Aid for holding and positioning a measuring sensor or measuring device and the method applied thereto

Abstract

Device for positioning a measuring sensor against a surface, characterized by the fact that the device comprises the following elements: - an elongated base element, - an extension; - a holder connected to the extension, where movable connecting elements are provided between the base element and the holder, comprising one or more of the following: - a friction joint, - one or more flexible zones; where the holder is provided with means for pressing the holder against the surface to be measured.

Description

2 In ultrasonic measurements, the measuring system is usually implemented in such a way that there is a gap between the measuring surface of the measuring sensors and the surface to be measured. For thickness measurement of, for example, steel plates, a coupling fluid is required to ensure efficient transmission of ultrasonic waves between the measuring surface of the measuring sensor and the steel surface. This is a consequence of the physical properties of ultrasonic waves and the interaction with the various media. The coupling fluid prevents air entrapment, improves signal quality, ensures efficient signal transmission, and reduces wear on the measuring surface of the measuring sensor. The coupling fluid is applied between the measuring surface and the surface to be measured so that this gap is filled with coupling fluid and effective measurement can be taken. In known systems, the coupling fluid is applied to the surface to be measured or to the measuring surface of the measuring sensor. Subsequently, the measuring sensor is pressed onto the surface to be measured. However, this has the disadvantage that the measuring surface of the measuring sensors wears becausethe measuring sensor must be pressed carefully against the surface to be measured. It is inevitable that the measuring surface of the measuring sensor and the surface to be measured will shift relative to each other and rub against each other prior to or after the coupling, causing the measuring surface of the measuring sensor to wear out. Naturally, many of the surfaces or objects to be measured are located at great heights or are difficult to reach. BE2025 / 5018 3 This means that the person who has to perform the measurement often has to work at great heights using, for example, ladders, scaffolding, or aerial work platforms, which is naturally not without danger. Moreover, the use of, for example, an aerial work platform is very expensive and time-consuming. In narrow or difficult-to-reach places or places with weak ground, this is also often impossible. Erecting scaffolding or platforms is often even more time-consuming and expensive. To avoid the use of ladders, scaffolding, platforms and aerial work platforms, telescopic measuring poles are therefore sometimes used, on which a measuring sensor or 15 is mounted.measuring instrument can be attached in a holder provided for that purpose. The disadvantage of these measuring sticks, however, is that the angle between the holder and the measuring stick is usually not adjustable.20 Even if this angle is adjustable, the user must estimate the angle between the holder and the measuring stick in advance and secure it so that the measuring surface lies as parallel as possible to the surface to be measured. This often requires multiple iterations,25 which is time-consuming and frustrating for the user. Another disadvantage is that after measuring a first surface, the angle must be readjusted when a second surface to be measured is at a different angle or degree of inclination than the first surface. In other words, the user must bring the holder back to the ground by tilting the measuring stick or by shortening the measuring stick or sliding it into the card when the measuring stick is telescopic. 5 This means that measurements take a lot of time because each measurement requires a separate setting, which often also requires multiple iterations.Moreover, many surfaces are inaccessible with the known measuring sticks. For example, the thickness of the roof of a tank or silo that needs to be measured from the outside and from the ground. Another disadvantage of the known measuring sticks or tools for holding and positioning a measuring sensor or measuring device against an object or surface to be measured is that measurements on curved or bent surfaces are inaccurate because the measuring surface makes insufficient contact with the surface to be measured. The present invention aims to offer a solution to the aforementioned disadvantages. This concerns an aid for holding and positioning a measuring sensor or measuring device against an object or surface to be measured, characterized in that the aid comprises the following elements: - an elongated base element, suitable for being held by a user;30 BE2025 / 5018 5 - an extension piece hinged to the base element by means of a first hinge provided at one end of the base element that is furthest removed from a user in use;5-a holder for holding a measuring sensor or measuring device, whereby the holder is connected to the extension near a free end that is furthest removed from the aforementioned first hinge, whereby one or more movable connecting elements are