Hybrid mode based hrg-ins collaborative calibration and rotation modulation method and system

Abstract

The application relates to a hybrid mode-based HRG-INS cooperative calibration and rotation modulation method and system, through the synergistic effect among hybrid mode operation, double-system cooperative calibration and three-axis rotation modulation, the navigation accuracy and reliability of the system in a complex environment are comprehensively improved; through hybrid mode data fusion, the advantages of full-angle mode and force balance mode output are complemented, and the dynamic adaptability and measurement robustness of the system are enhanced; relying on the double-inertial navigation cooperative calibration mechanism, the error parameters are estimated and compensated in real time by using the information mutual calibration between systems; combined with the three-axis rotation modulation technology, the residual error is periodically modulated, and the influence of inertial device errors such as zero offset, scale factor error and installation error is effectively modulated; the synergistic effect of the above-mentioned technologies realizes the synchronous improvement of the navigation accuracy and reliability, thereby substantially expanding the application range of the hemispherical resonator gyro inertial navigation system.

Description

Technical Field

[0001] This invention relates to the field of inertial navigation system technology, and in particular to a method and system for collaborative calibration and rotation modulation of a hemispherical resonator gyro inertial navigation system (HRG-INS) based on hybrid mode, which is suitable for high-precision and high-reliability inertial navigation systems. Background Technology

[0002] High-precision navigation systems are the core technological foundation of modern transportation systems. Among various navigation methods, inertial navigation, with its unique advantages such as complete autonomy, strong anti-interference capabilities, and wide applicability, has become an indispensable core supporting technology in land, sea, air, and space fields, and is a strategic competitive high ground and cutting-edge research and development direction at the forefront of global science and technology.

[0003] Inertial navigation systems (INS) have long been developing towards smaller size, lower power consumption, lower cost, and higher performance. However, traditional mechanical and optical gyroscopes are limited by their physical mechanisms, resulting in significant constraints on size, cost, and accuracy, making it difficult to simultaneously meet these requirements and limiting their application in advanced equipment such as autonomous underwater vehicles. In contrast, hemispherical resonant gyroscopes (HRGs) exhibit significant advantages: their theoretical accuracy is not directly related to the size of the sensing element, and they possess multiple advantages such as high precision, high reliability, long lifespan, low power consumption, strong radiation resistance, simple structure, and low cost. Furthermore, they can maintain operation for tens of minutes after a power outage, thus being internationally recognized as a disruptive gyroscope technology and becoming a research hotspot in the field of inertial technology both domestically and internationally. Although the HRG-INS hemispherical resonant gyroscope inertial navigation system has been successfully applied in satellite attitude determination and navigation, it still struggles to meet high-precision requirements in aviation, automotive, and underwater environments.

[0004] Currently, hemispherical resonator gyroscopes mainly include two operating modes: force balance mode (closed-loop control) and full-angle mode (open-loop control). Force balance mode boasts extremely high measurement accuracy and very low noise, but its bandwidth and range are limited by the control loop and feedback force, making further improvements difficult. Full-angle mode, on the other hand, theoretically possesses unlimited bandwidth and range, but due to manufacturing limitations, it is susceptible to the effects of uneven damping and stiffness of the resonator, leading to angle-related errors and low-speed detection threshold issues. Therefore, the two existing modes each have their advantages and disadvantages, possessing complementary potential.

[0005] In maintaining the accuracy of inertial navigation systems (INS), calibration technology, which estimates error parameters by establishing input-output models of inertial devices, is crucial for achieving high-precision navigation. However, due to environmental changes and device aging, system error parameters drift over time, leading to accuracy degradation. Traditional solutions include periodic factory calibration, but this causes equipment downtime. Another approach is self-calibration using a transducer and external information (such as GNSS), which can meet some field requirements but still relies on a stationary carrier or a reliable external reference, limiting its applicability in environments lacking stable reference information (such as underwater or GNSS-denied zones). Therefore, existing field calibration techniques are difficult to implement without external reference support, limiting their effectiveness in practical applications.

[0006] To address the error divergence problem of inertial navigation systems (INS) during long-endurance missions, rotation modulation technology is widely used. This technique modulates the constant error of inertial devices by periodically rotating the inertial measurement unit (IMU), thereby suppressing their cumulative effects. From the perspective of the body coordinate system, the device drift remains unchanged; however, in the navigation coordinate system, its effects alternate between positive and negative, which can cancel each other out to some extent. Single-axis rotating INS cannot modulate device errors along the rotation axis, and dual-axis rotating INS has some coupling error terms that are difficult to eliminate. Therefore, neither of these rotation methods can completely modulate the device errors.

