CN113008227B - Geomagnetic binary measurement method for measuring attitude based on three-axis accelerometer - Google Patents

Abstract

The invention discloses a geomagnetic binary measurement method based on three-axis accelerometer attitude, which comprises the following steps of: s1, carrying a geomagnetic vector measurement system on a mobile carrier to continuously measure a target measurement area, wherein the geomagnetic vector measurement system comprises a triaxial magnetic sensor and a triaxial accelerometer, measuring a three-component magnetic field value under a carrier coordinate system by the triaxial magnetic sensor, and measuring the projection of the acceleration of the carrier relative to an inertial space under the carrier coordinate system by the triaxial accelerometer; s2, acquiring measurement data of a triaxial accelerometer, and solving a pitching attitude angle and a rolling attitude angle of the carrier under a geographic coordinate system according to the measurement data of the triaxial accelerometer; and S3, acquiring the measurement data of the three-axis magnetic sensor, and solving a geomagnetic horizontal component and a geomagnetic vertical component according to the measurement data of the three-axis magnetic sensor and the solved pitching attitude angle and rolling attitude angle. The invention has the advantages of simple realization and operation, low cost, high measurement precision, strong anti-interference performance, safety, reliability and the like.

Description

A two-component measurement method of geomagnetism based on three-axis accelerometer attitude measurement

technical field

The invention relates to the technical field of magnetic measurement, in particular to a geomagnetic two-component measurement method based on three-axis accelerometer attitude measurement.

Background technique

The geomagnetic field is a vector field. In the geographic coordinate system, its three components are northward component X, eastward component Y, and vertical component Z. The northward component and eastward component can be synthesized into geomagnetic horizontal component H. The geomagnetic vector has rich optional information and significant features, which can effectively improve the accuracy of geomagnetic matching navigation. The three components of the geomagnetic field are used in the geomagnetic vector measurement and navigation, and in order to realize the geomagnetic three-component measurement, the full attitude information of the carrier must be provided. Traditionally, the geomagnetic vector measurement is usually based on the attitude measurement of the inertial navigation system, that is, in the actual measurement, the three Euler angles between it and the geographic coordinate system (pitch angle, Roll angle and yaw angle), so that the output of the three-axis magnetic sensor is converted into a projection in the geographic coordinate system, and the geomagnetic three-component measurement is realized. However, due to the drift accumulation of the inertial navigation system's own inertial device measurement errors, the cumulative error of the provided yaw angle is transferred to the geomagnetic vector measurement value through coordinate rotation, which in turn leads to the problems of low geomagnetic vector measurement accuracy and unreliable measurement results. At the same time, the traditional geomagnetic vector measurement system needs to adopt a high-precision inertial navigation system, which makes the overall volume and mass of the system larger, and also restricts its application in small and medium-sized aerial unmanned platforms.

In order to alleviate the above problems, in the prior art, the measurement error of the geomagnetic vector measurement system is usually corrected after the measurement is completed. The correction method is based on the principle of invariant modulus of the geomagnetic field, deriving the three-axis measurement value of the sensor and the scalar value of the magnetic field The linearized parameter model between them is estimated by least squares to obtain the sensor error parameters, so as to realize the error correction; or use the ellipse fitting method to estimate the sensor error model parameters and error correction, or calculate the geomagnetic field of the test area according to the global geomagnetic model. For the magnetic field vector value, the geomagnetic vector measurement model is established with the output values of the three-axis magnetic sensor and the three-axis inertial element, and the error model parameters and the compensated geomagnetic field value vector are obtained after solving the equations. However, the above correction methods are for single or comprehensive error correction for the output results of the geomagnetic vector measurement system. Due to the error transmission in the system, the measurement accuracy will be reduced. For example, the geomagnetic field vector itself obtained by the global geomagnetic model also has errors, which will also affect The accuracy of parameter estimation reduces the accuracy of error calibration, and it cannot fundamentally solve the accuracy problem caused by the attitude output drift of the inertial navigation system, so it cannot meet the application scenarios such as long-term geomagnetic vector measurement and vector matching navigation.

Some practitioners proposed to compensate the measurement error of the geomagnetic vector measurement system by measuring and correcting the attitude angle of the system. For example, based on the multi-attitude direct calculation method, each component of the three-axis magnetometer output under multiple attitudes is directly used to calculate the error and However, on the one hand, the attitude accuracy after correction in this type of method is still not high enough, on the other hand, the magnetic sensor will destroy the attitude information contained in the output in the presence of magnetic interference.

