Cable force identification method, device and equipment based on three-dimensional point cloud density

Abstract

The present application relates to the technical field of cable-stayed cable analysis, in particular to a cable-stayed cable force identification method, device and equipment based on three-dimensional point cloud density. The present application reduces the three-dimensional coordinates of each point on the cable-stayed cable to two-dimensional point coordinates, then fits the micro-section two-dimensional coordinates of each point cloud micro-section according to the two-dimensional point coordinates, then establishes a target function about the horizontal component force based on the micro-section two-dimensional coordinates, obtains the target value of the horizontal component force by solving the target function, and finally calculates the cable force value of the cable-stayed cable by the target value. Through the above analysis, the present application fits the micro-section two-dimensional coordinates of each point cloud micro-section, which can reduce the error of the micro-section two-dimensional coordinates, and further improve the accuracy of the finally calculated cable force value.

Description

Technical Field

[0001] The present invention relates to the technical field of stay cable analysis, and in particular to a method, device and equipment for identifying stay cable forces based on three-dimensional point cloud density. Background Art

[0002] 3D laser scanning technology has a longer measurement range, significantly reducing the risks of working at height. It also offers centimeter- or even millimeter-level data accuracy, enabling it to fully capture the three-dimensional shape of a structure. Therefore, 3D laser scanning technology is being applied to measuring the cable force (cable force is the tension experienced by a stay cable, which is a tilted, fixed cable). Existing technology uses 3D laser scanning to obtain the 3D coordinates of each point on the stay cable, fits the cable centerline to each of these 3D coordinates, and uses this to calculate the cable force. However, fitting the centerline to each of these 3D coordinates reduces the accuracy of the centerline, which in turn reduces the accuracy of the calculated cable force.

[0003] In summary, the existing technology reduces the accuracy of the solved cable force.

[0004] Therefore, the existing technology needs to be improved and enhanced. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a method, device and equipment for identifying cable forces based on three-dimensional point cloud density, which solves the problem that the existing technology reduces the accuracy of the solved cable forces.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for identifying cable forces based on three-dimensional point cloud density, comprising:

[0008] The three-dimensional coordinates of each point of the cable are collected by a three-dimensional laser, and the three-dimensional coordinates are reduced in dimension to obtain the two-dimensional coordinates of the point;

[0009] Dividing the two-dimensional coordinates of each point into a plurality of point cloud micro-segments, and determining the micro-segment two-dimensional coordinates of each point cloud micro-segment;

[0010] Based on the two-dimensional coordinates of the micro-segment, an objective function is established with a horizontal force component as a parameter to be solved, and a target value of the horizontal force component is obtained by solving the objective function, where the horizontal force component is the component of the cable force of the inclined cable in the horizontal direction;

[0011] The cable force value of the stay cable is determined according to the target value.

[0012] In one implementation, the dimensionality reduction processing of the three-dimensional coordinates to obtain the two-dimensional coordinates of the point includes:

[0013] Obtaining an upper fixing point and a lower fixing point of the stay cable, wherein the upper fixing point and the lower fixing point are both points for fixing the stay cable, and the upper fixing point is located obliquely above the lower fixing point;

[0014] Determine the projection point of the upper fixed point on the horizontal plane, and determine a two-dimensional rope-shaped plane formed by the projection point, the lower fixed point, and the upper fixed point, wherein the horizontal plane is the horizontal plane where the lower fixed point is located;

[0015] Determining a normal vector of the two-dimensional rope-shaped plane and determining a horizontal axis direction vector of a two-dimensional coordinate system with the upper fixed point as a starting point and the lower fixed point as an end point;

[0016] The three-dimensional coordinates are processed by dimensionality reduction according to the horizontal axis direction vector and the normal vector to obtain the two-dimensional coordinates of the point.

[0017] In one implementation, the dimensionality reduction processing of the three-dimensional coordinates based on the horizontal axis direction vector and the normal vector to obtain the two-dimensional coordinates of the point includes:

[0018] Performing a cross product operation on the horizontal axis direction vector and the normal vector to obtain a vertical axis direction vector of the vertical axis of the two-dimensional coordinate system;

[0019] The three-dimensional coordinates are subjected to dimensionality reduction processing according to the horizontal axis direction vector and the vertical axis direction vector of the vertical coordinate axis to obtain the two-dimensional coordinates of the point.

