A method for on-the-go alignment of a hemispherical resonant gyro strapdown inertial navigation system assisted by a micromechanical gyro and a Doppler odometer

Abstract

The present invention provides a method for aligning a hemispherical resonant gyro strapdown inertial navigation system assisted by a micromechanical gyroscope and a Doppler odometer, and belongs to a signal processing method in the field of automation technology. The present invention firstly takes into account the characteristics that the carrier angular velocity is large during the bow movement of the ship, and the carrier angular velocity exceeds the measurement range of the force feedback hemispherical resonant gyroscope, and designs an angular velocity acquisition algorithm using a micromechanical gyroscope as an auxiliary device, and finally realizes the reconstruction of the carrier angular velocity information. Then, a rate observation vector reconstruction method assisted by external speed measurement information is designed to construct an objective function. Finally, the attitude matrix solution problem is converted into a Wahba attitude determination problem, and the carrier attitude matrix is ​​finally obtained to realize the initial alignment of the hemispherical resonant gyro strapdown inertial navigation system. The present invention can realize the initial alignment of the hemispherical resonant gyro strapdown inertial navigation system based on the force feedback mode while the carrier is in a moving state.

Description

Technical Field

[0001] The invention relates to a method for aligning a hemispherical resonant gyro strapdown inertial navigation system assisted by a micromechanical gyro and a Doppler odometer on the move, belonging to a signal processing method in the field of automation technology. Background Art

[0002] The invention is designed to be a method for aligning a hemispherical resonator gyro (HRG) strapdown inertial navigation system on the move, which is assisted by a micro-electromechanical systems (MEMS) and a Doppler log (DVL). More specifically, considering that the carrier angular velocity is large during the bow movement of a ship and the carrier angular velocity exceeds the measurement range of a force feedback type hemispherical resonator gyro, an angular velocity acquisition algorithm using a micro-electromechanical gyro as an auxiliary device is designed, and finally the reconstruction of the carrier angular velocity information is realized. Then, a rate observation vector reconstruction method assisted by external speed measurement information is designed to construct an objective function. Finally, the attitude matrix solving problem is converted into a Wahba attitude determination problem, and finally the carrier attitude matrix is ​​obtained, and the initial alignment of the hemispherical resonator gyro strapdown inertial navigation system is realized. The method belongs to a signal processing method in the field of automation technology, and can realize the initial alignment of the HRG strapdown inertial navigation system on the move based on the force feedback mode when the carrier is in the moving state.

[0003] The hemispherical resonator gyroscope is a new type of inertial navigation-grade solid gyroscope. It is a new type of vibration gyroscope that uses the Coriolis effect of standing waves excited on a hemispherical resonator to measure the angular velocity of the base rotation. Since the hemispherical resonator gyroscope has no high-speed moving parts, does not require temperature control, has low internal power consumption, and has the least potential failure factors, it has high measurement accuracy, super stability and reliability, good shock and vibration resistance and temperature performance. In particular, it has a working life of more than 15 years, and the reliability of 15 years of continuous work can reach 0.995. Based on the above advantages, the strapdown inertial navigation system constructed by the hemispherical resonator gyroscope will be one of the ideal choices for inertial navigation equipment for navigation.

[0004] However, compared with traditional laser gyroscopes and fiber optic gyroscopes, the measurement range of the force feedback mode HRG gyroscope is smaller. Although most of the movements of ocean vehicles are in a low angular velocity state, due to the influence of different sea conditions, the ocean vehicle may experience violent swinging movements during the alignment process of the moored state, and the angular velocity generated may exceed the measurement range of the force feedback mode HRG. Although the full-angle mode HRG has a larger measurement range, the current technology is immature, the domestic production capacity is low, and it is not suitable for large-scale equipment. In addition, the current measurement accuracy is lower than that of the force feedback mode HRG.

[0005] Although the measurement accuracy of MEMS gyro is low and cannot reach the measurement accuracy of HRG for angular rate, the angular rate measurement range is large and can be used as an angular rate measurement instrument when the angular rate exceeds the measurement range of HRG device. Therefore, MEMS gyro is selected as an auxiliary device to realize the alignment of HRG strapdown inertial navigation system. This will provide a strong guarantee for subsequent ship navigation.

