A method for measuring the diameter of underground rainwater and sewage pipes

Abstract

The present invention relates to a method for measuring the diameter of underground rainwater and sewage pipes in the field of measurement technology. Step 1: Place a measuring unit in the inner cavity of the underground rainwater and sewage pipe to be measured. The measuring unit comprises a plurality of first laser ranging modules arranged along the X-axis plane with a zero point as the center and emitting laser light outward, and a plurality of second laser ranging modules arranged along the Y-axis plane with a zero point as the center and emitting laser light outward, wherein the pitch circle diameters of the first laser ranging modules and the second laser ranging modules are the same. The present invention employs the principle of spatial circle fitting to analyze and process the collected data, thereby improving the reliability of the results.

Description

Technical Field

[0001] The present invention relates to the field of measurement technology, in particular to a method for measuring the diameter of an underground rainwater and sewage pipe. Background Art

[0002] As cities continue to grow in size, underground pipelines, as a major component of municipal engineering, are becoming increasingly important. The requirements for pipeline measurement in the construction of new and renovation of old underground pipelines are becoming increasingly higher. The accuracy of the measurement data directly affects the rationality of the design and can avoid design changes, repeated construction, and pipeline safety accidents in the later stages.

[0003] For underground rainwater and sewage pipes, the pipe diameter is particularly important among its many parameters and is difficult to obtain. To obtain accurate rainwater and sewage pipe diameter data, traditional methods usually use contact measurement, that is, manually measuring the pipe diameter directly with a ruler, or measuring the distance between the bottom and top of the pipe and the ground, and using the distance difference to obtain the pipe diameter. For rainwater and sewage wells, a large amount of dangerous gases usually accumulate in the manholes, and the oxygen is thin. It is very dangerous for people to enter rashly. In addition, sewage or silt is deposited at the bottom of some rainwater and sewage pipes. The existing measurement methods are difficult to operate, the measurement results are uncontrollable, and the reliability is low, which cannot meet the needs of normal pipeline measurement operations. At present, the more convenient methods include using laser scanners or total stations to collect pipe wall point clouds and fit the pipe diameter. This method is complicated to operate and has low efficiency. The pipe diameter is obtained by using QV equipment to collect pipe images and distances for binarization processing. Although the operation is simple, it has high requirements for the working environment and the reliability of the results is low.

[0004] Currently, a Chinese patent application numbered 201520481867.3, published on December 16, 2015, discloses a device for measuring the internal diameter of underground pipelines in ports. The device comprises a vertical measuring device and a horizontal connecting device fixedly connected thereto. Three mutually perpendicular lasers are disposed at the ends of the horizontal connecting device. The three laser distance values ​​are manually recorded, and the pipe diameter is calculated using the triangle circumscribed circle method. However, the device has the following drawbacks: 1. During measurement, the vertical measuring device must be manually held in a vertical position using a circular level bubble, which not only requires high operator skill but also has low precision, affecting the measurement results. 2. Using this device, it is difficult to ensure that the planes on which the three lasers lie are parallel to the radial plane of the pipeline, resulting in errors in the measurement data and, in turn, influencing the measurement results. 3. The use of manual recording and calculation of data reduces on-site operation efficiency. 4. The lasers used lack a control unit, and asynchronous ranging can easily lead to large ranging errors or even mistakes. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for measuring the diameter of underground rainwater and sewage pipes in order to solve the above problems.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0007] A method for measuring the diameter of an underground rainwater and sewage pipe comprises the following steps:

[0008] Step 1: Place the measuring unit in the inner cavity of the underground rainwater and sewage pipe to be measured, wherein the measuring unit has a plurality of first laser ranging modules arranged along the X-axis plane with the zero point as the center and emitting lasers outward, and a plurality of second laser ranging modules arranged along the Y-axis plane with the zero point as the center and emitting lasers outward, and the pitch circle diameter of the first laser ranging module is the same as the pitch circle diameter of the second laser ranging module;

[0009] Step 2: Turn on the first laser ranging module and the second laser ranging module, and adjust the measurement unit posture so that the Y-axis plane is parallel to the axial plane of the underground rainwater and sewage pipe to be measured, and at the same time, all the first laser ranging modules and all the second laser ranging modules simultaneously measure the distance;

[0010] Step 3: The vertical plane formed by the straight line formed by the light spots emitted by the multiple second laser ranging modules on the wall of the underground rainwater and sewage pipe to be measured is set as the projection plane. All measuring points are projected onto the projection plane, which can effectively eliminate the longitudinal tilt error caused by the arbitrary posture of the measuring part; solve the following equation Get the projected coordinates p of the measuring point ti (x ti ,y ti , z ti );

[0011] Step 4: Use space circle fitting to fit and obtain the two parameters of the center O (x0, y0, z0) and radius r of the fitting space circle.

