A split design magnetic north pole measuring three-dimensional compass

Abstract

The application provides a split type magnetic north pole measuring three-dimensional compass, which comprises a first mounting reference surface, an acceleration acquisition and operation circuit board, a double-head terminal wire, a second mounting reference surface and a magnetic force probe circuit board, the acceleration acquisition and operation circuit board is arranged on the first mounting reference surface, the magnetic force probe circuit board is arranged on the second mounting reference surface, and the acceleration acquisition and operation circuit board is connected to the magnetic force probe circuit board through the double-head terminal wire; wherein the space calibration process of the magnetic force probe circuit board comprises the following steps: step S1, constructing an ellipsoid equation; step S2, obtaining a coefficient matrix corresponding to the ellipsoid equation; step S3, calculating an ellipsoid center offset as a fixed zero point of magnetic field interference; and step S4, obtaining eigenvalues after a decomposition matrix according to the fixed zero point, and calculating a scale coefficient matrix. The application can improve the measurement precision of the product and reduce the limitation of the product on the installation environment.

Description

Technical Field

[0001] This invention relates to a three-dimensional electronic compass, and more particularly to a three-dimensional magnetic north pole measuring compass with a split design. Background Technology

[0002] A three-dimensional electronic compass, also known as a three-dimensional digital compass, or simply a three-dimensional compass, typically consists of an integrated triaxial accelerometer and a triaxial magnetometer. The accelerometer measures the specific force of a carrier, defined as the non-gravitational force per unit mass; the magnetometer measures the intensity of the magnetic field sensed in the carrier's coordinate system. As a navigation instrument or attitude sensor, the three-dimensional compass, when installed as a whole, can be applied in fields such as marine navigation and surveying, GPS integrated navigation, antenna servo control, infrared imagers, laser rangefinders, map plotters, underwater robot navigation, oceanographic surveying instruments, and robots for special applications. In the actual application environment of a three-dimensional compass, the Earth's magnetic field is the natural reference field, pointing from the geographic South Pole to the geographic North Pole, with a strength of approximately 0.5–0.6 Gauss, indicating a relatively weak magnetic field. The geomagnetic axis does not coincide with the Earth's rotation axis, exhibiting a tilt angle of approximately 11.5°, known as magnetic declination. In China, this declination is typically 1–5°, but can reach a maximum of 11°, thus introducing a certain degree of error into actual measurements. Furthermore, the unavoidable presence of various interference sources in actual installation environments means that existing 3D compasses cannot adequately meet practical anti-interference requirements, resulting in significant limitations in terms of installation environment and hindering product promotion and application. Therefore, optimizing the structure and spatial calibration process of the 3D compass is undoubtedly a crucial technical problem that must be solved for magnetic north pole measurement using a 3D compass, in order to effectively improve the product's measurement accuracy and reduce its limitations in the installation environment. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a split-type magnetic north pole measuring three-dimensional compass, which aims to improve the measurement accuracy of the product and reduce the limitations of the product on the installation environment by optimizing the structure and spatial calibration process of the three-dimensional compass.

[0004] To address this, the present invention provides a split-type three-dimensional magnetic north pole measurement compass, comprising: a first mounting reference surface, an acceleration acquisition and processing circuit board, a dual-ended terminal wire, a second mounting reference surface, and a magnetic probe circuit board. The acceleration acquisition and processing circuit board is disposed on the first mounting reference surface, and the magnetic probe circuit board is disposed on the second mounting reference surface. The acceleration acquisition and processing circuit board is connected to the magnetic probe circuit board via the dual-ended terminal wire. The spatial calibration process of the magnetic probe circuit board includes the following steps:

[0005] Step S1: Construct the ellipsoid equation for the magnetic field model of the magnetic probe circuit board;

[0006] Step S2: Obtain the coefficient matrix corresponding to the ellipsoid equation based on the sampling point data at the calibration position;

[0007] Step S3: Calculate the ellipsoid center offset based on the coefficients of the ellipsoid equation, and use the ellipsoid center offset as the fixed zero point of the magnetic field interference of the magnetic probe circuit board.

[0008] Step S4: Obtain the eigenvalues ​​of the decomposed matrix based on the fixed zero point of the magnetic field interference, and calculate the scale coefficient matrix of the magnetic probe circuit board based on the eigenvalues.

[0009] A further improvement of the present invention is that, in step S1, the formula Ax is used. 2 +By 2 +Cz 2 +2Dxy+2Exz+2Fyz+2Gx+2Hy+2Iz=1 An ellipsoidal equation is constructed for the magnetic field model of the magnetic probe circuit board, where A, B, C, D, E, F, G, H and I represent the nine coefficients of the ellipsoidal equation, and x, y and z represent the coordinates of the triaxial magnetometer in the magnetic probe circuit board.

