CN112362081A - Method for correcting mechanical displacement based on inertial navigation system - Google Patents

Abstract

The invention discloses a method for correcting mechanical displacement based on an inertial navigation system, which comprises an error correction mechanism adopting mechanical rotation, inertial navigation error characteristic analysis based on a mechanical rotation scheme, error suppression experiment and analysis, adaptive attenuation Kalman filtering and algorithm design, wherein the inertial navigation error characteristic analysis based on the mechanical rotation scheme comprises gyroscope scale factor influence analysis and gyroscope installation error influence analysis. The invention has the advantages that: the influence of errors caused by the gyroscope can be reduced through gyroscope scale factor influence analysis and gyroscope installation error influence analysis, errors of inertial devices of a micro-electro-mechanical system can be averaged through error suppression experiments and analysis by introducing an error modulation technology, adaptive attenuation Kalman filtering is introduced, and the correction weight of state estimation is adjusted by adjusting observation values at different moments so as to improve the convergence and estimation precision of a smoothing algorithm, so that the correction precision of mechanical displacement is more accurate.

Description

Method for correcting mechanical displacement based on inertial navigation system

Technical Field

The invention relates to the technical field of inertial navigation systems, in particular to a method for correcting mechanical displacement based on an inertial navigation system.

Background

An inertial navigation system, called inertial navigation system for short, is an autonomous navigation system which does not depend on external information and does not radiate energy to the outside. The working environment of the device not only comprises the air and the ground, but also can be underwater. The basic working principle of the inertial navigation system is based on Newton's law of mechanics, and by measuring the acceleration of a carrier in an inertial reference system, integrating the acceleration with time and transforming the acceleration into a navigation coordinate system, information such as speed, yaw angle and position in the navigation coordinate system can be obtained. The inertial navigation system is a navigation parameter calculation system which takes a gyroscope and an accelerometer as sensitive devices, establishes a navigation coordinate system according to the output of the gyroscope, and calculates the speed and the position of a carrier in the navigation coordinate system according to the output of the accelerometer. The inertial navigation system belongs to the dead reckoning navigation mode, i.e. the position of the next point is reckoned from the position of a known point according to the continuously measured course angle and speed of the moving body, so that the current position of the moving body can be continuously measured. A gyroscope in the inertial navigation system is used for forming a navigation coordinate system, so that a measuring axis of the accelerometer is stabilized in the coordinate system, and a course and an attitude angle are given; the accelerometer is used for measuring the acceleration of the moving body, the speed is obtained through the first integration of the time, and the displacement can be obtained through the first integration of the speed and the time.

However, the existing method for correcting mechanical displacement based on the inertial navigation system has some problems, firstly, the existing applicable micro-electro-mechanical system inertial device generally has the defect of large drift and becomes the main reason for influencing the independent and autonomous operation of the system, and the improvement of the performance of the inertia device of the micro-electro-mechanical system by improving the processing technology can not be realized in a short time, secondly, under the influence of an error source under the condition of no correction, the inertial navigation system can generate oscillation errors of multi-period modulation, thereby causing mechanical displacement of the element and lacking a high-precision attitude reference in practical application, the inertial navigation attitude error is difficult to directly measure, and can only be estimated through an error estimation algorithm under general conditions, however, the estimation algorithm has a large error, and therefore, a method for correcting mechanical displacement based on an inertial navigation system is provided.

Disclosure of Invention

The invention aims to solve the technical problems that the existing applicable micro-electro-mechanical system inertial device generally has the defect of large drift and becomes a main reason influencing the independent and autonomous work of the system, the performance of the micro-electro-mechanical system inertial device can be improved by improving the processing technology and still cannot be realized in a short time, the micro-electro-mechanical system inertial device is influenced by an error source under the condition of no correction, the inertial navigation system can generate multi-period modulation oscillation errors so as to cause the mechanical displacement of elements, a high-precision attitude reference is lacked in practical application, the direct measurement of the inertial navigation attitude errors is difficult, the estimation can be carried out only through an error estimation algorithm under the general condition, but the estimation algorithm has larger errors.

