Laser measuring device for measuring width and length of bridge crack

Abstract

The invention relates to a laser measuring device for measuring the width and length of a bridge crack, and belongs to the technical field of bridge detection, and the laser measuring device comprises a walking assembly, a steering assembly, an adjusting assembly, a laser range finder and a sensing assembly. Wherein the walking assembly is used for providing power for the laser measuring device to walk on a bridge; the steering assembly is arranged on a walking base in the walking assembly and used for providing power for the laser range finder to rotate in the vertical direction. The adjusting assembly is arranged on a steering table in the steering assembly, and independent movement in the vertical direction and the horizontal direction is provided for the laser range finder through an adjusting plate. The sensing assembly is arranged on the walking assembly and corrects the walking direction of the whole laser measuring device, and the situation that a complex visual system is needed to complete crack width and length measurement work is avoided. According to the method, the dependence on a complex visual identification algorithm is abandoned, and the problems of instable identification, precision reduction and even failure in the prior art are fundamentally eliminated.

Description

Technical Field

[0001] This application relates to the technical field of bridge inspection, and in particular to a laser measuring device for measuring the width and length of cracks in bridges. Background Technology

[0002] During the long-term service of bridges, cracks often appear on the bridge surface due to factors such as load, material aging, and environmental erosion. The appearance of these cracks not only affects the appearance of the bridge, but may also threaten its structural safety. Therefore, regular and accurate monitoring and assessment of cracks is particularly important.

[0003] In recent years, with the development of detection technology, some automated or semi-automated detection equipment has begun to be applied to bridge crack detection. For example, image recognition-based vision inspection systems can acquire crack images through cameras and then extract crack width and length information through image processing algorithms. However, vision systems usually require complex algorithms and high computing resources, placing high demands on hardware. At the same time, when the crack is long, in order to ensure high resolution, it is necessary to identify the crack in different regions, making it difficult to achieve real-time updates of the equipment's movement path.

[0004] Therefore, there is an urgent need for a new laser measurement device. Summary of the Invention

[0005] To address the problem that existing image recognition-based laser measurement devices cannot update their travel path in a timely manner when measuring large and long cracks on bridges, this application provides a laser measurement device for measuring the width and length of bridge cracks.

[0006] The laser measuring device for measuring the width and length of cracks in bridges provided in this application adopts the following technical solution: A laser measuring device for measuring the width and length of cracks in bridges includes: A walking assembly, including a walking seat and for walking on a bridge; A steering assembly is mounted on the travel seat and includes a steering platform, the axis of rotation of which is perpendicular to the upper surface of the bridge. An adjustment assembly is provided on the turntable and includes an adjustment plate, the adjustment plate being movable independently in a vertical direction and a horizontal direction, the vertical direction being perpendicular to the upper surface of the bridge and the horizontal direction being parallel to the upper surface of the bridge; A laser rangefinder is mounted on the adjustment plate and used to measure the width and length of cracks on the bridge; A control component is disposed inside the walking seat and electrically connected to the walking component, the steering component, the adjustment component, and the laser rangefinder; The sensing component is mounted on the traveling seat and includes a sensing probe, a sensing shaft, and an angle sensor. The sensing shaft is rotatably connected to the traveling seat, and the angle sensor is connected to the traveling seat and electrically connected to the control component. The angle sensor is used to sense the angle of rotation of the sensing shaft. One end of the sensing probe is connected to the sensing shaft, and the other end is inserted into the bridge crack and abuts against the inner wall of the crack. As the sensing probe moves along the inner wall of the bridge crack, the angle of the rotating sensing shaft will adjust the walking direction of the walking component through the control component.

[0007] By adopting the above technical solution, an independent sensing component is installed. Its sensing probe extends into the inner wall of the crack and oscillates along the crack's path, driving the sensing shaft to rotate. An angle sensor detects this rotation angle in real time and feeds it back to the control component. Based on this angle signal, the control component controls the walking direction of the walking component in real time, enabling the entire device to automatically and accurately move along the crack trajectory. This solution eliminates the need for a complex and environmentally sensitive visual recognition system, achieving adaptive path tracking and fundamentally solving the problem of path tracking lag in existing visual inspection methods for measuring long-distance, curved cracks.