[0010] A further improvement of the present invention is that step S2 includes the following sub-steps:

[0011] Step S201, using the formula Hk = [x 2 ,y 2 ,z 2 ,2xy,2xz,2yz,2x,2y,2z] 12×9 Calculate matrix Hk, where Hk represents a 12×9 matrix;

[0012] Step S202, using the formula Xk=(Hk) T *Hk) T *Hk T *Yk calculates the coefficient matrix Xk, where Xk represents a 9×1 coefficient matrix, corresponding to the nine coefficients A, B, C, D, E, F, G, H, and I; the superscript T indicates the transpose matrix; Yk represents a 12×1 first-order matrix, used to represent the sampling point data at the twelve calibration positions.

[0013] A further improvement of the present invention is that, in step S202, the sampling of the twelve calibration positions includes:

[0014] First calibration position: horizontal placement, stationary sampling in any direction;

[0015] The second calibration position is placed horizontally, rotated 90° clockwise relative to the first calibration position, and then sampled at rest.

[0016] The third calibration position is placed horizontally, rotated 90° clockwise relative to the second calibration position, and then sampled at rest.

[0017] The fourth calibration position is placed horizontally, rotated 90° clockwise relative to the third calibration position, and then sampled at rest.

[0018] At the fifth calibration position, after rotating 30° clockwise relative to the fourth calibration position, adjust the pitch angle to 45°±10° and perform static sampling.

[0019] At the sixth calibration position, maintain the pitch angle of the fifth calibration position, rotate 90° clockwise relative to the fifth calibration position, and then sample at rest;

[0020] At the seventh calibration position, maintain the pitch angle of the sixth calibration position, rotate 90° clockwise relative to the sixth calibration position, and then sample from a stationary position.

[0021] At the eighth calibration position, maintain the pitch angle of the seventh calibration position, rotate 90° clockwise relative to the seventh calibration position, and then sample at rest;

[0022] At the ninth calibration position, rotate 30° clockwise relative to the eighth calibration position, then adjust the pitch angle to -45°±10° and perform stationary sampling.

[0023] At the tenth calibration position, maintain the pitch angle of the ninth calibration position, rotate 90° clockwise relative to the ninth calibration position, and then sample at rest;

[0024] At the eleventh calibration position, maintain the pitch angle of the tenth calibration position, rotate 90° clockwise relative to the tenth calibration position, and then sample at rest.

[0025] At the twelfth calibration position, maintain the pitch angle of the eleventh calibration position, rotate 90° clockwise relative to the eleventh calibration position, and then sample at rest.

[0026] A further improvement of the present invention is that the sampling point adjustment process of the twelve calibration positions is realized by a tripod turntable and an indexing plate, and the magnetic probe circuit board is set on the tripod turntable through the indexing plate; during the rotation of the angle, the angle error is controlled within 5 to 10°.

[0027] A further improvement of the present invention is that step S3 is performed using a formula. The coefficients of the ellipsoid equation are calculated to determine the ellipsoid center offset (Center), and this ellipsoid center offset (Center) is used as the fixed zero point for the magnetic field interference of the magnetic probe circuit board.

[0028] A further improvement of the present invention is that step S4 includes the following sub-steps:

[0029] Step S401, using the formula The eigenvalues ​​Mat_r after decomposition are obtained, where Center(1:3) represents the first to third vector elements in the ellipsoid center offset Center, and 1:3 represents the numbers 1 to 3.

[0030] Step S402, using the formula Calculate the ellipsoidal axis length Radii of the magnetic field model, where RD represents a diagonal matrix composed of eigenvalues ​​Mat_r, and RD(i) represents the eigenvalue elements; i is a natural number from 1 to 3;

[0031] Step S403: Take the minimum value of the ellipsoid axis length Radi using the formula min_Radii = min(Radii);

[0032] Step S404, using the formula The minimum axis length min_Radii is normalized by the scale coefficient to obtain the normalized scale coefficient Scale, where Radii(i) represents the ellipsoid axis length;

[0033] Step S405, using the formula mat_Correct = RV * Scale * RV T Calculate the scale coefficient matrix mat_Correct of the magnetic probe circuit board, where RV represents the matrix composed of the eigenvectors corresponding to the eigenvalues ​​Mat_r.

[0034] A further improvement of the present invention is that the distance between the installation position of the second mounting reference surface and the magnetic medium object is controlled to be more than 40cm, wherein the magnetic medium object includes any one or more of iron, magnet and engine.

[0035] A further improvement of the present invention is that when the distance between the installation position of the second mounting reference surface and the magnetic medium object is less than 40cm, after fixing the second mounting reference surface and the magnetic medium object, the magnetic probe circuit board and the magnetic medium object are controlled to perform synchronous rotation calibration.

