DE102021204664A1 - Determination of properties of vegetation samples using electrical quantities - Google Patents

Abstract

The invention relates to a method for examining a vegetation sample (42), comprising: - compressing the vegetation sample (42) so that it assumes a predetermined shape; - placing the compressed vegetation sample (42) in an electrode arrangement (34) and applying a voltage the electrode arrangement (34);- determining at least one electrical variable when the voltage is applied;- determining at least one property of the vegetation sample (42) on the basis of the electrical variable.An examination arrangement (10) for carrying out the method is also disclosed.

Description

The invention relates to a method and an arrangement for examining vegetation samples. In particular, the method is aimed at determining a (preferably dry) biomass of a vegetation sample, for which the vegetation sample is exposed to a powered electrode arrangement.

In the state of the art, there are various approaches for determining the properties of vegetation samples. Typically these are used for monitoring plant growth in agriculture or for research purposes. The biomass is often determined and, more precisely, the dry biomass is determined as a property of the vegetation.

Many of the common measuring methods can only be reliably carried out in laboratories, i.e. they are not suitable for in-situ measurements in the open field. The measurement cannot therefore be carried out near or at the growing location of the vegetation, which increases the expenditure of time and costs.

In situ measurements of plant physiological parameters, to which this disclosure is directed as a preferred use case, are also made for the development and/or validation of remote sensing sensors, as well as algorithms, methods, missions, data and derived information products used for remote sensing. In order to be able to provide the required in-situ data, in particular for the calibration and validation of remote sensing data, extensive measurement campaigns are required, which are associated with personnel costs and for which measurement strategies have to be developed. Work within the framework of vegetation field campaigns may be time-consuming and exhausting. As a result, measurements can be incorrect and thus have a negative impact on the quality of the remote sensing sensors.

From the DE 10 2007 058 836 A a microwave resonator is known which works non-invasively or non-destructively (ie the vegetation is not significantly damaged by taking the measurement). A vegetation sample can be placed in or enclosed by the microwave resonator and a resonance response of the sample is detected. The biomass is determined using the resonance response and previously stored calibration data.

The object of the invention is to enable the properties of a vegetation sample, in particular its moisture content and/or biomass, to be determined reliably and preferably in situ.

This object is solved by the subject matter of the appended independent claims. Advantageous embodiments are specified in the dependent claims.

It was recognized that previous in-situ determination of vegetation properties did not always provide sufficiently reliable results. The measuring devices used for this, such as the above microwave generator, cannot always be operated intuitively.

In addition, a non-invasive vegetation examination (for example with the above microwave generator) makes it difficult to establish comparable measurement conditions. It cannot be reliably guaranteed that comparable vegetation components are always selected and/or included in the measuring device in a comparable manner. This limits the validity of calibration data that are based on a specific target state of the measurement (i.e. also on a target state of the selected vegetation sample and its (target) arrangement in a measuring device).

The invention generally proposes examining a vegetation sample (in short: sample) using an electrode arrangement to which a voltage is applied. For this purpose, the sample is preferably taken up in an examination arrangement that can be transported and/or manually operated and/or used at the site of the vegetation and pressed into a form suitable for the examination. It has been shown that such a measurement method can be implemented in situ with little effort and with good reproducibility.

The vegetation sample is preferably processed beforehand outside or inside the examination arrangement, for example crushed or dried. This allows the vegetation sample to be homogenized. Through the subsequent pressing, it can assume a standardized or repeatable state, which increases the meaningfulness and comparability of measurement results.

Drying can additionally or alternatively be achieved by pressing. This allows moisture to be pressed out of the sample and thus removed, which is equivalent to drying.

In general, drying cannot be a primary goal, but can be accepted as a side effect of pressing or other processing steps, so to speak. In other words, drying can occur as an inevitable side effect of sample processing. Should e.g. B. the sample moisture can be determined, it is advantageous to determine and take into account the loss of moisture, in particular as a result of pressing or, in general, the processing of the sample. For this purpose, sample weights can be measured before and after processing (in particular before and after pressing and/or before and after crushing). The difference can correspond to the mass of moisture released as a result of processing. This can be taken into account when determining a final result (eg the moisture content), for example by adding it to an (electrically) measured moisture and/or to a moist mass fraction determined by measurement.

As an alternative or in addition, a loss of mass that has occurred as a result of the machining can take place by catching escaping liquid. This can also be weighed, for example, and taken into account as a wet mass fraction in the same way as above.

According to a preferred variant, a loss of moisture in the sample as a result of both crushing and pressing is determined. The resulting total moisture loss and in particular a mass fraction associated therewith can be taken into account when determining the sample moisture.

In particular, processing can achieve comparability with a sample state that was present when the comparison or calibration data described below was determined. The validity and applicability of these comparison or calibration data is thus increased accordingly, since they were obtained under comparable measurement conditions and, in particular, comparable states of the vegetation sample.

Accordingly, a preferably invasive or, in other words, destructive examination method is proposed, in which vegetation components (e.g. leaves, stalks, fruits) are removed from the environment and pre-processed before the actual examination or measurement. It has been shown that this, in combination with the electrical examination method disclosed here, leads to particularly meaningful results.

