Marine inertial navigation coarse alignment method based on GNSS assistance

Abstract

The invention discloses a marine inertial navigation coarse alignment method based on GNSS assistance, and the method specifically comprises the following steps: S1, installing inertial navigation equipment and GNSS equipment on a ship body, obtaining angular velocity information of a gyroscope and acceleration information of an accelerometer through the inertial navigation equipment, and obtaining position information and speed information of the ship body through measurement of the GNSS equipment; s2, obtaining acceleration information # imgabs0 # S3 according to the speed difference measured by the GNSS; S3, obtaining projection data of the earth rotation angular speed and the involved speed in a navigation coordinate system according to the speed position measured by the GNSS; s4, performing IIR (Infinite Impulse Response) low-pass filtering on the obtained projection data under the navigation coordinate system; and S5, carrying out iterative calculation on projection data under the navigation coordinate system after IIR (Infinite Impulse Response) low-pass filtering to obtain an inertial navigation coarse alignment result. According to the method disclosed by the invention, the mutual conversion relation between the GNSS and the marine inertial navigation system is determined in a differential mode by utilizing the marine GNSS speed measurement information, the integral complex calculation amount is reduced, and the initial alignment is quickly and accurately completed.

Description

Technical Field

[0001] The invention belongs to the field of inertial navigation technology application, and in particular relates to a marine inertial navigation coarse alignment method based on GNSS assistance. Background Art

[0002] The inertial navigation system is a dead reckoning system. Initial alignment is the prerequisite for inertial navigation. The quality of initial alignment will directly affect the navigation accuracy of the system. Traditional initial alignment is generally performed under the constraints of a static base, while rapid dynamic base initial alignment can effectively enhance the maneuverability of various platforms, improve their responsiveness and survivability, and is of great significance in military applications.

[0003] Initial alignment is an important working stage of inertial navigation. Before the inertial navigation system enters the navigation state, initial alignment provides the inertial navigation system with indispensable initial attitude values. Generally speaking, the initial alignment of inertial navigation is divided into two stages: coarse alignment and fine alignment. The purpose of coarse alignment is to obtain a set of rough attitude angles within a certain period of time, and the accuracy of the rough attitude angles is required to be as high as possible, in preparation for the subsequent fine alignment stage.

[0004] The commonly used ship inertial navigation uses an analytical coarse alignment method based on dual-vector attitude determination, which can quickly obtain coarse alignment results, but the calculation amount is large. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the above-mentioned prior art and to provide a GNSS-assisted ship inertial navigation coarse alignment method. The present invention utilizes ship GNSS speed measurement information to determine the mutual conversion relationship between GNSS and the ship inertial navigation system by differential means, thereby reducing the complex calculation amount of integration, being able to quickly and accurately complete the initial alignment with high alignment accuracy.

[0006] In order to achieve the above invention purpose, the technical solution provided by the present invention is as follows:

[0007] A GNSS-assisted marine inertial navigation rough alignment method, the method specifically comprising the following steps:

[0008] S1, installing an inertial navigation device and a GNSS device on the hull, obtaining angular velocity information of the gyroscope and acceleration information of the accelerometer through the inertial navigation device, and obtaining hull position information and speed information through the GNSS device;

[0009] S2, obtain acceleration information based on the velocity difference measured by GNSS

[0010] S3, obtaining projection data of the earth's rotation angular velocity and the associated velocity in the navigation coordinate system according to the velocity position measured by the GNSS;

[0011] S4, performing IIR low-pass filtering on the acquired projection data in the navigation coordinate system;

[0012] S5, iteratively calculating the projection data in the navigation coordinate system after IIR low-pass filtering to obtain the inertial navigation coarse alignment result.

[0013] Furthermore, the acceleration information is obtained by differentially measuring the velocity of the GNSS. The specific acquisition is:

[0014]

[0015] Among them, g n is the acceleration due to gravity, L is the latitude, v E is the eastward velocity, v N is the northward velocity, ω ie is the Earth's rotation angular velocity, is the attitude transfer matrix between the carrier coordinate system b and the geographic coordinate system n, f b is the accelerometer specific force, is the Coriolis acceleration caused by the carrier motion and the Earth's rotation; is the centripetal acceleration caused by the motion of the carrier, and R is the radius of the earth.

