阅读说明：本技术 填充水平测量设备 (Fill level measuring device ) 是由 弗洛里安·法尔格 弗洛里安·帕拉蒂尼 彼得·克勒费尔 德特勒夫·施莱弗布克 于 2019-01-14 设计创作，主要内容包括：本发明涉及一种用于确定容器(2)中的填充材料(3)的填充水平(L<Sub>R</Sub>)的填充水平测量设备。该设备包括：雷达模块(11),该雷达模块用于在填充材料(3)的方向上发射雷达信号(S<Sub>R</Sub>),并且用于根据所反射的雷达信号(S<Sub>R</Sub>)确定距填充材料(3)表面的距离(D<Sub>R</Sub>)；3D相机(12),该3D相机用于捕获(R<Sub>3D</Sub>)填充材料(3)表面的至少一个区域([m；n])；以及评估电路(13),所述评估电路被设计成根据所捕获的(R<Sub>3D</Sub>)的距离值(d<Sub>i,j</Sub>)测量最大距离值(d<Sub>max</Sub>)和最小距离值(d<Sub>min</Sub>),并且若距离(D<Sub>R</Sub>)小于最大距离值(d<Sub>max</Sub>)且大于最小距离值(d<Sub>min</Sub>),则基于距离(D<Sub>R</Sub>)确定填充水平(L<Sub>R</Sub>)。由于由3D相机提供的雷达模块(11)计算出的距离(D<Sub>R</Sub>)的冗余或验证,因此,根据本发明的填充水平测量设备(1)在错误计算不正确的填充水平(L)方面变得更加可靠。(The invention relates to a method for determining a filling level (L) of a filling material (3) in a container (2) R ) The fill level measuring device of (1). The apparatus comprises: a radar module (11) for emitting a radar signal (S) in the direction of the filling material (3) R ) And for deriving from the reflected radar signal (S) R ) Determining the distance (D) to the surface of the filling material (3) R ) (ii) a A 3D camera (12) for capturing (R) 3D ) At least of the surface of the filling material (3)A region ([ m; n)]) (ii) a And an evaluation circuit (13) designed to evaluate the captured (R) 3D ) Distance value (d) of i，j ) Measuring the maximum distance value (d) max ) And a minimum distance value (d) min ) And if the distance (D) R ) Less than the maximum distance value (d) max ) And is greater than the minimum distance value (d) min ) Then based on distance (D) R ) Determining a fill level (L) R ). Due to the distance (D) calculated by the radar module (11) provided by the 3D camera R ) Thereby, the filling level measuring device (1) according to the invention becomes more reliable in miscalculating incorrect filling levels (L).)

1. A method for determining a filling level L of a filling material (3) located in a container (2)_RThe system of (1), comprising:

-a radar module (11) designed to emit a radar signal (S) in the direction of the filling material (3)_R) And based on the reflected radar signal (S)_R) Determining the distance (D) to the surface of the filling material (3)_R)，

-a 3D camera (12), said 3D camera being designed to be based on at least one region ([ m; n) of said surface of said filling material (3)]) Record (R) of_3D) According to said region ([ m; n is]) Corresponding position within ([ i, j)]) To determine a plurality of distance values (d)_i，j) And an

-an evaluation circuit (13) configured to:

o according to the distance value (d)_i，j) Determining a maximum distance value (d)_max) And a minimum distance value (d)_min) (ii) a And

omicron if said distance (D)_R) Less than said maximum distance value (d)_max) And said value greater than the minimum distance value (d)_min) Using said distance (D)_R) Determine what isThe filling level (L)_R)。

2. Fill level measuring device according to claim 1, wherein the evaluation circuit (13) is configured to evaluate the distance (D) if determined by the radar module_R) Less than the minimum distance value (d)_min) Or greater than said maximum distance value (d)_max) Then outputs a first warning signal(s)_f1)。

