A method for calibrating inertial navigation of mobile platform

Abstract

The present invention provides a mobile platform inertial navigation calibration method, which belongs to the field of measurement and control and radar technology; the specific steps are to first complete the photoelectric axis consistency calibration of the measurement and control antenna, then build the optical calibration environment of the mobile measurement and control platform, align the low-light television with the far-field optical target, measure the high-precision position information of the optical target and the measurement and control antenna, and correct the inertial navigation output attitude through the error of the electric axis pointing and the initial calibration of the inertial navigation, so that the inertial navigation output attitude information is consistent with the vehicle attitude, and the output position information coincides with the measurement and control antenna phase center, completing the high-precision calibration of the inertial navigation attitude and position. The present invention can complete the high-precision inertial navigation calibration of the vehicle-carrying mobile measurement and control platform with only one optical target, and reduces the number of calibration reference targets and environmental requirements, can be executed around the clock, and has universal applicability.

Description

Technical Field

[0001] The invention relates to the fields of measurement and control and radar, and in particular to a mobile platform inertial navigation calibration method. Background Art

[0002] In the field of mobile measurement and control, the system is required to complete the target measurement and control task during the maneuvering process. On the one hand, the antenna servo control and target tracking system are required to have the ability to isolate the vehicle and ship from the rocking of the vehicle and the ship, and to be able to achieve stable target tracking when the platform is maneuvering. On the other hand, it is necessary to have high-precision attitude and positioning capabilities to obtain the position and attitude of the vehicle / ship in real time, and correct the target pointing deviation caused by the maneuvering of the vehicle / ship. The mobile platform generally obtains the platform position and attitude information in real time through high-precision inertial navigation. After the inertial navigation is installed, the installation error is eliminated through calibration, so that the position and attitude information output by the inertial navigation is consistent with the measurement and control antenna. The measurement and control technology for vehicle maneuvers is a new technology that has begun to develop in recent years. At present, there are few studies on the calibration methods of vehicle-mounted mobile platforms. The inertial navigation calibration method of the vehicle-mounted mobile platform can refer to the calibration method of the ship-mounted platform. The conventional solution is to use multi-star positioning to determine the transfer matrix between the inertial navigation coordinate system and the ship coordinate system, and to correct the inertial navigation output data. The main problems with this method are:

[0003] 1) Calibration is limited by time and weather. Since it needs to calibrate the star mark, it can generally only be done at night when the weather is clear;

[0004] 2) A large number of targets are required, generally more than 3 stars are needed to obtain an accurate transfer matrix;

[0005] 3) The calibration of star marks is affected by the atmospheric environment and is prone to large errors. Summary of the invention

[0006] In view of this, the present invention provides a mobile platform inertial navigation calibration method. The design can be used for inertial navigation calibration of a mobile measurement and control platform on a vehicle, has low requirements on the calibration environment, can be performed around the clock, and only requires one optical target to complete the inertial navigation calibration.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A mobile platform inertial navigation calibration method specifically includes the following methods:

[0009] Step 1: Install the low-light TV and make its lens face the direction of the antenna wave to complete the photoelectric axis consistency calibration;

[0010] Step 2: Place the vehicle on a hard surface, turn off the engine and keep it stationary. First, roughly level the large plate. Then, use the vehicle's adjustment and leveling mechanism to make the vehicle chassis level, that is, the vehicle coordinate system horizontal plane. Horizontal plane with navigation coordinate system Parallel, the horizontal accuracy of the disk after adjustment is better than the preset accuracy ;

[0011] Step 3: Obtain the coordinates of the center of the telemetry antenna on the vehicle in the ENU coordinate system through geodetic measurement and calculation of the vehicle structure parameters. ;

[0012] Step 4: Use the image level to fine-tune the level of the plate to make the plate level meet the preset accuracy. ;

[0013] Step 5: Turn on the inertial navigation system for rough alignment and fine alignment to obtain the attitude matrix of the inertial navigation coordinate system and the navigation coordinate system, that is, the inertial navigation heading angle , pitch angle and roll angle , and the pitch angle and roll angle data are approximated as ,Right now ;

