CN113483784B - Optical fiber inertial measurement unit digital coordinate system and structure coordinate system error calibration test equipment and method - Google Patents
Optical fiber inertial measurement unit digital coordinate system and structure coordinate system error calibration test equipment and method Download PDFInfo
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Abstract
The invention discloses an error calibration test method and equipment for an inertial measurement combination digital coordinate system and a structural coordinate system, wherein the equipment comprises the following steps: a base; two support frames arranged on the base; two transverse rotating shafts respectively arranged on the two supporting frames; the left end and the right end of the box body are respectively connected with the two transverse rotating shafts; the fixing seat is fixedly arranged on the inner wall of the box body; the fixed seat is provided with a longitudinal rotating shaft; the placing table top is fixedly connected with the longitudinal rotating shaft and used for installing an inertial measurement unit; the temperature control cabinet is connected with the incubator; the driving device is respectively connected with the two transverse rotating shafts and the longitudinal rotating shaft; the inertia measurement combination testing device is connected with the inertia measurement combination through a CAN bus; and the measurement and control cabinet is respectively connected with the driving device and the inertia measurement combined testing device. The method for calibrating the errors of the inertial measurement combined digital coordinate system and the structural coordinate system has the advantages of simple test, accurate result and high efficiency.
Description
Technical Field
The invention relates to an error calibration method for a digital coordinate system and a structural coordinate system of an optical fiber inertial measurement unit, and belongs to the technical field of inertial measurement unit testing.
Background
The optical fiber inertial measurement unit mainly comprises 3 optical fiber gyroscopes, 3 accelerometers, a transposition mechanism and related circuits, and is mainly used for sensing angular velocity and acceleration of a carrier in motion and obtaining attitude and position information of the carrier in motion through navigation calculation.
The optical fiber inertial measurement unit coordinate system is divided into two types, namely a digital coordinate system and a structural coordinate system. The digital coordinate system is a virtual reference inside the inertial measurement unit, and calibration parameters of the inertial measurement unit are established on the basis of the digital coordinate system (an accelerometer coordinate system). The structure coordinate system is a structure installation reference outside the inertial measurement unit, and has an accurate side leaning surface and a horizontal installation surface, so that the unification with the system coordinate system is realized. In system application, inertial measurement unit calibration parameters are adopted for navigation calculation, and a control instruction is sent according to the calculated attitude and position result to control a steering engine to rotate and move according to a preset track. Because the parameters of the inertial measurement unit are established on the basis of a digital coordinate system, and rotating parts such as a steering engine and the like correspond to a structural coordinate system of the inertial measurement unit, the digital coordinate system and the structural coordinate system are theoretically completely consistent in order to ensure the precision of closed-loop control.
The fiber optic inertial measurement unit digital coordinate system is established on the sensitive axes of the internal three orthogonal accelerometers, and once the accelerometers are installed in place on the internal body, the digital coordinate system is relatively determined. Then, the body is installed on an external flange through switching of an indexing mechanism, a locking mechanism and the like, and finally the whole machine is installed on a system bracket together. The mounting flange is used as a structural carrier and an external structural interface of the optical fiber inertial measurement unit, is provided with a horizontal mounting base surface and a vertical mounting base surface, and is mounted by being attached to a reference surface of a system structural support to realize the unification and the fixation with a system coordinate system, namely the inertial measurement unit structural coordinate system is established on the external mounting flange. Because the axial deviation of different accelerometers is different, the digital coordinate system of each set of products is different, the structural coordinate system established on the mounting flange is ensured by structural precision machining, and the difference between different products can be basically ignored.
