CN114894219B - A method for double-position calibration of zero bias error of inertial system in the field - Google Patents
A method for double-position calibration of zero bias error of inertial system in the field Download PDFInfo
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- CN114894219B CN114894219B CN202210466057.5A CN202210466057A CN114894219B CN 114894219 B CN114894219 B CN 114894219B CN 202210466057 A CN202210466057 A CN 202210466057A CN 114894219 B CN114894219 B CN 114894219B
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- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
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Abstract
本发明涉及一种惯性系统零偏误差外场双位置校准方法，将IMU绕方位轴作近似180°旋转，通过陀螺输出跟踪转位变化，将跟踪姿态矩阵和第二位置对准姿态矩阵作差求解平台失准角，从而获得陀螺和加速度计零偏的解析解。该方法不依赖于转位精度和北向基准，不受初始航向角的影响，能够对陀螺和加速度计零偏同时进行标定，提高双位置标校方法的准确性、可靠性和外场环境适应性。与背景技术对比，本发明技术不受初始航向角的影响，避免了奇异值的出现，将陀螺漂移标定精度提高至0.01°/h，且能够同时对加速度计零偏进行标定。
The present invention relates to an outdoor dual-position calibration method for zero bias error of an inertial system, wherein an IMU is rotated approximately 180° around an azimuth axis, and the index change is tracked through a gyro output, and the tracking attitude matrix and the second position alignment attitude matrix are used to perform a difference to solve the platform misalignment angle, thereby obtaining an analytical solution for the zero bias of a gyro and an accelerometer. The method does not rely on the index accuracy and the north reference, is not affected by the initial heading angle, can calibrate the zero bias of a gyro and an accelerometer simultaneously, and improves the accuracy, reliability and adaptability of the dual-position calibration method to outdoor environments. Compared with the background technology, the technology of the present invention is not affected by the initial heading angle, avoids the appearance of singular values, improves the calibration accuracy of the gyro drift to 0.01°/h, and can calibrate the zero bias of an accelerometer simultaneously.
Description
Technical Field
The invention belongs to the technical field of inertial navigation, relates to an inertial system zero offset error external field two-position calibration method, and in particular relates to an inertial navigation system zero offset error calibration method under external field conditions.
Background
The inertia device has timeliness, and along with the extension of the service time, the zero bias parameters of the gyroscope and the accelerometer can be changed under the influence of internal stress release, external environment and other factors. In order to ensure the long-term navigation precision, the inertial navigation system usually needs to return to a manufacturer after being used for a certain time, and error calibration is performed again in a laboratory by using equipment such as a high-precision turntable and the like. If the zero offset error is quickly calibrated by a method independent of the indexing precision and the north-orientation reference under the external field condition, the calibration time can be shortened, the transportation cost can be reduced, and the rapidity and the maneuverability of maintenance guarantee can be improved. The method is influenced by observability, and the method for calibrating the external field double positions based on the Kalman filter is difficult to estimate the zero offset of the sky-oriented gyroscope in a short time.
The literature "inertial instrument test and data analysis, national defense industry press 2012, first edition, p220-221" discloses a two-position float measuring method independent of a high-precision turntable. According to the method, a double position is formed by rotating the IMU around an approximately 180-degree direction axis, and an equation set is established according to angular rate output under the two positions to solve the direction misalignment angle, so that the accurate calibration of the triaxial gyro drift is realized. The method can be applied to zero offset calibration of the gyroscope under the external field condition, but the zero offset error of the accelerometer is not calibrated, and when the initial course angle is around 90 degrees and 270 degrees, singular values can appear in the azimuth misalignment angle calculation, so that the accuracy of calibrating the gyroscope drift is reduced.
Disclosure of Invention
Technical problem to be solved
In order to avoid the defects of the prior art, the invention provides a zero offset error external field two-position calibration method of an inertial system, which improves the external field environment adaptability and the calibration precision of the two-position drift measurement method.
