Calibration method and device of two-dimensional doppler velocimeter, computer equipment and medium

Abstract

The application belongs to the technical field of integrated navigation and relates to a two-dimensional Doppler velocimeter calibration method and device, computer equipment and medium. The method comprises the following steps: obtaining relevant parameters of a two-dimensional laser Doppler velocimeter to obtain error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system; converting the error velocity to a carrier coordinate system and then to a navigation coordinate system to obtain error velocity in the navigation coordinate system, and then obtaining an error model of the two-dimensional laser Doppler velocimeter; constructing an error model of a strapdown inertial navigation system; constructing a Kalman filter, taking the global positioning system as a reference, taking the velocity error, position error of the strapdown inertial navigation system and the velocity error of the two-dimensional laser Doppler velocimeter in the navigation coordinate system as observation quantities, estimating the state vector of the integrated navigation system and calibrating it. The method is not limited by the directions of the two beams of the two-dimensional laser Doppler velocimeter.

Description

Technical Field

[0001] This application relates to the field of integrated navigation technology, and in particular to calibration methods, apparatus, computer equipment and media for two-dimensional Doppler velocimeters. Background Technology

[0002] Integrated navigation systems require the fusion of information from multiple sensors to leverage the strengths of each sensor. In the field of land-based integrated navigation, laser Doppler velocimeters are high-precision speed sensors. As non-contact measurement sensors, they offer advantages such as good spatial resolution, fast dynamic response, wide velocity range, and high directional sensitivity, and are expected to find widespread application in land-based integrated navigation.

[0003] In existing technologies, one-dimensional laser Doppler velocimeters have been used on a small scale in the field of land-based integrated navigation in recent years, with good results. Although one-dimensional laser Doppler velocimeters cannot provide speed and position information under a navigation system like the Global Positioning System (GPS), they are completely autonomous and do not require external signals. Compared with odometers, one-dimensional laser Doppler velocimeters have higher measurement accuracy and advantages such as non-contact measurement, good spatial resolution, fast dynamic response, wide measurement range, and high directional sensitivity. Compared with one-dimensional laser Doppler velocimeters, two-dimensional laser Doppler velocimeters can provide the vehicle's azimuth velocity. In integrated navigation systems, accurate azimuth velocity can effectively suppress the divergence of navigation system altitude errors. Therefore, compared with one-dimensional laser Doppler velocimeters, integrated navigation systems composed of two-dimensional laser Doppler velocimeters can provide more accurate altitude information.

[0004] However, the tilt angle of the actual output optical path of the laser Doppler velocimeter deviates from the design value, leading to scaling factor error. In integrated navigation systems, the coordinate system of the laser Doppler velocimeter is offset from that of the inertial navigation system, caused by the installation error angle of the laser Doppler velocimeter. In integrated navigation systems, the measurement error of the laser Doppler velocimeter is mainly caused by the scaling factor error and the installation error angle. In integrated navigation systems composed of a laser Doppler velocimeter and an inertial navigation system, to obtain higher navigation accuracy, it is necessary to accurately calibrate the laser Doppler velocimeter beforehand; the quality of the calibration directly affects the positioning accuracy of the integrated navigation system.

[0005] The existing calibration method for two-dimensional laser Doppler velocimeters is based on the condition that the two beams of the two-dimensional laser Doppler velocimeter are emitted as mirror images. When the two beams no longer meet the mirror image condition, the beam deviation angle of the two-dimensional laser Doppler velocimeter may be too large, which may cause the conventional Kalman filter to be unable to accurately estimate it. Summary of the Invention

[0006] Therefore, it is necessary to provide a calibration method, device, computer equipment, and medium for two-dimensional Doppler velocimeters to address the aforementioned technical problems. This would enable the calibration of two-dimensional laser Doppler velocimeters in land-based integrated navigation systems, without being limited by the emission direction of the two beams of the two-dimensional laser Doppler velocimeter, thereby improving navigation accuracy.

[0007] The calibration method for a two-dimensional Doppler velocimeter includes:

[0008] The beam wavelength, Doppler frequency shift of the first beam, Doppler frequency shift of the second beam, design tilt angle of the first beam, and design tilt angle of the second beam of the two-dimensional laser Doppler velocimeter are obtained. The forward error velocity and upward error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system are obtained, and the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system is also obtained.

[0009] The error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system is transformed to the carrier coordinate system to obtain the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system; the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system is transformed to the navigation coordinate system to obtain the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system.

[0010] An error model for a strapdown inertial navigation system is constructed. Based on the error parameters of a two-dimensional laser Doppler velocimeter and the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, the error model of the two-dimensional laser Doppler velocimeter is obtained.

[0011] Based on the error models of the two-dimensional laser Doppler velocimeter and the strapdown inertial navigation system, a Kalman filter is constructed. Using the Global Positioning System (GPS) as the reference, and taking the velocity error and position error of the strapdown inertial navigation system, as well as the velocity error of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, as the observations, the state vector of the combined navigation system composed of the two-dimensional laser Doppler velocimeter and the strapdown inertial navigation system is estimated. The two-dimensional laser Doppler velocimeter is then calibrated based on the estimation results.

[0012] In one embodiment, the beam wavelength, Doppler frequency shift of the first beam, Doppler frequency shift of the second beam, design tilt angle of the first beam, and design tilt angle of the second beam of the two-dimensional laser Doppler velocimeter are obtained to obtain the forward error velocity and upward error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system. The error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system includes:

[0013] By acquiring the beam wavelength, Doppler frequency shift of the first beam, and Doppler frequency shift of the second beam from a two-dimensional laser Doppler velocimeter, the velocities in the first beam direction and the second beam direction can be obtained:

[0014]

[0015]

[0016] In the formula, υ1 is the velocity along the direction of the first beam, υ2 is the velocity along the direction of the second beam, and λ is the beam wavelength of the two-dimensional laser Doppler velocimeter. The Doppler frequency shift measured for the first beam and The Doppler frequency shift measured for the second beam;

[0017] The design tilt angles of the first and second beams are obtained. Based on these angles, the velocities along the first and second beams, and the velocities along the second beams, the forward and upward error velocities of the two-dimensional laser Doppler velocimeter in its own coordinate system are calculated. Finally, the overall error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system is also obtained.

