High-precision light and small strapdown inertial measurement device

Abstract

The present application relates to inertial measurement device, the purpose is to solve the technical problem that the existing inertial measurement device is big in error, big in volume and weight and difficult to realize self-calibration and periodic maintenance function at any time and anywhere, provide a kind of high-precision light and small inertial measurement device;Three high-precision fiber gyroscopes are fixedly installed along three-axis direction in the inertial unit base, a double-axis indexing mechanism is used, the fiber gyroscope is kept unmoved, only the table body with the accelerometer of three-axis direction is rotated, and the self-calibration function is realized by ten-position adding table calibration technology, the influence of the body error of fiber inertial unit on navigation precision is inhibited by single-axis rotation modulation, the self-calibration precision and efficiency are improved, the periodic maintenance of inertial measurement device is finally realized, the requirement of high-precision navigation in the process of carrier movement is satisfied, and the volume and weight of the inertial measurement device are greatly reduced by this mechanical structure, and light weight is realized.

Description

Technical Field

[0001] This invention relates to inertial measurement devices, and more specifically to a high-precision, lightweight strapdown inertial measurement device. Background Technology

[0002] An inertial measurement unit (IMU) is a device that uses the principle of inertia to measure the motion state of an object. Specifically, it uses accelerometers and gyroscopes to measure the acceleration and angular velocity of the object in real time, and then uses algorithms such as integration to process these data to calculate the object's position, velocity, attitude, and other motion state parameters.

[0003] However, as the demand for more refined and precise navigation systems continues to increase, existing inertial measurement units (IMUs) have large errors and their performance can no longer meet the new requirements. In addition, existing IMUs are also bulky and heavy. Furthermore, pure strapdown IMUs require frequent returns to the factory for calibration and regular maintenance after delivery to users, which causes inconvenience to users. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problems of existing inertial measurement devices having large errors, large size and weight, and difficulty in achieving self-calibration and regular maintenance functions anytime and anywhere, and to provide a high-precision, lightweight strapdown inertial measurement device.

[0005] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0006] A high-precision, lightweight, and compact strapdown inertial measurement unit, characterized by the following features:

[0007] It includes a cavity structure with a base on its surface, and an optical fiber inertial navigation system body, a shifting mechanism, a locking mechanism and a control mechanism disposed within the cavity structure;

[0008] The indexing mechanism includes an integrated frame connected to the cavity structure via an outer shaft, a platform connected to the integrated frame via an inner shaft, an outer shaft torque motor and an outer shaft angle sensor respectively disposed at both ends of the outer shaft, and an inner shaft torque motor and an inner shaft angle sensor respectively disposed at both ends of the inner shaft; the axes of the inner shaft and the outer shaft are perpendicular to each other and located in the same plane;

[0009] The fiber optic inertial navigation system includes three fiber optic gyroscopes and three accelerometers; the three fiber optic gyroscopes are fixedly mounted on the base along the three axes; the three accelerometers are respectively mounted on the platform along the three axes.

[0010] The locking mechanism is used to lock and fix the position of the indexing mechanism;

[0011] The control mechanism is electrically connected to the locking mechanism, the outer shaft torque motor, the inner shaft torque motor, the outer shaft angle sensor, the inner shaft angle sensor, three fiber optic gyroscopes, and three accelerometers.

[0012] Furthermore, one of the fiber optic gyroscopes is integrated with the outer axis and the outer axis angle sensor.

[0013] Furthermore, the inner axis angle sensor includes an inner axis circular grating and an inner axis grating reading head. The inner axis circular grating is fixedly connected to the inner axis, and the inner axis grating reading head is correspondingly disposed on an integrated frame on one side of the inner axis circular grating.

[0014] The outer shaft angle sensor includes an outer shaft circular grating and an outer shaft grating reading head. The outer shaft circular grating is fixedly connected to the outer shaft, and the outer shaft grating reading head is correspondingly disposed on a base on one side of the outer shaft circular grating.

[0015] Furthermore, the locking mechanism adopts a double-end toothed disc engagement locking, and the locking of the indexing mechanism is achieved by controlling the disengagement and engagement of the two toothed discs;

[0016] The locking mechanism includes a fixed gear plate, a locking seat, a movable gear plate, a push rod, and two locking motors. The two locking motors, the fixed gear plate, and the locking seat are all mounted on the base. The movable gear plate is fixedly mounted on one end of the inner shaft connected to the inner shaft circular grating. The push rod is fixedly mounted on the outer wall of the integrated frame connected to the inner shaft torque motor. The two locking motors control the fixed gear plate and the locking seat to move in opposite directions along the inner shaft direction through a worm gear structure, so that the fixed gear plate and the movable gear plate mesh and lock, and the push rod and the locking seat engage and lock.