According to preferred variants, the voltage applied is an AC voltage. A sample analysis can then be carried out by means of (for example dielectric or electrical) spectroscopy. In particular, a (dielectric) permittivity of the sample can be determined in an alternating field, preferably by varying an alternating current that generates the alternating field, i.e. by producing a frequency dependency. For example, the permittivity can be specified or quantified as a dielectric constant.

It has been shown that the permittivity enables meaningful conclusions to be drawn about the sample moisture that is still present. If the mass of the examined sample is known, a remaining dry mass fraction can be determined, which corresponds to the biomass, after deducting the sample moisture found (and more precisely the associated mass fraction).

The sample moisture can be determined, for example, as an absolute water mass, in particular to determine the biomass as an absolute value. A relative determination is also possible (i.e. a determination of the relative mass fraction of the sample moisture). In order to determine the remaining relative mass fraction of the biomass, this can be multiplied by the previously measured moist total mass and the absolute mass fraction of the biomass can be calculated.

A possibility for determining an impedance of the sample is also disclosed, preferably by applying a frequency-dependent AC voltage with electrically conductive contact between the sample and the electrode arrangement. In this case, too, a previously stored relationship between the impedance and the moisture content can be used to determine the sample moisture.

Mixed forms are also possible, in which the sample moisture is determined redundantly using both the permittivity and the impedance.

• - Komprimieren der Vegetationsprobe, so dass diese eine vorgegebene Form annimmt;
• - Anordnen der komprimierten Vegetationsprobe in einer Elektrodenanordnung und Anlegen einer Spannung an die Elektrodenanordnung;
• - Bestimmen wenigstens einer elektrischen Größe (z.B. der Probe, der Elektrodenanordnung und/oder eines damit verbundenen Stromkreises) wie, wenn die Spannung angelegt ist;
• - Bestimmen wenigstens einer (bevorzugt quantitativen) Eigenschaft der Vegetationsprobe auf Basis der elektrischen Größe.

In particular, a method for (preferably in situ and/or invasive or destructive) examination of a vegetation sample is proposed, with:

• - compressing the vegetation sample to have a predetermined shape;
• - placing the compressed vegetation sample in an electrode array and applying a voltage to the electrode array;
• - determining at least one electrical quantity (eg of the sample, the electrode arrangement and/or a circuit connected thereto) as when the voltage is applied;
• - Determining at least one (preferably quantitative) property of the vegetation sample on the basis of the electrical variable.

The compression therefore takes place before the sample is fed to or removed from the electrode arrangement. is examined with this. In particular, the vegetation sample is pressed and further preferably pressed into a defined shape. This variant is particularly effective after chopping, but can also be used without chopping. For example, by pressing, the sample can assume a cylindrical or pellet-like shape. In particular, it can thereby assume defined and repeatable (target) dimensions that enable high measurement accuracy. For example, a diameter (or generally at least one cross-sectional dimension) and/or a length of the sample can assume desired dimensions. These can be adapted to the corresponding dimensions of a recording space and/or the electrode arrangement, so that recordings can be made there, for example, without forming significant air gaps.

The compression can take place by means of a compression device, which can be included in and/or integrated in an examination arrangement disclosed herein. This can be operated manually. However, it preferably has an actuator system, for example a pneumatic or hydraulic pressure cylinder. In general, the compression device can be or comprise a hydraulic, spindle or vacuum press.

The compression thus in particular creates the possibility of producing a repeatable and/or standardized (desired) state of the sample and thus also of the general measurement conditions. This succeeds particularly reliably when, as is generally preferred, a standardized pressure is applied.

The electrical quantity can be, for example, an electrical quantity of an electric field generated by means of the electron arrangement and/or of a circuit feeding the electrode arrangement, or it can be derived from such quantities. In general, the electrical quantity can be measured directly. However, it can also be derived from other directly measured electrical variables, for example using characteristic curves, table values or calculation formulas. Preferred examples of the electrical quantity are given below.

As also explained below, the vegetation sample can be non-conductively connected to the electrical arrangement or, in other words, electrically isolated from it. In particular, an insulating material can be arranged between the electrode arrangement and the vegetation sample. This can have an insulating effect or, in other words, act as a dielectric to the extent that it suppresses current transmission to the sample, but allows the electric field to pass through with a certain minimum field strength. In this case, in particular a (dielectric) permittivity of the sample can be determined as an electrical quantity. This can be done, for example, by determining a current flow between electrodes of the electrode arrangement or within an electric circuit connecting the electrode arrangement to the voltage source.

In a manner known per se, a frequency variation of an applied AC voltage is advantageous for determining permittivity and also for determining impedance, which can also be provided accordingly within the scope of the invention.

Alternatively, the vegetation sample can be electrically connected to the electrode arrangement. A current flow can thus be generated through them, starting from the electrodes of the electrode arrangement. This is comparable to the provision of a non-insulating filling material between and in direct contact with the electrodes of a capacitor. In this case, too, an analog current measurement can take place, as discussed above. An impedance of the vegetation sample and preferably its frequency-dependent impedance can be determined as an electrical variable.

In the variant with additional insulating material, measurement influences due to direct interactions between the sample and, more precisely, its surface, with the electrode arrangement can be reduced.

In the variant without additional insulating material, generally more stable and/or stronger measurement signals can be generated, which makes the measurement less sensitive to interference. For example, the proportion of measurement noise in the measurement signals generated can turn out to be lower.