[0020] In one implementation, determining the two-dimensional coordinates of each of the point cloud micro-segments includes:

[0021] Determine a mean of the ordinates corresponding to the two-dimensional ordinates of the points in each of the point cloud micro-segments, where the two-dimensional ordinates of the points are the ordinates included in the two-dimensional ordinates of each point in each of the point cloud micro-segments;

[0022] For each of the point cloud micro-segments, counting the number of the two-dimensional vertical coordinates of the points that are greater than the mean vertical coordinate, and obtaining the total number of the two-dimensional vertical coordinates of the points contained in each of the point cloud micro-segments;

[0023] Determining a compensation factor for each of the point cloud micro-segments based on the number and the total number;

[0024] Correcting the vertical coordinate mean of each point cloud micro-segment according to the compensation factor of each point cloud micro-segment to obtain a vertical coordinate correction value;

[0025] The mean abscissa corresponding to the two-dimensional abscissa in each point cloud micro-segment is determined, and the ordinate correction value of each point cloud micro-segment and the mean abscissa of each point cloud micro-segment are used as the micro-segment two-dimensional coordinate of each point cloud micro-segment.

[0026] In one implementation, establishing an objective function with the horizontal force component as a parameter to be solved based on the two-dimensional coordinates of the micro-segment includes:

[0027] Based on the mean value of the horizontal coordinate of each point cloud micro-segment, a cable mechanics model is established with the horizontal component as the parameter to be solved, wherein the cable mechanics model includes a catenary cable mechanics model and a parabolic cable mechanics model;

[0028] Establishing a target sub-function for each point cloud micro-segment according to the cable mechanical model corresponding to each point cloud micro-segment and the vertical coordinate correction value of each point cloud micro-segment;

[0029] According to the objective sub-function of each point cloud micro-segment, the objective function of the inclined cable with respect to the horizontal component force is obtained.

[0030] In one implementation, obtaining the target value of the horizontal force component by solving the objective function includes:

[0031] A quasi-Newton iterative algorithm is applied to the objective function to determine the minimum value of the objective function, and the horizontal component force corresponding to the minimum value is used as the target value.

[0032] In one implementation, determining the cable force value of the stay cable according to the target value includes:

[0033] The target value is substituted into the cable mechanics model to obtain the cable force value of the inclined cable.

[0034] In a second aspect, an embodiment of the present invention further provides a device for identifying cable force based on three-dimensional point cloud density, wherein the device includes the following components:

[0035] A dimensionality reduction module is used to collect the three-dimensional coordinates of each point of the inclined cable through a three-dimensional laser, and perform dimensionality reduction processing on the three-dimensional coordinates to obtain the two-dimensional coordinates of the point;

[0036] A correction module, configured to divide the two-dimensional coordinates of each point into a plurality of point cloud micro-segments, and determine the two-dimensional coordinates of each point cloud micro-segment;

[0037] a target value calculation module, configured to establish, based on the two-dimensional coordinates of the micro-segment, an objective function with a horizontal force component as a parameter to be solved, and obtain a target value of the horizontal force component by solving the objective function, wherein the horizontal force component is the component of the cable force of the inclined cable in the horizontal direction;

[0038] The cable force calculation module is used to determine the cable force value of the inclined cable according to the target value.

[0039] In a third aspect, an embodiment of the present invention further provides a terminal device, wherein the terminal device includes a memory, a processor, and a cable-stayed cable force identification program based on three-dimensional point cloud density stored in the memory and runnable on the processor. When the processor executes the cable-stayed cable force identification program based on three-dimensional point cloud density, the steps of the above-mentioned cable-stayed cable force identification method based on three-dimensional point cloud density are implemented.

[0040] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, on which is stored a cable-stayed cable force identification program based on three-dimensional point cloud density. When the cable-stayed cable force identification program based on three-dimensional point cloud density is executed by a processor, the steps of the above-mentioned cable-stayed cable force identification method based on three-dimensional point cloud density are implemented.

[0041] Beneficial Effects: The present invention reduces the 3D coordinates of each point on the cable to 2D coordinates. It then fits the 2D coordinates of each point cloud micro-segment to the 2D coordinates. It then establishes an objective function for the horizontal force component based on the 2D coordinates of the micro-segment. The objective function is solved to obtain a target value for the horizontal force component, and the cable force is calculated using this target value. The above analysis shows that fitting the 2D coordinates of each point cloud micro-segment in the present invention can reduce the error in the 2D coordinates of the micro-segment, thereby improving the accuracy of the ultimately calculated cable force. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is the overall flow chart of the present invention;

[0043] Figure 2 Schematic diagram of the shape of the inclined cable in space in an embodiment of the present invention;

[0044] Figure 3 Dimensionality reduction flowchart in an embodiment of the present invention;

[0045] Figure 4 Schematic diagram of a catenary cable mechanical model in an embodiment of the present invention;

[0046] Figure 5 : is a force analysis diagram of the stay cable in an embodiment of the present invention;