[0008] Optionally, the sensing component further includes a sensing drive shaft, one end of which is connected to the sensing shaft, and the other end has a square hole. The sensing probe has a square portion, which passes through the square hole. The sensing probe can move vertically relative to the sensing drive shaft.

[0009] By adopting the above technical solution, the sensing probe slides with the square hole of the sensing drive shaft through the square part. On the one hand, this ensures that the sensing probe can transmit the lateral thrust of the crack inner wall it receives without loss to the rotation of the sensing drive shaft and sensing shaft, avoiding the distortion of the angle signal caused by relative rotation and ensuring the accuracy of the path tracking signal. On the other hand, it allows the sensing probe to slide relative to each other in the vertical direction, so that it can adapt to the changes in crack depth and avoid getting stuck or bearing excessive longitudinal bending moment due to uneven crack bottom. This improves the device's passability to irregular crack terrain and the service life of the sensing components.

[0010] Optionally, the sensing component further includes a limiting ring, which is sleeved on the square portion of the sensing probe and located on both sides of the end of the sensing drive shaft.

[0011] By adopting the above technical solution, the limiting rings set on the square part of the sensing probe are located on both sides of the square hole of the sensing drive shaft. This structure can effectively limit the sliding stroke of the sensing probe relative to the sensing drive shaft in the vertical direction, prevent the sensing probe from completely dislodging from the square hole during vibration or rapid movement, ensure the structural connection reliability and stability of the sensing component during operation, and reduce the failure rate.

[0012] Optionally, the sensing component further includes a first gear and a second gear, the first gear being sleeved on the outside of the sensing shaft, and the second gear being sleeved on the input end of the angle sensor, with the first gear and the second gear being engaged.

[0013] By adopting the above technical solution, the rotation of the sensing shaft is accurately transmitted to the input end of the angle sensor through the meshing transmission of the first and second gears. Gear transmission has the advantages of stable transmission ratio, high efficiency, and compact structure. It can convert mechanical rotation angle into electrical signal without hysteresis and with high fidelity, ensuring the accuracy and reliability of the angle measurement process and providing accurate raw data for the subsequent precise control of the travel direction.

[0014] Optionally, the sensing component further includes a rotating seat, which is disposed on the traveling seat. The rotating seat has a rotating hole, and the sensing shaft passes through the rotating hole. The first gear is located outside the rotating hole.

[0015] By adopting the above technical solution, the rotating base provides a stable and reliable rotational support for the sensing shaft, ensuring that its rotation axis position is fixed. The first gear is positioned outside the rotating hole, facilitating gear installation, maintenance, and adjustment for meshing with the second gear. This structural layout is reasonable, making the mechanical transmission part of the sensing component structurally stable and operating smoothly, reducing measurement errors caused by unstable support.

[0016] Optionally, the sensing component further includes a fixed bracket, which is disposed on the rotating base, and the angle sensor is disposed on the top of the fixed bracket.

[0017] By adopting the above technical solution, the fixed bracket securely mounts the angle sensor on the rotating base, providing a precise installation reference for the angle sensor. This ensures that the second gear and the first gear maintain a stable and precise meshing center distance, avoiding poor gear meshing or signal noise caused by sensor vibration, and further guaranteeing the accuracy and stability of the angle sensing signal.

[0018] Optionally, the sensing component further includes a sensing probe, which is fixed to the bottom end of the sensing probe by a threaded connection, and the sensing probe is made of wear-resistant metal.

[0019] By adopting the above technical solution, a replaceable wear-resistant metal induction probe is connected to the bottom of the induction probe via a threaded connection. As the component that directly contacts and withstands friction with the inner wall of the rough crack, the wear-resistant properties of the induction probe body significantly reduce the wear of the induction probe body. When the probe wears out, only the probe needs to be replaced, which significantly extends the service life of the core component, the induction probe, and reduces maintenance costs and replacement frequency.

[0020] Optionally, the outer surface of the sensing probe is spherical.

[0021] By adopting the above technical solution, the spherical sensing probe can interact with the inner wall of the crack in a point-contact manner. This design greatly reduces the frictional resistance when the probe moves within the crack, making the device move more smoothly, reducing the load on the walking components, and also enabling the sensing probe to respond more sensitively to subtle changes in direction, thus improving the precision and sensitivity of path tracking.