Depending on the accuracy and/or repeatability of the sample processing, the technical measuring accuracy (or also measuring ability) of the examination arrangement or an expected extent of the surface interaction of the vegetation sample, which can be plant-species-specific, for example, one of the above variants with or without additional insulating material can be preferred be.

In general, the electrode arrangement can comprise at least one cooperating pair of electrodes. The electrodes of the electrode pair can have a different polarity, for example by connecting to different poles of a voltage source. The sample can be placed between the electrodes. It can connect the electrodes in a conductive manner and/or be permeated by an electric field effective between the electrodes.

The property of the vegetation sample determined according to the method is preferably a non-electrical property, for example a plant-physiological, biological property and/or the vegetation and/or the state of vegetation.

A connection between the electrical variable and the property of the vegetation sample can be determined using stored comparison or, in other words, calibration data. The comparison data can preferably describe the relationship between the electrical variable and the sample property sought for a specific vegetation type (in particular a specific plant species), for example in the form of a collection of values, as a characteristic curve or as a functional relationship. A connection to a property of the sample can also be defined (e.g. its moisture content) on the basis of which the property actually sought is determined (e.g. the biomass).

The comparison data can be obtained with the same examination arrangement that is disclosed herein and/or with which the disclosed method is carried out. This can increase the comparability with later real measured values. Alternatively, the comparison data can be determined in a laboratory and/or by means of another examination arrangement in order to describe the connection as precisely as possible.

For example, a value of the electrical variable can be assigned to a corresponding value or a corresponding property within the comparison data, and the property of the vegetation sample can be determined based thereon.

In summary, one embodiment provides that the property of the vegetation sample is determined using previously stored data (herein also referred to as comparison or calibration data), the data describing a relationship between the electrical quantity and the (sought) property of the vegetation sample.

Optionally, a temperature dependency can also be taken into account. For this purpose, a sample temperature can generally be detected, preferably without contact. Any measured variables or properties can be calculated and/or adjusted as a function of this temperature. The comparative data can also be temperature-dependent in general. Preferably, at least the permittivity and/or sample moisture derived therefrom is determined as a function of temperature, e.g. using temperature-dependent comparison data or temperature-dependent correction factors.

All method steps described herein can be carried out using an examination arrangement which forms an integrated and/or a coherent assembly, in particular using an examination arrangement of the type disclosed herein. This examination arrangement is preferably manually portable and/or manually operable in order to carry out in-situ measurements .

The method may generally include a step of sampling from the environment and/or from nature. For this, vegetation samples (e.g. leaves) can be manually separated from individual plants or, albeit less preferably, whole plants can be taken from the subsoil. With an examination arrangement of the type disclosed here, vegetation samples can preferably be separated mechanically from the environment and fed to an actual measuring arrangement (or electrode arrangement).

The determined property of the vegetation sample is preferably sample moisture. As shown above, this can be converted into a relative mass fraction or a (remaining) absolute mass of the biomass. The comparison data mentioned can therefore define a relationship between the electrical variable and the sample moisture, with the biomass being able to be determined on the basis of the latter.

Likewise, the property of the vegetation sample can be its biomass. In this case, the comparison data can directly describe the relationship between the determined electrical variable and the biomass. This is possible in particular when a cylinder for separating vegetation and/or a sample receiving space of the device is filled with cuttings as completely as possible (e.g. based on a cylinder or space length) and/or when an above-ground part of vegetation is filled as completely as possible is removed. For example, the examination arrangement can reach down to the ground and, as cuttings, take up vegetation from its tip to the ground, separate it and press it. In this way, a biomass per cylinder area unit can be determined. For this purpose, the comparison data can also be defined in relation to a cylinder surface unit.

According to a preferred embodiment, the applied voltage is an alternating voltage and/or an electric field generated with the electrode arrangement is an alternating field. In this way, in particular, a dielectric permittivity of the sample can be determined, which allows meaningful conclusions to be drawn about its moisture content.

Accordingly, one embodiment provides that the electrical variable is an impedance or a permittivity of the vegetation sample.

A further embodiment provides that the voltage applied is a DC voltage and/or a DC field is generated. Combinations are also possible, for example a measurement process in which an alternating field and a constant field are generated in chronological succession and/or a corresponding voltage is applied (or vice versa).

By applying a DC voltage and/or generating a DC field, error variables can be determined that can falsify measurements based on an AC field or an AC current. For example, influences in the DC field resulting from electrophoresis processes can be determined and preferably quantified according to conventional approaches. Alternatively or additionally, electrical resistances of the sample can be measured for the same purpose and when the sample is in conductive contact with the electrode arrangement by applying a DC voltage. Subsequent measurements based on the alternating field and, in particular, values of the electrical variable determined in the process can be corrected on the basis of the quantified influences.

A development provides that the electric field is generated by means of an electrode arrangement. Depending on the desired field properties, the electrode arrangement (in particular a voltage source thereof) can be suitably controlled and/or energized.

According to embodiments below, it is possible to provide a plurality of pairs of electrodes. These can each be energized and/or connected to a voltage source in such a way that they each jointly generate an electrical (partial) field. In order to generate their respective electric fields, the pairs of electrodes can be driven or energized alternately in time or at least partially simultaneously.

As already mentioned, according to a preferred variant, the vegetation sample is taken from the (natural) environment and placed in situ in an examination arrangement.

Various variants for processing the sample are explained below. The processing can in each case be carried out with a correspondingly set up processing device of the examination arrangement.