[0014] Step 6: Place the optical target in the far field of the antenna, align the measurement and control antenna with the direction of the optical target through the low-light television, and measure the coordinates of the center of the optical target in the ENU coordinate system. ; Read the value of the antenna horizontal encoder , that is, the angle between the pointing direction of the measurement and control antenna and the azimuth of the vehicle coordinate system 0°;

[0015] Step 7, correct the attitude matrix output by the inertial navigation system so that the inertial navigation coordinate system coincides with the vehicle coordinate system;

[0016] Step 8, measure the three-dimensional coordinates of the phase center of the measurement and control antenna and the inertial navigation center, correct the inertial navigation position information, and make the inertial navigation output position center coincide with the phase center of the measurement and control antenna.

[0017] Furthermore, the mobile platform used includes a carrier vehicle, a cabin, a measurement and control antenna, measurement and control equipment, an inertial navigation system, a low-light-level television and an optical target; the carrier vehicle includes a tractor and a semi-trailer, the semi-trailer is towed by the tractor, and a leveling mechanism is installed around the chassis of the semi-trailer; the cabin is installed on the semi-trailer, and includes an equipment cabin and an antenna cabin; wherein the measurement and control antenna is installed in the antenna cabin and fixedly connected to the chassis of the semi-trailer; the inertial navigation system is installed on the inertial navigation installation platform on the side of the measurement and control antenna sleeve; the low-light-level television is installed behind the measurement and control antenna, with the lens facing the direction of the antenna wave; the measurement and control equipment is installed in the equipment cabin; the optical target is located in the far-field area outside the carrier vehicle.

[0018] Furthermore, the ENU coordinate system in step 3 is consistent with the navigation coordinate system coincide.

[0019] Furthermore, the specific process of step 4 is as follows:

[0020] Step 401, placing an image level on the azimuth turntable platform of the measurement and control antenna, with the knob end of the image level facing the azimuth rotation center, to fix the antenna elevation angle;

[0021] Step 402, starting from 0°, rotate the antenna azimuth and read the image level reading every 15° and azimuth encoder readings Once, until 345°; sort out the data and find out the maximum tilt direction of the market and maximum tilt ;

[0022] Step 403, calibrate the levelness of the plate by adjusting the leveling mechanism, and then repeat step 402 until the maximum levelness of the plate meets the preset accuracy. .

[0023] Furthermore, the specific process of step 7 is as follows:

[0024] First, correct the pitch and roll angles output by the inertial navigation: ,Right now , Secondly, the corrected inertial navigation output heading angle is ;in, The vector of the line connecting the phase center of the measurement and control antenna and the optical target in the horizontal plane of the navigation coordinate system The angle between the projection and the navigation coordinate system azimuth 0°,

[0025] ,

[0026] in, , abs means absolute value, and atan means inverse tangent.

[0027] Furthermore, the specific process of the photoelectric axis consistency calibration in step 1 is as follows:

[0028] Step 101, placing a calibration antenna and an optical target in a far field area;

[0029] Step 102, the relative position between the optical target and the calibration antenna is mirror-symmetrical to the relative position between the low-light-level television and the measurement and control antenna center;

[0030] Step 103, the calibration antenna transmits a calibration signal to align the electrical axis center of the measurement and control antenna with the calibration antenna;

[0031] Step 104, adjusting the low-light television so that the optical axis is aligned with the optical target, and at this time, the electric axis and the optical axis are parallel to each other;

[0032] The error of the above photoelectric axis consistency is: , in arc seconds, where Indicates the optical target reading error, which is the smallest scale unit of the dial. Indicates the distance between the low light TV and the optical target;

[0033] Choose the right distance , so that the photoelectric axis consistency error < , is the inertial navigation accuracy, in arc seconds; the calibration antenna should meet the far-field condition, that is, the distance between the calibration antenna and the measurement and control antenna is ,in, is the diameter of the telemetry antenna, The wavelength of the calibration signal carrier.

[0034] Furthermore, the preset precision of the large disk level rough adjustment Equal to the leveling accuracy of the leveling mechanism, fine adjustment accuracy Less than the inertial navigation accuracy The rough adjustment process of the large plate level is automatic leveling or manual leveling through the leveling mechanism.