[0017] Furthermore, the control mechanism includes a data acquisition module, an inertial navigation system (INS) calculation module, a spinlock control module, and a communication module;

[0018] The data acquisition module is used to acquire digital signal data from the accelerometer and fiber optic gyroscope and transmit them to the inertial navigation system calculation module.

[0019] The inertial navigation system (INS) calculation module processes the digital signal data acquired by the data acquisition module and sends control signals to the spinlock control module. The INS includes an accelerometer self-calibration section and a modulation navigation section. The accelerometer self-calibration section is used to solidify the parameter calibration before the carrier runs and to perform calibration and correction during the carrier runs. The modulation navigation section is used to make the error of the fiber optic INS body present a periodic pattern through rotation modulation during the carrier runs, thereby suppressing the impact of error on navigation accuracy.

[0020] The rotary lock control module controls and coordinates the operation of the indexing mechanism and the locking mechanism according to the control signal output by the inertial navigation system (INS) calculation module, and cooperates with the INS calculation module to perform rotation modulation and locking.

[0021] The communication module is used for communication between the inertial navigation system (INS) calculation module and the ground test equipment.

[0022] Furthermore, the inertial navigation system (INS) calculation module can perform IIR filtering on the raw pulses from the 0.5ms fiber optic gyroscope and the raw pulses from the accelerometer acquired in real time by the data acquisition module.

[0023] Furthermore, the inertial navigation system (INS) calculation module employs multi-level temperature compensation technology, using a temperature compensation scheme based on constant-temperature fiber optic gyroscopes and accelerometers to achieve full parameter compensation.

[0024] Furthermore, the modulation navigation section uses acceleration measurement and angular velocity measurement to perform tool error compensation, and obtains real-time visual velocity increment, visual angle increment and instantaneous angular velocity in the three-axis directions.

[0025] Furthermore, the accelerometer self-calibration section adopts a ten-position accelerometer calibration technique. After IIR filtering, the acceleration components collected during the ten rotations are projected onto each coordinate axis. By establishing a mathematical model that includes accelerometer error parameters, the data collected from multiple positions are processed to solve for various error parameters of the accelerometer, thereby achieving 12-dimensional parameter calibration of the accelerometer.

[0026] Let the angles between the projection components of the X-axis onto the actual position coordinate axes and X1, Z1, and Y1 be A, B, and C, respectively. The calibration algorithm used in the ten-position addition calibration technique is as follows:

[0027]

[0028] In the formula, g is the gravitational acceleration at the calibration position, and a tx* The component of the accelerometer on the platform in the X-axis direction, a ty* The component of the accelerometer on the platform in the Y-axis direction, a tz* The component of the accelerometer on the platform in the Z-axis direction, A m For the scale factor corresponding to the X, Y, or Z axis measurement channel; A mj The installation error of the acceleration input shaft around the body shaft; a m0 This corresponds to the zero offset value of the X, Y, or Z axis axial measurement channel.

[0029] Furthermore, the modulation navigation section reads the pre-calibrated quadratic error parameters stored in the device when powered on, and compensates the digital signal data acquired by the data acquisition module according to the quadratic model and the quadratic error parameters, so as to reduce the impact of the quadratic error on the navigation accuracy.

[0030] Furthermore, after performing dual-position Kalman filtering alignment, the modulation navigation section performs single-axis rotation modulation. The modulation navigation sequence is 0°→180°→360°→180°→0°, and the rotation stop time, rotation time and stop can be set to achieve high-precision rotation modulation navigation.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) In this invention, the inertial measurement device mounts the accelerometer on the platform along the three-axis direction, and achieves a fixed connection with the integrated frame through the inner axis, and achieves two-level linkage between the inner and outer axes with the base on which the outer axis is installed. This not only improves the space utilization of the platform, but also enables the accelerometer rotation calibration compensation in conjunction with the inertial measurement module, so that this invention has self-calibration and rotation modulation functions, and improves navigation accuracy.