provided between the base element and the holder, all such that a relative movement is possible between the base element and the holder through deflections and / or rotation of the one or more movable connecting elements, which movable connecting elements comprise one or more of the following: -a friction joint, -one or more flexible zones; whereby the holder is provided with means for pressing the holder against the object or surface to be measured. The extension hinged to the base element ensures that, when a measuring sensor is placed in the holder, the measuring sensor can perform measurements in as many, if not all, possible surfaces as possible without the user or operator having to change position. The extension ensures that the first hinge is at 30a distance from the holder is brought such that any BE2025 / 5018 6 obstacles under the surface or object to be measured are not obstructive. At the same time, thanks to this distance between the first hinges and the holder, the angle between the base element and the vertical line (which intersects the plane formed by the ground at an angle of 90° or is parallel to gravity) can be kept very small during use. This means that the tool is also very suitable for use in tight spaces or narrow passages and / or in spaces where many obstacles are present in the vicinity of the surface or object to be measured. However, the ease of use, deployability, and flexibility are further enhanced by the presence of one or more movable connecting elements. Thanks to these movable connection elements, the measuring sensor is also much easier to handle and maneuver at height or at a certain distance from the user. Thanks to the aid according to the invention, the measuring surface of the measuring sensor is much easier to bring into contact with thethe surface or objects to be measured and this at all possible angles or planes without the user having to change position. Thanks to movable connecting elements, the measuring sensor can also measure a wide range of surfaces with mutually different orientations in succession without the user having to adjust the opening angle of the first hinge each time or without other settings having to be adjusted. This ultimately results in enormous time savings when multiple surfaces or objects with mutually different orientations need to be measured in succession. Furthermore, after setting the opening angle of the first hinge, no further iterations are required to bring the measuring surface of the holder into good contact with the surface or object to be measured. The small variations in angle or orientation that might still be necessary can be accommodated by the movable connecting elements. 15 Moreover, bringing the measuring surface of the measuring sensor into contact with the object to be measured has been greatly simplified and made more user-friendly thanks to the meansfor pressing the holder against the surface to be measured. This is discussed in more detail in the 20 description of the figures. The basic element is preferably telescopic and comprises at least two segments that can slide telescopically relative to each other or into each other. 25 This allows the greatest possible distance to be bridged in use, but the tool is still easy to handle in small or low spaces and can also be easily transported. 30 BE2025 / 5018 8 The holder is preferably configured for holding a measuring device or measuring sensor or equipped with a measuring device or measuring sensor. A measuring device or measuring sensor can, for example, be an ultrasonic measuring sensor, suitable for thickness measurement of objects or structures 5 such as plates, profiles, walls, pipe walls, walls of tanks or silos and the like. However, the invention is not limited to this. In a preferred load-bearing design, the holder10 is also equipped with a small camera. This allows the user operating the aid or someone else tomeasuring process of ground-mounted monitoring. The camera generally provides more visual control and makes it easier for the user, among other things, to position the measuring sensor at exactly the desired position on the surface to be measured. The invention also relates to a method for operating the device according to the invention. The method according to the invention comprises the following steps: a) optionally attaching a measuring sensor or a measuring device to the holder of the device; b) optionally adjusting and locking the opening angle of the first hinge;25 c) moving the holder in the direction of the surface to be measured or moving the holder close to the surface to be measured until the desired location / value measurement is reached on the surface to be measured;30 BE2025 / 5018 9 d) subsequently bringing the holder into contact with the surface to be measured so that a point of contact is created between the holder and the surface to be measured, either in such a way that an angle β exists between the plane K formed by the measuring surface of the measuring sensors and the plane L formed by the surface to be measuredsurface; e) pushing away, repelling, or extending the base element so that a moment M is created around the aforementioned point of contact, such that under the influence of the means of pressing the holder, the plane K formed by the