3. Fill level measuring device according to claim 1 or 2, wherein the evaluation circuit (13) is configured to evaluate the minimum distance value (d) if it is the minimum distance value (d)_min) Less than a predefined maximum level (L)_max) Is detected, the first warning signal(s) is output_f1) And/or another warning signal(s)_fn)。

4. Fill level measuring device according to one of the preceding claims, wherein the evaluation circuit (13) is configured to:

-by deriving from said maximum distance value (d)_max) Minus the minimum distance value (d)_min) To calculate a difference (Δ d), an

-if said difference (Δ d) exceeds a predefined maximum range (Δ d)_max) Outputting said first warning signal(s)_f1) And/or another warning signal(s)_fn)。

5. Fill level measuring device according to any one of the preceding claims, wherein the evaluation circuit (13) is designed to evaluate the record (R)_3D) The region of ([ m; n is]Of the selected portion of (a) to (d)_i，j) -determining scattering, and wherein the evaluation circuit (13) determines the roughness of the surface of the filling material (3) from the determined scattering.

6. Fill level measuring device according to any one of the preceding claims, wherein the radar module (12) is designed such thatTransmitting said radar signal at 75GHz less frequencies (S)_HF)。

7. Filling level measuring device according to any one of the preceding claims, wherein the radar module (12) is designed to determine the distance (D) to the surface of the filling material (3) by means of an FMCW method or by means of a pulse propagation method_R)。

8. Fill level measuring device according to any one of the preceding claims, wherein the 3D camera (12) is designed to generate the region ([ m; n)]) Of the filling material (3), in the region ([ m; n is]) The 3D camera (12) determines the distance value (D)_i，j)。

9. Fill level measuring device according to any one of the preceding claims, wherein the evaluation circuit (13) is designed to evaluate the distance values (d) on both sides of the contour if the distance values (d) on both sides of the contour are detected along the contour_i，j) The discontinuity between, then is based on the region ([ m; n is]) Said record (R) of_3D) To detect the contour.

10. Fill level measuring device according to claim 9, wherein the evaluation circuit (13) is designed to detect a movement and/or a displacement of the contour.

11. Fill level measuring device according to claim 9 or 10, wherein the evaluation circuit (13) is designed to determine an internal cross section, in particular an internal cross-sectional area, of the container (2) on the basis of the detected contour.

12. Filling level measuring device according to at least one of the preceding claims, wherein the evaluation circuit (13) is designed such that it can be based on the region ([ m; n)]) Said record (R) of_3D) Determining an approximately flat plane, determining the filling level measuring deviceRelative to the vertical orientation.

13. Determination of a filling level (L) of a filling material (3) located in a container (2) by means of a filling level measuring device (1) according to any one of the preceding claims_R) The method of (1), comprising the method steps of:

-based on reflected radar signals (S) emitted by a radar module (11) in the direction of the filling material (3)_R) Determining a distance (D) to the surface of the filling material (3)_R)，

-at least one region ([ m; n) based on the surface of the filling material (3)]) Recording (R) of the 3D camera (12)_3D) To ascertain a plurality of distance values (d)_i，j)，

-depending on the distance value (d) by means of the evaluation circuit (13)_i，j) Determining a maximum distance value (d)_max) And a minimum distance value (d)_min)，

-if said distance (D) is not sufficient_R) Less than said maximum distance value (d)_max) And is greater than the minimum distance value (d)_min) By means of the distance (D) from the evaluation unit (13)_R) Determining the filling level (L)_R)。

Technical Field

The invention relates to a radar-based fill level measuring device.

Background

Field devices for capturing and/or modifying process variables are often used in process automation technology. For detecting process variables, sensors are used, for example, sensors used in filling level measuring devices, flow measuring devices, pressure and temperature measuring devices, pH redox potential measuring devices, conductivity measuring devices, etc. They detect the corresponding process variables, such as fill level, flow, pressure, temperature, pH, redox potential or conductivity. Various such field devices are manufactured and sold by Endress + Hauser corporation.