The invention adopts the following technical scheme to solve the technical problems: a method for correcting mechanical displacement based on an inertial navigation system comprises an error correction mechanism adopting mechanical rotation, inertial navigation error characteristic analysis based on a mechanical rotation scheme, error suppression experiments and analysis, adaptive attenuation Kalman filtering and algorithm design, wherein the inertial navigation error characteristic analysis based on the mechanical rotation scheme comprises gyroscope scale factor influence analysis and gyroscope installation error influence analysis, and the algorithm design comprises fixed point smoothing and inertial navigation initial error estimation and compensation.

Preferably, the error correction mechanism adopting mechanical rotation is substantially an error self-compensation technology, and the modulation of the slow-changing error of the inertial device by utilizing the periodic rotation of the inertial measurement unit is an effective method for realizing higher-precision navigation under the condition of the precision of the existing device. The inertial navigation system based on the error modulation technology has a structure change, the existence of the rotating mechanism causes the inertial measurement unit not to be fixedly connected with the carrier, but the calculation process of the whole system still adopts a strapdown algorithm. The essence of error modulation is that the inertial measurement element stays for the same time at a symmetrical position through the rotation of the inertial measurement unit, so that an error term caused by constant errors of a gyroscope and an accelerometer in an error propagation equation is zero or close to zero after integration, thereby reducing the accumulation of system errors and improving the navigation precision.

Preferably, the gyroscope scale factor influence analysis is that errors still exist after the MEMS scale factor is calibrated, and the scale factor also changes along with factors such as time, temperature and the like, which causes the MEMS inertial navigation system to always have the influence of inertial device errors in the actual working process.

Preferably, the gyroscope installation error influence analysis is an inertial measurement component, and 3 gyroscopes are installed according to a carrier coordinate axis. But the requirement cannot be met in the actual engineering, and installation errors exist. The installation error of the gyroscope can influence the attitude calculation. The installation error angle of each gyro can be represented by two parameters. During the continuous forward rotation process of the inertial measurement unit, similar to the analysis of the scale factor of the gyroscope, the mounting error of the gyroscope causes the output error of the gyroscope.

Preferably, the error suppression experiment and analysis are to verify the feasibility of the rotation of the inertia measurement unit for improving the calculation accuracy of the inertial navigation system, the inertia measurement unit of the micro-electro-mechanical system is installed in the center of an inertia test turntable, navigation experiments are respectively carried out under the conditions that the inertia measurement unit is in a static state, the inertia measurement unit rotates at angular speeds of 6 °/s, 12 °/s and 18 °/s, the experiment time is 10min, the latitude of the turntable is 420216 °, the longitude is 121.6703 ° and the sea level is 146m, the amplitude of the horizontal attitude angle of the carrier calculated under the rotation state of the inertia measurement unit is limited within 5 °, and the pitch angle and the roll angle obtained by the inertia measurement unit no matter how large the rotation angular speed is adopted are far better than the calculation value under the static state of the inertia measurement unit; the attitude periodic oscillation curve caused by different rotations of the inertial measurement unit is caused by the fact that a small angle exists in the horizontal direction when a micro-electromechanical system is installed on a rotary table, the larger the rotation speed of the inertial measurement unit is, the better the average effect of errors of an inertial device in a short time is, and therefore the larger the rotation speed of the inertial measurement unit is, the smaller the amplitude is.

Preferably, the adaptive attenuation Kalman filtering effectively inhibits the divergence problem of Kalman filtering, and ensures higher estimation precision, and the phenomena of abnormal filtering and even divergence frequently occur in Kalman filtering calculation, mainly due to inaccurate system modeling, inaccurate noise statistical model, absenteeism error accumulation and the like, so that the correction effect of the current measurement value on the estimation value is reduced, and the correction effect of the old measurement value on the estimation value is relatively increased. Kalman filtering is an effective estimation method for inhibiting filtering divergence by increasing the correction effect of a current observation value on an estimation value. In the case of system modeling distortion, the error of the traditional Kalman filter estimation value compared with the state true value is diverged.