measuring surface of the measuring sensor and the plane L formed by the surface to be measured become essentially parallel.15 Optionally, prior to step c), the base element can be brought to the correct length by shifting and securing one or more telescopic segments of the base element.20 Optionally, step f) can be followed by a step f) in which coupling fluid is injected between the plane K formed by the measuring surface of the measuring sensor and the plane L formed by the surface to be measured.25 This step f), which takes place only after coupling, has the advantage that the measuring surface of the measuring sensor does not wear out. Thanks to the configuration of the holder and the means, the measuring surface does not come into direct contact.30 with the surface to be measured. Through this, measuring sensors BE2025 / 5018 10 last much longer than with the known measuring sticks oraids for holding and positioning a measuring sensor or measuring device against an object or surface to be measured. For this, prior to coupling, the coupling fluid is first applied to the surface to be measured5 or to the measuring surface of the measuring sensors and subsequently the measuring sensor is pressed onto the surface to be measured, resulting in wear of the measuring sensor. Optionally, prior to step c), the base element can be brought to the correct length by sliding and securing one or more telescopic segments of the base element. With the insight to better demonstrate the characteristics of the invention, hereafter, as an example without any restrictive character, a preferred form of execution is described of an aid for holding and positioning a measuring sensor or measuring device against an object or surface to be measured according to the invention, with reference to the accompanying drawings, in which: Figure 1 schematically and in perspective shows a first variant of an aid for holding and positioning a measuring sensor or measuring device againstdepicts an object or surface to be measured according to the invention; figure 2 depicts a view according to arrow F2 in figure 1;30 BE2025 / 5018 11 figure 3 depicts a variant according to the invention in perspective and in use; figures 4 to 6 depict the use of the tool according to the invention in three different situations, where the thickness of flat surfaces5 is measured; figure 7 depicts a detail according to arrow F7 in figure 4 but on a larger scale; figure 8 schematically and in perspective depicts a second variant of a tool according to the invention10, where the thickness of a tube is measured; figure 9 depicts the second variant according to figure 8 for thickness measurement of an outer bend of a tube; figure 10 depicts the second variant according to figure 815 for thickness measurement of an inner bend of a tube; figure 11 depicts a third variant of a tool according to the invention; Figure 12 schematically depicts the fourth variant of an aid according to the invention in a first use position; Figure 13 depicts the fourth variant of Figure 12 in a second use position;Figure 14 schematically depicts steps a) to c) of a method according to the invention; Figure 15 depicts step d) of a method according to the invention; Figure 16 depicts step) of a method according to the invention; BE2025 / 5018 12 Figure 17 depicts a position of use of the invention in which the steps a) to c) of the method were followed. The device shown in Figure 1 mainly comprises a base element 2, an extension 3, a first hinge 4, a holder 5 and a movable connecting element 6. The base element 2 is an elongated element which 10 is configured to be held by a user 7. The extension 3 is hinged to the base element 2 by means of the first hinge 4 which 15 is provided at one end of the base element 2. The end at which the first hinge 4 is provided is, in use, the furthest away from the user 7. A free end of the extension piece3, which free end20 is furthest removed from the first hinge 4 when in use, is provided with the holder5 for attaching a measuring sensor or measuring device8.The opening angle of the first hinge4 is pre-set in this example by the user7 using muscle power, but in other designs the opening angle of the first hinge4 can also be set and changed remotely and in various ways, for example hydraulically, pneumatically, mechanically or30 electrically. BE2025 / 5018 13 The first hinge4 in this example is designed as two concentric discs4A,4B with interlocking teeth9 on the edges of the discs. The rotation of the discs can be locked at the5 desired opening angle. In this case, the extension3 is partially designed as a movable connecting element6. Alternatively, the extension3 can be fully designed as a movable10 connecting element6 or a movable connecting element6 can be installed between the first hinge4 and the extension3 and / or between the extension3 and the holder5. 15 The movable connecting element 6 enabled a relative movement between the base element 2 and the holder 5 due to deflection and rotation of the movableconnecting element 6. Alternatively, it may be that only a bend or only a rotation is possible. 