GB2609642A

GB2609642A - Apparatus and method for electrically killing plants

Info

Publication number: GB2609642A
Application number: GB2111564.7A
Authority: GB
Inventors: Lawrence Diprose Andrew; Alistair Holdgate James; Frederick Diprose Robert
Original assignee: Ubiqutek Ltd
Current assignee: Ubiqutek Ltd
Priority date: 2021-08-12
Filing date: 2021-08-12
Publication date: 2023-02-15
Also published as: GB202111564D0; WO2023017272A1

Abstract

An apparatus for electrically killing or attenuating the growth of plants 14, the apparatus including: an electrical energy supply unit 4; a contact determination system 16; an applicator unit 6 comprising an applicator electrode, and a return unit 8 comprising a return electrode. The electrical energy supply unit is arranged to apply electrical energy 10 through a transmission circuit 12 comprising the applicator electrode, and the return electrode. The contact determination system 16 is arranged to determine if an amount of physical contact between the return electrode and the ground has crossed a threshold, and, if said threshold is crossed, to attenuate the electrical energy 10 or prevent transmission of the electrical energy through the transmission circuit 12.

Description

APPARATUS AND METHOD FOR ELECTRICALLY KILLING PLANTS

TECHNICAL FIELD

The present disclosure relates to electric apparatus that is configured to attenuate plant growth by the application of electrical energy thereto.

BACKGROUND

In properties both commercial and domestic, it is common to kill or at least control the growth of unwanted plants, commonly referred to as weeds. Conventional methods include treatment with a pesticide or more particularly a herbicide. However, there is a growing concern over such treatment for environmental reasons and unwanted exposure of herbicides to humans and animals. Moreover, weeds are increasingly becoming naturally resistant so herbicides are becoming more and more ineffective. As a result of these numerous drawbacks, consumers are increasingly demanding organic produce, for which the use of herbicides is increasingly prohibited.

Consequently, there is a desire for alternative treatments, which do not include the above drawbacks. An example includes treatment by the application of electrical energy. US4338743 A discloses such apparatus, wherein an electrical energy is applied at 14.4 kV at 60 ± 5 Hz to plants.

Such apparatus have failed to become widespread in the market over concern over safety. For example, the high voltage may be a risk to a person in proximity to a treated weed, particularly if the electrical energy is not appropriately confined to a circuit comprising the apparatus and the weed.

Therefore, in spite of the effort already invested in the development of said apparatus further improvements are desirable.

SUMMARY

The present disclosure provides electrical apparatus to kill a plant or at least attenuate plant growth including weaken a plant. The apparatus includes an electrical energy supply unit; an applicator unit comprising an applicator electrode; a return unit comprising a return electrode and; electrical circuitry. The electrical energy supply unit is arranged to apply electrical energy through a transmission circuit comprising the applicator electrode and the return electrode and (in use) a plant.

In embodiments, the electrical energy supply unit is arranged to apply electrical energy with a waveform having a repeating unit with frequency through the transmission circuit.

As used herein the term "return electrode" may refer to a single element consisting of said return electrode, or a plurality of electrodes implemented as the return electrode.

In embodiments, a material forming the return electrode has a thickness (t) in m that is defined by the relationship: t > D, wherein D = F-P*C-n1 F is the frequency in Hz, P is the magnetic permeability in Him, which is calculated by multiplying the relative magnetic permeability pr by the permeability constant po in Him, and C is the electrical conductivity in Sim.

With a thickness of electrode defined by said relationship, it may be ensured that the electrode has sufficient thickness for a particular expected frequency of electrical energy. For example, if the electrode is too thin it may be subject to one or more of the following or other undesirable conditions: overheating causing the electrical energy to take an unpredictable path that could be dangerous to a person in proximity of the apparatus; become dangerously hot, and; have an undesirably high electrical resistance. In particular, as the frequency of the electrical energy is changed the return electrode may also be changed to maintain compliance with said inequality.

A maximum thickness of the return electrode may be 100.t or 500.t. A maximum thickness may be selected so that the return electrode remains easily insertable into the ground. A maximum thickness maybe selected to avoid material wastage, that is, due to a surface effect (of high frequency electrical energy primarily traveling though a surface, rather than a centre) increasing thickness may have little difference in avoiding overheating.

In embodiments, the return electrode is arranged with said thickness over at least 70% or 80% or 90% or over the entire of the return electrode. With such a range any areas of thickness less than those specified by said relationship may be minimised, such that local hotspots of high temperature and electrical resistance can be avoided.

In embodiments, for any given spherical volume with a radii of 1 cm or 2 cm or 5 cm, the return electrode is arranged with said thickness t to be an average of greater than D. In embodiments, the return electrode has a surface areas in cm2 of greater than 10,000 F is the frequency in Hz, p is the density in kg/cm8, R is the electrical resistivity in am, S is the specific heat capacity in J.Kg-1.K-1. With such a range of surface area, it may be ensured that the electrode has sufficient surface area to prevent overheating of the exterior surface, which is undesirable for any of the aforementioned reasons. In particular, as the frequency is increased the electrical current has been found to be transmitted primarily through the surface of the electrode, due to a surface effect, hence it is desirable to maximise the surface area as specified by the above-relationship.

In embodiments, the return electrode has a specific heat capacity of 200 -1000 J.Kg1K-1, or 300 -600 J.Kg-1.K-1 It has been found that with such a specific heat capacity range, particularly in combination with the thickness range defined by the above relationship, the electrode may be less likely to overheat and therefore be subject to one of the aforementioned problems.

In embodiments, the return electrode has an electrical resistivity of less than 1 x 10-6 to 1 x 10-8 am or 8 x 10-7 to 1 x 10-8 am. It has been found that with such an electrical resistance range, particularly in combination with the thickness range defined by the above relationship, the electrode may be less likely to overheat and therefore be subject to one of the aforementioned problems.

In embodiments, the apparatus is arranged to apply a power of SOW to 20 kW through the return electrode. It has been found that with such an electrical power range, particularly in combination with the thickness range defined by the above relationship, the electrode may be less likely to overheat and therefore be subject to one of the aforementioned problems.

In embodiments, the apparatus is arranged to include a handheld, portable unit comprising at least the applicator unit. The handheld portable unit may include the electrical energy supply unit. It has been found that combining an earth electrode according to any of the preceding embodiments with such a handheld, portable unit may provide a convenient to use apparatus that a user can implement manually, e.g. including manual insertion of the earth electrode into the ground.

In embodiments, the return electrode is arranged for insertion into the ground. As used herein the term "arranged for insertion into the ground" may refer to the earth electrode with an elongate dimension (e.g. a plate or a spike), that has a structural strength sufficient to enable its insertion into a typical portion of ground (e.g. soil, sand or clay) without deforming so that an electrical connection between the ground and return electrode can be made. In may include that the shape is selected so that it can be manually inserted into the ground by a user, e.g. when subject to an insertion force of less than 2000 N or 1000 N. In embodiments, the return electrode is arranged as a plate. As used therein the term "plate" may refer to a geometric arrangement with a substantial longitudinal and lateral axis compared to a depth axis. A plate may include: a member with principal faces which are parallel and opposed in the longitudinal and lateral axis; a wedge with principle faces separated by an acute angle, e.g. at 5 to 45 degrees, and; combinations thereof or other similar shaped object.

By implementing the return electrode to have the substantial form of a plate one of more or other advantages may be provided: the return electrode may be conveniently manufactured, e.g. from sheet material; the return electrode may be convenient to insert into the ground; the return electrode may implement a large surface area which may be advantageous for reasons previously discussed.

In embodiments, the plate includes an angled periphery for insertion into the ground. By implementing a tip/edge of the plate to be angled for insertion into the ground, the plate may be easier for a user to push into the ground. As used therein the term "angled periphery for insertion into the ground" may refer to any shaping of the edge of the plate to facilitate more convenient insertion than a flat face and may include one or more of; a sharpening protrusion; an angled edge; a curved edge, and; other formation.

In embodiments, the return electrode extends in a longitudinal direction from a tip to a top surface, and the angled periphery is arranged to cover the portion of the periphery of the plate that faces the ground in an insertion direction (e.g. a portion of the plate that is seen when looking at the plate in the longitudinal direction).

For embodiments implementing the thickness t defined by the aforedescribed relationship t> D, the thickness may apply distal said angled periphery.

In embodiments, the pate has a thickness t to longitudinal length I (where I is a tip to end surface dimension) ratio of 0.02 -0.2. With such a range a suitable large surface area relative to the mass may be provided.

In embodiments, the return electrode extends in a longitudinal direction from a tip to a top surface, and a region of maximum lateral dimension is arranged distal the tip. By implementing the return electrode to have a maximum lateral dimension away from the tip, in combination with the plate shape, the return electrode may be easier to insert into the ground, since the lateral dimension can increase progressively from the tip. Such an arrangement may also provide good electrical contact with the ground.