[0007] Based on the above analysis, if we can fuse the outputs of the two modes of the hemispherical resonant gyroscope, solve the problem of external field self-calibration of the inertial navigation system in the absence of reference information, and overcome the limitations of single-axis and dual-axis rotating inertial navigation systems in error modulation, and achieve modulation of the constant error of all inertial devices, then we can comprehensively improve the navigation accuracy and reliability of the inertial navigation system in complex environments, and further expand the applicable scope of the hemispherical resonant gyroscope inertial navigation system. Summary of the Invention

[0008] This invention aims to address the aforementioned problems in the prior art by providing a hybrid-mode HRG-INS collaborative calibration and rotation modulation method and system. The core of this invention lies in a complete method and hardware framework. Through the synergistic effect of hybrid-mode operation, dual-system collaborative calibration, and three-axis rotation modulation, it systematically overcomes the limitations of single technologies, comprehensively improving the navigation accuracy and reliability of the system in complex environments.

[0009] To solve the technical problem, the specific technical solution adopted by this invention is as follows:

[0010] The HRG-INS collaborative calibration and rotation modulation method based on hybrid modes consists of the following steps:

[0011] S1 system construction; the specific process is as follows:

[0012] The redundant dual inertial navigation system S1-1 is constructed as follows: Two identical hemispherical resonant gyroscope inertial navigation systems HRG-INS are installed on the carrier. The main inertial navigation unit H is defined as the normally operating inertial navigation system, and its carrier coordinate system b1 is defined as right-front-up. The redundant inertial navigation unit L is the inertial navigation system to be calibrated, and its carrier coordinate system b2 is defined as above.

[0013] S1-2 Inertial Navigation System H and Inertial Navigation System L are both navigation systems based on a three-axis rotating inertial navigation system, including a base, an outer ring rotating frame, a middle ring rotating frame, an inner ring rotating frame and an inertial measurement unit. The inertial measurement unit is installed on the inner ring rotating frame of the three-axis turntable. Each inertial measurement unit includes three main gyroscopes and three main accelerometers.

[0014] The geometrical correspondence between the axes of the S1-3 three-axis turntable and the axes of the x, y, and z axes of the hemispherical resonant gyroscope inertial navigation system is as follows: When the three-axis turntable is in the zero position, the axis parallel to the axis of the turntable's central axis is the y-axis of the inertial navigation system; the axis parallel to the axis of the turntable's inner axis is the z-axis of the inertial navigation system. At this time, the axis of the turntable's outer axis is also parallel to the z-axis of the inertial navigation system; the x-axis, which is orthogonal to the y-axis and z-axis, can be obtained from the right-hand coordinate system.

[0015] Simultaneously, determine the navigation coordinate system, vehicle coordinate system, geocentric inertial coordinate system, and Earth coordinate system: select "East-North-Sky" ( The geographic coordinate system is used as the navigation coordinate system, denoted as the n system; the right-front-up coordinate system is selected as the carrier coordinate system, denoted as the b system; the geocentric inertial coordinate system is denoted as the i system; and the Earth coordinate system is denoted as the e system.

[0016] S2 hybrid mode data fusion processing; the specific process is as follows:

[0017] S2-1 powers on the inertial navigation system. After each hemispherical resonator gyroscope has started oscillating, the force balance control loop is activated. The output of the PI controller in the hemispherical resonator gyroscope force balance loop is taken as the original force balance output of the gyroscope. After calibration with the initial calibration parameters, it is used as the gyroscope force balance output. The standing wave rate of the hemispherical resonator gyroscope is taken as the original full-angle output of the gyroscope. After calibration with the initial calibration parameters, it is used as the full-angle output of the gyroscope. The initial calibration parameters are the device's factory calibration results or the results of the previous calibration.

[0018] To obtain angular rate information with both high accuracy and wide bandwidth, S2-2 establishes a data fusion model. One of the core aspects of this model is compensating for the time delay error between the gyro force balance output and the full-angle output. In practical systems, it is impossible to directly obtain the angular increment output under force balance mode at time t after compensating for the time delay error. The true value is obtained by compensating for it using a first-order approximation model. By compensating for and fusing errors such as time delay, the final ideal output estimate of the gyroscope (i.e., the output of the data fusion mode) is obtained, and its model is as follows:

[0019] (1)

[0020] In equation (1), This represents an estimate of the ideal output of the gyroscope (i.e., the gyroscope output in the data fusion mode). This represents the actual angle increment output in full-angle mode of the gyroscope, where They represent Actual angle increment output of the axial gyroscope in full-angle mode; This represents the actual angular increment output (i.e., force balance output) in gyroscope force balance mode, where They represent Actual angular increment output in axial gyroscope force balance mode; This represents the time delay error between the gyroscope force-balanced output and the full-angle output, where They represent The time delay error between the two modes of the axis gyroscope, where the subscript k indicates time k. This represents the sampling interval of the actual inertial navigation system; ".*" is the .* operator in Matlab, which indicates element-wise multiplication.

