of the movement of the platform.

[0031] In a preferred embodiment which is according to the previous one, the system further comprises a protective cover that is on the platform and is configured to block specular UVC radiation reflected by the ground under the one or more UVC projectors during an operation of the system, wherein preferably the protective cover has a length that is at least equal to 2*tan(theta)*h, wherein h is a height, above the ground, at which the protective cover is. This protective cover may advantageously further improve the safety of the system by blocking the leakage of UVC radiation to the environment.

[0032] In a preferred embodiment, the UVC radiation has an emission peak at 254 nm. UV radiation (i.e. UV light) of a wavelength of 254 nm may advantageously exhibit good germicidal and fungicidal action.

[0033] In a preferred embodiment the movable platform is any of a cart, a vehicle, a rover, a trailer, a tractor trailer, a tractor cart, an autonomous or remotely operated rover or an autonomous or remotely operated vehicle. In the optional case that the platform is an autonomous or remotely operated vehicle or rover, this may further improve its safety by avoiding the need for a user being on or close to the system during the system’s operation.

[0034] In a preferred embodiment the one or more UVC projectors form an array of UVC projectors. This may advantageously allow for increasing the surface area of the ground that may be covered and treated by the system at any given moment, and may allow for further optimizing the uniformity which the plants can be treated with the system. In a preferred embodiment each of the one or more UVC projectors comprises a corresponding UVC lamp tube and is configured to emit the UVC radiation circumscribed within a maximum angle theta in the direction perpendicular to the lamp tube, wherein the angle theta is measured with respect to a direction that is perpendicular to the ground. In the latter case, the leakage of UVC radiation is advantageously further avoided, further improving the safety of the system.

[0035] In a preferred embodiment, the system further comprises height adjusting means configured to adjust the height of two or more reflector assemblies, and preferably the corresponding heights of the one or more UVC projectors (3) and / / or of the mounting frame (6), with respect to the ground. In the latter case, the height adjusting means may advantageously allow for ensuring an optimum operation of the system under different terrain environments and for various types of plants or crops that need UVC treatment.

[0036] In a preferred embodiment, the system further comprises one or more air blowers mounted on the platform and configured to blow air downwards towards the ground and the plants. Preferably the one or more air blowers is / are configured to blow the air non-perpendicularly, i.e. diagonally, to the ground, more preferably the one or more air blowers being in front of and / or before the UVC projectors in the first direction. The air blowers may advantageously stir the treated plants and the leaves of the plants, for improving the penetration of the UVC direction towards the bottom of the plants, and for achieving a more uniform and optimized treatment of the plants.

[0037] In a preferred embodiment, the system further comprises at least one camera system, preferably the system comprising one or more cameras, and / or a LIDAR. The optional incorporation in the system of such a camera system, may further allow the system offering advanced functionalities, such the identification of the plants, providing and utilizing information related to the size, shape or volume of the plants, or analyzing the terrain for the purpose of adjusting one or more operational parameters of the system.

[0038] In a preferred embodiment, the system further comprises a control system configured to perform any of the following: control a power of the UVC lamp; adjust a moving speed (i.e. movement speed or velocity) of the platform; identify the species of the plants; obtain volume and / or height information of the plants; control a height of any of the mirror assemblies, the one or more UVC projectors, or the supporting structure with respect to the ground. The optional incorporation of such a control system, may advantageously offer advanced functionalities and a highly optimized and automated operation of the system, especially in the optional cases that the platform is a tractor, or a vehicle or an autonomous or remotely operated vehicle or rover.

[0039] In a preferred embodiment which is according to the previous one and the system also comprises the aforementioned air blowers, the control system is configured to control a power of the air blowers. Also, in a preferred embodiment which is according to any of the previous two ones, the control system comprises computing means, preferably configured to run Al algorithms, more preferably configured to detect and classify plants in real time. These optional configurations of the system may further offer and optimize advanced functionalities of the system.