[0047] Figure 6 : is a force analysis diagram of a parabolic cable in an embodiment of the present invention;

[0048] Figure 7 This is a flow chart for identifying cable force in an embodiment of the present invention;

[0049] Figure 8 This is a structural diagram of the device for identifying the force of a stay cable based on three-dimensional point cloud density provided by the present invention;

[0050] Figure 9 This is a block diagram of the internal structure of a terminal device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0051] The following is a clear and complete description of the technical solutions of the present invention in conjunction with the embodiments and the accompanying drawings. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0052] Research has found that 3D laser scanning technology has a longer measurement range, significantly reducing the risks of working at height. It also offers centimeter- or even millimeter-level data accuracy, enabling it to fully capture the three-dimensional shape of a structure. Therefore, 3D laser scanning technology has been applied to measuring the cable force (cable force is the tension exerted on a cable, which is a tilted, fixed cable) of a stay cable. Existing technology uses 3D laser scanning to obtain the 3D coordinates of each point on the cable, fits the cable centerline to each 3D coordinate, and uses this to calculate the cable force. However, fitting the centerline to each 3D coordinate reduces the accuracy of the centerline, which in turn reduces the accuracy of the calculated cable force.

[0053] In order to solve the above technical problems, the present invention provides a method, device and equipment for identifying cable forces based on three-dimensional point cloud density, which solves the problem that the existing technology reduces the accuracy of the solved cable forces.

[0054] The cable force identification method based on 3D point cloud density of this embodiment can be applied to a terminal device, which can be a terminal product with laser data processing function, such as a computer. Figure 1 As shown in , the cable force identification method based on three-dimensional point cloud density specifically includes the following steps:

[0055] S100, collecting the three-dimensional coordinates of each point of the inclined cable by three-dimensional laser, and performing dimensionality reduction processing on the three-dimensional coordinates to obtain the two-dimensional coordinates of the point.

[0056] S200, dividing the two-dimensional coordinates of each point into a plurality of point cloud micro-segments, and determining the two-dimensional coordinates of each point cloud micro-segment;

[0057] S300, based on the two-dimensional coordinates of the micro-segment, establishing an objective function with a horizontal force component as a parameter to be solved, and obtaining a target value of the horizontal force component by solving the objective function, where the horizontal force component is the component of the cable force of the inclined cable in the horizontal direction;

[0058] S400: Determine the cable force value of the stay cable according to the target value.

[0059] Example 1: In this example, Figure 2 As shown, the laser transmitter is fixed at point B on the horizontal plane, and the arc The cable is a stay cable, point A is the lower endpoint of the stay cable, point O is the upper endpoint of the stay cable, and the projection of point O on the horizontal plane is B. Point A and point O are both fixed points of the stay cable. Point O is the origin of the three-dimensional coordinate system, the direction from point O to point A is the x-axis of the three-dimensional coordinate system, the direction perpendicular to the x-axis at point O is the y-axis of the three-dimensional coordinate system, and the direction perpendicular to the plane where the x-axis and y-axis are located and upward at point O is the positive direction of the z-axis of the three-dimensional coordinate system. In this three-dimensional coordinate system, the three-dimensional coordinates of each point on the stay cable are collected by laser light emitted by a laser transmitter. In this embodiment, step S100 includes the following specific steps S101 to S105:

[0060] S101, obtaining the upper fixing point O and the lower fixing point A of the inclined cable, wherein the upper fixing point and the lower fixing point are both points for fixing the inclined cable, such as Figure 2 As shown, the upper fixing point O is located obliquely above the lower fixing point A.

[0061] S102, determining a projection point B of the upper fixed point O on a horizontal plane, and determining a two-dimensional rope-shaped plane OAB formed by the projection point B, the lower fixed point A, and the upper fixed point O, wherein the horizontal plane is the horizontal plane where the lower fixed point is located.

[0062] S103, such as Figure 3 As shown, determine the normal vector of the two-dimensional rope plane OAB And determine the horizontal axis direction vector with the upper fixed point O as the starting point and the lower fixed point A as the end point

[0063] The coordinates of point O, point A, and point B in the three-dimensional coordinate system are (x o ,y o ,z o )、(x a ,y a ,z a )、(x o ,y o ,z a ), since point B is the projection of point O, point B and point O have the same x o 、y o , and since point B and point A are on the same horizontal plane, point B and point A have the same z a .

[0064]

[0065] S104, the horizontal axis direction vector and the normal vector Perform a cross product operation to obtain the vertical axis y of the two-dimensional coordinate system, the vertical axis direction vector

[0066]

[0067] S105, according to the horizontal axis direction vector and the longitudinal direction vector of the longitudinal axis The three-dimensional coordinates are subjected to dimensionality reduction processing to obtain the two-dimensional coordinates of the point.