A preferred embodiment provides that the vegetation sample is comminuted before it is compressed and/or exposed to the electric field. The comminution can take place mechanically and/or by machine, for example by means of movable cutting surfaces or a chopper. An examination arrangement for at least partial implementation of the method can be set up for such a comminution and in particular can include a corresponding comminution device.

The crushing homogenizes the sample, which improves the measurement accuracy, comparability and reproducibility of the measurement.

In this context, provision can be made for the vegetation sample to be weighed before and after the comminution in order to determine a mass loss. Any weighing operations mentioned herein may be performed with a scale included in an assay assembly disclosed herein. Alternatively, the weighing can be carried out using separate scales and the sample can only be supplied to the examination arrangement in a subsequent step.

By determining the loss of mass, it can be determined, for example, whether an excessively high proportion of the vegetation sample was lost during the shredding (e.g. by sticking inside a shredder or the like). In this way it can be ensured that the sample still has a desired representative state.

As a further possible processing, the sample can be dried, for example by means of a heating device of a type disclosed herein. The heating device can in turn be included in an examination arrangement of the type disclosed herein. For the purpose of drying, the sample can be heated to at least 50° C. and preferably at least 60° C., however, it can be heated to a maximum of 105° C. Drying can serve to create comparable measurement conditions, e.g. be part of a standardized measurement process. A loss of moisture that occurs here can also be recorded as a loss of mass. This can be taken into account when the sample moisture is determined in the manner described above. However, it can also be provided that only the moisture loss as a result of the above processing is determined and taken into account, e.g. if several samples are dried in a comparable, standardized manner.

Provision can also be made for the vegetation sample to be weighed after it has been compressed. This allows the (wet) total mass to be determined. As shown above, a determined wet mass fraction can be subtracted from this, for example, in order to determine the biomass of the sample.

• - einer Komprimierungseinrichtung zum Komprimieren der Vegetationsprobe, sodass diese eine vorgegebene Form annimmt;
• - einem Aufnahmeraum zur Aufnahme der komprimierten Vegetationsprobe;
• - einer Elektrodenanordnung, die den Aufnahmeraum zumindest abschnittsweise umgibt;
• - einer Analyseeinrichtung, die dazu eingerichtet ist, wenigstens eine elektrische Größe zu ermitteln, wenn eine Spannung an die Elektrodenanordnung bei in dem Aufnahmeraum aufgenommener Vegetationsprobe angelegt wird, und die ferner dazu eingerichtet ist, wenigstens eine Eigenschaft der Vegetationsprobe auf Basis der elektrischen Größe zu ermitteln.

The invention also relates to an examination arrangement for in-situ examination of a vegetation sample, with:

• - a compression device for compressing the vegetation sample so that it assumes a predetermined shape;
• - a receiving space for receiving the compressed vegetation sample;
• - An electrode arrangement which surrounds the receiving space at least in sections;
• - An analysis device which is set up to determine at least one electrical variable when a voltage is applied to the electrode arrangement when the vegetation sample is received in the receiving space, and which is also set up to determine at least one property of the vegetation sample on the basis of the electrical variable .

All of the above components, but also any other component of the examination arrangement mentioned herein, but preferably at least the receiving space and the electrode arrangement, can be part of a structurally combined and/or integrated unit. It is therefore also possible to first process and in particular compress the sample using a first unit of the examination arrangement and then to introduce the compressed sample into a second and structurally separate unit of the examination arrangement, which includes the receiving space and the electrode arrangement. As a result, the handling of the examination arrangement can be improved since, for example, a respective size and a respective weight of the units can be reduced compared to a fully integrated assembly (also included in the disclosure) which includes both units.

According to a preferred variant, the examination arrangement comprises a position-determining device with which position information of the device (and in particular when a sample is taken with it) can be determined. The position determination device can, for example, comprise a GPS or GNSS sensor or some other sensor for satellite-based position determination. The position information may include position coordinates. The position information can be assigned to measurement data obtained (e.g. in the form of determined sample properties) and/or stored together with them.

The receiving space can be cylindrical and/or hollow-chamber-like. It may extend along a longitudinal axis and be generally elongate. Preferably, the receiving space is an upright (hollow) cylinder with a circular cross-sectional shape. This is advantageous for recording samples that have been pressed into pellets, for example. This also enables the electrode arrangement to have a less complex structure, with which high measurement accuracy can be achieved. The sample can be introduced into and/or removed from the recording space along the longitudinal axis (e.g. manually or mechanically).

Accordingly, the receiving space can be tubular or be surrounded by a tubular part of the examination arrangement. This part can also be called the sample tube.

The analysis device can include at least one programmable computing unit. It can include a memory device on which the (digital) comparison data disclosed herein can be stored. It can comprise at least one measuring device or be connected to one, by means of which the electrical variable can be measured or from the measurements of which the electrical variable can be derived.

According to a development, the electrode arrangement extends at least in sections along the receiving space and/or encloses it at least in sections. In particular, the electrode arrangement or an intermediate wall of the type below can at least partially form a side wall of the receiving space and/or delimit the receiving space at least in sections (in particular in the radial direction).

One embodiment provides that the electrode arrangement can be brought into at least partial contact with the vegetation sample.