In embodiments, an angled periphery extends over the region of maximum lateral dimension. In embodiments the angled periphery extends from the tip to the section of maximum longitudinal dimension. By implementing the sharp periphery to extend along the sides up to (including beyond) the section of maximum width, the return electrode may be 1) easier to insert into the ground and 2) easier to extract from the ground, since a user can move the inserted electrode in the lateral direction (which is facilitated by the sharp edges to cut through the ground) to introduce play between the return electrode and ground as part of an extraction process.

In embodiments, the return electrode tapers with decreasing lateral dimension (i.e. width) and/or thickness from the section from maximum lateral dimension to a top surface and/or the tip. By implementing a wedge shape at the top of the return electrode, contact with the ground at said top of the electrode may be reduced which may encourage the electrical energy to travel deeper into the ground and therefore the roots of a treated pant.

In embodiments, the return electrode extends in a longitudinal direction from a tip to a top surface and a thickness tapers with increasing thickness from the tip to the top surface and/or a portion of maximum lateral dimension. With a wedge shape the electrode may be more convenient to insert into the ground and may provide a better conductive connection to the ground since the wedge progressively increases the lateral compression of the ground with increasing insertion depth.

In embodiments, the return electrode extends in a longitudinal direction from a tip to a top surface and the top surface is planar and arranged to apply an axial force in the longitudinal direction from an impactor aligned to the longitudinal axis. With a planar top surface the return electrode may be hit with an impactor (e.g. a hammer) or pushed with a user's foot to aid insertion into the ground.

In embodiments, the return electrode includes an engagement member for engagement with a driver to extract the return electrode from the ground. By implementing an engagement member a user may more conveniently extract the return electrode from the ground. In embodiments, the engagement member is arranged as a slot or ridge that may extend with a major axis in the lateral direction on a side surface of the return electrode. By implementing the engagement member as a slot or a ridge a tool (e.g. a spade) may be engaged therewith and used to lever the return electrode out of the ground In embodiments, the engagement member is arranged in a top surface to mechanically couple with the driver. By arranging the engagement member to be accessible via top surface a user may engage a tool, e.g. by a screw-fit to conveniently extract the return electrode from the ground.

In embodiments, the return unit comprises a temperature control system to determine if a temperature of the return electrode has crossed a threshold. In embodiments, if said threshold is crossed the temperature control system may: control the transmission of the electrical energy through the transmission circuit, for example, the electrical energy may be attenuated or prevented, and/or; provide a notification via a user interface to a user that the return unit is too hot, which may include an instruction to replace and/or move the location of the return electrode.

With such an arrangement, a user may be prevented from using the apparatus or be notified if the return electrode is too hot, which for the above-mentioned reasons, may improve safety.

In embodiments, the temperature control system includes a sensor system. In embodiments, the sensor system provides information (e.g. digital information or a signal) based on a temperature of the return electrode. The sensor system may be implemented as one or more of: a thermocouple; a thermopile; an infrared camera system, and; other suitable sensor.

In embodiments, the sensor system provides said information to electrical circuitry, which determines if a temperature threshold is crossed based on said information. In embodiments, the electrical circuitry implements said control of the user interface and/or the electrical energy (e.g. by control of an electrically operated switch in the transmission circuit or by control of the power supply). It will be understood that the components of the temperature control system may be located partially (e.g. where appropriate distributed on other components of the apparatus) or fully on the return unit.

In embodiments, the sensing system is conductively coupled to the return electrode. In embodiments, said coupling is via a direct connection to the return electrode. In embodiments, said coupling is via a conductive extension, which may extend from a top surface of the return electrode, such that the or each temperature sensor is not arranged in the ground when the return electrode is inserted in the ground. It may be advantageous not to have the temperature sensors arranged in the ground since they may be susceptible to damage when subject to subterranean conditions.

In embodiments the sensing system is electrically isolated from the transmission circuit. By isolating the temperature sensor from the transmission circuit, circuitry of the temperature sensor may be avoided as a return path for the high energy, which may otherwise cause damage to the temperature control system.

In embodiments, the return electrode is arranged as a plurality of teeth operafivity arranged for insertion into the ground. By implementing the return electrode as a plurality of teeth, or otherwise shaped extensions, which are electrically connected, an improved electrical connection to the ground may be achieved.

In embodiments, the return unit comprises: a body comprising to receive an electrical connection to the transmission circuit, the return electrode and body couplable in a coupled configuration and separable in a decoupled configuration, wherein in the coupled configuration, the body electrically connecting the return electrode to the transmission circuit. In the decoupled configuration the return electrode is not electrically coupled to the transmission circuit.

By implementing a two-part system with a separable return electrode, which is electrically couplable to the transmission circuit via a connection to a body, the return electrode can, in a separate step be inserted into the ground, which may otherwise cause damage to a body if it were connected, and enable the return electrode to be properly and precisely inserted into the ground, and then be connected to the transmission circuit. Moreover, convenient replacement of depleted return electrodes may be facilitated.

In embodiments, the return electrode and body are arranged with the return electrode to be insertable into the ground in the decoupled configuration, and to be maintained inserted in the ground as the return unit is transitioned to the coupled configuration. By allowing the return electrode to remain in the same position, i.e. inserted in the ground, as the return unit is transitioned from the decoupled to the coupled configuration, it may be ensured that a precise electrical connection of the return electrode to the ground, which is facilitated by a separable system, is maintained once coupled to the body.

In embodiments, return electrode and body are arranged with the return electrode to be inserted in the ground as the return unit is transitioned from the coupled configuration to the decoupled configuration. With such an implementation the body may be conveniently decoupled from the electrode before a step of extracting the return electrode from the ground, which may otherwise cause damage to a coupled body.

In embodiments, the body is arranged in the coupled configuration to prevent a user from touching a portion of the return electrode that is exposed with respect to the ground. By arranging a coupled body to prevent a user from touching a return electrode which is inserted into the ground, the apparatus may be safe.

In embodiments, the return unit comprises a coupling detection system which is arranged to determine if the return electrode and body are in the coupled configuration or the decoupled configuration. In embodiments, the coupling system can: control the transmission of the electrical energy through the transmission circuit, for example, the electrical energy may be attenuated or prevented, and/or; provide a notification via a user interface to a user that the return unit is in the decoupled configuration, which may include an instruction to replace and/or couple the return electrode.

By implementing a coupling detection system a user may be less likely to operate the apparatus when the return electrode is incorrectly arranged, which may improve safety.

In embodiments, the coupling detection system includes a detection unit. In embodiments, the detection unit includes a sensor system to provide information (e.g. digital information or a signal) based on the coupling configuration. The sensor system may be implemented as one or more of: a mechanical sensor (e.g. a switch that is triggered by an actuator); a camera system; an optical sensor; a sensor arranged to detect an open circuit caused by the return electrode being separate from the return unit, and; other suitable sensor.

In embodiments, the sensor system provides said information to electrical circuitry, which determines the coupling configuration based on said information. In embodiments, the electrical circuitry implements said control of the user interface and/or the electrical energy (e.g. by control of an electrically operated switch in the transmission circuit or by control of the power supply). It will be understood that the components of the coupling detection system may be located partially (e.g. where appropriate distributed on other components of the apparatus) or fully on the return unit.

In embodiments, the return unit comprises a coupling system to mechanically couple return electrode and body. In embodiments, the coupling system comprises a removable coupling. As used herein the term "removably coupling" may refer to any coupling system designed for quick connection and disconnection, it may include one or more of a: interference fit; a threaded connection; a bayonet connection; other suitable connection, and; a connection arrangement that does not require a tool to operate.

In embodiments, a coupling system implements electrical coupling of the return electrode to the transmission circuit via the body. By implementing a coupling system that both mechanically secures the return electrode to the body and electrically couples it to the transmission circuit (e.g. electrical energy also transmits though the mechanical coupling), a return unit of reduced complexity may be implemented.

In embodiments, the return unit of any preceding claim, wherein the coupling system is arranged as an engagement member of body to engage with a complimentary engagement member of the return electrode, wherein the engagement members electrically couple the return electrode to the transmission circuit. In embodiments, the engagement members are arranged to be at least partially below ground in the coupled configuration. With such an arrangement, the engagement member of the return electrode may not protrude above ground, which could otherwise interfere with a driver when driving the return electrode into the ground.

In embodiments, the engagement member of the return electrode is arranged as a cavity to receive the engagement member of the body, which is arranged as a complimentary extension. The cavity may include an aperture for release of debris.

In embodiments, a housing of the body is arranged to extend around the return electrode in the coupled configuration, such that the return electrode is not exposed when is inserted in the ground is covered. With such an arrangement a user may be prevented from touching the return electrode.