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025] In the formula, This represents the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system. The forward error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system. The astronomical error velocity of the two-dimensional laser Doppler velocimeter. δK i The scaling factor error is caused by the deviation between the design tilt angle and the actual tilt angle. The design tilt angle of the first beam of the two-dimensional laser Doppler velocimeter. The tilt angle is the design angle of the second beam of the two-dimensional laser Doppler velocimeter.

[0026] In one embodiment, the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system is transformed to the carrier coordinate system to obtain the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system, including:

[0027]

[0028]

[0029] φ m =[φ mx φ my φ mz ] T

[0030] In the formula, Let I3 represent the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system, m represent the coordinate system of the two-dimensional laser Doppler velocimeter, b represent the carrier coordinate system, and φ represent the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system. m φ represents the installation error angle between the coordinate system of the two-dimensional laser Doppler velocimeter and the coordinate system of the carrier. mx For the pitch installation error angle, φ my For the roll installation error angle, φ mz The heading installation error angle is represented by ×, which indicates the matrix cross product. This represents the attitude transformation matrix from the m-frame to the b-frame.

[0031] In one embodiment, the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system is transformed to the navigation coordinate system to obtain the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, including:

[0032]

[0033]

[0034] In the formula, Let φ represent the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, where n represents the navigation coordinate system and φ represents the attitude error angle of the inertial navigation system. This represents the attitude transformation matrix from the b-system to the n-system.

[0035] In one embodiment, the error model of the two-dimensional laser Doppler velocimeter is obtained based on the error parameters of the two-dimensional laser Doppler velocimeter and the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, including:

[0036] because:

[0037]

[0038]

[0039] δK=[δK1δK2δK3δK4] T

[0040] therefore:

[0041]

[0042]

[0043] In the formula, This represents the true velocity of the laser Doppler velocimeter in the n-frame. This represents the actual velocity of the laser Doppler velocimeter in the b-frame. This is the error model for a two-dimensional laser Doppler velocimeter.

[0044] In one embodiment, constructing an error model for a strapdown inertial navigation system includes:

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052] in:

[0053] υ n =[υ E υ N υ U ] T

[0054] δυ n =[δυ E δυ N δυ U ] T

[0055]

[0056]

[0057]

[0058] In the formula, f n υ represents the projection of the specific force obtained from the accelerometer output into the navigation coordinate system. n For the speed information of the strapdown inertial navigation system, υ E υ N υ Uδυ represents the eastward velocity, northward velocity, and upward velocity, respectively. n R represents the velocity error of the strapdown inertial navigation system, where L, λ, and h represent Earth's latitude, longitude, and altitude, respectively. M and R N ω represents the radii of curvature of the Earth's meridian and geoid at the location of the carrier, respectively. ie It represents the angular velocity of Earth's rotation.

[0059] In one embodiment, a Kalman filter is constructed based on the error model of the two-dimensional laser Doppler velocimeter and the error model of the strapdown inertial navigation system. The estimation of the state vector of the integrated navigation system composed of the two-dimensional laser Doppler velocimeter and the strapdown inertial navigation system includes:

[0060] The three installation error angles, four scaling factor errors, inertial navigation attitude error, velocity error, position error, gyroscope measurement error, and accelerometer measurement error of the two-dimensional laser Doppler velocimeter are collectively used to construct the state vector of the integrated navigation system:

[0061]

[0062] In the formula, X(t) is the state vector of the integrated navigation system. For inertial navigation attitude error, δυ n δP represents the velocity error, and δP represents the position error. For gyroscope measurement error, For accelerometer measurement error, φ mx φ my φ mz These are the three installation error angles of the two-dimensional laser Doppler velocimeter, and δK1, δK2, δK3, and δK4 are the four scaling factor errors.

[0063] Using the output velocity and position of the Global Positioning System (GPS) as a reference, and the velocity and position errors of the strapdown inertial navigation system (SINS) and the velocity error of the two-dimensional laser Doppler velocimeter in the navigation coordinate system as observations, the state vector is estimated:

[0064]

[0065] In the formula, υ SINS P is the output speed of the strapdown inertial navigation system. SINS For the output position of the strapdown inertial navigation system, υ GPS p represents the output speed of the Global Positioning System. GPS Let z(t) be the position of the Global Positioning System, z(t) be the filtered observation, H(t) be the measurement matrix of the filter, and V(t) be the measurement noise vector.

[0066] The calibration device for a two-dimensional Doppler velocimeter includes:

[0067] The acquisition module is used to acquire the beam wavelength, Doppler frequency shift of the first beam, Doppler frequency shift of the second beam, design tilt angle of the first beam, and design tilt angle of the second beam of the two-dimensional laser Doppler velocimeter, to obtain the forward error velocity and upward error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system, and to obtain the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system.

[0068] The conversion module is used to convert the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system to the carrier coordinate system, thereby obtaining the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system; and to convert the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system to the navigation coordinate system, thereby obtaining the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system.

[0069] The modeling module is used to construct the error model of the strapdown inertial navigation system; based on the error parameters of the two-dimensional laser Doppler velocimeter and its error velocity in the navigation coordinate system, the error model of the two-dimensional laser Doppler velocimeter is obtained.

[0070] The navigation module is used to construct a Kalman filter based on the error models of the two-dimensional laser Doppler velocimeter and the strapdown inertial navigation system. Using the Global Positioning System as a reference, and taking the velocity error and position error of the strapdown inertial navigation system and the velocity error of the two-dimensional laser Doppler velocimeter in the navigation coordinate system as observations, it estimates the state vector of the combined navigation system composed of the two-dimensional laser Doppler velocimeter and the strapdown inertial navigation system, and calibrates the two-dimensional laser Doppler velocimeter based on the estimation results.

