Inertial navigation system calibration method and device based on cold atom interferometer

Abstract

The invention discloses an inertial navigation system calibration method and device based on a cold atom interferometer, and relates to the technical field of inertial navigation, guidance and control, an accelerometer and a gyroscope are used for collecting original data and correcting errors, and then calibration is carried out by combining the earth gravity acceleration and rotation angular velocity collected by the cold atom interferometer. And through calculation of an attitude rate differential equation and a displacement angular rate differential equation and attitude fusion, accurate attitude output is obtained. According to the invention, the pose measurement precision is greatly improved; the system has an autonomous traceability, and gets rid of the dependence of traditional calibration on laboratory equipment or specific devices; the rearranged algorithm enhances the precision of long-time navigation in a complex environment, and is suitable for long-endurance and combined navigation systems; the online calibration function of the calibration system can correct system parameter drift in real time, continuous high-precision operation of the navigation system is guaranteed, and the overall performance and reliability of the inertial navigation system are effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of inertial navigation, guidance and control, and more particularly to a method and device for calibrating an inertial navigation system based on a cold atom interferometer. Background Art

[0002] At present, the high-precision inertial-based integrated navigation system is composed of INS (Inertial Navigation Unit) and GNSS (Global Navigation Sallite System), which can provide high-frequency and high-precision time and space reference information for long-endurance strategic weapons. In the case of GNSS denial, the inertial navigation system is a completely autonomous position and attitude calculation system, and the positioning and attitude accuracy will decrease over time. In addition, the parameters of the inertial navigation system itself will drift over time, affecting the accuracy of position and attitude measurement, and must be calibrated regularly. However, the traditional calibration method usually requires the inertial navigation system to be disassembled from the equipment and sent back to the laboratory to complete the calibration on a high-precision position rate turntable; or a rotational modulation inertial navigation system is used. Although it does not need to be disassembled, the calibration accuracy is subject to the accuracy of the rotational modulation device.

[0003] Therefore, how to provide a calibration method that can be independently traced and has good accuracy and stability is an urgent problem that technicians in this field need to solve. Summary of the invention

[0004] In view of this, the present invention provides an inertial navigation system calibration method and device based on cold atom interferometer to solve the problems existing in the background technology.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A method for calibrating an inertial navigation system based on a cold atom interferometer, comprising:

[0007] Collect raw measurement data information through accelerometers and gyroscopes;

[0008] Correct the errors in the original measurement data to obtain error-compensated gyroscope data and accelerometer data;

[0009] The Earth's gravitational acceleration and the Earth's rotational angular velocity are collected through a cold atom interferometer, and the error-compensated gyroscope data and accelerometer data are calibrated;

[0010] The calibrated gyroscope data enters the attitude rate differential equation, and the attitude rate is calculated as the first attitude information; and the coordinate conversion matrix is ​​used to convert between the carrier coordinate system and the navigation coordinate system;

[0011] The accelerometer data is combined with the attitude rate output by the attitude rate differential equation and the data collected by the cold atom interferometer, and the displacement angular rate is calculated after eliminating the harmful accelerometer velocity integral processing;

[0012] The displacement angular rate is used as the input of the displacement angular rate differential equation to obtain the second posture information;

[0013] The first pose information is fused with the second pose information to obtain the pose output.

[0014] Optionally, the accelerometer is used to measure the specific force information of the carrier in each direction, and the gyroscope is used to measure the angular velocity information of the carrier; in the carrier coordinate system b, the original measurement output of the accelerometer is expressed as f b , the raw measurement output of the gyroscope is expressed as Where i represents the inertial coordinate system and b represents the carrier coordinate system.

[0015] Optionally, for the gyroscope, its error compensation model is expressed as:

[0016]

[0017] in, is the gyro output after error compensation, is the gyroscope bias error vector, S g is the gyroscope scale factor matrix, ∈ g is the random error vector of the gyroscope.