In summary, the traditional geomagnetic vector measurement method based on inertial navigation system attitude measurement has problems such as inertial navigation output drift and unreliable heading angle caused by the susceptibility of the magnetic sensor itself to interference. However, for the attitude output correction method of the system, the accelerometer cannot Correcting the heading angle is usually solved by using the accelerometer and magnetic sensor for attitude angle fusion correction, but the magnetic sensor is extremely susceptible to external magnetic interference, which will destroy the attitude information contained in the output, thereby reducing the accuracy of attitude estimation.

Contents of the invention

The technical problem to be solved by the present invention is that: aiming at the technical problems existing in the prior art, the present invention provides a three-axis accelerometer-based attitude measurement method that realizes simple operation, low cost, high measurement accuracy, strong anti-interference, and safety and reliability. The geomagnetic two-component measurement method.

In order to solve the problems of the technologies described above, the technical solution proposed by the present invention is:

A geomagnetic two-component measurement method based on three-axis accelerometer attitude measurement, the steps comprising:

S1. The geomagnetic vector measurement system carried by the mobile carrier continuously measures the target measurement area. The geomagnetic vector measurement system includes a three-axis magnetic sensor and a three-axis accelerometer, and the three-component magnetic field in the carrier coordinate system is measured by the three-axis magnetic sensor. Value, the projection of the acceleration of the carrier relative to the inertial space under the carrier coordinate system is measured by the three-axis accelerometer, which is the component of the acceleration of gravity on each axis of the carrier coordinate system;

S2. Obtain the measurement data of the three-axis accelerometer, and solve the pitch attitude angle and roll attitude angle of the carrier in the geographic coordinate system according to the measurement data of the three-axis accelerometer;

S3. Obtain the measurement data of the three-axis magnetic sensor, and calculate the geomagnetic horizontal component and vertical component according to the measurement data of the three-axis magnetic sensor and the pitch attitude angle and roll attitude angle obtained in step S2.

Further, during the measurement process in the step S1, the mobile carrier is controlled to travel within the target measurement area at a constant speed.

Further, the mobile carrier is a non-magnetic trolley, the geomagnetic vector measurement system is packaged in a non-magnetic inline bracket, and the geomagnetic vector measurement is fixed on the non-magnetic trolley through the bracket.

Further, when solving the pitch attitude angle and the roll attitude angle in the step S2, according to the measurement data of the three-axis accelerometer, the first coordinate transformation relational expression for the transformation between the carrier space and the geographic space coordinates is first established, and the The first coordinate transformation relational formula includes a Euler rotation matrix, and the pitch attitude angle and roll attitude angle are finally calculated according to the value of the Euler rotation matrix.

建立载体空间与地理空间之间变换的所述第一坐标变换关系式为：Further, the step of solving the pitch attitude angle and the roll attitude angle in the step S2 includes: the carrier coordinate system (X _b , Y _b , Z _b ) is the center point of the geomagnetic vector measurement system as the coordinate origin, and the The sensitive axis of the three-axis magnetic sensor is a coordinate system composed of coordinate axes, and the geographic coordinate system (X _n , Y _n , Z _n ) is based on the center point of the geomagnetic vector measurement system as the origin of coordinates, and the geographic north direction, geographic The east direction and the vertical downward are the coordinate system formed by the x, y, z axes, and the measurement data of the three-axis accelerometer is

The first coordinate transformation relation formula for establishing the transformation between carrier space and geographic space is:

为欧拉旋转矩阵；where g is the acceleration due to gravity,

is the Euler rotation matrix;

The Euler rotation matrix satisfies:

According to the Euler rotation matrix and the first coordinate transformation relation:

Solve to get:

所述横滚姿态角为The final solution obtains that the pitch attitude angle is

The roll attitude angle is

Further, in the step S3, according to the measurement data of the three-axis magnetic sensor, first establish a second coordinate transformation relation between the carrier coordinate system and the geographic coordinate system, and construct and eliminate The relational expression of the geomagnetic horizontal component and the vertical component under the geographic coordinate system of the course angle information; according to the relational expression of the described geomagnetic horizontal component and the vertical component constructed, use the pitch attitude angle, roll attitude calculated by the step S2 angle, and finally solve the geomagnetic horizontal component and vertical component.