[0012] Preferably, one of the first laser ranging module or the second laser ranging module is located on the Z axis.

[0013] Preferably, the method for adjusting the posture of the measuring part is:

[0014] According to the geometric relationship of the laser ranging module, the light spot position p of the laser emitted by the laser ranging module located on the Z axis on the wall of the underground rainwater and sewage pipe to be measured is calculated. i Coordinate (x i ,y i , z i );

[0015] Any two second laser ranging modules emit lasers at light points p on the inner wall of the underground rainwater and sewage pipe to be measured. i-1 、p i+1 , under ideal conditions p i-1 、p i 、pi+1 Collinear, p i-1 and p i+1 The equation of a line between two points is expressed as

[0016] Among them, p i The intercept distance from the point to the wall of the underground sewage pipe to be measured is d, which is used to determine the posture of the measuring part. d is expressed as: If d>m, the measuring part needs to rotate and adjust its posture until d≤m;

[0017] Among them, the intercept error m is composed of measurement error and pipeline manufacturing error, which can be solved by the error propagation law;

[0018] The perpendicular plane equation is derived from the straight line equation, and the perpendicular plane equation is the required constructed projection surface; wherein the perpendicular plane equation is: ax+by+cz-1=0.

[0019] Preferably, the RANSAC algorithm is used to filter out the erroneous points in the projected coordinates of the measurement points in step 3;

[0020] Use the minimum model of space circle fitting to fit, get the two parameters of the center O (x0, y0, z0) and radius r of the random fitting space circle, and calculate the difference between the distance from all points to the center and the radius μ i , and compare it with the threshold T to screen out the qualified projection point coordinates;

[0021] When the number of qualified projection points q meets the set minimum number Q, calculate:

[0022] According to the straight line passing through the center of the circle and the midpoint of the chord in the space circle is perpendicular to the chord, the polynomial is obtained: Δx i,i+1 x0+Δy i,i+1 y0+Δz i,i+1 z0-l i =0;

[0023] Where Δx i,i+1 =x ti+1 -x ti , Δy i,i+1 =y ti+1 -y ti , Δz i,i+1 =z ti+1 -z ti , Combined with the vertical plane equation, an observation point indirect adjustment error function formula is established: BX-L=0;

[0024] in,

[0025] The least squares solution is: X = (B T PB) -1 B T PL;

[0026] Among them, P is the weight of the observation value, and the weight is distributed equally;

[0027] For any point on a space circle, find the radius expression: r i =|p ti -O|;

[0028] Space circle fitting radius:

[0029] Evaluate the accuracy of the least squares spatial circle fitting and calculate the goodness of fit value after spatial circle fitting:

[0030] where r b Determined to be the standard pipe diameter.

[0031] The present invention also provides a pipe diameter measuring device, which includes an operating rod and a measuring part provided on the operating rod shaft, the measuring part including a power supply, and the measuring part having a spatial rectangular coordinate system model, wherein the X-axis surface of the spatial rectangular coordinate system model is surrounded by a plurality of first laser ranging modules that emit lasers outward with a zero point as the center of the circle, and the Y-axis surface of the spatial rectangular coordinate system model is surrounded by a plurality of second laser ranging modules that emit lasers outward with a zero point as the center of the circle, and the pitch circle diameter of the first laser ranging module is the same as the pitch circle diameter of the second laser ranging module; wherein one of the first laser ranging module or the second laser ranging module is located on the Z-axis line of the spatial rectangular coordinate system model.

[0032] Preferably, the measuring part includes a vertically arranged transverse bracket and a longitudinal bracket, a longitudinal bracket perpendicular to the transverse bracket is provided in the middle of one side surface of the transverse bracket, the transverse bracket is provided with a plurality of the first laser ranging modules, and the longitudinal bracket is provided with a plurality of the second laser ranging modules.

[0033] Preferably, a detachable connecting structure is provided near the lower end of the operating lever body, and the measuring portion is provided on one side of the connecting structure.

[0034] Preferably, the rod body of the operating rod located above the connecting structure is a telescopic rod.