Technical proposal
The zero offset error external field two-position calibration method of the inertial system is characterized by comprising the following steps of:
step 1, initially aligning a first position, namely horizontally placing an inertial navigation system, recording the inertial navigation system as the first position, standing for more than 600 seconds in the first position, and recording the average value of the output angular rate of the triaxial gyroscope in the time period And accelerometer output specific force mean valueAnd calculating an initial alignment pose matrix for the first positionThe attitude matrix contains misalignment angle errors
Wherein, N1＝U1×E1;
Step 2, attitude tracking, namely rotating an inertial navigation system around an azimuth axis by 180 degrees to reach a second position, solving an attitude differential equation by using gyro output data in the rotating process, and carrying out an attitude matrix at the moment of finishing rotationIs recorded as
Wherein: For the gesture matrix calculated in the rotation process, the initial value is Outputting an angular rate for the gyroscope; projection of the rotation angular velocity of the earth on an inertial navigation coordinate system;
Step 3, aligning the second position, namely keeping the second position stationary for more than 600 seconds, and recording the average value of the output angular rate of the triaxial gyroscope in the stationary time period And accelerometer output specific force mean valueAccording toAndCalculating an initial alignment pose matrix for the second positionBecause the index is 180 °, the attitude matrix contains misalignment angle errors
Wherein, N2＝U2×E2;
Step4, calculating a misalignment angle according to the gesture tracking matrixAnd a second position alignment pose matrixCalculating the misalignment angle
Calculating a corrected posture matrix
Step 5, zero offset calculation is carried out on the gyroscope and the accelerometer, and the calculation result is injected into the memory parameter of the inertial navigation system to finish zero offset error calibration:
calculating zero offset epsilon b of the gyroscope:
Calculating accelerometer zero offset
Wherein: And g n＝[0 0 -g]T is the projection of the rotation angular rate of the earth on a northeast geographic coordinate system, and g is a local gravitational acceleration module value.
Advantageous effects
According to the inertial system zero offset error external field two-position calibration method, the IMU rotates approximately 180 degrees around the azimuth axis, tracking displacement change is output through the gyroscope, the tracking gesture matrix and the second position alignment gesture matrix are subjected to difference solution to solve the platform misalignment angle, and therefore the analytic solutions of the gyroscope and the accelerometer zero offset are obtained. The method does not depend on indexing accuracy and north reference, is not influenced by an initial course angle, can calibrate zero offset of the gyroscope and the accelerometer at the same time, and improves accuracy, reliability and outfield environment adaptability of the double-position calibration method.
Drawings
FIG. 1 is a diagram of an embodiment of the present invention;
FIG. 2 is a graph of the constant drift calibration error of a gyroscope at an initial heading angle of 90℃for the background art;
FIG. 3 is a plot of gyro constant drift calibration error for the method of the present invention at an initial heading angle of 90;
FIG. 4 is an accelerometer zero offset calibration error for the method of the present invention at an initial heading angle of 90.
Detailed Description
The invention will now be further described with reference to examples, figures:
1. The first position is initially aligned.
Referring to FIG. 1, the inertial navigation system is placed nearly horizontally, the [0, t 1 ] time period is recorded as a first position, the inertial navigation system is static for 600 seconds at the first position, and the output angular rate average value of the tri-axial gyroscope in the time period is recordedAnd accelerometer output specific force mean valueAnd calculating an initial alignment pose matrix for the first positionThe attitude matrix contains misalignment angle errors
Wherein, N1＝U1×E1。
2. And (5) gesture tracking.
The IMU rotates by approximately 180 degrees around the azimuth axis to reach a second position, the rotation process uses gyro output data to update the gesture, and the gesture tracking matrix at the end of rotation is recorded as
Referring to FIG. 1, during the [ t 1,t2 ] period, the IMU is rotated approximately 180 degrees about the azimuth axis to a second position, the gyroscope output data is used to solve the differential equation of the attitude during rotation, and the attitude matrix at the end of rotation is obtainedIs recorded as
Wherein: For the gesture matrix calculated in the rotation process, the initial value is Outputting an angular rate for the gyroscope; Is the projection of the rotation angular velocity of the earth on an inertial navigation coordinate system.
3. The second position is aligned.
Referring to FIG. 1, during a [ t 2,t3 ] period, the tri-axis gyroscope output angular rate average is recorded while remaining stationary at the second position for 600sAnd accelerometer output specific force mean valueAccording toAndCalculating an initial alignment pose matrix for the second positionSince the index is approximately 180 °, the pose matrix contains misalignment angle errors
Wherein, N2＝U2×E2。
4. And calculating a misalignment angle.
Tracking matrix according to gestureAnd a second position alignment pose matrixCalculating the misalignment angle
Calculating a corrected posture matrix
5. And (5) calculating zero offset of the gyroscope and the accelerometer.
Calculating constant drift epsilon b of the gyroscope by the formula (7), and calculating zero offset of the accelerometer by the formula (8)And injecting the calculation result into the memory parameter of the inertial navigation system to finish zero offset error calibration.