Further, the specific steps of the step S3 include:

The measurement value of the three-axis magnetic sensor in the carrier coordinate system is (B _{m, x} , B _{m, y} , B _{m, z} ), and the vector value in the geographic coordinate system is: (B _{n, x} , B _{n , y} , B _{n, z} ), the establishment of the second coordinate transformation relationship is:

为欧拉旋转矩阵；in

is the Euler rotation matrix;

满足：Euler rotation matrix

satisfy:

Among them, φ, θ, γ are heading attitude angle, pitch attitude angle and roll attitude angle respectively;

以及所述第二坐标变换关系式得到：According to the Euler rotation matrix

And the second coordinate transformation relational expression obtains:

B _n,x =cosφ(cosθB _m,x +sinγsinθB _m,y +cosγsinθB _m,z )-sinφ(cosγB _m,y -sinγB _m,z )

B _n,y =cosφ(cosγB _m,y -sinγB _m,z )+sinφ(cosθB _m,x +sinγsinθB _m,y +cosγsinθB _m,z )

B _n,z ＝-sinθB _m,x +sinγcosθB _m,y +cosγcosθB _m,z

And calculate the sum of the squares of the northward component and the eastward component, and construct the relationship between the geomagnetic horizontal component and the vertical component in the geographic coordinate system that eliminates the heading angle information as follows:

Z=-sinθB _m,x +sinγcosθB _m,y +cosγcosθB _m,z .

Among them, H is the horizontal component of geomagnetism, and Z is the vertical component.

Further, the geomagnetic vector measurement system also includes an optically pumped magnetometer for measuring the total amount of the geomagnetic field.

Further, after the step S3, it also includes comparing the calculated geomagnetic horizontal component and vertical component with the total magnetic field measured by the optical pump magnetometer, and determining the final measurement result according to the comparison result.

Compared with the prior art, the present invention has the advantages of:

1. The present invention continuously measures the target measurement area through a geomagnetic vector measurement system based on a three-axis magnetic sensor and a three-axis accelerometer, first uses the measurement data of the three-axis accelerometer to solve the pitch attitude angle and the roll attitude angle, and then uses The calculated pitch attitude angle and roll attitude angle are calculated based on the measurement data of the three-axis magnetic sensor to obtain the geomagnetic horizontal component and vertical component. During the measurement process, the heading angle information is not required, so that the dependence on the inertial navigation system can be eliminated, ensuring Geomagnetic vector measurement accuracy and reliability.

2. The present invention can eliminate the heading angle parameter in the original geomagnetic vector measurement equation by establishing the attitude angle mathematical model based on the accelerometer output and the geomagnetic vector mathematical model, and then establish the geomagnetic two-component mathematical model by using nonlinear combination operation. The heading angle information necessary for the traditional geomagnetic vector measurement can avoid the drift error caused by the attitude measurement of the inertial system during the measurement process, thereby eliminating the dependence on the inertial navigation system and improving the accuracy and reliability of the geomagnetic vector measurement.

3. The present invention can be applied to small and medium-sized platforms to realize geomagnetic vector measurement with low equipment requirements, no dependence on inertial navigation to provide heading angle information, small volume, simple operation and small calculation amount, and solve the problem of inertial navigation output drift and The magnetic sensor itself is susceptible to problems such as unreliable heading angle caused by interference.

Description of drawings

FIG. 1 is a schematic diagram of the implementation flow of the geomagnetic two-component measurement method based on three-axis accelerometer attitude measurement in this embodiment.

Fig. 2 is a schematic diagram of the structure and principle of this embodiment to realize two-component measurement of geomagnetism.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

As shown in Figure 1, the steps of the geomagnetic two-component measurement method based on the three-axis accelerometer attitude measurement in this embodiment include:

S1. The geomagnetic vector measurement system carried by the mobile carrier continuously measures the target measurement area. The geomagnetic vector measurement system includes a three-axis magnetic sensor and a three-axis accelerometer. The three-axis magnetic sensor measures the three-component magnetic field value in the carrier coordinate system. The axial accelerometer measures the projection of the acceleration of the carrier relative to the inertial space in the carrier coordinate system, which is the component of the acceleration of gravity on each axis of the carrier coordinate system;

S2. Obtain the measurement data of the triaxial accelerometer, and solve the pitch attitude angle and roll attitude angle of the carrier in the geographic coordinate system according to the measurement data of the triaxial accelerometer;

S3. Obtain the measurement data of the three-axis magnetic sensor, and calculate the geomagnetic horizontal component and vertical component according to the measurement data of the three-axis magnetic sensor and the pitch attitude angle and roll attitude angle obtained in step S2.