[0036] A further improvement of the present invention is that the installation angles of the acceleration acquisition and calculation circuit board and the magnetic probe circuit board are defined as follows: the azimuth angle refers to the X-axis direction, the measurement range is 0° to 360°, 0° is when pointing to magnetic north, and clockwise rotation is positive; the pitch angle refers to the Y-axis direction, the measurement range is -90° to 90°, 0° is when horizontal, upward tilt is positive, and downward tilt is negative; the roll angle refers to the Z-axis direction, the measurement range is -180° to 180°, 0° is when horizontal, right tilt is positive, and left tilt is negative.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows: A separate design between the acceleration acquisition and calculation circuit board and the magnetic probe circuit board is achieved through the first mounting reference surface, the second mounting reference surface, and the dual-ended terminal wire. An optimized spatial calibration process for the magnetic probe circuit board is also provided. This not only allows the magnetic probe circuit board to be smaller in size, facilitating its installation in any space with a good magnetic field environment for magnetic data acquisition, but also enables the acceleration acquisition and calculation circuit board to be installed in any environment, effectively reducing limitations on the installation environment. Furthermore, the optimized spatial calibration process provides a good foundation for improving the measurement accuracy of the product, facilitating its promotion and application. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of one embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of the spatial calibration process of a magnetic probe circuit board according to an embodiment of the present invention;

[0040] Figure 3 This is a schematic diagram of the sampling arrangement of twelve calibration positions according to an embodiment of the present invention;

[0041] Figure 4 This is a schematic diagram illustrating the installation angle definition of one embodiment of the present invention. Detailed Implementation

[0042] In the description of this invention, if directional descriptions are involved, such as "up," "down," "front," "back," "left," "right," etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, it is only for the convenience of describing the invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. If a technical feature is referred to as "set," "fixed," "connected," or "installed" on another technical feature, it can be directly set, fixed, or connected to the other technical feature, or it can be indirectly set, fixed, connected, or installed on the other technical feature.

[0043] In the description of this invention, the term "several" means one or more; the term "multiple" means two or more; the terms "greater than," "less than," and "exceeding" are all understood to exclude the stated number; and the terms "above," "below," and "within" are all understood to include the stated number. The terms "first," "second," etc., are understood to be used only to distinguish identical or similar technical feature names, and should not be construed as implying / indicating the relative importance of the technical features, the number of technical features, or the sequential relationship between the technical features.

[0044] The preferred embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.

[0045] like Figures 1 to 4 As shown, this embodiment provides a split-type magnetic north pole measurement three-dimensional compass, including: a first mounting reference surface 1, an acceleration acquisition and processing circuit board 3, a dual-ended terminal wire 5, a second mounting reference surface 7, and a magnetic probe circuit board 9. The acceleration acquisition and processing circuit board 3 is disposed on the first mounting reference surface 1, and the magnetic probe circuit board 9 is disposed on the second mounting reference surface 7. The acceleration acquisition and processing circuit board 3 is connected to the magnetic probe circuit board 9 through the dual-ended terminal wire 5. The spatial calibration process of the magnetic probe circuit board 9 includes the following steps:

[0046] Step S1: Construct the ellipsoid equation for the magnetic field model of the magnetic probe circuit board 9;

[0047] Step S2: Obtain the coefficient matrix corresponding to the ellipsoid equation based on the sampling point data at the calibration position;

[0048] Step S3: Calculate the ellipsoid center offset based on the coefficients of the ellipsoid equation, and use the ellipsoid center offset as the fixed zero point of the magnetic field interference of the magnetic probe circuit board 9.

[0049] Step S4: Obtain the eigenvalues ​​of the decomposed matrix based on the fixed zero point of the magnetic field interference, and calculate the scale coefficient matrix of the magnetic probe circuit board 9 based on the eigenvalues.

[0050] like Figure 1As shown, in this embodiment, the first mounting reference surface 1 is preferably provided with mounting holes 2. The first mounting reference surface 1 is installed and fixed through the mounting holes 2 and the first brass screw 4. The acceleration acquisition and calculation circuit board 3 refers to the main circuit board used to realize acceleration acquisition and calculation, and is preferably an HCM603 circuit board. The double-ended terminal wire 5 is preferably an NH1.0-6PIN double-ended terminal wire. The second mounting reference surface 7 is preferably provided with mounting holes 6. The second mounting reference surface 7 is installed and fixed through the mounting holes 6 and the second brass screw 8. In order to ensure the measurement accuracy of the product, the first brass screw 4 and the second brass screw 8 are preferably M2 non-magnetic screws, such as M2 brass screws, during installation. The magnetic probe circuit board 9 refers to the magnetometer circuit board used to realize magnetic detection and calibration, and is preferably an HM65 circuit board.