[0006] When the ship is moving, the angular velocity caused by the superposition of angular motion and linear motion is much greater than the angular velocity of the earth's rotation. The accelerometer measurement information is disturbed, making the gyro and accelerometer outputs have a low signal-to-noise ratio, so it is impossible to directly extract the earth's rotation angular velocity vector and gravity vector from the gyro and accelerometer output information. At this time, the traditional analytical static base alignment method and the rocking base alignment method will not work. In addition, since the compass alignment and Kalman filter combined alignment methods need to meet the condition that the misalignment angle is a small angle when applied, it is impossible to complete the initial alignment under the conditions of arbitrary azimuth and heading angles of the rocking base.

[0007] Although the Earth's rotation angular velocity cannot be used directly to construct constraint equations when the ship is moving, the inertial system alignment method uses the gravity acceleration vectors in the inertial system at two or more moments to construct the corresponding constraint relationship, and then determines the attitude transformation matrix. Therefore, it is widely used for the initial alignment of the rocking base. In essence, the multi-vector inertial system alignment method based on the velocity integral form belongs to the category of least squares estimation, which has a good suppression effect on interference such as device noise and external environmental vibration.

[0008] Therefore, in order to solve the problem of initial alignment when the ship is moving, the present invention proposes a method for alignment of an HRG strapdown inertial navigation system assisted by a MEMS gyroscope. First, the angular velocity is collected as an auxiliary device to achieve reconstruction of the carrier angular velocity information; then a rate observation vector reconstruction method assisted by external speed measurement information is designed to construct an objective function. Finally, the attitude matrix solution problem is converted into a Wahba attitude determination problem, and the carrier attitude matrix is ​​finally obtained to achieve the initial alignment of the hemispherical resonant gyro strapdown inertial navigation system. This method belongs to a signal processing method in the field of automation technology, and can achieve the initial alignment of an HRG strapdown inertial navigation system based on a force feedback mode when the carrier is moving. Summary of the invention

[0009] The purpose of the present invention is to solve the problems existing in the prior art and further provide a method for aligning a hemispherical resonant gyro strapdown inertial navigation system assisted by a micromechanical gyro and a Doppler odometer while on the move.

[0010] The objective of the present invention is achieved through the following technical solutions:

[0011] A method for aligning a hemispherical resonant gyro strapdown inertial navigation system assisted by a micromechanical gyro and a Doppler odometer on the move comprises the following steps:

[0012] Step 1: Install a high-precision hemispherical resonant gyroscope and a micromechanical gyroscope in a force feedback mode on the ship, with the x-axis of the two gyroscopes pointing parallel to the starboard side of the ship, the y-axis pointing to the bow, and the z-axis pointing to the sky. The xyz-axis of the speed direction measured by the Doppler log is parallel to the xyz-axis of the gyroscope respectively; the three devices are connected to a computer equipped with data acquisition software respectively;

[0013] Step 2: During the alignment process of the ship, the speed information data measured by the hemispherical resonant gyro strapdown inertial navigation system, MEMS gyro and Doppler speed log are collected simultaneously;

[0014] Step 3: By setting a threshold, the data of the angular rate in the swing motion exceeding the HRG measurement range is judged, and the MEMS gyro output is used as the angular rate output value of the axis of the HRG strapdown inertial navigation system to achieve reconstruction of the carrier angular rate information;

[0015] Step 4: Reconstruct the speed observation vector with the assistance of external speed measurement information;

[0016] Step 5: By converting the attitude matrix solution problem into a Wahba attitude determination problem, the carrier attitude matrix is ​​finally obtained to achieve the initial alignment of the hemispherical resonant gyro strapdown inertial navigation system.

[0017] Step 6: Store the attitude matrix obtained by alignment into the navigation computer to complete the alignment process.