[0021] S2-3 will output the data fusion mode gyroscope obtained from equation (1). As a multi-mode data fusion output for practical use, it replaces the original gyroscope full-angle output or force balance output in subsequent navigation calculations.

[0022] S3 dual inertial navigation system collaborative online calibration; the specific process is as follows:

[0023] S3-1 Constructing an Error Model for a Dual Inertial Navigation System

[0024] Due to the high-precision navigation requirements for long-duration shipboard operations, the scaling factor error (≤0.5ppm) and installation error (≤1″) of a normally functioning inertial navigation system (INS) H are extremely small compared to the INS L to be calibrated. These two types of errors can be ignored, and only the constant zero bias and measurement noise of the inertial devices are considered as the benchmark for subsequent calibration. For the INS L to be calibrated (redundant INS), the scaling factor error, installation error, constant zero bias, and measurement noise of its gyroscopes and accelerometers must be fully incorporated to ensure that the error model can cover the key error terms affecting navigation accuracy. The specific construction method of the dual INS system error model, including the definition of error terms and the derivation of the model form, can be found in Chinese Patent "A Method for Online Cooperative Calibration of Dual INS Systems in the Field: ZL202310230521.5".

[0025] S3-2 Establishing a Joint State Observation and Kalman Filter Model

[0026] Using the hybrid mode fusion data (combining high precision and large bandwidth) of the main inertial navigation system H as a benchmark, and leveraging the characteristic of measuring the motion of the same carrier using two inertial navigation systems, a joint error equation for the system is constructed. This equation encompasses the propagation relationships of attitude error, velocity error, and position error. Based on the joint error equation, a joint state vector is defined. In addition to containing the attitude, velocity, and position errors of the two inertial navigation systems, the vector also incorporates the estimated error parameters of the inertial navigation system L to be calibrated (gyroscope scale factor error, gyroscope installation error, accelerometer scale factor error, and accelerometer installation error), thereby determining the joint state equation.

[0027] Using the relative velocity and relative position of the two inertial navigation systems as the core observations, constraint relationships are constructed using the parameters of the external arm (obtained during system installation with an accuracy of ±1mm). Simultaneously, the height information of the main inertial navigation system H is supplemented as an auxiliary observation to construct the state-constrained observation equations. Based on the joint state equations and the state-constrained observation equations, a joint state Kalman filter is built to achieve real-time estimation of the error parameters of the inertial navigation system L to be calibrated. The construction logic of the joint state equations and observation equations, as well as the initialization and iterative solution method of the Kalman filter, can be found in Chinese patent "A Method for Online Collaborative Calibration of a Dual Inertial Navigation System in the External Field: ZL202310230521.5".

[0028] S3-3 Performs dual inertial navigation joint rotation excitation

[0029] To fully incentivize the error parameters of the inertial navigation system (INS) L to be calibrated, and to transform the originally unobservable error terms into identifiable quantities, the three-axis turntable is controlled to drive the dual INS measurement units to perform a joint rotation action: the main INS unit H adopts a dual-axis multi-sequence rotation to maintain the navigation state and provide a stable reference. During the rotation process, a preset time is required to stop after each rotation sequence is completed (to ensure data stability); the redundant INS unit L adopts a three-axis multi-sequence rotation, and maximizes the excitation of the influence of its scaling factor error and installation error through multi-axis alternating rotation.

[0030] During the rotation, angular and acceleration increment data of the two inertial navigation systems are synchronously collected at a preset sampling frequency (200Hz). After preliminary error compensation processing, the data is transmitted to the data processing module to provide data support for subsequent error parameter estimation. The design of the order of the dual inertial navigation joint rotation and the method for setting the rotation angular velocity and rotation stop time can be found in Chinese patent "A method for online calibration of dual inertial navigation system in the field: ZL202310230521.5".

[0031] S3-4 Error Parameter Estimation and Calibration Applications

[0032] In the data processing module, the joint state Kalman filter is started, and the joint state vector is iteratively estimated at a preset update frequency (100Hz). The convergence of the error parameters to be estimated for the redundant inertial navigation unit L is monitored in real time: when the parameter estimate changes less than the preset threshold (scale factor error change ≤ 0.1ppm, installation error change ≤ 0.3″) after a preset number of consecutive updates (e.g., 500 times), the parameter convergence is determined, and the final calibration result is output.

[0033] The converged error parameters are stored in the storage module and sent to the error pre-compensation submodule of the information acquisition module in real time to perform real-time error compensation on the measurement data subsequently acquired by the redundant inertial navigation unit L. After compensation, the accuracy of the inertial devices of L is consistent with that of the main inertial navigation unit H (HRG zero bias stability ≤ 0.003° / h, accelerometer zero bias ≤ 20μg), thus completing the collaborative online calibration of the redundant inertial navigation unit L.

