Night inertial, starlight and polarization combined navigation method and device considering measurement failure

Abstract

The application discloses a night inertia, starlight and polarization combined navigation method and device considering measurement failure, and belongs to the technical field of autonomous navigation. The method comprises the following steps: a moon vector in a carrier coordinate system b is calculated, a corresponding moon vector in a navigation coordinate system n and an optical axis vector of a star sensor are calculated; a measurement vector error is calculated, a state vector is defined, and a state equation of a combined navigation system is established; according to whether the inertial navigation, the star sensor and the polarization information participate in measurement or not, three different modes of measurement matrixes, namely, only inertia, inertia and starlight and inertia and starlight and polarization, are obtained, a measurement model is established, and three types of filtering modes are obtained; in the filtering process of the combined navigation system, when measurement is updated, a residual-based chi-square test method is used for fault diagnosis, and hierarchical switching is carried out among different modes, so that optimal combined navigation attitude estimation is realized. The application improves the robustness of the system and realizes continuous and reliable navigation under complex weather conditions.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of satellite autonomous navigation, and particularly relates to a night inertial, starlight and polarization combined navigation method and device considering measurement failure. BACKGROUND

[0002] With the development of autonomous navigation technology, the celestial navigation system taking star sensor as the core has been widely applied. The star sensor realizes attitude solution through star point sensing and star map identification, and has significant advantages such as no error accumulation and anti-electromagnetic interference. However, most of the traditional star sensors adopt narrow field of view design (field of view angle < 20°), which can improve the resolution of the obtained observation star map, but is easily affected by cloud layer, vegetation or building and other interference to cause observation failure. The measurement data of the sensor in abnormal state restricts its application in actual engineering.

[0003] Bionic polarization navigation can obtain navigation information through sensing the distribution pattern of sky polarization light. In the night, the sky polarization light is mainly derived from moonlight, and generally the full-sky polarization data is collected through an image type polarization sensor with a field of view angle > 170°, and then the heading solution is realized. The bionic polarization navigation also has advantages such as passive and no radiation, and error not accumulated with time. Inspired by the fact that the natural scarab beetle cooperatively navigates through starlight and polarization light clues, the night combined navigation system integrating celestial navigation and polarization navigation gradually becomes a research hotspot.

[0004] However, the existing method does not consider the situation that the measurement precision of the sensor is reduced or even failed due to the low light intensity and poor visibility in the complex scene in the night. SUMMARY

[0005] To solve the above technical problems, the application adopts the following technical solutions:

[0006] A night inertial, starlight and polarization combined navigation method considering measurement failure, comprising:

[0007] Step 1, measuring the polarization information under the current attitude by using the polarization sensor, and calculating the moon vector in the carrier coordinate system b ; obtaining the corresponding moon vector in the navigation coordinate system n according to the astronomical almanac; measuring the optical axis vector of the sensor pointing in the n coordinate system by using the star sensor;

[0008] Step 2, obtaining the predicted value of the starlight optical axis vector and the predicted value of the moon vector based on the inertial attitude matrix ; respectively calculating the difference between the measurement vector and the predicted value of the star sensor and the polarization sensor and , the measurement vector error ;

[0009] Step 3, the measurement vector error is taken as the system state, combined with the inertial navigation error equation, the state vector is defined, and the state equation of the integrated navigation system is established;

[0010] Step 4, according to whether the inertial navigation, star sensor and polarization information participates in measurement, three different modes of measurement matrixes of only inertia, inertia and starlight, and inertia, starlight and polarization are obtained , and , the measurement model is established, and three types of filtering modes are obtained: I mode, IC mode and ICP mode;

[0011] Step 5, in the filtering process of the integrated navigation system, at the time of measurement update, the chi-square test method based on residual is used for fault diagnosis, and hierarchical switching among different modes is performed to realize optimal integrated navigation attitude estimation.