In this embodiment, the target measurement area is continuously measured through a geomagnetic vector measurement system based on a three-axis magnetic sensor and a three-axis accelerometer. The obtained pitch attitude angle and roll attitude angle are calculated based on the measurement data of the three-axis magnetic sensor to obtain the geomagnetic horizontal component and vertical component. During the measurement process, the heading angle information is not required, so that the dependence on the inertial navigation system can be eliminated, and then Avoid the drift error caused by the attitude measurement of the inertial system during the measurement process, and improve the accuracy and reliability of the geomagnetic vector measurement.

In this embodiment, the mobile carrier is specifically a non-magnetic trolley. As shown in Figure 2, a strap-down geomagnetic vector measurement system without inertial navigation is composed of a three-axis accelerometer and a three-axis magnetic sensor. The geomagnetic vector measurement system is packaged in a non-magnetic "one Font” bracket, fix the bracket on the non-magnetic trolley, control the non-magnetic trolley to drive in the target measurement area at a constant speed during the measurement process to obtain measurement data, establish a geographic coordinate system, and the two components of the geomagnetic field in the geographic coordinate system are respectively The horizontal component H and the vertical component Z are used to project the gravitational acceleration g on the sensitive axis of the three-axis accelerometer in the state of uniform motion to calculate the two attitude angles of the carrier pitch and roll, and then provide the necessary attitude parameters for the subsequent geomagnetic two-component measurement.

In this embodiment, the geomagnetic field in the calibration area in the above step S1 is stable, and the non-magnetic trolley needs to keep moving at a constant speed; in the strapdown measurement system, the magnetic field sensor and the sensitive axis of the accelerometer need to be precisely aligned and calibrated in advance.

When solving the pitch attitude angle and the roll attitude angle in step S2 of this embodiment, according to the measurement data of the three-axis accelerometer, first establish the first coordinate transformation relationship between the carrier space and the geographical space coordinates, the first coordinate transformation relationship The formula includes the Euler rotation matrix, and finally calculates the pitch attitude angle and roll attitude angle according to the value of the Euler rotation matrix.

In this embodiment, the carrier coordinate system (X _b , Y _b , Z _b ) is a coordinate system with the center point of the geomagnetic vector measurement system as the coordinate origin and the sensitive axis of the three-axis magnetic sensor as the coordinate axis. The geographic coordinate system (X _n , Y _n , Z _n ) is a coordinate system composed of the center point of the geomagnetic vector measurement system as the coordinate origin, and the geographic north, geographic east, and vertical downward as x, y, and z axes, respectively. The three-axis accelerometer is only affected by gravity in the state of uniform motion, so the data measured by the three-axis acceleration is the projection of the acceleration of the carrier relative to the inertial space in the carrier coordinate system (X _b , Y _b , Z _b ), which is also That is, the components of the gravitational acceleration g on each axis of the carrier coordinate system.

The detailed steps for solving pitch attitude angle and roll attitude angle in step S2 of the present embodiment include:

建立载体空间与地理空间之间变换的第一坐标变换关系式为：(a) The measured data of the three-axis accelerometer is

The first coordinate transformation relation formula for establishing the transformation between carrier space and geographic space is:

为欧拉旋转矩阵；where g is the acceleration due to gravity,

is the Euler rotation matrix;

(b) The Euler rotation matrix satisfies:

According to the Euler rotation matrix and the first coordinate transformation relation:

Then it is solved to get:

横滚姿态角为

The final solution obtains the pitch attitude angle as

The roll attitude angle is

In step S3 of this embodiment, specifically based on the measurement data of the three axes, the second coordinate transformation relational expression between the carrier coordinate system and the geographic coordinate system is first established, and the geographic coordinate system for eliminating the course angle information is constructed according to the second coordinate transformation relational expression The relationship between the geomagnetic horizontal component and the vertical component; according to the constructed relationship between the geomagnetic horizontal component and the vertical component, use the pitch attitude angle and roll attitude angle calculated in step S2 to finally solve the geomagnetic horizontal component and vertical portion.