In order to measure the filling level of the filling material in the container, non-contact measuring methods have been established, as they are robust and require minimal maintenance. Within the scope of the present invention, the term "vessel" also refers to an unsealed vessel, such as a pool, lake or flowing body of water. Another advantage of the non-contact measurement method is the ability to measure the fill level quasi-continuously. Thus, radar-based measurement methods are mainly used in the field of continuous fill level measurement (in the context of the present patent application, "radar" is defined as a signal or electromagnetic wave with a frequency between 0.03GHz and 300 GHz). Here, two common measurement principles are the pulse propagation principle (also referred to as "pulse radar") and the FMCW principle ("frequency modulated continuous wave").

A fill level measuring device operated by the pulse propagation method is described, for example, in the unexamined patent application DE 102012104858a 1. For a typical construction of an FMCW-based fill-level measuring device, reference is made by way of example to the unexamined patent application DE102013108490a 1. Radar-based fill level measurements are very accurate and insensitive to rough or wrinkled fill material surfaces. However, depending on the type of filling material and the properties of the interior of the container, it may not always be possible to verify the filling level value determined by the radar, since, for example, in some cases, unwanted echoes are used incorrectly for filling level calculations, rather than echoes of the filling material surface. This may lead to an erroneous determination of the filling level, as a result of which in some cases a corresponding dangerous situation may occur in the process plant.

Disclosure of Invention

It is therefore an object of the present invention to provide a safer filling level measuring device.

The invention achieves this object by means of a filling level measuring device for determining a filling level of a filling material located in a container, the device comprising:

a radar module designed to emit radar signals in the direction of the filling material and to determine the distance to the surface of the filling material based on the reflected radar signals,

-a 3D camera designed to determine a plurality of distance values from respective positions within a region based on a recording of at least one region of the surface of the filling material, an

-an evaluation circuit configured to:

calculating a maximum distance value and a minimum distance value from the distance values, and

if the distance is less than the maximum distance value and greater than the minimum distance value, the fill level is determined based on the distance.

Within the framework of the present application, the term "3D camera" includes any system by means of which individual distance values of the closest object can be recorded as corresponding pixel values in a selected image area. Thus, for example, a so-called TOF camera ("time of flight") can be used for this purpose, which TOF camera comprises a corresponding semiconductor-based sensor (also referred to as PMD sensor, "photon mixing device"). However, the same functionality can also be realized, for example, by means of a so-called light field camera or at least two conventional digital cameras connected to each other.

Due to the redundancy or verification of the measured values determined by the radar module by means of the 3D camera, the filling level measuring device of the invention becomes more secure in determining the correct filling level. However, the radar module can still ensure high measurement accuracy. The measurement accuracy of the radar module increases with increasing radar signal frequency. It is therefore advantageous to design the radar module to transmit radar signals at a frequency of at least 75GHz (whether the radar module determines the distance to the surface of the filling material by the FMCW method or by the pulse propagation method). It goes without saying that the invention can also be implemented at lower frequencies, for example 26 GHz.

In the event of an error, that is to say if the distance determined by the radar module is less than a minimum distance value or greater than a maximum distance value, the evaluation circuit can be designed, for example, such that it outputs a first warning signal in this case. This may be transmitted to the control center via a corresponding interface of the field device so that a reaction may be performed in the process plant or the fill level measuring device may be checked by a service technician.

The evaluation circuit may also be designed to output the first warning signal and/or the further warning signal if the minimum distance value is smaller than the respective value of the predefined maximum filling level. This corresponds to at least the point-like shape exceeding the filling level beyond the maximum allowed filling level. It is advantageous here that a punctiform exceeding of the maximum filling level has already been detected, even if the radar module has not yet detected this (for example due to a bulk material cone during filling).

In a further design variant of the fill-level measuring device, the evaluation circuit can be designed as

-calculating a difference value by subtracting the minimum distance value from the maximum distance value, and

-outputting the first warning signal and/or the further warning signal if the difference exceeds a predefined maximum range.