[0051] The magnetic north pole measurement three-dimensional compass provided in this embodiment refers to a high-precision three-dimensional electronic compass with separate measurement. To solve the problem of uncertain magnetic field interference in the user equipment environment, a technical solution of separating the magnetic probe circuit board 9 (hereinafter referred to as the magnetic probe) and the acceleration acquisition and calculation circuit board 3 (hereinafter referred to as the acquisition and calculation circuit or acquisition board) is adopted. The two modules, the magnetic probe circuit board 9 and the acceleration acquisition and calculation circuit board 3, are connected and transmit signals through a double-ended terminal wire 5 and its cable. Since the magnetic probe circuit board 9 (hereinafter referred to as the magnetic probe) is small in size, it can be easily installed in any space with a good magnetic field environment to collect magnetic data; while the acceleration acquisition and calculation circuit board 3 (hereinafter referred to as the acquisition and calculation circuit or acquisition board) can be installed in any environment.

[0052] The magnetic probe circuit board 9 described in this embodiment employs a hardware circuit board (also known as hard magnet) and software spatial calibration (also known as soft magnetic calibration algorithm), enabling the product to eliminate the influence of magnetic fields even in environments with magnetic interference through the accompanying spatial calibration process. This embodiment integrates triaxial magnetic sensing technology, using a central processing unit to calculate heading in real time and a triaxial accelerometer to compensate for heading over a wide range of tilt angles, ensuring the compass provides high-accuracy heading data even at tilt angles up to ±85°. This embodiment integrates high-precision MCU control with diverse output methods, including standard interfaces such as RS232 / RS485 / TTL, and can also accept customized communication interfaces.

[0053] In addition, this embodiment is characterized by its small size and low power consumption, and can be applied in many fields such as antenna stabilization, vehicles and system integration. It has high shock resistance and high reliability, which enables the three-dimensional compass to work normally in extremely harsh environments, making it more suitable for today's various high-precision measurement and integrated control systems.

[0054] It should be noted that this embodiment is not intended to compensate for or change the magnetic interference of the installation environment, but rather to optimize the design of the structure and spatial calibration process of the three-dimensional compass, so as to calculate a suitable deviation in a stable magnetic environment, thereby providing an accurate data basis for deviation compensation.

[0055] More specifically, in step S1 of this embodiment, the formula Ax is used. 2 +By 2 +Cz 2 +2Dxy+2Exz+2Fyz+2Gx+2Hy+2Iz=1 An ellipsoidal equation is constructed for the magnetic field model of the magnetic probe circuit board 9, where A, B, C, D, E, F, G, H, and I represent the nine polynomial coefficients of the ellipsoidal equation, and x, y, and z represent the three-dimensional coordinates of the triaxial magnetometer in the magnetic probe circuit board 9. The ellipsoidal equation model is a quadratic ternary polynomial structure, and A, B, C, D, E, F, G, H, and I are the polynomial coefficients of the ellipsoidal equation.

[0056] In this embodiment, the data from the sampling points at the twelve calibration locations are preferably substituted into the formula Ax. 2 +By 2 +Cz 2 +2Dxy+2Exz+2Fyz+2Gx+2Hy+2Iz=1 can be written in the form of a matrix equation: Yk=Hk*Xk, where Yk represents a 12×1 first-order sampling matrix, Xk represents a 9×1 ellipsoidal coefficient matrix corresponding to the nine coefficients A~I, and Hk represents a 12×9 ellipsoidal sampling matrix.

[0057] Step S2 in this embodiment includes the following sub-steps:

[0058] Step S201, using the formula Hk = [x 2 ,y 2 ,z 2 ,2xy,2xz,2yz,2x,2y,2z] 12×9 Calculate matrix Hk, where Hk represents a 12×9 matrix;

[0059] Step S202, using the formula Xk=(Hk) T *Hk) T *Hk T *Yk calculates the coefficient matrix Xk, where Xk represents a 9×1 ellipsoidal coefficient matrix, used to correspond to the nine coefficients A, B, C, D, E, F, G, H, and I; the superscript T indicates the transpose matrix; Yk represents a 12×1 first-order matrix, used to represent the sampling point data at the twelve calibration positions.

[0060] In practical applications, the coefficients in the coefficient matrix Xk can be calculated using the least squares method. To ensure real-time performance, the recursive least squares method can also be used.

[0061] Specifically, such as Figure 3 As shown, in step S202 of this embodiment, the sampling of the twelve calibration positions includes:

[0062] The first calibration position, i.e. Figure 3 The top view position 1 shown is horizontally placed and stationary for sampling in any direction; at this time, the azimuth angle of the magnetic north pole measuring three-dimensional compass points to 0°, the pitch angle is 0°, and the roll angle is 0°.

[0063] The second calibration position, i.e. Figure 3 The top view position 2 shown is horizontally placed and rotated 90° clockwise relative to the first calibration position before being stationary for sampling; at this time, the azimuth angle of the magnetic north pole measuring three-dimensional compass points to 90°, the pitch angle is 0°, and the roll angle is 0°.