Because the digital coordinate systems of each set of products are different and the two structural coordinate systems are basically the same, certain deviation exists between the two coordinate systems, and test compensation is needed to reduce the influence on navigation and closed-loop control precision. The mechanism of the coordinate system deviation is analyzed, and is mainly influenced by the axial difference of the accelerometers and the errors of the structure processing precision, the assembly precision of the indexing mechanism and the like, so a set of precise testing equipment and a method are needed to ensure the precision of the calibrated deviation value. At present, the calibration method between the domestic and the foreign coordinate systems mainly focuses on the calibration between the digital coordinate system of the inertial measurement unit and the information of the foreign coordinate system, namely, after the product is installed in the system, the calibration of the coordinate system error is carried out on the system, which involves a large workload and is complicated in calibration, and if the inertial measurement unit needs to be calibrated again on the system after being replaced, the whole maintenance is not facilitated. By inquiring patent documents and data, the invention patent 'a multi-coordinate system calibration method of a single-axis modulation laser gyro inertial navigation system' discloses a multi-coordinate system calibration method of a single-axis modulation laser gyro inertial navigation system. The method includes the steps that an IMU is provided with a fitting reference surface on a marble, long-time power-on test is conducted, and then Euler angle calculation is conducted through calibration software to obtain an initial posture of the IMU; and then, an external theodolite aims at an external prism of the IMU to obtain an initial azimuth angle, so that the calibration of errors of a horizontal base plane, an azimuth prism coordinate system and an inertial navigation coordinate system is realized, and the complicated calibration work after the IMU is replaced is avoided.
The method has the advantages that the azimuth reference is established on the prism, an external theodolite is needed for aiming, and if the prism is not installed on a product, the deviation of the course angle cannot be effectively calibrated. Meanwhile, the internal course axis of the product is obtained by algorithm alignment calculation, is greatly influenced by external environment and internal parameters, can obtain higher precision within a longer time, and has limited testing efficiency and precision. Therefore, the invention provides the method for calibrating the error of the optical fiber inertial measurement unit coordinate system based on the rotary table, an external aiming prism is not needed, and the deviation of the coordinate system can be quickly obtained through the rotation of a plurality of positions of the rotary table.
Disclosure of Invention
The invention aims to overcome the defects in the application of the prior art and provides the error calibration test equipment and the method for the optical fiber inertial measurement unit digital coordinate system and the structural coordinate system.
The technical scheme adopted for realizing the aim of the invention is as follows: and after the optical fiber inertial measurement unit is electrified and stabilized, the double-shaft rotating table is controlled by the tester to complete rotation and static stop of the corresponding position according to the flow, and finally the deviation between the digital coordinate system and the structural coordinate system of the inertial measurement unit is obtained through calculation.
The invention provides an error calibration test device for a digital coordinate system and a structural coordinate system of an optical fiber inertial measurement unit, which comprises a base,
the two supporting frames are respectively and symmetrically arranged on two sides of the base;
two transverse rotating shafts with horizontal axes are respectively arranged on the two supporting frames;
the left end and the right end of the box body are respectively connected with the two transverse rotating shafts, and the box body is driven to rotate by the rotation of the two transverse rotating shafts;
the longitudinal rotating shaft is arranged in the box body in a vertical mode;
the mounting table is horizontally arranged and fixedly connected with the longitudinal rotating shaft, a reference surface is arranged on the mounting table, and a positioning pin for fixing the optical fiber inertial measurement unit is arranged on the reference surface;
the driving device is respectively connected with the two transverse rotating shafts and the longitudinal rotating shaft;
the inertial measurement unit testing equipment is connected with the optical fiber inertial measurement unit through a CAN bus; and
and the measurement and control cabinet is respectively connected with the driving device and the inertial measurement unit testing equipment.
Further, the X axis of the optical fiber inertial measurement unit is in the same direction as the axis of the longitudinal rotating shaft;
and the Y axis of the optical fiber inertial measurement unit is in the same direction as the axis of the transverse rotating shaft.
Further, the rotation direction of the longitudinal rotating shaft is controlled according to a right-hand rule, wherein the right-hand rule is as follows: holding the X axis by a right hand, enabling the thumb to face the positive direction of the X axis, and enabling the bending directions of other four fingers to be the rotating directions of the optical fiber inertial measurement unit 1; similarly, the direction of rotation of the transverse axis is controlled in the manner prescribed by the right hand rule described above.