In this case, a warning signal is output as soon as the surface of the filling material becomes too uneven or the distribution of the filling material in the container becomes too uneven. This may occur, for example, if the residue sticks to the inner walls of the container when it is emptied, or if a single cone of bulk material is too pronounced during filling. Thus, when a signal is present, cleaning of the container may be initiated or the filling material may be redistributed, for example by means of a stirring mechanism. Furthermore, for example, based on the determined difference, two distance values d of the surface of the filling material corresponding thereto may be calculated_i，jA gradient or slope between the locations of (a). Such information may be used, for example, to be able to determine the taper or angle of a possible bulk material cone.

Based on the recording of the 3D camera, in addition to the filling level verification, other properties of the filling material may also be determined depending on the design. If the evaluation circuit is designed to determine the scattering, for example from the recorded distance values of the selected parts of the area, it can be envisaged that the evaluation circuit determines the roughness of the surface of the filling material from the determined scattering. If the type of filler material is known, the particle size or similar variables can be derived therefrom, for example.

Instead of or in addition to the scattering, the (standard) deviation from the mean or median of the distance values recorded by the 3D camera can optionally also be determined. Thus, in addition to or instead of determining the filling level based on the distances measured by the radar module (which verifies based on the maximum and minimum distance values), the distances measured by the radar module may also be verified based on a median or average value: if the distance to the surface of the filling material measured by the radar module is below a predefined (standard) deviation from the median or average of the distance values recorded by the 3D camera, the filling level will be determined based on the distance.

Depending on the type of 3D camera, it may be designed to additionally generate a grayscale image of the surface of the filling material in the region where the 3D camera determines the distance value. This can be used advantageously within the scope of the invention, for example, in order to simultaneously record a grayscale image when outputting the warning signal. In the event of an error, the plant operator or service technician can therefore search for the potential cause of the error within the container. In a grayscale image, the cone of radar signals may be visualized as, for example, a target circle or cross. The current orientation of the fill-level measuring device may thereby be tracked, or this may assist the orientation of the fill-level measuring device during assembly, for example in order to "guide the radar signal through" any interfering bodies.

A further advantageous further development of the fill-level measuring device provides for the evaluation circuit to be designed to detect the contour on the basis of the recordings within the area if a discontinuity between the distance values on both sides of the contour is detected along the contour. This would be useful for determining the internal cross-section, in particular the internal cross-sectional area, of the container based on the detected profile. But in addition it may also be the outline of other objects such as a stirrer. In particular, when the evaluation circuit is designed to detect movements and/or displacements of the contour, a movable object, such as a stirrer, can be positioned as such.

With the aid of a 3D camera, it is also conceivable to design the evaluation circuit in order to determine the orientation of the fill-level measuring device relative to the vertical. This is possible if a substantially flat plane, such as the surface of the fluid filling material, can be determined based on the recording within the area. The normal vector of the plane can thus be determined. Since in the case of a fluid filled material the resulting plane is horizontal, the determined normal vector corresponds to vertical. This in turn makes it possible to determine the orientation of the fill level measuring device relative to the vertical. This can be advantageously used for the installation of the fill level measuring device, since a precise vertical alignment of the radar module is advantageous for its safe operation. When the fill level measuring device is mounted on a display of the fill level measuring device or a display of a peripheral device, the current alignment or deviation from the vertical may be visually indicated.

Similar to the filling level measuring device according to the invention, the object on which the invention is based is solved by a method for determining a filling level of a filling material located in a container by means of a filling level measuring device according to one of the preceding embodiments. The method comprises the following method steps:

determining a distance to the surface of the filling material based on reflected radar signals emitted by the radar module in the direction of the filling material,

determining a plurality of distance values based on a recording of a 3D camera of at least one area of the surface of the filling material,

determining a maximum distance value and a minimum distance value from the distance values by means of an evaluation circuit,

-determining, by the evaluation unit, the filling level based on the distance if the distance is smaller than the maximum distance value and larger than the minimum distance value.