[0035] Furthermore, the measurement of the position of the vehicle's measurement and control antenna and optical target adopts high-precision measurement methods such as differential GPS or total station, so that the azimuth error caused by the positioning error is lower than the inertial navigation heading accuracy. , that is, the position error ,in, The optical target and the measurement and control antenna are in the horizontal plane of the navigation coordinate system. projection distance.

[0036] The beneficial effects of the present invention are mainly as follows:

[0037] 1. The present invention provides an inertial navigation calibration method for a mobile platform, which solves the difficulty of inertial navigation calibration under vehicle maneuvering conditions and lays a foundation for realizing mobile measurement and control.

[0038] 2. The present invention can be implemented around the clock and is not affected by the climate environment.

[0039] 3. The present invention only requires one optical target as a reference, which reduces the constraints on the reference target conditions. The method can also be used for star calibration, and only one star is needed to complete the calibration.

[0040] 4. The present invention obtains high-precision pointing information of the target through high-precision position measurement, thereby achieving higher inertial navigation calibration accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 This is a schematic diagram of the inertial navigation calibration process principle of the mobile platform.

[0043] Figure 2 This is a schematic diagram of the principle of photoelectric axis consistency calibration.

[0044] Figure 3 It is a schematic diagram of the appearance of the mobile measurement and control platform structure collection.

[0045] Figure 4 This is a schematic diagram of the appearance of the mobile measurement and control platform structure.

[0046] Figure 5 It is a schematic diagram of the calibration antenna placed on the calibration pole.

[0047] Figure 6 This is a schematic diagram of star calibration.

[0048] Figure 7 is the navigation coordinate system O n X n Y n Z n and a schematic diagram of the geographic coordinate system ENU.

[0049] Figure 8 is the vehicle coordinate system O b X b Y b Z b Schematic diagram of .

[0050] Fig. 9 It is a diagram of the top-down angle of inertial navigation calibration. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] It should be noted that in the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "up", "down", "top", "bottom", "one side", "the other side", "left", "right", etc. is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, and does not mean that the device or element must have a specific orientation, be constructed and operated in a specific orientation.

[0053] The inertial navigation calibration process of the mobile platform is as follows: Figure 1 As shown, before the inertial navigation system 7 is calibrated, the photoelectric axis consistency calibration is first completed, such as Figure 2 As shown, P is the distance between the antenna center and the low-light television 10, which is also equal to the distance between the calibration antenna 13 and the optical target 10.

[0054] The specific process of the calibration method is as follows: ① place the calibration antenna 13 and the optical target 10 in the far field; ② the relative position of the optical target 10 and the calibration antenna 13 is mirror-symmetrical to the relative position of the center of the low-light television 8 and the measurement and control antenna 6; ③ the calibration antenna 13 transmits a calibration signal to align the center of the electric axis of the measurement and control antenna 6 with the calibration antenna 13; ④ adjust the low-light television 8 so that the optical axis is aligned with the optical target 10, and at this time the two straight lines of the electric axis and the optical axis are parallel. The photoelectric axis consistency error is approximately: , in arc seconds, where Indicates the reading error of the optical target 10, which is generally the minimum scale length of the cursor. Indicates the distance between the low-light TV 8 and the optical target 10. Choose a suitable distance , so that the photoelectric axis consistency error < , is the inertial navigation accuracy, in arc seconds. At the same time, the calibration antenna 13 also meets the far-field condition, that is, the distance between the calibration antenna 13 and the measurement and control antenna 6 is ,in, is the diameter of the measurement and control antenna, The placement positions of the low-light television 10 and the calibration antenna 13 should satisfy both and distance requirement.

[0055] For a certain measurement and control system, the navigation accuracy requirement is <20″, =0.01m, then ≥103.2m; Simultaneously calculate the far field area of ​​the measurement and control antenna 6 ≥2000m, so the placement location of the low-light television 10 and the calibration antenna 13 should be ≥2000m.