[0068] That is, the horizontal axis direction vector The x-axis of the two-dimensional coordinate system and the vertical axis direction vector The y-axis of the two-dimensional coordinate system. The three-dimensional coordinates (x k ,y k ,z k ) to perform dimensionality reduction processing and obtain the two-dimensional coordinates of point k (x' k ,y' k ):

[0069]

[0070]

[0071] The two-dimensional coordinates of all points on the cable constitute the two-dimensional point cloud coordinate set D.

[0072] Example 2, based on Example 1, in this example, step S200 includes the following specific steps S201 to S205:

[0073] S201, determining the mean value of the vertical coordinates corresponding to the two-dimensional vertical coordinates of each point in the point cloud micro-segment The two-dimensional vertical coordinate of the point is the vertical coordinate contained in the two-dimensional coordinate of each point in each point cloud micro-segment.

[0074] Step S100 obtains a two-dimensional point cloud coordinate set D, and divides the point cloud data into N point cloud micro-segments according to the horizontal coordinate range of the point cloud. The point cloud set S of the mth point cloud micro-segment is m :

[0075] S m ={(x,y)∈D|x m ≤x≤x m+1}

[0076] x m and xm+1 are the minimum and maximum values ​​of the horizontal coordinate of the mth point cloud micro-segment respectively.

[0077] is the mean of the two-dimensional ordinates of all points contained in the m-th point cloud micro-segment, Satisfies the following relationship:

[0078]

[0079] S m is the total number of points contained in the mth point cloud micro-segment, y i is the ordinate of the i-th point in the m-th point cloud micro-segment (that is, the two-dimensional ordinate of the i-th point).

[0080] For example, there are 20 points on the cable, and these 20 points have 20 two-dimensional coordinates (two-dimensional coordinates include horizontal and vertical coordinates). The 20 points are divided into 5 point cloud micro-segments according to the horizontal coordinates. The first point cloud micro-segment includes the horizontal coordinate of the first point to the horizontal coordinate of the fifth point and the vertical coordinate of the first point to the vertical coordinate of the fifth point; the second point cloud micro-segment includes the horizontal coordinate of the sixth point to the horizontal coordinate of the tenth point and the vertical coordinate of the sixth point to the vertical coordinate of the tenth point; the third point cloud micro-segment includes the horizontal coordinate of the eleventh point to the horizontal coordinate of the fifteenth point and the vertical coordinate of the eleventh point to the vertical coordinate of the fifteenth point; the fourth point cloud micro-segment includes the horizontal coordinate of the sixteenth point to the horizontal coordinate of the twentieth point and the vertical coordinate of the sixteenth point to the vertical coordinate of the twentieth point. For the first point cloud micro-segment, the sum of the vertical coordinate of the first point plus the vertical coordinate of the second point plus the vertical coordinate of the third point plus the vertical coordinate of the fourth point plus the vertical coordinate of the fifth point divided by five is the average of the two-dimensional vertical coordinates of the points in the first point cloud micro-segment.

[0081] S202: For each point cloud micro-segment, count the number of the two-dimensional vertical coordinates of the points that are greater than the mean vertical coordinate, and obtain the total number S of the two-dimensional vertical coordinates of the points contained in each point cloud micro-segment. m .

[0082] S203: Determine a compensation factor for each of the point cloud micro-segments according to the number and the total number.

[0083] Let's illustrate S202 and S203, taking the mth point cloud micro-segment as an example.

[0084] Compensation factor C of the mth point cloud micro-segment m :

[0085]

[0086] Where, Meaning: when yi Greater than or equal to When , it is accumulated by 1, that is, It is the number of points in the mth point cloud micro-segment whose two-dimensional vertical coordinates are greater than the mean (that is, the number of points in the mth point cloud micro-segment whose two-dimensional vertical coordinates are greater than the mean).

[0087] After projecting the 3D point cloud data onto the 2D cable-shaped plane, the centerline of the projected points on the 2D plane needs to be extracted to represent the cable shape. However, when acquiring point cloud data using 3D laser scanning technology, the point cloud density at different cross-sectional locations of the same cable often varies due to factors such as ambient lighting, surface reflectivity, occlusion, scanning angle, and scanning distance. This means that the 2D coordinates after dimensionality reduction contain errors. This embodiment eliminates this error through a compensation factor, thereby improving the accuracy of the 2D coordinates used for cable force calculation.

[0088] S204 : Correcting the vertical coordinate mean of each point cloud micro-segment according to the compensation factor of each point cloud micro-segment to obtain a vertical coordinate correction value.