[0034] S4 performs three-axis rotation modulation; the specific process is as follows:

[0035] S4-1 The sixteen-order rotation strategy for the geocentric inertial frame is designed as follows:

[0036] Using the geocentric inertial frame (i-frame) as a reference, define the Z-axis of the i-frame. i The axis is the Earth's rotation axis (north-oriented), X i With the axis pointing to the vernal equinox, a uniform rotational angular velocity (e.g., 9° / s) is set, and a sixteen-sequence rotation process is designed: by rotating alternately in both directions around the i-system Zi and Xi axes (each sequence rotates 180°), the error of the inertial device is made to exhibit periodic changes in space, laying the foundation for subsequent error cancellation.

[0037] The specific arrangement logic of the sixteen sequences (such as the alternation rule of forward and reverse rotation) and the selection criteria of the rotation axis system can be found in Chinese patent "A three-axis rotation modulation method for a strapdown inertial navigation system based on a geocentric inertial frame, ZL202110410482.8"; at the same time, the sixteen sequences can be grouped into groups of four, and the order between groups can be arbitrarily interchanged without affecting the error modulation effect, thus improving the flexibility of the method application.

[0038] S4-2 Calculation of the projection of Earth's rotation angular velocity onto the navigation system and isolation compensation

[0039] Based on the navigation calculation results of the main inertial navigation unit H, the current latitude and longitude information of the carrier is obtained. Using the transformation matrix from the geocentric inertial frame to the Earth system and from the Earth system to the navigation coordinate system (n system, East-North-Sky), the projection components of the Earth's rotation angular velocity in the navigation coordinate system are calculated (the east component is 0, and the north and sky components vary with latitude).

[0040] To eliminate the coupling effect between the Earth's rotation angular velocity and inertial device errors (and prevent this coupling from causing long-term divergence in navigation errors), an isolation compensation term is introduced into the rotation angular velocity in the navigation coordinate system. This term makes the rotation angular velocity in the navigation coordinate system equal to the equivalent rotation angular velocity in the geocentric inertial frame minus the navigation frame projection component of the Earth's rotation angular velocity. This ensures that during rotation modulation, the integral of the inertial device error term over one rotation cycle approaches zero, effectively isolating the influence of the Earth's rotation. The calculation method for the Earth's rotation angular velocity projection, the principle of isolation compensation, and the derivation of the formula can be found in Chinese Patent "A Three-Axis Rotation Modulation Method for a Strapdown Inertial Navigation System Based on a Geocentric Inertial Frame, ZL202110410482.8".

[0041] S4-3 Performs sixteen-order three-axis rotations under the navigation system

[0042] The sixteen sequential rotational angular velocities in the geocentric inertial frame are converted into rotational angular velocities in the navigation coordinate system by combining the isolation compensation results of S4-2. The rotation time for each sequence is determined by the rotation angle and the magnitude of the angular velocity (e.g., the time is approximately 20 seconds for a 180° rotation). The conversion logic of the rotational angular velocities in the navigation coordinate system can be found in Chinese patent "A Three-Axis Rotation Modulation Method for Strapdown Inertial Navigation System Based on Geocentric Inertial Frame, ZL202110410482.8".

[0043] The drive control submodule of the rotation modulation execution module receives the rotation parameters under the navigation system and drives the three-axis rotation frame to drive the dual inertial navigation measurement units to perform rotation actions in sequence.

[0044] The present invention also proposes a hybrid mode HRG-INS cooperative calibration and rotation modulation redundant dual inertial navigation system, including an information acquisition module, a rotation modulation execution module, a data processing module, and a supporting storage module, which are connected in sequence.

[0045] The information acquisition module includes a dual inertial navigation measurement unit, a data acquisition submodule, and an error pre-compensation submodule connected in sequence. The data acquisition submodule is used to synchronously acquire the raw data of the angular increment and acceleration increment of the main inertial navigation unit H and the redundant inertial navigation unit L at a preset sampling frequency. The error pre-compensation submodule is used to perform preliminary error compensation on the acquired raw measurement data using the initial calibration parameters in the storage module, and transmit the compensated inertial navigation measurement data to the data processing module.

[0046] The data processing module runs on the navigation control panel, and the output information of the information acquisition module and the calculation data of the data processing module are stored in the storage module.

[0047] The dual inertial navigation measurement unit (INS) provides raw inertial measurement data to support the hybrid-mode operation of the collaborative calibration and rotation modulation system. It serves as the sensing core for subsequent data fusion, collaborative calibration, and rotation modulation. It includes a main INS unit H and a redundant INS unit L; the main INS unit H contains a three-axis hemispherical resonant gyroscope G that supports hybrid modes (force balance / full-angle mode). H and triaxial accelerometer A H The redundant inertial navigation unit L contains a triaxial hemispherical resonant gyroscope G that supports hybrid modes. L and triaxial accelerometer A L .