[0056] The structure and appearance diagram of the mobile measurement and control platform are as follows: Figure 3 and Figure 4 As shown, refer to Figure 3 , place the vehicle on a hard surface, turn off the engine and keep it stationary, and roughly level the large plate. By adjusting the leveling mechanism 4, the vehicle chassis is level, that is, the vehicle coordinate system is horizontal. Horizontal plane with navigation coordinate system Parallel, the horizontal accuracy of the disk after adjustment is better than the preset accuracy ; Generally, it is the leveling accuracy of the large plate. In a certain measurement and control system, the leveling accuracy of the large plate is about 0.05° (i.e. 180″). Figure 4 ;

[0057] Reference Figures 5 to 8 , through geodetic measurement and calculation based on the vehicle structure parameters, the coordinates of the center of the 6 phases of the measurement and control antenna in the ENU coordinate system are obtained Generally speaking, the ENU coordinate system is different from the navigation coordinate system. coincide;

[0058] Reference Figure 6 , the star 14 that needs to be aligned, use the image level to fine-tune the level of the disk, so that the level accuracy of the disk meets the preset accuracy The specific method is: place the image level on the 6-azimuth turntable platform of the measurement and control antenna, with the knob end of the image level facing the azimuth rotation center, fix the antenna elevation angle; start from 0°, rotate the antenna azimuth, and read the image level reading every 15° and azimuth encoder readings Once, until 345°; sort out the data and find out the maximum tilt direction of the disk and maximum tilt By adjusting the leveling mechanism 4, the unevenness of the large plate can be corrected, and then this step is repeated until the maximum unevenness of the large plate meets the preset accuracy. ; Should be less than the heading accuracy of INS 7 , in a certain measurement and control system, the heading accuracy <20″, measurement accuracy of the combined level <10″, can meet the requirements;

[0059] The inertial navigation system is turned on for rough alignment and fine alignment to obtain the attitude matrix of the inertial navigation coordinate system and the navigation coordinate system, that is, the inertial navigation heading angle , pitch angle and roll angle , at this time the pitch angle and roll angle data are approximately 0°, that is, ;

[0060] like Fig. 9As shown, the optical target 10 is placed in the far field of the antenna, and can be placed on the front calibration pole, calibration tower or other high ground that meets the calibration conditions, such as the top of a mountain, the top of a building, etc.; the low-light television 8 is used to aim at the optical target 10 and measure the coordinates of the center of the optical target 10 in the ENU coordinate system ; Read the value of the antenna horizontal encoder , that is, the angle between the pointing direction of the measurement and control antenna 6 and the azimuth of the vehicle coordinate system 0°;

[0061] Correct the attitude matrix output by the inertial navigation system 7 so that the coordinate system of the inertial navigation system 7 coincides with the coordinate system of the vehicle. Specifically, correct the pitch angle and roll angle output by the inertial navigation system 7 to 0°, that is, , the heading angle output by the corrected inertial navigation 7 is ,in is the vector of the line connecting the vehicle and the optical target 10 in the horizontal plane of the navigation coordinate system The angle between the projection and the navigation coordinate system azimuth 0° (i.e. due north), , ;

[0062] The three-dimensional coordinates of the phase center of the measurement and control antenna 6 and the center of the inertial navigation 7 are measured, and the position information of the inertial navigation 7 is corrected so that the output position center of the inertial navigation 7 coincides with the phase center of the measurement and control antenna 6.

[0063] The vehicle chassis is firmly connected to the measurement and control antenna 6, and the azimuth rotation platform of the measurement and control antenna 6 is parallel to the vehicle chassis; the inertial navigation 7 mounting platform is firmly connected to the measurement and control antenna 6, and when the measurement and control antenna 6 is erected, the inertial navigation 7 mounting platform is parallel to the azimuth rotation platform of the measurement and control antenna 6; the inertial navigation 7 is installed on the inertial navigation mounting platform and is firmly connected to ensure that the position does not move during the maneuvering of the vehicle and the ups and downs of the antenna.