Preferably, the fixed point smoothing is an optimal linear smoothing technology, that is, a filtering technology based on kalman filtering and smoothing. The method is widely applied to signal extraction, random noise filtering and the like. The optimal smoothing algorithm comprises fixed point smoothing, fixed interval smoothing and the like, wherein the fixed point smoothing utilizes all measurement values in a filtering interval to estimate a state value at a certain fixed moment, and the fixed interval smoothing utilizes all measurement values in a certain time interval to estimate all state values in the interval.

Preferably, the inertial navigation initial error estimation and compensation are one-path inertial navigation solution and one-path error derivation solution, the inertial navigation solution is normally performed according to a time sequence, the error derivation is performed after the initial attitude error and the inertial device error are estimated by the FPS algorithm, the error derivation is not limited by sampling, so that the inertial navigation solution can be quickly completed, and when the error derivation solution "catches up" with the first-path inertial navigation solution, the system error obtained by the error derivation can be used for compensating the result of the first-path inertial navigation solution.

Compared with the prior art, the invention provides a method for correcting mechanical displacement based on an inertial navigation system, which has the following beneficial effects:

1. according to the method for correcting the mechanical displacement based on the inertial navigation system, the error correction mechanism of mechanical rotation is adopted to compare the calculation errors of the micro-electromechanical system inertial navigation under the static condition and different rotation speeds of the inertial measurement unit, the larger the rotation angular speed of the inertial measurement unit is, the higher the relative accuracy of the system is, but the larger the rotation angular speed is combined with the actual working requirement, the larger the rotation angular speed is, and the burden of a mechanical structure and an accelerometer is increased. The influence of errors caused by the gyroscope can be reduced through gyroscope scale factor influence analysis and gyroscope installation error influence analysis, errors of inertia devices of a micro-electro-mechanical system can be averaged through error suppression experiments and analysis by introducing an error modulation technology, the defect that the applicable inertia devices of the micro-electro-mechanical system generally have large drift is overcome from another layer, the defect is a main reason influencing independent and autonomous work of the system, and the problem that the performance of the inertia devices of the micro-electro-mechanical system cannot be realized in a short time by improving a processing technology is solved.

2. The method for correcting the mechanical displacement based on the inertial navigation system estimates the attitude error and the gyro constant drift at a certain moment after the inertial navigation initial alignment is finished by using a fixed point smoothing algorithm, deduces the periodic oscillation error generated by the errors through the inertial navigation initial error estimation and compensation, compensates the inertial navigation output, introduces the adaptive attenuation Kalman filtering, and improves the convergence and the estimation precision of the smoothing algorithm by adjusting the correction weights of observation values at different moments to state estimation, so that the correction precision of the mechanical displacement is more accurate, and the problems that the attitude reference with higher precision is lacked in practical application, the inertial navigation attitude error is difficult to directly measure, the estimation can only be carried out through an error estimation algorithm under the general condition, but the estimation algorithm has larger error are solved.

Drawings

FIG. 1 is a system tree diagram of the present invention.

In the figure: 1. adopting an error correction mechanism of mechanical rotation; 2. analyzing inertial navigation error characteristics based on a mechanical rotation scheme; 21. analyzing the influence of the gyroscope scale factor; 22. analyzing the influence of the installation error of the gyroscope; 3. error suppression experiments and analysis; 4. self-adaptive attenuation Kalman filtering; 5. designing an algorithm; 51. the fixed point is smooth; 52. and estimating and compensating an inertial navigation initial error.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, a method for correcting mechanical displacement based on an inertial navigation system includes an error correction mechanism 1 using mechanical rotation, an inertial navigation error characteristic analysis 2 based on a mechanical rotation scheme, an error suppression experiment and analysis 3, an adaptive attenuation kalman filter 4, and an algorithm design 5, where the inertial navigation error characteristic analysis 2 based on the mechanical rotation scheme includes a gyroscope scale factor influence analysis 21 and a gyroscope installation error influence analysis 22, and the algorithm design 5 includes a fixed point smoothing 51 and an inertial navigation initial error estimation and compensation 52.