[0040] In a preferred embodiment, the system further comprises height sensors and / or means for the sensing of ground clearance. In the latter case, the detection of ground clearance of the system or platform above the ground, or the sensing or measurement of the height of the system or of parts of the system, e.g. of the reflector assemblies, with respect to the ground, may be utilized for optionally adjusting said height and for ensuring an optimum operation of the system.

[0041] In a preferred embodiment, the system further comprises actuators configured to move the reflector assemblies, preferably in an up-and-down direction with respect to the ground. In the latter case, the actuators may be advantageously be used for adjusting the height and ground clearance of the system.

[0042] In a preferred embodiment, the system of the first aspect of the invention is a UVC fungicide or germicide system for horticulture.

[0043] The present invention in a second aspect concerns the use of the system of the first aspect of the invention, for protecting horticultural crops or plants from fungi or germs.

[0044] The present invention in a third aspect concerns a method for treating with UVC radiation plants on a ground, the method comprising: using a system which is according to any of the preceding claims; moving the system over the ground and the plants in a first direction; via the one or more UVC projectors (3), generating UVC radiation and collimating and projecting it downwards towards the plants and the ground; via the two or more reflector assemblies which are mounted on the platform and arranged below the one or more UVC projectors and between the mounting frame and the ground, reflecting the non-collimated radiation that is emitted by the one or more UVC projectors towards a second direction (A) which is perpendicular to the first direction (F).

[0045] Hence, in some preferred embodiment of the present invention we use UVC discharge tubes together with linear collimating optics, producing relatively collimated light, illuminating the plants from the top. These UVC projectors are preferably combined with bottom and side reflectors mounted under the projectors and at the sides of each crop row. UVC radiation reflected on the bottom reflectors can reach the reverse surface of leaves, while lateral reflectors may constrain lateral UVC emissions and reflect them towards crop sides.

[0046] To enhance the application of UVC light, the system preferably mounts directional air blowers inducing the stirring of crop leaves, helping the penetration of light into different parts of the plants.

[0047] As the vehicle advances, the blowers may produce stirring waves on the crop canopy, facilitating the penetration of collimated UVC radiation directly coming from the UVC projectors above the crop, and from the reflections coming from lateral and bottom reflectors.

[0048] The UVC projectors are preferably mounted across crop rows and not along them. This is especially preferable in the optional and preferable case wherein the UVC projectors comprise linear collimating optics and discharge tubes (i.e. tubular lamps), and the light is collimated and restricted to a prescribed angle of emission in the direction perpendicular to the discharge tube, while it is generating a much wider illumination distribution in the direction along the tube. By using this arrangement, the UVC projectors light is collimated downwards and has a defined and restricted illumination angle expanding frontwards and backwards in predictable definite angles, while it is restricted by the lateral mirrors in its traverse projection. This advantageously creates a sort of optical fence under the UVC projector area, avoiding the leakage of UVC light in front and behind the application vehicle. The UVC fungicide apparatus described herein may preferably be mounted on or be (e.g. have the form of) an autonomous rover or on a cart being towed by a tractor.

[0049] Good results may be obtained by mounting the UVC fungicide apparatus on an autonomous rove. One reason is because the nocturnal application of UVC treatment of the plants can be particularly facilitated by an autonomous vehicle which can automatically operate by night, avoiding a tractor driver. Another reason is because from an environmental and energy efficiency point of view the UVC treatment operation may be optimised in the optional case that the apparatus is mounted on a lightweight electrical vehicle which can be recharged with photovoltaic panels during the day, yielding a chemical free, zero carbon fungicide protection solution.

[0050] Below, a preferred embodiment of the invention is described.

[0051] The aforementioned UVC collimating projectors preferably comprise and are built around a UVC discharge tube, typically a low-pressure Hg tube emitting with a strong emission peak at 254 nm.

[0052] UVC radiation emitted by the discharge tube is preferably shaped into a relatively collimated beam by using linear collimating optics, like a parabolic through reflector, a CPC (compound parabolic concentrator) reflector or a combination of a linear ellipsoidal reflector with a linear convergent lens.