[0022] Optionally, the projection of the sensing probe within the crack is located in front of the projection of the laser rangefinder within the crack.

[0023] By adopting the above technical solution, the spatial projection of the sensing probe is positioned in front of the laser rangefinder. This allows the sensing component to "pre-detect," meaning it senses changes in the crack's orientation before the laser rangefinder. Upon receiving the angle change signal, the control component has sufficient time to calculate and adjust its direction, ensuring that when the laser rangefinder reaches the position, its optical path is already aligned with the crack. This achieves the effect of "adjustment before measurement," guaranteeing continuous alignment of the laser optical path during continuous measurement and avoiding measurement interruptions or data loss.

[0024] Optionally, the projection of the sensing probe within the crack is located in front of the projection of the laser rangefinder within the crack.

[0025] By adopting the above technical solution and adjusting the movement of the components, it is ensured that the measuring spot of the laser rangefinder can completely cover the crack to be measured on the bridge surface. This guarantees that the laser rangefinder can perform a scanning measurement of the entire crack section during a single movement. Combined with the recording of the movement distance, the total length of the crack can be accurately calculated, and the width data of each point along the path can be obtained, realizing comprehensive and efficient automated measurement of the crack's geometric dimensions.

[0026] In summary, this application includes at least one of the following beneficial technical effects: The crack's trajectory is sensed through direct physical contact between a sensing probe and the crack's inner wall. Changes in trajectory are then directly and without delay converted into electrical signals for the angle sensor via gears and other transmission mechanisms. This method completely eliminates the reliance on complex visual recognition algorithms, fundamentally removing the problems of instability, decreased accuracy, and even failure associated with existing technologies. It not only reduces the need for high-performance processors but also achieves stable and real-time tracking of crack trajectories in complex outdoor environments.

[0027] By spatially positioning the sensing probes in front of the laser rangefinder, changes in the crack's orientation are detected in advance and converted into control commands, driving the walking and adjustment components to complete pose adjustments before the laser rangefinder reaches the measurement point. This design ensures that the laser rangefinder remains continuously and directly aligned with the crack throughout the entire measurement process, achieving uninterrupted measurement and complete data collection.

[0028] This device breaks down complex automated detection tasks into modular functional components such as walking, steering, sensing, and measurement. The replaceable, wear-resistant probes at the ends of the sensing probes and the standardized design of the transmission mechanism make key vulnerable components easy to replace and maintain, extending the overall lifespan of the machine. The entire system requires no complex calibration procedures or expensive environmental control requirements, and has low dependence on the professional skills of operators. Attached Figure Description

[0029] Figure 1 This is an isometric schematic diagram of the laser measuring device for measuring the width and length of cracks in bridges provided in this application; Figure 2 yes Figure 1 Front view; Figure 3 yes Figure 1 The left view; Figure 4 yes Figure 3 A magnified view of a section at point A in the middle; Figure 5 yes Figure 1 Top view; Figure 6 yes Figure 1 A schematic diagram of the structure after the sensing components are hidden and rotated by an angle; Figure 7 This is a schematic diagram of the sensing component in this application.

[0030] In the picture: 1. Walking assembly; 2. Steering assembly; 3. Adjustment assembly; 4. Laser rangefinder; 5. Sensor assembly; 11. Walking seat; 12. Walking wheels; 13. Walking drive unit; 21. Steering platform; 22. Steering seat; 23. Steering drive unit; 31. Adjustment plate; 32. First adjustment driver; 33. Second adjustment driver; 51. Sensing probe; 52. Sensing shaft; 53. Angle sensor; 54. Sensing drive shaft; 55. Limiting ring; 56. First gear; 57. Second gear; 58. Rotating seat; 59. Sensing probe. Detailed Implementation

[0031] The following is in conjunction with the appendix Figures 1-7 This application will be described in further detail.

[0032] This application discloses a laser measuring device for measuring the width and length of cracks in bridges.

