High-precision light-small strapdown inertial measurement device

Abstract

The invention relates to an inertial measurement device, aims to solve the technical problems that an existing inertial measurement device is large in error, large in size and weight and difficult to realize self-calibration and regular maintenance functions anytime and anywhere, and provides a high-precision light-small strapdown inertial measurement device. Three high-precision fiber-optic gyroscopes are fixedly installed on an inertial measurement unit base in the three-axis direction, a double-axis indexing mechanism is adopted, the fiber-optic gyroscopes are kept immobile, only a table body provided with accelerometers in the three-axis direction needs to be rotated, and the self-calibration function is achieved through the ten-position accelerometer calibration technology. The influence of the error of the optical fiber inertial measurement unit body on the navigation precision is inhibited through single-axis rotation modulation, the self-calibration precision and efficiency are improved, the regular maintenance of the inertial measurement device is finally realized, the requirement of high-precision navigation in the carrier movement process is met, and the mechanical structure greatly reduces the volume and weight of the inertial measurement device and realizes light weight.

Description

Technical Field

[0001] The invention relates to an inertial measurement device, in particular to a high-precision, lightweight and small-sized strapdown inertial measurement device. Background Art

[0002] An inertial measurement device is a device that uses the principle of inertia to measure the motion state of an object. It uses accelerometers and gyroscopes to measure the acceleration and angular velocity of an object in real time, and then processes this data using algorithms such as integration to infer motion state parameters such as the object's position, velocity, and attitude.

[0003] However, as the demand for refinement and high precision of existing navigation systems continues to increase, the existing inertial measurement devices have large errors and their performance can no longer meet the new requirements. At the same time, the existing inertial measurement devices also have the defects of large size and weight. Moreover, after being delivered to users, pure strapdown inertial measurement devices need to be frequently returned to the factory for calibration and regular maintenance, which causes inconvenience to users. Summary of the Invention

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

[0005] To achieve the above objectives, the present invention provides the following technical solutions:

[0006] A high-precision, lightweight and compact strapdown inertial measurement unit, which is special in that:

[0007] It includes a cavity structure with a base provided on the surface, and an optical fiber inertial group body, a transfer mechanism, a locking mechanism and a control mechanism provided in the cavity structure;

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

[0009] The fiber optic inertial group body includes three fiber optic gyroscopes and three accelerometers; the three fiber optic gyroscopes are fixedly arranged on the base along the three axis directions; the three accelerometers are respectively arranged on the platform along the three axis directions;

[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 respectively.

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

[0013] Furthermore, the inner shaft angle sensor includes an inner shaft circular grating and an inner shaft grating reading head, the inner shaft circular grating is fixedly connected to the inner shaft, and the inner shaft grating reading head is correspondingly arranged on an integrated frame on one side of the inner shaft circular grating;

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

[0015] Furthermore, the locking mechanism adopts double-end gear disc engagement locking, and the locking of the indexing mechanism is achieved by controlling the disengagement and engagement of the two gear 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 arranged on the base. The movable gear plate is fixedly arranged on one end of the inner shaft connected to the inner shaft circular grating. The push rod is fixedly installed on the outer side wall of the integrated frame connected to the inner shaft torque motor, and the two locking motors respectively control the fixed gear plate and the locking seat to move toward each other along the inner shaft direction through the worm gear structure, so that the fixed gear plate is engaged and locked with the movable gear plate, and the push rod is engaged and locked with the locking seat.

[0017] Furthermore, the control mechanism includes a data acquisition module, an inertial group solution module, a rotation lock control module and a communication module;

[0018] The data acquisition module is used to collect digital signal data from the accelerometer and the fiber optic gyroscope and transmit it to the inertial group solution module;

[0019] The inertial group solution module processes the digital signal data collected by the data acquisition module and then sends a control signal to the rotation lock control module. It includes an accelerometer self-calibration part and a modulation navigation part. The accelerometer self-calibration part is used to achieve parameter calibration and solidification before the carrier runs and perform calibration correction during the carrier operation. The modulation navigation part is used to make the error of the fiber optic inertial group body present a periodic regularity through rotation modulation during the carrier operation, thereby suppressing the influence of the error on the 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 group solving module, and cooperates with the inertial group solving module to perform rotation modulation and locking;

[0021] The communication module is used for communication between the inertial group solution module and the ground test equipment.