[0053] To minimize stray rays that may leave the application space, parabolic reflectors are optionally and preferably combined with absorption louvers situated in front of the projectors, with black (UVC absorbing) louver blades parallel to the direction of the collimated beams coming from the reflector and being of such length and distanced between them that stray rays can be circumscribed within a prescribed maximum angle.

[0054] An alternative and optically advantageous configuration is obtained with the combination of a linear ellipsoidal reflector and a linear convergent lens. In this case stray rays can be blocked by a linear diaphragm situated at the second focal point of the ellipsoidal reflector.

[0055] Another option is to use a CPC reflector designed for a specific acceptance angle. In the latter case the CPC reflector can reflect all light coming out from the UVC lamp and circumscribe its emission to the acceptance angle of the CPC. When the two-dimensional CPC is a perfect concentrator, the acceptance angle can be correlated to the concentration ratio with the following formula:

[0056] C = 1 / sin ( 0 )

[0057] Where C is the concentration ratio and 0 (theta) the acceptance half angle of the system. In this case the concentration ratio is defined as the ratio between the tube lamp perimeter and the entry aperture of the concentrator.

[0058] C = A / ( TT * D )

[0059] Where D is the tube diameter and A the entry aperture.

[0060] In this preferred optional case, we are using a CPC reflector not as a concentrator but as a collimator, and the entry aperture of the CPC actually becomes the exit aperture of the collimating optical system.

[0061] Using a CPC reflector design can offer that UVC projectors are emitting the UVC radiation circumscribed within a maximum angle theta in the direction perpendicular to the tube.

[0062] Preferably several of these UVC projectors are mounted perpendicularly to the vehicle’s movement direction, above the crop, with the UVC radiation directed downwards, in such a way that the discharge tubes are perpendicular to the advance direction and parallel to the tunnel openings in the front and in the back of the vehicle. However, it is noted that in a very preferred embodiment of the invention, the system comprises a single UVC projector instead of a plurality of UVC projectors.

[0063] Bottom angled reflectors are preferably mounted on struts hanging from below the main support of the UVC projectors, between crop rows, close to the ground, inclined in such a way that collimated radiation coming from UVC projectors is projected upwards and at an angle towards the bottom side of the leaves.

[0064] Also, parallel lateral reflectors are preferably mounted below the UVC projectors and above the bottom angled reflectors, parallel to the advance direction, in such a way that crop rows are centred in the space between the reflectors. These parallel reflectors reflect the non-collimated radiation emitted by UVC projectors along the UVC lamp tube direction, avoiding the UVC radiation to leave the area below the vehicle, and redirecting it towards the crop canopy.

[0065] Parallel lateral reflectors and bottom angled reflectors are preferably mounted on common supports, constituting side reflector assemblies.

[0066] There are two preferable types of side reflector assemblies: double and single.

[0067] Double side reflector assemblies are preferably situated between contiguous crop rows. They have side and bottom reflectors at both sides, thus reflecting the radiation of the corresponding crop row on each side.

[0068] Single side reflector assemblies are preferably positioned at each end of the extreme rows of the bed. There are two preferable types of single side reflector assemblies, one for the leftmost row of the bed with its reflectors looking to the right and another for the rightmost row of the bed, with its reflectors looking to the left.

[0069] Side reflector assemblies can be fixed at a specified height from the ground, but preferably they are relatively close to the ground, so that the bottom reflectors can pass below the bottom leaves of the crop. This simple approach may work on very flat farms with standardised bed structures.

[0070] For farms with different types of bed structures or more irregular surfaces, mirror assemblies are preferably be able to be mounted in several height positions.

[0071] To improve application flexibility, linear actuators or other kind of mechanical actuators controlled by the system are preferably able to dynamically move the mirror assemblies up and down to keep a desired ground clearance. This may preferably be combined with active sensing of ground clearance and control of actuators stroke.

[0072] Another option is to mount the lower part of the mirror assemblies on a substructure on wheels and have a parallelogram suspension system passively enabling up and down movement of mirror assemblies. In any case, it is preferable to be able to keep the bottom mirrors as close to the ground as possible.

