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

Abstract

The invention relates to the technical field of stay cable analysis, in particular to a stay cable force identification method, device and equipment based on three-dimensional point cloud density. According to the method, the three-dimensional coordinate of each point on the stay cable is reduced into the point two-dimensional coordinate, then the micro-segment two-dimensional coordinate of each point cloud micro-segment is fitted according to the point two-dimensional coordinate, then the target function about the horizontal component force is established based on the micro-segment two-dimensional coordinate, and the target value of the horizontal component force is obtained by solving the target function. And finally, the cable force value of the stay cable is calculated according to the target value. According to the above analysis, the micro-segment two-dimensional coordinates of each point cloud micro-segment are fitted, the error of the micro-segment two-dimensional coordinates can be reduced, and then the precision of the finally calculated cable force value is improved.

Description

Technical Field

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

[0002] 3D laser scanning technology has a longer range, which not only significantly reduces the risk of high-altitude operations, but also has centimeter or even millimeter-level data accuracy, enabling it to fully capture the three-dimensional shape of the structure. Therefore, 3D laser scanning technology is applied to measure the cable force of the inclined cable (cable force is the tension on the inclined cable, and the inclined cable is the inclined fixed cable). The existing technology obtains the three-dimensional coordinates of each point on the inclined cable through the three-dimensional laser scanning technology, fits the cable centerline through each three-dimensional coordinate, and solves the cable force through the cable centerline. Since fitting the centerline through each three-dimensional coordinate will reduce the accuracy of the centerline, it will reduce the accuracy of the solved cable force.

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

[0004] Therefore, the prior art still 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 the cable force of a inclined cable based on three-dimensional point cloud density, which solves the problem that the existing technology reduces the accuracy of the solved cable force.

[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 the cable force of a stay cable based on three-dimensional point cloud density, which comprises:

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

[0009] Divide the two-dimensional coordinates of each point into a plurality of point cloud micro-segments, and determine 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 with a horizontal force component as a parameter to be solved is established, and a target value of the horizontal force component is obtained by solving the objective function, wherein the horizontal force component is a component of the cable force of the inclined cable in the horizontal direction;

[0011] The cable force value of the inclined 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 inclined cable, wherein the upper fixing point and the lower fixing point are points used to fix the inclined 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 the 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] Determine the normal vector of the two-dimensional rope-shaped plane, and determine the horizontal axis direction vector of the two-dimensional coordinate system with the upper fixed point as the starting point and the lower fixed point as the end point;

[0016] The three-dimensional coordinates are reduced in dimension 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 according to 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 reduced in dimension 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 micro-segment two-dimensional coordinates of each of the point cloud micro-segments includes:

[0021] Determine a mean value of the ordinates corresponding to the two-dimensional ordinates of the points in each of the point cloud micro-segments, wherein 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 point two-dimensional ordinates greater than the mean value of the ordinates, and obtaining the total number of the point two-dimensional ordinates contained in each of the point cloud micro-segments;

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

[0024] According to the compensation factor of each point cloud micro-segment, correct the mean value of the ordinate of each point cloud micro-segment to obtain a corrected ordinate value;

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

[0026] In one implementation, 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:

[0027] Based on the mean value of the horizontal coordinate of each point cloud micro-segment, a cable mechanics model with the horizontal component as the parameter to be solved is established, wherein the cable mechanics model includes a catenary cable mechanics model and a parabola 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 ordinate 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 of a stay cable based on three-dimensional point cloud density, wherein the device comprises the following components:

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

[0036] A correction module, used for 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;

[0037] A target value calculation module is used 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, wherein the horizontal force component is a component of the cable force of the inclined cable in the horizontal direction;

[0038] The cable force value 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 comprises a memory, a processor, and a cable-force identification program based on three-dimensional point cloud density stored in the memory and executable on the processor, and when the processor executes the cable-force identification program based on three-dimensional point cloud density, the steps of the above-mentioned 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-force identification program based on three-dimensional point cloud density. When the cable-force identification program based on three-dimensional point cloud density is executed by a processor, the steps of the above-mentioned cable-force identification method based on three-dimensional point cloud density are implemented.