[0022] Furthermore, the inertial group solution module can perform IIR filtering on the original pulses of the 0.5ms fiber optic gyroscope and the original pulses of the accelerometer collected in real time by the data acquisition module.

[0023] Furthermore, the inertial group solution module adopts a multi-level temperature compensation technology, and realizes full parameter compensation based on the temperature compensation scheme of the constant temperature fiber optic gyroscope and accelerometer.

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

[0025] Furthermore, the accelerometer self-calibration part adopts a ten-position table calibration technology. After performing IIR filtering, the acceleration components collected during the ten rotations are projected onto each coordinate axis. By establishing a mathematical model containing the accelerometer error parameters, the data collected at multiple positions are processed and the various error parameters of the accelerometer are obtained, thereby realizing 12-dimensional parameter calibration of the accelerometer;

[0026] Assume that the angles between the projection component of the X-axis on the actual position coordinate axis and X1, Z1, and Y1 are A, B, and C respectively. The calibration algorithm used in the ten-position plus table calibration technology is as follows:

[0027]

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

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

[0030] Furthermore, the modulation navigation part performs single-axis rotation modulation after dual-position Kalman filter alignment, and the modulation navigation order is single-axis 0°→180°→360°→180°→0°, and the rotation and 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) The inertial measurement device of the present invention mounts the accelerometer on the platform along three axes, and is fixedly connected to the integrated frame through the inner axis. The inner and outer axes are linked in two stages with the base on which the outer axis is mounted. This not only improves the space utilization of the platform, but also cooperates with the inertial group solution module to realize the rotation calibration compensation of the accelerometer, so that the present invention has the functions of self-calibration and rotation modulation, thereby improving the navigation accuracy.

[0033] (2) The inertial measurement device of the present invention fixes three fiber optic gyroscopes on a base along three axes, realizing physical heterogeneity of the inertial instrument. The gyroscopes can be kept stationary during the inertial measurement process, and only the inner and outer axes are rotated to realize modulation navigation, thereby reducing the source of error and simplifying the system structure. In addition, one of the fiber optic gyroscopes is integrated with the outer axis and the outer axis angle sensor, further improving space utilization and meeting the requirements of lightness and small size.

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

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

[0036] (5) The inertial measurement device in the present invention performs high-precision navigation by real-time compensation of the quadratic term of the accelerometer, and can operate stably under multi-physical field conditions. In addition, multi-stage temperature compensation technology is used in the early stage to realize inertial navigation under a wide temperature range of the system, so that the present invention can meet the needs of future carrier systems to maintain long-term high-precision inertial measurement. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0038] Figure 2 Schematic diagram of the partial structure of the inner shaft system of the integrated frame in an embodiment of the present invention;

[0039] Figure 3 Schematic diagram of the integrated structure of the fiber optic gyroscope, the external shaft, and the external shaft angle sensor in an embodiment of the present invention;

[0040] Figure 4 1 is a principle block diagram of a data acquisition module in an embodiment of the present invention;

[0041] Figure 5 1 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 navigation azimuth error curve diagram after compensating for the quadratic acceleration error in an embodiment of the present invention;

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

[0044] Figure 8 This is a functional block diagram of a spin lock control module in an embodiment of a high-precision, lightweight, and compact strapdown inertial measurement system of the present invention;

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

[0046] In the figure: 1-base, 2-integrated frame, 3-platform, 4-inner axis, 5-outer axis, 6-fiber optic gyroscope, 7-accelerometer, 8-inner axis torque motor, 9-inner axis circular grating, 10-inner axis grating reading head, 11-moving gear disc, 12-top rod, 13-outer axis circular grating, 14-outer axis grating reading head. DETAILED DESCRIPTION

[0047] The present invention will be further described in detail below with reference to specific embodiments. Please note that the embodiments are intended to explain the present invention rather than to limit it.