[0073] Additionally, air blowers are preferably mounted in front of the UVC projectors, directing a powerful turbulent airflow on the crop canopy, coming diagonally from the top. This may advantageously induce a stirring movement of the leaves, creating openings in the canopy that may allow collimated UVC light to reach further within the structure of the plants.

[0074] In a simple preferred embodiments, these blowers are mounted in fixed positions, while in its most sophisticate version, blowers are mounted on robotic actuators with one, two or even three degrees of freedom.

[0075] Cameras which are preferably mounted on the front of the vehicle, and combined with on-board computing power (e.g. a computer or other computing means) running Al algorithms, detect and classify plants in real-time.

[0076] By preferably using stereo vision or a combination of vision and LIDAR, a perception system (e.g. the combination of the aforementioned camera system and computing means that is preferably included in the system) further preferably also measures the volume, height and leave surface of crop plants and measures ground clearance.

[0077] This real time crop data (species, variety, height, volume) and the estimated ground distance that may be collected may be used by a control system that is also preferably included in vehicle / apparatus, to manipulate the position, orientation and airflow speed of each blower.

[0078] This may advantageously enable the possibility of creating specific leave stirring patterns that will help penetrate the UVC radiation within the plants structure and reach as much as the surface of the plants as possible.

[0079] The ground distance information can also be used to actively control the height of the mirror assemblies, as explained before. It may be understood that any optional or preferable features mentioned herein with respect to the first aspect of the invention, may correspond to respective optional or preferable features of any of the other aspects of the invention, and vice versa.

[0080] Additional advantages and features of the invention will become apparent from the detailed description that follows and will be particularly pointed out in the appended claims.

[0081] BRIEF DESCRIPTION OF THE DRAWINGS

[0082] To complete the description and in order to provide for a better understanding of the invention, a set of drawings is provided. Said drawings form an integral part of the description and illustrate embodiments of the invention, which should not be interpreted as restricting the scope of the invention, but just as examples of how the invention can be carried out. The drawings comprise the following figures:

[0083] Fig. 1 illustrates a view of a preferred embodiment of a system of the first aspect of the invention.

[0084] Fig. 2 illustrates a lateral view of the embodiment of Fig. 1.

[0085] Fig. 3 illustrates a frontal view of the embodiment of Fig. 1 .

[0086] Fig. 4 illustrates a view of another preferred embodiment of a system of the first aspect of the invention.

[0087] Fig. 5 illustrates part of the embodiment of Fig. 4.

[0088] Fig. 6 illustrates is another view of the embodiment of Fig. 4.

[0089] Fig. 7 illustrates is a bottom view of the embodiment of Fig. 4.

[0090] Fig,.8 illustrates a view of wireframe axonometric view of a UVC projector of a preferred embodiment of a system of the first aspect of the invention.

[0091] Fig. 9 illustrates a cross section of the UVC projector 3 of Fig. 8, and also illustrates a working principle related to the operation of a preferred embodiment that includes the UVC projector 3.

[0092] Fig. 10 illustrates a frontal view of a preferred embodiment of a system of the first aspect of the invention and also illustrates a safety working principle related to the operation of this preferred embodiment.

[0093] Fig. 11 illustrates a schematic diagram of a control architecture of a preferred embodiment of a system of the first aspect of the invention. Fig. 12 to 15 illustrate respective alternative systems for the automatic ground clearance adjustment of side reflector assemblies of respective preferred embodiments of the first aspect of the invention.

[0094] Fig. 16 illustrates an extended control system of a preferred embodiment of a system of the first aspect of the invention.

[0095] DESCRIPTION OF A WAY OF CARRYING OUT THE INVENTION

[0096] The following description is not to be taken in a limiting sense but is given solely for the purpose of describing the broad principles of the invention. Next embodiments of the invention will be described by way of example, with reference to the above-mentioned drawings.