The invention also provides a test method for error calibration by using the error calibration test equipment in the technical scheme, which comprises the following steps:
(1) the optical fiber inertial measurement unit is arranged on the placing table board, the side direction of the optical fiber inertial measurement unit is tightly attached to the positioning pin on the reference surface, and the optical fiber inertial measurement unit is fixed through a screw and connected with the cable among the inertial measurement unit testing equipment, the optical fiber inertial measurement unit and the measurement and control cabinet;
(2) after the optical fiber inertial measurement unit is electrified for a stable time, the inertial measurement unit testing equipment sends a self-checking signal to the measurement and control cabinet, the measurement and control cabinet sends an instruction to the driving device, the transverse rotating shaft and the longitudinal rotating shaft of the rotary table are controlled to return to the initial positions, and the result is fed back to the inertial measurement unit testing equipment;
(3) after the self-inspection is qualified, the inertial measurement unit testing equipment sends a transposition control signal to the measurement and control cabinet, the measurement and control cabinet analyzes a control command, and sends a transverse rotating shaft and longitudinal rotating shaft angle rotating command to the driving device, and the test comprises n rotating positions;
(4) the driving device respectively drives the transverse rotating shaft to drive the box body to rotate and drives the longitudinal rotating shaft to drive the placing table-board to rotate until the box body and the placing table-board rotate to the specified positions and are static;
(5) the inertial measurement unit testing equipment starts to test the data of the optical fiber inertial measurement unit, the testing time of each position is T, and the box body and the placing table top are kept in a static state all the time during the testing period;
(6) after the static test is finished, the inertial measurement unit testing equipment sends a transposition control instruction of the next position to the measurement and control cabinet, and the steps (4) and (5) are repeated until the test of all position data is finished;
(7) and calculating the deviation of the three-axis orthogonal axes of the coordinate system, namely the deviation between the axes of the optical fiber inertial set digital coordinate system X, Y, Z and the axes of the structure coordinate system X, Y, Z according to the obtained test data of all the positions.
Further, after the inertial measurement unit testing equipment stops at each static position, testing data of the optical fiber inertial measurement unit is started, the testing time is 60s, 11 arrays are obtained after the test is finished, and the rotating angle of the longitudinal rotating shaft and the rotating angle of the transverse rotating shaft are set as shown in the following table 1;
TABLE 1
| Position number | Longitudinal directionAngle of rotation (degree) | Transverse rotation shaft angle (°) | Residence time(s) |
| 1 | 0 | 0 | 60 |
| 2 | 0 | 90 | 60 |
| 3 | 0 | 180 | 60 |
| 4 | 0 | 270 | 60 |
| 5 | 90 | 270 | 60 |
| 6 | 180 | 270 | 60 |
| 7 | 270 | 270 | 60 |
| 8 | 270 | 180 | 60 |
| 9 | 270 | 90 | 60 |
| 10 | 270 | 0 | 60 |
| 11 | 0 | 0 | 60 |
Assuming that the rotation speed of the longitudinal rotating shaft or the transverse rotating shaft is ω and the rotation time is t, the relationship between the two positions is ω × t equal to 90 °.
Further, the specific implementation manner of calculating the deviation of the three orthogonal axes of the coordinate system in the step (7) is as follows;
in the formula, Kxy, Kxz and Kyz are known installation errors of the Y-direction accelerometer relative to an X axis of a digital coordinate system, installation errors of the Z-direction accelerometer relative to the X axis of the digital coordinate system and installation errors of the Z-direction accelerometer relative to a Y axis of the digital coordinate system respectively, and are known quantities;
k0X, k0Y and k0Z are respectively zero offset of the accelerometer in the X direction, the Y direction and the Z direction under the structure coordinate system, k1X, k1Y and k1Z are respectively scale factors of the accelerometer in the X direction, the Y direction and the Z direction under the structure coordinate system, kyz is installation error of the accelerometer in the Z direction relative to the Y axis of the structure coordinate system, kxz is installation error of the accelerometer in the Z direction relative to the X axis of the structure coordinate system, kxy is installation error of the accelerometer in the Y direction relative to the X axis of the structure coordinate system, wherein the following numbers represent the installation error obtained by different calculation modes; NAxi is the total number of pulses output to the accelerometer from X in the ith T time node, NAyi is the total number of pulses output to the accelerometer from Y in the ith T time node, NAzi is the total number of pulses output to the accelerometer from Z in the ith T time node, wherein i is 1,2.
