CN101241009A - A kind of magnetic electronic compass error compensation method - Google Patents

Abstract

The invention proposes a magnetic electronic compass error compensation method based on deformation circle distribution and periodic assumption. To improve the measurement accuracy of the magnetic electronic compass, the measurement errors caused by surrounding ferromagnetic materials and other factors must be compensated. At present, the popular compensation methods at home and abroad are based on the assumption that the distribution of the horizontal projection component of the magnetic field intensity changes from a perfect circle to an ellipse due to the influence of the environmental disturbance magnetic field. However, because there are many influencing factors and the situation is complicated, it is actually impossible to ensure that the distribution of the horizontal projection component of the magnetic field intensity is strictly elliptical. In view of this situation, the present invention proposes an error compensation algorithm based on deformation circle distribution and periodicity assumptions to compensate measurement errors caused by surrounding ferromagnetic materials and other factors, and realize high-precision measurement of geomagnetic azimuth.

Description

A kind of magnetic electronic compass error compensation method

technical field

The patent of the invention relates to a magneto-electronic compass that utilizes the geomagnetic field to realize the orientation function, and provides a measurement error compensation method of the magneto-electronic compass.

Background technique

When the magnetic electronic compass is fixed on the carrier, the geomagnetic azimuth measurement results will be affected by the surrounding ferromagnetic materials. The interference magnetic field is composed of two parts: hard iron magnetic field and soft iron magnetic field. When there is an interfering magnetic field around, the distribution of the horizontal projection component of the magnetic field intensity is no longer a perfect circle, its shape is distorted (the influence of the soft iron magnetic field), and its center position is also offset relative to the origin of the coordinates (the influence of the hard iron magnetic field Influence). The existence of the above factors leads to the measurement error of the magnetic electronic compass in the process of measuring the geomagnetic azimuth. The more popular compensation algorithms at home and abroad are based on the assumption that the distribution of the horizontal projection component of the magnetic field intensity changes from a perfect circle to an ellipse due to the influence of the environmental disturbance magnetic field. That is, the distribution of the horizontal projection component of the magnetic field intensity is fitted according to the ellipse, and the relevant coefficient is obtained, and the magnetic field measurement value is compensated according to the relevant coefficient during use. The above compensation algorithm assumes that the distribution of the horizontal projection component of the magnetic field intensity is a regular ellipse, but in fact, due to the complexity of the specific situation, it is difficult to ensure the strict establishment of this condition, thus limiting the improvement of measurement accuracy.

Contents of the invention

The invention proposes an error compensation algorithm based on deformed circle distribution and periodic assumptions to compensate measurement errors caused by factors such as surrounding ferromagnetic materials, and is a method applicable to magnetic and electronic compass error compensation.

The present invention is a method that can be used for error compensation of a magnetic electronic compass. When the magnetic electronic compass rotates multiple times at a constant speed in the surrounding environment, then the azimuth α, the measured uncompensated azimuth α _m , and the azimuth measurement error Δα Both will undergo periodic changes, and can be expressed as a periodic function of the magnetoelectronic compass angle β. In the range of [0, 2π], the function after periodic extension can be expanded into a convergent series form, and the finite term can be used to approximate the function by the algebraic sum of

$\mathrm{<span\; class="notranslate">\; \&Delta;\&alpha;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; n\&alpha;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; n\&alpha;</span>}<span\; class="notranslate">\; )</span>$

Among them, j is a finite positive integer, a0, an, bn, (n=1, 2, 3, ...) are coefficients,

The calibration process consists of the following steps:

(1) Rotate the non-magnetic turntable equipped with magnetic electronic compass and calibration device to make it point to true north, and confirm that the azimuth angle is 0 degrees at this time; (2) Calculate the approximate value of azimuth angle α according to the measured magnetic field data and local magnetic declination data _m ;

(3) Calculate the azimuth angle error Δα=α _m −α according to the rotation angle data α output by the calibration device;

(4) Turn the non-magnetic turntable to increase the azimuth angle by a certain angle, repeat the second and third steps, and obtain the azimuth error of the magnetic electronic compass at the corresponding azimuth angle. Until the azimuth reaches 360 degrees (same as 0 degrees);

(5) Calculate the compensation formula according to the azimuth error

$\mathrm{<span\; class="notranslate">\; \&Delta;\&alpha;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; n\&alpha;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; n\&alpha;</span>}<span\; class="notranslate">\; )</span>$

The compensation coefficients a0, an, bn (n=1, 2, 3, ...) in the.

