Device and method for checking the stability of masts

Abstract

The invention relates to a device (10) for checking the stability of at least one mast (12). The invention is characterised by the inclusion of at least one camera (14), which is directed to the mast (12) and is operable by an operator from a ground position (16), and an upper part (18) of the mast (12) is imaged on a camera image (15). Alternatively, at least one camera (14) can be arranged on the upper part (18) of the mast (12), the camera image (15) showing a base part of the mast (12) or a part of the surroundings of the mast (12), such that a relative movement between the base part and the upper part (18) of the mast (12) can be determined. The invention also relates to a method (40) for checking the stability of at least one mast (12) by identifying plastic deformation of the mast (12), in particular using a device (10) according to the invention.

Description

[0001] DEVICE AND METHOD FOR CHECKING STABILITY

[0002] FROM MASTS

[0003] The present invention relates to a device for checking the stability of at least one mast. Furthermore, the invention relates to a method for checking the stability of at least one mast.

[0004] STATE OF THE ART

[0005] To ensure the stability of masts, they must be tested on-site. This is usually done by deliberately exciting the mast, i.e., causing it to vibrate, and then examining or observing its behavior based on the excitation. This can be used, for example, to determine whether the mast base is sufficiently securely anchored in the foundation. Furthermore, the flexural flexibility of the mast itself can be assessed.

[0006] The mast to be tested can be a mast for any purpose, such as a power or telephone mast, an antenna mast, a flagpole, a lamppost, or a traffic light or road sign mast. Likewise, the mast to be tested can be a mast for an overhead railway line or the tower of a wind turbine. The mast can be made of various materials, such as concrete, reinforced concrete, steel, wood, plastic, or a combination of different materials.

[0007] The mast can be made of solid material or have a hollow cavity. Masts typically have a circular or oval cross-section, which may, for example, taper along their length. However, the mast to be tested can also have an angular cross-section, such as a square or rectangular one. The diameter of the mast can also be constant along its entire length, or it can decrease from the base of the mast to the top.

[0008] The mast base is usually anchored in the ground, for example, by a foundation, which must ensure the mast's stability. Due to space constraints, guying the mast, especially from the mast tip, is usually unsuitable for stabilization. Therefore, it must be ensured that the anchoring of the mast bus is sufficiently stable to ensure the mast's stability, especially during operation.

[0009] Various methods and devices are known in the art for testing the stability of masts. For example, a material test can be performed, particularly using an ultrasound technique. The disadvantage of this method is that only the lower section of the mast can be tested, and the foundation itself cannot be examined.

[0010] According to DE 19540 319 C1, the residual deflection after a mast excitation can be determined using a scale plate. The scale plate is attached to the mast at a height to be tested. A laser beam is directed onto the scale plate. The position of the laser beam is read relative to a calibration point after the mast has returned to rest following the deflection. The disadvantage of this method is that it is not possible to evaluate the vibration amplitude.

[0011] Another known method is to test the mast by applying a real force, such as that from an excavator, to the mast, and then recording a force-displacement diagram. The force-displacement diagram can be generated using various devices or methods.

[0012] For example, DE 100 62 795 A1 discloses a device for testing bending strength. A satellite navigation receiver mounted on the mast determines the mast's geographical data during a deflection. The measured data is wirelessly transmitted to a computer and evaluated. Furthermore, two satellite navigation receivers can be mounted at different heights on the mast.

[0013] Furthermore, DE 10 2005 08 033 A1 discloses a method in which sensors are attached to the mast to determine its acceleration. The disadvantage of testing using acceleration sensors is that they do not allow for absolute measurements, thus making it impossible to determine whether any deformation remains in the mast. Furthermore, the geometry and material data used to determine the resonance frequency to be tested are usually too imprecise, resulting in inaccurate test results.

[0014] The force-displacement diagram can also be created according to DE 20 2017 000 952 U1 using at least one laser attached to the mast. The laser beam is directed onto a semi-transparent projection surface and recorded by a camera. The projection surface is positioned at a horizontal distance from the mast.