[0089] For the mth point cloud micro segment, the mean vertical coordinate The vertical mean of the corrected sum is That is, the vertical coordinate correction value is

[0090]

[0091] is the indicator function, when The value is 1 when , otherwise it is 0.

[0092] S205, determining the mean value of the horizontal coordinate corresponding to the two-dimensional horizontal coordinate in each point cloud micro-segment The vertical coordinate correction value of each point cloud micro-segment and the horizontal coordinate average of each point cloud micro-segment are used as the micro-segment two-dimensional coordinate of each point cloud micro-segment.

[0093] is the mean value of all two-dimensional horizontal coordinates in the m-th point cloud micro-segment, It is the two-dimensional coordinate of the mth point cloud micro-segment.

[0094] Embodiment 3, based on embodiment 1 or embodiment 2, in this embodiment, step S300 includes the following specific steps S301, S302, S303, and S304:

[0095] S301, based on the mean value of the horizontal coordinate of each point cloud micro-segment, establish a cable mechanics model with the horizontal component as the parameter to be solved The cable mechanics model includes a catenary cable mechanics model and a parabola cable mechanics model.

[0096] H in is the horizontal component, and H is an unknown parameter. Cable mechanics model Including catenary cable mechanics model or parabolic cable mechanics model.

[0097] When the cable mechanics model is a catenary cable mechanics model, l m is the length of the mth point cloud micro-segment in the horizontal direction, like Figure 4 As shown, h m is the height of the mth point cloud micro-segment in the vertical direction, and q is the cable weight of the mth point cloud micro-segment.

[0098] Among them, the θ involved in the catenary cable mechanical model is x It is based on the following principles:

[0099] In the catenary cable mechanical model, the vertical distributed load concentration of the cable can be expressed as:

[0100]

[0101] Substitute the above formula into The differential equation of the catenary cable mechanical model can be obtained:

[0102]

[0103] Introduce boundary conditions and set the points (0, 0) and (l i , h i ) into the above formula, we can get the relationship between the shape and cable force of the catenary cable:

[0104]

[0105] By differentiating the expression of y, we can get θ x expression.

[0106] When the cable mechanics model is a parabolic cable mechanics model,

[0107]

[0108] Where, represents the angle between the chord between the two endpoints of the m-th point cloud micro-segment and the horizontal axis, in is the inclination angle θ at any position x on the cable x .

[0109] When the cable mechanics model is a parabolic cable mechanics model, the θ involved in the modelx It is derived as follows:

[0110] The force analysis of the cable Figure 5 As shown, Figure 5 Figure a shows the stress condition of the cable segment. Figure 5 Figure b shows the force diagram of the cable differential unit. Based on the force analysis diagram of the inclined cable, the mechanical equilibrium equation of the cable differential segment can be obtained:

[0111]

[0112] Where H is the horizontal component of the cable force (an unknown parameter that needs to be solved), q y is the vertical distributed load concentration of the cable, q x is the lateral distributed load concentration of the cable. In the cable force calculation process of the inclined cable, in general, the horizontal distributed load concentration of the cable q x = 0, then the horizontal component force H of the cable is a constant. By subdividing the cable into sections, we can get the following mechanical equilibrium equation:

[0113]

[0114] Figure 6 This is the parabolic cable force analysis diagram, combined with The mechanical equilibrium equation of the parabolic cable can be established:

[0115]

[0116] Integrate the above equation twice and set the boundary conditions (0, 0) and (l i , h i ) into the equation, we can get the parabola equation:

[0117]

[0118] Depend on The horizontal tension of the cable can be obtained as:

[0119]

[0120] The corresponding sag curve formula is as follows:

[0121]

[0122] make We get x = l i / 2, indicating that the maximum sag of the parabola must be at the mid-span point, and thus we can get:

[0123]

[0124] right Derivation, that is, θ x .

[0125] S302, according to the cable mechanics model corresponding to each point cloud micro section and the longitudinal coordinate correction value of each point cloud micro section, the target sub function of each point cloud micro section is established:

[0126]

[0127] S303, according to the target sub function of each point cloud micro section The target function E(H) of the cable with respect to the horizontal component force is obtained.

[0128]

[0129] In this embodiment, the expression of E(H) is obtained based on the following derivation: after obtaining the two-dimensional linear point set {x i ,y i} of the cable based on the point cloud plane projection algorithm and the mean value fitting improved algorithm considering the point cloud density, the two-dimensional linear point set {x i ,y i} needs to be fitted into a catenary or a parabola. The horizontal component force H of the cable can be solved from the two-dimensional linear point set {x i ,y i}, and the following regression equation can be established:

[0130] y=f(x,H)+ε

[0131] In the formula, ε is the error of the regression model, that is, the difference between the two-dimensional linear point set {x i ,y i} and the theoretical linear model (catenary model, parabola model). The initial value H0 of the horizontal component force of the cable is input, Taylor expansion of formula (5-25) is carried out at H0, and the first two orders of expansion are taken, and the following formula can be obtained:

[0132]

[0133] Then, the selected

[0134] The residual sum of squares generated by the equation is the target function E(H).