[0064] The third calibration position, i.e. Figure 3 The top view position 3 shown is horizontally placed and rotated 90° clockwise relative to the second calibration position before being stationary for sampling; at this time, the azimuth angle of the magnetic north pole measuring three-dimensional compass points to 180°, the pitch angle is 0°, and the roll angle is 0°.

[0065] The fourth calibration position, namely Figure 3 The top view position 4 shown is horizontally placed and rotated 90° clockwise relative to the third calibration position before being stationary for sampling; at this time, the azimuth angle of the magnetic north pole measuring three-dimensional compass points to 270°, the pitch angle is 0°, and the roll angle is 0°.

[0066] The fifth calibration position, namely Figure 3 The top view position 5 shown is rotated 30° clockwise relative to the fourth calibration position, and the pitch angle is adjusted to 45°±10° for stationary sampling. At this time, the azimuth angle of the magnetic north pole measuring three-dimensional compass is 30°, the pitch angle is 45°, and the roll angle is 0°.

[0067] The sixth calibration position, namely Figure 3 In the top view position 6 shown, the pitch angle of the fifth calibration position is maintained. After rotating 90° clockwise relative to the fifth calibration position, the sample is taken at rest. At this time, the azimuth angle of the magnetic north pole measuring three-dimensional compass is 120°, the pitch angle is 45°, and the roll angle is 0°.

[0068] The seventh calibration position, namely Figure 3In the top view position 7 shown, the pitch angle of the sixth calibration position is maintained. After rotating 90° clockwise relative to the sixth calibration position, the sample is taken at rest. At this time, the azimuth angle of the magnetic north pole measuring three-dimensional compass is 210°, the pitch angle is 45°, and the roll angle is 0°.

[0069] The eighth calibration position, i.e. Figure 3 In the top view position 8 shown, the pitch angle of the seventh calibration position is maintained. After rotating 90° clockwise relative to the seventh calibration position, the sample is taken at rest. At this time, the azimuth angle of the magnetic north pole measuring three-dimensional compass points to 300°, the pitch angle is 45°, and the roll angle is 0°.

[0070] The ninth calibration position, i.e. Figure 3 The top view position 9 shown is rotated 30° clockwise relative to the eighth calibration position, and then the pitch angle is adjusted to -45°±10° for stationary sampling; at this time, the azimuth angle of the magnetic north pole measuring three-dimensional compass points to 60°, the pitch angle is -45°, and the roll angle is 0°.

[0071] The tenth calibration position, i.e. Figure 3 In the top view position 10 shown, the pitch angle of the ninth calibration position is maintained. After rotating 90° clockwise relative to the ninth calibration position, the sample is taken at rest. At this time, the azimuth angle of the magnetic north pole measuring three-dimensional compass is 150°, the pitch angle is -45°, and the roll angle is 0°.

[0072] The eleventh calibration position, namely Figure 3 In the top view position 11 shown, the pitch angle of the tenth calibration position is maintained. After rotating 90° clockwise relative to the tenth calibration position, the sample is taken at rest. At this time, the azimuth angle of the magnetic north pole measuring three-dimensional compass points to 240°, the pitch angle is -45°, and the roll angle is 0°.

[0073] The twelfth calibration position, namely Figure 3 In the top view position 12 shown, the pitch angle of the eleventh calibration position is maintained. After rotating 90° clockwise relative to the eleventh calibration position, the sample is taken at rest. At this time, the azimuth angle of the magnetic north pole measuring three-dimensional compass points to 330°, the pitch angle is -45°, and the roll angle is 0°.

[0074] It should be noted that the azimuth angle mentioned above in this embodiment refers to a relative angle. For example, when placed in the first calibration position (i.e., position 1), the azimuth angle of the magnetic north pole measuring three-dimensional compass can point to any angle, such as 42°. Then, when placed in the second calibration position (i.e., position 2), the azimuth angle of the magnetic north pole measuring three-dimensional compass should differ from this angle by 90°, that is, it should be placed at approximately 132°, with the angle error controlled within 5 to 10°, and so on. The pitch angle and roll angle refer to absolute angles, but when placing them, the angle error of the azimuth angle, pitch angle, and roll angle should be controlled within ±5°.

[0075] Therefore, for ease of operation, the sampling point adjustment process of the twelve calibration positions described in this embodiment is achieved through a tripod turntable and an indexing plate. The magnetic probe circuit board 9 is set on the tripod turntable through the indexing plate. During the rotation of the angle, the angle error is controlled within 5 to 10°.