[0015] US 2004 / 0107671 A1 discloses a device for testing the stability and flexural rigidity of a mast using a light beam from a laser light source located in the lower part of the mast as a "light pointer," which is registered by a camera. The camera records movements of light points from the laser light source on a surface attached to the upper end of the mast that occur when the mast moves relative to the vertical. For this purpose, a fiber-optic tube must be provided in the mast between the laser and the measuring surface. This limitation imposes significant structural restrictions, is costly, and precludes retrofitting.

[0016] WO 00 / 43768 A1 discloses a device for monitoring building structures using camera images. Camera images are used to inspect the building structure after an alarm previously triggered by another sensor device. Depending on the alarm threshold, false alarms or delayed monitoring may occur. Furthermore, various sensor devices must be physically mounted on a mast and their operational capability verified.

[0017] A disadvantage of existing methods and devices is that the testing process is very complex due to the installation of various sensors, lasers, or scale plates on the mast. For example, the sensors and lasers can only be mounted on the mast up to a certain height with manageable effort. In particular, deflections of the upper section of the mast, and thus also of the mast tip, cannot be measured using existing methods or devices, as attaching elements to the mast tip requires the use of a crane, scaffolding, or similar equipment and is extremely expensive. Furthermore, the areas around the mast are not always sufficiently accessible for larger structures.

[0018] The sensors or lasers to be mounted, as well as their mounts, can also cause damage to the mast, particularly to the component shell or surface of the mast, making the mast particularly vulnerable to water ingress. Based on the prior art, the object of the invention is to propose a device and a method for checking the stability of masts that overcome the aforementioned disadvantages.

[0019] This object is achieved by a device and a method according to the independent claims.

[0020] DISCLOSURE OF THE INVENTION

[0021] The invention relates to a device for checking the stability of at least one mast.

[0022] It is proposed that at least one camera be included which is aimed at the mast, wherein a camera image shows an upper region of the mast, or that at least one camera is arranged at the upper region of the mast, wherein the camera image shows a base region of the mast or an area in the vicinity of the mast. In both cases, a relative movement between the base region and the upper region of the mast can be determined. Since the greatest deflections occur in the upper region of the mast, this region provides the most and the most decisive information regarding a deflection and residual deformations. Therefore, a measurement in the upper region of the mast is crucial when checking stability.Since masts are usually slimmer in the upper section than in the base area, the proposed device can be used to check whether the mast returns exactly to its original position after being stimulated. For this purpose, a measurement of the upper "soft" section of the mast is essential.

[0023] In a preferred embodiment, the mast can be a tower of a wind turbine. The device can therefore be used, in particular, to examine and document the stability of wind turbines.

[0024] In a preferred embodiment, the device can also be permanently mounted on the mast in order to carry out monitoring continuously or over a specific period of time. In such a case, the at least one camera can also be permanently mounted in or on the upper region of the mast. The device can therefore serve as a fixed installation for permanent monitoring. In other words, a simple and precise determination of a relative movement between the ground region and the upper mast region is possible using the at least one camera. The device is therefore particularly suitable for monitoring conventional masts or lampposts. In particular, the method can also be used for monitoring wind turbines.

[0025] Since the at least one camera is mounted, particularly stationary, at a ground position, the installation or attachment of additional measuring instruments to the mast is eliminated. Damage to the mast can be prevented. Likewise, expensive attachments on the surface of the mast are eliminated. The camera can preferably be operated by an operator from a ground position.

[0026] The camera can be mounted in a position easily accessible to the operator, thus placing no special requirements on the mast's surroundings. The camera is preferably aimed at any position in the upper part of the mast, so that, for example, a section in the upper third of the mast is captured by the camera.

[0027] According to the invention, an optical vibration measurement can be carried out, which can also be carried out without contact with the mast to be measured.

[0028] The upper section of the mast can therefore be considered the upper third. Likewise, the upper section of the mast can be located in the upper fifth of the mast. In another embodiment, the upper section of the mast can form a special attachment at the top of the mast or a top of the mast, to which, for example, a bracket, a light, a traffic light, or a sign is attached.

[0029] The mast can be of varying heights. For example, the mast can be 8 m to 12 m high. In particular, the mast can be 10 m high.

[0030] The camera can be used, in particular, to generate a moving image to record the mast's vibration within the camera image as a film recording. In another embodiment, a sequence of still images can be generated, which are output at desired time intervals, for example. The time intervals can be hundredths or tenths of a second, so that the sequence of images can simulate the mast's vibration.