[0018] Furthermore, the force feedback mode HRG described in step 3 has high measurement accuracy, but the measurement range is limited, and the influence of acceleration during the movement cannot complete self-alignment. External auxiliary equipment is used to assist it in completing the alignment during movement. The specific method is:

[0019] 1) Simultaneously collect the angular rate data of the strapdown inertial navigation system HRG and the angular rate information measured by the coaxially mounted MEMS gyroscope, and set the threshold λ according to the HRG measurement range;

[0020] 2) Compare the HRG measurement value with the threshold and choose whether to use the MEMS output as alignment data. The specific method is as follows:

[0021]

[0022]

[0023]

[0024] Among them, IMUx, IMUy, and IMUz are the data of the three-axis gyroscope used for alignment, t is the time of data acquisition, HRGx, HRGy, and HRGz are the data output by the HRG three-axis gyroscope, MEMSx, MEMSy, and MEMSz are the data output by the MEMS three-axis gyroscope, and λ is the set threshold. The gyroscope data and acceleration data are used for the alignment of the rocking base.

[0025] Furthermore, in step 4, with the assistance of external speed measurement information, the speed observation vector is reconstructed. The specific method is as follows:

[0026] 1) According to the specific force equation:

[0027]

[0028] where v n Represents the speed information in the navigation coordinate system (n system), represents the velocity change rate in the navigation coordinate system, f b Represents the specific force information in the carrier coordinate system (b system), is the Earth's rotation angular rate in the navigation coordinate system, is the angular velocity of the navigation system relative to the earth coordinate system under the navigation system, g n Provides gravity information for navigation.

[0029] Will After transformation, we get:

[0030]

[0031] in

[0032]

[0033] For convenience of representation, for any three-dimensional column vector V = [V x V y V z ] T , use (V×) to represent the third-order matrix:

[0034]

[0035] Substitute the above formula and get:

[0036]

[0037] It is the angular velocity information of the carrier coordinate system (b system) relative to the inertial coordinate system (i system).

[0038] Integrating both sides yields:

[0039]

[0040] 2) Using α and β to represent both sides of the equation, we get:

[0041]

[0042]

[0043]

[0044] in:

[0045] g n(0) = -g[sinω ie tcosL(1-cosω ie t)sinLcosL 1-(1-cosω ie t)cos 2 L] T ;

[0046] g n(0) is the projection of gravity acceleration in the n(0) system, where t is the current time and L is the latitude information of the carrier's location;

[0047] α, β represent the velocity vector obtained by integrating the gravity vector in the carrier coordinate system b0 and the navigation coordinate system n0 at the initial moment, respectively.

[0048] Further, the alignment is achieved by using the inertial system alignment method described in step 5, and the specific method is as follows:

[0049] 1) According to the matrix chain rule, Expand into Calculate the three matrices obtained by decomposition respectively;

[0050] 2): Due to is a constant, that is, the n(t) system rotates with respect to the n(0) system. The above equation can be solved to get Expression:

[0051]

[0052] Where I is the identity matrix, ω ie is the Earth's rotation angular rate, and t is the current moment.

[0053] Secondly, the specific force output of the accelerometer is projected on the b(0) system as:

[0054]

[0055] in:

[0056]

[0057]

[0058]

[0059] In the above formula, Δθ1 and Δθ2 are the angular rate increment information obtained by gyro measurement. is the angle increment between the two sampling moments after compensation, t is the current moment, and tm is the moment when the previous angle increment compensation value is generated, that is, the two sampling moments before the two current t moments;

[0060] 3): According to the previous analysis results:

[0061]

[0062] Solving it as a Wahba problem, The quaternion representation of The recursive matrix K can be calculated by the Davenport-q recursive algorithm k The eigenvector corresponding to the maximum eigenvalue of is obtained:

[0063]

[0064] in:

[0065] δB k =β k α k T

[0066] where α k and β k are the discrete forms of α and β respectively;

[0067] In order to obtain the attitude matrix at the end of the rough alignment, the following formula can be used for calculation

[0068]

[0069] Based on this, the strapdown matrix is ​​obtained to complete the initial alignment of the ship while moving.

[0070] The beneficial effects of the present invention are:

[0071] The method proposed in the present invention solves the angular velocity measurement problem of the navigation system when the angular velocity amplitude exceeds the HRG measurement range, has a faster alignment convergence speed and better noise suppression capability, and has a good alignment convergence speed, providing a good initial condition for precise alignment.