Alpha ZF is the deviation between the Z axis of the optical fiber inertia unit digital coordinate system and the Z axis of the structural coordinate system;
alpha YF is the deviation between the Y axis of the optical fiber inertia group digital coordinate system and the Y axis of the structure coordinate system;
alpha XF is the deviation between the X axis of the fiber optic inertial measurement unit digital coordinate system and the X axis of the structural coordinate system.
The invention has the characteristics of simple test, convenience, rapidness, accuracy, reliability and the like, and can carry out test work without additional equipment and preparation work by only providing a double-shaft turntable and installing a product on a table board; in the test, the turntable is controlled by software to rotate according to the flow, corresponding inertial measurement unit static data is obtained, and a corresponding coordinate system error angle is obtained through calculation; because the rotary table has a precise structure reference, the navigation settlement in the product is not needed in the test, the coupling among different errors is reduced, and the test result is accurate and reliable.
Drawings
FIG. 1 is a schematic structural diagram of an error calibration apparatus of a coordinate system according to the present invention;
FIG. 2 is a schematic view of an installation structure of the inertial measurement unit of FIG. 1;
FIG. 3 is a diagram of the relationship between the digital coordinate system and the structural coordinate system of the present invention;
FIG. 4 is a coordinate system installation diagram using the coordinate system error calibration test of FIG. 1;
FIG. 5 is a flow chart of the test for coordinate system error calibration;
Detailed Description
The technical solution of the present invention is further explained with reference to the drawings and the embodiments.
As shown in fig. 1 and fig. 2, an optical fiber inertial measurement unit digital coordinate system and structural coordinate system error calibration test apparatus provided in an embodiment of the present invention includes: a base 9; a left support frame 10.1 and a right support frame 10.2 are respectively arranged on the base 9; the left support frame 10.1 and the right support frame 10.2 are respectively provided with a left transverse rotating shaft 2.1 and a right transverse shaft 2.2, and the axes of the left transverse rotating shaft 2.1 and the right transverse shaft 2.2 are both in the horizontal direction. Be equipped with box 3 between left transverse rotating shaft 2.1 and the right transverse shaft 2.2, both ends are connected with left transverse rotating shaft 2.1 and right transverse shaft 2.2 respectively about box 3 promptly, can drive box 3 and rotate round the horizontal axis when left transverse rotating shaft 2.1 and right transverse shaft 2.2 rotate.
The optical fiber inertial measurement unit comprises an inner longitudinal rotating shaft 8 of a box body 3, the axis of the longitudinal rotating shaft 8 is in the vertical direction, a placing table surface 7 is arranged outside the longitudinal rotating shaft 8, an optical fiber inertial measurement unit 1 is installed on the placing table surface 7 and is close to a reference surface 4, the reference surface is used for ensuring that the installation of optical fiber inertial measurement unit products meets the requirements of levelness and verticality and is fixed on the installing table surface, a high-precision reference installing surface is also arranged on the side surface of the optical fiber inertial measurement unit 1, and the surface needs to be attached to and installed with a positioning pin of the reference surface 4 on the placing table surface 7. When the longitudinal rotating shaft 8 rotates, the placing table surface 7 is driven to rotate, so that the optical fiber inertial measurement unit 1 is driven to rotate.
The left transverse rotating shaft 2.1, the right transverse shaft 2.2 and the longitudinal rotating shaft are respectively connected with a driving device 5, and the driving device 5 is used for driving the two transverse rotating shafts 2.1 and 2.2 and the longitudinal rotating shaft 8 to rotate.