[0012] A night-time inertial, starlight and polarization integrated navigation device considering measurement failure, comprising:

[0013] A vector calculation module, which calculates the moon vector in the carrier coordinate system b by measuring the polarization information under the current attitude by using the polarization sensor ; obtains the corresponding moon vector in the navigation coordinate system n according to the astronomical almanac ; and obtains the optical axis vector of the sensor pointing in the n system by measuring by using the star sensor ;

[0014] A measurement vector error acquisition module, which obtains the predicted value of the star sensor optical axis vector and the predicted value of the moon vector based on the inertial attitude matrix ; calculates the difference between the measurement vector and the predicted value of the star sensor and the polarization sensor respectively and , and obtains the measurement vector error ;

[0015] A state equation establishment module, which takes the measurement vector error as the system state, combines the inertial navigation error equation, defines the state vector , and establishes the state equation of the integrated navigation system;

[0016] A filtering mode acquisition module, which obtains three different modes of measurement matrixes of only inertia, inertia and starlight, and inertia, starlight and polarization according to whether the inertial navigation, star sensor and polarization information participates in measurement , and Three measurement models were established, and three types of filtering modes were obtained: I mode, IC mode, and ICP mode.

[0017] In the filtering module of the integrated navigation system, during measurement updates, residual-based filtering is used. The chi-square test method is used for fault diagnosis, and different modes are switched in stages to achieve optimal integrated navigation attitude estimation.

[0018] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the steps of the nighttime inertial, starlight, and polarization combined navigation method that takes into account measurement failures.

[0019] A non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the nighttime inertial, starlight, and polarization combined navigation method considering measurement failures.

[0020] The present invention has the following beneficial effects:

[0021] (1) The present invention directly incorporates the original observation vectors of the star sensor and polarization sensor into the integrated navigation system, avoiding the additional errors introduced by the sensors in the independent attitude calculation process; at the same time, the chi-square test is used to diagnose the measurement faults, thereby continuously outputting reliable carrier attitude information and improving the accuracy and autonomy of the navigation system.

[0022] (2) In view of the risk of intermittent observation failure of star sensors and polarization sensors in complex nighttime scenarios, this invention designs a hierarchical navigation mode architecture and, in conjunction with a real-time fault detection and intelligent switching mechanism, performs hierarchical switching of different navigation modes based on the chi-square test results, improves the robustness of the system, and realizes continuous and reliable navigation under complex weather conditions. Attached Figure Description

[0023] Figure 1 This is a flowchart of the nighttime inertial, starlight, and polarization combined navigation method of the present invention, taking into account measurement failures. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0025] like Figure 1As shown, the nighttime inertial, starlight, and polarization combined navigation method of the present invention, which considers measurement failures, includes:

[0026] Step 1: Measure the polarization information under the current attitude using a polarization sensor, and calculate the moon vector in the carrier coordinate system b. Moon vector output by polarization sensor Represented as:

[0027] ;

[0028] in, and These represent the moon's altitude and azimuth, respectively.

[0029] The lunar vector in the navigation coordinate system n can be obtained from the astronomical almanac. Specifically, based on the clock and astronomical calendar information built into the carrier, the right ascension and declination of the moon in the navigation coordinate system n at the current moment can be obtained, and thus the moon's vector in the n-system can be obtained. .

[0030] The optical axis vector pointed to by the sensor in the n-system is obtained by measuring the star sensor. Specifically, starlight information in the b-system is obtained by measuring starlight using a star sensor. Through star chart matching, the right ascension and declination of the star sensor's central optical axis in the n-system can be obtained, thus yielding the star sensor's optical axis vector in the n-system. .

[0031] Step 2, based on the inertial navigation attitude array The predicted value of the star-sensitive optical axis vector can be obtained. Predicted values ​​of lunar vectors Calculate the difference between the measured vector and the predicted value of the star sensor and polarization sensor, respectively. and The measurement vector error is obtained. ;

[0032] Step 2.1, based on the inertial navigation attitude array Obtain the predicted value of the star-sensitive optical axis vector. Star-sensitive optical axis vector in the b system And the star-sensitive optical axis vector in the n-system The conversion relationship between them is as follows:

[0033] ;

[0034] in, To transform the vector from the navigation frame to the inertial navigation computation frame, the direction cosine matrix is... It is the identity matrix. Let be the antisymmetric matrix of the attitude misalignment angle vector. This represents the computational frame obtained from inertial navigation calculations.

[0035] Step 2.2, based on the inertial navigation attitude array The estimated predicted value of the star sensor optical axis vector Represented as:

[0036] ;

[0037] in, Inertial navigation attitude array The inverse transform of .