The error correction mechanism 1 adopting mechanical rotation is an error self-compensation technology, and the modulation of the slow-changing error of an inertial device is completed by utilizing the periodic rotation of an inertial measurement unit, so that the method is an effective method for realizing higher-precision navigation under the condition of the precision of the existing device. The inertial navigation system based on the error modulation technology has a structure change, the existence of the rotating mechanism causes the inertial measurement unit not to be fixedly connected with the carrier, but the calculation process of the whole system still adopts a strapdown algorithm. The essence of error modulation is that the inertial measurement element stays for the same time at a symmetrical position through the rotation of the inertial measurement unit, so that an error term caused by constant errors of a gyroscope and an accelerometer in an error propagation equation is zero or close to zero after integration, thereby reducing the accumulation of system errors and improving the navigation precision.

The gyroscope scale factor influence analysis 21 is that the MEMS scale factor still has errors after being calibrated, and the scale factor also changes along with factors such as time, temperature and the like, so that the MEMS inertial navigation system always has the influence of inertial device errors in the actual working process.

The gyroscope installation error influence analysis 22 is an inertial measurement component, and 3 gyroscopes should be installed according to a carrier coordinate axis. But the requirement cannot be met in the actual engineering, and installation errors exist. The installation error of the gyroscope can influence the attitude calculation. The installation error angle of each gyro can be represented by two parameters. During the continuous forward rotation process of the inertial measurement unit, similar to the analysis of the scale factor of the gyroscope, the mounting error of the gyroscope causes the output error of the gyroscope.

Error suppression experiment and analysis 3 is to verify the feasibility of the rotation of the inertia measurement unit for improving the solution precision of the inertial navigation system, the inertia measurement unit of the micro-electro-mechanical system is arranged in the center of an inertia test turntable, navigation experiments under the rotation conditions of the static state of the inertia measurement unit and the angular speeds of 6 DEG/s, 12 DEG/s and 18 DEG/s of the inertia measurement unit are respectively carried out, the experiment time is 10min, the latitude of the turntable is 420216 DEG, the longitude is 121.6703 DEG, and the sea level height is 146m, the amplitude of the horizontal attitude angle of a carrier solved under the rotation state of the inertia measurement unit is limited within 5 DEG, and the longitudinal and transverse rocking angles obtained by the inertia measurement unit at any rotation angular speed are far superior to the solution value of the inertia measurement unit under the static state; the attitude periodic oscillation curve caused by different rotations of the inertial measurement unit is caused by the fact that a small angle exists in the horizontal direction when a micro-electromechanical system is installed on a rotary table, the larger the rotation speed of the inertial measurement unit is, the better the average effect of errors of an inertial device in a short time is, and therefore the larger the rotation speed of the inertial measurement unit is, the smaller the amplitude is.

The self-adaptive attenuation Kalman filtering 4 effectively inhibits the divergence problem of Kalman filtering and ensures higher estimation precision, and the phenomena of abnormal filtering and even divergence frequently occur in Kalman filtering calculation, which are mainly caused by inaccurate system modeling, inaccurate noise statistical model, missing error accumulation and the like, so that the correction effect of the current measurement value on the estimation value is reduced, and the correction effect of the old measurement value on the estimation value is relatively increased. Kalman filtering is an effective estimation method for inhibiting filtering divergence by increasing the correction effect of a current observation value on an estimation value. In the case of system modeling distortion, the error of the traditional Kalman filter estimation value compared with the state true value is diverged.