[0033] refer to Figure 1 A laser measuring device for measuring the width and length of cracks in bridges includes a walking assembly 1, a steering assembly 2, an adjustment assembly 3, a laser rangefinder 4, and a sensing assembly 5. The walking assembly 1 provides power for the laser measuring device to move on the bridge; the steering assembly 2 is mounted on a walking seat 11 within the walking assembly 1 and provides power for the laser rangefinder 4 to rotate vertically; the adjustment assembly 3 is mounted on a steering platform 21 within the steering assembly 2 and, with the aid of an adjustment plate 31, provides independent vertical and horizontal movement for the laser rangefinder 4; the sensing assembly 5 is mounted on the walking assembly 1 and corrects the overall direction of movement of the laser measuring device, thus avoiding the need for a complex vision system to measure the width and length of cracks.

[0034] refer to Figure 4 and Figure 7The sensing component 5 includes a sensing probe 51, a sensing drive shaft 54, a sensing rotating shaft 52, a rotating seat 58, and an angle sensor 53. The rotating seat 58 is mounted on the traveling seat 11 and has a rotating hole. The sensing rotating shaft 52 is cylindrical and rotatably mounted within the rotating hole. The axis of the sensing rotating shaft 52 is perpendicular to the surface of the traveling seat 11 (and also perpendicular to the surface of the bridge). The axis of the sensing probe 51 is perpendicular to the bridge surface, and its bottom end penetrates into the crack. The sensing drive shaft 54 ​​is positioned between the sensing probe 51 and the sensing rotating shaft 52. The sensing drive shaft 54 ​​and the sensing rotating shaft 52 are fixedly connected and rotate synchronously. The sensing probe 51 is slidably connected to the sensing drive shaft 54. This sliding connection ensures that the sensing probe 51 remains within the crack, preventing it from experiencing excessive vertical pressure due to varying crack depths, thus reducing its lifespan. Meanwhile, an angle sensor 53 is mounted on the rotating base 58. The angle sensor 53 detects the angle rotated by the sensing shaft 52 and transmits this angle to the control component. The control component uses an internal algorithm to determine the angle the walking component 1 should rotate, ensuring that the laser rangefinder 4 always emits laser light into the crack within the working space. Since the sensing probe 51 remains in contact with the inner wall of the crack and there is no relative rotation between the sensing probe 51 and the sensing drive shaft 54, when the crack bends, the inner wall of the crack pushes the sensing probe 51, causing it to move. This manifests as a swing at the end of the sensing drive shaft 54 ​​that contacts the sensing probe 51. This swing causes rotation at the other end of the sensing drive shaft 54, ultimately resulting in the rotation of the sensing shaft 52. This rotation angle adjusts the trajectory of the entire laser measuring device during its movement, ensuring that the laser measuring device always travels within the effective detection area. Without using a vision system, the width and length of longer cracks on bridges can be detected efficiently.

[0035] refer to Figure 4 and Figure 7 Since the bottom end of the sensing probe 51 is always in contact with the inner wall of the crack, in order to improve the service life of the sensing probe 51 and avoid frequent replacements, a sensing probe 59 is installed at the bottom end of the sensing probe 51. The sensing probe 59 is made of wear-resistant metal and is fixed to the bottom end of the sensing probe 51 by a threaded connection. The outer surface of the sensing probe 59 is spherical, which reduces the resistance encountered during movement. At the same time, by setting the sensing probe 59, the wear of the sensing probe 51 can be greatly reduced, thus improving the service life of the sensing probe 51.

[0036] refer to Figure 4 and Figure 7Since the sensing probe 51 and the sensing drive shaft 54 ​​are slidably connected, a square hole is provided at the end of the sensing drive shaft 54 ​​to prevent relative rotation between them. Simultaneously, a portion of the sensing probe 51 is designed as a square section, with a cuboid shape. The square section passes through the square hole. This combination of the square section and the square hole prevents relative rotation between the sensing probe 51 and the sensing drive shaft 54, ensuring that the movement between them is only vertical.

[0037] Meanwhile, to prevent the sensing probe 51 from detaching from the sensing drive shaft 54, two limiting rings 55 are provided on the square portion of the sensing probe 51. The limiting rings 55 are made of rubber, and are fitted over the outside of the sensing probe 51. One limiting ring 55 is located above the end of the sensing drive shaft 54, and the other is located below the end of the sensing drive shaft 54. The limiting rings 55 do not enter the square hole, thus limiting the range of movement of the sensing probe 51 relative to the sensing drive shaft 54, thereby preventing the sensing probe 51 from completely detaching from the sensing drive shaft 54.