[0048] The rotation modulation execution module is fixedly connected to the inertial measurement component of the dual inertial navigation measurement unit. It includes a three-axis rotation frame submodule and a drive control submodule, which are used to perform 16 sequential periodic rotation actions to achieve spatial modulation of the inertial navigation constant error.

[0049] The data processing module includes a hybrid mode fusion submodule, a dual inertial navigation system collaborative calibration submodule, and a rotation modulation control submodule. The hybrid mode fusion submodule is used to switch and superimpose gyroscope dual-mode data. The dual inertial navigation system collaborative calibration submodule uses the output difference of the two systems to construct observations and estimate and calculate the error parameters of the redundant inertial navigation unit L in real time. The rotation modulation control submodule is used to issue action commands to the rotation modulation execution module.

[0050] The angular increments and acceleration increments of the main inertial navigation unit H and the redundant inertial navigation unit L are synchronously acquired through the data acquisition submodule. After error compensation by the error pre-compensation submodule, the compensated inertial navigation measurement data is output. This data is transmitted to the data processing module of the navigation control board for calculation and outputs the attitude, velocity and position information of the carrier.

[0051] The present invention has the following beneficial effects:

[0052] By using a hybrid mode data fusion method, the high measurement accuracy of the hemispherical resonant gyroscope force balance mode and the large bandwidth characteristics of the full-angle mode are effectively combined, thereby improving the dynamic response capability and angular rate measurement accuracy of the inertial measurement unit from the source.

[0053] The dual-inertial navigation system collaborative online calibration technology is adopted. Using the main inertial navigation system that has been precisely calibrated and rotated as a reference, the full parameters of the redundant inertial navigation system are estimated online through relative motion constraints. This breaks through the dependence of traditional calibration methods on external reference information and realizes a completely autonomous calibration capability.

[0054] By combining three-axis rotation modulation with outer-axis heading isolation control, the constant error of the inertial devices in the three axes is effectively modulated, overcoming the problem of incomplete error modulation in single-axis and dual-axis rotation modulation, and significantly suppressing the divergence of navigation error.

[0055] By organically combining hybrid mode operation, dual-system collaborative calibration, and three-axis rotation modulation, a complete autonomous accuracy maintenance system has been constructed, which has the technical advantages of full autonomy, all working conditions, and high reliability. It is particularly suitable for long-endurance high-precision navigation missions in GNSS-denied environments such as underwater and underground. Attached Figure Description

[0056] Figure 1 System configuration;

[0057] Figure 2 A redundant dual inertial navigation system;

[0058] Figure 3 System structure composition diagram;

[0059] Figure 4 Navigation speed error;

[0060] Figure 5 Navigation position error. Detailed Implementation

[0061] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0062] To make the technical methods and advantages of this application clearer, the present invention will be further described below with reference to the accompanying drawings. The specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0063] 1) System Construction: Two identical hemispherical resonant gyroscope inertial navigation systems, defined as inertial navigation system H and inertial navigation system L, are installed on the carrier. Inertial navigation system H is the primary inertial navigation system, and inertial navigation system L is the system to be calibrated. Both systems are based on a three-axis rotation mechanism configuration, including a base, a rotating frame, and an inertial measurement unit. The navigation coordinate system, carrier coordinate system, and other relevant coordinate systems are determined.

[0064] 2) Hybrid Mode Data Fusion Processing: Data fusion is performed on the force balance mode and full-angle mode outputs of the hemispherical resonator gyroscope. When the external angular velocity is small, the system operates in force balance mode, providing high-precision output; when the external angular velocity is large, the force balance mode may lose information, in which case the full-angle mode output is used for compensation, and the fused hybrid mode output is obtained, which balances accuracy and bandwidth.

[0065] 3) Dual-inertial navigation collaborative online calibration: By utilizing the output differences of the two inertial navigation systems, a joint state equation and observation equation are constructed. The error parameters of the inertial navigation L (such as scaling factor error, installation error and zero bias) are estimated in real time through a filtering algorithm, so as to achieve online calibration without external reference.

[0066] 4) Implement three-axis rotation modulation: By using a three-axis rotation scheme based on a geocentric inertial frame, the two inertial navigation systems perform periodic rotational motions, modulating the constant error of the inertial devices. The rotation scheme ensures that the error effects alternate between positive and negative in the navigation coordinate system, thereby offsetting the cumulative effect.