The fixed point smoothing 51 is an optimal linear smoothing technique, that is, a filtering technique based on kalman filtering and smoothing. The method is widely applied to signal extraction, random noise filtering and the like. The optimal smoothing algorithm comprises fixed point smoothing, fixed interval smoothing and the like, wherein the fixed point smoothing utilizes all measurement values in a filtering interval to estimate a state value at a certain fixed moment, and the fixed interval smoothing utilizes all measurement values in a certain time interval to estimate all state values in the interval.

The initial inertial navigation error estimation and compensation 52 is one-way inertial navigation solution and one-way error derivation solution, the inertial navigation solution is normally performed according to the time sequence, the error derivation is performed after the initial attitude error and the inertial device error are estimated by the FPS algorithm, the error derivation is not limited by sampling, so that the method can be quickly completed, and when the error derivation solution "catches up" with the first-way inertial navigation solution, the system error obtained by the error derivation can be used for compensating the result of the first-way inertial navigation solution.

In summary, by comparing the error correction mechanism of mechanical rotation with the inertial navigation solution error of the mems at rest and different rotation speeds of the inertial measurement unit, it can be seen through comparison that the larger the rotation angular speed of the inertial measurement unit is, the higher the relative accuracy of the system is, but in combination with the actual working requirement, it is not necessary to select a very large rotation angular speed, since this will increase the burden of the mechanical structure and the accelerometer. The method comprises the steps of reducing the influence of errors caused by a gyroscope through gyroscope scale factor influence analysis and gyroscope installation error influence analysis, averaging the errors of inertial devices of a micro-electro-mechanical system through error suppression experiments and analysis by introducing an error modulation technology, estimating attitude errors and gyroscope constant drift at a certain moment after inertial navigation initial alignment is finished by using a fixed point smoothing algorithm, deducing periodic oscillation errors generated by the errors through inertial navigation initial error estimation and compensation, compensating inertial navigation output, introducing self-adaptive attenuation Kalman filtering, and improving the convergence and estimation accuracy of the smoothing algorithm by adjusting the correction weight of state estimation through adjusting observation values at different moments, so that the correction accuracy of mechanical displacement is more accurate.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (8)

1. A method for correcting mechanical displacement based on an inertial navigation system is characterized by comprising the following steps: the method comprises an error correction mechanism (1) adopting mechanical rotation, inertial navigation error characteristic analysis (2) based on a mechanical rotation scheme, an error suppression experiment and analysis (3), adaptive attenuation Kalman filtering (4) and algorithm design (5), wherein the inertial navigation error characteristic analysis (2) based on the mechanical rotation scheme comprises gyroscope scale factor influence analysis (21) and gyroscope installation error influence analysis (22), and the algorithm design (5) comprises fixed point smoothing (51) and inertial navigation initial error estimation and compensation (52).

2. The method for correcting the mechanical displacement based on the inertial navigation system is characterized in that: the error correction mechanism (1) adopting mechanical rotation is an error self-compensation technology in essence, and the modulation of the slow-changing error of an inertial device is completed by utilizing the periodic rotation of an inertial measurement unit, so that the method is an effective method for realizing higher-precision navigation under the condition of the precision of the existing device. The inertial navigation system based on the error modulation technology has a structure change, the existence of the rotating mechanism causes the inertial measurement unit not to be fixedly connected with the carrier, but the calculation process of the whole system still adopts a strapdown algorithm. The essence of error modulation is that the inertial measurement element stays for the same time at a symmetrical position through the rotation of the inertial measurement unit, so that an error term caused by constant errors of a gyroscope and an accelerometer in an error propagation equation is zero or close to zero after integration, thereby reducing the accumulation of system errors and improving the navigation precision.

3. The method for correcting the mechanical displacement based on the inertial navigation system is characterized in that: the gyroscope scale factor influence analysis (21) is that errors still exist after the MEMS scale factor is calibrated, and the scale factor can change along with factors such as time, temperature and the like, so that the influence of inertial device errors always exists in the MEMS inertial navigation system in the actual working process.