[0018] Optionally, for the accelerometer, the error compensation model is:

[0019]

[0020] in, is the accelerometer output after error compensation, is the accelerometer bias error vector, S a is the accelerometer scale factor matrix, ∈ a is the random error vector of the accelerometer.

[0021] Optional, error-compensated gyroscope data Enter the attitude rate differential equation, which describes the relationship between the carrier attitude and time, and is expressed in the carrier coordinate system as:

[0022]

[0023] in, Represents the time derivative of the coordinate transformation matrix from the carrier coordinate system b to the navigation coordinate system n, is the coordinate transformation matrix from the carrier coordinate system b to the navigation coordinate system n, Is The antisymmetric matrix is ​​formed; by solving the differential equation, the attitude rate is calculated As the first pose information; at the same time, through the coordinate transformation matrix Conversion is performed between the carrier coordinate system and the navigation coordinate system to achieve unified processing of data in different coordinate systems.

[0024] Optional, accelerometer data Combined with the attitude rate output of the attitude rate differential equation The data collected by the cold atom interferometer; first, the harmful accelerometer velocity integral is eliminated; the accelerometer data after eliminating the harmful accelerometer velocity integral is Then, the displacement angular rate ω is calculated according to the following relationship d :

[0025]

[0026] in, is the coordinate transformation matrix from the carrier coordinate system b to the navigation coordinate system n, g b is the representation of the Earth's gravitational acceleration in the carrier coordinate system, v b It is the expression of the carrier's velocity in the carrier coordinate system.

[0027] Optionally, the displacement angular rate ω d As the input of the displacement angular rate differential equation; the displacement angular rate differential equation describes the relationship between the displacement angle and time, expressed as:

[0028]

[0029] By solving the differential equation, we can get the second pose information

[0030] Optionally, the fused pose information P is calculated by the following formula:

[0031]

[0032] In the formula, is the first pose information, is the second pose information, w1 and w2 are the weights corresponding to the first pose information and the second pose information respectively.

[0033] An inertial navigation system calibration system based on a cold atom interferometer comprises: a cold atom interferometer and a calibration system; the cold atom interferometer is composed of a vacuum unit, an electric control unit, an optical unit, and an autonomous traceability unit; the calibration system realizes online calibration of the inertial navigation system through a relative measurement and calibration method.

[0034] It can be known from the above technical scheme that, compared with the prior art, the present invention discloses a method and device for calibrating an inertial navigation system based on a cold atom interferometer, which provides accurate earth gravity acceleration and earth rotation angular velocity for a strapdown inertial navigation system through a cold atom interferometer, further improving the strapdown inertial navigation system's attitude measurement accuracy. The present invention rearranges the strapdown inertial navigation attitude solution algorithm, greatly improving the strapdown inertial navigation system's attitude measurement accuracy, while improving the long-term high-precision navigation capability in a complex environment, and can be applied to long-duration high-precision inertial navigation, and can also be applied to a combined navigation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0036] Figure 1 A schematic diagram of the structure provided by the present invention. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] The embodiment of the present invention discloses a method for calibrating an inertial navigation system based on a cold atom interferometer, such as Figure 1 As shown, including:

[0039] Collect raw measurement data information through accelerometers and gyroscopes;

[0040] Correct the errors in the original measurement data to obtain error-compensated gyroscope data and accelerometer data;

[0041] The Earth's gravitational acceleration and the Earth's rotational angular velocity are collected through a cold atom interferometer, and the error-compensated gyroscope data and accelerometer data are calibrated;

[0042] The calibrated gyroscope data enters the attitude rate differential equation, and the attitude rate is calculated as the first attitude information; and the coordinate conversion matrix is ​​used to convert between the carrier coordinate system and the navigation coordinate system;

[0043] The accelerometer data is combined with the attitude rate output by the attitude rate differential equation and the data collected by the cold atom interferometer, and the displacement angular rate is calculated after eliminating the harmful accelerometer velocity integral processing;

[0044] The displacement angular rate is used as the input of the displacement angular rate differential equation to obtain the second posture information;

[0045] The first pose information is fused with the second pose information to obtain the pose output.