[0031] In a subsequent processing step, the recorded vibration can be evaluated using signal theory, specifically, it can be transformed into a spectral range using a digital transformation protocol such as DFT or FFT, and analyzed for eigenmodes, i.e., modes of the resonance system represented by the mast. Using standard numerical methods, an eigenvalue / eigenvector analysis can be performed to determine eigenmodes from the vibration pattern recorded by the camera. A change in eigenmodes while the structural measures remain unchanged is a strong indicator of structural changes and damage to the mast.

[0032] The proposed device can be used, in particular, to carry out absolute position measurements. For this purpose, it is advantageous if a picture of the initial situation is taken before the mast is excited, i.e. in particular before it starts to oscillate. After this, the camera should not be moved any further. If the mast is excited, for example in the area of ​​the mast base, the mast tip experiences the greatest deflection. This allows the measurement to be carried out with only a slight excitation of the mast, while at the same time damage due to excessive vibration amplitudes can be avoided. The vibration amplitude in the upper area of ​​the mast is recorded visually after the initial situation, in particular continuously or at desired time intervals. This allows checking, even after several vibration tests have been carried out, whether the mast returns exactly to its initial position after it has started to oscillate. This can be done with millimetre accuracy, i.e.in the millimeter range. Preferably, several oscillations occur in different directions, with the directions arranged in a horizontal plane.

[0033] In an advantageous embodiment, the camera image can show the upper end of the mast. The upper end of the mast can be understood, in particular, as the mast tip. A bracket for a cable can be arranged at the mast tip, for example.

[0034] In an advantageous embodiment, the camera can be aimed at the mast in such a way that the camera image shows the underside of a lamp holder. Since the lamp holder deforms together with the top of the mast and vibrates with the same vibration amplitude as the mast, the situation of the mast can be deduced from the observation of the lamp holder. If the lamp holder is filmed from below, an almost flat surface is available for observation, which means the measurement results are particularly precise. Furthermore, the camera can be arranged directly below the lamp holder at a ground position. The camera can be placed, for example, directly next to the base of the mast. Since the camera itself is very small, it can be adapted to different space conditions. Furthermore, the camera can be mounted at any position away from the base of the mast or the top of the mast.from the mast itself, providing a clear view of the lamp holder or the mast top. This makes the device completely independent of the space available on the mast being examined.

[0035] In an advantageous embodiment, a laser beam from a stationary laser can be directed at the area of ​​the mast captured by the camera, so that the laser beam is visible as a fixed point in the camera image. The laser is fixed independently of the mast, allowing the mast to exert a relative displacement to the laser beam. The laser can also be arranged at any position around the mast base or around the mast. Mounting the laser to the mast itself is not necessary. A relative movement of the mast can be calculated to the fixed point created by the laser beam. This is particularly advantageous if the camera should move during the measurement.

[0036] If the laser is mounted independently of the mast, the laser is not affected by the mast's movement. This ensures that the laser beam is always aligned exactly the same.

[0037] In an advantageous embodiment, at least one camera can be arranged in an area of ​​a mast that can be accessed from the inside and aimed at the ground area inside the mast, wherein the camera image shows an area inside the accessible mast. The camera can be the camera already explained above. Another camera can also be used. In such an embodiment, the at least one camera can be aimed from the upper area of ​​the mast at a ground area inside the mast and film this area. This makes it possible to determine a relative movement of the upper area of ​​the mast, which in particular allows conclusions to be drawn about its stability. The mast can in particular be the tower of a wind turbine.

[0038] In an advantageous embodiment, the camera can be a smartphone camera. Advantageously, this allows the entire recording during the test to be carried out using a smartphone alone. Preferably, the recording can then be evaluated using software. The software can, for example, be installed directly as an app on the smartphone. In this case, the evaluation can, in particular, also take place “just in time” during the recording. In an advantageous embodiment, a deflecting mirror element can be included, which serves to deflect the camera image so that the camera image shows an area of ​​the mast and the camera, in particular the camera of a smartphone, can be operated by the operator in an upright position. For example, a type of mirror can be used as a deflection element, by which the camera image is deflected. The at least one mirror is, in particular, arranged in such a way that advantageously the camera orthe smartphone remains operable, even if the camera image shows an upper area of ​​the mast or the lamp holder.

