Laser installation deviation angle calibration method for inclination measurement system

Abstract

The invention discloses a laser installation deviation angle calibration method for an inclination measurement system, and relates to an inclination measurement system, and the method is characterized in that the method comprises the following steps: collecting a reference point position; collecting calibration point information: measuring the reference point position from a plurality of non-collinear calibration point positions, and recording data of each calibration point; calculating a laser installation deviation angle: constructing a least square model taking the laser installation deviation angle as an optimization variable based on the data of all the calibration points, and solving an optimal estimation value of the laser installation deviation angle; and S4, calculating the residual error of the laser installation deviation angle according to the optimal estimated value of the laser installation deviation angle, and if the residual error is greater than a preset threshold value, repeating the steps S2 to S4 until the residual error is converged below the preset threshold value, and outputting a final laser installation deviation angle. The method has the advantages of simple and fast operation and high calibration precision.

Description

Technical Field

[0001] The present invention relates to the technical field of tilt measurement systems, and more particularly to a laser installation deviation angle calibration method for tilt measurement systems. Background Art

[0002] The tilt measurement system integrates IMU, laser rangefinder, GNSS RTK, and other devices, and combines them with the pole length to calculate the laser point position in real time. Its core principle is: the IMU obtains attitude information, the laser rangefinder measures distance, and the GNSS RTK provides the pole top coordinates. Ultimately, the laser rangefinder's laser point coordinates are calculated by fusion. The installation deviation angle (heading angle and pitch angle) between the IMU and the laser rangefinder is a key factor affecting measurement accuracy and must be calibrated with high precision. However, existing calibration methods still have the following drawbacks:

[0003] 1. Traditional methods require the assistance of external instruments such as total stations for calibration. For example, the calibration solution based on geometric relationships proposed in patent CN118426005A does not require a total station, but still requires complex environment layout and multi-step operations, resulting in high equipment costs and low calibration efficiency.

[0004] 2. Existing methods mostly calculate the deviation angle based on a single measurement point, which is easily affected by factors such as environmental noise, IMU zero bias, and centering pole shaking, resulting in poor calibration stability.

[0005] 3. Methods that rely on total stations or specific geometric layouts are difficult to implement in complex field scenarios (such as obscured areas and rugged terrain), which seriously restricts the applicability of the project.

[0006] Therefore, a new solution needs to be proposed to solve this problem. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the object of the present invention is to provide a laser installation deviation angle calibration method for a tilt measurement system, which has the advantages of simple and fast operation and high calibration accuracy.

[0008] The above technical objectives of the present invention are achieved through the following technical solutions: A laser installation deviation angle calibration method for a tilt measurement system, comprising the following steps:

[0009] S1, collect the reference point position;

[0010] S2. Collecting calibration point information: measuring the reference point position from multiple non-collinear calibration point positions and recording data of each calibration point;

[0011] S3. Calculate the laser installation deviation angle: Based on the data of all calibration points, construct a least squares model with the laser installation deviation angle as the optimization variable to solve the optimal estimated value of the laser installation deviation angle;

[0012] S4. Convergence judgment of laser installation deviation angle residual: Calculate the laser installation deviation angle residual based on the optimal estimated value of the laser installation deviation angle. If the residual is greater than a preset threshold, repeat steps S2 to S4 until the residual converges to below the preset threshold, and then output the final laser installation deviation angle.

[0013] In one embodiment, the specific method of step S1 is: select a reference point, use the tilt measurement system to collect the position information of the reference point, and record the position of the reference point as The tilt measurement system includes an IMU, a laser rangefinder, a GNSS RTK, and a centering pole. The reference point position is calculated using the attitude cosine matrix of the IMU, the pole top position coordinates obtained by the GNSS RTK, and the length of the centering pole. The reference point position expression is as follows:

[0014]

[0015] in, represents the attitude cosine matrix of the IMU, n represents the local navigation coordinate system, b represents the IMU carrier coordinate system, g represents the position measured by GNSS RTK, and r represents the length of the centering rod.