[0035] Preferably, the measuring unit further includes an integrated circuit board connected to the power supply, and all the first laser ranging modules and all the second laser ranging modules are connected to the integrated circuit board.

[0036] Preferably, the measuring unit further comprises an early warning module connected to the power supply, and the early warning module is connected to the integrated circuit board;

[0037] The early warning module includes an ultrasonic rangefinder for detecting distance downward and a buzzer alarm.

[0038] The beneficial effects are:

[0039] 1. The measuring part does not need to be placed at the bottom of the pipe. It can measure in rainwater and sewage pipes with dirt at the bottom without being contaminated. The device has strong adaptability to underground environments.

[0040] 2. The measurement unit is composed of multiple laser ranging modules arranged horizontally and vertically. It can collect sufficient data during the operation, which is conducive to screening the quality of the data and checking the results, thereby improving the reliability of the measurement results;

[0041] 3. The laser ranging modules are arranged vertically on the horizontal and vertical brackets in an orderly manner. A custom rectangular coordinate system can be established to perform projection conversion on the coordinates of the ranging light points, effectively eliminating the longitudinal error caused by random placement of the device during operation, reducing the impact of lateral errors, improving the accuracy of the measurement results, and reducing the requirements on the operator's ability.

[0042] 4. Based on multiple second laser ranging modules, a detection straight line is fitted by measuring the coordinates of the light spots. The intercept from the light spot to the straight line can reflect the posture of the device in the pipeline, providing a basis for manual adjustment of the device posture, which can effectively improve work efficiency and reliability of results and reduce the difficulty of operating the device.

[0043] 5. The integrated circuit board can control all distance measurement modules to measure distance at the same time, ensuring the correctness of the relative relationship of the data, avoiding data differentiation errors caused by operators shaking the operating lever with their hands during field operations, and improving measurement accuracy and work efficiency.

[0044] 6. Due to the setting of the early warning module and LED lights, the report effectively prevents the measuring part from contacting the bottom of the manhole, causing equipment contamination and damage; the LED lights can improve the lighting conditions in the dark environment under the manhole, providing convenience for operators to observe the pipe material and judge the direction of water flow.

[0045] 7. The calculation method uses the RANSAC algorithm and the least squares space circle fitting principle to analyze and process the collected data, filter out abnormal data, and analyze the accuracy of the measurement results to improve the reliability of the results.

[0046] Additional technical features and advantages of the present invention will be more clearly explained in the following description, or can be understood through specific practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0048] Figure 1 It is a structural schematic diagram of the present invention;

[0049] Figure 2 It is a left side view of the present invention;

[0050] Figure 3 is a top view of the measuring portion of the present invention;

[0051] Figure 4 It is a bottom view of the measuring portion of the present invention;

[0052] Figure 5 It is a schematic diagram of the exploded structure of the connecting portion of the present invention;

[0053] Figure 6 It is a structural schematic diagram of the support column in the present invention;

[0054] Figure 7 The present invention is a flow chart for calculating pipe diameter.

[0055] The following are the descriptions of the reference numerals:

[0056] 1. Operating lever; 2. Measuring unit; 21. First laser ranging module; 22. Second laser ranging module; 23. Horizontal bracket; 24. Vertical bracket; 25. Integrated circuit board; 26. Ultrasonic rangefinder; 27. Buzzer alarm; 3. Connecting structure; 31. Connecting unit; 311. Fixed U-shaped piece; 312. Movable U-shaped piece; 313. Screw; 314. Connecting ear; 32. Horizontal plate; 33. T-shaped piece; 34. LED light; 4. Support column. DETAILED DESCRIPTION

[0057] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0058] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0059] In the description of the present invention, it should be understood that the terms indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only used to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, they cannot be understood as limiting the present invention.

[0060] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0061] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "inner," "outer," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0062] Furthermore, terms such as "horizontal," "vertical," and "overhanging" do not necessarily imply that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0063] In the present invention, unless otherwise expressly specified or limited, a first feature being above or below a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being above, above, and above the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being below, below, and below the second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0064] like Figure 1-2As shown, a device for measuring the diameter of an underground rainwater and sewage pipe comprises an operating rod 1 and a measuring portion 2 provided on the rod body of the operating rod 1;

[0065] As needed, the operating rod 1 can be a round rod or a square tube; preferably, the operating rod 1 is a square tube.