[0038] refer to Figure 4 and Figure 7 To ensure stable transmission of the rotation of the sensing shaft 52 to the angle sensor 53, a first gear 56 is fitted onto the sensing shaft 52, and a second gear 57 is fitted onto the input end of the angle sensor 53. The first gear 56 and the second gear 57 are meshed. With this configuration, by determining the module of the first gear 56 and the second gear 57, the angle rotated by the first gear 56 can be converted into the angle rotated by the second gear 57, and thus the required rotation angle of the walking component 1 can be calculated within the control assembly.

[0039] To maintain a stable meshing relationship between the first gear 56 and the second gear 57, a fixed bracket is provided on the rotating base 58. The fixed bracket is fixed to the rotating base 58 by bolts, and an angle sensor 53 is connected to the top of the fixed bracket. The fixed bracket allows the angle sensor 53 and the second gear 57 to be as close as possible to the first gear 56, which is beneficial to the stability of force transmission between the gears.

[0040] refer to Figure 1 and Figure 6 The traveling assembly 1 includes a traveling seat 11, traveling wheels 12, and a traveling drive 13. The traveling wheels 12 are located at the bottom of the traveling seat 11, and the traveling drive 13 is located inside the traveling seat 11. The steering assembly 2 is mounted on the traveling seat 11 and located in the middle of the traveling seat 11, which reduces the impact on the center of gravity of the traveling assembly 1.

[0041] refer to Figure 1 and Figure 6The steering assembly 2 includes a steering platform 21, a steering seat 22, and a steering drive 23. The steering seat 22 and the steering drive 23 are both located inside the travel seat 11. The steering platform 21 is rotatably mounted on the steering seat 22 and rotates by means of the steering drive. The upper surfaces of the steering platform 21 and the travel seat 11 are flush.

[0042] refer to Figure 1 and Figure 6 The adjustment assembly 3 includes an adjustment plate 31, a first adjustment driver 32, and a second adjustment driver 33. The first adjustment driver 32 is mounted on the turntable 21 and can be selected as a screw slide transmission method, and is used to provide vertical lifting of the adjustment plate 31. The second adjustment driver 33 is located on the first adjustment driver 32 and is used to provide horizontal movement. The second adjustment driver 33 can be selected as a combination of an electric push rod and a slider. The slider slides on the slide table, and the push end of the electric push rod is connected to the slider, thereby realizing the reciprocating linear movement of the slider on the slide table. At the same time, the adjustment plate 31 is fixed to the slider by bolt connection.

[0043] It should be noted that since the walking component 1, steering component 2, adjustment component 3 and control component are all prior art and are not strongly related to the inventive point of this application, they will not be described in detail. Those skilled in the art can fully understand and reproduce the structure of each of the above components.

[0044] The principle of the laser measuring device for measuring the width and length of bridge cracks in this embodiment is as follows: Before the device starts working, the operator places the sensing probe 51 of the sensing component 5 into the starting end of the crack. Driven by the walking component 1, the device begins to move along the initial direction. The sensing probe 59 remains inside the crack, with its side in contact with the inner wall of the crack.

[0045] When the crack bends, the inner wall of the crack exerts a vertical or oblique thrust on the probe traveling in the direction of travel. This thrust forces the sensing probe 51 to produce a lateral displacement. Since the square part of the sensing probe 51 is stuck in the square hole of the sensing drive shaft 54, the two cannot rotate relative to each other. Therefore, the lateral displacement of the probe is directly converted into the oscillation of the end of the sensing drive shaft 54. The other end of the sensing drive shaft 54 ​​is fixed to the sensing rotating shaft 52, thereby driving the sensing rotating shaft 52 to rotate precisely within the rotating seat 58. The rotation angle of the sensing rotating shaft 52 is transmitted to the angle sensor 53 without lag through the meshing of the first gear 56 sleeved on it and the second gear 57 sleeved on the input shaft of the angle sensor 53. The angle sensor 53 detects this angle change in real time and converts it into a corresponding electrical signal, which is sent to the control component. The control component has a preset control algorithm. After receiving the signal from the angle sensor 53, the algorithm calculates it as the actual deviation angle of the crack relative to the current direction of travel of the device. Subsequently, the algorithm immediately generates a corresponding control command. The goal of this command is to adjust the walking direction of the walking component 1 so that the overall forward direction of the device is realigned with the actual direction of the crack, thereby ensuring that the sensing probe 59 returns to the center of the crack and is in a position of force balance.