[0039] In a front-most embodiment, the camera can be arranged in a shielding element, thus preventing light from entering from the side. A type of shaft through which filming takes place can be used as the shielding element. The shaft is preferably clad or colored black, especially matte black, so that reflections can be avoided.

[0040] The invention further relates to a method for checking the stability of at least one mast.

[0041] A method is proposed that comprises creating a first image sequence and / or a first film recording using a camera over a period of time t1. The camera is stationary and aimed at an upper area of ​​the mast. In a further embodiment, the camera is arranged at an upper area of ​​the mast and aimed at a base area of ​​the mast or an area in the vicinity of the mast. In both cases, plastic deformation of the mast can be detected, in particular.

[0042] In one embodiment, therefore, only one vibration measurement can be carried out, during which a possibly occurring movement of the optical center of gravity of the mast, in particular adjusted for an oscillation amplitude, can be examined.

[0043] In particular, in a fixed installation for permanent monitoring, externally applied excitation, such as artificial force application or even just wind, can be used to monitor any long-term drift of the optical center of gravity captured by the camera. This can be used to determine or detect plastic deformation of the mast.

[0044] In a preferred embodiment, the mast can be excited before or after the first image sequence and / or the first film recording, causing it to oscillate for the first time. In this case, it can be examined, in particular, whether the optical center of gravity is the same before and after the single excitation.

[0045] In a preferred embodiment, an optical center of gravity of the natural mast movement and the excited oscillation can be determined before and after the excitation of the mast, and it is then checked whether the two centers of gravity coincide.

[0046] In a preferred embodiment, after the first image sequence and / or a first film recording has been created, the following steps can be carried out:

[0047] - further excitation of the mast so that it is set into a second oscillation, wherein the second oscillation is unequal to the first oscillation, in particular angled to the first oscillation (S1) and second oscillation (S2),

[0048] Creating a second image sequence and / or a second film recording using the camera over a period t2,

[0049] Determining an optical center of gravity of each oscillation from the first and second image sequences and / or film recordings,

[0050] Check that both centers of gravity match.

[0051] An embodiment of the method is characterized, for example, by the following steps:

[0052] - Stimulating the mast so that it is set into a first oscillation,

[0053] - Creating a first image sequence and / or a first film recording using a camera over a period of time t1, wherein the camera is fixed in position and is directed towards an upper area of ​​the mast,

[0054] - Excitation of the mast so that it is set into a second oscillation, whereby the second oscillation is not equal to the first oscillation,

[0055] - Creating a second image sequence and / or a second film recording using the camera over a period t2,

[0056] - Determining the optical center of gravity of each oscillation from the first and second image sequences and / or film recordings,

[0057] - Check that both centers of gravity match.

[0058] The same features and advantages apply to the method as described for the device. In particular, the method is also based on optical vibration measurement and can therefore be carried out without contact with the mast.

[0059] The time periods t1 and t2 can be chosen as desired. This period can be very long, allowing for virtually permanent monitoring of the mast, especially of a wind turbine.

[0060] In particular, a center of gravity of the vibration frequency or vibration excitation should be determinable within the respective time period. The center of gravity can be understood as a location to which the mast returns after the excitation has taken place or to which it remains at rest. During the excitation, the mast or a section of the mast therefore moves around this center of gravity and approaches it ever closer. If at least two excitations are started one after the other, each of which is filmed by the camera, two vibration movements can be observed for one and the same filmed section of the mast. Advantageously, the mast is set into differently oriented vibrations for the two time periods. This means, in particular, that the directions of the excitations are aligned differently in a horizontal plane.The oscillation can also be of varying magnitude in different horizontal directions, regardless of the nature of the mast and / or the direction of force application. Ideally, a circular or elliptical oscillation can be excited around the mast's center of vibration in order to stimulate the oscillation behavior in all spatial directions. If there is any residual deformation after the excitation, this can be determined by the fact that the two centers of gravity of the two determined image sequences do not coincide. If, on the other hand, the mast returns to the same initial position after each excitation, i.e. the two centers of gravity coincide, there is no residual deformation or deformation in the mast. It can therefore be concluded that the mast is sufficiently stable in the foundation.