20 In this case, the movable connecting element 6 is designed as a flexible zone 9 in the extension 3. The flexibility coefficient or compliance of the entire extension 3 and holder 5 is equal to 25 mm / N in this example. In practice, this value lies between 10 mm / N, inclusive 10 mm / N. Alternatively, the flexibility coefficient or compliance of the entire extension 3 and holder 5, including measuring sensor or measuring device 8, may lie between 10 mm / N, inclusive 30 and 10 mm / N. BE2025 / 5018 14 This range of flexibility coefficient of compliance ensures that the angle or rotation between the holder5 and the base element2 can be easily varied by the user7. In the example shown, muscle force5 of the user7 is sufficient, but in other configurations this can be done with the aid of an actuator operated by the user7. Such an actuator can be hydraulically, pneumatically, mechanically or electrically actuated. 10In this case, the flexible zone9 is made of an elastomer, but in practice, this can also be polyurethane, polyvinyl chloride in combination with one or more plasticizers, ethylene-vinyl acetate, or a combination of one or more of the aforementioned materials.15 Alternatively, or in addition to the materials mentioned above, the one or more flexible zones9 can also be provided with one or more springs, for example coil springs, so that angular displacement / or rotation20 is possible of the holder relative to the base element 2. Alternatively, the movable connecting element6 can also be designed as a friction joint in the form of25 a ball joint or an elbow joint. This friction joint can then, for example, be provided between the holder5 and the extension3. Such a friction joint has three degrees of freedom and ensures that the holder maintains its position and angle of rotation BE2025 / 5018 15 when, other than gravity, no external forces act on the holder5. Under the influence of an external force, the position of the holder5 is however movable with respect to the5basic element 2. In practice, the friction joint can also occur in combination with one or more flexible zones 9. 10 The holder 5 is provided with means for pressing 10 the holder 5 against the object or surface to be measured. In this case, these means for pressing 10 comprise several permanent magnets 10, which are provided for this purpose 15 along a circumferential edge of the holder 5. The three magnets 10 or three pairs of magnets form a regular triangle on an imaginary circle, with each vertex of the triangle at an angle of 120 degrees to one another. Alternatively, for example, two magnets 10 can also be placed at a certain distance 20 from each other on an imaginary line. Various variations are possible. The number of magnets 10 is unlimited in practice. Alternatively, these means of pressing10 may also comprise one or more electromagnets or one or more means of creating a vacuum, such as, for example, one or more suction cups. These means of creating a vacuum can be useful when the object or surface to be measured is non-magnetic.30 BE2025 / 5018 16Negative pressure here must be interpreted as a pressure that is lower than atmospheric pressure. These means of pressing10 ensure sufficient contact pressure between the measuring surface of the measuring sensor or5 the measuring device8 and the object or surface to be measured. Figure 2 concerns a side view of the device1, in which it can be seen that the base element2 in this example10 is designed to be telescopic. In this case, the base element comprises two telescopic segments, but in practice this number is unlimited. Compared to Figure 1, the two telescopic segments15 2A,2B are partially separated, so that the total length of the base element in Figure 2 is greater than in Figure 1. The telescopic segments 2A, 2B are furthermore provided with locking devices to be able to block the positioning of segments 2A, 2B relative to each other at the desired length. In this example, the locking devices are designed as a pin located on the open segment 2A and corresponding holes provided for this purpose in the longitudinal direction of the other segment.2B, one another in such a way that the movement of the segments 2A, 2B relative to each other is blocked when the pin of one segment 2A is inserted into a hole 12 of the other segment 2Bis. The locking devices 11 can naturally be implemented in many different ways, for example by means of a clamping ring or the like. Figure 3 shows an alternative design in which not only a flexible zone 9 is provided between 5 the first hinge 4 and the holder 5, but also a second flexible zone 9 is provided between the base element 2 and the first hinge 4. In this case, the telescopic segment 2B connected to the first hinge is provided with the second flexible zone 9' so that an angular twist or rotation is possible between the telescopic segment 2A held by the user 7 in use and the holder 5. Alternatively, it may be that only a bend or only a rotation is possible. The flexibility coefficient or compliance of the total device 1 is equal to seven mm / N in this example of Figure 3. In practice, this value lies between 20one and ten mm / N, one and ten mm / N inclusive. Alternatively, the flexibility coefficient of compliance of the total aid1, including measuring sensor or measuring device8, may be between one and ten mm / N, one and ten mm / N inclusive.25 This range of flexibility coefficient of compliance ensures that the angle or rotation between the holder5 and the base element2 is easy for the user7 to vary. In the example shown, muscle force30 of the user7 is sufficient, but in other versions this can be done BE2025 / 5018 18 with the aid of an actuator operated by the user7. Such an actuator can, for example, be hydraulically, pneumatically, mechanically or electrically actuated. 