[0016] In one embodiment, in step S2, the data of each calibration point includes the attitude cosine matrix of the IMU GNSS RTK measurement position coordinates The reference point distance d(k) measured by the laser rangefinder, where k represents the kth calibration point.

[0017] In one embodiment, the specific method of step S3 includes the following steps:

[0018] S31. Define the Euler angles between the laser coordinate system and the IMU carrier coordinate system as the heading angle ψ and the pitch angle θ, and denote the laser coordinate system as l, ignoring the roll angle of the laser coordinate system;

[0019] S32. Construct the rotation matrix from the laser coordinate system to the IMU coordinate system Rotation Matrix is a constant and can be approximated as:

[0020]

[0021] S33, the estimated position of the k-th calibration point relative to the reference point is Based on the rotation matrix IMU attitude cosine matrix GNSS RTK measurement position coordinates And the reference point distance d(k) measured by the laser rangefinder, the following relationship is obtained:

[0022]

[0023] S34. Combine step S33 and the reference point position expression to construct the following optimization objective function:

[0024]

[0025] Among them, ψ * and θ * They represent the optimal estimated value of the heading angle and the optimal estimated value of the pitch angle between the laser coordinate system l and the IMU carrier coordinate system b, respectively. represents the square of the second norm, and k represents the number of calibration points.

[0026] S35, the attitude cosine matrix of IMU Linearize into the following matrix:

[0027]

[0028] The reference point position and the kth calibration point position are linearized into the following matrices:

[0029]

[0030] Among them, x, y, z represent three directions in three-dimensional space;

[0031] S36. Construct the following matrix based on the least squares model:

[0032]

[0033] Then the optimal estimated values of the heading angle and pitch angle between the laser coordinate system l and the IMU carrier coordinate system b are:

[0034]

[0035] in,(·) -1 represents the matrix inversion operation, (·) T Represents the transpose operation of a matrix.

[0036] In one embodiment, after each acquisition of data from a new calibration point, the laser installation deviation angle is calculated based on the data of all current calibration points, that is, the optimal estimated value of the heading angle and the optimal estimated value of the pitch angle between the laser coordinate system l and the IMU carrier coordinate system b are calculated;

[0037] The current laser installation deviation angle residual is calculated according to the following formula, and the laser installation deviation angle residual is recorded as:

[0038]

[0039] Where K is the total number of calibration points collected. When the current laser installation deviation angle residual is less than the preset threshold, the optimal estimated value of the heading angle ψ is * and the optimal estimated value of the pitch angle θ * It is the installation deviation angle between the laser coordinate system and the IMU carrier coordinate system.

[0040] In summary, the present invention has the following beneficial effects: the present invention solves the optimal estimate of the laser installation deviation angle by adopting multiple calibration point positions based on the least squares model, and the calibration can be completed only by conventional measuring equipment, which reduces the equipment cost and has a wider range of applications; the calibration method of the present invention is concise, easy to understand and easy to operate, and effectively weakens the influence of single-point measurement errors by measuring and collecting calibration point information at multiple positions, thereby ensuring that a high-precision estimation result is finally obtained, providing a reliable data basis for subsequent measurement and analysis work. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a flowchart of a laser installation deviation angle calibration method for a tilt measurement system according to an embodiment of the present application;

[0042] Figure 2 This is a schematic diagram of collecting the positions of multiple calibration points in a laser installation deviation angle calibration method for a tilt measurement system according to an embodiment of the present application. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] like Figure 1 and Figure 2 As shown, an embodiment of the present application provides a laser installation deviation angle calibration method for a tilt measurement system, comprising the following steps:

[0045] S1, collect the reference point position;

[0046] S2. Collecting calibration point information: measuring the reference point position from multiple non-collinear calibration point positions and recording data of each calibration point;

[0047] S3. Calculate the laser installation deviation angle: Based on the data of all calibration points, construct a least squares model with the laser installation deviation angle as the optimization variable to solve the optimal estimated value of the laser installation deviation angle;

[0048] S4. Convergence judgment of laser installation deviation angle residual: Calculate the laser installation deviation angle residual based on the optimal estimated value of the laser installation deviation angle. If the residual is greater than a preset threshold, repeat steps S2 to S4 until the residual converges to below the preset threshold, and then output the final laser installation deviation angle.