[0048] See attached Figure 1 As shown in FIG, this embodiment provides a high-precision, lightweight and small-sized strapdown inertial measurement device, comprising a cavity structure with a base 1 provided on the surface, and three high-precision 140 fiber optic gyroscopes 6 are fixedly provided on the three-axis direction surface of the base 1; an integrated frame 2 is provided in the cavity structure, and a body 3 is connected to the integrated frame 2 through an inner shaft 4, as shown in FIG. Figure 2As shown, the platform 3 is respectively provided with three positioning surfaces along the three-axis directions, and accelerometers 7 are installed on the positioning surfaces, and one end of the inner shaft 4 is fixedly connected to the output end of the inner shaft torque motor 8, and the other end is fixedly connected to the inner shaft circular grating 9 and the shaft end of the inner shaft 4 is fixedly connected to the movable gear disc 11, and the side of the integrated frame 2 away from the movable gear disc 11 is fixedly connected to the push rod 12, and the fixed gear disc and the locking seat provided on the base 1 are controlled by the corresponding locking motor and the worm gear structure to move toward each other along the direction of the inner shaft 4, so that the movable gear disc 11 is engaged with the fixed gear disc, and the push rod 6 is engaged with the locking seat to achieve locking of the position of the integrated frame; and as shown in the attached figure 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 through the external shaft 5, and the external shaft torque motor is arranged on the base 1. The other end wall is fixedly connected to the external shaft circular grating 13 in turn through the external shaft 5, and is rotatably connected to the base 1; the integrated frame 2 is also provided with two inner shaft grating reading heads 10 and outer shaft grating reading heads 14 corresponding to the inner shaft circular grating 9 and the outer shaft circular grating 13 respectively, which can convert the measured angular displacement into an electrical signal and transmit it to the control mechanism.

[0049] In order to reduce the volume and weight of the inertial measurement device, the platform 3 on which the accelerometer 7 is installed is integrated with the inner shaft 4, so that the rotation radius is greatly reduced, and the weight and volume of the platform 3 are reduced.

[0050] The worm gear structure includes a turbine and a worm rod, which is controlled by a locking motor and drives the worm rod to perform linear motion, thereby controlling the rotation direction of the turbine. The turbine is threadedly connected to the fixed gear plate or the locking seat through a threaded rod, and positioning sliding guide rails are provided on both sides of the fixed gear plate, so that the rotation of the turbine drives the rotation of the threaded rod. The fixed gear plate and the locking seat connected to the threaded rod move toward each other along the direction of the inner shaft 4 under the directional action of the positioning sliding guide rail. Therefore, it is only necessary to change the rotation direction of the turbine by the locking motor to achieve the locking and separation of the indexing mechanism and the base.

[0051] A control mechanism is installed on the base 13, which 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 movable gear plate 11 and the fixed gear plate, and the push rod 12 and the locking seat to be locked and fixed.

[0052] The control mechanism in this embodiment specifically includes a data acquisition module, an inertial group solution module, a rotary lock control module and a communication module; the rotary lock control module coordinates the operation of the transfer mechanism and the locking mechanism according to the control signal output by the inertial group solution module; the communication module is used for communication with ground test equipment.

[0053] Data acquisition module as attached Figure 4As shown in the figure (the table in the figure is the accelerometer), the data acquisition module includes an analog-to-digital conversion circuit and a gyro demodulation circuit, and adopts ten-position static data acquisition to collect digital signal data of the accelerometer and the fiber optic gyroscope and transmit it to the inertial group solution module. The inertial group solution module calibrates the accelerometer. The calibration method adopts the ten-position table calibration technology as shown in the attached figure. Figure 5 As shown, the details are as follows:

[0054] The acceleration components collected during the ten rotations are projected onto each coordinate axis. A mathematical model containing the accelerometer error parameters is established. The data collected at multiple positions are processed to obtain the various error parameters of the accelerometer. Assume that the angles between the projection component of the X-axis on the actual position coordinate axis of the inertial group and the X1, Z1, and Y1 are A, B, and C respectively. The ten-position calibration algorithm is as follows:

[0055]

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

[0057] The inertial group solution module can collect the original pulses of the 0.5ms fiber optic gyroscope and the original pulses of the accelerometer in real time, perform IIR filtering, and then perform multi-level temperature compensation. It then uses acceleration measurement and angular velocity measurement to compensate for tool errors, and obtains real-time viewing angle velocity increment, viewing angle increment and instantaneous angular velocity in the three-axis direction.