[0071] A computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program performing the following steps:

[0072] The beam wavelength, Doppler frequency shift of the first beam, Doppler frequency shift of the second beam, design tilt angle of the first beam, and design tilt angle of the second beam of the two-dimensional laser Doppler velocimeter are obtained. The forward error velocity and upward error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system are obtained, and the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system is also obtained.

[0073] The error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system is transformed to the carrier coordinate system to obtain the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system; the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system is transformed to the navigation coordinate system to obtain the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system.

[0074] An error model for a strapdown inertial navigation system is constructed. Based on the error parameters of a two-dimensional laser Doppler velocimeter and the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, the error model of the two-dimensional laser Doppler velocimeter is obtained.

[0075] Based on the error models of the two-dimensional laser Doppler velocimeter and the strapdown inertial navigation system, a Kalman filter is constructed. Using the Global Positioning System (GPS) as the reference, and taking the velocity error and position error of the strapdown inertial navigation system, as well as the velocity error of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, as the observations, the state vector of the combined navigation system composed of the two-dimensional laser Doppler velocimeter and the strapdown inertial navigation system is estimated. The two-dimensional laser Doppler velocimeter is then calibrated based on the estimation results.

[0076] A computer-readable storage medium having a computer program stored thereon, the computer program performing the following steps when executed by a processor:

[0077] The beam wavelength, Doppler frequency shift of the first beam, Doppler frequency shift of the second beam, design tilt angle of the first beam, and design tilt angle of the second beam of the two-dimensional laser Doppler velocimeter are obtained. The forward error velocity and upward error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system are obtained, and the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system is also obtained.

[0078] The error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system is transformed to the carrier coordinate system to obtain the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system; the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system is transformed to the navigation coordinate system to obtain the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system.

[0079] An error model for a strapdown inertial navigation system is constructed. Based on the error parameters of a two-dimensional laser Doppler velocimeter and the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, the error model of the two-dimensional laser Doppler velocimeter is obtained.

[0080] Based on the error models of the two-dimensional laser Doppler velocimeter and the strapdown inertial navigation system, a Kalman filter is constructed. Using the Global Positioning System (GPS) as the reference, and taking the velocity error and position error of the strapdown inertial navigation system, as well as the velocity error of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, as the observations, the state vector of the combined navigation system composed of the two-dimensional laser Doppler velocimeter and the strapdown inertial navigation system is estimated. The two-dimensional laser Doppler velocimeter is then calibrated based on the estimation results.

[0081] The calibration method for the aforementioned two-dimensional Doppler velocimeter derives the velocity expressions of the two-dimensional laser Doppler velocimeter in its own coordinate system in the forward and upward directions based on the two outputs of the velocimeter. It also analyzes the error terms of the two-dimensional laser Doppler velocimeter during integrated navigation (including four scaling factor errors δK1, δK2, δK3, and δK4, and three installation error angles φ). mx φ my φ mz This paper integrates a two-dimensional laser Doppler velocimeter, a global positioning system (GPS), and an inertial navigation system. It analyzes the output velocity of the two-dimensional laser Doppler velocimeter in different coordinate systems and the error terms causing the measurement error. The error terms are used as the state vector, and Kalman filtering is used to estimate the error terms. High-precision velocity and position information from the GPS are used as part of the filtering observations to more accurately and quickly calibrate the error terms of the two-dimensional laser Doppler velocimeter. The error terms of the two-dimensional laser Doppler velocimeter are then used as the state vector. Kalman filtering is employed to estimate the error terms, and high-precision velocity and position information from the GPS are used as part of the filtering observations to more accurately and quickly calibrate the error terms of the two-dimensional laser Doppler velocimeter. This invention enables precise calibration of a two-dimensional laser Doppler velocimeter. The precisely calibrated two-dimensional laser Doppler velocimeter can provide the integrated navigation system with accurate velocity information in both the forward and upward directions of the carrier, especially the more accurate upward velocity information. This allows the integrated navigation system to obtain more accurate altitude information, giving the two-dimensional laser Doppler velocimeter a significant advantage in elevation measurement compared to one-dimensional laser Doppler velocimeters and odometers. Attached Figure Description

[0082] Figure 1 This is an application scenario diagram of the calibration method for a two-dimensional Doppler velocimeter in one embodiment;

[0083] Figure 2 This is a flowchart illustrating the calibration method of a two-dimensional Doppler velocimeter in one embodiment;

[0084] Figure 3 This is an example of the installation location and output optical path diagram of a two-dimensional laser Doppler velocimeter in an integrated navigation system.

[0085] Figure 4 This is a structural block diagram of the calibration device for a two-dimensional Doppler velocimeter in one embodiment;

[0086] Figure 5 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0087] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0088] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0089] Furthermore, the use of terms such as "first," "second," etc., in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. In the description of this application, "multiple sets" means at least two sets, such as two sets, three sets, etc., unless otherwise explicitly specified.

[0090] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0091] Furthermore, the technical solutions of the various embodiments of this application can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this application.

[0092] The calibration method for the two-dimensional Doppler velocimeter provided in this application can be applied to, for example... Figure 1 In the application environment shown, terminal 102 communicates with server 104 via a network. Terminal 102 may include, but is not limited to, various personal computers, laptops, smartphones, tablets, and portable wearable devices. Server 104 may be a server corresponding to various portal websites or work system backends.

[0093] This application provides a calibration method for a two-dimensional Doppler velocimeter, such as... Figure 2 As shown, in one embodiment, the method is applied to Figure 1 Taking the terminal in the example, the explanation includes:

[0094] Step 202: Obtain the beam wavelength, Doppler frequency shift of the first beam, Doppler frequency shift of the second beam, design tilt angle of the first beam, and design tilt angle of the second beam of the two-dimensional laser Doppler velocimeter. Obtain the forward error velocity and upward error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system, and obtain the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system.

[0095] Specifically:

[0096] A two-dimensional laser Doppler velocimeter emits two beams, namely a first beam and a second beam. By acquiring the beam wavelengths, the Doppler frequency shift of the first beam, and the Doppler frequency shift of the second beam, the velocities in the directions of the first and second beams can be obtained.