The specific steps of step S3 in this embodiment include:

The measurement value of the three-axis magnetic sensor in the carrier coordinate system is (B _m,x ,B _m,y ,B _m,z ), and the vector value in the geographic coordinate system is: (B _n,x ,B _n,y ,B _n,z ), establish the second coordinate transformation relation as:

为欧拉旋转矩阵；in

is the Euler rotation matrix;

满足：Euler rotation matrix

satisfy:

Among them, φ, θ, γ are heading attitude angle, pitch attitude angle and roll attitude angle respectively;

以及第二坐标变换关系式得到：According to the Euler rotation matrix

And the second coordinate transformation relationship is obtained:

B _n,x =cosφ(cosθB _m,x +sinγsinθB _m,y +cosγsinθB _m,z )-sinφ(cosγB _m,y -sinγB _m,z )

B _n,y =cosφ(cosγB _m,y -sinγB _m,z )+sinφ(cosθB _m,x +sinγsinθB _m,y +cosγsinθB _m,z )

B _n,z ＝-sinθB _m,x +sinγcosθB _m,y +cosγcosθB _m,z (8)

And calculate the sum of the squares of the northward component and the eastward component, and construct the relationship between the geomagnetic horizontal component and the vertical component in the geographic coordinate system that eliminates the heading angle information as follows:

Z＝-sinθB _m,x +sinγcosθB _m,y +cosγcosθB _m,z (9)

Among them, H is the geomagnetic horizontal component, and Z is the vertical component.

In this embodiment, the output of the accelerometer is first used to solve the two attitude values of the pitch angle and the roll angle, and then a coordinate conversion simultaneous equation system is established to solve the geomagnetic horizontal component and vertical component expressions under the geographic coordinate system that eliminates the heading angle information. Substituting the pitch and roll attitude angles obtained by the three-axis accelerometer into the known geomagnetic horizontal and vertical component equations, the geomagnetic horizontal component H and vertical component Z can be obtained. By solving the sum of the squares of the geomagnetic north and east vector values, The geomagnetic horizontal component H can eliminate all the heading angle parameters in the simultaneous equations, so as to realize the geomagnetic two-component measurement that does not depend on the heading angle information.

The geomagnetic vector measurement system of this embodiment also includes an optical pump magnetometer for measuring the total amount of the geomagnetic field, that is, the optical pump magnetometer is simultaneously mounted on the nonmagnetic car in step S1 to measure the total geomagnetic field at the position of the nonmagnetic car , denoted as: T _e . After step S3, it also includes comparing the calculated geomagnetic horizontal component and vertical component with the total magnetic field measured by the optical pump magnetometer, and determining the final measurement result according to the comparison result. Specifically, it can be compared whether the calculated geomagnetic horizontal component and vertical component are consistent with the total magnetic field measured by the optical pump magnetometer, so as to realize the mutual verification of the geomagnetic two-component solution and the optical pump magnetometer measurement.

The present invention establishes the attitude angle mathematical model based on the output of the accelerometer and the geomagnetic vector mathematical model, and then uses nonlinear combination operations to eliminate the heading angle parameters in the original geomagnetic vector measurement equation, and establishes a geomagnetic two-component mathematical model, which can eliminate the traditional geomagnetic The necessary heading angle information for vector measurement can avoid the drift error caused by the attitude measurement of the inertial system during the measurement process, improve the accuracy and reliability of the geomagnetic vector measurement, eliminate the dependence on the inertial navigation system, and solve the inertial system in the traditional geomagnetic vector measurement. The problem of unreliable heading angle caused by the output drift and the susceptibility of the magnetic sensor itself to interference, so as to realize the geomagnetic vector measurement with low equipment requirements, not relying on inertial navigation to provide heading angle information, small size, easy operation, and small amount of calculation.

Hereinafter, the present invention will be further described by taking the implementation of the two-component measurement of geomagnetism by applying the above-mentioned method in a specific application embodiment as an example.

In this embodiment, the detailed process for realizing the geomagnetic two-component measurement is as follows:

Step 1: Select a measurement area where the geomagnetic field is stable and relatively uniform (magnetic field gradient <5nT/m), and place a non-magnetic trolley in the measurement area.

Step 2: Install the optical pump magnetometer on the non-magnetic trolley to measure the total geomagnetic field, denoted as T _e ;

Step 3: Install the three-axis magnetic field sensor and the three-axis accelerometer element strapdown that constitute the geomagnetic field vector measurement system on a non-magnetic "one"-shaped bracket, and accurately align and align the sensitive axes of the magnetic field sensor and the accelerometer calibration;

Step 4: Establish coordinate system 1: The coordinate system composed of the center point of the measurement system as the coordinate origin and the sensitive axis of the sensor as the coordinate axis is the carrier coordinate system (X _b , Y _b , Z _b ); establish coordinate system 2: Taking the center point of the measurement system as the origin of the coordinates, and taking the geographic north, geographic east, and vertical downward as x, y, and z axes respectively, the coordinate system is the geographic coordinate system (X _n , Y _n , Z _n ); The attitude angle of the non-magnetic car carrier in the geographic coordinate system is the pitch angle θ and the roll angle γ, and the to-be-measured is the two-component projection B _n = [HZ] of the geomagnetic field vector in the geographic coordinate system;