[0033] (2) In this invention, the inertial measurement device fixes three fiber optic gyroscopes on the base along the three-axis direction to achieve physical heterogeneity of the inertial instrument. It can keep the gyroscopes stationary during inertial measurement and only rotate the inner and outer axes to achieve modulation navigation, which reduces the sources of error and simplifies the system structure. In addition, one of the fiber optic gyroscopes is integrated with the outer axis and the outer axis angle sensor to further improve space utilization and meet the requirements of light and small size.

[0034] (3) The locking mechanism in the inertial measurement device of the present invention includes a fixed gear plate, a locking seat, a moving gear plate, a push rod and two locking motors. Specifically, the corresponding locking motors control the moving gear plate to mesh with the fixed gear plate through a worm gear structure. The push rod is engaged with the locking seat on the base to lock the position of the integrated frame. The rotary lock control module can drive the locking motor to work, which not only avoids the fiber optic inertial group from shifting position or changing attitude when it is not working, but also ensures measurement accuracy and reduces navigation errors caused by position changes.

[0035] (4) In this invention, the inertial measurement device adopts the ten-position addition table calibration technology. The self-calibration installation error of the addition table changes very little compared with the whole machine installation error under the locking condition. It can replace the whole machine calibration level and realize the self-calibration function. There is no need to perform return calibration, which improves the calibration efficiency. Moreover, rotation modulation provides favorable conditions for self-calibration, suppresses the influence of fiber optic inertial group error on navigation accuracy, and improves self-calibration accuracy.

[0036] (5) In this invention, the inertial measurement device performs high-precision navigation by real-time compensation of the accelerometer quadratic term, and can work stably under multi-physics field conditions. In addition, the use of multi-level temperature compensation technology in the early stage enables the system to achieve inertial navigation in a wide temperature range, so that this invention can meet the needs of future carrier systems to maintain high-precision inertial measurement for a long time. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the overall structure of a high-precision, lightweight, and compact strapdown inertial measurement device according to the present invention.

[0038] Figure 2 This is a partial structural diagram of the inner axis system of the integrated frame in an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the integrated structure of the fiber optic gyroscope, outer shaft, and outer shaft angle sensor in an embodiment of the present invention.

[0040] Figure 4 This is a schematic diagram of the data acquisition module in an embodiment of the present invention;

[0041] Figure 5 This is a diagram showing the self-calibration position sequence of the accelerometer in an embodiment of the present invention;

[0042] Figure 6 This is a diagram showing the navigation azimuth error curve after compensating for the quadratic acceleration term error in an embodiment of the present invention.

[0043] Figure 7 This is a schematic diagram of single-axis rotation modulation navigation sequence transfer in an embodiment of the present invention;

[0044] Figure 8 This is a schematic diagram of the pivot lock control module in an embodiment of a high-precision, lightweight strapdown inertial measurement system of the present invention.

[0045] Figure 9 This is a diagram showing the nineteenth position calibration sequence in an embodiment of a high-precision, lightweight strapdown inertial measurement system of the present invention.

[0046] In the diagram: 1-Base, 2-Integrated frame, 3-Platform, 4-Inner shaft, 5-Outer shaft, 6-Fiber optic gyroscope, 7-Accelerometer, 8-Inner shaft torque motor, 9-Inner shaft circular grating, 10-Inner shaft grating reading head, 11-Moving gear disk, 12-Push rod, 13-Outer shaft circular grating, 14-Outer shaft grating reading head. Detailed Implementation

[0047] The present invention will be further described in detail below with reference to specific embodiments. Note that the description is for explanation and not limitation of the present invention.