[0038] Step 2.3, obtain the star sensor measurement vector error:

[0039] ;

[0040] For a star sensor installed in the b-system, the star sensor optical axis vector is the observation direction of the star sensor, which can be expressed as follows in the b-system: .

[0041] Step 2.4, based on the inertial navigation attitude array Obtain the predicted value of the lunar vector The lunar vector in the n-system obtained from the astronomical almanac ,pass Obtain the predicted lunar vector value in the b-system. The lunar vector measured by the polarization sensor. Predicted lunar vector values ​​under the b system The difference is the measurement error of the lunar vector:

[0042] ;

[0043] in, This means constructing a skew-symmetric matrix from the vectors. This is the attitude misalignment angle.

[0044] Step 2.5: For the inertial, starlight, and polarization-based integrated navigation system, calculate the difference between the measurement vectors and predicted values ​​of the star sensor and polarization sensor, respectively. and The measurement vector error is obtained. .

[0045] Step 3, measure the vector error As the system state, combined with the inertial navigation error equation, a state vector is defined. And establish the state equations. In inertial, starlight, and polarization combined navigation systems, based on the inertial navigation error equations and combined with measurement vector errors... The system status can be obtained as follows:

[0046] ;

[0047] in, For the attitude misalignment angle, For speed error, For positional error, For gyroscope random drift, This refers to the random bias of the accelerometer.

[0048] Further obtain the state equation of the integrated navigation system:

[0049] ;

[0050] in, The state matrix of the inertial, starlight, and polarization combined navigation system. This is the noise factor matrix for an inertial, starlight, and polarization-based integrated navigation system. This is the process noise vector.

[0051] Step 4: Based on whether inertial navigation, star sensing, and polarization information are involved in the measurement, obtain the measurement matrices for three different modes: inertial only, inertial and starlight, and inertial, starlight, and polarization. , and Three measurement models were established to obtain the corresponding I, IC, and ICP filtering modes.

[0052] Because the update frequencies of inertial, star-sensor, and polarization information differ, three combination modes are designed based on whether inertial navigation, star-sensor, and polarization information participate in the measurement. Based on the type of navigation information involved in the measurement, measurement matrices are obtained for three different modes: inertial only, inertial and starlight, and inertial, starlight, and polarization. , and .

[0053] Because inertial information is updated most frequently, there exists a Mode I where only inertial measurements are updated. In this mode, only the accelerometer measurements in the inertial navigation system are updated, and the corresponding measurement model is:

[0054] ;

[0055] in, Measurement noise in I mode, It can be represented as:

[0056] ;

[0057] in, It represents the acceleration due to gravity.

[0058] The star sensor's update frequency is higher than that of the polarization sensor, resulting in an IC mode where both inertial measurement and star sensor measurement updates occur simultaneously. In this mode, in addition to updating inertial measurement information, star sensor measurement information is also updated. The corresponding measurement model in IC mode is:

[0059] ;

[0060] in, Measurement noise in IC mode . It can be represented as:

[0061] ;

[0062] in, This indicates that the vectors are constructed into antisymmetric matrices.

[0063] When inertial, star-sensor, and polarization information are updated simultaneously, ICP mode can be used; in ICP mode, the corresponding measurement model is:

[0064] ;

[0065] in, Measurement noise in ICP mode, ; It can be represented as:

[0066] ;

[0067] In the designed integrated navigation system, the inertial navigation system serves as the reference system and is combined with navigation information from the star sensor and polarization sensor. Based on the measurement information, the system is updated with three filtering modes: I, IC, and ICP.

[0068] Step 5: During the filtering process of the integrated navigation system, when updating measurements, a residual-based method is used. The chi-square test method is used for fault diagnosis, and different modes are switched in stages to achieve optimal integrated navigation attitude estimation.

[0069] Considering that star sensors and polarization sensors may be affected by the environment, such as obstruction, clouds, fog, artificial light, etc., which may cause sensor failure or accuracy degradation, fault detection is performed on IC and ICP modes that include star sensor measurement updates and polarization measurement updates.