5 The second flexible zone9' is in this case made of an elastomer, but in practice this can also be polyurethane, polyvinyl chloride in combination with one or more plasticizers, ethylene-vinyl acetate or a combination of one or more of the aforementioned materials.10 Alternatively or in addition to the materials mentioned above, the second flexible zone9' can also be providedare made of or designed as one or more springs, for example spiral springs, so that an angular displacement / or rotation of the holder 5 relative to the base element 2 is possible. The number of flexible zones 9,9' between the first hinge 4 and the holder 5 and between the first hinge 420 and the base element 2 are in practice unlimited. In Figure 3, the device 1 is pressed against a vertical steel wall 13 with the holder 5, to which a measuring sensor or measuring device 8 is attached, by means of manipulation of the base element 2 by a user not shown 7. The permanent magnets 10 provided for this purpose on the holder 5 ensure sufficient contact pressure between the measuring sensor or measuring device 8 and the steel wall to be measured 13,30, of which, for example, the thickness must be measured locally. BE2025 / 5018 19 The permanent magnets10 can be detached from the surface to be measured 13 by manipulating the basic element 2 using muscle force from the user7. In the case of electromagnets, it can attract and detach5 the electromagnets from the surface to be measured 13occur by switching the electromagnets on or off remotely, or in the case of suction cups by releasing the vacuum. 10 In this figure it can also be seen that the holder5 is equipped with a connection14 for connecting a hose not shown that can transport coupling fluid to the holder5 and with one or more outlet openings in the holder5. Such coupling fluid can then be pumped remotely15 by the user7, under the influence of, for example, a small pump not shown, between the measuring sensor or measuring device 8 and the surface to be measured13. The magnets10 are arranged in such a way that in use20 there is always a small gap between the measuring surface of the measuring sensor8 and the surface to be measured 13, and in such a way that the coupling fluid can flow between the measuring surface and the surface to be measured13. The width of the gap varies from a few micrometers to 25 hundred micrometers. Typically, the width of the gap is in the range of five to five hundred micrometers, depending on the smoothness of the surface, the qualityof the coupling fluid, the pressure and quality of the measuring device8, and so on.30 BE2025 / 5018 20 The width of the gap (in other words, the distance between the measuring surface of the measuring sensor8 and the surface to be measured13) can be adjusted. For example, by means of an adjustment mechanism or by means of various or length-adjustable spacers or the like.5 When using other measuring devices where no coupling fluid is required, this gap is not necessary and the means10 for pressing the holder5 can also be located in a different plane.10 For example, in the case of an EMAT sensor, no coupling fluid is necessary. The distance between the measuring surface of the EMAT sensor and the surface to be measured 13 can amount to up to twenty centimeters. 15 In figures 4 to 6, various examples of operating positions are shown. From these figures it appears that the device 1 according to the invention is capable of performing measurements in all possible planes, namely vertical, horizontal, at an angle, etc., without 20 the user 7 having to change position. InIn these figures 4 to 6, the base element 2 comprises fourteen telescopic segments. The detail of figure 4 as shown in figure 7 makes 25 clear that large deflections of the flexible zones 9, 9' in combination with the opening angle of the first hinge 4 of the device 1 allow even a horizontal plane 13 at height, for example a roof surface 13, to be reached from above and for example 30 a thickness measurement while the user 7 is standing on the ground 15 BE2025 / 5018 21. The angle between the longitudinal line of the holder 5 and the longitudinal line of the base element 2 is almost 180°. In practice, this angle can be even greater than 180°. 5 The device shown in figure 8 comprises the same elements as the variant as described in figures 1 to 7 but the design of the holder 5 is different. The holder 5 as applied in the variant of figure 8 is elongated, with the magnets 10 mainly arranged on a single straight line. In this case, the holder 5 is equipped with six magnets, but in practice this number is unlimited but usually varies between twoten magnets10. As described above, the magnets15 10 in this variant can also be replaced by other means10 for pressing the holder5, such as suction cups. The elongated shape of the holder5 makes this20 variant extremely suitable for measuring curved surfaces such as, for example, a round tube16. When using the variant as shown in figures 1 to 7, the magnets10 or magnet pairs form a25 regular triangle on an imaginary circle. However, three points define a plane, as a result of which a good coupling on a curved or bent surface cannot be guaranteed. 