When in use, the correction value will be calculated according to the coefficient of the compensation formula obtained through calibration, and the steps are as follows:

(1) Calculating the approximate value of the azimuth angle α _m according to the measured magnetic field data and the local magnetic declination data;

(2) According to the compensation formula $\mathrm{\&Delta;\&alpha;}=a_0+\underset{\mathrm{no}=1}{\overset{j}{\mathrm{\&Sigma;}}}(a_{\mathrm{no}}\cos \mathrm{n\&alpha;}+b_{\mathrm{no}}\sin \mathrm{n\&alpha;})$ To calculate the correction value -Δα, first use the azimuth approximate value α _m to replace the azimuth real value α, and perform multiple iterations if higher precision is required;

(3) Calculate the measured value of the azimuth angle after compensation α'=α _m +(-Δα).

Advantages of the present invention"

An error compensation algorithm based on deformation circle distribution and periodic assumption is proposed to compensate the measurement error caused by surrounding ferromagnetic materials and other factors, and realize high-precision measurement of geomagnetic azimuth.

Detailed ways

A specific example of using the patent of the present invention to realize the error compensation of the magnetic electronic compass is given below.

以双轴加速度传感器为俯仰角(θ)和横滚角(γ)测量传感器。综合以上多个传感器的信息，实现地磁方位角的高精度测量。In this example, the high-performance three-axis magnetoresistance sensor is used as the geomagnetic azimuth sensor to measure the components of the geomagnetic field on the x-axis, y-axis, and z-axis of the carrier

A dual-axis acceleration sensor is used as a pitch angle (θ) and roll angle (γ) measurement sensor. Combining the information of the above multiple sensors, the high-precision measurement of the geomagnetic azimuth is realized.

The realization of the magnetic electronic compass error compensation method proposed by the patent of the present invention is divided into two stages, that is, the coefficient calculation stage of the calibration process and the error compensation stage of the use process. In the calibration process, the compensation formula coefficient is calculated according to the measurement error value; in the use process, the compensation formula and related coefficients are used to calculate the correction value to realize error compensation.

When the magnetoelectronic compass rotates multiple times at a constant speed in the surrounding environment, the measured uncompensated azimuth α _m and azimuth measurement error Δα will have periodic changes, which can be expressed as a periodic function of the azimuth α , in the range of [0, 2π], the function after periodic extension is developed into the form of a convergent series, which can be approximated by the algebraic sum of finite terms, namely

$\mathrm{<span\; class="notranslate">\; \&Delta;\&alpha;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; n\&alpha;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; n\&alpha;</span>}<span\; class="notranslate">\; )</span>$

Among them, j is a finite positive integer, a0, an, bn, (n=1, 2, 3, ...) are coefficients,

During calibration, the magnetic electronic compass is installed on a non-magnetic turntable, and the turntable angle is measured by a high-precision photoelectric encoder. The calibration process consists of the following steps.

The first step is to turn the non-magnetic turntable so that it points forward to the north, reset the output of the photoelectric encoder, and confirm that the azimuth is 0 degrees.

In the second step, an approximate value of the azimuth angle is calculated based on the measured data. First, calculate the magnetic field strength horizontal projection H _x , H _y according to the following formula

为磁传感器在θ≠0，γ≠0状态下测得的3个地磁场分量。In the formula,

are the three geomagnetic field components measured by the magnetic sensor in the state of θ≠0 and γ≠0.

Then, calculate the approximate value of geomagnetic azimuth according to H _x , H _y

${\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}}{{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}}<span\; class="notranslate">\; )</span>$

Finally, an approximation of the azimuth is calculated from the local declination value D ,

${\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; D.</span>}$

The third step is to calculate the azimuth error according to the rotation angle data α output by the photoelectric encoder.

Δα＝α _m -α

The fourth step is to rotate the non-magnetic turntable to increase the azimuth angle by 15 degrees, repeat the second and third steps, and obtain the azimuth angle error of the magnetic electronic compass at the corresponding azimuth angle. Until the azimuth reaches 360 degrees (same as 0 degrees).

The fifth step is to calculate the compensation formula according to the azimuth error

$\mathrm{<span\; class="notranslate">\; \&Delta;\&alpha;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; n\&alpha;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; n\&alpha;</span>}<span\; class="notranslate">\; )</span>$

The compensation coefficients a0, an, bn (n=1, 2, 3, ...) in the.