[0067] To verify the effectiveness of the method of this invention, navigation simulations were conducted and compared under hybrid mode, dual inertial navigation system collaborative calibration, and three-axis rotation modulation methods. The simulation conditions were as follows: considering only non-random errors of the components, the gyroscope constant drift error, scale factor error, and installation error were 0.01° / h, 1ppm, and 2″, respectively; the accelerometer constant drift error, scale factor error, installation error, and quadratic term error were 10μg, 5ppm, 5″, and 5μg / g, respectively. 2 No initial alignment error; initial longitude, latitude, and altitude were 112.9916°, 28.2202°, ​​and 0m, respectively; initial northeast-southeast celestial velocity was 0m / s. The simulation duration was 10 hours, alignment time was 4 hours, and navigation time was 6 hours. The simulation results are as follows: Figure 3 Figure 4 As shown. Figure 3 For navigation speed error, Figure 4 This represents the navigation position error. It can be seen that... Figure 3 The velocity error oscillation amplitude remained stable at around 2 m / s. Figure 4 The position error oscillation amplitude remained stable at around 2 nautical miles.

[0068] Therefore, this invention provides a comprehensive solution for the collaborative calibration and three-axis rotation modulation method of HRG-INS based on hybrid mode. It establishes a complete hardware and methodological framework, and through the synergistic effect of hybrid mode operation, dual-system collaborative calibration, and three-axis rotation modulation, systematically overcomes the limitations of single technologies, comprehensively improving the navigation accuracy and reliability of the system in complex environments. Hybrid mode data fusion achieves complementary advantages between full-angle mode and force balance mode output, enhancing the system's dynamic adaptability and measurement robustness. Relying on the dual-inertial navigation collaborative calibration mechanism, it utilizes inter-system information mutual calibration to estimate and compensate error parameters in real time. Combined with three-axis rotation modulation technology, it periodically modulates residual errors, effectively modulating the influence of inertial device errors such as zero bias, scale factor error, and installation error. The synergistic effect of these technologies achieves simultaneous improvement in navigation accuracy and reliability, thereby substantially expanding the application scope of hemispherical resonant gyroscope inertial navigation systems.