[0016] Furthermore, the projection data of the earth's rotation angular velocity and the associated velocity in the navigation coordinate system are obtained by: obtaining the acceleration information after the velocity difference measured by GNSS The formula is converted into:

[0017]

[0018] make

[0019] The projection data in the navigation coordinate system can be obtained and

[0020] Furthermore, the projection data is subjected to IIR low-pass filtering as follows:

[0021] The projection data obtained in the navigation coordinate system and conduct Filtering and

[0022] Furthermore, the iterative calculation to obtain the inertial navigation coarse alignment result is specifically:

[0023]

[0024] Among them, tk1 is the middle time of alignment, and tk2 is the end time of alignment; is the attitude transfer matrix from the start time of coarse alignment to the end time of coarse alignment; and They are the projections of the acceleration measured by GNSS in the navigation system n and the acceleration measured by the accelerometer in the b0 system respectively.

[0025] Based on the above scheme, the device of the present invention has achieved positive and beneficial effects through practice:

[0026] 1. The present invention discloses a GNSS-assisted ship inertial navigation rough alignment method, which utilizes ship GNSS speed measurement information and determines the mutual conversion relationship between GNSS and ship inertial navigation system by differential method, thereby reducing the complex calculation amount of integration, and can quickly and accurately complete the initial alignment with high alignment accuracy. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by specific examples. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0028] The present invention relates to a GNSS-assisted marine inertial navigation coarse alignment method, which specifically comprises the following steps:

[0029] S1, installing an inertial navigation device and a GNSS device on the hull, obtaining angular velocity information of the gyroscope and acceleration information of the accelerometer through the inertial navigation device, and obtaining hull position information and speed information through the GNSS device;

[0030] S2, obtain acceleration information based on the velocity difference measured by GNSS

[0031] S3, obtaining projection data of the earth's rotation angular velocity and the associated velocity in the navigation coordinate system according to the velocity position measured by the GNSS;

[0032] S4, performing IIR low-pass filtering on the acquired projection data in the navigation coordinate system;

[0033] S5, iteratively calculating the projection data in the navigation coordinate system after IIR low-pass filtering to obtain the inertial navigation coarse alignment result.

[0034] The GNSS measures the velocity differential to obtain acceleration information The specific acquisition is:

[0035]

[0036] Among them, g n is the acceleration due to gravity, L is the latitude, v E is the eastward velocity, v N is the northward velocity, ω ie is the Earth's rotation angular velocity, is the attitude transfer matrix between the carrier coordinate system b and the geographic coordinate system n, f b is the accelerometer specific force, is the Coriolis acceleration caused by the carrier motion and the Earth's rotation; is the centripetal acceleration caused by the motion of the carrier, and R is the radius of the earth.

[0037] Furthermore, the projection data of the earth's rotation angular velocity and the associated velocity in the navigation coordinate system are obtained by: obtaining the acceleration information after the velocity difference measured by GNSS The formula is converted into:

[0038]

[0039] make

[0040] The projection data in the navigation coordinate system can be obtained and

[0041] The projection data is subjected to IIR low-pass filtering specifically as follows:

[0042] The projection data obtained in the navigation coordinate system and conduct Filtering and

[0043] The iterative calculation to obtain the inertial navigation coarse alignment result is specifically:

[0044]

[0045] Among them, tk1 is the middle time of alignment, and tk2 is the end time of alignment; is the attitude transfer matrix from the start time of coarse alignment to the end time of coarse alignment; and They are the projections of the acceleration measured by GNSS in the navigation system n and the acceleration measured by the accelerometer in the b0 system respectively.

[0046] Example

[0047] Step (1): prepare an inertial navigation device (including an inertial measurement unit and a navigation computer circuit board) and a GNSS receiver; the inertial navigation device is used to obtain angular velocity and acceleration information measured by a gyroscope and an accelerometer; the GNSS receiver is used to measure the position and velocity information of the hull; the navigation calculation board is used to receive the angular velocity and acceleration information and the GNSS information;

[0048] Step (2): Save various key data, including gyro and accelerometer information after inertial navigation compensation, and position and velocity information measured by GNSS;

[0049] Step (3): Obtain acceleration information based on the velocity difference measured by GNSS

[0050] Step (4): Calculate the projection of the Earth's rotational angular velocity and the associated velocity in the navigation coordinate system based on the velocity position measured by the GNSS;

[0051] Step (5): performing an IIR low-pass filter on the projection of the GNSS specific force obtained by GNSS differential in the navigation coordinate system;

[0052] Step (6): iteratively calculate the projection of the GNSS specific force in the navigation coordinate system and the projection of the GNSS specific force in the body coordinate system;

[0053] Step (7): Iteratively calculate the coarse alignment result of the inertial navigation device.