4. The method for correcting the mechanical displacement based on the inertial navigation system is characterized in that: and the gyroscope installation error influence analysis (22) is an inertia measurement component, and 3 gyroscopes are installed according to a carrier coordinate axis. But the requirement cannot be met in the actual engineering, and installation errors exist. The installation error of the gyroscope can influence the attitude calculation. The installation error angle of each gyro can be represented by two parameters. During the continuous forward rotation process of the inertial measurement unit, similar to the analysis of the scale factor of the gyroscope, the mounting error of the gyroscope causes the output error of the gyroscope.

5. The method for correcting the mechanical displacement based on the inertial navigation system is characterized in that: the error inhibition experiment and analysis (3) is to verify the feasibility of the rotation of the inertia measurement unit for improving the calculation precision of the inertial navigation system, the inertia measurement unit of the micro-electro-mechanical system is arranged in the center of an inertia test turntable, navigation experiments under the conditions that the inertia measurement unit is in a static state and the inertia measurement unit rotates at angular speeds of 6 DEG/s, 12 DEG/s and 18 DEG/s are respectively carried out, the experiment time is 10min, the latitude of the turntable is 420216 DEG, the longitude of the turntable is 121.6703 DEG and the sea level height of the turntable is 146m, the amplitude of the horizontal attitude angle of a carrier calculated under the rotation state of the inertia measurement unit is limited within 5 DEG, and the longitudinal and transverse rocking angles obtained by the inertia measurement unit no matter how large the rotation angular speed is adopted are far better than the calculation value of the inertia measurement unit in the static state; the attitude periodic oscillation curve caused by different rotations of the inertial measurement unit is caused by the fact that a small angle exists in the horizontal direction when a micro-electromechanical system is installed on a rotary table, the larger the rotation speed of the inertial measurement unit is, the better the average effect of errors of an inertial device in a short time is, and therefore the larger the rotation speed of the inertial measurement unit is, the smaller the amplitude is.

6. The method for correcting the mechanical displacement based on the inertial navigation system is characterized in that: the self-adaptive attenuation Kalman filtering (4) effectively inhibits the divergence problem of Kalman filtering, ensures higher estimation precision, and frequently causes the phenomena of abnormal filtering and even divergence in Kalman filtering calculation, mainly because of inaccurate system modeling, inaccurate noise statistical model, absenteeism error accumulation and the like, so that the correction effect of the current measurement value on the estimation value is reduced, and the correction effect of the old measurement value on the estimation value is relatively increased. Kalman filtering is an effective estimation method for inhibiting filtering divergence by increasing the correction effect of a current observation value on an estimation value. In the case of system modeling distortion, the error of the traditional Kalman filter estimation value compared with the state true value is diverged.

7. The method for correcting the mechanical displacement based on the inertial navigation system is characterized in that: the fixed point smoothing (51) is an optimal linear smoothing technology, namely a filtering technology based on Kalman filtering and smoothing. The method is widely applied to signal extraction, random noise filtering and the like. The optimal smoothing algorithm comprises fixed point smoothing, fixed interval smoothing and the like, wherein the fixed point smoothing utilizes all measurement values in a filtering interval to estimate a state value at a certain fixed moment, and the fixed interval smoothing utilizes all measurement values in a certain time interval to estimate all state values in the interval.

8. The method for correcting the mechanical displacement based on the inertial navigation system is characterized in that: the inertial navigation initial error estimation and compensation (52) is one-path inertial navigation calculation and one-path error derivation calculation, the inertial navigation calculation is normally carried out according to a time sequence, the error derivation is carried out after the initial attitude error and the inertial device error are estimated by an FPS algorithm, the error derivation is not limited by sampling, so that the inertial navigation calculation can be quickly completed, and when the error derivation calculation catches up with the first-path inertial navigation calculation, the system error obtained by the error derivation can be used for compensating the result of the first-path inertial navigation calculation.

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