[0061] In particular, the method can be used to capture or determine the position of the mast, or a section of the mast, at any given time using image processing. In particular, the image processing can be used to determine the deflection of a mast section in at least two directions within a plane. In particular, the deflection can be determined over a period of time. Using image processing, not only the relative deflection with respect to a reference point but also the absolute deflection for a specific area can be determined. The absolute deflection can be used to determine the actual elastic behavior of the mast during excitation.

[0062] In a preferred embodiment of the method, at least a third oscillation can be generated by exciting the mast, from which a third image sequence and / or a third film recording is generated by the camera over a period t3, the optical center of gravity of which is also compared with the previously determined optical centers of gravity. The third oscillation is preferably angled, in particular oriented at right angles to the first and / or second oscillation. This allows the accuracy of the method to be optimized.

[0063] An angle, especially an orthogonal angle, of the vibration excitation of the second or third oscillation relative to the first oscillation enables the holistic recording of as many natural oscillations of the resonant system as possible, thus enabling detection of all natural oscillations in 2D or 3D. This allows for reliable detection of structural damage that only causes a change in the vibration behavior in one spatial direction, since vibrations in multiple directions are observed and analyzed.

[0064] In a preferred embodiment of the method, the camera can be aimed at an upper end of the mast, in particular at a lamp support. In particular, an underside of the lamp support can be filmed. This allows the deflection of the lamp support to be recorded in a plane parallel to the ground or in a horizontal plane. Advantageously, this represents the greatest deflection on a mast with a lamp support, since the free end, at which the lamp support is arranged, deflects the furthest. If the deflection is determined at this point, the accuracy of the method can be improved.

[0065] In a preferred embodiment of the method, at least one laser beam can provide at least one stationary reference point on the image sequence and / or on the film recording. This reference point is visible as a fixed point in the recording. A relative movement or relative oscillation of the mast can be calculated with respect to this fixed point.

[0066] In a preferred embodiment of the method, a relative movement of the mast to the reference point and / or an unintentional movement of the camera can be determined. With the help of subsequent or parallel image processing, the actual movement or the actual vibration behavior of the mast can be determined even if the camera position changes, as long as the reference point is visible in the camera image.

[0067] In a preferred embodiment, at least two laser beams can provide at least two stationary reference points on the image sequence and / or on the film recording, so that a movement amplitude of the mast can be determined.

[0068] In particular, the magnitude of the movement amplitude can be easily calculated. For example, two lasers can be used. In a further embodiment, more than two lasers, in particular three to five lasers, can be used. In a preferred embodiment of the method, a signal can be output at a target vibration amplitude of the mast, and further excitation can be stopped. Advantageously, a real-time evaluation of the vibration amplitude can provide information about whether the mast has started sufficiently. This can prevent excessive loading or overstressing of the mast. Pre-damage to the mast caused by the method can therefore be avoided.

[0069] DRAWINGS

[0070] Further advantages will become apparent from the accompanying drawing description. The drawings illustrate exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.

[0071] It shows:

[0072] Fig. 1 two schematic representations of a mast with an embodiment of a device according to the invention;

[0073] Fig. 2 is a view of the underside of a lamp holder;

[0074] Fig. 3 is a schematic representation of a mast with a further

[0075] Embodiment of a device according to the invention;

[0076] Fig. 4 two possible projections of vibration excitations for two different masts.

[0077] Fig. 1 shows two schematic representations of a mast 12 with an embodiment of a device 10 according to the invention. Fig. 1 (a) shows a first embodiment of the device 10 for checking the stability of the mast 12. A camera 14 is directed toward an upper region 18 of the mast 12. The camera 14 is arranged independently of the mast 12 at a ground position 16 in the region of the mast 12. The camera 14 is fixedly positioned such that the camera image 15 is directed toward the upper region 18.

[0078] In this embodiment, the camera 14 is mounted on its own tripod and can be positioned anywhere in the area of ​​the mast base. In particular, the camera 14 is not in contact with the mast 12. The camera 14 can be a conventional digital camera. In another embodiment, the camera of a smartphone 32 can be used as the camera 14. In such an embodiment, the smartphone 32 is mounted on a tripod and aligned like the camera 14, as shown above.