[0097] Figure 1 (i.e. Fig. 1) is a general axonometric top view of a preferred embodiment of a UVC apparatus 1 .

[0098] Arrow F depicts the forward movement direction while arrow A depicts the direction parallel to the ground and perpendicular to (across) forward direction F. It may be understood that direction F is the aforementioned first direction, and direction A is the aforementioned second direction. It is also noted that as is explained further below the embodiment of Fig. 1 , comprises air blowers 13, bottom angled reflectors, and a plurality of UVC projectors 3, however it is noted that another preferred embodiment of the invention comprises only one UVC projector and does not comprise bottom reflectors nor any air blowers.

[0099] Figures 2 and 3 are frontal and lateral views respectively of the UVC apparatus 1 of Fig. 1.

[0100] UVC apparatus 1 is mainly composed of an UVC array 2 of UVC projectors 3 mounted on a mounting frame 6.

[0101] UVC apparatus 1 is mounted on a vehicle 15 that herein is also called “porting vehicle”. Porting vehicle 15 can be an autonomous rover 16, a tractor trailer 17 or any alternative suitable moving platform.

[0102] In the figures 4 to 7 an autonomous rover 16 is shown.

[0103] In the embodiment of Fig. 4 to Fig. 7 UVC projectors 3 are mounted across the forward movement direction F of the porting vehicle.

[0104] UVC projectors 3 project UVC radiation downwards, perpendicularly to the ground.

[0105] Several mirror assemblies 7 (i.e. reflector assemblies) are mounted under mounting frame 6.

[0106] Mirror assemblies 7 are composed of parallel lateral reflectors 8 and bottom angled reflectors 9.

[0107] There are three different types of mirror assemblies 7 depending on their position respect crop rows: double side reflector assemblies 10, left single reflector assembly 11 and right single reflector assembly 12.

[0108] Double side reflector assemblies 10 are situated between adjacent crop rows. They have parallel lateral reflectors 8 and bottom angled reflectors 9 on both sides.

[0109] A left single reflector assembly 11 is situated between the leftmost crop row and porting vehicle 15 lefthand wheels or tracks. This has a parallel lateral reflector 8 and bottom angled reflector 9 on its righthand side.

[0110] A right single reflector assembly 12 is situated between the rightmost crop row and porting vehicle 15 righthand wheels or tracks. This has a parallel lateral reflector 8 and bottom angled reflector 9 on its lefthand side.

[0111] Figure 4 is a general axonometric top view of UVC apparatus 1 mounted on autonomous rover 16, also showing some crop plants 20 being treated. Arrow F indicates the forward movement direction.

[0112] Figure 5 is like the previous view but without protecting cover 19. Crop plants 20 are planted in rows. The inter-row distance being so that crop plants 20 lie between reflector assemblies 7, avoiding physical interference during operation.

[0113] UVC apparatus 1 includes one left single reflector assembly 11 and one right single reflector assembly 12. The number of double side reflector assemblies 10 are preferably equal to the number of crop rows minus one. Therefore, it is possible that no double side reflector assemblies 10 are mounted when crop plants are aligned in a single row.

[0114] UVC apparatus 1 is configured and mounted in such a way that UVC projectors 3 and reflector assemblies 7 cannot physically interfere with standing crop plants 20 during the forward movement of the mounting vehicle. UVC projectors 3 are mounted at enough height to allow crop plants 20 to pass beneath them without physical interference.

[0115] Figure 6 is a general axonometric bottom view of UVC apparatus 1 mounted on an autonomous rover 16.

[0116] Figure 7 is a bottom view of UVC apparatus 1 mounted on an autonomous rover 16.

[0117] UVC apparatus 1 also includes air blowers 13, mounted on mounting frame 6 above and between side reflector assemblies 7, so that there is an air blower 13 above each row of crop plants 20.

[0118] Air blowers 13 are mounted with their axial flow pointing downwards in a rather inclined attitude, not perpendicular to the ground. Their mission is to create a powerful airflow directed to the crop plants canopy.