Alternatively, it can be separated from the vegetation sample at least in sections by means of a non-conductive partition. The intermediate wall is preferably a dielectric or, to put it another way, slightly electrically conductive or insulating. In this way, the permittivity of the sample and, based thereon, preferably its moisture content, can be determined, in particular when a frequency-variable AC voltage is preferably applied.

The electrode arrangement can have at least one and preferably a plurality of electrode pairs. In other words, the electrode arrangement can be segmented into a corresponding plurality of electrode pairs. The segmentation can be axial or radial in relation to a longitudinal axis of the receiving space. In other words, the individual electrodes of a pair can extend along a longitudinal axis of the receiving space arranged sequentially or, in the case of radial segmentation, distributed in a circumferential direction around the receiving space.

In the case of axial segmentation, field lines or a current flow between the individual electrodes can run axially at least in sections (or generally primarily). In the case of a radial segmentation, in which the individual electrodes can preferably lie radially opposite one another, field lines or a current flow between the individual electrodes can run radially at least in sections (or generally primarily).

As mentioned above, the pairs of electrodes can each generate an electric field together. A value of the electrical variable can also be determined by means of each of the pairs of electrodes (e.g. by measuring a respective current flow at or between the electrodes). The values obtained in total can be offset against a final value of the electrical variable, in particular by averaging.

It has been shown that, particularly in the case of heterogeneous samples, more accurate measurement results can be achieved by means of segmentation. In this way, highly heterogeneous areas can, for example, significantly influence the measurement result of at least one pair of electrodes. This can be recognized separately (e.g. as a threshold value being exceeded and/or using statistical analysis methods and/or mathematical outlier recognition in comparison to measurement results from other pairs of electrodes). Based on this, a calculation can be adjusted (e.g. by lower weighting of this measurement result) or the measurement can be recognized as faulty. In summary, local sample heterogeneity, e.g. B. be recognized as measurement result outliers and based on this, e.g. a (possibly missing) quality of the sample can be concluded.

Even without such adjustment of the calculation and e.g. with conventional averaging of all measurement results, the probability increases that the heterogeneous area will be included in the measurement result to an appropriate extent and the measurement result will be more representative. This applies in particular in comparison to measuring with only one pair of electrodes, in which the influence of only local heterogeneity cannot usually be recorded in a comparable representative manner.

According to a preferred embodiment, the receiving space is hollow-cylindrical and/or tubular. The electrode arrangement is preferably shaped to correspond to at least sections of the receiving space. It is therefore preferably likewise hollow-cylindrical, tubular and/or curved, at least in sections. For example, the electrode arrangement can be part of a curved outer surface of the receiving space or be curved in a manner corresponding to this outer surface. It can enclose the receiving space in the form of a tube, but optionally does not necessarily have a closed surface (i.e. it does not form a closed tube) due to the following segment-like subdivision.

• 1 zeigt eine schematisch stark vereinfachte Ansicht einer Untersuchungsanordnung gemäß einem Ausführungsbeispiel, mit der ein erfindungsgemäßes Verfahren gemäß einem Ausführungsbeispiel durchführbar ist.
• 1a zeigt eine Unteransicht der Untersuchungsanordnung aus 1;
• 2 zeigt ein Ablaufschema eines möglichen Verfahrens gemäß einem Ausführungsbeispiel;
• 3-9 zeigen Ausgestaltungen einer Elektrodenanordnung der Untersuchungsanordnung aus 1 gemäß verschiedenen Ausführungsbeispielen;
• 10a-f zeigen eine Messabfolge mit einer stark vereinfacht abgebildeten Untersuchungsanordnung gemäß einem weiteren Ausführungsbeispiel.

Exemplary embodiments of the invention are explained below with reference to the accompanying schematic figures.

• 1 shows a schematically greatly simplified view of an examination arrangement according to an embodiment, with which a method according to the invention can be carried out according to an embodiment.
• 1a shows a bottom view of the examination arrangement 1 ;
• 2 shows a flow chart of a possible method according to an embodiment;
• 3-9 show configurations of an electrode arrangement of the examination arrangement 1 according to various embodiments;
• 10a-f 12 show a measurement sequence with an examination arrangement shown in a highly simplified manner according to a further exemplary embodiment.

In 1 a schematically highly simplified view of an examination arrangement 10 according to an exemplary embodiment is shown. In the state shown, the inspection arrangement 10 takes a vegetation sample from the environment. To put it more precisely, the examination arrangement 10 is preferably placed manually on a part of a vegetation area 12 or, in other words, placed over it, with individual vegetation parts (for example individual plants or individual plant components) entering the examination arrangement 10 . 1 shows a corresponding movement arrow B of the examination arrangement 10 for vegetation sampling.

The proportions in 1 are not representative. In the case shown, it can be seen that the examination arrangement 10 is surrounded by at least parts of the vegetation, that is, for example, it is inserted in the middle of a vegetation field or vegetation bed.

The examination arrangement 10 comprises a cylindrical part 14, also known as a probe tube or sample receiving tube. The cylindrical part 14 has a longitudinal axis L and a preferably circular cross section.