[0041] Beneficial effects: The present invention reduces the dimensionality of the three-dimensional coordinates of each point on the inclined cable to the two-dimensional coordinates of the point, and then fits the two-dimensional coordinates of each micro-segment of the point cloud according to the two-dimensional coordinates of the point, and then establishes an objective function for the horizontal force component based on the two-dimensional coordinates of the micro-segment, and obtains the target value of the horizontal force component by solving the objective function, and finally calculates the cable force value of the inclined cable by using the target value. Through the above analysis, it can be seen that the present invention fits the two-dimensional coordinates of the micro-segment of each point cloud micro-segment, which can reduce the error of the two-dimensional coordinates of the micro-segment, thereby improving the accuracy of the cable force value finally calculated. 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 is a 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 a 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 is a flow chart for identifying cable force in an embodiment of the present invention;

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

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

[0051] The following is a clear and complete description of the technical solution of the present invention in combination 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 creative work are within the scope of protection of the present invention.

[0052] Research has found that 3D laser scanning technology has a longer range, which not only significantly reduces the risk of high-altitude operations, but also has centimeter or even millimeter-level data accuracy, enabling it to fully capture the three-dimensional shape of the structure. Therefore, 3D laser scanning technology is applied to measure the cable force of the inclined cable (cable force is the tension on the inclined cable, and the inclined cable is the inclined fixed cable). The existing technology obtains the three-dimensional coordinates of each point on the inclined cable through 3D laser scanning technology, fits the cable centerline through each 3D coordinate, and solves the cable force through the cable centerline. Since fitting the centerline through each 3D coordinate will reduce the accuracy of the centerline, it will reduce the accuracy of the solved cable force.

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

[0054] The cable force identification method based on three-dimensional 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 method for identifying the cable force of a stay cable 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 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 micro-segment 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, wherein the horizontal force component is a 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] Embodiment 1, in this embodiment, as Figure 2 As shown, the laser transmitter is fixed at point B on the horizontal plane, and the arc is a stay cable, point A is the lower end point of the stay cable, point O is the upper end point of the stay cable, and the projection of point O on the horizontal plane is B, and 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 at point O and upward is the positive direction of the z-axis of the three-dimensional coordinate system. The three-dimensional coordinates of each point on the stay cable are collected by the laser emitted by the laser transmitter in the three-dimensional coordinate system. In this embodiment, step S100 includes the following specific steps S101 to S105:

[0060] S101, obtaining an upper fixing point O and a 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 direction vector of the vertical axis y of the two-dimensional coordinate system.

[0066]

[0067] S105, based on the horizontal axis direction vector and the longitudinal direction vector of the longitudinal axis The three-dimensional coordinates are processed by dimensionality reduction 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 vector in the vertical direction is the y-axis of the two-dimensional coordinate system. The three-dimensional coordinates (x k ,y k ,z k ) is used for dimensionality reduction to 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 a two-dimensional point cloud coordinate set D.

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

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

[0074] Step S100 obtains a two-dimensional point cloud coordinate set D, divides the point cloud data into N point cloud micro-segments according to the horizontal coordinate range of the point cloud, and the point cloud set S of the mth point cloud micro-segment 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 mth 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 coordinates 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 coordinates of the first point to the horizontal coordinates of the fifth point and the vertical coordinates of the first point to the vertical coordinates of the fifth point; the second point cloud micro-segment includes the horizontal coordinates of the sixth point to the horizontal coordinates of the tenth point and the vertical coordinates of the sixth point to the vertical coordinates of the tenth point; the third point cloud micro-segment includes the horizontal coordinates of the eleventh point to the horizontal coordinates of the fifteenth point and the vertical coordinates of the eleventh point to the vertical coordinates of the fifteenth point; the fourth point cloud micro-segment includes the horizontal coordinates of the sixteenth point to the horizontal coordinates of the twentieth point and the vertical coordinates of the sixteenth point to the vertical coordinates of the twentieth point. For the first point cloud micro-segment, the sum of the vertical coordinates of the first point plus the vertical coordinates of the second point plus the vertical coordinates of the third point plus the vertical coordinates of the fourth point plus the vertical coordinates of the fifth point divided by five is the average of the two-dimensional vertical coordinates of the points of the first point cloud micro-segment.

[0081] S202, for each of the point cloud micro-segments, count the number of the point two-dimensional ordinates greater than the mean value of the ordinates, and obtain the total number S of the point two-dimensional ordinates contained in each of the point cloud micro-segments m .