In embodiments, the return unit includes a cooling system arranged to cool the return electrode in the coupled configuration. A cooling system may cool the return electrode to reduce overheating, which may increase an envelope of operation of the apparatus. In embodiments, the cooling system comprises one or more of: a conductive heat transfer-based system, and; a convective heat transfer based system.

In embodiments, the conductive heat transfer system comprises a terminal (e.g. a thermally conductive member) of the body which, with the return unit in the coupled configuration, electrically couples the return electrode to the transmission circuit and/or mechanically couples the return electrode to the body. By implementing a conductive heat transfer system that also electrically connects the return electrode to the transmission circuit and/or provides the mechanical coupling, coupling of the body and return electrode may be simplified. The terminal may be of greater volume than an electrical wire so as to transfer a significant amount of heat, e.g. with a cross sectional area of greater than 5 or 10 or 20 mm2. The terminal may be a solid piece of material as opposed to a wire.

In embodiments, the convective heat transfer system comprises one or more apertures arranged in a housing of the body to enable convective cooling of the return electrode, including directly and/or via the terminal.

In embodiments, the body comprises a ground engaging portion, that presents a planar surface to abut the ground. The planar surface may prevent insertion into the ground when subject to a manual force applied by the user, e.g. when subject to an insertion force of less than 2000 N or 1000 or 500 N. By preventing the body from being insertable into the ground, it may be ensured that it does not insert into the ground when transitions to the coupled configuration, which may otherwise cause incorrect coupling etc. In embodiments, the apparatus includes a contact determination system which is arranged to determine an amount of physical contact between the return electrode and the ground. In embodiments, the contact determination system is arranged to determine if said amount of physical contact has crossed a threshold. In embodiments, if said threshold is determined as crossed the contact determination system may: control the transmission of the electrical energy through the transmission circuit, for example, the electrical energy may be attenuated or prevented, and/or; provide a notification via a user interface to a user that there is insufficient physical contact, which may include an instruction to replace and/or move the location of the return electrode.

With such an arrangement, a user may be prevented from using the apparatus or notified if the there is insufficient physical contact between the return electrode and the ground, which for the above-mentioned reasons, may improve safety.

By determining if the return electrode is in sufficient physical contact with the ground, it may be assumed that there is sufficient an electrical connection between the return electrode and the ground for safe transmission of the electrical energy through the transmission circuit. Although a determination of touching the ground does not necessarily equate to a sufficiently electrically conductive connection, it may be a more cost-effective alternative (or of value in addition) to determining whether there is an adequate electrically conductive connection, which can be implemented by alternative means, such as attenuation of a test signal etc. As used herein the term "physical contact between the return electrode and the ground" may refer to one or more of the following conditions: condition 1 -a level of insertion of the return electrode into the ground; condition 2 -a pull-out force required to extract the electrode from the ground, e.g. if the pull out force is below a threshold, then insufficient physical contact may be determined (as an example the electrode may be determined as fully inserted as for condition 1 but it may be sitting too loosely in a cavity defined by the ground); condition 3 a position on the surface of the return electrode being in direct contact with the ground, and; other suitable condition.

For the aforementioned conditions the threshold may be defined as: condition 1 -a position on the return electrode exceeding a position of the ground, e.g. a top surface of the return electrode exceeding ground level; condition 2 -the return electrode pulling out from the ground when subject in a longitudinal direction to a predetermined insertion force; condition 3 -one or both of the principal faces of the return electrode not being in contact at a particular position on said the or each face with the ground.

In embodiments, the contact determination system includes a detection unit. In embodiments, the detection unit includes a sensor system to provide information (e.g. digital information or a signal) based on said physical contact. The sensor system may be implemented as one or more of: a mechanical sensor (e.g. a switch that is tiggered when the threshold is exceeded); a camera system; an optical sensor, and; other suitable sensor.

In embodiments, the sensor system provides said information to electrical circuitry, which determines if the threshold has been crossed based on said information. In embodiments, the electrical circuitry implements said control of the user interface and/or the electrical energy (e.g. by control of an electrically operated switch in the transmission circuit or by control of the power supply). It will be understood that the components of the contact determination system may be located partially (e.g. where appropriate distributed on other components of the apparatus) or fully on the return unit.

In embodiments, the detection unit includes an actuator a position of the actuator being determined by the sensor system. By implementing a mechanical actuator-based system the contact determination unit may be cost effective. The actuator may be arranged to directly abut the ground.

In embodiments, with the actuator in a first position the return electrode is determined as not having sufficient physical contact with the ground and with the actuator in a second position the return electrode is determined as having sufficient in physical contact with the ground.

In embodiments, the actuator is actuated by the ground from the first position to the second position as the return electrode is inserted into the ground or as a body of the return unit is connected to the return electrode which is inserted into the ground.

In embodiments, the actuator is actuated by the ground from the second position to the first position as the return electrode is displaced from being: inserted into the ground, or; On the instance of a flat plate electrode that rests on the ground) arrange to abut a surface of the ground.

In embodiments, an actuator is arranged to apply a pull-out force to the return electrode when inserted into the ground. By implementing the actuator to apply a pulling force to the return electrode when it is inserted into the ground, it may be ensured that the return electrode is both in physical contact with the ground and is firmly inserted in the ground.

In embodiments, the return electrode is removably connected to the body and the contact determination system is at least partially arranged on the body. With such an arrangement the detection unit and/or electrical circuitry may be arranged distal the return electrode which may prevent damage from the high voltage electrical energy, moreover the return electrode may be conveniently replaced without disturbing the contact determination system.

In embodiments, the detection unit is arranged to be above ground when the return electrode is inserted into the ground. It may be advantageous not to have the detection unit (e.g. the mechanical sensor) arranged in the ground since it may be susceptible to damage when subject to subterranean conditions.

In embodiments, the detection unit is arranged on the return electrode, e.g. on a tip or side surface. With such an implementation the electrical circuitry may be implemented with high accuracy.

In embodiments, with the detection unit implemented as a camera system, an image processing system is operable to process an image of the return electrode to determine if it is inserted into the ground. With a camara system to determine physical contact, e.g. by determining if a periphery of a portion of the return electrode proximal the ground surface to air interface is touching the surface of the ground, a convenient system that does not require mechanical actuators may be implemented, moreover.

The present disclosure provides use of the apparatus as disclosed herein for electrical treatment of a plant, e.g. to kill or weaken the plant. The use may implement any feature of the preceding embodiment or another embodiment disclosed herein.

The present disclosure provides a return unit of the apparatus of any preceding embodiment or another embodiment disclosed herein. In embodiments, the return unit comprises a contact determination system arranged to determine an amount of physical contact between the return electrode and the ground.

The present disclosure also provides use of said return unit for electrical treatment of a plant, e.g. to kill or weaken the plant and/or with the apparatus of the preceding embodiment or another embodiment disclosed herein.

The present disclosure provides a method of treating a plant with electrical energy, the method comprising: applying electrical energy through a circuit comprising the plant an applicator electrode and a return electrode.

In embodiments, the method includes selecting a material forming the return electrode to have a thickness (t) based on a frequency of the electrical energy. In embodiments, the thickness (t) in m is defined by the relationship: t> D, wherein D = F is the frequency in Hz, P is the magnetic permeability in Him, which is calculated by multiplying the relative magnetic permeability Pr by the permeability constant Po in Him, and C is the electrical conductivity in S/m.

In embodiments, the method includes inserting a plate shaped return electrode into the ground.

In embodiments, the method includes electrically coupling a return electrode of a return unit to the ground; coupling a body to the return electrode to the return electrode to electrically couple the return electrode to a transmission circuit, and; applying electrical energy through the transmission circuit comprising the plant.

In embodiments, the method includes determining an amount of physical contact between the return electrode an ground has having crossed a threshold, and; attenuating the electrical energy or preventing transmission of the electrical energy.

The method may implement any feature of the preceding embodiments or another embodiment disclosed herein. The present disclosure provides electrical circuitry or a computer program to implement the method of the preceding embodiment or another embodiment disclosed herein.

The preceding summary is provided for purposes of summarizing some embodiments to provide a basic understanding of aspects of the subject matter described herein. Accordingly, the above-described features are merely examples and should not be construed to narrow the scope or spirit of the subject matter described herein in any way. Moreover, the above and/or proceeding embodiments may be combined in any suitable combination to provide further embodiments. Other features, aspects, and advantages of the subject matter described herein will become apparent from the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE FIGURES

Aspects, features and advantages of embodiments of the present disclosure will become apparent from the following description of embodiments in reference to the appended drawings in which like numerals denote like elements.

Figure 1 is a block system diagram showing embodiment electrical apparatus to attenuate plant growth.