如式3所示，即为：Step 5: Solve the attitude angle: Determine the Euler angle between the carrier coordinate system and the geographic coordinate system according to the measurement data of the three-axis accelerometer. The heading angle, pitch angle, and roll angle are φ, θ, and γ respectively, and determine the two coordinates Euler rotation matrix between systems

As shown in formula 3, it is:

Step 6: According to the measurement data of the three-axis accelerometer, the coordinate transformation matrix is established according to formula (1), which is:

代入解算后最终解算得到俯仰姿态角

横滚姿态the Euler rotation matrix

After substituting into the solution, the final solution obtains the pitch attitude angle

roll attitude

horn

欧拉旋转矩阵如式(7)Step 7: Solve the geomagnetic two-component, according to the measured value B _m = [B _m,x ,B _m,y ,B _m,z ] of the three-axis magnetic sensor in the carrier coordinate system, and the vector value in the geographic coordinate system (Geomagnetic northward component, eastward component and vertical component) to construct a relational expression for B _n =[B _n,x ,B _n,y ,B _n,z ], which is:

The Euler rotation matrix is as formula (7)

As shown, it can also be expressed as:

Step 8: Construct the coordinate conversion relationship between the three geomagnetic components in the geographic coordinate system and the geomagnetic measurement values in the carrier coordinate system:

B _n,x =cosθcosφB _m,x +(sinγsinθcosφ-cosγsinφ)B _m,y +(sinγsinφ+cosγsinθcosφ)B _m,z

B _n,y =cosθsinφB _m,x +(cosγcosφ+sinγsinθsinφ)B _m,y +(cosγsinθsinφ-sinγcosφ)B _m,z

B _n,z ＝-sinθB _m,x +sinγcosθB _m,y +cosγcosθB _m,z

Further transform to obtain the expression of the geomagnetic vector:

B _n,x =cosφ(cosθB _m,x +sinγsinθB _m,y +cosγsinθB _m,z )-sinφ(cosγB _m,y -sinγB _m,z )

B _n,y ＝cosφ(cosγB _m,y -sinγB _m,z )+sinφ(cosθB _m,x +sinγsinθB _m,y +cosγsinθB _m,z )

B _n,z ＝-sinθB _m,x +sinγcosθB _m,y +cosγcosθB _m,z are further merged and sorted out geomagnetic north component and east component to get:

(B _n,x ) ² +(B _n,y ) ² ＝(cosθB _m,x +sinγsinθB _m,y +cosγsinθB _m,z ) ² +(cosγB _m,y -sinγB _m,z ) ² Solve to get the geomagnetic level Component H:

And combined with the above expression of the vertical component of geomagnetism, the vertical component Z of geomagnetism is obtained:

Z＝-sinθB _m,x +sinγcosθB _m,y +cosγcosθB _m,z

The method described above in this embodiment can realize two-component measurement of geomagnetism based on accelerometer attitude measurement, and obtain two-component values H and Z of geomagnetism that do not depend on heading angle information.

In order to verify the effectiveness of the above-mentioned method of the present invention, adopt the method of the present invention to carry out emulation test in concrete application embodiment, emulation condition is: test area geomagnetic field vector is _Be =[33646-2127 32280] nT (under geographical coordinate system ), the corresponding total geomagnetism is T _e =46675.22nT. The test procedure is as follows:

①Place the non-magnetic car in a stable magnetic field environment, and start recording the output values of the three-axis magnetic field sensor and the three-axis accelerometer;

② Pull the non-magnetic trolley forward at a constant speed on the potholed road with a slope of up to 4°, and start recording the output of the three-axis magnetic field sensor and the three-axis accelerometer;

③Continuously rotate ±90° around the vertical axis of the horizontal plane of the non-magnetic trolley, continue the previous step, and the measured data obtained are shown in Table 1.

Table 1 Measurement data of triaxial accelerometer and magnetic field sensor

其中H是地磁二分量中的水平分量估计，Z是垂向分量估计。Establish equation (9) and use the pitch, roll angle and geomagnetic three-component to solve the geomagnetic two-component as follows:

where H is the estimate of the horizontal component in the two geomagnetic components, and Z is the estimate of the vertical component.