The device also comprises a measurement and control cabinet 6 and an inertial measurement unit testing device 11, wherein the measurement and control cabinet 6 is used for receiving an instruction signal of the inertial measurement unit testing device 11, converting the instruction signal and then sending the converted instruction signal to the driving device 5 to control the rotation of the transverse rotating shaft and the longitudinal rotating shaft. The inertial measurement unit testing device 11 is connected with the inertial measurement unit 1 and the measurement and control cabinet 6, and is mainly used for testing data of the optical fiber inertial measurement unit 1 and sending a transposition control instruction to the measurement and control cabinet 6.
The above-mentioned testing of the data of the optical fiber inertial measurement unit 1 by the inertial measurement unit testing device 11, controlling the testing and controlling cabinet 6, and driving the indexing device 5 to realize the rotation of the longitudinal rotating shaft and the transverse rotating shaft are common technical means used by those skilled in the art, and are not described herein again.
As shown in FIG. 3, the optical fiber inertial measurement unit digital coordinate system is OXMYMZMThe structure coordinate system is OXFYFZF. The two coordinate systems are orthogonal coordinate systems, the mutual conversion can be expressed by three Euler angles, and the conversion angle sign and the rotation sequence from the structural coordinate system to the inertial set digital coordinate system are defined as alphazFαyFαxF
As shown in fig. 4, the installation direction of the optical fiber inerter 1 is: the axis directions of the X axis and the longitudinal rotating shaft are the same; the Y axis of the inertia measurement assembly is the same as the axis direction of the transverse rotating shaft. In this embodiment, the rotation direction of the longitudinal shaft is controlled according to the right-hand rule, wherein the right-hand rule is as follows: holding the X axis by the right hand, enabling the thumb to face the positive direction of the X axis, and enabling the bending directions of other four fingers to be the rotating direction of the inertia measurement assembly 1; similarly, the present embodiment controls the rotation direction of the transverse rotation shaft in the prescribed manner of the right-hand rule described above. The above is only an exemplary description that the rotation direction of the inertia measurement assembly is controlled by the longitudinal rotating shaft and the transverse rotating shaft, and the actual application can be changed correspondingly according to specific situations.
As shown in fig. 5, the method for calibrating errors of the optical fiber inertial measurement unit digital coordinate system and the structure coordinate system comprises the following steps:
(1) the optical fiber inertial measurement unit is arranged on the placing table board, the side direction of the optical fiber inertial measurement unit is tightly attached to the positioning pin on the reference surface, and the optical fiber inertial measurement unit is fixed through a screw and connected with the cable among the inertial measurement unit testing equipment, the optical fiber inertial measurement unit and the measurement and control cabinet;
(2) after the optical fiber inertial measurement unit is electrified for a stable time, the inertial measurement unit testing equipment 11 sends a self-checking signal to the measurement and control cabinet 6, the measurement and control cabinet 6 sends an instruction to the driving device 5, the transverse rotating shaft and the longitudinal rotating shaft of the rotary table are controlled to return to the initial positions, and the result is fed back to the inertial measurement unit testing equipment 11;
(3) after the self-inspection is qualified, the inertial measurement unit testing equipment 11 sends a transposition control signal to the measurement and control cabinet 6, the measurement and control cabinet 6 analyzes the control command and sends angle rotation commands of the transverse rotating shaft and the longitudinal rotating shaft to the driving device 5, and the test comprises n rotating positions;
(4) the driving device 5 respectively drives the left transverse rotating shaft 2.1 and the right transverse shaft 2.2 to drive the box body 3 to rotate and drives the longitudinal rotating shaft to drive the placing table-board 7 to rotate until the box body 3 and the placing table-board 7 rotate to the designated positions and are static;
(5) the inertial measurement unit testing equipment 11 starts to test the data of the optical fiber inertial measurement unit 1, the testing time of each position is T, and the box body 3 and the placing table top 7 are kept in a static state all the time during the testing period;
(6) after the static test is finished, the inertial measurement unit testing equipment 11 sends a next position transposition control instruction to the measurement and control cabinet 6, and the steps (4) and (5) are repeated until the test of all position data is finished;
(7) and calculating the deviation of the three-axis orthogonal axes of the coordinate system, namely the deviation between the axes of the optical fiber inertial set digital coordinate system X, Y, Z and the axes of the structure coordinate system X, Y, Z according to the obtained test data of all the positions.