30 BE2025 / 5018 22 Since the magnets10 or magnet pairs of the holder5 in the variant of figure 8 are aligned, there is sufficient contact between the measuring surface of the measuring sensor8 and the surface to be measured13, in this case the tube16. 5 In Figure 9 it is clearly visible that the holder in this variant is provided with two elastic zones17, one and the other such that the holder the curvature of the surface to be measured13, in this case an outer bend of a tube16,can assume. In this example, the holder 5 is partially 10 made of an elastic material. Alternatively, the holder 5 can also be made entirely of an elastic material. The number of elastic zones 17 is unlimited, but usually there are one or two elastic zones 17 present in the holder 5. 15 In Figure 10, the same variant is shown as in Figures 8 and 9, but here measurements are specifically taken on an inner bend of a tube 16. Figures 8 to 10 show how the device according to the invention is excellently 20 capable of also performing accurate measurements on curved or bent surfaces. The variant shown in Figure 11 comprises an extension piece 3 which is made up of several parts, in this case two parts. In this case, a second hinge 18 is provided between a first part 3A and a second part 3B. This variant is extremely suitable for measuring or reaching surfaces facing the sky, such as roof surfaces, the top of pipes or tubes and the like. In this case, the first part 3A BE2025 / 5018 23 is designed to be telescopic and flexible, but this is notnecessary. Alternatively or additionally, the second part 3B can also be designed telescopically and flexibly. In the fourth variant, as shown in Figure 12, the opening angle of the first hinge 4 is limited between a first end stop 19A and a second end stop 19B. In this variant, the smallest enclosed angle α between the longitudinal axis line X-X' of the base element 2 and the longitudinal axis line Y-Y' of the extension 310 is preferably larger when the first end stop 19A is reached than when the second end stop 19B is reached. In this case, the smallest enclosed angle α between the longitudinal axis line X-X' of the base element 2 and the longitudinal axis line Y-Y' of the extension 3 is equal to 45° when the first end stop 19A is reached and equal to 90° when the second end stop 19B is reached. In practice, the smallest included angle α between the longitudinal axis X-X' of the base element and the longitudinal axis Y-Y' of the extension is, for example: - less than or equal to 45° when the first end stop 19A is reached; - less than or equal to 90° when the secondend stop 19B is reached. The opening angle of the first hinge 4 is in practice less than or equal to 180° and preferably equal to 135°. BE2025 / 5018 24 In that case, the longitudinal line X-X' of the base element 2 and the longitudinal line Y-Y' of the extension 3 define a plane in which the extension 3 can tilt in the plane between a first operating position, 5 as shown in Figure 12 and a second operating position as shown in Figure 13. A rotation of the base element 2, whereby the entire assembly of extension 3 and holder 5 are moved past their tilting point, is sufficient to transition from the first operating position to the second operating position or vice versa. The extension 3 will then tilt from the first operating position to the second operating position or vice versa under the influence of gravity. Alternatively, the transition from the first operating position to the second operating position or vice versa can also be actuated, for example by an actuator. In the example as shown in figures 12 and 13, there is also a between the holder 5 and the extension 3.friction joint22 provided. This friction joint22 is in this case a ball joint but can alternatively be another joint or a knee joint. The friction joint 22 ensures that the holder5 can be rotated relative to the extension3 so that a wide range of angles and positions can be achieved.25 The friction joint22 ensures sufficient friction between the holder5 and the extension3 so that the holder5 does not move under the influence of gravity, but can move under the influence of other external forces.30 BE2025 / 5018 25 The operation of the device1 is very simple and becomes clearer using figures 14 to 17. In a first step (a) a measuring sensor or measuring device8 is attached to the holder5 of the device1 (unless it is already present). Subsequently, if necessary, in a second step b) the opening angle of the first hinge 4 is adjusted and locked. 10 If necessary, the base element 2 is brought to the correct length by sliding and then locking one or more telescopic segments 2A, 2B,… of the base element 2. 15Next, the holder is moved in the direction of the surface to be measured13 or close to the surface to be measured13 until the desired measurement location is reached on the surface to be measured1320; this situation is shown in Figure 14, where the holder is moved in the direction of the arrow F, close to the surface to be measured13. In practice, the invention also works in the reverse direction. 