In the above calibration process, we only need to turn the non-magnetic turntable to the corresponding angle.

When in use, the correction value will be calculated according to the coefficient of the compensation formula obtained through calibration, and the steps are as follows.

In the first step, an approximate value of the azimuth angle is calculated based on the measured data. First, calculate the magnetic field strength horizontal projection H _x , H _y according to the following formula

为磁传感器在θ≠0，γ≠0状态下测得的3个地磁场分量。In the formula,

are the three geomagnetic field components measured by the magnetic sensor in the state of θ≠0 and γ≠0.

Then, calculate the approximate value of geomagnetic azimuth according to H _x , H _y

${\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}}{{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}}<span\; class="notranslate">\; )</span>$

Finally, an approximation of the azimuth is calculated from the local declination value D

${\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; D.</span>}$

In the second step, according to the compensation formula $\mathrm{\&Delta;\&alpha;}=a_0+\underset{\mathrm{no}=1}{\overset{j}{\mathrm{\&Sigma;}}}\left(a_{\mathrm{no}}\cos \mathrm{n\&alpha;}{+b}_{\mathrm{no}}\sin \mathrm{n\&alpha;}\right)$ To calculate the correction value -Δα, the approximate value α _m of the azimuth angle is used to replace the real value α of the azimuth angle, and multiple iterations are performed if higher precision is required.

The third step is to calculate the measured value of the azimuth angle after compensation α'=α _m +(-Δα).

Claims (2)

1. A method that can be used for magnetic and electronic compass error compensation is characterized in that when the magnetic and electronic compass rotates multiple turns at a constant speed in the surrounding environment, the uncompensated azimuth α _m and azimuth measurement error Δα of the measurement will all be Periodic changes can be expressed in the form of a periodic function of the azimuth α. In the range of [0, 2π], the function after period extension is developed into a convergent series form, which can be expressed by the algebraic sum of finite terms Approximate this function, that is $\text{<span class="notranslate"> \&Delta;\&alpha;=</span>}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; n\&alpha;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; n\&alpha;</span>}<span\; class="notranslate">\; )</span>$ Among them, j is a finite positive integer, a ₀ , a _n , b _n , (n=1, 2, 3,...) are coefficients, and the calibration process includes the following steps: (1) Rotate the non-magnetic turntable equipped with magnetic electronic compass and calibration device to make it point to true north, and confirm that the azimuth angle is 0 degrees at this time; (2) Calculate the azimuth approximate value α _m according to the measured magnetic field data and the local magnetic declination data; (3) Calculate the azimuth angle error Δα=α _m −α according to the rotation angle data α output by the calibration device; (4) Turn the non-magnetic turntable to increase the azimuth angle by a certain angle, repeat the second and third steps, and obtain the azimuth error of the magnetic electronic compass at the corresponding azimuth angle. Until the azimuth reaches 360 degrees (same as 0 degrees); (5) Calculate the compensation formula according to the azimuth error $\text{<span class="notranslate"> \&Delta;\&alpha;=</span>}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; n\&alpha;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; n\&alpha;</span>}<span\; class="notranslate">\; )</span>$ Compensation coefficients a ₀ , a _n , b _n (n=1, 2, 3, . . . ) in . When in use, the correction value will be calculated according to the coefficient of the compensation formula obtained through calibration, and the steps are as follows: (1) Calculating the approximate value of the azimuth angle α _m according to the measured magnetic field data and the local magnetic declination data; (2) According to the compensation formula $\text{\&Delta;\&alpha;=}{a}_0+\underset{\mathrm{no}=1}{\overset{j}{\mathrm{\&Sigma;}}}(a_{\mathrm{no}}\cos \mathrm{n\&alpha;}+b_{\mathrm{no}}\sin \mathrm{n\&alpha;})$ To calculate the correction value -Δα, first use the azimuth approximate value α _m to replace the azimuth real value α, and perform multiple iterations if higher precision is required; (3) Calculate the measured value of the azimuth angle after compensation α'=α _m +(-Δα). 2. a kind of method that can be used for magnetic electronic compass error compensation according to claim 1 is characterized in that described magnetic electronic compass can be based on fluxgate technology, anisotropic magnetoresistance technology, giant magnetoresistance technology, Measuring elements of magnetic measurement technology such as giant magneto-impedance technology.