[0064] The position measurement of the vehicle-mounted measurement and control antenna 6 and the optical target 10 can be carried out by using differential GPS, total station and other methods. The azimuth error caused by the positioning error should be lower than the inertial navigation heading accuracy, that is, the position error ,in, The optical target 10 and the measurement and control antenna 6 are in the horizontal plane of the navigation coordinate system. The projection distance, It is the navigation accuracy of inertial navigation 7, in arc seconds.

[0065] Through the above method, high-precision calibration of the inertial navigation system 7 under the vehicle-mounted mobile platform can be achieved.

[0066] The mobile platform relied on by this embodiment includes a carrier vehicle, a cabin 5, a measurement and control antenna 6, a measurement and control equipment 9, an inertial navigation system 7, a low-light-level television 8, an optical target 10 and other parts; the carrier vehicle includes a tractor 1 and a semi-trailer 2, and a leveling mechanism 4 is installed around the chassis of the semi-trailer 2; the cabin 5 is installed on the semi-trailer 2, and includes an equipment cabin 11 and an antenna cabin 12; the measurement and control antenna 6 is installed in the antenna cabin 12, and is fixedly connected to the chassis of the semi-trailer 2; the inertial navigation system 7 is installed on the inertial navigation installation platform on the side of the sleeve of the measurement and control antenna 6; the low-light-level television 8 is installed behind the measurement and control antenna 6, and the lens faces the direction of the antenna wave; the measurement and control equipment 9 is installed in the equipment cabin 11; the optical target 10 is located in the far field area outside the carrier vehicle.

Claims

1. A mobile platform inertial navigation calibration method, characterized in that: The specific methods include the following: Step 1, install the low-light television (8) and make its lens face the direction of the antenna wave to complete the photoelectric axis consistency calibration; Step 2: Place the vehicle on a hard surface, turn off the engine and keep it stationary. First, roughly level the chassis. Then, adjust the leveling mechanism (4) of the vehicle to make the chassis of the vehicle horizontal, that is, the horizontal plane X of the vehicle coordinate system. b O b Y b Horizontal plane X with navigation coordinate system n O n Y n Parallel, the horizontal accuracy of the disk after adjustment is better than the preset accuracy Step 3: Obtain the coordinates of the center of the measurement and control antenna (6) on the vehicle in the ENU coordinate system through geodetic measurement and calculation of the vehicle structure parameters [x n1 ,y n1 , z n1 ]; Step 4: Use the image level to fine-tune the level of the plate to make the plate level meet the preset accuracy. Step 5, the inertial navigation (7) is turned on for coarse alignment and fine alignment, and the attitude matrix of the inertial navigation coordinate system and the navigation coordinate system is obtained, that is, the inertial navigation heading angle φ, pitch angle θ and roll angle γ, and the pitch angle and roll angle data are approximated to 0°, that is, θ≈0°, γ≈0°; Step 6: Place the optical target (10) in the far field of the antenna, align the measurement and control antenna with the direction of the optical target (10) through the low-light television (8), and measure the coordinates [x n2 ,y n2 , z n2 ]; read out the value φ1 of the antenna horizontal encoder, i.e., the angle between the pointing direction of the measurement and control antenna (6) and the direction 0° of the vehicle coordinate system; Step 7, correcting the attitude matrix output by the inertial navigation (7) so that the inertial navigation coordinate system coincides with the vehicle coordinate system; Step 8, measuring the three-dimensional coordinates of the phase center of the measurement and control antenna (6) and the center of the inertial navigation (7), and correcting the position information of the inertial navigation (7) so that the output position center of the inertial navigation (7) coincides with the phase center of the measurement and control antenna (6); The specific process of photoelectric axis consistency calibration in step 1 is as follows: Step 101, placing a calibration antenna (13) and an optical target (10) in a far field area; Step 102, the relative position of the optical target (10) and the calibration antenna (13) is mirror-symmetrical to the relative position of the low-light television (8) and the measurement and control antenna center; Step 103, the calibration antenna (13) transmits a calibration signal to align the electric axis center of the measurement and control antenna (6) with the calibration antenna (13); Step 104, adjusting the low-light television (8) so that the optical axis is aligned with the optical target (10), and at this time, the electric axis and the optical axis are parallel to each other; The error of the above photoelectric axis consistency is: The unit is arc seconds, wherein k represents the reading error of the optical target (10), is the smallest scale unit of the scale plate, and R represents the distance between the low-light television (8) and the optical target (10); Choose a suitable distance R to make the photoelectric axis consistency error φ e is the navigation accuracy of the inertial navigation system (7), in arc seconds; the calibration antenna (13) should satisfy the far-field condition, that is, the distance between the calibration antenna (13) and the measurement and control antenna (6) is R′>2D 2 / λ, where D is the diameter of the measurement and control antenna (6) and λ is the carrier wavelength of the calibration signal.