[0076] In this embodiment, the definitions of azimuth, pitch, and roll are as follows: Figure 4 As shown, the azimuth angle refers to the orientation angle of the X-axis magnetic sensor, that is... Figure 4 The angle along the NOUTH axis has a measurement range of 0° to 360°, with 0° pointing towards magnetic north and clockwise rotation being positive. The pitch angle refers to the orientation angle of the Y-axis magnetic sensor. Figure 4 The angle along the PITCH axis is measured from -90° to 90°, with 0° for horizontal orientation, positive for upward tilting, and negative for downward tilting. The roll angle refers to the Z-axis magnetic sensor orientation angle, i.e. Figure 4 The angle along the HEADING axis is measured from -180° to 180°, with 0° for horizontal orientation, positive for right tilt, and negative for left tilt.

[0077] In short, the installation angles of the acceleration acquisition and calculation circuit board 3 and the magnetic probe circuit board 9 described in this embodiment are defined as follows: the azimuth angle refers to the X-axis direction, with a measurement range of 0° to 360°, 0° when pointing to magnetic north, and clockwise rotation is positive; the pitch angle refers to the Y-axis direction, with a measurement range of -90° to 90°, 0° when horizontal, upward tilt is positive, and downward tilt is negative; the roll angle refers to the Z-axis direction, with a measurement range of -180° to 180°, 0° when horizontal, right tilt is positive, and left tilt is negative.

[0078] In this embodiment, the acceleration acquisition and processing circuit board 3 and the magnetic probe circuit board 9 are installed in a "standard 0°" configuration, and the orientations of the three magnetic sensors are defined as follows: Figure 4As shown, the A-axis accelerometer sensor direction is along the length direction, with vertical downwards being positive; the B-axis accelerometer sensor direction is along the right-hand direction; and the C-axis accelerometer sensor direction is vertically downwards. These three directions form a right-handed coordinate system. The directions of the three corresponding magnetic sensors are the same as the accelerometer sensor directions: the X-axis magnetic sensor direction (north is positive) is the same as the A-axis accelerometer sensor direction; the Y-axis magnetic sensor direction is the same as the B-axis accelerometer sensor direction; and the Z-axis magnetic sensor direction is the same as the C-axis accelerometer sensor direction.

[0079] In this embodiment, step S3 is described by formula. The coefficients of the ellipsoid equation are calculated to determine the ellipsoid center offset (Center), and this ellipsoid center offset (Center) is used as the fixed zero point for the magnetic field interference of the magnetic probe circuit board 9.

[0080] Using the VD decomposition method, the eigenvectors and corresponding eigenvalues ​​of the matrix Mat_r(1:3,1:3) are obtained. The matrix Mat_r(1:3,1:3) represents a 3x3 matrix composed of the first three rows and three columns of the matrix Mat_r. The eigenvector matrix RV and the eigenvalue diagonal matrix RD obtained after VD decomposition satisfy the following equation: RV*RD*RV T =Mat_r(1:3,1:3), where RD represents the diagonal matrix composed of the eigenvalues ​​of the matrix Mat_r(1:3,1:3), and RV represents the matrix composed of the eigenvectors corresponding to the eigenvalues. This can be obtained using the eig function (matrix analysis function) in MATLAB or through a recursive iterative method.

[0081] Specifically, step S4 in this embodiment includes the following sub-steps:

[0082] Step S401, using the formula The eigenvalues ​​Mat_r after decomposition are obtained, where Center(1:3) represents the first to third vector elements in the ellipsoid center offset Center, and 1:3 represents the numbers 1 to 3.

[0083] Step S402, using the formula Calculate the ellipsoidal axis length Radii of the magnetic field model, where RD represents a diagonal matrix composed of eigenvalues ​​Mat_r, and RD(i) represents the eigenvalue elements; i is a natural number from 1 to 3;

[0084] Step S403: Take the minimum value of the ellipsoid axis length Radi using the formula min_Radii = min(Radii);

[0085] Step S404, using the formula The minimum axis length min_Radii is normalized by the scale coefficient to obtain the normalized scale coefficient Scale, where Radii(i) represents the ellipsoid axis length;

[0086] Step S405, using the formula mat_Correct = RV * Scale * RV T Calculate the scale coefficient matrix mat_Correct of the magnetic probe circuit board 9, where RV represents the matrix composed of the eigenvectors corresponding to the eigenvalue Mat_r.

[0087] Finally, after compensation by the calibration coefficient matrix mat_Correct and the ellipsoid center offset Center, the raw magnetometer data can be directly used to calculate the heading. The compensation process is as follows: compensation is performed using the formula Mag = mat_Correct * (Mag' - Center), where Mag' represents the original uncalibrated three-axis magnetometer vector, and Mag represents the calibrated and compensated three-axis magnetometer vector.