[0046] In a specific embodiment, the elimination of harmful accelerometer velocity integral processing is mainly due to the fact that the accelerometer measurement contains other interfering accelerations besides gravity and carrier motion acceleration, such as carrier vibration acceleration, etc. When eliminating harmful accelerometer velocity integrals, a model-based method or an adaptive filtering method can be used. For example, by establishing a carrier vibration model, the acceleration component caused by vibration is identified and deducted from the original accelerometer data according to the vibration frequency and amplitude characteristics. Alternatively, an adaptive Kalman filter is used to dynamically adjust the filter parameters according to the statistical characteristics of the measurement data to better separate useful acceleration information, thereby obtaining accelerometer data after eliminating harmful accelerometer velocity integrals.

[0047] In a specific embodiment, the accelerometer is used to measure the specific force information of the carrier in various directions, and the gyroscope is used to measure the angular velocity information of the carrier; in the carrier coordinate system b, the original measurement output of the accelerometer is expressed as f b , the raw measurement output of the gyroscope is expressed as Where i represents the inertial coordinate system and b represents the carrier coordinate system.

[0048] In a specific embodiment, for a gyroscope, its error compensation model is expressed as:

[0049]

[0050] in, is the gyro output after error compensation, is the gyroscope bias error vector, S g is the gyroscope scale factor matrix, ∈ g is the random error vector of the gyroscope.

[0051] In a specific embodiment, for the accelerometer, its error compensation model is:

[0052]

[0053] in, is the accelerometer output after error compensation, is the accelerometer bias error vector, S a is the accelerometer scale factor matrix, ∈ a is the random error vector of the accelerometer.

[0054] In a specific embodiment, the error-compensated gyroscope data Enter the attitude rate differential equation, which describes the relationship between the carrier attitude and time, and is expressed in the carrier coordinate system as:

[0055]

[0056] in, Represents the time derivative of the coordinate transformation matrix from the carrier coordinate system b to the navigation coordinate system n, is the coordinate transformation matrix from the carrier coordinate system b to the navigation coordinate system n, Is The antisymmetric matrix is ​​formed; by solving the differential equation, the attitude rate is calculated As the first pose information; at the same time, through the coordinate transformation matrix Conversion is performed between the carrier coordinate system and the navigation coordinate system to achieve unified processing of data in different coordinate systems.

[0057] The attitude rate differential equation is usually solved by numerical methods. For example, the fourth-order Runge-Kutta method can be used. First, based on the error-compensated gyroscope data at the current moment and the coordinate transformation matrix of the previous moment As the initial condition. Then, according to the calculation steps of the Runge-Kutta method, the coordinate transformation matrix and attitude rate of the next moment are calculated step by step. In each step of the calculation process, it is necessary to accurately calculate the The antisymmetric matrix The product of the coordinate transformation matrix and the attitude rate is updated. Through this numerical method, the attitude rate differential equation can be approximately solved at discrete time points, thereby obtaining a more accurate attitude rate as the first attitude information.

[0058] In one specific embodiment, the accelerometer data Combined with the attitude rate output of the attitude rate differential equation The data collected by the cold atom interferometer; first, the harmful accelerometer velocity integral is eliminated; the accelerometer data after eliminating the harmful accelerometer velocity integral is Then, the displacement angular rate ω is calculated according to the following relationship d :

[0059]

[0060] in, is the coordinate transformation matrix from the carrier coordinate system b to the navigation coordinate system n, g b is the representation of the Earth's gravitational acceleration in the carrier coordinate system, v b It is the expression of the carrier's velocity in the carrier coordinate system.