In the present embodiment, the left transverse rotating shaft 2.1, the right transverse shaft 2.2, and the rotation rate ω of the longitudinal rotating shaft 8 are set, the time t of rotation is satisfied as ω × t being 90 °, ω is 10 °/s, t is 9s, 11 positions are provided, the dwell time in each rest position is 60s, and the angle of rotation of the longitudinal rotating shaft 8 and the angle of rotation of the left transverse rotating shaft 2.1 and the right transverse shaft 2.2 in the test are set as shown in table 1 below.
TABLE 1
After the inertial measurement unit testing equipment 11 stops at each static position, the data of the optical fiber inertial measurement unit 1 starts to be tested, the testing time is 60s, 11 arrays are obtained after the test is finished, and the accumulated inertial measurement unit data in each T time is as follows: let NAxi be the total number of pulses output to the accelerometer by X in the ith T time, NAyi be the total number of pulses output to the accelerometer by Y in the ith T time, and NAzi be the total number of pulses output to the accelerometer by Z in the ith T time, where i is 1,2.
The inertial measurement parameters that need to be known before coordinate system error calculation are the mounting errors Kxy, Kxz, Kyz of the accelerometers. And calculating all position data to obtain zero offsets k0x, k0y and k0z of the accelerometers, scale factors k1x, k1y and k1z and installation errors kxy, kxz and kyz, wherein the specific definitions are shown in table 2, and calculating the coordinate system offset angles alpha ZF, alpha YF and alpha XF through the installation errors kxy, kxz and kyz.
TABLE 2
| Serial number | (symbol) | Definition of |
| 1 | k1x | Scale factor of X-direction accelerometer |
| 2 | k1y | Scale factor of Y- |
| 3 | k1z | Z-direction accelerometer scale factor |
| 4 | k0x | Zero offset for X-direction accelerometer |
| 5 | k0y | Zero offset for Y-direction accelerometer |
| 6 | k0z | Zero offset for Z-direction accelerometer |
| 7 | kyz | Installation error of Z-direction accelerometer relative to Y-axis of structural coordinate |
| 8 | kxz | Installation error of Z-direction accelerometer relative to X axis of structural coordinate |
| 9 | kxy | Installation error of Y-direction accelerometer relative to X axis of structural coordinate system |
The calculation formula in the test process is as follows:
in the formula, k0X, k0Y and k0Z are respectively zero offset of an X-direction accelerometer, a Y-direction accelerometer and a Z-direction accelerometer under a structure coordinate system, k1X, k1Y and k1Z are respectively scale factors of the X-direction accelerometer, the Y-direction accelerometer and the Z-direction accelerometer under the structure coordinate system, kyz is installation error of the Z-direction accelerometer relative to a Y axis of the structure coordinate system, kxz is installation error of the Z-direction accelerometer relative to the X axis of the structure coordinate system, kxy is installation error of the Y-direction accelerometer relative to the X axis of the structure coordinate system, and the following numbers represent the installation error obtained by different calculation methods; NAxi is the total number of pulses output to the accelerometer from X in the ith T time node, NAyi is the total number of pulses output to the accelerometer from Y in the ith T time node, NAzi is the total number of pulses output to the accelerometer from Z in the ith T time node, wherein i is 1,2.
Alpha ZF is the deviation between the Z axis of the optical fiber inertia unit digital coordinate system and the Z axis of the structural coordinate system;
alpha YF is the deviation between the Y axis of the optical fiber inertia group digital coordinate system and the Y axis of the structure coordinate system;
alpha XF is the deviation between the X axis of the fiber optic inertial measurement unit digital coordinate system and the X axis of the structural coordinate system.