[0049] It should be noted that the laser installation deviation angle specifically refers to the installation deviation angle between the IMU carrier coordinate system and the laser coordinate system of the laser rangefinder.

[0050] The above method solves the optimal estimate of the laser installation deviation angle by adopting multiple calibration point positions based on the least squares model. The calibration can be completed only by conventional measuring equipment, which reduces the equipment cost and has a wider range of applications. The calibration method of the present invention is simple, easy to understand and easy to operate. By measuring and collecting calibration point information at multiple positions, the influence of single-point measurement errors is effectively weakened, thereby ensuring that a high-precision estimation result is finally obtained, providing a reliable data basis for subsequent measurement and analysis work.

[0051] In this embodiment, the specific method of step S1 is: select a reference point, use the tilt measurement system to collect the position information of the reference point, and record the position of the reference point as The tilt measurement system includes an IMU, a laser rangefinder, a GNSS RTK, and a centering pole. The reference point position is calculated using the attitude cosine matrix of the IMU, the pole top position coordinates obtained by the GNSS RTK, and the length of the centering pole. The reference point position expression is as follows:

[0052]

[0053] in, represents the attitude cosine matrix of the IMU, n represents the local navigation coordinate system, b represents the IMU carrier coordinate system, g represents the position measured by GNSS RTK, and r represents the length of the centering rod.

[0054] In this embodiment, in step S2, the data of each calibration point includes the attitude cosine matrix of the IMU GNSS RTK measurement position coordinates The reference point distance d(k) measured by the laser rangefinder, where k represents the kth calibration point.

[0055] In this embodiment, the specific method of step S3 includes the following steps:

[0056] S31. Define the Euler angles between the laser coordinate system and the IMU carrier coordinate system as the heading angle ψ and the pitch angle θ, and denote the laser coordinate system as l, ignoring the roll angle of the laser coordinate system;

[0057] S32. Construct the rotation matrix from the laser coordinate system to the IMU coordinate system Rotation Matrix is a constant and can be approximated as:

[0058]

[0059] S33, the estimated position of the k-th calibration point relative to the reference point is Based on the rotation matrix IMU attitude cosine matrix GNSS RTK measurement position coordinates And the reference point distance d(k) measured by the laser rangefinder, the following relationship is obtained:

[0060]

[0061] S34. Combine step S33 and the reference point position expression to construct the following optimization objective function:

[0062]

[0063] Among them, ψ * and θ * They represent the optimal estimated value of the heading angle and the optimal estimated value of the pitch angle between the laser coordinate system l and the IMU carrier coordinate system b, respectively. represents the square of the second norm, and k represents the number of calibration points.

[0064] S35, the attitude cosine matrix of IMU Linearize into the following matrix:

[0065]

[0066] The reference point position and the kth calibration point position are linearized into the following matrices:

[0067]

[0068] Among them, x, y, z represent three directions in three-dimensional space;

[0069] S36. Construct the following matrix based on the least squares model:

[0070]

[0071] Then the optimal estimated values of the heading angle and pitch angle between the laser coordinate system l and the IMU carrier coordinate system b are:

[0072]

[0073] in,(·) -1 represents the matrix inversion operation, (·) T Represents the transpose operation of a matrix.

[0074] In this embodiment, after collecting data from each new calibration point, the laser installation deviation angle is calculated based on the data of all current calibration points, that is, the optimal estimated value of the heading angle and the optimal estimated value of the pitch angle between the laser coordinate system l and the IMU carrier coordinate system b are calculated;

[0075] The current laser installation deviation angle residual is calculated according to the following formula, and the laser installation deviation angle residual is recorded as:

[0076]

[0077] Where K is the total number of calibration points collected. When the current laser installation deviation angle residual is less than the preset threshold, the optimal estimated value of the heading angle ψ is * and the optimal estimated value of the pitch angle θ * It is the installation deviation angle between the laser coordinate system and the IMU carrier coordinate system.