Wherein the method comprises the steps ofAnd g n＝[0 0 -g]T is the projection of the rotation angular rate of the earth on a northeast geographic coordinate system, and g is a local gravitational acceleration module value.
The following describes the specific embodiments and implementation effects of the present invention through simulation tests.
The simulation conditions were set as follows, the initial position longitude and latitude height was [110 °;34 °;400m ], the initial pitch, roll and heading angle was [ -2 °;1 °;90 ° ], the attitude of the rotated second position was [0 °;1 °;271 ° ], the gyro zero mean square error was 0.05 °/h, the random walk noise was 0.002 °/-h, the accelerometer zero mean square error was 0.1mg, the random noise was 0.01 mg/-v Hz, and 100 simulation tests were performed in total.
Fig. 2 shows a gyro drift estimation error obtained in the background art. In most cases, the three-axis gyro drift estimation error can be kept within the range of 0.01 degrees/h, but individual tests are influenced by singular values, so that the calibration accuracy is obviously reduced, wherein the maximum x-axis gyro drift estimation error and the maximum y-axis gyro drift estimation error exceed 0.02 degrees/h, and the maximum z-axis gyro drift error reaches 1.5 degrees/h.
Fig. 3 is a graph of gyro drift estimation error obtained by the improved technique. In 100 simulation experiments, the calibration errors of the triaxial gyro drift are all kept within the range of 0.01 degrees/h, and no singular point exists.
Fig. 4 is an accelerometer zero offset estimation error obtained by the improved technique. In 100 simulation experiments, the calibration errors of the zero offset of the triaxial accelerometer are all kept within a range of 10 mug, and no singular point exists.
The embodiment effect shows that compared with the background technology, the technology is not influenced by an initial course angle, the occurrence of singular values is avoided, the gyro drift calibration accuracy is improved to 0.01 degrees/h, and the zero offset of the accelerometer can be calibrated at the same time.
Claims (1)
1. The zero offset error external field two-position calibration method of the inertial system is characterized by comprising the following steps of:
step 1, initially aligning a first position, namely horizontally placing an inertial navigation system, recording the inertial navigation system as the first position, standing for more than 600 seconds in the first position, and recording the average value of the output angular rate of the triaxial gyroscope in the time period And accelerometer output specific force mean valueAnd calculating an initial alignment pose matrix for the first positionThe attitude matrix contains misalignment angle errors
Wherein, N1＝U1×E1;
Step 2, attitude tracking, namely rotating an inertial navigation system around an azimuth axis by 180 degrees to reach a second position, solving an attitude differential equation by using gyro output data in the rotating process, and carrying out an attitude matrix at the moment of finishing rotationIs recorded as
Wherein: For the gesture matrix calculated in the rotation process, the initial value is Outputting an angular rate for the gyroscope; projection of the rotation angular velocity of the earth on an inertial navigation coordinate system;
Step 3, aligning the second position, namely keeping the second position stationary for more than 600 seconds, and recording the average value of the output angular rate of the triaxial gyroscope in the stationary time period And accelerometer output specific force mean valueAccording toAndCalculating an initial alignment pose matrix for the second positionBecause the index is 180 °, the attitude matrix contains misalignment angle errors
Wherein, N2＝U2×E2;
Step4, calculating a misalignment angle according to the gesture tracking matrixAnd a second position alignment pose matrixCalculating the misalignment angle
Calculating a corrected posture matrix
Step 5, zero offset calculation is carried out on the gyroscope and the accelerometer, and the calculation result is injected into the memory parameter of the inertial navigation system to finish zero offset error calibration:
calculating zero offset epsilon b of the gyroscope:
Calculating accelerometer zero offset
Wherein: And g n＝[0 0 -g]T is the projection of the rotation angular rate of the earth on a northeast geographic coordinate system, and g is a local gravitational acceleration module value.
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| CN104251708A (en) * | 2013-06-27 | 2014-12-31 | 北京自动化控制设备研究所 | New inertial navigation fast double-position alignment method |
| CN109959390A (en) * | 2018-12-26 | 2019-07-02 | 中国电子科技集团公司第二十研究所 | A double-position installation deviation compensation method for a rotary modulation system |
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