[0072] The present invention proposes a method for alignment of a HRG strapdown inertial navigation system assisted by a MEMS gyroscope during movement. First, the MEMS gyroscope is used as an auxiliary device to collect angular velocity to achieve reconstruction of the carrier angular velocity information; then a rate observation vector reconstruction method assisted by external velocity measurement information is designed to construct an objective function. Finally, the attitude matrix solution problem is transformed into a Wahba attitude determination problem, and the carrier attitude matrix is ​​finally obtained to achieve the initial alignment of the hemispherical resonant gyro strapdown inertial navigation system. This method belongs to a signal processing method in the field of automation technology, and can achieve the initial alignment of the HRG strapdown inertial navigation system based on a force feedback mode while the carrier is moving.

[0073] The present invention is designed to be a method for aligning a hemispherical resonant gyro strapdown inertial navigation system assisted by a micromechanical gyro and a Doppler odometer. More specifically, considering that the carrier angular velocity is large during the bow movement of a ship and the carrier angular velocity exceeds the measurement range of a force feedback hemispherical resonant gyro, an angular velocity acquisition algorithm using a micromechanical gyro as an auxiliary device is designed to ultimately achieve reconstruction of the carrier angular velocity information. Then, a rate observation vector reconstruction method assisted by external velocity measurement information is designed to construct an objective function. Finally, the attitude matrix solution problem is converted into a Wahba attitude determination problem, and the carrier attitude matrix is ​​finally obtained to achieve initial alignment of a hemispherical resonant gyro strapdown inertial navigation system. The method belongs to a signal processing method in the field of automation technology, and can achieve initial alignment of a HRG strapdown inertial navigation system based on a force feedback mode when the carrier is in a traveling state. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 It is a schematic diagram of the process of the present invention.

[0075] Figure 2 is the attitude angle of the carrier during motion.

[0076] Figure 3 Alignment results for the strapdown inertial navigation system. DETAILED DESCRIPTION

[0077] The present invention will be further described in detail below in conjunction with the accompanying drawings: This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method is given, but the protection scope of the present invention is not limited to the following embodiments.

[0078] like Figures 1 to 3 As shown, the present embodiment involves a method for aligning a micromechanical gyro and a Doppler odometer-assisted hemispherical resonant gyro strapdown inertial navigation system on the move, and the method schematic diagram is shown in FIG. Figure 1 The object of the present invention is achieved by the following steps:

[0079] Step 1: Install a high-precision hemispherical resonant gyroscope and a micromechanical gyroscope in a force feedback mode on the ship, with the x-axis of the two gyroscopes pointing parallel to the starboard side of the ship, the y-axis pointing to the bow direction, and the z-axis pointing to the sky, and connect them to a computer equipped with data acquisition software;

[0080] Step 2: During the ship alignment process, data of the hemispherical resonant gyro strapdown inertial navigation system and the MEMS gyro are collected simultaneously;

[0081] Step 3: According to the HRG measurement range, by setting the threshold λ, determine the data of the angular rate in the swing motion exceeding the HRG measurement range, and choose whether to use the MEMS output as alignment data by the following formula:

[0082]

[0083]

[0084]

[0085] The reconstructed gyro data and the acceleration data of the inertial navigation system are used for the alignment of the rocking base.

[0086] Step 4: Reconstruct the speed observation vector with the help of external speed measurement information:

[0087]

[0088]

[0089]

[0090] in:

[0091] g n(0) = -g[sinω ie tcosL (1-cosω ie t)sinLcosL 1-(1-cosω ie t)cos 2 L] T ;

[0092] g n(0) is the projection of gravitational acceleration in the n(0) system.

[0093] α, β represent the velocity vector obtained by integrating the gravity vector in the carrier coordinate system b0 and the navigation coordinate system n0 at the initial moment, respectively.

[0094] Step 5: Use the inertial system alignment method to achieve alignment.

[0095] According to the matrix chain rule, Expand into Calculate the three matrices obtained by decomposition respectively;

[0096] because is a constant, that is, the n(t) system rotates with respect to the n(0) system. The above equation can be solved to get Expression:

[0097]

[0098] Use the following method to find:

[0099]

[0100]

[0101]

[0102] According to the previous analysis results:

[0103]

[0104] Solve it as a Wahba problem

[0105] The quaternion representation of The recursive matrix K can be calculated by the Davenport-q recursive algorithm k The eigenvector corresponding to the maximum eigenvalue of is obtained:

[0106]

[0107] in:

[0108] δB k =β k α k T

[0109] where α k and β k are the discrete forms of α and β respectively.