In the range of one in 1 Underside of the cylindrical part 14, the in 1a cutting device 16 shown may be provided. By way of example only, the cutting device 16 is provided with a plurality of mechanical cutters, which can reduce a radial distance from one another, in particular as a result of a rotary movement D, in the manner of an objective diaphragm. A free space 18 remaining between the cutting edges, into which parts of vegetation get, can thereby be successively reduced in order to separate the parts of vegetation.

coming back on 1 , the dashed detail A shows a schematically highly simplified exemplary internal structure of the cylindrical part 14 or of the components included therein. The cutting device 16 is again shown at a lower end. According to the arrow shown and, for example, as a result of a manual tilting of the examination arrangement 10, the separated vegetation sample can reach a weighing chamber 20. A housing surface 22 with an integrated weighing device is initially closed. As a result of the tilting, the vegetation sample rests on this housing surface 22 and can be weighed.

For example, by mechanically or electrically (actuating) opening of the bottom surface 22, the vegetation sample (sample) that has been taken reaches a comminuting device 24. This is, for example, a shredder or a mill.

After the sample has been crushed and, for example, after a housing surface 26 of the crushing device 24 has been opened again (including tilting of the examination arrangement 10), the vegetation sample reaches a compression device 30. Optionally, it can pass through a heating device 28 and there, for example, heated for a defined minimum time and thereby dried will. As a result, a water content can be reduced, which improves the compression and measurement quality.

The heating device 28 can also be integrated into the compression device 30 . Additionally or alternatively, a weighing device can be integrated into the compression device 30, in particular to determine the weight of a pellet produced. This weight can correspond to the wet mass of the sample that is subsequently measured.

In the compression device 30, the sample is compressed into a preferably cylindrical pellet with a circular diameter. From there, it reaches a receiving space 32 (alternatively: examination space), which is surrounded by an electrode arrangement 34, for example by means of similar opening housing surfaces as explained above. By means of the electrode arrangement 34, an electric field is generated in the manner described below or an electric current is applied to the sample and an electric variable is determined in order to infer the sought-after properties of the sample.

Measurement signals from the electrode arrangement 34 (in particular from an ammeter connected thereto, not shown, or another electrical measuring device) are output to an analysis device 36 . The measurement signals can also be tapped off at a supply circuit of the electrode arrangement 34, in particular in order to determine the currents that are set when a sample is present. This uses the measurement signals to determine a value for the electrical quantity sought, in particular the permittivity of the sample. For this purpose, a measurement in the manner of (di)electric spectroscopy can be carried out by varying the frequency of an alternating field that is generated.

By means of comparison data from a memory device (not shown separately), values of a sought-after property of the sample can be assigned to the electrical quantity. By way of example, this property can be a moisture content and can be inferred therefrom based on the biomass as the remaining fraction of the previously measured sample weight. The value of the biomass can be displayed using a display device that is not shown separately.

In principle, preferably with the exception of the electrode arrangement 34, the receiving space 32 and the analysis device 36, any of the mentioned devices 28, 30, 26, 20, 16 can also be provided outside or separately from the examination arrangement 10 shown. For example, they can be included in a sample preparation unit, not shown, in which the vegetation sample taken is weighed in the manner described and preferably processed into a pellet. The pellet can then be removed manually from the sample preparation unit and fed to a measuring unit of the examination arrangement 10 and, more precisely, to its receiving space 32 .

In 2 an exemplary process flow is shown, as it is with the examination arrangement out 1 is feasible. In a step S1, a vegetation sample is taken from the surroundings.

The sample is weighed in step S2 and then crushed in step S3. After the comminution, another weighing takes place in step S4 and the weights determined in steps S2 and S4 are compared in the subsequent step S5. If the weights deviate to an inadmissibly high extent, the sample can be assessed as unsuitable and a new sample can be taken.

In an optional step S6, the crushed sample is heated to reduce its moisture content. Subsequently, in step S7, the sample is compressed or, more precisely, pressed into shape. In this way, the homogenized, because it is crushed and preferably also dried, sample mass assumes a defined shape with preferred dimensions (in particular a cylindrical shape with a predetermined diameter).

In step S8, the pressed sample is weighed again in order to determine its (moist) total mass.

In step S9, the sample is arranged within the electrode arrangement 34 to which an AC voltage, preferably with a variable frequency, is applied. Based on a monitored current flow to and/or between the electrodes, the impedance or the permittivity of the sample is determined as the sought-after electrical variable by means of common impedance or permittivity determination.

In step S10, the desired property of the sample is assigned to the determined electrical variable using previously stored comparison data. In the present case, this property is the remaining biomass (i.e. the dry portion of the wet total mass from step S8).

Based on the below 3-9 various electrode arrangements 34 are discussed, as they are in the examination arrangement 10 from 1 can be used as an example.

In 3 one recognizes first again a section of the cylindrical part 14 of the examination arrangement 10. This is generally hollow. The electrode arrangement 34 extends as a hollow cylinder (segmented in the manner described below) along an inner wall of the cylindrical part 14 and along its longitudinal axis L. The electrode arrangement 34 preferably comprises three individual electrodes 33, each of which is tubular with a closed circumference and is formed along the longitudinal axis L are lined up. In other words, the electrode arrangement 34 is axially segmented and, to put it more precisely, divided into the preferably three individual electrodes 33 which follow one another in the axial direction.

Also shown is an electrically insulating intermediate wall 40. This is designed, for example, as a continuous tube that extends along the inner walls of the individual electrodes 33 and the longitudinal axis L. FIG. The intermediate wall 40 (or generally the electrode assembly 34) surrounds an elongated cylindrical cavity which forms the receiving space 32. A sample 42 compressed into a cylindrical pellet is shown in the receiving space 32 by way of example. The intermediate wall 40 also has radially protruding sections 41, by means of which the individual electrodes 33 are electrically insulated from one another. Alternatively, the sections 41 can be formed separately from the intermediate wall 40 and can be used, for example, as rings between the individual electrodes 33 .