25 Close here refers to a distance of one millimeter to a few tens of centimeters. In a subsequent step (d), the holder 5 is brought into contact with the surface to be measured 13 such that a point of contact 30 BE2025 / 5018 26 20 is created between the holder 5 and the surface to be measured 13. At that moment, an angle β exists between the plane K formed by the measuring surface of the measuring sensor 8 and the plane L formed by the surface to be measured 13. This is shown in Figure 15, where angle β is approximately 45°. However, this angle β can vary significantly in this phase, for example between 5° and 90°. 10 In a subsequent step (the base element is manipulated, pushed away, repelled, or extended such that a moment Mis created around the point of contact 20. The point of contact 20 shifts only minimally or not at all with respect to the surface to be measured 13 thanks to one or more friction zones 2115 of the holder 5. Thanks to these friction zones 21, a moment Minus is indeed created at the point of contact 20 when the base element 2 is moved further in the 20 direction of the arrow F, under the influence of an attractive force caused by the magnets 10 or other means 10 for pressing the holder 5. This causes the measuring surface of the measuring sensor 8 to be brought to the surface to be measured 13 under the influence of the magnets 10 or other means 10 for pressing the holder 5. This step is shown in Figure 16.25. The moment M can only be created if sufficient attractive force is present as a result of the means. 10 for pressing and / or sufficient friction force is created at the point of contact20. Without at least one of these 30 forces, the measuring sensor 8 would slide along the surface to be measured BE2025 / 5018 27 surface13, whereby no effective coupling is established. At the point of contact20, as it were, aA pivot point is created around which the holder 5 can pivot. The attractive force of the means of pressing 10 and / or external forces, for example a 5 manual manipulation of the base element 2, cause a rotating movement of the holder 5 around the point of contact 20 whereby the surface of the measuring sensor 8 to be measured is pressed as well as possible against the surface to be measured 13. 10 The aforementioned friction zones 21 can be provided locally or entirely around the perimeter edge of the holder 5. Subsequently, the angle β between the plane Ken and the plane L, as shown in Figure 17, will be approximately equal to 0°; in 15 that case the measuring sensor 8 is coupled with the surface to be measured 13. Optionally, another step (f) follows in which coupling fluid 20 is injected between the plane Ken and the surface to be measured 13. This step (f), which only takes place after connection, has the advantage that the measuring surface of the measuring sensor8 does not wear out. Thanks to the configuration25 of the holder5 and the means10, as described above, the measuring surface does not come into direct contact with the surface to be measured13.As a result, measuring sensors8 last much longer than with the known measuring sticks or aids1 for holding and positioning a measuring sensor or measuring device8 against an object or surface to be measured13. In the latter, prior to BE2025 / 5018 28 the coupling fluid is first applied to the surface to be measured13 and subsequently the measuring sensor8 is pressed onto the surface to be measured13, resulting in wear of the measuring sensor. 5 It goes without saying that the magnets10 only have an effect when the surface to be measured13 is magnetic. For non-magnetic surfaces13, the other means 10 for pressing the holder5, for example suction cups, can prove their worth.10 The aid and method according to the invention therefore provide for a self-aligning holder5 and by extension a self-aligning aid. The aid according to the invention can reach all possible directions and surfaces.15 In practice, the compliance or flexibility is the coefficient of all flexible zones9 added up such that the holder5 does not change position.under the influence of gravity but at the same time the sum of the attractive forces of the means 10 for pressing the holder 5, for example the sum of the magnetic forces, is large enough to overcome the sum of the compliances or flexibility coefficients of flexible zones 9 when the device is in step 25. However, the attractive forces of the means 10 must not be too large, such that the holder 5 can also still be easily detached (pulled away) from the surface to be measured 13. 30 BE2025 / 5018 29 In summary: ∑forces needed to bend flexible zones 9<∑attractive forces of the means 10 of the holder 5. For reasons of clarity, only a part of the basic element 2 is shown in figures 1 to 3 and 5 7 to 17. The invention also relates to an aid1 in which no first hinge4 is provided between the10 base element2 and the extension3, but in which the base element2 is directly coupled to the extension3 and in which the bending or rotation of the base element2 with respect to the holder5 is possibleis made by one or more flexible zones9,9' which are provided for that purpose between the base element2 and the holder5. The present invention is by no means limited to the example described and