[0119] UVC apparatus 1 optionally includes at least one camera system 14. Camera system 14 may have several cameras, like a stereo camera arrangement, and may include other sensors, like a LIDAR.

[0120] The objective of camera system 14 is to gather crop data that can be used to fine-tune UVC treatment parameters, like UVC lamp 4 power, porting vehicle 15 speed and air blowers 13 airflow.

[0121] Figure 8 is a wireframe axonometric view of a UVC projector 3. UVC projector 3 is composed of UVC lamp 4 and collimating reflector 5.

[0122] Collimating reflector 5 is shaped as a linear compound parabolic concentrator (CPC), working as an optical collimator.

[0123] This arrangement is designed to assure a defined maximum divergence angle theta from any rays emitted by UVC lamp 4 or reflected by collimating reflector 5. Rays emitted by UVC projector 3 are restricted in its F direction.

[0124] Figure 9 shows a cross section of UVC projector 3 cut across tubular UVC lamp 4, and it shows the safety working principle of UVC apparatus 1 along forward direction F.

[0125] UVC lamp 4 has a tubular shape and is oriented along arrow A.

[0126] The across the tube component, along arrow F, of UVC radiation emitted by UVC lamp 4 is constrained within half angle theta by collimating reflector 5.

[0127] UVC projectors 3 are mounted at height h above the ground (22).

[0128] As incident UVC radiation emitted by UVC lamp 4 is constrained within half angle theta, any accidental specular ground reflection (23) will therefore also be contained within half angle theta, in such a way that a protective cover 19 of length 2*tan(theta)*h mounted at height h will block any specular UVC ground reflection, avoiding harmful UVC radiation to leak away from the intended treatment area.

[0129] Figure 10 shows a frontal view of UVC apparatus 1 and depicts its safety working principle across the forward direction F.

[0130] Some rays emitted by UVC projectors 3 directly impinge on the top of crop plants (25).

[0131] Stray rays emitted by UVC projectors 3 perpendicular to forward direction F are reflected by reflector assemblies 7. Some rays are reflected once on parallel lateral reflectors 8 and tend to impinge on the side of crop plants (26).

[0132] Other rays are reflected once on bottom angled reflectors 9 (26) or are reflected two times, first on lateral reflectors 8 and then on bottom angled reflectors 9 (27). These rays tend to impinge on the bottom of crop plants 20.

[0133] Thanks to the combined position of UVC projectors 3 and mirror assemblies 7 the UVC radiation is evenly distributed on the crop canopy and at the same time is constrained within the application space, collimating reflectors 5 constraining the UVC radiation in the forward F direction and mirror assemblies 7 constraining the UVC radiation in the across A direction.

[0134] Air blowers 13 create a forced airflow 30 which impinges on crop plants 20, stirring their leaves, creating openings which favour the penetration of the UVC radiation within the canopy of crop plants 20.

[0135] Figure 11 depicts a schematic diagram of the UVC apparatus 1 control architecture.

[0136] UVC projectors 3 are powered by an electric power system managed by control system 29, allowing for a degree of control on the power of UVC lamps 4.

[0137] Camera system 14 is to be used in conjunction with control system 29. Control system 29 may include neural network Al algorithms that would identify the species of crop plants 20 being treated.

[0138] Also, by using a stereo vision arrangement or alternatively using a synchronised LIDAR, control system 29 can obtain volume and height information of crop plants 20. With this information, control system 29 can adjust the power of UVC lamps 4, the airflow of air blowers 13 and / or the speed of porting vehicle 15.

[0139] Thanks to control system 29 the right dose of UVC radiation can be applied by adjusting the vehicle speed, the airflow rate on the crop and the UVC irradiance level. Also, by reading a ground clearance distance from height sensor 35 mounted on mounting frame 6, control system 29 can control the height of side reflector assemblies 7, using any of the active control methods described in the following paragraphs.

[0140] Figures 12 to 15 depict alternative systems for the automatic ground clearance adjustment of side reflector assemblies 7. Each of these alternative systems may also be understood as being a respective type of heigh adjusting means.