[0061] Calculate the displacement angular rate ω d When the coordinate transformation matrix from the carrier coordinate system to the navigation coordinate system is It plays a key role. It converts the acceleration and velocity information in the carrier coordinate system to the navigation coordinate system so that it can be compared with the earth's gravity acceleration g b and carrier speed v b Perform correct calculations. In actual calculations, it is necessary to ensure the accuracy of the coordinate transformation matrix, which depends on the accurate attitude information obtained by solving the previous attitude rate differential equation. For example, in aircraft navigation applications, the attitude of the carrier is constantly changing, and the coordinate transformation matrix also needs to be updated in real time to ensure the correctness of the displacement angular rate calculation. According to the above formula, first calculate the difference vector in the brackets, then perform a cross multiplication operation, and finally obtain the displacement angular rate. In this process, operations such as vector subtraction and cross multiplication are involved. It is necessary to pay attention to the rules and accuracy of vector operations to ensure the reliability of the calculation results.

[0062] In a specific embodiment, the displacement angular rate ω d As the input of the displacement angular rate differential equation; the displacement angular rate differential equation describes the relationship between the displacement angle and time, expressed as:

[0063]

[0064] By solving the differential equation, we can get the second pose information

[0065] In a specific embodiment, the fused pose information P is calculated by the following formula:

[0066]

[0067] In the formula, is the first pose information, is the second pose information, w1 and w2 are the weights corresponding to the first pose information and the second pose information respectively.

[0068] like Then the fused pose information P is:

[0069]

[0070] An inertial navigation system calibration system based on a cold atom interferometer comprises: a cold atom interferometer and a calibration system; the cold atom interferometer is composed of a vacuum unit, an electric control unit, an optical unit, and an autonomous traceability unit; the calibration system realizes online calibration of the inertial navigation system through relative measurement and calibration methods.

[0071] The vacuum unit includes cold atom preparation, state selection, interference and detection, and interacts with the optical unit including microwaves and lasers. It realizes atomic manipulation through the electronic control unit, and collects and processes the parameters required for inertial navigation parameter calibration.

[0072] Specifically, first, the 87Rb atoms will be cooled and trapped in the magneto-optical trap, and then they will be thrown upward to form an atomic fountain. When the atoms complete the horizontal state selection, they will pass through the upper and lower Raman light irradiation areas in the process of being thrown upward and falling. By controlling the timing, the atomic group will undergo a three-pulse timing to complete the splitting, reflection and combination of the atomic wave packets, realize three-pulse atomic interference, and finally obtain the interference fringes by detecting the final state of the atoms.

[0073] (1) Atom interferometer system: including atom trapping module, vacuum module, vibration suppression module, etc., used to generate and manipulate ultracold atomic clouds and generate atomic interference through laser pulses. These modules ensure that the atomic cloud is in an extremely low temperature and interference-free environment, thereby improving the stability and measurement accuracy of the interferometer. The main function of the atomic interferometer system is to sense the angular velocity and acceleration of rotation.

[0074] (2) Laser manipulation system: It consists of optical modules and circuit modules, responsible for generating and controlling the laser frequency and intensity used to manipulate atoms. The laser system requires high stability and accuracy to ensure accurate generation and measurement of atomic interference patterns. The laser manipulation system is used to generate lasers for cooling and manipulating atomic interference, and is one of the key technologies for achieving precise angular velocity and acceleration measurements.

[0075] (3) Independent traceability system

[0076] The online calibration system re-arranges the inertial navigation equations through the measurement of the earth's gravitational acceleration and the rotational angular velocity, and is used to send control instructions and display the user interface of the measurement results. It is responsible for coordinating the entire online calibration process, including parameter setting, data acquisition and analysis. The online calibration system realizes online calibration by controlling the parameter setting of the cold atom interferometer and the strapdown inertial navigation system. It also provides an interactive interface between the operator and the device, allowing users to easily set parameters, start measurements and view results.