[0079] Fig. 1 (b) shows a further embodiment of the device 10. The camera 14 is aligned directly vertically and positioned below a lamp holder 24. To prevent disruptive light incidence, a shielding element 34 can be arranged on the camera 14. This is shaped, for example, as a type of shaft. The camera 14 and the smartphone 32 are also arranged independently of the mast 12 and the mast base in this embodiment. In particular, a fixed position of the camera 14, independent of the mast 12, can provide a method 40 that is easy to implement and adaptable to different site conditions.

[0080] The mast shown can, for example, have a height of 8 to 12 m, in particular 10 m. The upper region 18 is understood to be the upper third of the mast 12. Measurement in this region is particularly efficient and particularly accurate, since the mast 12 experiences the greatest deflection at the upper region 18 or at the upper end 20 when it is clamped to the mast base and swung.

[0081] Fig. 2 shows a view of an underside 22 of a lamp support 24. It depicts the camera image 15, which can be generated in particular using an embodiment of the method 10 according to Fig. 1 (b). Consequently, any desired image sequence and / or film recording can be generated of the underside 22 of the lamp support 24 during an oscillation as well as when the mast 12 is stationary. Since the lamp support 24 is located at the uppermost end 20 of the mast 12, the camera image 15 can capture the greatest possible deflection of the mast 12.

[0082] Fig. 3 shows a schematic representation of a mast 12 with a further embodiment of a device 10 according to the invention. In contrast to the representation in Fig. 1, a laser 28 is arranged independently of the mast 12 and independently of the camera 14 at the ground position 16 in the region of the mast base. The laser 28 projects a laser beam 26 in the direction of the camera image 15. The laser beam 26 can be used to generate a reference point 29 as a fixed point 30 in the camera image 15, shown in Fig. 2. This makes it possible to calculate a relative displacement of the mast 12 or the lamp holder 24 to this reference point 29 by means of image processing. The image processing involves, in particular, a visual evaluation of the displacement of different image points between different recordings or at different points in time.

[0083] The embodiment in Fig. 3 further shows a deflecting mirror element 36, which serves to deflect the camera image 15. This allows the camera 14 or smartphone 32 to be arranged in a position that is easily accessible to an operator, even if the camera of the smartphone 32 or the lens of the camera 14 images the lamp holder 24.

[0084] Fig. 4 shows two possible projections of vibration excitations for two different masts. The upper illustration shows a mast that always returns to its initial position after different vibration excitations. This is evident from the fact that the determined centers of gravity SP1, SP2, SP3 are the same for the vibrations S1, S2, S3. The lower illustration shows a mast that, for example, has insufficient stability, is insufficiently anchored in the concrete foundation and / or experiences plastic deformation during the vibration. This is evident from the fact that the centers of gravity SP1, SP2, SP3 of the vibrations S1, S2, S3 are arranged in different positions.

[0085] According to the method 40 according to the invention or the device 10 according to the invention, the mast 12 is preferably excited in at least two different directions. This allows a direction-independent stability test to be performed.