It can be seen that the sample 42 rests against the intermediate wall 40 and its dimensions and in particular the diameter are consequently adapted to the dimensions and in particular the diameter of the receiving space 32 . This improves repeatability and limits electrical error effects due to air gaps between the sample 42 and the partition 40, for example.

An AC voltage is applied to the individual electrodes 33 in such a way that the polarity of the central individual electrode 33 differs from that of the two axially outer individual electrodes 33 in each case. This results in two pairs of interacting individual electrodes 33, with the central individual electrode 33 being a component of both pairs. A primarily axial course of field lines within the pairs (i.e. from the central individual electrode 33 to one of the outer individual electrodes 33) is indicated.

Due to the electrically insulating property of the intermediate wall 40, there is no direct current transfer from the electrode arrangement 34 to the sample 42. It is therefore possible in this case to determine the permittivity of the sample 42, preferably by means of dielectric spectroscopy by measuring currents feeding the electrode arrangement 34.

In 4 is in this respect an analogous structure of the electrode arrangement 34 to the variant 3 shown when again an intermediate wall 40 is provided. In this case, however, the individual electrodes 33 are arranged differently, so that different interacting electrode pairs are also formed. In addition to the already based on 3 For the axial segmentation explained above (including electrical insulation via the sections 41), radially segmented individual electrodes 33 are provided for each axial section. In other words, in this case the individual electrodes 33 are designed as half-shells (or also half-shell-shaped cylinder jacket segments), which each form half the circumference of a tube. This radial segmentation corresponds to that from the one below 7 .

For each axial section, with the axial sections being electrically isolated from one another via the insulating sections 41, there are thus two radially opposite individual electrodes 33 which form a cooperating pair. As indicated by field lines, a radially propagating electric field that penetrates the sample 42 can be generated by applying a voltage with opposite polarity to the individual electrodes 33 of a respective pair.

Both in the variant from 3 as well as the variant 4 individual measurement results can be achieved with each interacting pair of individual electrodes 33, for example permittivity values determined herewith. These individual values can then be averaged, for example. The large number of individual measurements reduces the risk that the result will be influenced excessively, for example by a locally limited inhomogeneity in the sample 42 .

In general, the number of interacting pairs of electrodes in the figures is only exemplary. It can also be provided that there is only one pair of electrodes, for example in 3 only the upper two axially consecutive electrodes 33 or in 4 the two upper radially segmented electrodes 33.

Furthermore, a voltage can be applied to the individual electrodes 33 of all interacting pairs simultaneously (to all pairs) or sequentially (all pairs sequentially). In general, any groups of simultaneously and non-simultaneously live electrode pairs can be formed. By applying a voltage one after the other in time, influences on the measurement results and/or the electric fields of the pairs can be limited. However, compared to the simultaneous application of a voltage, the measuring time can increase.

In 6 is one to 4 analog design shown and in 7 an analog design 5 . The analogy consists in particular in the axial and/or radial segmentation of the electrode arrangement 32 and the structure of the respective individual electrodes 33. Axial intermediate sections 41 are also present in order to carry out the radial segmentation. However, the intermediate wall 40 is omitted in each case. The sample 42 is consequently in electrically conductive contact with the electrode arrangement 34.

If an alternating voltage is preferably applied to the electrode arrangement 34 and, in particular, its frequency is varied, the frequency-dependent impedance of the sample 42 can be determined as an electrical variable. Again, for this purpose, all interacting individual electrode pairs can be energized simultaneously or sequentially.

In 7 Figure 12 is a plan view along the longitudinal axis L of the variant 6 shown. One can see the radial segmentation of the individual electrodes 33 and their electrical insulation from one another by means of the sections 41.

In 8th shows that smaller radial segmentations are also possible. In the example there (the visual axis corresponds to that from 7 ) Four individual electrodes 33 are shown, each corresponding to a quarter part of a tube and in particular to a quarter of a tube cross-section. In each case two of the individual electrodes 33 act together as a pair in such a way that a current is applied to them at the same time (or different voltage poles are applied). Preferably, the two pairs are operated alternately or sequentially. In this way, the number of individual measurement results can be increased with a compact size.

In 9 a smaller radial segmentation is shown with eight individual electrodes 33. Two radially opposite individual electrodes can be used analogously to 8th form a cooperative pair.

In principle, it is also possible to provide at least one electrode arrangement 34 that is electrically insulated from the sample 42 and at least one electrode arrangement that is electrically conductively connected to the sample 42, or at least one corresponding pair of electrodes. Then both the permittivity and the impedance of the sample 42 can be determined with one setup in order to determine the desired sample property even more precisely using different measuring principles.

In 10a-f an examination arrangement 10 according to an alternative exemplary embodiment and in different measurement phases is shown. The examination arrangement 10 can preferably be held and operated manually. In each of the 10a-f a side view is shown in an upper part and in the lower part a plan view. The different viewing angles become clearer from the respective position of a longitudinal axis L. Not all components of the examination arrangement 10 are shown in the side layers, but usually only one removal part 100.