Figure 2 is a schematic diagram showing the apparatus of figure 1.

Figure 3 is a schematic diagram showing an applicator unit of the apparatus of figure 1. Figure 4 is a schematic diagram showing an return unit of the apparatus of figure 1.

Figure 5 is a schematic diagram showing an electrical energy supply unit of the apparatus of figure 1.

Figure 6 is perspective view of a return electrode of the apparatus of figure 1. Figure 7 is a side cross-sectional view of the return electrode of figure 6.

Figure 8 is a perspective view of the return electrode of figure 6 and a driver for extraction of the return electrode from the ground.

Figure 9 is a perspective view of a return unit of the apparatus of figure 1 comprising a return electrode coupled to a body.

Figure 10 is a side cross-sectional view of the return unit of figure 9.

Figures 11 is a perspective view of a return unit of the apparatus of figure 1. Figures 12 and 13 are close up side views of the return unit of figure 11. DETAILED DESCRIPTION OF EMBODIMENTS Before describing several embodiments of the apparatus, it is to be understood that the system is not limited to the details of construction or process steps set forth in the following description. It will be apparent to those skilled in the art having the benefit of the present disclosure that the system is capable of other embodiments and of being practiced or being carried out in various ways.

The present disclosure may be better understood in view of the following explanations: As used herein, the term "plant" or "weed" may refer to an undesired plant in a human controlled setting, such as a farm field, garden, lawn or park. A weed may refer to a mulficellular photosynthetic eukaryote.

As used herein, the term "electrical arc" or "arc" may refer to an electrical breakdown of a gas that produces an electrical discharge. An arc is formed by an electrical current through a normally nonconductive medium such as air, and is characterized by a plasma, which may produce visible light. An arc discharge is characterized by a lower voltage than a glow discharge and relies on thermionic emission of electrons from the electrodes supporting the arc.

As used herein, the terrn "electrical energy" or "processed electrical energy" may refer to electrical energy supplied by an electrical energy supply unit and applied to the plant, e.g. through a transmission circuit. The electrical energy may comprise a periodic or aperiodic waveform, i.e. a waveform that continuously repeats with the repeating units therein having a constant or a varying period, e.g. a pulsed wave with a fixed duty cycle or a varying duty cycle. The shape of the repeating unit may be one of or a combination of one or more of the following forms: sine wave; saw-tooth wave; triangular wave; square wave; pulsed, e.g. DC pulsatile, half-wave rectified; other known form. The exact shape of the repeating unit may be an approximation of one of the aforesaid forms for reasons of distortion, e.g. overshoot/undershoot and the associated ringing and settle time. The repeating unit may be positive or negative or a combination thereof with respect to a selected reference value, which is typically earth or the DV of the voltage supply but may be another positive or negative voltage level. The frequency of the waveform may be above 25 Hz, 1 kHz, 5 kHz 10 kHz,18 kHz 01 25 kHz. It will be understood that when referring to the voltage of the electrical energy, when the electrical energy has a waveform, the voltage is in respect of a suitable quantity, such as RMS, peak or other. The same applies for other electrical quantities such as power and current.

As used herein, the term "electrical energy supply unit" may refer to any unit or system, including a distributed system, for generating and/or conditioning electrical energy for supply to a transmission circuit which, in use, incorporates a plant.

As used herein, the term "electrical circuitry" or "electric circuitry" or "electronic circuitry" or "circuitry" or "control circuitry" may refer to, be part of, or include one or more of the following or other suitable hardware or software components: an Application Specific Integrated Circuit (ASIC); electronic/electrical circuit (e.g. passive electrical components, which may include combinations of transistors, transformers, resistors, capacitors); a processor (shared, dedicated, or group); a memory (shared, dedicated, or group), that may execute one or more software or firmware programs; a combinational logic circuit. The electrical circuitry may be centralised on the apparatus or distributed, including distributed on board the apparatus and/or on one or more components in communication with the apparatus, e.g. as part of the system. The component may include one or more of a: networked-based computer (e.g. a remote server); cloud-based computer; peripheral device. The circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. The circuitry may include logic, at least partially operable in hardware.

As used herein, the term "processor" or "processing resource" may refer to one or more units for processing including as an ASIC, microcontroller, FPGA, microprocessor, digital signal processor (DSP) capability, state machine or other suitable component. A processor may include a computer program, as machine readable instructions stored on a memory and/or programmable logic. The processor may have various arrangements corresponding to those discussed for the circuitry, e.g. on-board and/or off board the apparatus as part of the system.

As used herein, the term "computer readable medium/media" or "data storage" may include conventional non-transient memory, for example one or more of: random access memory (RAM); a CD-ROM; a hard drive; a solid state drive; a flash drive; a memory card; a DVD-ROM; a floppy disk; an optical drive,. The memory may have various arrangements corresponding to those discussed for the circuitry/processor.

As used herein, the term "information carrying medium" may include one or more arrangements for storage of information on any suitable medium. Examples include: data storage as defined herein; a Radio Frequency Identification (RFID) transponder; codes encoding information, such as optical (e.g. a bar code or OR code) or mechanically read codes (e.g. a configuration of the absence or presents of cut-outs to encode a bit, through which pins or a reader may be inserted).

As used herein, the term "applicator unit" or "applicator" may refer to any suitable device for applying electrical energy to a plant, including by direct contact with the plant and/or spark transmission.

As used herein, the term "earth unit" or "return unit" may refer to any suitable device for receiving electrical energy from a circuit including the plant and optionally the ground to complete a transmission circuit, including by direct contact with the plant and/or spark transmission.

As used herein, the term "transmission circuit" may refer to a circuit, e.g. a closed predefined path, though which the electrical energy travels from the electrical energy supply unit and through a plant. It may include in order: the electrical energy supply unit, the applicator unit; the plant, and; the return unit. In suitable embodiments, the transmission circuit includes an above-ground portion of the plant, to which the electrical energy is applied by the applicator unit and a portion of the ground the plant is arranged in that interconnects the plant to the return unit.

As used herein, the term "apparatus" or "electrical apparatus" may refer to any combination of one or more of the following for treatment of a plant: electrical energy supply unit; electrical circuitry; applicator unit; applicator electrode; return unit; return electrode; transmission circuit.

Referring to figures 1 and 2, apparatus 2 to attenuate plant growth, comprises an electrical energy supply unit 4, an applicator unit 6 and a return unit 8. The electrical energy supply unit supplies electrical energy 10 around a transmission circuit 12, which includes the applicator unit 6, return unit 8.

The transmission circuit 12, when treating a plant, may include said plant 14. It will be understood that depending on the operative arrangement of the applicator unit and return unit, a return path of the transmission circuit 12 optionally includes other matter, such as proximal earth and fluid (e.g. air and moisture) to the plant.

The apparatus 2 includes electrical circuitry 16, which may implement a range of control operations. In embodiments, said circuitry 16 is operable to control the electrical energy supplied by the electrical energy supply unit 4 through the transmission circuit 12, as will be discussed.

Referring to figure 3, the applicator unit 6 is adapted to receive electrical energy 10 from the electrical energy supply unit 4 and to transmit said electrical energy 10 to the plant 14 (shown in figure 2). The applicator unit 6 comprises an applicator electrode 18. The applicator electrode 18 is electrically connected to the electrical energy supply unit 4 by an electrically conductive material, e.g. by wiring or solid material, which forms part of the transmission circuit 12.

The applicator electrode 18 is adapted to apply the electrical energy 10 to the plant 14. In embodiments, the applicator electrode 18 is arranged for direct contact with the plant 14. As used herein "direct contact" may refer to physical contact between the plant and electrode, and may be achieved by operatively arranging the electrode to be exposed from a body of the applicator. The applicator electrode 18 comprises an electrically conductive material e.g. copper, zinc, bronze, brass, aluminium or steel.

The geometric configuration of the applicator electrode 18 may be selected depending on the intended treatment regimen, for example: a rod for sweeping through areas of dense plants; a hook-shape for separating plants.

The applicator unit 6 comprises body 20 to carry the applicator electrode 18. The body 20 may be adapted to be held by a user or fixed to a chassis depending on the particular configuration of the apparatus 2 (e.g. adapted for domestic or agricultural implementation respectively).

In embodiments, which are not illustrated, the applicator electrode is implemented as a plurality of electrodes, e.g. for treatment of multiple plants at a given moment.

Referring to figure 4, the return unit 8 is adapted to receive electrical energy 10 from the applicator unit 6 via the plant 14 (shown in figure 2). The return electrode 22 is electrically connected to the electrical energy supply unit 4 by an electrically conductive material, e.g. by wiring or solid material, which forms part of the transmission circuit 12.