[0097]

[0098]

[0099] In the formula, υ1 is the velocity along the direction of the first beam, υ2 is the velocity along the direction of the second beam, and λ is the beam wavelength of the two-dimensional laser Doppler velocimeter. The Doppler frequency shift measured for the first beam and The Doppler frequency shift measured for the second beam.

[0100] In a combined navigation system consisting of an inertial navigation system and a laser Doppler velocimeter, the laser Doppler velocimeter measures the velocity in its own coordinate system.

[0101] The actual tilt angles of the first and second beams are obtained. Based on these actual tilt angles, the velocities along the first and second beams, and the velocities along the second beams, the true forward and upward velocities of the two-dimensional laser Doppler velocimeter are obtained. Finally, the true velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system is also obtained.

[0102]

[0103] The velocities υ1 and υ2 of the two beam directions and the corresponding beam tilt angles θ1 and θ2, and the forward velocity υ of the two-dimensional laser Doppler velocimeter. y With the upward velocity υ z The following relationship exists:

[0104] υ y cosθ1+υ z sinθ1=υ1 (1)

[0105] υ y cosθ2+υ z sinθ2=υ2 (2)

[0106] Solving equations (1) and (2) simultaneously yields the forward velocity υ of the two-dimensional laser Doppler velocimeter. y With the upward velocity υ z Its expression is as follows:

[0107]

[0108]

[0109] Rewriting equations (3) and (4) yields:

[0110] υ y =K1υ2-K2υ1 (5)

[0111] υ z =K3υ1-K4υ2 (6)

[0112] in:

[0113]

[0114]

[0115]

[0116]

[0117] In the formula, υ represents the true velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system. y υ represents the true forward velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system. z θ1 represents the actual celestial velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system, K1, K2, K3, and K4 are scaling factors, θ1 is the actual tilt angle of the first beam of the two-dimensional laser Doppler velocimeter, and θ2 is the actual tilt angle of the second beam of the two-dimensional laser Doppler velocimeter.

[0118] In practical applications, the actual tilt angles θ1 and θ2 of the beam are not equal to the design values, but deviate from the design values. Therefore, the forward and upward velocities of the carrier obtained based on the tilt angle design values ​​will deviate from the actual values.

[0119] Taking tilt angle error into account, the design tilt angles of the first beam and the second beam are obtained. Based on the design tilt angles of the first beam and the second beam, the velocities in the directions of the first and second beams, the forward and upward error velocities of the two-dimensional laser Doppler velocimeter in its own coordinate system are obtained, as well as the overall error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system.

[0120]

[0121]

[0122]

[0123]

[0124]

[0125]

[0126]

[0127] In the formula, This represents the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system. The forward error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system. The celestial error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system. δK i The scaling factor error is caused by the deviation between the design tilt angle and the actual tilt angle. The design tilt angle of the first beam of the two-dimensional laser Doppler velocimeter. The tilt angle is the design angle of the second beam of the two-dimensional laser Doppler velocimeter.

[0128] Step 204: Transform the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system to the carrier coordinate system to obtain the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system; transform the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system to the navigation coordinate system to obtain the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system.

[0129] Specifically:

[0130] In practical applications, the coordinate system of the laser Doppler velocimeter is rarely aligned with the coordinate system of the inertial navigation system, resulting in an installation angle error. Similar to the scaling factor error, the installation angle error significantly affects the accuracy of the measurements taken by the two-dimensional laser Doppler velocimeter, and consequently, the accuracy of the integrated navigation system. Therefore, it is necessary to consider the installation angle error of the laser Doppler velocimeter.

[0131] The projection of the error velocity of a two-dimensional laser Doppler velocimeter in the carrier coordinate system can be expressed as:

[0132]

[0133] in,

[0134]

[0135] φ m =[φ mx φ my φ mz ] T

[0136] In the formula, Let I3 be the projection of the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system, where I3 represents the third-order identity matrix, m represents the coordinate system in which the two-dimensional laser Doppler velocimeter is located, b represents the carrier coordinate system, and φ is the projection of the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system. m φ represents the installation error angle between the coordinate system of the two-dimensional laser Doppler velocimeter and the coordinate system of the carrier. mx For the pitch installation error angle, φ my For the roll installation error angle, φ mz The heading installation error angle is represented by ×, which indicates the matrix cross product. This represents the attitude transformation matrix from the m-frame to the b-frame.

[0137] The error velocity of a two-dimensional laser Doppler velocimeter in the navigation coordinate system can be expressed as:

[0138]

[0139] in,

[0140]

[0141] In the formula, Let φ represent the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, where n represents the navigation coordinate system and φ represents the attitude error angle of the inertial navigation system. This represents the attitude transformation matrix from the b-system to the n-system.

[0142] Step 206: Construct the error model of the strapdown inertial navigation system; based on the error parameters of the two-dimensional laser Doppler velocimeter and the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, obtain the error model of the two-dimensional laser Doppler velocimeter.

[0143] Specifically:

[0144] Since the velocity of a strapdown inertial navigation system can be expressed as,

[0145]

[0146] The velocity of a two-dimensional laser Doppler velocimeter in the n-frame can be expressed as:

[0147]

[0148] Furthermore, combining equations (11) and (19) yields the actual velocity expression for a two-dimensional laser Doppler velocimeter in the navigation coordinate system used in practical applications.

[0149]

[0150] in,

[0151] δK=[δK1δK2δK3δK4] T

[0152]

[0153]

[0154]

[0155]

[0156] Therefore, equation (20) is rewritten as follows:

[0157]

[0158] The velocity error model of the two-dimensional laser Doppler velocimeter in the navigation coordinate system is as follows:

[0159]

[0160] In the formula, The output speed of the strapdown inertial navigation system. For the speed error of the strapdown inertial navigation system, This represents the actual velocity projection of the laser Doppler velocimeter in the navigation coordinate system, i.e., the n-frame. This represents the actual velocity projection of the laser Doppler velocimeter in the carrier coordinate system, i.e., the b-frame. This is the error model for a two-dimensional laser Doppler velocimeter.