[0141] On very flat lands a fixed mounting height for side reflector assemblies 7 can be acceptable, but on more rough lands or on farms having different bed configurations, an automated height adjustment is preferably required.

[0142] Figure 12 depicts an arrangement having actuated revolute joints 31 actuating on bars 32 pivoting on revolute joints 33 attached to mounting frame 6 in one end, and to side reflector assemblies 7 in the other end, allowing for the differential adjustment on the front and the rear ground clearance of side reflector assemblies 7 above ground 22.

[0143] Figure 13 depicts an alternative arrangement having actuated prismatic joints 34 linking mounting frame 6 and side reflector assemblies 7, also allowing for the differential adjustment on its front and rear ground clearance.

[0144] Figure 14 depicts an arrangement having a single actuated revolute joint 31 , attached to mounting frame 6 and actuating on bar 32, attached in its other end to side reflector assembly 7 through unactuated revolute joint 33, while a second bar 32 links mounting frame 6 and side reflector assembly 7 through unactuated revolute joints 33, the ensemble constituting a four-bar link or parallelogram. This is a simpler arrangement with a single motor per side reflector assembly 7 but may not allow for differential height adjustments between front and rear.

[0145] In all these three arrangements the ground clearance is preferably actively controlled by control system 29 using data coming from some sort of height sensor 35, for instance a laser rangefinder, mounted on mounting frame 6 and looking towards ground 22, or alternatively mounted on side reflector assemblies 7. Figure 15 depicts an alternative passive height control system, based on a four-bar link arrangement with unactuated revolute joints 33 linking mounting frame 6 and side reflector assemblies 7 through bars 32, and having a wheel 36 mounted on the lower end of each side reflector assembly 7, supporting its weight on ground 22. In this case the parallelogram arrangement passively moves up and down following the ground irregularities.

[0146] Figure 16 depicts an extended control system 29 using signals from height sensors 35 to actively control side reflective assemblies 7 ground clearance through actuated joints 31 (revolute) or 34 (prismatic).

[0147] As depicted in figure 17, an alternative technique to control the ground clearance of side reflector assemblies 7 consists in mounting UVC apparatus 1 on a porting vehicle 15 which incorporates an active suspension system with ground clearance regulation capacity.

[0148] In this case, side reflector assemblies 7 are mounted below mounting frame 6 at a fixed position.

[0149] In the example shown, parallelogram suspensions for each wheel are mounted on actuated revolute joints 31. Control system 29 may regulate these actuated revolute joints to lift or lower the suspension at each corner of porting vehicle 15, thus lifting or lowering UVC apparatus 1 and its attached side reflector assemblies 7. Other active suspension arrangements using hydraulics or electrical drives can be used.

[0150] In this text, the term “comprises” and its derivations (such as “comprising”, etc.) should not be understood in an excluding sense, that is, these terms should not be interpreted as excluding the possibility that what is described and defined may include further elements, steps, etc.

[0151] The invention is obviously not limited to the specific embodiment(s) described herein, but also encompasses any variations that may be considered by any person skilled in the art within the general scope of the invention as defined in the claims.

Claims

1. 22CLAIMS1. A system for illuminating with UVC radiation plants on the ground, the system comprising:- a platform comprising a mounting frame (6) configured to move in a first direction (F) over plants growing on the ground;- one or more UVC projectors (3) mounted on the mounting frame (6), each UVC projector (3) comprising a tubular UVC lamp (4) extending along a lamp axis (A) substantially perpendicular to the first direction (F), and collimating optics (5) configured to limit divergence of UVC radiation emitted by the tubular UVC lamp (4) in a direction perpendicular to the lamp axis (A), the one or more UVC projectors (3) being arranged to direct UVC radiation downward toward the plants; and- two or more reflector assemblies (7) mounted on the platform at longitudinal ends of the one or more UVC projectors (3) along the lamp axis (A), each reflector assembly (7) comprising at least one lateral reflector (8) oriented substantially perpendicular to the lamp axis (A) and configured to intercept UVC radiation emitted along the lamp axis (A) and to redirect said radiation toward the plants.