[0048] See appendix Figure 1 As shown, this embodiment provides a high-precision, lightweight strapdown inertial measurement unit (SMU), including a cavity structure with a base 1 on its surface, and three high-precision 140° fiber optic gyroscopes 6 fixedly mounted on the three-axis surfaces of the base 1; an integrated frame 2 is disposed inside the cavity structure, and a main body 3 is connected to the integrated frame 2 through an inner shaft 4, as shown in the attached figure. Figure 2As shown, the platform 3 has three positioning surfaces along the three axes, each equipped with an accelerometer 7. One end of the inner shaft 4 is fixedly connected to the output of the inner shaft torque motor 8, and the other end is fixedly connected to the inner shaft circular grating 9. The shaft end of the inner shaft 4 is also fixedly connected to a moving gear disk 11. The side of the integrated frame 2 away from the moving gear disk 11 is fixedly connected to a push rod 12. The corresponding locking motor, in conjunction with the worm gear structure, controls the fixed gear disk and locking seat on the base 1 to move in opposite directions along the inner shaft 4, causing the moving gear disk 11 to mesh with the fixed gear disk, and the push rod 6 to engage with the locking seat, thereby locking the position of the integrated frame. Figure 3 As shown, one end wall of the integrated frame 2 is fixedly connected to the output end of the external shaft torque motor via the external shaft 5. The external shaft torque motor is mounted on the base 1. The other end wall is fixedly connected to the external shaft circular grating 13 via the external shaft 5 and is rotatably connected to the base 1. The integrated frame 2 is also provided with two internal shaft grating reading heads 10 and external shaft grating reading heads 14, which correspond to the internal shaft circular grating 9 and the external shaft circular grating 13, respectively. These reading heads can convert the measured angular displacement into an electrical signal and transmit it to the control mechanism.

[0049] In order to reduce the size and weight of the inertial measurement device, the platform 3, which is equipped with the accelerometer 7, is integrated with the inner shaft 4, which greatly reduces the radius of rotation and reduces the weight and volume of the platform 3.

[0050] The worm gear structure includes a turbine and a worm shaft. The locking motor controls and drives the worm shaft to move linearly, thereby controlling the rotation direction of the turbine. The turbine is threadedly connected to the fixed gear plate or locking seat through a threaded rod. The fixed gear plate is equipped with positioning sliding guides on both sides, so that the rotation of the turbine drives the threaded rod to rotate. The fixed gear plate and locking seat connected to the threaded rod move towards each other along the direction of the inner shaft 4 under the orientation of the positioning sliding guides. Therefore, the locking and separation of the indexing mechanism and the base can be achieved simply by changing the rotation direction of the turbine through the locking motor.

[0051] A control mechanism is installed on the base 13. The control mechanism coordinates the rotation of the integrated frame 2 along the outer axis 5 and the rotation of the platform 3 along the inner axis 4, and controls the moving gear plate 11 to lock and fix the fixed gear plate, the push rod 12 and the locking seat.

[0052] The control mechanism in this embodiment specifically includes a data acquisition module, an inertial navigation system (INS) calculation module, a spinlock control module, and a communication module. The spinlock control module coordinates the operation of the rotation mechanism and the locking mechanism according to the control signals output by the INS calculation module. The communication module is used for communication with the ground test equipment.

[0053] The data acquisition module is attached. Figure 4As shown (the table in the figure represents the accelerometer), the data acquisition module includes an analog-to-digital converter circuit and a gyroscope demodulation circuit. It employs a 10-position static data acquisition method to collect digital signal data from the accelerometer and fiber optic gyroscope and transmit it to the inertial navigation system (INS) module. The INS module then calibrates the accelerometer using a 10-position table calibration technique, as shown in the attached diagram. Figure 5 As shown, the details are as follows:

[0054] The acceleration components collected during ten rotations are projected onto each coordinate axis to establish a mathematical model that includes accelerometer error parameters. Data collected from multiple positions are processed to obtain various error parameters of the accelerometer. Let the angles between the projected X-axis component on the actual position coordinate axis of the inertial navigation system and X1, Z1, and Y1 be A, B, and C, respectively. The ten-position calibration algorithm is as follows:

[0055]

[0056] In the formula, g is the gravitational acceleration at the calibration position, and a tx* The component of the accelerometer on the platform in the X-axis direction, a ty* The component of the accelerometer on the platform in the Y-axis direction, a tz* The component of the accelerometer on the platform in the Z-axis direction, A m For the scale factor corresponding to the X, Y, or Z axis measurement channel; A mj The installation error of the acceleration input shaft around the body shaft; a m0 The zero offset value is corresponding to the axial measurement channel of the X, Y or Z axis; the same method is used to project the Z1 and Y1 axes, so it will not be described again.

[0057] The inertial navigation system (INS) module can acquire the raw pulses from the fiber optic gyroscope and accelerometer in real time (0.5ms), perform IIR filtering, then perform multi-level temperature compensation, and then use acceleration and angular velocity measurements to perform tool error compensation, thereby obtaining the real-time angular velocity increment, viewing angle increment, and instantaneous angular velocity in the three-axis directions.