[0161] In a combined navigation system based on a two-dimensional laser Doppler velocimeter and a strapdown inertial navigation system, the error model of the strapdown inertial navigation system is established as follows:

[0162] Attitude error equation:

[0163]

[0164] Velocity error equation:

[0165]

[0166] Position error equation:

[0167]

[0168]

[0169]

[0170] Gyroscope error equation:

[0171]

[0172] Add table error equation:

[0173]

[0174] in:

[0175]

[0176]

[0177]

[0178] And:

[0179] υ n =[υ E υ N υ U ] T

[0180] δυ n =[δυ E δυ N δυ U ] T

[0181] In the formula, f n υ represents the projection of the specific force obtained from the accelerometer output into the navigation coordinate system. n For the speed information of the strapdown inertial navigation system, υ E υN υ U δυ represents the eastward velocity, northward velocity, and upward velocity, respectively. n Let P represent the velocity error of the strapdown inertial navigation system, where L, λ, and h represent Earth's latitude, longitude, and altitude, respectively. P = [Lλh] T The position information of the strapdown inertial navigation system is represented by δP = [δLδλδh]. T R represents the position error of the strapdown inertial navigation system. M and R N ω represents the radii of curvature of the Earth's meridian and geoid at the location of the carrier, respectively. ie It represents the angular velocity of Earth's rotation.

[0182] Step 208: Based on the error model of the two-dimensional laser Doppler velocimeter and the error model of the strapdown inertial navigation system, a Kalman filter is constructed. Using the Global Positioning System as the reference, and taking the velocity error and position error of the strapdown inertial navigation system and the velocity error of the two-dimensional laser Doppler velocimeter in the navigation coordinate system as observations, the state vector of the combined navigation system composed of the two-dimensional laser Doppler velocimeter and the strapdown inertial navigation system is estimated, and the two-dimensional laser Doppler velocimeter is calibrated based on the estimation results.

[0183] Specifically:

[0184] The three installation error angles, four scaling factor errors, inertial navigation attitude error, velocity error, position error, gyroscope measurement error, and accelerometer measurement error of the two-dimensional laser Doppler velocimeter are collectively used to construct the state vector of the integrated navigation system. The state vector in the Kalman filter model is 22-dimensional, i.e.:

[0185]

[0186] In the formula, X(t) is the state vector of the integrated navigation system. For the attitude error of the inertial navigation system, δυ n δυ is the inertial navigation velocity error (written as δυ in equation (20)), and δP is the inertial navigation position error. For gyroscope measurement error, For accelerometer measurement error, φ mx φ my φ mz The three installation error angles of the two-dimensional laser Doppler velocimeter are pitch installation error angle, roll installation error angle and heading installation error angle, and δK1, δK2, δK3 and δK4 are four scaling factor errors.

[0187] Using a Kalman filter for state estimation, the state equation is expressed as:

[0188]

[0189] In the formula, F(t) represents the system state transition matrix, G(t) represents the system noise matrix, and w(t) represents the system noise vector;

[0190] The system state transition matrix F(t) is expressed as:

[0191]

[0192] in,

[0193]

[0194]

[0195]

[0196]

[0197]

[0198]

[0199] The system noise matrix is ​​represented as:

[0200]

[0201] The system noise vector is represented as:

[0202]

[0203] In the formula, ε wi This indicates the noise of the gyroscope. This indicates the noise level of the accelerometer.

[0204] Using the output velocity and position of the Global Positioning System (GPS) as a reference, and the velocity and position errors of the strapdown inertial navigation system (SINS) and the velocity error of the two-dimensional laser Doppler velocimeter in the navigation coordinate system as observations, the state vector is estimated. The measurement equation in the Kalman filter is expressed as:

[0205]

[0206] In the formula, υ SINS P is the output speed of the strapdown inertial navigation system. SINS For the output position of the strapdown inertial navigation system, υ GPS The output velocity information provided by the Global Positioning System, p GPS The location information provided by the Global Positioning System (GPS) is represented by z(t), where z(t) is the filtered observation, H(t) is the measurement matrix of the filter, and V(t) is the measurement noise vector; υSINS -υ GPS For the velocity error of the strapdown inertial navigation system, P SINS -P GPS For the position error of the strapdown inertial navigation system, The velocity error of the two-dimensional laser Doppler velocimeter in the navigation coordinate system;

[0207] The measurement matrix H(t) is expressed as:

[0208]

[0209] in,

[0210]

[0211] In the formula, This represents the celestial velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system. This represents the forward velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system. This represents the rightward velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system.

[0212] In this step, a Kalman filter is constructed. Based on the velocity of the 2D laser Doppler velocimeter, four scaling factors are set. The errors of the four scaling factors and the three installation error angles of the 2D laser Doppler velocimeter are used as part of the state variables of the Kalman filter. The position difference and velocity difference between the GPS and the inertial navigation system are used as filtering observations. In addition, the velocity difference between the GPS and the 2D laser Doppler velocimeter is also used as a filtering observation. The state vector of the combined navigation system consisting of the 2D laser Doppler velocimeter and the strapdown inertial navigation system is estimated. Based on the filtered state vector, the relevant terms of the 2D laser Doppler velocimeter and the strapdown inertial navigation system, i.e., the filtered state variables, are fed back for correction. Finally, the positioning is calibrated based on the corrected positioning results.

[0213] In this embodiment, as Figure 3 As shown, IMU represents Inertial Measurement Unit, LDV represents Two-Dimensional Laser Doppler Velocimetry, and X... b Y b Z b The X-axis represents the coordinate system of the carrier in which the inertial measurement unit is located. m Y m Z m This indicates the coordinate system of the two-dimensional laser Doppler velocimeter. It should also be noted that SINS stands for Strapdown Inertial Navigation System.