[0086] List of reference symbols

[0087] 10 Device

[0088] 12 masts

[0089] 14 Camera

[0090] 15 Camera image

[0091] 16 Floor position

[0092] 18 upper area 0 upper end 2 bottom

[0093] 24 lamp holders

[0094] 26 laser beam

[0095] 28 lasers

[0096] 29 Reference point

[0097] 30 fixed point

[0098] 32 smartphones

[0099] 34 Shielding element

[0100] 36 Deflecting mirror element

[0101] 40 procedures

[0102] SP1 Focus

[0103] SP2 Focus

[0104] SP3 Focus

[0105] S1 oscillation

[0106] S2 oscillation

[0107] S3 oscillation

Claims

Claims: Device (10) for checking the stability of at least one mast (12), characterized in that it comprises at least one camera (14) directed at the mast (12), wherein a camera image (15) shows an upper region (18) of the mast (12), or that at least one camera (14) is arranged on the upper region (18) of the mast (12), wherein the camera image (15) shows a base region of the mast (12) or a region in the vicinity of the mast (12) such that a relative movement between the base region and the upper region (18) of the mast (12) can be determined. Device (10) according to claim 1, characterized in that the camera image (15) shows the upper end (20) of the mast (12). Device (10) according to claim 1 or 2, characterized in that the camera (14) is aligned with the mast (12) such that the camera image (15) shows an underside (22) of a lamp holder (24).Device (10) according to one of the preceding claims, characterized in that a laser beam (26) of a stationary laser (28) is directed towards the area of ​​the mast (12) that is captured by the camera (14), such that the laser beam (26) is visible as a fixed point (30) in the camera image (15), wherein, in particular, the laser (28) is fixed independently of the mast (12), so that the mast (12) can exert a relative displacement to the laser beam (26). Device (10) according to claim 4, characterized in that at least one camera (12) is arranged in an area of ​​a mast (12) accessible from the inside and is directed towards the ground area inside the mast. (12) is aligned, the camera image showing an area within the walkable mast (12). Device (10) according to one of the preceding claims, characterized in that the camera (14) is a camera of a smartphone (32). Device (10) according to one of the preceding claims, characterized in that the camera (14) is arranged in a shielding element (34) so ​​that lateral light incidence is avoided. Device (10) according to one of the preceding claims, characterized in that a deflecting mirror element (36) is included, which serves to deflect the camera image (15) so that the camera image (15) shows an area of ​​the mast (12) and the camera (14), in particular the camera of a smartphone (32), can be operated by the operator in an upright position.Method (40) for checking the stability of at least one mast (12), in particular with a device (10) according to one of claims 1 to 8, characterized by:. - Creating a first sequence of images and / or a first film recording using a camera (14) over a period of time t1, wherein the camera (14) is directed towards an upper region (18) of the mast (12) or is arranged on an upper region (18) of the mast (12) and directed towards a base region of the mast (12) or a region in the vicinity of the mast, so that in particular a plastic deformation of the mast (12) can be detected. Method (40) according to claim 9, characterized in that before or after the creation of the first sequence of images and / or the first film recording, the mast (12) is excited so that it is set into a first vibration (S1). Method (40) according to claim 10, characterized in that an optical center of gravity (SP1, SP2) of the natural mast movement and the excited vibration (S1) is determined before and after excitation of the mast (12), and it is then checked whether the two centers of gravity (SP1, SP2) coincide. Method (40) according to claim 9 or 10, wherein, after the creation of the first image sequence and / or a first film recording, the following steps are carried out: - further excitation of the mast (12) so that it is set into a second oscillation (S2), wherein the second oscillation (S2) is not equal to the first oscillation (S1), in particular angled to the first oscillation (S1), - Creating a second image sequence and / or a second film recording using the camera (14) over a period of time t2, - Determining an optical center of gravity (SP1, SP2) of each oscillation (S1, S2) from the first and second image sequences and / or film recordings, - Check whether both centers of gravity (SP1, SP2) coincide. Method (40) according to one of claims 9 to 12, characterized in that at least a third oscillation (S3) is generated by excitation of the mast (12), in particular angled to the first oscillation (S1) and second oscillation (S2), from which a third image sequence and / or a third film recording is generated by means of the camera (14) over a period of time t3, the optical center of gravity (SP3) of which is likewise compared with the previously determined optical centers of gravity (SP1, SP2). Method (40) according to any one of claims 9 to 13, characterized in that the camera (14) is directed towards an upper end of the mast (20), in particular towards a lamp holder (24). Method (40) according to any one of claims 9 to 14, characterized in that at least one laser beam (26) provides at least one fixed reference point (29) on the image sequence and / or on the video recording. Method (40) according to claim 15, characterized in that a relative movement of the mast (12) to the reference point (29) is determined and / or an unintentional movement of the camera (14) can be detected. Method (40) according to any one of claims 9 to 16, characterized in that at least two laser beams (26) provide at least two fixed reference points (29) on the image sequence and / or on the video recording, so that a movement amplitude of the mast (12) can be determined.Method (40) according to claim 17, characterized in that a signal is output and further excitation is stopped when a target vibration amplitude of the mast (12) is reached.