[0066] Further, such as Figure 1-2 As shown in Figures 5-6, to prevent the measuring portion 2 from contacting mud or rainwater at the bottom of the underground rainwater and sewage pipe, a detachable connecting structure 3 is provided near the lower end of the operating rod 1, and the measuring portion 2 is provided on one side of the connecting structure 3; or a connecting structure 3 is provided at the lower end of the operating rod 1, and a support column 4 is provided at the lower end of the connecting structure 3;

[0067] When measuring in this way, the measuring part 2 is at a certain distance from the bottom of the pipe, so it can measure in rainwater and sewage pipes with dirt remaining at the bottom without being contaminated, thereby increasing the adaptability to the underground environment.

[0068] In order to adapt to underground rainwater and sewage pipes of different diameters or buried depths, the rod body of the operating rod 1 located above the connecting structure 3 is a telescopic rod; further, the telescopic rod has a scale along its length. This setting can measure pipes of different depths by telescoping the operating rod 1, and the height of the bottom of the pipe from the ground can be indirectly obtained through the scale and related calculations, without being affected by the accumulation of dirt at the bottom of the pipe.

[0069] In some embodiments, as Figure 4-5 As shown, the connection structure 3 includes a connection portion 31 detachably connected to the lower end of the operating rod 1, a horizontal plate 32 is provided on one side of the connection portion 31, and a measuring portion 2 is provided on the upper surface of the horizontal plate 32;

[0070] As needed, such as Figure 4 As shown, a horizontally arranged T-shaped piece 33 is welded to one side of the connecting portion 31 , and a horizontal plate 32 is mounted on the wing end of the T-shaped piece 33 by screws.

[0071] As needed, the horizontal plate 32 can be regarded as the Z-axis plane in the above-mentioned spatial rectangular coordinate system;

[0072] As needed, such as Figure 5 As shown, the connecting portion 31 includes two U-shaped pieces with openings facing each other, wherein both side walls of one U-shaped piece are provided with screws that threadably engage with both side walls of the other U-shaped piece;

[0073] That is to say, if Figure 5As shown, the connecting portion 31 includes a fixed U-shaped part 311 and a movable U-shaped part 312. Screws 313 are welded on both sides of the fixed U-shaped part 311, and connecting ears 314 are provided on both sides of the movable U-shaped part 312 at positions corresponding to the screws 313. When connecting, the two connecting ears 314 of the movable U-shaped part 312 are respectively sleeved on the corresponding screws 313, and then a nut is screwed on the rod body of the screw 313 to complete the installation of the connecting portion 31.

[0074] With this arrangement, the measuring part 2 can be easily disassembled from the operating rod 1, making transportation easier and improving the convenience and safety of the device.

[0075] In some embodiments, as Figure 1-3 As shown, the measuring part 2 includes a power supply, and the measuring part 2 has a spatial rectangular coordinate system model. The X-axis surface of the spatial rectangular coordinate system model is surrounded by a plurality of first laser ranging modules 21 that emit lasers outward with the zero point as the center of the circle. The Y-axis surface of the spatial rectangular coordinate system model is surrounded by a plurality of second laser ranging modules 22 that emit lasers outward with the zero point as the center of the circle, and the pitch circle diameter of the first laser ranging module 21 is the same as the pitch circle diameter of the second laser ranging module 22; wherein, one of the first laser ranging module 21 or the second laser ranging module 22 is located on the Z-axis of the spatial rectangular coordinate system model;

[0076] The X-axis plane mentioned above can be understood as the plane where the X-axis and the Z-axis are located; the Y-axis plane is the plane where the Y-axis and the Z-axis are located.

[0077] Further, such as Figure 1-2 As shown, the spatial rectangular coordinate system model includes a vertically arranged horizontal bracket 23 and a vertical bracket 24. A vertical bracket 24 is provided perpendicular to the horizontal bracket 23 in the middle of one side thereof. The horizontal bracket 23 is provided with a plurality of first laser ranging modules 21, and the vertical bracket 24 is provided with a plurality of second laser ranging modules 22.

[0078] Specifically, the plane where the transverse bracket 23 is located can be understood as the X-axial plane, and the plane where the longitudinal bracket 24 is located can be understood as the Y-axial plane; as needed, the bottom surface of the transverse bracket 23 and the bottom surface of the longitudinal bracket 24 are both in contact with the upper surface of the horizontal plate 32, and the intersection line of the transverse bracket 23 and the longitudinal bracket 24 is the Z-axis line.

[0079] As needed, there are at least three first laser ranging modules 21 and at least two second laser ranging modules 22 .