[0214] When using a strapdown inertial navigation system, the inertial measurement unit (IMU) and the 2D laser Doppler velocimeter (DTV) need to be properly installed. Specifically, the IMU should be installed in the center of the vehicle's rear axle, and the DTV should be installed in a suitable position on the side or rear of the vehicle, ensuring that the DTV's beam effectively hits the ground and obtains a strong signal to acquire real-time, accurate vehicle velocity information. Before using the strapdown inertial navigation system, the IMU needs to be calibrated to obtain the gyroscope and accelerometer calibration errors, installation error angles, and zero bias. Before entering the formal navigation process, system initialization is also required to obtain initial attitude, velocity, and position, including acquiring the vehicle's initial position and velocity information and completing initial alignment.

[0215] The calibration method for the aforementioned two-dimensional Doppler velocimeter derives the velocity expressions of the two-dimensional laser Doppler velocimeter in its own coordinate system in the forward and upward directions based on the two outputs of the velocimeter. It also analyzes the error terms of the two-dimensional laser Doppler velocimeter during integrated navigation (including four scaling factor errors δK1, δK2, δK3, and δK4, and three installation error angles φ). mx φ my φ mzThis paper integrates a two-dimensional laser Doppler velocimeter, a global positioning system (GPS), and an inertial navigation system. It analyzes the output velocity of the two-dimensional laser Doppler velocimeter in different coordinate systems and the error terms causing the measurement error. The error terms are used as the state vector, and Kalman filtering is used to estimate the error terms. High-precision velocity and position information from the GPS are used as part of the filtering observations to more accurately and quickly calibrate the error terms of the two-dimensional laser Doppler velocimeter. The error terms of the two-dimensional laser Doppler velocimeter are then used as the state vector. Kalman filtering is employed to estimate the error terms, and high-precision velocity and position information from the GPS are used as part of the filtering observations to more accurately and quickly calibrate the error terms of the two-dimensional laser Doppler velocimeter. This invention enables precise calibration of a two-dimensional laser Doppler velocimeter. The precisely calibrated 2D laser Doppler velocimeter provides richer and more accurate velocity information for integrated navigation systems, including precise velocities in both the forward and upward directions, especially the more precise upward velocity information. This allows the integrated navigation system to obtain more accurate altitude information, giving the 2D laser Doppler velocimeter a significant advantage in altitude measurement compared to one-dimensional laser Doppler velocimeters and odometers. In existing technologies, 2D laser Doppler velocimeters are designed for a structure with two beams emitting mirror images. During online calibration, the beam deviation angle of the velocimeter needs to be estimated. When the two beams are no longer emitted mirror images, the beam deviation angle of one beam may be too large, leading to inaccurate estimation and poor calibration results. This invention, however, is not limited by the emission direction of the two beams in the 2D laser Doppler velocimeter, resulting in accurate calibration results.

[0216] It should be understood that, although Figure 2 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 2 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0217] This application also provides a calibration device for a two-dimensional Doppler velocimeter, such as Figure 4As shown, in one embodiment, it includes: an acquisition module 402, a transfer module 404, a modeling module 406, and a calibration module 408, wherein:

[0218] The acquisition module 402 is used to acquire the beam wavelength, Doppler frequency shift of the first beam, Doppler frequency shift of the second beam, design tilt angle of the first beam and design tilt angle of the second beam of the two-dimensional laser Doppler velocimeter, to obtain the forward error velocity and upward error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system, and to obtain the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system.

[0219] The conversion module 404 is used to convert the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system to the carrier coordinate system, so as to obtain the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system; and to convert the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system to the navigation coordinate system, so as to obtain the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system.

[0220] Modeling module 406 is used to construct the error model of the strapdown inertial navigation system; based on the error parameters of the two-dimensional laser Doppler velocimeter and the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, the error model of the two-dimensional laser Doppler velocimeter is obtained.

[0221] The calibration module 408 is used to construct a Kalman filter based on the error model of the two-dimensional laser Doppler velocimeter and the error model of the strapdown inertial navigation system. Using the Global Positioning System as a reference, and taking the velocity error and position error of the strapdown inertial navigation system and the velocity error of the two-dimensional laser Doppler velocimeter in the navigation coordinate system as observations, the module estimates the state vector of the combined navigation system composed of the two-dimensional laser Doppler velocimeter and the strapdown inertial navigation system, and calibrates the two-dimensional laser Doppler velocimeter based on the estimation results.

[0222] In one embodiment, the acquisition module 402 is further configured to acquire the beam wavelength of the two-dimensional laser Doppler velocimeter, the Doppler frequency shift of the first beam, the Doppler frequency shift of the second beam, the design tilt angle of the first beam, and the design tilt angle of the second beam, to obtain the forward error velocity and the upward error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system, and to obtain the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system, including:

[0223] By acquiring the beam wavelength, Doppler frequency shift of the first beam, and Doppler frequency shift of the second beam from a two-dimensional laser Doppler velocimeter, the velocities in the first beam direction and the second beam direction can be obtained:

[0224]

[0225]

[0226] In the formula, υ1 is the velocity along the direction of the first beam, υ2 is the velocity along the direction of the second beam, and λ is the beam wavelength of the two-dimensional laser Doppler velocimeter. The Doppler frequency shift measured for the first beam and The Doppler frequency shift measured for the second beam;

[0227] The design tilt angles of the first and second beams are obtained. Based on these angles, the velocities along the first and second beams, and the velocities along the second beams, the forward and upward error velocities of the two-dimensional laser Doppler velocimeter in its own coordinate system are calculated. Finally, the overall error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system is also obtained.

[0228]

[0229]

[0230]

[0231]

[0232]

[0233]

[0234]

[0235] In the formula, This represents the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system. The forward error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system. The celestial error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system. δK i The scaling factor error is caused by the deviation between the design tilt angle and the actual tilt angle. The design tilt angle of the first beam of the two-dimensional laser Doppler velocimeter. The tilt angle is the design angle of the second beam of the two-dimensional laser Doppler velocimeter.