2. The system of claim 1 , wherein the plants are arranged in parallel rows, and wherein the reflector assemblies (7) comprise:- a single reflector assembly (11 , 12) positioned at each outer side of the platform; and- one or more double reflector assemblies (10) positioned between adjacent rows of plants, each double reflector assembly (10) comprising a lateral reflector (8) oriented between the rows.

3. The system of claim 1 or 2, wherein each reflector assembly (7) further comprises a bottom reflector (9) inclined to reflect UVC radiation upward toward undersides of plant leaves.

4. The system of any of the preceding claims, wherein the collimating optics (5) are configured to restrict divergence of UVC radiation emitted by the tubular UVC lamp (4) in the direction perpendicular to the lamp axis (A) to a maximum half-angle 0.

5. The system of claim 4, wherein the collimating optics (5) comprise a linear compound parabolic concentrator (CPC).

6. The system of claim 4, wherein the collimating optics (5) comprise louvers arranged to absorb or block UVC radiation emitted outside the maximum half-angle 0.

7. The system of claim 4, further comprising a protective cover (19) positioned to block specular reflections of UVC radiation from the ground, the protective cover (19) having a length at least equal to 2 tan(0) h, where 0 is the maximum half-angle defined in claim 4 and h is the height of the protective cover (19) above the ground.

8. The system of any of the preceding claims, wherein each tubular UVC lamp (4) is a low- pressure mercury discharge lamp.

9. The system of any of the preceding claims, wherein the one or more UVC projectors (3) are mounted at a height sufficient to pass above the plants during operation.

10. The system of any of the preceding claims, further comprising one or more air blowers (13) mounted on the platform and configured to direct air toward the plants at an angle relative to vertical.

11. The system of any of the preceding claims, further comprising at least one imaging or sensing system (14) comprising one or more cameras and / or a LIDAR.

12. The system of any of the preceding claims, further comprising a control system (29) configured to:- control power of the tubular UVC lamp (4);- adjust a moving speed of the platform;- identify species of the plants;- obtain plant height and / or volume data; and- adjust a height of the reflector assemblies (7), the one or more UVC projectors (3), or the mounting frame (6) relative to the ground.

13. The system of claim 10 or 12, wherein the control system (29) is further configured to control power of the one or more air blowers (13).

14. The system of claim 12 or 13, wherein the control system (29) comprises computing means configured to execute artificial intelligence algorithms to detect and classify plants in real time.

15. The system of any of the preceding claims, further comprising one or more height sensors (35) configured to sense ground clearance.

16. The system of any of the preceding claims, further comprising height-adjustment means configured to adjust a height of two or more reflector assemblies (7), and optionally also the one or more UVC projectors (3) or the mounting frame (6), relative to the ground.

17. The system of any of the preceding claims, further comprising actuators configured to move the reflector assemblies (7) up and down relative to the ground.

18. The system of any of the preceding claims, wherein the platform is autonomous or remotely operated.

19. The system of any of the preceding claims, wherein the platform is selected from: a cart, a vehicle (15), a rover, a trailer, a tractor trailer (17), a tractor cart, or an autonomous or remotely operated rover (16) or vehicle.

20. Use of a system according to any of claims 1 to 19 for protecting plants from fungi.

21. A method for treating plants with UVC radiation, the method comprising:- moving a system according to any of claims 1 to 19 in the first direction (F) over plants growing on the ground;- operating the one or more UVC projectors (3) to generate UVC radiation, collimating the UVC radiation in the direction perpendicular to the lamp axis (A), and projecting the UVC radiation downward toward the plants; and- reflecting, by means of the reflector assemblies (7), UVC radiation emitted along the lamp axis (A) toward the plants.

22. The method of claim 21 , further comprising operating the one or more air blowers (13) to stir plant foliage and thereby improve penetration of UVC radiation into the plant canopy.

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