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

[0083] S202 and S203 are illustrated by taking the mth point cloud micro-segment as an example.

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

[0085]

[0086] In the formula, Meaning: when yi Greater than or equal to When , 1 is accumulated, that is, It is the number of points in the m-th point cloud micro-segment whose two-dimensional ordinate coordinates are greater than the mean (that is, the number of points in the m-th point cloud micro-segment whose two-dimensional ordinate coordinates are greater than the mean).

[0087] After projecting the 3D point cloud data onto the 2D cable-shaped plane, it is necessary to extract the center line of the 2D plane projection point to characterize the cable shape. However, when using 3D laser scanning technology to obtain point cloud data, due to the influence of factors such as ambient lighting, surface reflectivity, occlusion, scanning angle and scanning distance, the point cloud density of the same cable at different cross-sectional positions often varies, that is, there is an error in the 2D coordinates after dimensionality reduction. This embodiment eliminates the error through a compensation factor, thereby improving the accuracy of the 2D coordinates used for cable force calculation.

[0088] S204: Correct the vertical coordinate mean value 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 ordinate 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 And 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 micro-segment 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, 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 in the equation is an unknown parameter. Cable mechanics model Includes catenary cable mechanics model or parabola cable mechanics model.

[0097] When the cable mechanical model is a catenary cable mechanical 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 m-th point cloud micro-segment in the vertical direction, and q is the cable weight of the m-th point cloud micro-segment.

[0098] Among them, the θ involved in the catenary cable mechanical model 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] Substituting 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 force of the catenary cable:

[0104]

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

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

[0107]

[0108] In the formula, represents the angle between the chord between the two endpoints of the mth 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, the horizontal component force H of the cable is a constant. By subdividing the cable into micro-segmented mechanical equilibrium equations, we can obtain:

[0113]

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

[0115]

[0116] Integrate the above equation twice and replace the boundary conditions (0, 0) and (l i ,h i ) into the equation, we 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 vertical angle of the parabola must be at the mid-span point, and thus:

[0123]

[0124] right Taking the derivative, we can get θ x .

[0125] S302, 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 ordinate correction value of each point cloud micro-segment:

[0126]

[0127] S303, based on the target sub-function of each point cloud micro-segment The objective function E(H) of the inclined cable with respect to the horizontal component force is obtained.

[0128]

[0129] In this embodiment, the expression of E(H) is derived based on the following derivation: The two-dimensional linear point set {x i ,y i}, based on the two-dimensional linear point set {x i ,y i} is fitted to a catenary or parabola. i ,y i The following regression equation can be established to solve the horizontal component H of the cable:

[0130] y=f(x,H)+ε

[0131] Where ε is the error of the regression model, that is, the two-dimensional linear point set {x i ,y i} and the difference between the theoretical linear model (catenary model, parabola model). Input the initial value H0 of the horizontal component of the cable force, perform Taylor expansion of equation (5-25) at H0 and take the first two order expansions to obtain:

[0132]

[0133] Then calculate the measured cable shape precise point set for the selected

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

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

[0136] middle, and As m and N are both known, H is an unknown quantity, that is, H is the parameter that needs to be solved. Each point cloud micro-segment has an H that needs to be solved, that is, 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 unit 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] In the formula, is the gradient of function f with respect to H.

[0143] Use the inverse of the Hessian matrix of the current approximation B k Compute the search direction:

[0144]

[0145] Line search: Determine the 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 k :

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

[0151]

[0152] Update the Hessian matrix approximation:

[0153] Use the difference vector s k and 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] Embodiment 4, based on embodiment 1 or embodiment 2 or embodiment 3, in this embodiment, 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 mth point cloud micro-segment.

[0164] In summary, the present invention realizes a non-invasive cable force measurement with high recognition accuracy and practicality. The high-precision geometric data obtained by laser scanning, such as the spatial sag, inclination, cable length, etc. of the cable, can provide reliable parameters for the existing practical formulas for calculating cable force. The present invention avoids the challenges of service life limitation, high maintenance cost, and frequency data reliability that may be faced when using sensors, and provides a more reliable and economical way for cable force identification.