[0236] In one embodiment, the conversion module 404 is further configured to convert the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system to the carrier coordinate system, thereby obtaining the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system, including:

[0237]

[0238]

[0239] φ m =[φ mx φ my φ mz ] T

[0240] In the formula, Let I3 represent the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system, m represent the coordinate system of the two-dimensional laser Doppler velocimeter, b represent the carrier coordinate system, and φ represent the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system. m φ represents the installation error angle between the coordinate system of the two-dimensional laser Doppler velocimeter and the coordinate system of the carrier. mx For the pitch installation error angle, φ my For the roll installation error angle, φ mz The heading installation error angle is represented by ×, which indicates the matrix cross product. This represents the attitude transformation matrix from the m-frame to the b-frame.

[0241] In one embodiment, the conversion module 404 is further configured to convert the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system to the navigation coordinate system, thereby obtaining the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, including:

[0242]

[0243]

[0244] In the formula, Let φ represent the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, where n represents the navigation coordinate system and φ represents the attitude error angle of the inertial navigation system. This represents the attitude transformation matrix from the b-system to the n-system.

[0245] In one embodiment, the modeling module 406 is further configured to obtain an error model of the two-dimensional laser Doppler velocimeter based on the error parameters of the two-dimensional laser Doppler velocimeter and the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, including:

[0246] because:

[0247]

[0248]

[0249] δK=[δK1δK2δK3δK4] T

[0250] therefore:

[0251]

[0252]

[0253] In the formula, This represents the true velocity of the laser Doppler velocimeter in the n-frame. This represents the actual velocity of the laser Doppler velocimeter in the b-frame. This is the error model for a two-dimensional laser Doppler velocimeter.

[0254] In one embodiment, the modeling module 406 is further configured to construct an error model for the strapdown inertial navigation system, including:

[0255]

[0256]

[0257]

[0258]

[0259]

[0260]

[0261]

[0262] in:

[0263] υ n =[υ E υ N υ U ] T

[0264] δυ n =[δυ E δυ N δυ U ] T

[0265]

[0266]

[0267]

[0268] In the formula, f n υ represents the projection of the specific force obtained from the accelerometer output into the navigation coordinate system. n For the speed information of the strapdown inertial navigation system, υ E υ N υ Uδυ represents the eastward velocity, northward velocity, and upward velocity, respectively. n R represents the velocity error of the strapdown inertial navigation system, where L, λ, and h represent Earth's latitude, longitude, and altitude, respectively. M and R N ω represents the radii of curvature of the Earth's meridian and geoid at the location of the carrier, respectively. ie It represents the angular velocity of Earth's rotation.

[0269] In one embodiment, the calibration module 408 is further configured to construct a Kalman filter based on the error model of the two-dimensional laser Doppler velocimeter and the error model of the strapdown inertial navigation system, and to estimate the state vector of the combined navigation system consisting of the two-dimensional laser Doppler velocimeter and the strapdown inertial navigation system, including:

[0270] The three installation error angles, four scaling factor errors, inertial navigation attitude error, velocity error, position error, gyroscope measurement error, and accelerometer measurement error of the two-dimensional laser Doppler velocimeter are collectively used to construct the state vector of the integrated navigation system:

[0271]

[0272] In the formula, X(t) is the state vector of the integrated navigation system. For inertial navigation attitude error, δυ n δP represents the velocity error, and δP represents the position error. For gyroscope measurement error, For accelerometer measurement error, φ mx φ my φ mz These are the three installation error angles of the two-dimensional laser Doppler velocimeter, and δK1, δK2, δK3, and δK4 are the four scaling factor errors.

[0273] Using the output velocity and position of the Global Positioning System (GPS) as a reference, and the velocity and position errors of the strapdown inertial navigation system (SINS) and the velocity error of the two-dimensional laser Doppler velocimeter in the navigation coordinate system as observations, the state vector is estimated:

[0274]

[0275] In the formula, υ SINS P is the output speed of the strapdown inertial navigation system. SINS For the output position of the strapdown inertial navigation system, υ GPS p represents the output speed of the Global Positioning System. GPS Let z(t) be the position of the Global Positioning System, z(t) be the filtered observation, H(t) be the measurement matrix of the filter, and V(t) be the measurement noise vector.

[0276] Specific limitations regarding the calibration device for the two-dimensional Doppler velocimeter can be found in the above description of the calibration method for the two-dimensional Doppler velocimeter, and will not be repeated here. Each module in the aforementioned device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0277] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 5 As shown, the computer device includes a processor, memory, network interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The network interface is used to communicate with external terminals via a network connection. When the computer program is executed by the processor, it implements a calibration method for a two-dimensional Doppler velocimeter. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0278] Those skilled in the art will understand that Figure 5 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0279] In one embodiment, a computer device is provided, including a memory and a processor, the memory storing a computer program, the processor executing the computer program to implement the steps of the method described above.

[0280] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described above.

[0281] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0282] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0283] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A calibration method for a two-dimensional Doppler velocimeter, characterized in that, include: The beam wavelength, Doppler frequency shift of the first beam, Doppler frequency shift of the second beam, design tilt angle of the first beam, and design tilt angle of the second beam of the two-dimensional laser Doppler velocimeter are obtained. The forward error velocity and upward error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system are obtained, and the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system is also obtained. The error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system is transformed to the carrier coordinate system to obtain the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system; the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system is transformed to the navigation coordinate system to obtain the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system. An error model for a strapdown inertial navigation system is constructed. Based on the error parameters of a two-dimensional laser Doppler velocimeter and the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, the error model of the two-dimensional laser Doppler velocimeter is obtained. Based on the error models of the two-dimensional laser Doppler velocimeter and the strapdown inertial navigation system, a Kalman filter is constructed. Using the Global Positioning System as the reference, and taking the velocity error and position error of the strapdown inertial navigation system and the velocity error of the two-dimensional laser Doppler velocimeter in the navigation coordinate system as the observations, the state vector of the combined navigation system composed of the two-dimensional laser Doppler velocimeter and the strapdown inertial navigation system is estimated, and the two-dimensional laser Doppler velocimeter is calibrated based on the estimation results. include: The three installation error angles, four scaling factor errors, inertial navigation attitude error, velocity error, position error, gyroscope measurement error, and accelerometer measurement error of the two-dimensional laser Doppler velocimeter are collectively used to construct the state vector of the integrated navigation system: In the formula, This is the state vector of the integrated navigation system. For inertial navigation attitude error, For speed error, For positional error, For gyroscope measurement error, To account for accelerometer measurement error, , , These are the three installation error angles of a two-dimensional laser Doppler velocimeter. , , , The error consists of four scaling factors; Using the output velocity and position of the Global Positioning System (GPS) as a reference, and the velocity and position errors of the strapdown inertial navigation system (SINS) and the velocity error of the two-dimensional laser Doppler velocimeter in the navigation coordinate system as observations, the state vector is estimated: In the formula, The output speed of the strapdown inertial navigation system. This is the output position of the strapdown inertial navigation system. For the output speed of the Global Positioning System, For the location of the Global Positioning System, For filtered observations, This is the measurement matrix of the filter. This is the measurement noise vector.