2. A mobile platform inertial navigation calibration method according to claim 1, characterized in that: The mobile platform used comprises a carrier, a cabin (5), a measurement and control antenna (6), a measurement and control device (9), an inertial navigation system (7), a low-light television (8) and an optical target (10); the carrier comprises a tractor (1) and a semitrailer (2), the semitrailer (2) is towed by the tractor (1), and a leveling mechanism (4) is installed around the chassis of the semitrailer; the cabin (5) is installed on the semitrailer (2), and comprises an equipment cabin (11) and an antenna cabin (12); wherein the measurement and control antenna (6) is installed on the antenna cabin (12) and is fixedly connected to the chassis of the semitrailer (2); the inertial navigation system (7) is installed on an inertial navigation installation platform on the side of the sleeve of the measurement and control antenna (6); the low-light television (8) is installed behind the measurement and control antenna (6), with the lens facing the direction of the antenna wave; the measurement and control device (9) is installed in the equipment cabin (11); and the optical target (10) is located in the far field area outside the carrier.

3. The mobile platform inertial navigation calibration method according to claim 1, characterized in that: The ENU coordinate system in step 3 is different from the navigation coordinate system X n Y n Z n coincide.

4. The method for calibrating an inertial navigation system of a mobile platform according to claim 1, characterized in that: The specific process of step 4 is as follows: Step 401, placing an image level on the azimuth turntable platform of the measurement and control antenna (6), with the knob end of the image level facing the azimuth rotation center, to fix the antenna elevation angle; Step 402, starting from 0°, rotate the antenna azimuth and read the image level reading M every 15° i and azimuth encoder reading A i Once, until 345°; sort out the data and find out the maximum tilt direction A of the disk m and the maximum tilt δ i ; Step 403, calibrate the levelness of the plate by adjusting the leveling mechanism (4), and then repeat step 402 until the maximum levelness of the plate meets the preset accuracy.

5. The method for calibrating an inertial navigation system of a mobile platform according to claim 1, characterized in that: The specific process of step 7 is as follows: First, the pitch angle and roll angle output by the corrected inertial navigation (7) are 0°, that is, θ=0°, γ=0°. Second, the heading angle output by the corrected inertial navigation (7) is φ2-φ1; wherein φ2 is the vector of the line connecting the phase center of the measurement and control antenna (6) and the optical target (10) in the horizontal plane X of the navigation coordinate system. n O n Y n The angle between the projection and the navigation coordinate system azimuth 0°, Where η = 180 × atan (y n2 -y n1 , x n2 -x n1 ) / π, abs means absolute value, and atan means inverse tangent.

6. The mobile platform inertial navigation calibration method according to claim 1, characterized in that: The preset accuracy of the large plate horizontal coarse adjustment Equal to the leveling accuracy of the leveling mechanism (4), fine adjustment accuracy Less than the inertial navigation accuracy φ e The rough adjustment process of the plate level is automatic or manual leveling through the leveling mechanism (4).

7. The method for calibrating an inertial navigation system of a mobile platform according to claim 1, characterized in that: The position measurement of the vehicle-mounted measurement and control antenna (6) and the optical target (10) adopts high-precision measurement methods such as differential GPS or total station, so that the azimuth error caused by the positioning error is lower than the heading accuracy φ of the inertial navigation (7) e , that is, the position error Wherein, L is the distance between the optical target (10) and the measurement and control antenna (6) in the horizontal plane X of the navigation coordinate system. n O n Y n projection distance.

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