[0080] In this embodiment, the radiation range of all the first laser ranging modules 21 is 180 degrees; preferably, the seven first laser ranging modules 21 are arranged at equal angles.

[0081] In this embodiment, two second laser ranging modules 22 are provided, and the lasers emitted by the two second laser ranging modules 22 are both tilted upward.

[0082] The measurement unit 2 is configured to consist of multiple laser ranging modules arranged horizontally and vertically. This allows for sufficient data to be collected during operation, facilitating data quality screening and result verification, thereby improving the reliability of the measurement results. Furthermore, a custom rectangular coordinate system can be established based on the layout of the laser ranging modules, and the coordinates of the ranging light spots can be projected and transformed, effectively eliminating longitudinal errors caused by random placement of devices during operation and reducing the impact of lateral errors, thereby improving the accuracy of measurement results and reducing the requirements for operator skills.

[0083] This arrangement allows for fitting a detection straight line to the coordinates of the ranging light spot using at least three laser ranging modules located on the Y-axis plane. The intercept from the light spot to the straight line can reflect the posture of the device in the pipeline, providing a basis for manually adjusting the posture of the device. This can effectively improve work efficiency and the reliability of the results, and reduce the difficulty of operating the device.

[0084] In some embodiments, as Figure 2-3 As shown, in order to realize automatic calculation results, the measuring part 2 further includes an integrated circuit board 25 connected to a power supply, and all first laser ranging modules 21 and all second laser ranging modules 22 are connected to the integrated circuit board 25;

[0085] Specifically, the integrated circuit board 25 is connected to the power supply via the micro USB power inlet, so that the device is connected to the current;

[0086] As needed, the integrated circuit board 25 can be mounted on the outer side of the horizontal bracket 23;

[0087] Furthermore, the integrated circuit board 25 includes a human-machine module, a control module, and a power supply module;

[0088] The human-machine module includes a Bluetooth device, a sound device, and an indicator light. The Bluetooth device model is HC-06. Specifically, the human-machine module receives commands sent by the user through the Bluetooth device, sends the commands to the control module, and provides sound and light prompts for the command transmission status. After the control module completes the command, it feeds back the processing results to the user through the Bluetooth device.

[0089] The control module includes a central processing unit, a distance measurement control unit and a distance measurement module access port. The control module receives information from the human-machine module, completes corresponding actions, and feeds back the processed results;

[0090] The power supply module includes a power inlet and an output port. The power supply module is connected to the human-machine module and the control module to provide power to the above modules.

[0091] Furthermore, a program is written into the terminal (mobile phone, tablet, integrated circuit board 25), and the terminal (mobile phone, tablet) can wirelessly connect to the integrated circuit board 25; when the terminal is an integrated circuit board 25, the device also has a display screen; preferably, the program is written into the mobile phone, that is, an APP with the program is downloaded into the mobile phone.

[0092] like Figure 7 As shown in the figure, after opening the program, the collected ranging data is displayed in the cross section, and the posture of the measuring part is adjusted by the straight line detection parameter d to collect qualified data. The collected data is filtered through projection transformation and RANSAC algorithm, and the final data is used for spatial circle fitting calculation, and the pipe diameter value and goodness of fit are output. At the same time, the telescopic rod scratches are read and the readings are input into the well depth calculation interface, which can output the well depth value.

[0093] This arrangement can control all distance measurement modules to measure distance at the same time through the integrated circuit board 25, ensuring the correctness of the relative relationship of the data, avoiding data differentiation errors caused by the operator holding the operating lever with his hand during the measurement process during field operations, and improving measurement accuracy and work efficiency.

[0094] In some embodiments, as Figure 2 and 4 As shown, in order to facilitate the staff to check the internal conditions of the underground rainwater and sewage pipes, such as the pipe material, the direction of water flow in the pipe, the approximate diameter of the pipe, etc., the lower surface of the horizontal plate 32 is provided with an LED light 34 connected to a power supply.

[0095] Such arrangement of the LED lamp 34 can improve the lighting conditions in the dark environment under the manhole, providing convenience for the observation and judgment of the operators.

[0096] In some embodiments, as Figure 1-4 As shown, the measuring part 2 further includes an early warning module connected to the power supply, and the early warning module is connected to the integrated circuit board 25;

[0097] The early warning module includes an ultrasonic rangefinder 26 for detecting the distance downward and a buzzer alarm 27;

[0098] Furthermore, the ultrasonic rangefinder 26 is installed on the lower surface of the horizontal plate 32, and the buzzer alarm 27 is installed on the upper surface of the horizontal plate 32;

[0099] Specifically, the ultrasonic rangefinder 26 sets a certain threshold value. When the distance between the ultrasonic rangefinder 26 and the bottom of the manhole is less than the threshold value, the buzzer alarm 27 starts to sound an alarm.