[0070] When the navigation system operates in ICP mode, filtering is performed based on the state equation and measurement equation of this mode, and a residual-based filtering method is adopted. The chi-square test method is used for fault diagnosis. If the test passes, ICP mode is run. If the test fails, it switches to IC mode and performs fault diagnosis again based on the residual. The chi-square test method is used. If the test passes, the IC mode is maintained; otherwise, it is further downgraded to I mode.

[0071] When the navigation system operates in IC mode, it adopts a residual-based approach. The chi-square test method is used for fault diagnosis. If the test passes, the IC mode is maintained; if it fails, the mode is switched to I mode.

[0072] Furthermore, based on the established inertial, starlight, and polarization combined navigation model, and based on the combined modes under different scenarios and fault conditions, Kalman filtering is used to estimate the three-dimensional attitude misalignment angle during measurement updates. The optimal attitude estimate is obtained through multi-mode switching, thereby realizing the attitude correction of the carrier.

[0073] The contents not described in detail in this specification are common knowledge to those skilled in the art.

[0074] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The embodiments of the present invention can be implemented using various computer languages.

[0075] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0076] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0077] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0078] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0079] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0080] The above description is merely an embodiment of the present invention and does not limit the scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related system fields, are similarly included within the protection scope of the present invention.

Claims

1. A nighttime inertial, starlight, and polarization combined navigation method considering measurement failures, characterized in that, include: Step 1: Measure the polarization information under the current attitude using a polarization sensor, and calculate the moon vector in the carrier coordinate system b. ; Obtain the corresponding lunar vector in the navigation coordinate system n based on the astronomical almanac. The optical axis vector pointed to by the sensor in the n-system is obtained by measuring the star sensor. ; Step 2, based on the inertial navigation attitude array Obtain the predicted value of the star-sensitive optical axis vector. Predicted values ​​of lunar vectors Calculate the difference between the measured vector and the predicted value of the star sensor and polarization sensor, respectively. and The measurement vector error is obtained. ; Step 3, measure the vector error As the system state, combined with the inertial navigation error equation, a state vector is defined. And establish the state equations of the integrated navigation system; Step 4: Based on whether inertial navigation, star sensing, and polarization information are involved in the measurement, obtain the measurement matrices for three different modes: inertial only, inertial and starlight, and inertial, starlight, and polarization. , and A measurement model was established to obtain three types of filtering modes: I mode, IC mode, and ICP mode. Step 5: During the filtering process of the integrated navigation system, when updating measurements, a residual-based method is used. The chi-square test method is used for fault diagnosis, and different modes are switched in stages to achieve optimal integrated navigation attitude estimation.

2. The nighttime inertial, starlight, and polarization combined navigation method considering measurement failures according to claim 1, characterized in that, Step 5 also includes: based on the established inertial, starlight and polarization combined navigation model, and based on the combined modes under different scenarios and fault conditions, Kalman filtering is used to estimate the three-dimensional attitude misalignment angle during measurement updates, and the optimal attitude estimate is obtained through hierarchical switching between different modes to achieve attitude correction of the carrier.

3. The nighttime inertial, starlight, and polarization combined navigation method considering measurement failures according to claim 1, characterized in that, In step 1, the moon vector Represented as: ； in, and These represent the moon's altitude and azimuth, respectively.

4. The nighttime inertial, starlight, and polarization combined navigation method considering measurement failures according to claim 3, characterized in that, Step 2 includes: Step 2.1, based on the inertial navigation attitude array Obtain the predicted value of the star-sensitive optical axis vector. Star-sensitive optical axis vector in the b system And the star-sensitive optical axis vector in the n-system The conversion relationship between them is as follows: ； in, To transform the vector from the navigation frame to the inertial navigation computation frame, the direction cosine matrix is... It is the identity matrix. Let be the antisymmetric matrix of the attitude misalignment angle vector. This represents the computational frame obtained from inertial navigation calculations; Step 2.2, based on the inertial navigation attitude array The estimated predicted value of the star sensor optical axis vector Represented as: ； in, Inertial navigation attitude array inverse transform; Step 2.3, obtain the star sensor measurement vector error: ； For a star sensor installed in the b-system, the star sensor optical axis vector is the observation direction of the star sensor, which is represented as follows in the b-system: ; Step 2.4, based on the inertial navigation attitude array Obtain the predicted value of the lunar vector The lunar vector in the n-system obtained from the astronomical almanac ,pass Obtain the predicted lunar vector value in the b-system. The lunar vector measured by the polarization sensor Predicted lunar vector values ​​under the b system The difference is the measurement error of the lunar vector: ； in, This means constructing a skew-symmetric matrix from the vectors. This refers to the angle of attitude misalignment. Step 2.5: Calculate the difference between the measurement vector and the predicted value of the star sensor and polarization sensor, respectively. and The measurement vector error is obtained. .