This embodiment first evaluates the required error model parameters and the geomagnetic vector:

是，结合设定的地磁矢量可得，理想条件下，采用本发明根据俯仰横滚角与地磁测量值反演的地磁二分量值(水平分量与垂向分量)与预设值一致。The geomagnetic horizontal component and vertical component obtained according to the simulation parameters are

Yes, combined with the set geomagnetic vector, under ideal conditions, the geomagnetic two-component value (horizontal component and vertical component) inverted by the present invention based on the pitch and roll angle and the geomagnetic measurement value is consistent with the preset value.

This embodiment further simulates the situation where the sensor has measurement noise to evaluate the geomagnetic two-component measurement results:

The measurement noise of the magnetic field sensor is set to Gaussian white noise with a standard deviation of 5nT, and the measurement noise of the triaxial accelerometer is Gaussian white noise with a standard deviation of 0.01 degrees.

In the simulation, the strapdown geomagnetic vector measurement system is mounted on a non-magnetic trolley, and in an uneven area with a stable geomagnetic environment, it is pulled in one direction at a uniform speed for a period of time, and a set of measured values is obtained, as shown in Table 2. Then use formula (9) to solve the two geomagnetic components according to the data in Table 2. Table 3 shows the error between the solution value of the two geomagnetic components and the true value of the geomagnetic field. The error of the horizontal component is less than XnT, and the error of the vertical component is less than XnT.

Table 2 Measurement data of triaxial accelerometer and magnetic field sensor

Table 3 Geomagnetic field two component and total measurement error (nT)

horizontal component vertical component Total -1.27 0.88 -0.31 -2.50 1.29 -0.92 -3.60 0.64 -2.16 -6.03 0.25 -4.18 -6.75 -0.19 -5 -1.03 0.41 -0.46 4.95 1.76 4.8 6.87 2.48 6.68 2.58 2.21 3.39 -4.45 2.28 -1.64 -6.83 2.59 -3.14 -2.84 2.34 -0.43 2.69 -0.42 1.65 6.70 -0.06 4.8 5.76 2.18 5.67 -1.91 2.76 0.53 -5.61 2.06 -2.62 -5.56 2.03 -2.61 -4.94 1.82 -2.31 -2.96 2.72 -0.25 3.98 2.88 4.87 7.19 -0.43 4.9 3.47 0.49 2.85 -3.06 1.22 -1.37 -7.20 1.24 -4.35

It can be seen from the test results that the geomagnetic two-component measurement method based on the three-axis accelerometer attitude measurement of the present invention can eliminate the dependence on the inertial navigation system and effectively improve the accuracy and reliability of the geomagnetic vector measurement.

The above are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims (9)

1. a geomagnetic two-component measurement method based on triaxial accelerometer attitude measurement, is characterized in that, step comprises: S1. The geomagnetic vector measurement system carried by the mobile carrier continuously measures the target measurement area. The geomagnetic vector measurement system includes a three-axis magnetic sensor and a three-axis accelerometer, and the three-component magnetic field in the carrier coordinate system is measured by the three-axis magnetic sensor. Value, the projection of the acceleration of the carrier relative to the inertial space under the carrier coordinate system is measured by the three-axis accelerometer, which is the component of the acceleration of gravity on each axis of the carrier coordinate system; S2. Obtain the measurement data of the three-axis accelerometer, and solve the pitch attitude angle and roll attitude angle of the carrier in the geographic coordinate system according to the measurement data of the three-axis accelerometer; S3. Obtain the measurement data of the three-axis magnetic sensor, and solve the geomagnetic horizontal component and vertical component according to the measurement data of the three-axis magnetic sensor and the pitch attitude angle and roll attitude angle obtained in step S2; In the step S3, the measured value of the three-axis magnetic sensor in the carrier coordinate system is (B _{m, x} , B _{m, y} , B _{m, z} ). The relationship between the component and the vertical component is:

Z＝-sinθB _m,x +sinγcosθB _m,y +cosγcosθB _m,z Wherein H is the geomagnetic horizontal component, Z is the vertical component, θ, γ are the pitch attitude angle and the roll attitude angle respectively; According to the constructed relationship between the geomagnetic horizontal component and the vertical component, the pitch attitude angle and the roll attitude angle calculated in the step S2 are used to finally solve the geomagnetic horizontal component and the vertical component. 2. The geomagnetic two-component measurement method based on three-axis accelerometer attitude measurement according to claim 1, characterized in that, during the measurement process in the step S1, the mobile carrier is controlled to travel in the target measurement area at a constant speed. 3. The geomagnetic two-component measurement method based on three-axis accelerometer attitude measurement according to claim 1, characterized in that: the mobile carrier is a non-magnetic trolley, and the geomagnetic vector measurement system is encapsulated in a non-magnetic In the type bracket, the geomagnetic vector measurement is fixed on the non-magnetic trolley through the bracket. 4. the geomagnetic two-component measurement method based on triaxial accelerometer posture measurement according to claim 1, is characterized in that, when solving pitch attitude angle, roll attitude angle in the described step S2, according to described triaxial accelerometer First establish the first coordinate transformation relational expression of the transformation between the carrier space and the geographic space coordinates of the measurement data, the first coordinate transformation relational expression includes the Euler rotation matrix, and finally solve the value of the Euler rotation matrix according to the value of the Euler rotation matrix Describe the pitch attitude angle and roll attitude angle. 5. the geomagnetic two-component measuring method based on three-axis accelerometer attitude measurement according to claim 4, is characterized in that, the step of solving pitch attitude angle, roll attitude angle in described step S2 comprises: carrier coordinate system (X _b , Y _b , Z _b ) is a coordinate system with the center point of the geomagnetic vector measurement system as the coordinate origin and the sensitive axis of the three-axis magnetic sensor as the coordinate axis. The geographic coordinate system (X _n , Y _n , Z _n ) is a coordinate system that takes the central point of the geomagnetic vector measurement system as the origin of coordinates, and takes geographic north, geographic east, and vertical downward as x, y, and z axes respectively, and the measurement of the three-axis accelerometer The data is

The first coordinate transformation relation formula for establishing the transformation between carrier space and geographic space is:

where g is the acceleration due to gravity,

is the Euler rotation matrix; The Euler rotation matrix satisfies:

Among them, φ, θ, γ are heading attitude angle, pitch attitude angle and roll attitude angle respectively; According to the Euler rotation matrix and the first coordinate transformation relation:

Solve to get:

The final solution obtains that the pitch attitude angle is

The roll attitude angle is

6. The geomagnetic two-component measurement method based on three-axis accelerometer attitude measurement according to any one of claims 1 to 5, characterized in that, in the step S3, according to the measurement data of the three-axis magnetic sensor, First establish the second coordinate transformation relationship between the carrier coordinate system and the geographic coordinate system, according to the second coordinate transformation relationship, construct the relationship between the geomagnetic horizontal component and the vertical component under the geographic coordinate system that eliminates the course angle information; The constructed relational expression of the geomagnetic horizontal component and vertical component uses the pitch attitude angle and roll attitude angle calculated in step S2 to finally solve the geomagnetic horizontal component and vertical component. 7. the geomagnetic two-component measurement method based on triaxial accelerometer attitude measurement according to claim 6, is characterized in that, the specific steps of described step S3 comprise: The measurement value of the three-axis magnetic sensor in the carrier coordinate system is (B _{m, x} , B _{m, y} , B _{m, z} ), and the vector value in the geographic coordinate system is: (B _{n, x} , B _{n , y} , B _{n, z} ), the establishment of the second coordinate transformation relationship is:

in

is the Euler rotation matrix; Euler rotation matrix

satisfy:

Among them, φ, θ, γ are heading attitude angle, pitch attitude angle and roll attitude angle respectively; According to the Euler rotation matrix

And the second coordinate transformation relational expression obtains: B _n,x =cosφ(cosθB _m,x +sinγsinθB _m,y +cosγsinθB _m,z )-sinφ(cosγB _m,y -sinγB _m,z ) B _n,y =cosφ(cosγB _m,y -sinγB _m,z )+sinφ(cosθB _m,x +sinγsinθB _m,y +cosγsinθB _m,z ) B _n,z ＝-sinθB _m,x +sinγcosθB _m,y +cosγcosθB _m,z And calculate the sum of the squares of the northward component and the eastward component, and construct the relationship between the geomagnetic horizontal component and the vertical component in the geographic coordinate system that eliminates the heading angle information as follows:

Z=-sinθB _{m, x} + sinγcosθB _{m, y} + cosγcosθB _{m, z} ; Among them, H is the horizontal component of geomagnetism, and Z is the vertical component. 8. The geomagnetic two-component measurement method based on three-axis accelerometer attitude measurement according to any one of claims 1 to 5, characterized in that, the geomagnetic vector measurement system also includes a method for measuring the total amount of the geomagnetic field Optically pumped magnetometer. 9. The geomagnetic two-component measurement method based on triaxial accelerometer attitude measurement according to claim 8, characterized in that, after the step S3, it also includes combining the solved geomagnetic horizontal component and vertical component with the optical pump The total magnetic field measured by the magnetometer is compared, and the final measurement result is determined according to the comparison result.

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