[0165] This embodiment also provides a device for identifying the cable force of a stay cable based on the density of a three-dimensional point cloud. Figure 8 As shown, the device comprises 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 micro-segment two-dimensional coordinates of each point cloud micro-segment;

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

[0169] The cable force value 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 embodiments, the present invention further provides a terminal device, whose principle block diagram can be shown as follows: Fig. 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 the cable force of a cable based on three-dimensional point cloud density is implemented. The display screen of the terminal device can be a liquid crystal display screen or an electronic ink display screen.

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

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

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

[0174] Divide the two-dimensional coordinates of each point into a plurality of point cloud micro-segments, and determine 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 with a horizontal force component as a parameter to be solved is established, and a target value of the horizontal force component is obtained by solving the objective function, wherein the horizontal force component is a component of the cable force of the inclined cable in the horizontal direction;

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

[0177] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. 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. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus 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 embodiments of the present invention.

Claims

1. A method for identifying cable force based on three-dimensional point cloud density, characterized in that: include: The three-dimensional coordinates of each point of the cable are collected by three-dimensional laser, and the three-dimensional coordinates are reduced in dimension to obtain the two-dimensional coordinates of the point; Divide the two-dimensional coordinates of each point into a plurality of point cloud micro-segments, and determine 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 with a horizontal force component as a parameter to be solved is established, and a target value of the horizontal force component is obtained by solving the objective function, wherein the horizontal force component is a component of the cable force of the inclined cable in the horizontal direction; The cable force value of the inclined cable is determined according to the target value.

2. The method for identifying the cable force of a stay cable 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 inclined cable, wherein the upper fixing point and the lower fixing point are points used to fix the inclined 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 the 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; Determine the normal vector of the two-dimensional rope-shaped plane, and determine the horizontal axis direction vector of the two-dimensional coordinate system with the upper fixed point as the starting point and the lower fixed point as the end point; The three-dimensional coordinates are reduced in dimension 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 the cable force of a stay cable based on three-dimensional point cloud density according to claim 2, characterized in that: 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 reduced in dimension 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 the cable force of a stay cable based on three-dimensional point cloud density according to claim 1, characterized in that: The determining of the micro-segment two-dimensional coordinates of each of the point cloud micro-segments includes: Determine a mean value of the ordinates corresponding to the two-dimensional ordinates of the points in each of the point cloud micro-segments, wherein 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 point two-dimensional ordinates greater than the mean value of the ordinates, and obtaining the total number of the point two-dimensional ordinates contained in each of the point cloud micro-segments; Determining a compensation factor for each of the point cloud micro-segments according to the number and the total number; According to the compensation factor of each point cloud micro-segment, correct the ordinate mean of each point cloud micro-segment to obtain a ordinate correction value; The mean value of the horizontal coordinates corresponding to the two-dimensional horizontal coordinates in each of the point cloud micro-segments is determined, and the vertical coordinate correction value of each of the point cloud micro-segments and the mean value of the horizontal coordinates of each of the point cloud micro-segments are used as the micro-segment two-dimensional coordinates of each of the point cloud micro-segments.

5. The method for identifying the cable force of a stay cable based on three-dimensional point cloud density according to claim 4, characterized in that: 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 with the horizontal component as the parameter to be solved is established, wherein the cable mechanics model includes a catenary cable mechanics model and a parabola 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 ordinate 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.

6. The method for identifying the cable force of a stay cable based on three-dimensional point cloud density according to claim 1, characterized in that: The step of 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.

7. The method for identifying the cable force of a stay cable based on three-dimensional point cloud density according to claim 5, 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.

8. A device for identifying the force of a stay cable based on three-dimensional point cloud density, characterized in that: The device comprises the following components: A dimension reduction module is used to collect the three-dimensional coordinates of each point of the inclined cable through a three-dimensional laser, and perform dimension reduction processing on the three-dimensional coordinates to obtain the two-dimensional coordinates of the point; A correction module, used for 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; A target value calculation module is used 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, wherein the horizontal force component is a component of the cable force of the inclined cable in the horizontal direction; The cable force value calculation module is used to determine the cable force value of the inclined cable according to the target value.

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

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a cable-force identification program based on three-dimensional point cloud density. When the cable-force identification program based on three-dimensional point cloud density is executed by a processor, the steps of the cable-force identification method based on three-dimensional point cloud density as described in any one of claims 1 to 7 are implemented.

Images