The return electrode 22 is adapted to provide a return for electrical energy 10 via the plant 14 to complete the transmission circuit 12. In embodiments, the return electrode 22 is arranged for direct contact with the ground 26 (shown in figure 4). As used herein "direct contact" may refer to physical contact between the ground and electrode, and may be achieved by operatively arranging the electrode to be exposed from a body of the return unit. The return electrode 18 comprises an electrically conductive material e.g. copper, zinc, bronze, brass, aluminium or steel.

The geometric configuration of the return electrode may be selected depending on the intended implementation of the apparatus, for example: an implement for insertion into the ground (e.g. for apparatus that in use remains in a generally fixed position), such as a rod or spike or a plate; an implement for movement along the ground (e.g. for apparatus that in use has a variable position), such as a flat plate or roller or rake, and; a combination of the aforesaid implementations.

The retum unit 8 comprises body 24 to carry the return electrode 22. The body 24 may be adapted to be held by a user or fixed to a chassis depending on the particular configuration of the apparatus 2 (e.g. adapted for domestic or agricultural implementation respectively).

In embodiments, which are not illustrated, the return electrode is implemented as a plurality of electrodes, e.g. for treatment of multiple plants at a given moment.

Generally, the apparatus 2 is arranged with the return electrode 22 arranged in operative proximity to the applicator electrode 18. Operative proximity may refer to a geometric arrangement to limit the path of the electrical energy 10 through the ground 26, which may be advantageous for reasons of efficient and/or electrical safety.

Referring to figure 5, the electrical energy supply unit 4 is arranged to supply processed electrical energy 10 to the transmission circuit 12. The electrical energy supply unit 4 includes a power supply 28 for supply of supply electrical energy 30. The power supply 28 may be implemented as one or more of the following: a battery; a fuel cell; a generator, including an internal combustion engine powered generator, which may be implemented with a dedicated internal combustion engine or a shared internal combustion engine for other agricultural equipment, e.g. a tractor, which is arranged to drive the generator; other like. The power supply 28 provides supply electrical energy 30, in alternating current (AC) or direct current (DC), including pulsated or with other form with a fixed quantity, e.g. in one or more or power; voltage; current; frequency; phase.

The electrical energy supply unit 4 includes an electrical energy processing unit 32 for processing of the supply electrical energy 30 to the electrical energy 10. The electrical energy processing unit 32 includes an electrical transformer 34 with appropriately configured windings, e.g. for step-up or step down, depending on the configuration of the supply electrical energy 30 and desired output of the electrical energy 10.

In variant embodiments, which are not illustrated, alternative step-up or step-down converters to the transformer are implemented, e.g. a boost converter, other amplifier topology. A step-up or step-down converter may also be obviated if the electrical energy is supplied in the desired form. For example, the transformer may be obviated if the electrical energy is supplied in the desired form by: the power supply or the power supply is replaced by an input unit to receive a commercial or domestic electrical supply (a mains supply).

Where the power supply 28 provides supply electrical energy 30 as AC (e.g. the power supply 28 is arranged as a generator) or the power supply 28 is omitted and there is an input unit comprising a circuit for receiving an electrical supply (e.g. from a mains electrical supply or other electrical supply) the electrical energy processing unit 32 includes a AC to DC converter (not illustrated) arranged to provide a DC current to a waveform shaping system, which may be referred to as a switching system 36. Where the power supply 28 provides supply electrical energy 30 as DC, e.g. a battery, an AC to DC converter is obviously obviated.

The electrical energy processing unit 32 includes a switching system 36 to generate the desired wave form (e.g. in shape and/or frequency) in the electrical energy supplied to the electrical transformer 34. The switching system 36 is implemented as an electrically operated switch (e.g. a MOSFET, relay, other transistor).

In variant embodiments of the electrical energy supply unit, which are not illustrated, the power supply (or electrical supply to the input unit) supplies electrical energy of the desired configuration. Accordingly, the electrical energy processing unit is obviated. In other embodiments, the power supply (or input unit) supplies electrical energy which only needs step-up or step-down, in which case the switching system is obviated but the transformer is maintained. In other examples the switching system is present but the step-up or step-down converter is omitted.

The electrical circuitry 16 implements a control algorithm to control the electrical energy 10, through the transmission circuit 12. Said control may implement control of one or more of the following electrical quantities: electrical potential between the applicator and return electrodes; electrical current control; frequency or duty control; phase.

In the embodiment of figure 5, the electrical circuitry 16 controls the switching system 33 to implement control of the voltage and current by pulse width modulation. The frequency is controlled by the rate of switching. In variant embodiments, which are not illustrated the electrical quantities can be controlled by other means, e.g. including by changing the taping of the electrical transformer (on the primary and/or secondary coil), which may be implemented as a variable transformer, by introducing capacitance and/or inductance in the transmission circuit.

Referring to figures 6 and 7, a first example of the return unit 8 includes the return electrode 22, which can be connected directly to the transmission circuit 12 thus obviating a body 24. The return electrode 22 is arranged as a plate 22 for insertion into the ground 26 (not illustrated in figure 6, but illustrated in figures 3 and 4).

The plate 22 extends in a longitudinal direction 100, which is counter to a direction of insertion into the ground 26. The plate 22 extends in a lateral direction 102, which is a direction perpendicular to a longitudinal direction 100, and in a thickness direction 104, which is perpendicular to the longitudinal direction 100 and the lateral direction 102.

The plate 22 includes a proximal end 40 and a distal end 42, wherein proximal is defined as relative to a tip 44. The proximal end 40 comprises the tip 44, which is an initial part of the plate 22 in contact with the ground during insertion. The distal end 42, which comprises a top surface 46. The top surface 46 is generally planar and extends perpendicular to the longitudinal direction 100. In this manner it may be impacted with a hammer (not illustrated) or like driver until the return electrode 22 is fully inserted into the ground 26. The proximal end 40 and distal end 42 are separated in the longitudinal direction 100. A central axis 106 extends in the longitudinal direction 100, from the tip 44 to the top surface 46.

The longitudinal dimension is about 20 cm. The lateral dimension is about 10 cm. The thickness dimension is about 0.5 cm. In variant emblements, which are not illustrated: the longitudinal dimension may be 5 -50 cm; the lateral dimension may be 5 -20 cm, and; the thickness dimension may be 0.2 -4 cm.

The plate 22 incudes opposed principal faces 34, 36 that and extend principally in the longitudinal 100 and lateral 102 directions. The principal faces 48, 50 are inclined to each other with respect to the depth direction 104, such that they have an acute angle 52 of 2.5 to 45 degrees or 5 to 25 degrees.

In variant embodiments, which are not illustrated, the principal faces are alternatively arranged, including as: parallel; with portions parallel and inclined.

A front periphery 54, including the tip 44, of the plate 22 that faces the ground during insertion is profiled to facilitate insertion into the ground. The front periphery 54 may be defined as the area of the plate 22 that is visible when looking at the plate 22 in the longitudinal direction 100. The profiling comprises a sharpening with inclined opposed linear edges. In variant embodiments, the sharpening comprises other arrangements including: curved; combinations of linear and curved; other suitable formations.

Between the proximal end 40 and distal end 42 is a portion 56 of maximum lateral dimension. The lateral dimension of the plate 22 increases progressively from the tip 44 with increasing longitudinal direction 100 to the portion 56 of maximum lateral dimension. The lateral dimension of the plate 22 increases progressively from the top surface 46 with decreasing longitudinal direction 100 to the portion 56 of maximum lateral dimension.

The portion 56 of maximum lateral dimension is provided as discussed for the front periphery 54. In the example, the front periphery 54 extends to the portion 56 of maximum lateral dimension, hence the profiling for insertion is continuous between these two regions.

In variant embodiments, which are not illustrated, the plate is alternatively arranged, including: the same lateral dimension from tip to top surface; the portion of maximum lateral dimension may extend to the tip or the top surface; the front periphery and/or the periphery of the portion of maximum lateral dimension is not provided for insertion.

The thickness of the plate 22 in the depth direction 104 decreases at an edge region 58. The edge region 58 is distal the central axis 106 and extends in the lateral direction 102 to the portion 56 of maximum lateral dimension. Within the edge region 58 said thickness decreases with increasing lateral distance from the central axis 106.

In variant embodiments, which are not illustrated, the plate is alternatively arranged, including: the edge region is omitted.

The plate 22 includes a first engagement member 60 for engagement with a driver (not shown in figure 6 or 7 but it could for example include a rim of a spade of other like tool) to extract the plate 22 from the ground. The first engagement member 60 is arranged as a slot on both of the principal faces 48, 50. The slot extends with a major axis in the lateral direction 102 and into the plate 22 in the depth direction.

In variant embodiments, which are not illustrated the first engagement member is alternatively arranged, including: as a ridge; as multiple discrete ridges and/or slots, and; on one of the principal faces only, or elsewhere on the plate.