[0077] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0078] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for calibrating an inertial navigation system based on a cold atom interferometer, characterized in that: include: Collect raw measurement data information through accelerometers and gyroscopes; Correct the errors in the original measurement data to obtain error-compensated gyroscope data and accelerometer data; The Earth's gravitational acceleration and the Earth's rotational angular velocity are collected through a cold atom interferometer, and the error-compensated gyroscope data and accelerometer data are calibrated; The calibrated gyroscope data enters the attitude rate differential equation, and the attitude rate is calculated as the first position information; And the coordinate conversion matrix is ​​used to convert between the carrier coordinate system and the navigation coordinate system; The accelerometer data is combined with the attitude rate output by the attitude rate differential equation and the data collected by the cold atom interferometer, and the displacement angular rate is calculated after eliminating the harmful accelerometer velocity integral processing; The displacement angular rate is used as the input of the displacement angular rate differential equation to obtain the second posture information; The first pose information is fused with the second pose information to obtain the pose output.

2. The method for calibrating an inertial navigation system based on a cold atom interferometer according to claim 1, characterized in that: The accelerometer is used to measure the specific force information of the carrier in all directions, and the gyroscope is used to measure the angular velocity information of the carrier; in the carrier coordinate system b, the original measurement output of the accelerometer is expressed as f b , the raw measurement output of the gyroscope is expressed as Where i represents the inertial coordinate system and b represents the carrier coordinate system.

3. The method for calibrating an inertial navigation system based on cold atom interferometer according to claim 1, characterized in that: For the gyroscope, its error compensation model is expressed as: in, is the gyro output after error compensation, is the gyroscope bias error vector, S g is the gyroscope scale factor matrix, ∈ g is the random error vector of the gyroscope.

4. The method for calibrating an inertial navigation system based on cold atom interferometer according to claim 1, characterized in that: For the accelerometer, the error compensation model is: in, is the accelerometer output after error compensation, is the accelerometer bias error vector, S a is the accelerometer scale factor matrix, ∈ a is the random error vector of the accelerometer.

5. The method for calibrating an inertial navigation system based on cold atom interferometer according to claim 3, characterized in that: Gyroscope data after error compensation Enter the attitude rate differential equation, which describes the relationship between the carrier attitude and time, and is expressed in the carrier coordinate system as: in, Represents the time derivative of the coordinate transformation matrix from the carrier coordinate system b to the navigation coordinate system n, is the coordinate transformation matrix from the carrier coordinate system b to the navigation coordinate system n, Is The antisymmetric matrix is ​​formed; by solving the differential equation, the attitude rate is calculated As the first pose information; at the same time, through the coordinate transformation matrix Conversion is performed between the carrier coordinate system and the navigation coordinate system to achieve unified processing of data in different coordinate systems.

6. The method for calibrating an inertial navigation system based on cold atom interferometer according to claim 4, characterized in that: Accelerometer data Combined with the attitude rate output of the attitude rate differential equation The data collected by the cold atom interferometer; first, the harmful accelerometer velocity integral is eliminated; the accelerometer data after eliminating the harmful accelerometer velocity integral is Then, the displacement angular rate ω is calculated according to the following relationship d : in, is the coordinate transformation matrix from the carrier coordinate system b to the navigation coordinate system n, g b is the representation of the Earth's gravitational acceleration in the carrier coordinate system, v b It is the expression of the carrier's velocity in the carrier coordinate system.

7. The method for calibrating an inertial navigation system based on cold atom interferometer according to claim 1, characterized in that: The displacement angular rate ω d As the input of the displacement angular rate differential equation; the displacement angular rate differential equation describes the relationship between the displacement angle and time, expressed as: By solving the differential equation, we can get the second pose information 8. The method for calibrating an inertial navigation system based on cold atom interferometer according to claim 1, characterized in that: The fused pose information P is calculated by the following formula: In the formula, is the first pose information, is the second pose information, w1 and w2 are the weights corresponding to the first pose information and the second pose information respectively.

9. An inertial navigation system calibration system based on cold atom interferometer, characterized in that: A method for calibrating an inertial navigation system based on a cold atom interferometer according to any one of claims 1 to 8, comprising: a cold atom interferometer and a calibration system; the cold atom interferometer is composed of a vacuum unit, an electronic control unit, an optical unit, and an autonomous traceability unit, and the calibration system realizes online calibration of the inertial navigation system through relative measurement and calibration methods.

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