[0110] In order to obtain the attitude matrix at the end of the rough alignment, the following formula can be used for calculation

[0111]

[0112] Based on this, the strapdown matrix is ​​obtained to complete the initial alignment of the ship while moving.

[0113] Step 6: Store the attitude matrix obtained by alignment into the navigation computer to complete the alignment process.

[0114] The effect of the present invention can be verified by the following simulation:

[0115] The simulation experiment uses a gyro drift of 0.01° / h and an angular random walk of The full-angle mode hemispherical resonant gyro and accelerometer zero bias are 10 -4 g inertial device, the sampling frequency is 100Hz, the gyro angle measurement range is ±8° / h; the MEMS gyro drift is 0.5° / h, and the angle random walk is Since the reference value of the attitude can be obtained in real time in the simulation environment, as long as the comparative experiment is carried out under the same swinging conditions, the obtained alignment error can be used to evaluate the alignment performance of each algorithm. Therefore, the simulation sets the local latitude to 45.72° (Harbin), and the simulation time is 300s, of which the first 140s are uniformly accelerated, then turn counterclockwise at 9° / s for 10s, and finally perform uniformly accelerated motion for 150s. Specifically, the simulation sets the swing equilibrium position to 0° roll, 0° pitch, and 45° heading, with the initial phases all at 0°, and the swing motion is set to the following conditions:

[0116] The rolling amplitude is 2° and the period is 12s;

[0117] The pitch amplitude is 0.8° and the period is 7s;

[0118] The amplitude of the bow roll is 0.6° and the period is 7s.

[0119] The simulation results are as follows Figure 2 As shown, Figure 2 The three figures in the middle respectively represent the rocking base and roll, pitch and heading (north-west is positive).

[0120] The alignment result is as follows Figure 3 As shown, the roll error is -0.0025°, the pitch error is -0.0020°, and the heading error is 0.3213°. Therefore, the method proposed in the present invention solves the angular velocity measurement problem of the navigation system when the angular velocity amplitude exceeds the HRG measurement range, has a faster alignment convergence speed and better noise suppression capability, and has a better alignment convergence speed. Since the final alignment result is affected by the measurement noise of the inertial navigation system accelerometer and the DVL measurement noise at the same time, there will be large noise fluctuations. At the same time, as the alignment time increases, the influence of noise will continue to decrease, and the fluctuation of the attitude estimation results will continue to decrease. In order to achieve better convergence of the attitude estimation results, the alignment time can be appropriately increased. Since the error values ​​are all small angle information, the linearization requirements are met, which provides a good initial condition for precise alignment.

[0121] The above are only preferred specific embodiments of the present invention, which are all different implementations based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for aligning a hemispherical resonant gyro strapdown inertial navigation system assisted by a micromechanical gyro and a Doppler odometer on the move, characterized in that: The following steps are involved: Step 1: Install a high-precision hemispherical resonant gyroscope and a micromechanical gyroscope in a force feedback mode on the ship, with the x-axis of the two gyroscopes pointing parallel to the starboard side of the ship, the y-axis pointing to the bow, and the z-axis pointing to the sky. The xyz-axis of the speed direction measured by the Doppler log is parallel to the xyz-axis of the gyroscope respectively; the three devices are connected to a computer equipped with data acquisition software respectively; Step 2: During the alignment process of the ship, the speed information data measured by the hemispherical resonant gyro strapdown inertial navigation system, MEMS gyro and Doppler speed log are collected simultaneously; Step 3: By setting a threshold, the data of the angular rate in the swing motion exceeding the HRG measurement range is judged, and the MEMS gyro output is used as the angular rate output value of the axis of the HRG strapdown inertial navigation system to achieve reconstruction of the carrier angular rate information; Step 4: Reconstruct the speed observation vector with the assistance of external speed measurement information; Step 5: Convert the attitude matrix solution problem into the Wahba attitude determination problem, and finally obtain the carrier attitude matrix to achieve the initial alignment of the hemispherical resonant gyro strapdown inertial navigation system; Step 6: Store the attitude matrix obtained by alignment into the navigation computer to complete the alignment process.