[0058] The tool error compensation for acceleration measurement is shown in Equation ①:

[0059]

[0060] In the formula: T s Sampling period, in seconds; N ax N ay N az These are the apparent acceleration increments output from the X, Y, and Z axis axial acceleration measurement channels, in units of ^ / T. s ;K 0x K 0y K 0zThese are the zero offset values ​​for the X, Y, and Z axis axial measurement channels, in units of ^ / s; K 1x K 1y K 1z These are the scale factors for the X, Y, and Z axis measurement channels, respectively, in units of ^ / (g·s); K yx K zx K xy K zy K xz K yz J Y Acceleration input axes around the body axes Y, Z, J X Acceleration input axis around body axis X, Z, J Z Installation error of the acceleration input shaft around the body axis X and Y, in units of ^ / (g·s).

[0061] The tool error compensation for angular velocity measurement is shown in Equation ②:

[0062]

[0063] Where: N ωx N ωy N ωz These represent the increments of the gyroscope's rotational angular velocity output in the X, Y, and Z directions, respectively, in units of ^ / T. s E 0x E 0y E 0z The constant drift values ​​of the gyroscopes in the X, Y, and Z directions are respectively, in units of ^ / s; E 1x E 1y E 1z They are respectively gyroscope G X G Y and G Z The scaling factor, in units of ^ / "; E xy E yx E xz E zx E zy E yz G X Input axis around body axes Y, Z, G Y Input axis around body axis X, Z, G Z The installation error of the input shaft around the body axis X and Y, in units of ^ / ", is converted into angular velocity by dividing the angle increment after tool error by the sampling time, thus enabling real-time measurement of angular velocity.

[0064] The input-output characteristics of accelerometers are usually described by algebraic equations, the most common being a quadratic equation in one variable, i.e., a model with added quadratic terms:

[0065]

[0066] Where E is the accelerometer output, in units of (V); a i K0 is the accelerometer input, in g; K1 is the bias value, in V; K2 is the scale factor, in V / g; K2 is the second-order nonlinear coefficient, in V / g. 2 ).

[0067] Through calibration compensation of the quadratic term of the acceleration, the error of the quadratic term of the eastward accelerometer is K2Y = -0.3 * 10. -6 g / g 2 The quadratic term of the northbound accelerometer is K2Z = 0.2 * 10. -6 g / g 2 ; as attached Figure 6 As shown, the quadratic term of the astronomical accelerometer is K2X = 0.2 * 10. -6 g / g 2 Then, single-axis rotation modulation technology is used to control the rotation and locking of the inner and outer axes, and to perform real-time high-precision position calculation, as shown in the attached figure. Figure 7 As shown, the modulation navigation sequence is 0°→180°→360° (clockwise)→180°→0° (counterclockwise). Navigation analysis shows that the altitude direction is greatly improved, and the dimensional direction can also be improved.

[0068] The inertial navigation system (INS) calculation module also establishes the relationship between the angular rate and acceleration measurement information output by the INS and temperature variations. The goal is to achieve full-temperature consistency of the angular rate and acceleration measurement information output by the INS. Temperature compensation is achieved by designing a temperature modeling test environment and test methods for fiber optic INS, as detailed below:

[0069] S1: Temperature hysteresis test. Perform low temperature → high temperature → low temperature tests according to product specifications to analyze whether the temperature hysteresis of the inertial measurement channel meets the requirements.

[0070] S2: Temperature compensation and verification are performed by the analog-to-digital conversion circuit in the data acquisition module;

[0071] S3: The tool error parameters are calibrated by using system-level calibration tests at multiple temperature points. The temperature compensation model is calculated by calculating the relationship between temperature and inertial navigation system output based on the test data at each temperature point.

[0072] S4: By obtaining the relationship between temperature change rate and accelerometer output through static testing processes at high temperature, low temperature and normal temperature, a temperature change-acceleration zero-position compensation model is obtained.

[0073] S5: Calculate temperature compensation parameters;

[0074] S6: Using the obtained parameters, substitute them into the preset model to perform error compensation on the inertial navigation system, and verify the compensation results.

[0075] Rotary lock control module as attached Figure 8 As shown, the CPU module, which includes a DSP, an FPGA, and corresponding peripheral circuits, serves as the hardware platform for the drive and control of the rotation and locking mechanisms. It is electrically connected to the inertial navigation system (INS) module, receives the modulation signals from the INS module, and controls the rotation angle and speed of the inner and outer frame bearings according to the pre-set modulation navigation sequence. This modulates the error parameters into periodic signals for compensation and correction, thereby improving navigation accuracy.