Referring to figure 6 to 8, the plate 22 includes a second engagement member 62 for engagement with a driver 64 to extract the plate 22 from the ground. The second engagement member 62 is arranged as a threaded cavity 66 extending in the longitudinal direction 100 from the top surface 46. The driver 64 includes a third engagement member 68 for engagement with the second engagement member 62. In particular, the third engagement member 68 of the driver 64 is arranged as a complimentary threaded extension for insertion and threaded engagement with the cavity 66. As indicated, with the third engagement member 68 of the driver 64 engaged with the second engagement member 62, the driver 64 can be used to lever the plate 22 from the ground.

The second engagement member includes an opening 70, such that the cavity 66 is a through hole. Debris from the ground in the cavity 66 may be cleared via the opening 70.

In variant embodiments, which are not illustrated the second engagement member is alternatively arranged, including: a protrusion to fit in a recess of the driver; a press fit with the driver; a square or other rotationally locking shape, and; the opening is omitted.

The minimum thickness (t) in m of the plate 22 can be determined by the relationship: t > D, wherein D - , F is the frequency in Hz, P is the magnetic permeability in Him, which is calculated by multiplying the relative magnetic permeability pi by the permeability constant po in Him, and C is the electrical conductivity in S/m.

Referring to figure 7, said minimum thickness is at a position of the plate 22 that is proximal the tip 44, but distal the profiling of front periphery 54. Since the plate is wedge shaped, it will be understood that the thickness is greater elsewhere. It is also to be noted that the narrowing in thickness caused by the first engagement members 60 may be selected to be greater than said minimum thickness.

In general the minimum thickness applies everywhere except for any profiling of the periphery to aid insertion/extraction. Generally said minimum thickness applies to all of the plate 22 or a substantial portion e.g. at least 80 or 90%.

In variant embodiments, which are not illustrated, with alternative profiling of the plate as the principal faces being parallel to each other, said minimum thickness may be the distance between the principal faces.

Plate 22 has a surface area S in cm2 of greater than 315. 10,000, F is the frequency in Hz, p is the density in kg/cm3, R is the electrical resistivity in 0.m, S is the specific heat capacity in J.Kg-1.K1. The surface area includes the principal faces 48, 50, peripheries and edge regions 58.

Referring to figures 9 and 10, a second example of the return unit 8 comprises: a body 24 comprising an electrical connection to the transmission circuit 12 (not illustrated in figures 9 and 10), and; first example of the return unit as discussed above (which is associated with of figures 6 to 9) incorporated as a return electrode 22.

In the second example of the return unit 8 the return electrode 22 and the body 24 are couplable in a coupled configuration (figures 9 and 10) and separable in a decoupled configuration (figures 6 to 8 for electrode only). In the coupled configuration, the body 24 electrically connects the return electrode 22 to the transmission circuit 12 (see figure 5 for transmission circuit).

The return unit 8 includes a coupling system 72 operably to removably couple the return electrode 22 to the body 24, and which is disposed on both of said components. The coupling system 72 both: mechanically couples the return electrode 22 to the body 24, and; and electrically couples the return electrode 22 to the transmission circuit 12 via an electrical connection to the transmission circuitry 12 of the body 24 as will be discussed.

The coupling a system 72 comprises the second engagement member 62 of the return electrode 22. The coupling system 72 comprises a fourth engagement member 74, which is part of the body 24 and acts as an electrical terminal 76. The fourth engagement member 74 is arranged as an extension comprising a threaded connection. It will be understood that the coupling system 72 couples as discussed previously for the third engagement member 68 of the driver 64, that is, the with the second engagement member 62 engaged with the fourth engagement member 74 the body 24 is rotated about the central axis 32 of the return electrode 22 to transition from the decoupled configuration to the coupled configuration.

The electrical terminal 76 is electrically coupled to the transmission circuit 12. Although not explicitly illustrated, this may be accomplished by the connection of wire directly to the terminal 76 or via an intermediate terminal or other suitable means.

With reference to figures 9 and 10, it will be understood that when the return electrode 22 is inserted in the ground, and with the return unit 8 in the coupled configuration, the second member 62 an fourth engagement member 74 are engaged below the ground.

In variant embodiments, which are not illustrated, the coupling system is alternatively arranged, including: configured with an interference fit connection; a bayonet connection; the fourth engagement member is arranged as a cavity and the third engagement member is arranged as an extension, and; other suitable connection. The body and return electrode may be permanently coupled.

Although the coupling system 72 is illustrated as both mechanically and electrically coupling the body 24 and return electrode 22, the two functions may be achieved by dedicated separate couplings, e.g. the coupling system as discussed above may purely provide a mechanical coupling, and its engagement in the coupled configuration may electrically connect separate electrical terminals.

Referring to figures 9 and 10, a housing 78 of the body 24 is arranged to extend around a coupled return electrode 22, such that the top surface 46 and any portion of the principal faces 48, 50 (or other portion) which is exposed when the return electrode 22 is inserted in the ground is covered.

The housing 78 has a ground engaging portion 80, which presents a planar surface to engage the ground 26 (not illustrated in figures 9 and 10) in the coupled configuration. The ground engaging portion 80 is shaped to resist insertion of the body 24 into the ground 26 under normal conditions (e.g. when subject to the screwing force applied by a user to couple the components, or via a pressing force applied by a foot of a user).

Referring to figure 10, the return unit 8 implements a coupling detection system 82 to determine if the return electrode 22 and body 24 are in the coupled configuration or in the decoupled configuration.

The coupling detection system 82 includes a detection unit 84, which includes a sensor system 86 to provide information based on the coupling configuration. The sensor system 86 is implemented as a mechanical sensor 88 that is triggered by an actuator (not illustrated) which is arranged in the housing 60.

In variant embodiments, which are not illustrated, the detection unit has alternative arrangements including one or more of: a camera system; an optical sensor; a sensor arranged to detect an open circuit caused by the return electrode being separate from the return unit, and; other suitable sensor.

The coupling detection system 82 includes the control electrical circuitry 16. The sensor system 86 provides said information to the electrical circuitry 16, which determines the coupling configuration based on said information. The associated control electrical circuitry 16 can be arranged onboard the return unit 8, or distributed on other components of the apparatus 2.

If the coupling detection system 82 determines that the return unit 10 is in the decoupled configuration, it controls the transmission of the electrical energy 10 through the transmission circuit 12, for example, the electrical energy 10 may be attenuated or prevented. In particular, the electrical circuitry 16 implements said control of the electrical energy 10 by control of an electrically operated switch (not illustrated) in the transmission circuit 12.

In variant embodiments, which are not illustrated: the coupling detection system alternatively or in addition provides a notification via a user interface to a user that the return unit is in the decoupled configuration, which may include an instruction to replace and/or couple the return electrode; the electrical circuitry can alternatively control the electrical energy by direct control of the power supply, the switching system, or another suitable arrangement; the detection system may provide a signal when in the decoupled configuration (e.g. it is arranged as a switch that is immediately triggered when decoupling occurs) and the signal is provided directly to the switching system (or other equivalent) hence the electrical circuitry may be omitted.

Referring to figure 10, the return unit 8 includes a cooling system 90 arranged to cool the return electrode 26 in the coupled configuration.

In a first example the cooling system 90 is implemented via a conductive heat transfer by using a large mass of the coupled terminal 74 of the coupling system 72 to conduct heat from the return electrode 22.

In variant embodiments, which are not illustrated: an alternative conducive member is connected to the return electrode; the terminal may be connected to a further conductive member to act as an additional heatsink.

In a second example, referring to figure 9, the cooling system 90 is implemented as apertures 92 in the housing 60 for circulation of air to convectively cool the terminal 72 and/or return electrode 22.

Referring to figure 10, the return unit 8 comprises a temperature control system 94 to determine a temperature of the return electrode 22. The temperature control system 94 can determined the temperature for data collection or display to a user. In a particular example, the temperature control system 94 determines if the temperature has crossed a threshold. e.g. it has exceeded a safe operating temperature.

The temperature control system 94 includes a sensor system 96 to provide information based on a temperature of the return electrode 22. The temperature sensing system 96 is conductively coupled to the terminal 74. In particular, it is incorporated as part of the body 24, within the housing 78. The sensor system 96 is implemented as a temperature sensor, e.g. a thermocouple or thermopile. The sensing system 96 is electrically isolated from the transmission circuit 12.

In variant embodiments, which are not illustrated, the temperature sensing system includes: other temperature sensors, including an infra-red camera; the temperature sensing system may be implemented as a plurality of sensors, and; the temperature sensing system is alternatively arranged, including directly on the return electrode.