[0088] Since this embodiment utilizes the principle of geomagnetism for azimuth measurement, placing the magnetic north pole measuring three-dimensional compass away from iron, magnets, engines, and other magnetic objects, and more specifically, placing the magnetic probe circuit board 9 away from iron, magnets, engines, and other magnetic objects, can effectively reduce magnetic interference from the installation environment. Preferably, in this embodiment, the distance between the installation position of the second mounting reference surface 7 and the magnetic medium object is controlled to be more than 40cm. The magnetic medium object includes any one or more of iron, magnets, and engines. The measurement effect is best at this distance, and as long as the distance between the installation position of the second mounting reference surface 7 and the magnetic medium object is controlled to be more than 40cm, there are no other installation limitations.

[0089] Of course, in practical applications, the installation position of the magnetic probe circuit board 9 and its distance from the magnetic medium object are sometimes uncontrollable. Therefore, when the distance between the installation position of the second mounting reference surface 7 and the magnetic medium object is less than 40cm, after fixing the second mounting reference surface 7 and the magnetic medium object, the magnetic probe circuit board 9 and the magnetic medium object are controlled to rotate synchronously for calibration. This is equivalent to fixing the magnetic medium object and the magnetic probe circuit board 9 relative to each other in advance, maintaining the relative position and distance between the magnetic probe circuit board 9 and the magnetic medium object. This allows the magnetic interference brought by the magnetic medium object to be used as the basic data for overall calibration from the beginning, so as to ensure the effectiveness of calibration and correction, thereby improving the azimuth angle measurement accuracy of the magnetic compass and maximizing the high-precision measurement performance of the three-dimensional compass.

[0090] In summary, this embodiment achieves a split design between the acceleration acquisition and calculation circuit board 3 and the magnetic probe circuit board 9 through the first mounting reference surface 1, the second mounting reference surface 7, and the dual-ended terminal wire 5. It also provides an optimized spatial calibration process for the magnetic probe circuit board 9. This not only makes the magnetic probe circuit board 9 smaller and easier to install in any space with a good magnetic field environment to collect magnetic data, but also allows the acceleration acquisition and calculation circuit board 3 to be installed in any environment, effectively reducing the limitations of the installation environment. Furthermore, the optimized spatial calibration process provides a good foundation for improving the measurement accuracy of the product, facilitating the promotion and application of the product.

[0091] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of this embodiment. It should not be construed that the specific implementation of this embodiment is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of this embodiment, and all such modifications and substitutions should be considered within the protection scope of this embodiment.

Claims

1. A three-dimensional magnetic north pole measuring compass with a split design, characterized in that, include: The system comprises a first mounting reference surface, an acceleration acquisition and processing circuit board, a dual-ended terminal wire, a second mounting reference surface, and a magnetic probe circuit board. The acceleration acquisition and processing circuit board is disposed on the first mounting reference surface, and the magnetic probe circuit board is disposed on the second mounting reference surface. The acceleration acquisition and processing circuit board is connected to the magnetic probe circuit board via the dual-ended terminal wire. The spatial calibration process of the magnetic probe circuit board includes the following steps: Step S1: Construct the ellipsoid equation for the magnetic field model of the magnetic probe circuit board; Step S2: Obtain the coefficient matrix corresponding to the ellipsoid equation based on the sampling point data at the calibration position; Step S3: Calculate the ellipsoid center offset based on the coefficients of the ellipsoid equation, and use the ellipsoid center offset as the fixed zero point of the magnetic field interference of the magnetic probe circuit board. Step S4: Obtain the eigenvalues ​​of the decomposed matrix based on the fixed zero point of the magnetic field interference, and calculate the scale coefficient matrix of the magnetic probe circuit board based on the eigenvalues.

2. The split-type magnetic north pole measuring three-dimensional compass according to claim 1, characterized in that, In step S1, the formula Ax is used. 2 +By 2 +Cz 2 +2Dxy+2Exz+2Fyz+2Gx+2Hy+2Iz=1 An ellipsoidal equation is constructed for the magnetic field model of the magnetic probe circuit board, where A, B, C, D, E, F, G, H and I represent the nine coefficients of the ellipsoidal equation, and x, y and z represent the coordinates of the triaxial magnetometer in the magnetic probe circuit board.

3. The split-type magnetic north pole measuring three-dimensional compass according to claim 2, characterized in that, Step S2 includes the following sub-steps: Step S201, using the formula Hk = [x 2 ,y 2 ,z 2 ,2xy,2xz,2yz,2x,2y,2z] 12×9 Calculate matrix Hk, where Hk represents a 12×9 matrix; Step S202, using the formula Xk=(Hk) T *Hk) T *Hk T *Yk calculates the coefficient matrix Xk, where Xk represents a 9×1 coefficient matrix, corresponding to the nine coefficients A, B, C, D, E, F, G, H, and I; the superscript T indicates the transpose matrix; Yk represents a 12×1 first-order matrix, used to represent the sampling point data at the twelve calibration positions.