[0076] The specific working principle of this embodiment is as follows:

[0077] Before the vehicle equipped with the inertial measurement unit departs, the 24-dimensional error parameters of the inertial measurement unit are calibrated at nineteen positions, as shown in the attached figure. Figure 9 As shown, after successful calibration, the parameters are burned and solidified to ensure the accuracy and reliability of the measurement.

[0078] During the movement of the vehicle equipped with the inertial measurement device, the original pulses of the gyroscope and accelerometer are obtained through multi-stage temperature compensation calculation. After IIR filtering and multi-stage temperature compensation are performed on the 0.5ms original pulses of the gyroscope and accelerometer, the various error parameters of the accelerometer are obtained by using ten-position accelerometer calibration technology.

[0079] Then, after each power outage and power-on of the fiber optic inertial navigation system, after IIR filtering and multi-stage temperature compensation, tool error compensation is performed using acceleration and angular velocity measurements to obtain real-time view velocity increments, view angle increments, and instantaneous angular velocities in the three-axis directions. This is then used to calibrate and compensate the accelerometer quadratic terms to improve navigation accuracy. After that, dual-position Kalman filtering alignment is performed, and finally, high-precision position calculation is achieved through single-axis rotation modulation technology.

[0080] Through experimental testing and comparison, the inertial measurement device of this embodiment is 20% smaller in size and weight than the existing 120-type three-self fiber optic inertial group, while its accuracy is improved by 38%, realizing the function of heterogeneous high-precision lightweight inertial measurement.

[0081] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention. Furthermore, it should be noted that the accompanying drawings are merely illustrative and are not drawn to scale, and should not be construed as limiting the actual scope of protection of the invention.

Claims

1. A high-precision, lightweight, and compact strapdown inertial measurement unit, characterized in that: It includes a cavity structure with a base (1) on its surface, and an optical fiber inertial navigation system body, a shifting mechanism, a locking mechanism and a control mechanism disposed in the cavity structure; The indexing mechanism includes an integrated frame (2) connected to the cavity structure via an outer shaft (5), a platform (3) connected to the integrated frame (2) via an inner shaft (4), an outer shaft torque motor and an outer shaft angle sensor respectively disposed at both ends of the outer shaft (5), and an inner shaft torque motor (8) and an inner shaft angle sensor respectively disposed at both ends of the inner shaft (4); the axes of the inner shaft (4) and the outer shaft (5) are perpendicular to each other and located in the same plane; The fiber optic inertial navigation system includes three fiber optic gyroscopes (6) and three accelerometers (7); the three fiber optic gyroscopes (6) are fixedly mounted on the base (1) along the three axes; the three accelerometers (7) are respectively mounted on the platform (3) along the three axes. The locking mechanism is used to lock and fix the position of the indexing mechanism; The control mechanism is electrically connected to the locking mechanism, the outer shaft torque motor, the inner shaft torque motor (8), the outer shaft angle sensor, the inner shaft angle sensor, three fiber optic gyroscopes (6) and three accelerometers (7), respectively. The control mechanism includes a data acquisition module, an inertial navigation system (INS) calculation module, a spinlock control module, and a communication module. The data acquisition module is used to acquire digital signal data from the accelerometer (7) and the fiber optic gyroscope (6) and transmit them to the inertial navigation system (INS) calculation module. The inertial navigation system (INS) calculation module processes the digital signal data acquired by the data acquisition module and sends control signals to the spinlock control module. The INS includes an accelerometer self-calibration section and a modulation navigation section. The accelerometer self-calibration section is used to solidify the parameter calibration before the carrier runs and to perform calibration and correction during the carrier runs. The modulation navigation section is used to make the error of the fiber optic INS body present a periodic pattern through rotation modulation during the carrier runs, thereby suppressing the impact of error on navigation accuracy. After performing dual-position Kalman filtering alignment, the modulation navigation section performs single-axis rotation modulation. The modulation navigation sequence is 0°→180°→360°→180°→0°, and the rotation stop time, rotation time and stop can be set to achieve high-precision rotation modulation navigation. The rotary lock control module controls and coordinates the operation of the indexing mechanism and the locking mechanism according to the control signal output by the inertial navigation system (INS) calculation module, and cooperates with the INS calculation module to perform rotation modulation and locking. The communication module is used for communication between the inertial navigation system (INS) calculation module and the ground test equipment.