[0135] S304, applying the quasi-Newton iteration algorithm to the target function, determining the minimum value of the target function, and taking the horizontal component force corresponding to the minimum value as the target value F H .

[0136] , and As m and N are both known, H is an unknown quantity, that is, H is a parameter that needs to be solved. Each point cloud micro-segment has an H that needs to be solved, that is, to determine N Hs so that Get the minimum value, that is, when When the minimum value is obtained, the value of N H at this time is the target value F of the horizontal component force H .

[0137] use Figure 7 The cable force calculation method based on cable shape in The minimum value includes the following specific steps:

[0138] The first step is initialization settings: select the initial parameter H0 and initialize the approximation B0 of the Hessian matrix, usually the identity matrix.

[0139] The second step is iteration: in each iteration, the gradient is calculated, the search direction is calculated, the line search is performed, the parameters are updated, the difference vector is calculated, and the Hessian matrix approximation is updated.

[0140] Among them, the gradient is calculated:

[0141]

[0142] Where, is the gradient of function f with respect to H.

[0143] Use the inverse of the current approximated Hessian matrix B k Calculate the search direction:

[0144]

[0145] Line Search: Determine Step Size α k , so that the following objective function E(H) is reduced:

[0146] α k =argminE(H k +αp k )

[0147] Use the found step size α k Update parameters:

[0148] H k+1 =H k +α k p k

[0149] Calculate the difference vector s k and y k :

[0150] s k =H k+1-H k

[0151]

[0152] Update the Hessian matrix approximation:

[0153] Use the difference vector s k and y k Update the Hessian matrix approximation B k :

[0154]

[0155] The third step is to determine the termination condition: check whether the norm of the gradient is less than the preset threshold If not satisfied, jump back to step 1; if satisfied, terminate the iteration.

[0156] Step 4: Return the result: return the final parameter H k+1 .

[0157] Example 4, based on Example 1 or Example 2 or Example 3, in this example, step S400 includes the following specific steps: substituting the target value into the cable mechanics model to obtain the cable force value T of the inclined cable m .

[0158] Cable force value T m is the cable force value of the mth point cloud micro-segment. When the cable mechanical model is the catenary cable mechanical model,

[0159]

[0160] F in the formula H It is the target value of the horizontal component of the mth point cloud micro-segment.

[0161] When the cable mechanical model is a parabolic model,

[0162]

[0163] F in the formula H It is also the target value of the horizontal component of the m-th point cloud micro-segment.

[0164] In summary, the present invention achieves a non-invasive cable tension measurement with high recognition accuracy and practicality. High-precision geometric data obtained by laser scanning, such as the cable's spatial sag, inclination, and cable length, can provide reliable parameters for existing practical cable tension calculation formulas. This invention avoids the challenges of sensor-based cable tension measurement, such as limited service life, high maintenance costs, and frequency data reliability, providing a more reliable and economical approach to cable tension identification.

[0165] This embodiment also provides a device for identifying the force of a stay cable based on three-dimensional point cloud density. Figure 8 As shown, the device includes the following components:

[0166] Dimensionality reduction module 01 is used to collect the three-dimensional coordinates of each point of the inclined cable through three-dimensional laser, and perform dimension reduction processing on the three-dimensional coordinates to obtain the two-dimensional coordinates of the point;

[0167] Correction module 02, used to divide the two-dimensional coordinates of each point into a plurality of point cloud micro-segments, and determine the two-dimensional coordinates of each point cloud micro-segment;

[0168] A target value calculation module 03 is configured to establish an objective function with a horizontal force component as a parameter to be solved based on the two-dimensional coordinates of the micro-segment, and obtain a target value of the horizontal force component by solving the objective function, where the horizontal force component is the component of the cable force of the inclined cable in the horizontal direction;

[0169] The cable force calculation module 04 is used to determine the cable force value of the inclined cable according to the target value.

[0170] Based on the above embodiment, the present invention further provides a terminal device, whose principle block diagram can be shown as follows: Figure 9 As shown. The terminal device includes a processor, a memory, a network interface, and a display screen connected via a system bus. The processor of the terminal device is used to provide computing and control capabilities. The memory of the terminal device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the terminal device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, a method for identifying cable force based on three-dimensional point cloud density is implemented. The display screen of the terminal device can be a liquid crystal display or an electronic ink display.