Claims

1. A hybrid-mode HRG-INS collaborative calibration and rotation modulation method, characterized in that, This method consists of the following steps: S1 system construction; the specific process is as follows: The redundant dual inertial navigation system S1-1 is constructed as follows: Two identical hemispherical resonant gyroscope inertial navigation systems HRG-INS are installed on the carrier. The main inertial navigation unit H is defined as the normally operating inertial navigation system, and its carrier coordinate system b1 is defined as right-front-up. The redundant inertial navigation unit L is the inertial navigation system to be calibrated, and its carrier coordinate system b2 is defined as above. S1-2 Inertial Navigation System H and Inertial Navigation System L are both navigation systems based on a three-axis rotating inertial navigation system, including a base, an outer ring rotating frame, a middle ring rotating frame, an inner ring rotating frame and an inertial measurement unit. The inertial measurement unit is installed on the inner ring rotating frame of the three-axis turntable. Each inertial measurement unit includes three main gyroscopes and three main accelerometers. The geometrical correspondence between the axes of the S1-3 three-axis turntable and the axes of the x, y, and z axes of the hemispherical resonant gyroscope inertial navigation system is as follows: When the three-axis turntable is in the zero position, the axis parallel to the axis of the turntable's central axis is the y-axis of the inertial navigation system; the axis parallel to the axis of the turntable's inner axis is the z-axis of the inertial navigation system. At this time, the axis of the turntable's outer axis is also parallel to the z-axis of the inertial navigation system; the x-axis, which is orthogonal to the y-axis and z-axis, can be obtained from the right-hand coordinate system. At the same time, the navigation coordinate system, the carrier coordinate system, the geocentric inertial coordinate system, and the Earth coordinate system are determined: the "East-North-Sky" geographic coordinate system is selected as the navigation coordinate system, denoted as the n system; We select the "right-front-up" coordinate system as the carrier coordinate system, denoted as system b; the geocentric inertial coordinate system is denoted as system i; and the Earth coordinate system is denoted as system e. S2 hybrid mode data fusion processing; the specific process is as follows: S2-1 Power on the inertial navigation system. After each hemispherical resonant gyroscope has started oscillating, turn on the force balance control loop. Take the output of the PI controller of the hemispherical resonant gyroscope force balance loop as the original force balance output of the gyroscope. After calibration with the initial calibration parameters, take it as the force balance output of the gyroscope. Take the standing wave angular rate of the hemispherical resonant gyroscope as the original full angle output of the gyroscope. After calibration with the initial calibration parameters, take it as the full angle output of the gyroscope. S2-2 establishes a data fusion model to obtain angular rate information with both high accuracy and wide bandwidth; one of the core aspects of this model is to compensate for the time delay error between the gyro force balance output and the full-angle output. In practical systems, it is impossible to directly obtain the angular increment output under force balance mode at time t after compensating for the time delay error. The true value is obtained by compensating for it using a first-order approximation model. By compensating for and fusing errors such as time delay, the final ideal output estimate of the gyroscope is obtained, and its model is as follows: ，(1) In equation (1), This represents an estimate of the ideal output of the gyroscope; This represents the actual angle increment output in full-angle mode of the gyroscope, where They represent Actual angle increment output of the axial gyroscope in full-angle mode; This represents the actual angular increment output in gyro force balance mode, where They represent Actual angular increment output in axial gyroscope force balance mode; This represents the time delay error between the gyroscope force-balanced output and the full-angle output, where They represent The time delay error between the two modes of the axis gyroscope, where the subscript k indicates time k. This represents the sampling interval of the actual inertial navigation system; ".*" is the .* operator in Matlab, which indicates element-wise multiplication; S2-3 will output the data fusion mode gyroscope obtained from equation (1). As a multi-mode data fusion output for practical use, it replaces the original gyroscope full-angle output or force balance output to participate in subsequent navigation calculations; S3 dual inertial navigation system collaborative online calibration; the specific process is as follows: S3-1 Constructing an Error Model for a Dual Inertial Navigation System Only the constant zero bias and measurement noise of the inertial devices are considered as the reference for subsequent calibration; for the inertial navigation system L to be calibrated, the scaling factor error, installation error, constant zero bias and measurement noise of its gyroscope and accelerometer must be fully included to ensure that the error model can cover the key error terms that affect navigation accuracy. S3-2 Establishing a Joint State Observation and Kalman Filter Model Based on the hybrid mode fusion data of the main inertial navigation system H, and taking advantage of the characteristics of the two inertial navigation systems measuring the motion of the same carrier, a joint error equation of the system is constructed. The equation covers the propagation relationship of attitude error, velocity error, and position error. Based on the joint error equation, a joint state vector is defined. In addition to the attitude, velocity, and position errors of the two inertial navigation systems, the vector also includes the error parameters to be estimated of the inertial navigation system L to be calibrated, thereby determining the joint state equation. Using the relative velocity and relative position of the two inertial navigation systems as the core observations, constraint relationships are constructed using the parameters of the outer arm, and the height information of the main inertial navigation system H is supplemented as an auxiliary observation to construct the state constraint observation equation. Based on the joint state equation and the state constraint observation equation, a joint state Kalman filter is built to realize the real-time estimation of the error parameters of the inertial navigation system L to be calibrated. S3-3 Performs dual inertial navigation joint rotation excitation To fully incentivize the error parameters to be estimated in the inertial navigation system L to be calibrated, and to transform the originally unobservable error terms into identifiable quantities, the three-axis turntable is controlled to drive the dual inertial navigation measurement units to perform joint rotation actions: the main inertial navigation unit H adopts dual-axis multi-sequence rotation to maintain the navigation state and provide a stable reference. During the rotation process, a preset time is required to stop after each sequence of rotation is completed. The redundant inertial navigation unit L adopts a three-axis multi-sequence rotation method, which maximizes the excitation of the influence of its scaling factor error and installation error through multi-axis alternating rotation; During the transposition, the angular increment and acceleration increment data of the two inertial navigation systems are collected synchronously at the preset sampling frequency. After preliminary error compensation processing, the data is transmitted to the data processing module to provide data support for subsequent error parameter estimation. S3-4 Error Parameter Estimation and Calibration Applications In the data processing module, the joint state Kalman filter is started, and the joint state vector is iteratively estimated at a preset update frequency. The convergence of the error parameters to be estimated in the redundant inertial navigation unit L is monitored in real time: when the change in the parameter estimate is less than the preset threshold after a preset number of consecutive updates, the parameter convergence is determined, and the final calibration result is output. The converged error parameters are stored in the storage module and sent to the error pre-compensation submodule of the information acquisition module in real time to perform real-time error compensation on the measurement data subsequently acquired by the redundant inertial navigation unit L. After compensation, the accuracy of the inertial devices of L is consistent with that of the main inertial navigation unit H, thus completing the collaborative online calibration of the redundant inertial navigation unit L. S4 performs three-axis rotation modulation; the specific process is as follows: S4-1 The sixteen-order rotation strategy for the geocentric inertial frame is designed as follows: Using the geocentric inertial frame as a reference, define the Z-axis of the i-frame. i The axis is the Earth's rotation axis, X i With the axis pointing to the vernal equinox, a uniform rotational angular velocity is set, and a sixteen-step rotation process is designed: by rotating alternately in both directions around the i-system Zi and Xi axes, the error of the inertial device is made to exhibit periodic changes in space, laying the foundation for subsequent error cancellation. S4-2 Calculation of the projection of Earth's rotation angular velocity onto the navigation system and isolation compensation Based on the navigation calculation results of the main inertial navigation unit H, the current latitude and longitude information of the carrier is obtained. Using the transformation matrix from the geocentric inertial frame to the Earth system and from the Earth system to the navigation coordinate system, the projection component of the Earth's rotation angular velocity in the navigation coordinate system is calculated. To eliminate the coupling effect between the Earth's rotation angular velocity and the error of the inertial device, an isolation compensation term is introduced into the rotation angular velocity in the navigation coordinate system: the rotation angular velocity in the navigation coordinate system is equal to the equivalent rotation angular velocity in the geocentric inertial frame minus the navigation frame projection component of the Earth's rotation angular velocity, ensuring that the integral of the inertial device error term over one rotation cycle approaches zero during the rotation modulation process, thus achieving effective isolation of the Earth's rotation effect; S4-3 Performs sixteen-order three-axis rotations under the navigation system The sixteen sequential rotational angular velocities in the geocentric inertial frame are converted into rotational angular velocities in the navigation coordinate system by combining the isolation compensation results of S4-2. The rotation time of each sequence is determined by the rotation angle and the magnitude of the angular velocity. The drive control submodule of the rotation modulation execution module receives the rotation parameters under the navigation system and drives the three-axis rotation frame to drive the dual inertial navigation measurement units to perform rotation actions in sequence.