[0100] This arrangement can further prevent the measuring part 2 from contacting sewage or sludge at the bottom of the manhole, causing contamination of the equipment.

[0101] The operation method is as follows:

[0102] Use the connecting structure 3 to install the measuring part 2 on the operating rod 1, turn on the power, and then extend the measuring part 2 into the inner cavity of the underground rainwater and sewage pipe. During this process, constantly observe the status of the buzzer alarm 27, open the program, and start measuring. The ranging information of the laser ranging module is processed by the integrated circuit board 25 and transmitted to the hardware device interface. The hardware device interface displays information d and adjusts the posture of the measuring part. After meeting the requirements, check the output results to obtain the pipe diameter value and the measurement result accuracy evaluation value fit goodness, fit goodness R 2 The closer it is to 1, the higher the reliability of the measurement value.

[0103] like Figure 7 As shown, a method for measuring the diameter of an underground rainwater and sewage pipe includes the following steps: step 1: placing a measuring unit 2 in the inner cavity of the underground rainwater and sewage pipe to be measured, wherein the measuring unit 2 comprises a plurality of first laser ranging modules 21 arranged along an X-axis plane with a zero point as the center and emitting laser light outward, and a plurality of second laser ranging modules 22 arranged along a Y-axis plane with a zero point as the center and emitting laser light outward, and the pitch circle diameter of the first laser ranging module 21 is the same as the pitch circle diameter of the second laser ranging module 22;

[0104] Specifically, the X-axis plane can be understood as the XOZ plane in the spatial rectangular coordinate system, and the Y-axis plane can be understood as the YOZ plane in the spatial rectangular coordinate system, wherein the above-mentioned X-axis plane and Y-axis plane are two planes in the same spatial rectangular coordinate system;

[0105] In this embodiment, the number of the first laser ranging modules 21 is 6 or more, and the number of the second laser ranging modules 22 is 2 or 3; the specific number is not limited.

[0106] Step 2: Turn on the first laser ranging module 21 and the second laser ranging module 22, and adjust the posture of the measuring unit 2 so that the Y-axis plane is parallel to the axial plane of the underground rainwater and sewage pipe to be measured;

[0107] In this embodiment, the posture adjustment method of the measuring unit 2 is:

[0108] According to the geometric relationship of the laser ranging module, the light spot position p of the laser emitted by the laser ranging module located on the Z axis on the wall of the underground rainwater and sewage pipe to be measured is calculated. i Coordinate (x i ,y i , z i );

[0109] Any two second laser ranging modules 22 emit lasers at light points p on the inner wall of the underground rainwater and sewage pipe to be measured. i-1 、p i+1 , under ideal conditions p i-1 、pi 、p i+1 Collinear, p i-1 and p i+1 The equation of a line between two points is expressed as

[0110] Among them, p i The intercept distance from the point to the wall of the underground rainwater and sewage pipe to be measured is d, which is used to determine the posture of the measuring unit 2. d is expressed as: If d>m, the measuring part 2 needs to rotate and adjust its posture until d≤m;

[0111] The intercept error m is composed of measurement error and pipe manufacturing error, which can be solved by the error propagation law. Specifically, the measurement error is composed of distance measurement and installation angle errors, and the pipe error is obtained according to the relevant specifications of drainage pipes.

[0112] The vertical plane equation is derived from the straight line equation, and the vertical plane equation is the required construction projection surface; wherein the vertical plane equation is: ax+by+cz-1=0;

[0113] At the same time, all first laser distance measuring modules (21) and all second laser distance measuring modules (22) are enabled to perform distance measurement simultaneously;

[0114] Step 3: The vertical plane of the straight line formed by the light spots of the lasers emitted by the multiple second laser ranging modules 22 on the wall of the underground rainwater and sewage pipe to be measured is set as the projection plane; specifically, if the direction vector of the spatial straight line equation is Any vector in the plane passing through Pi-1 and perpendicular to the line So

[0115] According to the equation of the straight line, the perpendicular plane is deduced as: ax+by+cz-1=0; the perpendicular plane equation is the required construction projection surface;

[0116] Projecting all measuring points onto the projection surface can effectively eliminate the longitudinal tilt error caused by the arbitrary posture of the measuring part 2; solve the following equation Get the projected coordinates p of the measuring point ti (x ti ,y ti , z ti );