The deviation angle of the three-axis orthogonal axis of the coordinate system is obtained through calculation, the internal installation of a product can be checked accordingly, the using effect of the system can be evaluated, if the deviation angle exceeds a required value, the problem of assembly is reflected, extra non-negligible errors are brought when the system is used, the using precision and the overall performance of the system are affected, and the system needs to be repaired.
The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.
Claims (3)
1. The utility model provides an optic fibre is used to group digital coordinate system and structure coordinate system error calibration test equipment which characterized in that: comprises a base, a plurality of fixing rods and a plurality of fixing rods,
the two supporting frames are respectively and symmetrically arranged on two sides of the base;
two transverse rotating shafts with horizontal axes are respectively arranged on the two supporting frames;
the left end and the right end of the box body are respectively connected with the two transverse rotating shafts, and the box body is driven to rotate by the rotation of the two transverse rotating shafts;
the longitudinal rotating shaft is arranged in the box body in a vertical mode;
the mounting table is horizontally arranged and fixedly connected with the longitudinal rotating shaft, a reference surface is arranged on the mounting table, and a positioning pin for fixing the optical fiber inertial measurement unit is arranged on the reference surface;
the driving device is respectively connected with the two transverse rotating shafts and the longitudinal rotating shaft;
the inertial measurement unit testing equipment is connected with the optical fiber inertial measurement unit through a CAN bus; and
the measurement and control cabinet is respectively connected with the driving device and the inertial measurement unit testing equipment;
the test method for error calibration by using the error calibration test equipment comprises the following steps:
(1) the optical fiber inertial measurement unit is arranged on the placing table board, the side direction of the optical fiber inertial measurement unit is tightly attached to the positioning pin on the reference surface, and the optical fiber inertial measurement unit is fixed through a screw and connected with the cable among the inertial measurement unit testing equipment, the optical fiber inertial measurement unit and the measurement and control cabinet;
(2) after the optical fiber inertial measurement unit is electrified for a stable time, the inertial measurement unit testing equipment sends a self-checking signal to the measurement and control cabinet, the measurement and control cabinet sends an instruction to the driving device, the transverse rotating shaft and the longitudinal rotating shaft of the rotary table are controlled to return to the initial positions, and the result is fed back to the inertial measurement unit testing equipment;
(3) after the self-inspection is qualified, the inertial measurement unit testing equipment sends a transposition control instruction to the measurement and control cabinet, the measurement and control cabinet analyzes the control instruction, and sends angle rotation instructions of the transverse rotating shaft and the longitudinal rotating shaft to the driving device, and the test comprises n rotating positions;
(4) the driving device respectively drives the transverse rotating shaft to drive the box body to rotate and drives the longitudinal rotating shaft to drive the placing table-board to rotate until the box body and the placing table-board rotate to the specified positions and are static;
(5) the inertial measurement unit testing equipment starts to test the data of the optical fiber inertial measurement unit, the testing time of each position is T, and the box body and the placing table top are kept in a static state all the time during the testing period;
after the inertial measurement unit testing equipment stops at each static position, starting to test data of the optical fiber inertial measurement unit, wherein the testing time is 60s, 11 arrays are obtained after the test is finished, and the rotating angles of the longitudinal rotating shaft and the transverse rotating shaft are set as follows;
the position number is 1, the angle of the longitudinal rotating shaft is 0 degrees, the angle of the transverse rotating shaft is 0 degrees, and the retention time is 60 s;
the position number is 2, the angle of the longitudinal rotating shaft is 0 degrees, the angle of the transverse rotating shaft is 90 degrees, and the retention time is 60 s;
the position number is 3, the angle of the longitudinal rotating shaft is 0 degree, the angle of the transverse rotating shaft is 180 degrees, and the retention time is 60 s;
the position number is 4, the angle of the longitudinal rotating shaft is 0 degrees, the angle of the transverse rotating shaft is 270 degrees, and the retention time is 60 s;