2. The method for aligning a micromechanical gyro and a Doppler odometer-assisted hemispherical resonant gyro strapdown inertial navigation system on the move according to claim 1, characterized in that: The force feedback mode HRG described in step 3 has high measurement accuracy, but the measurement range is limited, and the influence of acceleration during the movement cannot complete self-alignment; external auxiliary equipment is used to assist it in completing the alignment during movement. The specific method is as follows: 1) Simultaneously collect the angular rate data of the strapdown inertial navigation system HRG and the angular rate information measured by the coaxially mounted MEMS gyroscope, and set the threshold λ according to the HRG measurement range; 2) Compare the HRG measurement value with the threshold and choose whether to use the MEMS output as alignment data. The specific method is as follows: Among them, IMUx, IMUy, IMUz are the data of the three-axis gyroscope used for alignment, t is the time of data acquisition, HRGx, HRGy, HRGz are the data output by the HRG three-axis gyroscope, MEMSx, MEMSy, MEMSz are the data output by the MEMS three-axis gyroscope, and λ is the set threshold; the gyroscope data and acceleration data are used for the alignment of the rocking base.

3. The method for aligning a micromechanical gyro and a Doppler odometer-assisted hemispherical resonant gyro strapdown inertial navigation system on the move according to claim 1, characterized in that: Step 4: Reconstruct the speed observation vector with the help of external speed measurement information. The specific method is as follows: 1) According to the specific force equation: where v n Indicates the speed information in the navigation coordinate system (n system), represents the velocity change rate in the navigation coordinate system, f b Represents the specific force information in the carrier coordinate system (b system), is the Earth's rotation angular rate in the navigation coordinate system, is the angular velocity of the navigation system relative to the earth coordinate system under the navigation system, g n Provide gravity information for navigation system; Will After transformation, we get: in For convenience of representation, for any three-dimensional column vector V = [V x V y V z ] T , use (V×) to represent the third-order matrix: Substitute the above formula and get: It is the angular velocity information of the carrier coordinate system (b system) relative to the inertial coordinate system (i system); Integrating both sides gives: 2) Using α and β to represent both sides of the equation, we get: in: g n(0) =-g[sinω ie tcosL (1-cosω ie t)sinLcosL 1-(1-cosω ie t)cos 2 L] T ; g n(0) is the projection of gravity acceleration in the n(0) system, where t is the current time and L is the latitude information of the carrier's location; α, β represent the velocity vector obtained by integrating the gravity vector in the carrier coordinate system b0 and the navigation coordinate system n0 at the initial moment, respectively.

4. The method for aligning a micromechanical gyro and a Doppler odometer-assisted hemispherical resonant gyro strapdown inertial navigation system on the move according to claim 1, characterized in that: The alignment method described in step 5 is to use the inertial system alignment method to achieve alignment. The specific method is as follows: 1) According to the matrix chain rule, Expand into Calculate the three matrices obtained by decomposition respectively; 2): Due to is a constant, that is, the n(t) system rotates with respect to the n(0) system. The above equation can be solved to get Expression: Where I is the identity matrix, ω ie is the Earth's rotation angular rate, t is the current moment; Secondly, the specific force output of the accelerometer is projected on the b(0) system as: in: In the above formula, Δθ1 and Δθ2 are the angular rate increment information obtained by gyro measurement. is the angle increment between the two sampling moments after compensation, t is the current moment, and tm is the moment when the previous angle increment compensation value is generated, that is, the two sampling moments before the two current t moments; 3): According to the previous analysis results: Solving it as a Wahba problem, The quaternion representation of The recursive matrix K can be calculated by the Davenport-q recursive algorithm k The eigenvector corresponding to the maximum eigenvalue of is obtained: in: δB k =b k a k T where α k and β k are the discrete forms of α and β respectively; In order to obtain the attitude matrix at the end of the rough alignment, the following formula can be used for calculation Based on this, the strapdown matrix is ​​obtained to complete the initial alignment of the ship while moving.

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