[0171] Those skilled in the art will understand that Figure 9 The principle block diagram shown in the figure is only a block diagram of a partial structure related to the solution of the present invention, and does not constitute a limitation on the terminal device to which the solution of the present invention is applied. The specific terminal device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0172] In one embodiment, a terminal device is provided. The terminal device includes a memory, a processor, and a three-dimensional point cloud density-based stay cable force identification program stored in the memory and executable on the processor. When the processor executes the three-dimensional point cloud density-based stay cable force identification program, the following operating instructions are implemented:

[0173] The three-dimensional coordinates of each point of the cable are collected by a three-dimensional laser, and the three-dimensional coordinates are reduced in dimension to obtain the two-dimensional coordinates of the point;

[0174] Dividing the two-dimensional coordinates of each point into a plurality of point cloud micro-segments, and determining the micro-segment two-dimensional coordinates of each point cloud micro-segment;

[0175] Based on the two-dimensional coordinates of the micro-segment, an objective function is established with a horizontal force component as a parameter to be solved, and a target value of the horizontal force component is obtained by solving the objective function, where the horizontal force component is the component of the cable force of the inclined cable in the horizontal direction;

[0176] The cable force value of the stay cable is determined according to the target value.

[0177] Those skilled in the art will appreciate that all or part of the processes in the above-described embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the above-described embodiments. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct RAM bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM).

[0178] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for identifying cable forces based on three-dimensional point cloud density, characterized in that: include: The three-dimensional coordinates of each point of the cable are collected by a three-dimensional laser, and the three-dimensional coordinates are reduced in dimension to obtain the two-dimensional coordinates of the point; Dividing the two-dimensional coordinates of each point into a plurality of point cloud micro-segments, and determining the micro-segment two-dimensional coordinates of each point cloud micro-segment; Based on the two-dimensional coordinates of the micro-segment, an objective function is established with a horizontal force component as a parameter to be solved, and a target value of the horizontal force component is obtained by solving the objective function, where the horizontal force component is the component of the cable force of the inclined cable in the horizontal direction; Determining the cable force value of the stay cable according to the target value; The determining of the two-dimensional coordinates of each of the point cloud micro-segments includes: Determine a mean of the ordinates corresponding to the two-dimensional ordinates of the points in each of the point cloud micro-segments, where the two-dimensional ordinates of the points are the ordinates included in the two-dimensional ordinates of each point in each of the point cloud micro-segments; For each of the point cloud micro-segments, counting the number of the two-dimensional vertical coordinates of the points that are greater than the mean vertical coordinate, and obtaining the total number of the two-dimensional vertical coordinates of the points contained in each of the point cloud micro-segments; Determining a compensation factor for each of the point cloud micro-segments based on the number and the total number; Correcting the vertical coordinate mean of each point cloud micro-segment according to the compensation factor of each point cloud micro-segment to obtain a vertical coordinate correction value; Determine the mean abscissa value corresponding to the two-dimensional abscissa value within each point cloud micro-segment, and use the ordinate correction value of each point cloud micro-segment and the mean abscissa value of each point cloud micro-segment as the micro-segment two-dimensional coordinate of each point cloud micro-segment; The objective function with the horizontal force component as the parameter to be solved is established based on the two-dimensional coordinates of the micro-segment, including: Based on the mean value of the horizontal coordinate of each point cloud micro-segment, a cable mechanics model is established with the horizontal component as the parameter to be solved, wherein the cable mechanics model includes a catenary cable mechanics model and a parabolic cable mechanics model; Establishing a target sub-function for each point cloud micro-segment according to the cable mechanical model corresponding to each point cloud micro-segment and the vertical coordinate correction value of each point cloud micro-segment; According to the objective sub-function of each point cloud micro-segment, the objective function of the inclined cable with respect to the horizontal component force is obtained.

2. The method for identifying cable forces based on three-dimensional point cloud density according to claim 1, characterized in that: The dimensionality reduction processing of the three-dimensional coordinates to obtain the two-dimensional coordinates of the point includes: Obtaining an upper fixing point and a lower fixing point of the stay cable, wherein the upper fixing point and the lower fixing point are both points for fixing the stay cable, and the upper fixing point is located obliquely above the lower fixing point; Determine the projection point of the upper fixed point on the horizontal plane, and determine a two-dimensional rope-shaped plane formed by the projection point, the lower fixed point, and the upper fixed point, wherein the horizontal plane is the horizontal plane where the lower fixed point is located; Determining a normal vector of the two-dimensional rope-shaped plane and determining a horizontal axis direction vector of a two-dimensional coordinate system with the upper fixed point as a starting point and the lower fixed point as an end point; The three-dimensional coordinates are processed by dimensionality reduction according to the horizontal axis direction vector and the normal vector to obtain the two-dimensional coordinates of the point.