2. The HRG-INS cooperative calibration and rotation modulation method based on hybrid mode according to claim 1, characterized in that: In S2-1, the initial calibration parameters are the device's factory calibration results or the previous calibration results.

3. The HRG-INS cooperative calibration and rotation modulation method based on hybrid mode according to claim 1, characterized in that: In S3-3, the preset sampling frequency is 200Hz.

4. The HRG-INS cooperative calibration and rotation modulation method based on hybrid mode according to claim 1, characterized in that: In S3-4, the default update frequency is 100Hz.

5. The HRG-INS cooperative calibration and rotation modulation method based on hybrid mode according to claim 1, characterized in that: In S3-4, the preset number of consecutive times is 500.

6. The HRG-INS cooperative calibration and rotation modulation method based on hybrid mode according to claim 1, characterized in that: In S3-4, the preset thresholds are as follows: scale factor error change ≤ 0.1ppm, installation error change ≤ 0.3″.

7. The HRG-INS cooperative calibration and rotation modulation method based on hybrid mode according to claim 1, characterized in that: In S4-1, the rotational angular velocity is 9° / s, and the sixteen-step rotation process involves alternating forward and reverse rotations around the i-system Zi and Xi axes, with each step rotating 180°.

8. The HRG-INS cooperative calibration and rotation modulation method based on hybrid mode according to claim 1, characterized in that: In S4-1, the sixteen-order rotation can be grouped into groups of four, and the order between groups can be arbitrarily interchanged without affecting the error modulation effect.

9. A hybrid-mode HRG-INS cooperative calibration and rotational modulation redundant dual inertial navigation system, characterized in that: It includes an information acquisition module, a rotation modulation execution module, a data processing module, and a supporting storage module; The information acquisition module includes a dual inertial navigation measurement unit, a data acquisition submodule, and an error pre-compensation submodule connected in sequence. The data acquisition submodule is used to synchronously acquire the raw data of the angular increment and acceleration increment of the main inertial navigation unit H and the redundant inertial navigation unit L at a preset sampling frequency. The error pre-compensation submodule is used to perform preliminary error compensation on the acquired raw measurement data using the initial calibration parameters in the storage module, and transmit the compensated inertial navigation measurement data to the data processing module. The data processing module runs on the navigation control panel, and the output information of the information acquisition module and the calculation data of the data processing module are all stored in the storage module. The dual inertial navigation measurement unit is used to provide raw inertial measurement data to support the hybrid mode operation of the cooperative calibration and rotation modulation system. It is the sensing core for subsequent data fusion, cooperative calibration and rotation modulation: it includes a main inertial navigation unit H and a redundant inertial navigation unit L. The main inertial navigation unit H includes a three-axis hemispherical resonant gyroscope G that supports hybrid modes. H and triaxial accelerometer A H The redundant inertial navigation unit L contains a triaxial hemispherical resonant gyroscope G that supports hybrid modes. L and triaxial accelerometer A L ; The rotation modulation execution module is fixedly connected to the inertial measurement component of the dual inertial navigation measurement unit. It includes a three-axis rotation frame submodule and a drive control submodule, which are used to execute 16 sequential periodic rotation actions to achieve spatial modulation of the inertial navigation constant error. The data processing module includes a hybrid mode fusion submodule, a dual inertial navigation system collaborative calibration submodule, and a rotation modulation control submodule. The hybrid mode fusion submodule is used to switch and superimpose gyroscope dual-mode data. The dual inertial navigation system collaborative calibration submodule uses the output difference of the two systems to construct observations and estimate and calculate the error parameters of the redundant inertial navigation unit L in real time. The rotation modulation control submodule is used to issue action commands to the rotation modulation execution module. The angular increments and acceleration increments of the main inertial navigation unit H and the redundant inertial navigation unit L are synchronously acquired through the data acquisition submodule. After error compensation by the error pre-compensation submodule, the compensated inertial navigation measurement data is output. This data is transmitted to the data processing module of the navigation control board for calculation and outputs the attitude, velocity and position information of the carrier.

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