4. The split-type magnetic north pole measuring three-dimensional compass according to claim 3, characterized in that, In step S202, the sampling of the twelve calibration positions includes: First calibration position: horizontal placement, stationary sampling in any direction; The second calibration position is placed horizontally, rotated 90° clockwise relative to the first calibration position, and then sampled at rest. The third calibration position is placed horizontally, rotated 90° clockwise relative to the second calibration position, and then sampled at rest. The fourth calibration position is placed horizontally, rotated 90° clockwise relative to the third calibration position, and then sampled at rest. At the fifth calibration position, after rotating 30° clockwise relative to the fourth calibration position, adjust the pitch angle to 45°±10° and perform static sampling. At the sixth calibration position, maintain the pitch angle of the fifth calibration position, rotate 90° clockwise relative to the fifth calibration position, and then sample at rest; At the seventh calibration position, maintain the pitch angle of the sixth calibration position, rotate 90° clockwise relative to the sixth calibration position, and then sample from a stationary position. At the eighth calibration position, maintain the pitch angle of the seventh calibration position, rotate 90° clockwise relative to the seventh calibration position, and then sample at rest; At the ninth calibration position, rotate 30° clockwise relative to the eighth calibration position, then adjust the pitch angle to -45°±10° and perform stationary sampling. At the tenth calibration position, maintain the pitch angle of the ninth calibration position, rotate 90° clockwise relative to the ninth calibration position, and then sample at rest; At the eleventh calibration position, maintain the pitch angle of the tenth calibration position, rotate 90° clockwise relative to the tenth calibration position, and then sample at rest. At the twelfth calibration position, maintain the pitch angle of the eleventh calibration position, rotate 90° clockwise relative to the eleventh calibration position, and then sample at rest.

5. The split-type magnetic north pole measuring three-dimensional compass according to claim 4, characterized in that, The adjustment process of the sampling points at the twelve calibration positions is achieved through a tripod turntable and an indexing plate. The magnetic probe circuit board is set on the tripod turntable through the indexing plate. During the rotation of the angle, the angle error is controlled within 5 to 10°.

6. The split-type magnetic north pole measuring three-dimensional compass according to any one of claims 2 to 5, characterized in that, Step S3 is achieved through the formula The coefficients of the ellipsoid equation are calculated to determine the ellipsoid center offset (Center), and this ellipsoid center offset (Center) is used as the fixed zero point for the magnetic field interference of the magnetic probe circuit board.

7. The split-type magnetic north pole measuring three-dimensional compass according to claim 6, characterized in that, Step S4 includes the following sub-steps: Step S401, using the formula The eigenvalues ​​Mat_r after decomposition are obtained, where Center(1:3) represents the first to third vector elements in the ellipsoid center offset Center, and 1:3 represents the numbers 1 to 3. Step S402, using the formula Calculate the ellipsoidal axis length Radii of the magnetic field model, where RD represents a diagonal matrix composed of eigenvalues ​​Mat_r, and RD(i) represents the eigenvalue elements; i is a natural number from 1 to 3; Step S403: Take the minimum value of the ellipsoid axis length Radi using the formula min_Radii = min(Radii); Step S404, using the formula The minimum axis length min_Radii is normalized by the scale coefficient to obtain the normalized scale coefficient Scale, where Radii(i) represents the ellipsoid axis length; Step S405, using the formula mat_Correct = RV * Scale * RV T Calculate the scale coefficient matrix mat_Correct of the magnetic probe circuit board, where RV represents the matrix composed of the eigenvectors corresponding to the eigenvalues ​​Mat_r.

8. The split-type three-dimensional magnetic north pole measuring compass according to any one of claims 1 to 5, characterized in that, The distance between the installation position of the second mounting reference surface and the magnetic medium object is controlled to be more than 40cm. The magnetic medium object includes any one or more of iron, magnets and engines.

9. The split-type three-dimensional magnetic north pole measuring compass according to any one of claims 1 to 5, characterized in that, When the distance between the second mounting reference surface and the magnetic medium object is less than 40cm, after fixing the second mounting reference surface and the magnetic medium object, control the magnetic probe circuit board and the magnetic medium object to perform synchronous rotation calibration.

10. The split-type three-dimensional magnetic north pole measuring compass according to any one of claims 1 to 5, characterized in that, The installation angles of the acceleration acquisition and processing circuit board and the magnetic probe circuit board are defined as follows: azimuth angle refers to the X-axis direction, with a measurement range of 0° to 360°, 0° when pointing to magnetic north, and positive when rotating clockwise; pitch angle refers to... The Y-axis direction is used for measurement, with a range of -90° to 90°. Horizontal is 0°, with upward tilting being positive and downward tilting being negative. The roll angle refers to the Z-axis direction, and the measurement range is -180° to 180°. It is 0° when horizontal, positive when tilted to the right and negative when tilted to the left.

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