[0078] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A laser installation deviation angle calibration method for a tilt measurement system, characterized by: The following steps are involved: S1, collect the reference point position; S2. Collecting calibration point information: measuring the reference point position from multiple non-collinear calibration point positions and recording data of each calibration point; S3. Calculate the laser installation deviation angle: Based on the data of all calibration points, construct a least squares model with the laser installation deviation angle as the optimization variable to solve the optimal estimated value of the laser installation deviation angle; S4. Convergence judgment of laser installation deviation angle residual: Calculate the laser installation deviation angle residual based on the optimal estimated value of the laser installation deviation angle. If the residual is greater than a preset threshold, repeat steps S2 to S4 until the residual converges to below the preset threshold, and then output the final laser installation deviation angle.

2. The laser installation deviation angle calibration method for a tilt measurement system according to claim 1, characterized in that: The specific method of step S1 is: select a reference point, use the tilt measurement system to collect the position information of the reference point, and record the position of the reference point as The tilt measurement system includes an IMU, a laser rangefinder, a GNSS RTK, and a centering pole. The reference point position is calculated using the attitude cosine matrix of the IMU, the pole top position coordinates obtained by the GNSS RTK, and the length of the centering pole. The reference point position expression is as follows: in, represents the attitude cosine matrix of the IMU, n represents the local navigation coordinate system, b represents the IMU carrier coordinate system, g represents the position measured by GNSS RTK, and r represents the length of the centering rod.

3. The laser installation deviation angle calibration method for a tilt measurement system according to claim 2, characterized in that: In step S2, the data of each calibration point includes the attitude cosine matrix of the IMU GNSS RTK measurement position coordinates The reference point distance d(k) measured by the laser rangefinder, where k represents the kth calibration point.

4. The laser installation deviation angle calibration method for a tilt measurement system according to claim 3, characterized in that: The specific method of step S3 includes the following steps: S31. Define the Euler angles between the laser coordinate system and the IMU carrier coordinate system as the heading angle ψ and the pitch angle θ, and denote the laser coordinate system as l, ignoring the roll angle of the laser coordinate system; S32. Construct the rotation matrix from the laser coordinate system to the IMU coordinate system Rotation Matrix is a constant and can be approximated as: S33, the estimated position of the k-th calibration point relative to the reference point is Based on the rotation matrix IMU attitude cosine matrix GNSS RTK measurement position coordinates And the reference point distance d(k) measured by the laser rangefinder, the following relationship is obtained: S34. Combine step S33 and the reference point position expression to construct the following optimization objective function: Among them, ψ * and θ * They represent the optimal estimated value of the heading angle and the optimal estimated value of the pitch angle between the laser coordinate system l and the IMU carrier coordinate system b, respectively. represents the square of the second norm, and k represents the number of calibration points. S35, the attitude cosine matrix of IMU Linearize into the following matrix: Linearize the reference point position and the kth calibration point position into the following matrices: Among them, x, y, z represent three directions in three-dimensional space; S36. Construct the following matrix based on the least squares model: Then the optimal estimated values of the heading angle and pitch angle between the laser coordinate system l and the IMU carrier coordinate system b are: in,(·) -1 represents the matrix inversion operation, (·) T Represents the transpose operation of a matrix.

5. The laser installation deviation angle calibration method for a tilt measurement system according to claim 4, characterized in that: After collecting data from each new calibration point, the laser installation deviation angle is calculated based on the data of all current calibration points, that is, the optimal estimated value of the heading angle and the optimal estimated value of the pitch angle between the laser coordinate system l and the IMU carrier coordinate system b are calculated; The current laser installation deviation angle residual is calculated according to the following formula, and the laser installation deviation angle residual is recorded as: Where K is the total number of calibration points collected. When the current laser installation deviation angle residual is less than the preset threshold, the optimal estimated value of the heading angle ψ is * and the optimal estimated value of the pitch angle θ * It is the installation deviation angle between the laser coordinate system and the IMU carrier coordinate system.

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