The temperature control system 94 includes the control electrical circuitry 16. The temperature sensing system 96 provides said information to the electrical circuitry 16, which determines the threshold as crossed based on said information. The associated control electrical circuitry 16 can be arranged onboard the return unit 8, or distributed on other components of the apparatus 2.

If the temperature control system 94 determines that the temperature threshold is crossed, it controls the transmission of the electrical energy 10 through the transmission circuit 12, for example, the electrical energy 10 may be attenuated or prevented. In particular, the electrical circuitry 16 implements said control of the of the electrical energy 10 by control of an electrically operated switch (not illustrated) in the transmission circuit 12.

In variant embodiments, which are not illustrated: the temperature control system alternatively or in addition provides a notification via a user interface to a user that the return unit has crossed a temperature threshold, which may include an instruction to replace and/or move the return electrode; the electrical circuitry can alternatively control the electrical energy by direct control of the power supply, the switching system, or another suitable arrangement.

Referring to figures 9 and 10, the return unit 8 includes a contact determination system 110 which is arranged to determine an amount of physical contact between the return electrode 22 and the ground 26 (not illustrated in figure 9 and 10). The contact determination system 110 can determine if said amount of physical contact has crossed a threshold, e.g. there is insufficient contact with the ground for a suitable electrical connection as will be discussed The contact determination system 110 includes a detection unit 112. The detection unit 112 includes a sensor system 114 to provide information based on said physical contact. The sensor system 114 is incorporated as part of the body 24, within the housing 78. The sensor system 114 is implemented as a mechanical sensor.

The contact determination system 110 includes the control electrical circuitry 16. The sensor system 114 provides said information to the electrical circuitry 16, which determines the threshold as crossed based on said information. The associated control electrical circuitry 16 can be arranged onboard the return unit 8, or distributed on other components of the apparatus 2.

If the contact determination system 110 determines that the threshold is crossed, it controls the transmission of the electrical energy 10 through the transmission circuit 12, for example, the electrical energy 10 may be attenuated or prevented. In particular, the electrical circuitry 16 implements said control of the electrical energy 10 by control of an electrically operated switch (not illustrated) in the transmission circuit 12.

In variant embodiments, which are not illustrated: the contact determination system alternatively or in addition provides a notification via a user interface to a user that the threshold is crossed, which may include an instruction to replace and/or re-insert the return electrode; the electrical circuitry can alternatively control the electrical energy by direct control of the power supply, the switching system, or another suitable arrangement; the detection system may provide a signal when the threshold is crossed (e.g. it is arranged as a switch that is immediately triggered when the threshold is crossed) and the signal is provided directly to the switching system (or other equivalent) hence the electrical circuitry may be omitted.

The detection unit 110 includes an actuator 116, which forms part of the housing 78 of the body 24. A position of the actuator 116 is determined by the sensor system 114. The actuator 116 implements the ground engaging portion 80 of the housing 78, and hence in use directly abuts the ground 26. The actuator 116 is slidably coupled on the body 24 in the longitudinal direction 100.

With the actuator 116 in an extended first position (as shown in figures 9 and 10) the return electrode 22 is determined as not having sufficient physical contact with the ground. With the actuator 116 in a retracted second position (not illustrated) the return electrode 22 is determined as having sufficient in physical contact with the ground. The actuator 116 is biased with a biasing member (which is not illustrated e.g. a spring) to the first position.

It will be understood that as a return electrode 22, which is fully inserted in the ground 26, is coupled with the body 24 into the coupled configuration the actuator 116 is transitioned from the first position to the second position. Moreover, if the return electrode 22 with a body 24 coupled thereto in the couple configuration, has the return electrode 22 progressively inserted into the ground, the actuator 116 is transitioned from the first position to the second position.

The biasing member implements a pull-out force through the actuator 116 onto an inserted return electrode 22. In this manner if the return electrode 22 is loosely inserted in the ground, the actuator will transition from the second position to the first position, and in doing so pull the return electrode 22 out of the ground 26. It will be understood that as the return unit is transitioned from a coupled and inserted position to a decoupled position, the actuator will also transition from the second position to the first position.

In the example, a level of physical insertion of the return electrode 22 in the ground 26 determines physical contact between the return electrode and the ground. The threshold may be determined as crossed when the top surface 46 of the return electrode 22 exceeds (i.e. protrudes above) ground surface level. Alternatively the threshold may be determined as crossed when a distance of the top surface 46 below the ground surface level reduced below a predetermined minimum amount.

In the example, the pull-out force required to pull and inserted return electrode 22 from the ground also determines physical contact between the return electrode and the ground. A threshold may be set by selecting a biasing member with a particular biasing force.

In variant embodiments, which are not illustrated: an alternative sensor system may be implemented to determine the position of the actuator, e.g. an optical sensor; the actuator incorporates the sensor, e.g. the actuator is the mechanical switch; the detection unit is alternatively implemented with a camera system (e.g. an infra-red camera) and an image processing system operable to process an image of the return electrode to determine if it is inserted into the ground, e.g. the camara system to determine physical contact by determining if a periphery of a portion of the return electrode proximal the ground surface to air interface is touching the surface of the ground, and; in embodiments, wherein the return unit comprises only the return electrode and no couplable body, the contact determination system is implemented as a sensor system as discussed above on the body of the return electrode, for example a mechanical sensor arranged on the tip or principal faces of the return electrode may be implemented to determined contact.

In variant embodiments, which are not illustrated, were the detection unit is arranged as a contact determination system implemented as a sensor system on the body of the return electrode, the determination of one or more of the sensors not being in immediate contact with the ground may determine said threshold as crossed.

A method of implementing the return unit 8 comprises the following steps: Step 1: insert return electrode 22 into ground 26. This step may be achieved by manually pressing the return electrode 22 into the ground or via an impactor, such as a hammer, to impact the top surface 46.

Step 2: couple the body 24 to the return electrode 22. This step may be achieved by placing the body 24 over the exposed portion of the inserted return electrode 22. The return unit may then be transitioned to the coupled configuration (shown in figures 9, 10) by and engaging the second engagement member 62 with the third engagement member 76 of the body 24. In the embodiment of a threaded connection the body 24 is rotated around the return electrode 22 about the central axis 106 until coupling is achieved, which may be determined by the coupling detection system 82.

Step 3: apply electrical energy 10 through the return unit 8. The electrical energy 10 may be applied through (and when in being applied through maintained as applied through) the return unit 8, and in particular through the return electrode 22 and terminal 74, based on one or more of the following conditions: the coupling detection system 82 determines the coupled configuration; the contact determination system 110 determines sufficient physical contact between the return electrode 22 and the ground 26, and; the temperature control system 94 determines the temperature of the return electrode 22 not to have crossed a safe threshold.

Step 4: cool the return electrode 22. The cooling system 90 may cool the return electrode 22 as the electrical energy 10 is transmitted therethrough, particular to increase an envelope of operation by acting to prevent the safe temperature threshold being crossed.

Step 5: decouple the body 24 and the return electrode 22. To decouple the return unit 8, the body 24 is decoupled from the return electrode 22 by disengaging the coupling system 72, e.g. by rotating the threaded connection in a direction counter to that for coupling.

Step 6: extract the return electrode 22 from ground 26. The inserted return electrode 22 is extracted from the ground using the first engagement member 60 and a driver (not illustrated) or via the second engagement member 62 and the driver 64.

Referring to figure 11 in a third example, the return unit 8 includes an assembly, which may implement other components of the apparatus 2. The return electrode 22 implemented as a plurality of individual units, each of which may implement any feature of the return electrode as discussed for the first example of the return unit 8 in association with figures 6 and 7.

The return unit 8 includes a lever 120 which is used to move the return electrode 22 including to insert and extract the return electrode 22 from the ground The return unit 8 may include the temperature control system 94 as discussed for the second example of the return unit 8. The return unit 8 may include a contact determination system 110 as discussed for the second example of the return unit 8. Figures 12 and 13 show the actuator 116 of the contact determination system 110 and the return electrode 22 arranged as a single blate or arranged as a plurality of teeth respectively.

It will be appreciated that any of the disclosed methods (or corresponding apparatuses, programs, data carriers, etc.) may be carried out by either a host or client, depending on the specific implementation (i.e. the disclosed methods/apparatuses are a form of communication(s), and as such, may be carried out from either 'point of view', i.e. in corresponding to each other fashion). Furthermore, it will be understood that the terms "receiving" and "transmitting" encompass "inputting" and "outputting" and are not limited to an RF context of transmitting and receiving radio waves. Therefore, for example, a chip or other device or component for realizing embodiments could generate data for output to another chip, device or component, or have as an input data from another chip, device or component, and such an output or input could be referred to as "transmit" and "receive" including gerund forms, that is, "transmitting" and "receiving", as well as such "transmitting" and "receiving" within an RF context.