[0117] Step 4: Use space circle fitting to fit and obtain the two parameters of the center O (x0, y0, z0) and radius r of the fitting space circle;

[0118] Furthermore, in order to improve the accuracy of the measurement results, the RANSAC algorithm is used to filter out the erroneous points in the coordinates after the measurement points are projected in step 4:

[0119] Use the minimum model of space circle fitting to fit, get the two parameters of the center O (x0, y0, z0) and radius r of the random fitting space circle, and calculate the difference between the distance from all points to the center and the radius μ i , and compare it with the threshold T to screen out the qualified projection point coordinates.

[0120] When the number of qualified projection points q meets the set minimum number Q, calculate:

[0121] In this embodiment, Q takes a value of 4 or 5 as needed.

[0122] According to the straight line passing through the center of the circle and the midpoint of the chord in the space circle is perpendicular to the chord, the polynomial is obtained: Δx i,i+1 x0+Δy i,i+1 y0+Δz i,i+1 z0-l i =0;

[0123] Where Δx i,i+1 =x ti+1 -x ti , Δy i,i+1 =y ti+1 -y ti , Δz i,i+1 =z ti+1 -z ti ,

[0124] Specifically, μ i When <T, it is considered that the point meets the requirements, otherwise the above calculation is repeated;

[0125] In this embodiment, the value of T is 1 / 12 to 1 / 9 of the radius of the pipe to be measured, and the value of T is not greater than 50 mm. The diameter of the pipe to be measured can be roughly determined by visual observation by the operator.

[0126] Combined with the vertical plane equation, an observation point indirect adjustment error function is established: BX-L=0;

[0127] in,

[0128] The least squares solution is: X = (B T PB) -1 B T PL;

[0129] Among them, P is the weight of the observation value, and the weight is distributed equally;

[0130] For any point on a space circle, find the radius expression: r i =|p ti -O|;

[0131] Space circle fitting radius:

[0132] Evaluate the accuracy of the least squares spatial circle fitting and calculate the goodness of fit value after spatial circle fitting:

[0133] where r b Determined to be the standard pipe diameter.

[0134] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for measuring the diameter of underground rainwater and sewage pipes, characterized by: The following steps are involved: Step 1: placing a measuring part (2) in the inner cavity of an underground rainwater and sewage pipe to be measured, wherein the measuring part (2) has a spatial rectangular coordinate system model, the X-axis surface of the spatial rectangular coordinate system model is surrounded by at least three first laser ranging modules (21) that emit laser light outwards with a zero point as the center, and the Y-axis surface of the spatial rectangular coordinate system model is surrounded by at least two second laser ranging modules (22) that emit laser light outwards with a zero point as the center, and the pitch circle diameter of the first laser ranging module (21) is the same as the pitch circle diameter of the second laser ranging module (22); wherein one of the first laser ranging module (21) or the second laser ranging module (22) is located on the Z-axis of the spatial rectangular coordinate system model; Step 2: Turn on the first laser distance measuring module (21) and the second laser distance measuring module (22), and adjust the posture of the measuring unit (2) so that the Y-axis plane is parallel to the axial plane of the underground rainwater and sewage pipe to be measured, and at the same time, all the first laser distance measuring modules (21) and all the second laser distance measuring modules (22) perform distance measurement simultaneously; The method for adjusting the posture of the measuring part (2) is: According to the geometric relationship of the laser ranging module, the light spot position p of the laser emitted by the laser ranging module located on the Z axis on the wall of the underground rainwater and sewage pipe to be measured is calculated. i Coordinate (x i ,y i , z i ); Any two second laser distance measuring modules (22) emit lasers at light points p on the inner wall of the underground rainwater and sewage pipe to be measured. i-1 、p i+1 , under ideal conditions p i-1 、p i 、p i+1 Collinear, p i-1 and p i+1 The equation of a line between two points is expressed as Among them, p i Point to p i-1 and p i+1 The intercept of the two-point straight line is d, and the posture of the measuring unit (2) is determined by d. d is expressed as: If d>m, the measuring part (2) needs to rotate and adjust its posture until d≤m; Among them, the intercept error m is composed of measurement error and pipeline manufacturing error, which can be solved by the error propagation law; The vertical plane equation is derived from the straight line equation, and the vertical plane equation is the required construction projection surface; wherein the vertical plane equation is: ax+by+cz-1=0; Step 3: The vertical plane formed by the light spots of the lasers emitted by the multiple second laser ranging modules (22) on the wall of the underground rainwater and sewage pipe to be measured is set as the projection plane, and all the measuring points are projected onto the projection plane, which can effectively eliminate the longitudinal tilt error caused by the arbitrary posture placement of the measuring part (2); solve the following equation Get the projected coordinates p of the measuring point ti (x ti ,y ti , z ti ); Step 4: Use space circle fitting to fit and obtain the two parameters of the center O (x0, y0, z0) and radius r of the fitting space circle.