[0054] The formula for iteratively calculating the rough alignment result of the inertial navigation device in step (7) can be expressed as:

[0055]

[0056] Among them, tk1 is the middle time of alignment, and tk2 is the end time of alignment; is the attitude transfer matrix from the start time of coarse alignment to the end time of coarse alignment; and They are the projections of the acceleration measured by GNSS in the navigation system n and the acceleration measured by the accelerometer in the b0 system respectively.

[0057] Due to the irregular low-frequency motion of the hull under the action of waves, the ship's inertial navigation angular velocity and angular velocity output are superimposed with irregular noise signals. The present invention eliminates the influence of noise signals by using a wavelet denoising method. The signal is decomposed into components of different frequencies for denoising, and useful signals are extracted and noise signals are removed according to the intensity of the noise in the frequency domain. The entire selection process can be achieved by setting a threshold. Signals above the threshold are considered useful signals and will be retained, while signals below the threshold are replaced with zero and eliminated.

[0058] ω(k)=f(k)+ε×e(k),k=0,1,2,…n-1 (2)

[0059] Among them, ω(k) is the noise data, f(k) is the low-frequency effective data, e(k) is the high-frequency noise, and ε is the noise standard deviation.

[0060]

[0061] Transforming formula (3) yields:

[0062]

[0063] Right now:

[0064]

[0065] in:

[0066] It can be obtained by the velocity difference measured by GNSS, g n is the acceleration due to gravity, It can also be calculated through GNSS information;

[0067] Latitude L, eastward speed v E , northward speed v N All are obtained by GNSS.

[0068] make Will get Perform IIR low-pass filtering to obtain make

[0069] in: The initial value is the identity matrix.

[0070] Will get Perform IIR low-pass filtering to obtain

[0071]

[0072] At tk1 and tk2, we have:

[0073] or:

[0074] The quaternion representations are:

[0075]

[0076] After sorting, we get

[0077]

[0078] in: This equation has a least squares solution, and the optimal solution satisfies:

[0079] The constraints are: Q T Q=1

[0080]

[0081] After solving the quaternion Q, the attitude transfer matrix can be calculated That is to say, the inertial navigation coarse alignment is completed.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A GNSS-assisted marine inertial navigation coarse alignment method, characterized in that: The method specifically comprises the following steps: S1, installing an inertial navigation device and a GNSS device on the hull, obtaining angular velocity information of the gyroscope and acceleration information of the accelerometer through the inertial navigation device, and obtaining hull position information and speed information through the GNSS device; S2, obtain acceleration information based on the velocity difference measured by GNSS S3, obtaining projection data of the earth's rotation angular velocity and the associated velocity in the navigation coordinate system according to the velocity position measured by the GNSS; S4, performing IIR low-pass filtering on the acquired projection data in the navigation coordinate system; S5, iteratively calculating the projection data in the navigation coordinate system after IIR low-pass filtering to obtain the inertial navigation coarse alignment result.

2. The method for coarse alignment of marine inertial navigation based on GNSS assistance according to claim 1, characterized in that: The GNSS measures the velocity differential to obtain acceleration information The specific acquisition is: Among them, g n is the acceleration due to gravity, L is the latitude, v E is the eastward velocity, v N is the northward velocity, ω ie is the Earth's rotation angular velocity, is the attitude transfer matrix between the carrier coordinate system b and the geographic coordinate system n, f b is the accelerometer specific force, is the Coriolis acceleration caused by the carrier motion and the Earth's rotation; is the centripetal acceleration caused by the motion of the carrier, and R is the radius of the earth.

3. The method for coarse alignment of marine inertial navigation based on GNSS assistance according to claim 2, characterized in that: The projection data of the earth's rotation angular velocity and the associated velocity in the navigation coordinate system are obtained by: obtaining the acceleration information based on the velocity difference measured by GNSS The formula is converted into: make The projection data in the navigation coordinate system can be obtained and 4. The method for coarse alignment of marine inertial navigation based on GNSS assistance according to claim 3 is characterized in that: The projection data is subjected to IIR low-pass filtering specifically as follows: The projection data obtained in the navigation coordinate system and conduct Filtering and 5. The method for coarse alignment of marine inertial navigation based on GNSS assistance according to claim 4 is characterized in that: The iterative calculation to obtain the inertial navigation coarse alignment result is specifically: Among them, tk1 is the middle time of alignment, and tk2 is the end time of alignment; is the attitude transfer matrix from the start time of coarse alignment to the end time of coarse alignment; and They are the projections of the acceleration measured by GNSS in the navigation system n and the acceleration measured by the accelerometer in the b0 system respectively.

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