the position number is 5, the angle of the longitudinal rotating shaft is 90 degrees, the angle of the transverse rotating shaft is 270 degrees, and the retention time is 60 s;
the position number is 6, the angle of the longitudinal rotating shaft is 180 degrees, the angle of the transverse rotating shaft is 270 degrees, and the retention time is 60 s;
the position number is 7, the angle of the longitudinal rotating shaft is 270 degrees, the angle of the transverse rotating shaft is 270 degrees, and the retention time is 60 s;
the position number is 8, the angle of the longitudinal rotating shaft is 270 degrees, the angle of the transverse rotating shaft is 180 degrees, and the retention time is 60 s;
the position number is 9, the angle of the longitudinal rotating shaft is 270 degrees, the angle of the transverse rotating shaft is 90 degrees, and the retention time is 60 s;
the position number is 10, the angle of the longitudinal rotating shaft is 270 degrees, the angle of the transverse rotating shaft is 0 degree, and the retention time is 60 s;
the position number is 11, the angle of the longitudinal rotating shaft is 0 degrees, the angle of the transverse rotating shaft is 0 degrees, and the retention time is 60 s;
recording the rotation speed of a longitudinal rotating shaft or a transverse rotating shaft as omega, the rotation time as t, and meeting the relation of omega x t as 90 degrees between two positions;
(6) after the static test is finished, the inertial measurement unit testing equipment sends a transposition control instruction of the next position to the measurement and control cabinet, and the steps (4) and (5) are repeated until the test of all position data is finished;
(7) calculating the deviation of the three-axis orthogonal axis of the coordinate system, namely the deviation between the X, Y, Z axis of the optical fiber inertia group digital coordinate system and the X, Y, Z axis of the structural coordinate system according to the obtained test data of all the positions;
the specific implementation manner of calculating the deviation of the three-axis orthogonal axis of the coordinate system in the step (7) is as follows;
in the formula, Kxy, Kxz and Kyz are known installation errors of the Y-direction accelerometer relative to an X axis of a digital coordinate system, installation errors of the Z-direction accelerometer relative to the X axis of the digital coordinate system and installation errors of the Z-direction accelerometer relative to a Y axis of the digital coordinate system respectively, and are known quantities;
k0X, k0Y and k0Z are respectively zero offset of the accelerometer in the X direction, the Y direction and the Z direction under the structure coordinate system, k1X, k1Y and k1Z are respectively scale factors of the accelerometer in the X direction, the Y direction and the Z direction under the structure coordinate system, kyz is installation error of the accelerometer in the Z direction relative to the Y axis of the structure coordinate system, kxz is installation error of the accelerometer in the Z direction relative to the X axis of the structure coordinate system, kxy is installation error of the accelerometer in the Y direction relative to the X axis of the structure coordinate system, wherein the following numbers represent the installation error obtained by different calculation modes; NAxi is the total number of pulses output to the accelerometer from X in the ith T time node, NAyi is the total number of pulses output to the accelerometer from Y in the ith T time node, NAzi is the total number of pulses output to the accelerometer from Z in the ith T time node, wherein i is 1,2.
Alpha ZF is the deviation between the Z axis of the optical fiber inertia unit digital coordinate system and the Z axis of the structural coordinate system;
alpha YF is the deviation between the Y axis of the optical fiber inertia group digital coordinate system and the Y axis of the structure coordinate system;
alpha XF is the deviation between the X axis of the fiber optic inertial measurement unit digital coordinate system and the X axis of the structural coordinate system.
2. The apparatus of claim 1, wherein the apparatus comprises:
the X axis of the optical fiber inertial measurement unit is in the same direction as the axis of the longitudinal rotating shaft;
and the Y axis of the optical fiber inertial measurement unit is in the same direction as the axis of the transverse rotating shaft.
3. The apparatus of claim 1, wherein the apparatus comprises: controlling the rotation direction of the longitudinal rotating shaft according to a right-hand rule, wherein the right-hand rule is as follows: holding the X axis by a right hand, enabling the thumb to face the positive direction of the X axis, and enabling the bending directions of other four fingers to be the rotating directions of the optical fiber inertial measurement unit; similarly, the direction of rotation of the transverse axis is controlled in the manner prescribed by the right hand rule described above.
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