Drawings

The invention will be explained in more detail with reference to the following figures. Shown below:

FIG. 1: a schematic view of a filling level measuring device according to the invention on a container with filling material,

FIG. 2: a top view of the filling material from the perspective of the filling level measuring device according to the invention, an

FIG. 3: different measurement values depending on different measurement conditions.

Detailed Description

For understanding the invention, fig. 1 shows the arrangement of a filling level measuring device 1 according to the invention on a flange connection of a container 2, as is customary for radar-based filling level measuring devices. In the container 2 there is a filling material 3 whose filling level L is to be determined by the filling level measuring device 1. For this purpose, the filling level measuring device 1 is mounted on the container 2 above the filling material 3 at a known mounting height h. In this case, the container 2 may be more than 100m high, depending on the type.

The filling level measuring device 1 is aligned and fastened to the container 2 such that it emits a radar signal S continuously, periodically or non-periodically in the surface direction of the filling material 3 by means of a radar module 11_R. Due to radar signal S_RReflection at the surface of the filling material, the radar module 11 of the filling level measuring device 1 receives the distance D to the surface of the filling material after a corresponding operating time_RReflected radar signal S as a function of h-L_R。

Typically, the filling level measuring device 1 is connected to a superordinate unit 4, such as a process control system, via an interface, such as "PROFIBUS", "HART" or "wireless HART". In this way, the filling level value L can be transmitted, for example in order to control the flow or the discharge of the container 2 when necessary. However, other information about the overall operating state of the filling level measuring device 1 may also be transmitted.

If the radar module 11 is operated by the pulse radar method, the radar signal S_RWill be a radar pulse, possibly periodically transmitted, so that the pulse-like radar signal S can be directly based on the transmission of the pulse and the reflection_RThe pulse propagation time therebetween to determine the distance D_RAnd thus the filling level L.

In the case of FMCW radar, the radar signal S_RIs a continuous signal but with a time-defined modulation frequency. Thus, it may be based on the currently received radar signal S_RWith simultaneously transmitted radar signals S_RThe instantaneous frequency difference between to determine the propagation time and, hence, the distance D when implementing the FMCW method_ROr fill level L. With both radar methods, it is possible according to the prior art that the ideal conditions (well-reflecting filling material 3, flat filling material surface, absence of obstacles, such as stirrers, or radar signal S) are already present_RSignal path ofOther internal features in the diameter) addresses the fill level L with an accuracy in the sub-micron range. Even in the case of rough or wrinkled or packed material surfaces or dusty atmospheres, it is possible to reliably measure the filling level L at a certain point on the packed material surface by means of the above-described radar method.

However, when the surface of the filling material 3 is not flat, the periodic measurement of the filling level L by means of the above-mentioned radar method exceeds its limit. This may occur in particular in the case of bulk material 3 of the filling material, for example when a bulk cone is formed during filling of the container 2. When the filling material 3 is pumped out, depressions may occur on the surface of the filling material. Since the filling level is only periodically determined by means of the radar module 11 at a certain point on the surface of the filling material 3, this may lead to an incorrect interpretation of the filling level L. For example, even if there is still filling material 3 at the edge of the interior of the container, the emptying operation may be stopped when the radar module 11 detects an empty container 2. In the opposite case, when the container 2 is full, it may happen that the maximum filling level L has been exceeded even at a certain position on the surface of the filling material_maxThe filling operation is also not stopped, since this is not detected by the radar module 11.

Thus, according to the invention, the filling level measuring device 1 shown in fig. 1 comprises, in addition to a transmitter for transmitting and receiving radar signals S_RIncludes a 3D camera 12 in addition to the radar module 11. Similar to the radar module 11, the 3D camera 12 is arranged and oriented such that R can be recorded by means of recording of the 3D camera 12 filling the surface or at least a region of the surface of the material 3_3D. In this case, as can be seen from the top view of the surface of the filling material in FIG. 2, R is recorded_3DFrom a plurality of distance values d_i，jA plurality of distance values d_i，jIs present in the recording area [ m; n is]Corresponding pixel or location [ i, j ] within]As a function of (c).