5. The nighttime inertial, starlight, and polarization combined navigation method considering measurement failure according to claim 4, characterized in that, In step 3, within the inertial, starlight, and polarization integrated navigation system, based on the inertial navigation error equation and combined with the measurement vector error... The system status is as follows: ； in, For the attitude misalignment angle, For speed error, For positional error, For gyroscope random drift, This refers to random bias in accelerometer readings. This leads to the state equation of the integrated navigation system: ； in, The state matrix of the inertial, starlight, and polarization combined navigation system. This is the noise factor matrix for an inertial, starlight, and polarization-based integrated navigation system. This is the process noise vector.

6. The nighttime inertial, starlight, and polarization combined navigation method considering measurement failures according to claim 5, characterized in that, Step 4 includes: obtaining the measurement matrices for three different modes based on the type of navigation information involved in the measurement: Mode I (inertial update only), Mode IC (inertial and starlight update), and Mode ICP (inertial, starlight, and polarization update). , and ; The measurement model corresponding to Mode I is: ； in, The measurement noise in mode I, where for: ； in, It is the acceleration due to gravity; The measurement model corresponding to IC mode is: ； in, Measurement noise in IC mode , for: ； in, This means constructing a skew-symmetric matrix from the vectors; The measurement model corresponding to ICP mode is: ； in, Measurement noise in ICP mode, , for: 。 7. The nighttime inertial, starlight, and polarization combined navigation method considering measurement failures according to claim 6, characterized in that, Step 5 includes: When the navigation system is running in ICP mode, filtering is performed based on the state equation and measurement equation of this mode, and a residual-based filtering method is adopted. The chi-square test method is used for fault diagnosis; if the test passes, ICP mode is run; if the test fails, it switches to IC mode and performs fault diagnosis again based on the residual. The chi-square test method is used. If the test passes, the IC mode is maintained; otherwise, it is further downgraded to I mode. When the navigation system operates in IC mode, it adopts a residual-based approach. The chi-square test method is used for fault diagnosis. If the test passes, the IC mode is maintained; if it fails, the mode is switched to I mode.

8. A nighttime inertial, starlight, and polarization combined navigation device considering measurement failure, characterized in that, include: The vector calculation module uses a polarization sensor to measure polarization information under the current attitude and calculates the moon vector in the carrier coordinate system b. ; Obtain the corresponding lunar vector in the navigation coordinate system n based on the astronomical almanac. The optical axis vector pointed to by the sensor in the n-system is obtained by measuring the star sensor. ; Measurement vector error acquisition module, based on inertial navigation attitude array Obtain the predicted value of the star-sensitive optical axis vector. Predicted values ​​of lunar vectors Calculate the difference between the measured vector and the predicted value of the star sensor and polarization sensor, respectively. and The measurement vector error is obtained. ; The state equation establishment module will establish the measurement vector error. As the system state, combined with the inertial navigation error equation, a state vector is defined. And establish the state equations of the integrated navigation system; The filter mode acquisition module obtains measurement matrices for three different modes: inertial only, inertial and starlight, and inertial, starlight, and polarization, depending on whether inertial navigation, star-sensor, and polarization information are involved in the measurement. , and Three measurement models were established, and three types of filtering modes were obtained: I mode, IC mode, and ICP mode. In the filtering module of the integrated navigation system, during measurement updates, residual-based filtering is used. The chi-square test method is used for fault diagnosis, and different modes are switched in stages to achieve optimal integrated navigation attitude estimation.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the nighttime inertial, starlight, and polarization combined navigation method considering measurement failures as described in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the nighttime inertial, starlight, and polarization combined navigation method as described in any one of claims 1 to 7, taking into account measurement failures.

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