As can be seen from the bottom plan view of e.g 10a As illustrated, the preferably cylindrical removal part 100 is arranged on a carrier 102 . An examination part 104 is also arranged on the carrier 102 . This is initially at an angular distance from the removal part 100. However, the removal part 100 and the examination part 104 can be pivoted relative to one another, preferably around the carrier 102. An example only in FIG 10a pivot axis R shown is perpendicular to the plane of the page. As a result, the removal part 100 can initially be essentially free-standing and enable simple removal of vegetation. As explained below, however, it can then be selectively brought into overlap with the examination part 104 in order to transfer a vegetation sample 42 to it.

A vegetation sample 42 can be removed and preprocessed, in particular pressed and shaped, with the removal part 100 of the examination arrangement 10 .

The sample 42 can then be transferred to the examination part 104 and examined there in the manner described above. For this purpose, the examination part 104 comprises the receiving space 32 and the electrode arrangement 34 and preferably also the analysis unit 36 or is connected or can be connected to the latter.

In 10a shows how the removal part 100 is guided into an area with vegetation (see movement arrow there). As shown in the partially cutaway condition of 10b As can be seen, part of the vegetation then enters the removal part 100. To separate this vegetation, the removal part 100 preferably comprises a cutting device 16, as described above 1 explained.

As a preferred variant, it is shown that the cutting device 16 is arranged in a telescopically advanceable part 108 of the removal part 100 . By sliding this part 108 in and out, the cutting device 16 can be opened and closed, preferably automatically, in order to cut off the introduced part of the vegetation.

According to 10c the extraction part 100 with the vegetation that has been separated and accommodated therein can be lifted off the vegetation area. The recorded vegetation is by any of the to 1 The devices 20, 24, 28, 30 explained can be processed into a sample 42 with the desired shape and desired condition, with all the devices 20, 24, 28, 30 preferably being encompassed by the removal part 100.

In the top view of 10d is shown that the removal part 100 is positioned below the examination part 104, namely by pivoting about the axis R of the carrier 102. Former positions of the removal part 100 are in the 10d-f generally indicated by dashed lines.

In this state or even before that, the removal part 100 (or alternatively the entire examination arrangement 10) can also be tilted about a horizontal axis and is positioned upside down. As in 10e Thus, as shown, telescoping portion 108 is positioned on top of and opposite examination portion 104. By advancing telescoping portion 108, compressed sample 42 may be transferred to or introduced into examination portion 104. FIG. An (electrical) examination of the sample 42 then takes place in the examination part 104 by means of any of the variants described herein.

According to 10f the examination arrangement 10 is finally returned to its initial state and for this purpose the removal part 100 is pivoted again relative to the examination part 104 and arranged at a distance relative thereto. For reasons of clarity, the plan view is off 10f the examination part 104 is not shown again separately.

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102007058836 A [0005]

Claims (11)

A method of examining a vegetation sample (42), comprising: - compressing the vegetation sample (42) to assume a predetermined shape; - placing the compressed vegetation sample (42) in an electrode assembly (34) and applying a voltage to the electrode assembly (34); - determining at least one electrical quantity when the voltage is applied; - Determining at least one property of the vegetation sample (42) on the basis of the electrical quantity. procedure after claim 1 , characterized in that the property of the vegetation sample (42) is one of: - a sample moisture; - a biomass of the vegetation sample (42). procedure after claim 1 or 2 , characterized in that the voltage is an AC voltage. procedure after claim 3 , characterized in that the electrical variable is a permittivity or an impedance of the vegetation sample (42). procedure after claim 1 or 2 , characterized in that the voltage is a DC voltage. Method according to one of the preceding claims, characterized in that the vegetation sample (42) is processed according to at least one of the following variants: - the vegetation sample (42) is crushed before compression; - the vegetation sample (42) is weighed to determine a mass loss before and after crushing; - the vegetation sample (42) is weighed after compression; - the vegetation sample (42) is heated for drying. Examination arrangement (10) for examining a vegetation sample (42), with: - a compression device (30) for compressing the vegetation sample (42) so that it assumes a predetermined shape; - a receiving space (32) for receiving the compressed vegetation sample (42); - An electrode arrangement (34) which surrounds the receiving space (32) at least in sections; - an analysis device (36) which is set up to determine at least one electrical variable when a voltage is applied to the electrode arrangement (34) when the vegetation sample (42) is received in the receiving space (32), and which is also set up to do this, to determine at least one property of the vegetation sample (42) on the basis of the electrical variable. Investigation arrangement (10) after claim 7 , characterized in that the electrode arrangement (34) is separated from the vegetation sample (34) at least in sections by means of a non-conductive partition (40). Investigation arrangement (10) after claim 7 or 8th , characterized in that the electrode arrangement (34) can be brought into contact with the vegetation sample (42) at least in sections. Investigation arrangement (10) according to one of Claims 7 until 9 , characterized in that the electrode arrangement (34) has a plurality of interacting pairs of electrodes, the individual electrodes (33) of at least one pair of electrodes being arranged in succession along a longitudinal axis (L) of the receiving space (32) and/or in a circumferential direction around the receiving space ( 32) are distributed. Investigation arrangement according to one of Claims 7 until 10 , wherein the receiving space (32) is hollow-cylindrical and/or tubular and wherein the electrode arrangement (34) is shaped correspondingly to at least sections of the receiving space (32).

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