In principle, the distance value D is additionally determined by the 3D camera_i，jAdding redundancy to the fill-level measuring device 1: the distance value d can be adjusted_i，jAt a distance D determined by the radar module 11_RA comparison is made. To this endCan be based on the distance value D of the 3D camera_i，jDetermining a maximum distance value d_maxAnd a minimum distance value d_min. If the distance D is_RLess than a maximum distance value d_maxAnd is greater than the minimum distance value d_min(as shown in part (a) of fig. 3), this may be interpreted as a distance D to be determined by the radar module_RAnd (4) verifying. If the verification is unsuccessful, i.e. the distance D determined by the radar module 11_RLess than a minimum distance value d_minOr greater than the maximum distance value d_max(as shown in part (b) of fig. 3), the filling level measuring device 1 may, for example, send a first warning signal s_f1Output to the superordinate unit 4. The reason for this may be, for example, that the radar module does not receive the radar signal S generated as an echo from the surface of the filling material_RBut rather unwanted echoes, such as multiple reflections for example, are received.

This type of verification can be applied to both flat and non-flat filler material surfaces. In general, the ability to verify the ascertained filling level L represents an advantageous characteristic of the filling level measuring device 1, since it is possible to meet one of the required specifications regarding functional safety, for example the IEC61508 standard. In many applications, compliance with the respective standard is in turn a prerequisite for allowing the use of the fill-level measuring device 1 for the respective application.

In the filling level measuring device 1 shown in fig. 1, an evaluation circuit 13 is provided for the distance D_RAnd verifies the distance value d_i，jAt a distance D determined for this purpose by the radar module 11_RA comparison is made. In this case, the evaluation circuit 13 may be implemented, for example, as a microcontroller, wherein the distance value D may be retrieved from the radar module 11 or the 3D camera via a corresponding input_i，jAnd a distance D_R. On the output side, the evaluation circuit 13 can be connected to the superordinate unit 4 in order to transmit a corresponding first warning signal s, for example in the event of a verification failure_f1。

Recording R on the surface of the filling material shown in FIG. 2_3DIn (c), the case is shown where the surface of the filling material is not flat but has a bulk material cone (see also fig. 1). In outlineThe form shows the contour of the bulk material cone or the surface of the filling material. Thus, the minimum distance D detected by the 3D camera_minAt the tip of the bulk material cone. In an alternative explanation of fig. 2, the contour line of the filling material surface may also represent a concave funnel, such that the maximum distance D ascertained by the 3D camera 12_maxRepresenting the deepest point of the depression.

Even on flat surfaces, such as in the case of a fluid filling material 2, the additional 3D camera 12 may produce a beneficial synergistic effect: for example, the evaluation circuit 13 can be designed to determine the orientation of the measuring level measuring device 1 relative to the vertical. This may be done, for example, by mathematically defining a plane and based on the distance value d_i，jDetermining record R_3DM is; n is]Its normal vector within the region is calculated. Since the resulting plane is horizontal for the fluid filling material 3, the normal vector corresponds to vertical. Due to reflection of radar signal S_RIs advantageous in that a precise vertical alignment of the radar module 11 is achieved, so that it is appropriate to first determine the orientation relative to the vertical during all installations of the fill level measuring device 1. For example, when the fill level measuring device 1 is mounted on its display or the display of a peripheral device, the vertical current orientation can be displayed.