2. The method for measuring the diameter of an underground rainwater and sewage pipe according to claim 1, characterized in that: Use the RANSAC algorithm to filter out the erroneous points in the projected coordinates of the measurement points described in step 3; The minimum model of spatial circle fitting is used to fit the center O(x0, y0, z0) and radius r of the randomly fitted spatial circle. The difference μi between the distance from all points to the center and the radius is calculated and compared with the threshold T to screen out the qualified projection point coordinates. When the number of qualified projection points q meets the set minimum number Q, calculate: According to the straight line passing through the center of the circle and the midpoint of the chord in the space circle is perpendicular to the chord, the polynomial is obtained: Δx i,i+1 x0+Δy i,i+1 y0+Δz i,i+1 z0-l i =0; Where Δx i,i+1 =x ti+1 -x ti , Δy i,i+1 =y ti+1 -y ti , Δz i,i+1 =z ti+1 -z ti , Combined with the vertical plane equation, an observation point indirect adjustment error function formula is established: BX-L=0; in, The least squares solution is: X = (B T PB) -1 B T PL; Among them, P is the weight of the observation value, and the weight is distributed equally; For any point on a space circle, find the radius expression: r i =|p ti -O|; Space circle fitting radius: Evaluate the accuracy of the least squares spatial circle fitting and calculate the goodness of fit value after spatial circle fitting: where r b Determined to be the standard pipe diameter.

3. A method for measuring the diameter of an underground rainwater and sewage pipe according to claim 1 or 2, characterized in that: The pipe diameter measuring method requires the use of the following device, which comprises an operating rod (1) and a measuring part (2) provided on the rod body of the operating rod (1), wherein the measuring part (2) comprises a power supply, and the measuring part (2) has a spatial rectangular coordinate system model, wherein a plurality of first laser distance measuring modules (21) for emitting laser light outwards are arranged on the X-axis plane of the spatial rectangular coordinate system model with a zero point as the center of the circle, and a plurality of second laser distance measuring modules (22) for emitting laser light outwards are arranged on the Y-axis plane of the spatial rectangular coordinate system model with the zero point as the center of the circle, and the pitch circle diameter of the first laser distance measuring module (21) is the same as the pitch circle diameter of the second laser distance measuring module (22); wherein one of the first laser distance measuring module (21) or the second laser distance measuring module (22) is located on the Z-axis line of the spatial rectangular coordinate system model.

4. The method for measuring the diameter of an underground rainwater and sewage pipe according to claim 3, characterized in that: The measuring part (2) comprises a vertically arranged transverse bracket (23) and a longitudinal bracket (24); a longitudinal bracket (24) perpendicular to the transverse bracket (23) is provided in the middle of one side surface; the transverse bracket (23) is provided with a plurality of the first laser ranging modules (21); and the longitudinal bracket (24) is provided with a plurality of the second laser ranging modules (22).

5. The method for measuring the diameter of underground rainwater and sewage pipes according to claim 3, characterized in that: A detachable connecting structure (3) is provided near the lower end of the operating rod (1), and the measuring portion (2) is provided on one side of the connecting structure (3).

6. The method for measuring the diameter of underground rainwater and sewage pipes according to claim 5, characterized in that: The rod body of the operating rod (1) located above the connecting structure (3) is a telescopic rod.

7. The method for measuring the diameter of underground rainwater and sewage pipes according to claim 3, characterized in that: The measuring unit (2) further comprises an integrated circuit board (25) connected to the power supply, and all first laser distance measuring modules (21) and all second laser distance measuring modules (22) are connected to the integrated circuit board (25).

8. The method for measuring the diameter of underground rainwater and sewage pipes according to claim 3, characterized in that: The measuring unit (2) further includes an early warning module connected to the power supply, and the early warning module is connected to an integrated circuit board (25); The early warning module includes an ultrasonic rangefinder (26) for detecting distance downward and a buzzer alarm (27).

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