2. The high-precision, lightweight, and compact strapdown inertial measurement device according to claim 1, characterized in that: One of the fiber optic gyroscopes (6) is integrated with the outer shaft (5) and the outer shaft angle sensor.

3. The high-precision, lightweight, and compact strapdown inertial measurement device according to claim 2, characterized in that: The inner axis angle sensor includes an inner axis circular grating (9) and an inner axis grating reading head (10). The inner axis circular grating (9) is fixedly connected to the inner axis (4), and the inner axis grating reading head (10) is correspondingly set on an integrated frame (2) on one side of the inner axis circular grating (9). The outer shaft angle sensor includes an outer shaft circular grating (13) and an outer shaft grating reading head (14). The outer shaft circular grating (13) is fixedly connected to the outer shaft (5), and the outer shaft grating reading head (14) is correspondingly disposed on the base (1) on one side of the outer shaft circular grating (13).

4. A high-precision, lightweight, and compact strapdown inertial measurement device according to claim 3, characterized in that: The locking mechanism adopts a double-end toothed disc engagement locking, and the locking of the indexing mechanism is achieved by controlling the disengagement and engagement of the two toothed discs; The locking mechanism includes a fixed gear plate, a locking seat, a movable gear plate (11), a push rod (12), and two locking motors. The two locking motors, the fixed gear plate, and the locking seat are all mounted on the base (1). The movable gear plate (11) is fixedly mounted on one end of the inner shaft (4) connected to the inner shaft circular grating (9). The push rod (12) is fixedly mounted on the outer wall of the integrated frame (2) connected to the inner shaft torque motor (8). The two locking motors control the fixed gear plate and the locking seat to move in opposite directions along the inner shaft (4) through a worm gear structure, so that the fixed gear plate and the movable gear plate mesh and lock, and the push rod (12) engages and locks with the locking seat.

5. A high-precision, lightweight, and compact strapdown inertial measurement device according to claim 1, characterized in that: The inertial navigation system (INS) solution module can perform IIR filtering on the raw pulses from the 0.5ms fiber optic gyroscope and the raw pulses from the accelerometer acquired in real time by the data acquisition module. Then, the modulation navigation section uses acceleration measurement and angular velocity measurement to perform tool error compensation, and obtains the real-time apparent velocity increment, apparent angle increment and instantaneous angular velocity in the three-axis directions.

6. A high-precision, lightweight, and compact strapdown inertial measurement device according to claim 5, characterized in that: The accelerometer self-calibration section adopts a ten-position accelerometer calibration technique. After IIR filtering, the acceleration components collected during the ten rotations are projected onto each coordinate axis. By establishing a mathematical model that includes accelerometer error parameters, the data collected from multiple positions are processed to obtain various error parameters of the accelerometer, thereby achieving 12-dimensional parameter calibration of the accelerometer. Let the angles between the projection components of the X-axis onto the actual position coordinate axes and X1, Z1, and Y1 be A, B, and C, respectively. The calibration algorithm used in the ten-position addition calibration technique is as follows: ; In the formula The gravitational acceleration at the calibration position, The component of the accelerometer on the platform in the X-axis direction, The component of the accelerometer on the platform in the Y-axis direction, The component of the accelerometer on the platform in the Z-axis direction, The scaling factor for the corresponding X, Y, or Z axis measurement channel; The installation error of the acceleration input shaft around the body shaft; This corresponds to the zero offset value of the X, Y, or Z axis axial measurement channel.

7. A high-precision, lightweight, and compact strapdown inertial measurement device according to claim 5, characterized in that: The modulation navigation section reads the pre-calibrated quadratic error parameters stored in the device when powered on, and compensates the digital signal data acquired by the data acquisition module according to the quadratic model and the quadratic error parameters, so as to reduce the impact of the quadratic error on the navigation accuracy.

8. A high-precision, lightweight, and compact strapdown inertial measurement device according to claim 1, characterized in that: The inertial navigation system (INS) calculation module employs multi-level temperature compensation technology, using a temperature compensation scheme based on constant-temperature fiber optic gyroscopes and accelerometers to achieve full parameter compensation.

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