[0046] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A laser measuring device for measuring the width and length of a bridge crack, characterized by, The utility model relates to a bridge crack detection device, including: Walking assembly (1) including walking seat (11) and is used in walking on bridge; Steering assembly (2) sets up on walking seat (11) and includes steering platform (21), and the rotation axis of steering platform (21) is perpendicular to the upper surface of bridge; Adjustment assembly (3) sets up on steering platform (21) and includes adjusting plate (31), and adjusting plate (31) can move independently along vertical direction and horizontal direction, and vertical direction is perpendicular to the upper surface of bridge, and horizontal direction is parallel to the upper surface of bridge; Laser range finder (4) sets up on adjusting plate (31) and is used for measuring the width and length of bridge crack; Control assembly sets up in the inside of walking seat (11) and is electrically connected walking assembly (1), steering assembly (2), adjustment assembly (3) and laser range finder (4); Induction assembly (5) sets up on walking seat (11) and includes induction probe (51), induction rotating shaft (52) and angle sensor (53), and induction rotating shaft (52) is rotatably connected on walking seat (11), and angle sensor (53) is connected on walking seat (11) and is electrically connected control assembly, and angle sensor (53) is used for sensing the angle of rotation of induction rotating shaft (52), and one end of induction probe (51) is connected on induction rotating shaft (52), and the other end is penetrated into bridge crack and is abutted on the inner wall in crack; When induction probe (51) moves along the inner wall of bridge crack, the angle of rotation of induction rotating shaft (52) is adjusted to the walking direction of walking assembly (1) through control assembly.

2. The laser measuring device for measuring the crack width and length of a bridge according to claim 1, characterized in that: The induction assembly (5) further includes an induction transmission shaft (54), one end of the induction transmission shaft (54) is connected to the induction rotating shaft (52), and the other end is provided with a square hole, the induction probe (51) has a square part, the square part of the induction probe (51) is arranged in the square hole, and the induction probe (51) can move along the vertical direction relative to the induction transmission shaft (54).

3. The laser measuring device for measuring the crack width and length of a bridge according to claim 2, characterized in that: The induction assembly (5) further includes a limiting ring (55), the limiting ring (55) is sleeved on the square part of the induction probe (51) and located on both sides of the end part of the induction transmission shaft (54).

4. The laser measuring device for measuring the crack width and length of a bridge according to claim 2, characterized in that: The induction assembly (5) further includes a first gear (56) and a second gear (57), the first gear (56) is sleeved on the outside of the induction rotating shaft (52), the second gear (57) is sleeved on the input end of the angle sensor (53), and the first gear (56) and the second gear (57) are engaged.

5. The laser measuring device for measuring the crack width and length of a bridge according to claim 4, characterized in that: The induction assembly (5) further includes a rotating seat (58), the rotating seat (58) is arranged on the walking seat (11), a rotating hole is formed in the rotating seat (58), the induction rotating shaft (52) is arranged in the rotating hole, the first gear (56) is located outside the rotating hole.

6. The laser measuring device for measuring the crack width and length of a bridge according to claim 5, characterized in that: The inductive assembly (5) further comprises a fixing support arranged on the rotating base (58), and the angle sensor (53) is arranged on the top of the fixing support.

7. The laser measuring device for measuring the crack width and length of a bridge according to claim 1, wherein: The inductive assembly (5) further comprises an inductive probe (59) fixed in a threaded connection mode at the bottom end of the inductive probe (51), and the inductive probe (59) is made of wear-resistant metal.

8. The laser measuring device for measuring the crack width and length of a bridge according to claim 7, characterized in that: The outer surface of the inductive probe (59) is spherical.

9. The laser measuring device for measuring the crack width and length of a bridge according to any one of claims 1-8, characterized in that: The projection of the inductive probe (51) in the crack is located in front of the projection of the laser range finder (4) in the crack.

10. The laser measuring device for measuring the crack width and length of a bridge according to claim 9, characterized in that: The crack on the bridge is located in the projection of the laser range finder (4) on the surface of the bridge during the movement of the laser range finder (4) by means of the adjusting plate (31).

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