As used in this specification, any formulation used of the style "at least one of A, B or C", and the formulation "at least one of A, B and C" use a disjunctive "or" and a disjunctive "and" such that those formulations comprise any and all joint and several permutations of A, B, C, that is, A alone, B alone, C alone, A and B in any order, A and C in any order, B and C in any order and A, B, C in any order. There may be more or less than three features used in such formulations.

In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word 'comprising' does not exclude the presence of other elements or steps then those listed in a claim. Furthermore, the terms "a" or "an," as used herein, are defined as one or more than one. Also, the use of introductory phrases such as "at least one" and "one or more" in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an." The same holds true for the use of definite articles. Unless stated otherwise, terms such as "first" and "second" are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The mere fad that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

Unless otherwise explicitly stated as incompatible, or the physics or otherwise of the embodiments, example or claims prevent such a combination, the features of the foregoing embodiments and examples, and of the following claims may be integrated together in any suitable arrangement, especially ones where there is a beneficial effect in doing so. This is not limited to only any specified benefit, and instead may arise from an "ex post facto" benefit. This is to say that the combination of features is not limited by the described forms, particularly the form (e.g. numbering) of the example(s), embodiment(s), or dependency of the claim(s). Moreover, this also applies to the phrase "in one embodiment", "according to an embodiment" and the like, which are merely a stylistic form of wording and are not to be construed as limiting the following features to a separate embodiment to all other instances of the same or similar wording. This is to say, a reference to 'an', 'one' or 'some' embodiment(s) may be a reference to any one or more, and/or all embodiments, or combination(s) thereof, disclosed. Also, similarly, the reference to "the" embodiment may not be limited to the immediately preceding embodiment.

As used herein, any machine executable instructions, or compute readable media, may carry out a disclosed method, and may therefore be used synonymously with the term method, or each other.

The foregoing description of one or more implementations provides illustration and description, but is not intended to be exhaustive or to limit the scope of the invention to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of various implementations of the present disclosure.

LIST OF REFERENCES 2 Electrical apparatus 4 Electrical energy supply unit 28 Power supply 32 Electrical energy processing unit 34 Electrical transformer 36 Wave form shaping/Switching system 6 Applicator unit 18 Applicator electrode Body 8 Return unit 22 Return electrode (plate) Proximal end 44 Tip 54 Front periphery 42 Distal end 46 Top surface 48, 50 Principal faces 52 Angle 56 Portion of maximum lateral dimension 58 Edge region First engagement member 62 Second engagement member 66 Cavity Opening 64 Driver 68 Third engagement member 24 Body 72 coupling system 74 Terminal 76 Fourth engagement member 78 Housing Ground engaging portion 82 Coupling Detection system 84 Detection unit 86 Sensor system 88 Mechanical sensor 16 Electrical circuitry Cooling system 92 Apertures 74 Terminal 94 Temperature control system 96 Sensor system 16 Electrical circuitry Contact determination system 112 Detection unit 114 Sensor system 116 Actuator 16 Circuitry Electrical energy Supply electrical energy 12 Transmission circuit 16 Electrical circuitry 14 Plant 26 Ground Longitudinal direction 102 Lateral direction 104 Thickness direction 106 Central axis

Claims

CLAIMS1. Electrical apparatus to kill a plant or at least attenuate plant growth, the apparatus comprising: an electrical energy supply unit; an applicator unit comprising an applicator electrode; a return unit comprising a return electrode; a contact determination system, and; the electrical energy supply unit arranged to apply electrical energy through a transmission circuit comprising the applicator electrode, and the return electrode, wherein the contact determination system is arranged to determine if an amount of physical contact between the return electrode and the ground has crossed a threshold, and, if said threshold is crossed, to attenuate the electrical energy or prevent transmission of the electrical energy through the transmission circuit.
2 The electrical apparatus of claim 1, wherein said physical contact is determined by one or more of the following conditions: a level of insertion of the return electrode into the ground; a pull out force required to extract the return electrode from the ground; a position on the surface of the return electrode being in direct contact with the ground.
3 The electrical apparatus of either of claims 1 or 2, wherein a contact determination system includes a detection unit that includes a sensor system to provide information based on the physical contact.
4. The electrical apparatus of claim 3, wherein the detection unit includes an actuator, a position of the actuator being determined by the sensor system.
The electrical apparatus of claim 4, wherein with the actuator in a first position the return electrode is determined as not having sufficient physical contact with the ground and with the actuator in a second position the return electrode is determined as having sufficient in physical contact with the ground.
6 The apparatus of claim 5, wherein the actuator is actuated by the ground from the first position to the second position as the return electrode is inserted into the ground or as a body of the return unit is connected to the return electrode which is inserted into the ground.
7 The apparatus of any of claims 5 or 6, wherein the actuator is actuated by the ground from the second position to the first position as the return electrode is displaced from being: inserted into the ground, or; arrange to abut a surface of the ground.
8 The apparatus of any of claims 5 to 7, wherein an actuator is arranged to apply a pull-out force to the return electrode when inserted into the ground.
9. The apparatus of any preceding claim, wherein the return electrode is removably connected to a body and the contact determination system is at least partially arranged on the body.
10. The apparatus of any preceding claim, wherein the contact determination system is at least partially arranged on the return electrode.
11. The apparatus of any preceding claim, wherein the return electrode is arranged as a plate with an angled periphery for insertion into the ground.
12. The apparatus of any preceding claim, wherein the return electrode has a thickness (t) in m that is defined by the relationship: t > D, wherein D = , F is the frequency in Hz, P is the magnetic permeability in which is calculated by multiplying the relative magnetic permeability pr by the permeability constant po in H.m-1, and C is the electrical conductivity in S.m-1.
13 The apparatus of any preceding claim, wherein the return unit comprises a temperature control system to determine if a temperature of the return electrode has crossed a threshold, and to prevent or attenuate transmission of the electrical energy through the transmission circuit if a temperature of the return electrode is determined to have crossed a threshold.
14. The apparatus of claim 13, wherein the temperature control system comprises a temperature sensing system, which is conductively coupled to the return electrode.
15. The electrical apparatus of any preceding claim, wherein, the return unit comprises: a body to receive an electrical connection to the transmission circuit, the return electrode and body couplable in a coupled configuration and separable in a decoupled configuration, wherein in the coupled configuration, the body electrically connecting the return electrode to the transmission circuit.
16. The electrical apparatus of claim 15, wherein the return electrode and body are arranged with the return electrode to be insertable into the ground in the decoupled configuration, and to be maintained inserted in the ground as the return unit is transitioned to the coupled configuration.
17 The electrical apparatus of any of claims 15 to 16, wherein the return unit comprises a coupling detection system arranged to determine if the return electrode and body are in the coupled configuration or the decoupled configuration, and to attenuate or prevent transmission of the electrical energy though the transmission circuit if the decoupled configuration is determined.
18. The electrical apparatus of any of claims 15 to 17, comprising a coupling system, which is arranged to mechanically couple the return electrode to the body and is a removable coupling, wherein the coupling system electrically couples the return electrode to the transmission circuit via the body.
19. The return unit of claim 18, wherein the coupling system is arranged as an engagement member of the body to engage with a complimentary engagement member of the return electrode, wherein the engagement members electrically couple the return electrode to the transmission circuit and are arranged to be at least partially below ground in the coupled configuration.
20. The electrical apparatus of any of claim 15 to 19, wherein the return unit includes a cooling system arranged to cool the return electrode in the coupled configuration, wherein the cooling system comprises a conductive heat transfer based system, wherein the conductive heat transfer system comprises a terminal of the body which, with the return unit in the coupled configuration, electrically couples the return electrode to the transmission circuit and/or mechanically couples the return electrode to the body.
21. The electrical apparatus of claim any preceding claim comprising electrical circuitry arranged to prevent or attenuate the electrical energy through the transmission circuit based on one or both more of the following conditions: a coupling detection system determining a the body and return electrode are arranged in a decoupled configuration, and; a temperature control system determining a temperature of the return electrode has crossed a threshold.
22. Use of the apparatus of any preceding claim for treatment of a plant.
23. A return unit for electrical apparatus to kill a plant or at least attenuate plant growth, the apparatus arranged to apply electrical energy through a transmission circuit comprising an applicator electrode, a plant, and the return unit, the return unit comprising: a contact determination system arranged to determine an amount of physical contact between the return electrode and the ground.
24. Use of the return unit of claim 23 for electrical treatment of a plant.
25. A method of treating a plant with electrical energy applied though a transmission circuit including the plant, an applicator electrode and the return electrode, the method comprising: determining an amount of physical contact between the return electrode an ground has having crossed a threshold, and; attenuating the electrical energy or preventing transmission of the electrical energy.