3. The method for identifying cable forces based on three-dimensional point cloud density according to claim 2, wherein: The dimensionality reduction processing of the three-dimensional coordinates according to the horizontal axis direction vector and the normal vector to obtain the two-dimensional coordinates of the point includes: Performing a cross product operation on the horizontal axis direction vector and the normal vector to obtain a vertical axis direction vector of the vertical axis of the two-dimensional coordinate system; The three-dimensional coordinates are subjected to dimensionality reduction processing according to the horizontal axis direction vector and the vertical axis direction vector of the vertical coordinate axis to obtain the two-dimensional coordinates of the point.

4. The method for identifying cable forces based on three-dimensional point cloud density according to claim 1, wherein: Obtaining the target value of the horizontal force component by solving the objective function includes: A quasi-Newton iterative algorithm is applied to the objective function to determine the minimum value of the objective function, and the horizontal component force corresponding to the minimum value is used as the target value.

5. The method for identifying cable force based on three-dimensional point cloud density according to claim 1, characterized in that: Determining the cable force value of the stay cable according to the target value includes: The target value is substituted into the cable mechanics model to obtain the cable force value of the inclined cable.

6. A device for identifying cable force based on three-dimensional point cloud density, characterized in that: The device comprises the following components: A dimensionality reduction module is used to collect the three-dimensional coordinates of each point of the inclined cable through a three-dimensional laser, and perform dimensionality reduction processing on the three-dimensional coordinates to obtain the two-dimensional coordinates of the point; A correction module, configured to divide the two-dimensional coordinates of each point into a plurality of point cloud micro-segments, and determine the two-dimensional coordinates of each point cloud micro-segment; a target value calculation module, configured to establish, based on the two-dimensional coordinates of the micro-segment, an objective function with a horizontal force component as a parameter to be solved, and obtain a target value of the horizontal force component by solving the objective function, wherein the horizontal force component is the component of the cable force of the inclined cable in the horizontal direction; A cable force calculation module, configured to determine the cable force of the stay cable according to the target value; The determining of the two-dimensional coordinates of each of the point cloud micro-segments includes: Determine a mean of the ordinates corresponding to the two-dimensional ordinates of the points in each of the point cloud micro-segments, where the two-dimensional ordinates of the points are the ordinates included in the two-dimensional ordinates of each point in each of the point cloud micro-segments; For each of the point cloud micro-segments, counting the number of the two-dimensional vertical coordinates of the points that are greater than the mean vertical coordinate, and obtaining the total number of the two-dimensional vertical coordinates of the points contained in each of the point cloud micro-segments; Determining a compensation factor for each of the point cloud micro-segments based on the number and the total number; Correcting the vertical coordinate mean of each point cloud micro-segment according to the compensation factor of each point cloud micro-segment to obtain a vertical coordinate correction value; Determine the mean abscissa value corresponding to the two-dimensional abscissa value within each point cloud micro-segment, and use the ordinate correction value of each point cloud micro-segment and the mean abscissa value of each point cloud micro-segment as the micro-segment two-dimensional coordinate of each point cloud micro-segment; The objective function with the horizontal force component as the parameter to be solved is established based on the two-dimensional coordinates of the micro-segment, including: Based on the mean value of the horizontal coordinate of each point cloud micro-segment, a cable mechanics model is established with the horizontal component as the parameter to be solved, wherein the cable mechanics model includes a catenary cable mechanics model and a parabolic cable mechanics model; Establishing a target sub-function for each point cloud micro-segment according to the cable mechanical model corresponding to each point cloud micro-segment and the vertical coordinate correction value of each point cloud micro-segment; According to the objective sub-function of each point cloud micro-segment, the objective function of the inclined cable with respect to the horizontal component force is obtained.

7. A terminal device, characterized in that: The terminal device includes a memory, a processor, and a three-dimensional point cloud density-based inclined-cable force identification program stored in the memory and runnable on the processor. When the processor executes the three-dimensional point cloud density-based inclined-cable force identification program, the steps of the three-dimensional point cloud density-based inclined-cable force identification method as described in any one of claims 1 to 5 are implemented.

8. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a cable-stayed cable force identification program based on three-dimensional point cloud density. When the cable-stayed cable force identification program based on three-dimensional point cloud density is executed by a processor, the steps of the cable-stayed cable force identification method based on three-dimensional point cloud density as described in any one of claims 1 to 5 are implemented.

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