2. The method according to claim 1, characterized in that, By obtaining the beam wavelength, Doppler frequency shift of the first beam, Doppler frequency shift of the second beam, design tilt angle of the first beam, and design tilt angle of the second beam of the two-dimensional laser Doppler velocimeter, the forward error velocity and upward error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system are obtained. The error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system includes: By acquiring the beam wavelength, Doppler frequency shift of the first beam, and Doppler frequency shift of the second beam from a two-dimensional laser Doppler velocimeter, the velocities in the first beam direction and the second beam direction can be obtained: In the formula, The velocity along the direction of the first beam, The velocity along the direction of the second beam. The wavelength of the laser beam in a two-dimensional laser Doppler velocimeter. The Doppler frequency shift measured for the first beam and The Doppler frequency shift measured for the second beam; The design tilt angles of the first and second beams are obtained. Based on these angles, the velocities along the first and second beams, and the velocities along the second beams, the forward and upward error velocities of the two-dimensional laser Doppler velocimeter in its own coordinate system are calculated. Finally, the overall error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system is also obtained. In the formula, This represents the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system. The forward error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system. The celestial error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system. , The scaling factor error is caused by the deviation between the design tilt angle and the actual tilt angle. The design tilt angle of the first beam of the two-dimensional laser Doppler velocimeter. The tilt angle is the design angle of the second beam of the two-dimensional laser Doppler velocimeter.

3. The method according to claim 2, characterized in that, Transforming the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system to the carrier coordinate system, we obtain the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system, which includes: In the formula, The error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system. Represents a third-order identity matrix. m This represents the coordinate system in which the two-dimensional laser Doppler velocimeter is located. b Indicates the carrier coordinate system. This represents the installation error angle between the coordinate system of the two-dimensional laser Doppler velocimeter and the coordinate system of the carrier. For pitch installation error angle, For the roll installation error angle, For the heading installation error angle, Represents the matrix cross product. express m Tie b The attitude transformation matrix of the system.

4. The method according to claim 3, characterized in that, Transforming the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system to the navigation coordinate system yields the following error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system: In the formula, The error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system. n Indicates the navigation coordinate system. This represents the attitude error angle of the inertial navigation system. express b Tie n The attitude transformation matrix of the system.

5. The method according to claim 4, characterized in that, Based on the error parameters of the two-dimensional laser Doppler velocimeter and its error velocity in the navigation coordinate system, the error model of the two-dimensional laser Doppler velocimeter is obtained, including: because: therefore: In the formula, Indicates that the laser Doppler velocimeter is in n The actual speed in the system, Indicates that the laser Doppler velocimeter is in b The actual speed in the system, This is the error model for a two-dimensional laser Doppler velocimeter.

6. The method according to any one of claims 1 to 5, characterized in that, The error model for constructing a strapdown inertial navigation system includes: in: In the formula, This represents the projection of the specific force obtained from the accelerometer output into the navigation coordinate system. For the speed information of the strapdown inertial navigation system, , , These represent the eastward velocity, the northward velocity, and the upward velocity, respectively. This indicates the speed error of the strapdown inertial navigation system. L , , h These represent Earth's latitude, longitude, and altitude, respectively. and These represent the radii of curvature of the Earth's meridian and circumference at the location of the carrier, respectively. It represents the angular velocity of Earth's rotation.

7. A calibration device for a two-dimensional Doppler velocimeter, characterized in that, The calibration method for the two-dimensional Doppler velocimeter according to any one of claims 1 to 6 includes: The acquisition module is used to acquire the beam wavelength, Doppler frequency shift of the first beam, Doppler frequency shift of the second beam, design tilt angle of the first beam, and design tilt angle of the second beam of the two-dimensional laser Doppler velocimeter, to obtain the forward error velocity and upward error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system, and to obtain the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system. The conversion module is used to convert the error velocity of the two-dimensional laser Doppler velocimeter in its own coordinate system to the carrier coordinate system, thereby obtaining the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system; and to convert the error velocity of the two-dimensional laser Doppler velocimeter in the carrier coordinate system to the navigation coordinate system, thereby obtaining the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system. The modeling module is used to construct the error model of the strapdown inertial navigation system; based on the error parameters of the two-dimensional laser Doppler velocimeter and the error velocity of the two-dimensional laser Doppler velocimeter in the navigation coordinate system, the error model of the two-dimensional laser Doppler velocimeter is obtained. The calibration module is used to construct a Kalman filter based on the error models of the two-dimensional laser Doppler velocimeter and the strapdown inertial navigation system. Using the Global Positioning System as a reference, and taking the velocity error and position error of the strapdown inertial navigation system and the velocity error of the two-dimensional laser Doppler velocimeter in the navigation coordinate system as observations, the module estimates the state vector of the combined navigation system composed of the two-dimensional laser Doppler velocimeter and the strapdown inertial navigation system, and calibrates the two-dimensional laser Doppler velocimeter based on the estimation results.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

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