Except for the determined distance D_RApart from a pure verification of d, the distance value d_i，jRecord R of_3DFurther synergistic effects are also provided: by comparing the distance value d_i，jFurther analysis of (2) can detect other irregularities in the container 2: therefore, by means of the maximum distance value d_maxAnd a minimum distance value d_minDifference Δ d and/or minimum distance value d between_minAnd a maximum distance d_maxMay be concluded that, for example, there may be deposits of bulk material cones, sunken funnels or filling material 3 on the walls of the container 2. In this case, a corresponding warning signal s may be generated_f1，...，s_fnIn particular when exceeding a predefined maximum range ad_max(schematically shown in part (c) of fig. 3) is determined. In addition to this, the present invention is,two distance values d corresponding thereto_i，jMay be calculated, for example, based on the difference ad, in order to be able to determine the taper of any bulk material cone, for example.

If the 3D camera is designed for this purpose, at least in the output of a warning signal s_fnIn those cases, the 3D camera may additionally record (on the display of the filling level measuring device 1, or for example on the display of an external mobile radio device) the area of the filling material surface [ m; n is]The gray scale image of (1).

FIG. 2 does not show the record R in FIG. 2_3DThe internal cross-section of the container 2 is also covered. In this case, the evaluation circuit 13 can be designed, for example, on the basis of the record R_3DAn internal cross-section is determined. In this case, the internal cross-section can be detected by recording R_3DIn which the evaluation circuit is recording R_3DThe corresponding contour is searched in. In this case, a "contour" is defined, since the corresponding distance value d between two sides of the contour can be determined along the contour_i，jI.e. "kinking" or jumping.

In this connection, in the simplest case, two distance values d can be passed_i，jExceeds a predefined value to mathematically detect two distance values d that may be separated by a contour_i，jThe jump in between. In contrast, two distance values d between which the contour extends are determined_i，jThe "kink" between is not so easy: for this purpose, the distance values d can be set further outward in each case with respect to the contour_i，jAre included so that the variation or "gradient" between them is calculated. In this case, two distance values d_i，jThe abrupt change in slope between them refers to the course of the contour between them. For this purpose, the corresponding analytical or numerical methods that can be implemented in the evaluation circuit 13 are sufficiently known.

If the internal cross-section of the container 2 is determined in this way, the internal cross-sectional area of the container 2 can be deduced on the basis thereof. This in turn may be used to base the determined distance value ond_i，j(or based on the distance D determined by the radar module 11 if the filling material 3 has a flat surface_R) To calculate the volume actually occupied by the filling material 3 in the container 2). This provides the advantage that any variation in the internal cross-section of the container 2 in the calculation of the volume can also take into account the height h. Needless to say, this type of volume calculation can be applied not only to the case of a circular inner cross section, as shown in fig. 2.

When the evaluation circuit 13 detects a contour, the contour can be assigned not only to the inner cross section of the container 2. If at the recording of R_3DIn the inner vessel 2 there are disturbances such as stirrers or inlets/outlets, which can also be represented as a record R_3DOf (2). In the case of a rotary mixer, the profile of the movement can be distributed accordingly. In this way, for example, the distance value D measured by the radar module 11_R(its distance value d from the value enclosed by the contour)_i，jCorresponding) may be classified as erroneous.

If the evaluation circuit 13 can perform contour recognition, there is a further possible application in addition to detecting disturbances and determining the internal cross section of the container: when the filling level measuring device 1 is attached to a circular connection, such as for example a flange (see fig. 1), a possibly detected contour can also be assigned to the flange opening. Those distance values d assigned to the contour_i，jCan be used to determine the distance D by the radar module 11_R: radar signal S received after reflection_R(which in the case of both pulse radar and FMCW methods is time-dependent and thus distance-dependent) and therefore can only be at the distance value d corresponding to the flange_i，jEvaluation is made in order to mask the radar signal S received from the area_ROf the interference component.

List of reference numerals

1 filling level measuring device

2 Container

3 filling material

4 upper unit

11 radar module

123D camera

13 evaluation circuit

D_RDistance determined by radar module

d_i，jDistance values determined by a 3D camera

d_maxMaximum distance value

d_minMinimum distance value

m; n receiving area

H installation height

L filling state

L_maxMaximum fill level

S_RRadar signal

s_f1，s_fnNotification signal

Delta d difference

Δd_maxMaximum range