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

[0059]

[0060] Where: T s is the sampling period, unit is s; N ax 、N ay 、N az The apparent acceleration increments output by the X, Y, and Z axis acceleration measurement channels, in ^ / T s ;K 0x , K 0y , K 0zThey are the zero offset values ​​of the X, Y and Z axis measurement channels, in ^ / s; K 1x , K 1y , K 1z The scale factors of the X-axis, Y-axis, and Z-axis measurement channels, in ^ / (g·s); K yx , K zx , K xy , K zy , K xz , K yz J Y Acceleration input axis around the body axis Y, Z, J X Acceleration input axis around the body axis X, Z, J Z Installation error of the acceleration input shaft around the body axes X and Y, unit: ^ / (g·s).

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

[0062]

[0063] Where: N ωx 、N ωy 、N ωz The increment of the angular velocity output by the gyroscope in the X, Y and Z channels, in units of ^ / T s ;E 0x 、E 0y 、E 0z are the constant drift of the gyro in X, Y and Z directions, in ^ / s; E 1x 、E 1y 、E 1z Gyro G X , G Y and G Z The scale factor of the unit is ^ / ";E xy 、E yx 、E xz 、E zx 、、E zy 、E yz G X Input shaft around the body axis Y, Z, G Y Input shaft around the body axis X, Z, G Z Input the installation error of the shaft around the X and Y axes of the body, in units of ^ / ", and convert the angular increment after the tool error into angular velocity by dividing it by the sampling time. This allows real-time measurement of angular velocity.

[0064] The input and output characteristics of the accelerometer are usually described by algebraic equations. The most common method is the quadratic equation, that is, the quadratic term model:

[0065]

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

[0067] By calibrating and compensating the quadratic term of acceleration, the quadratic term error of the east accelerometer is K2Y=-0.3*10 -6 g / g 2 ; The quadratic term of the north accelerometer is K2Z=0.2*10 -6 g / g 2 ; as attached Figure 6 As shown, the quadratic term of the celestial accelerometer is K2X=0.2*10 -6 g / g 2 , and then use single-axis rotation modulation technology to control the rotation and locking of the inner and outer axes, and perform real-time high-precision position calculation, as shown in the attached Figure 7 As shown, the modulation navigation order is single-axis 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 IAR solution module also establishes the relationship between the angular rate and acceleration measurement information output by the IAR and temperature changes. The goal is to achieve full temperature consistency of the angular rate and acceleration measurement information output by the IAR. Temperature compensation is achieved by designing a fiber-optic IAR temperature modeling test environment and test methods, as follows:

[0069] S1: Temperature hysteresis test: perform low temperature → high temperature → low temperature test according to product specification requirements 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: Calibrate the tool error parameters using system-level calibration tests at multiple temperature points. The relationship between temperature and inertial group output is calculated based on the test data at each temperature point, and the temperature compensation model is solved.

[0072] S4: The relationship between the temperature change rate and the accelerometer output is obtained through static testing at high temperature, low temperature, and room temperature, and a temperature change-acceleration zero compensation model is obtained;

[0073] S5: Calculate temperature compensation parameters;

[0074] S6: Use the obtained parameters to substitute into the preset model to compensate for the error of the inertial group and verify the compensated results.

[0075] Twist lock control module as attached Figure 8 As shown in the figure, the CPU module composed of DSP, FPGA and corresponding peripheral circuits serves as the hardware platform for driving and controlling the indexing mechanism and the locking mechanism. It is electrically connected to the inertial group solution module, receives the modulation signal from the inertial group solution module, and controls the rotation angle and speed of the inner and outer frame bearings according to the set modulation navigation sequence, so that the error parameters are modulated into periodic signals, which are compensated and corrected to improve the 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 group are calibrated using 19 positions as shown in the attached figure. Figure 9 As shown in the figure, after successful calibration, the parameters are triggered to be 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-level temperature compensation calculation. After IIR filtering and multi-level temperature compensation are performed on the original pulses of the 0.5ms gyroscope and accelerometer, the ten-position addition table calibration technology is used to obtain the various error parameters of the accelerometer.

[0079] Each time the fiber-optic inertial navigation system is powered off and back on again, after IIR filtering and multi-stage temperature compensation, acceleration and angular velocity measurements are used to compensate for tool errors, obtaining real-time three-axis visual velocity increments, visual angle increments, and instantaneous angular velocity. Calibration compensation of the quadratic terms of the accelerometer is then performed to improve navigation accuracy. Dual-position Kalman filter alignment is then performed, and finally, high-precision position solution is achieved through single-axis rotation modulation technology.

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

[0081] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be subject to various modifications and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention. In addition, it should be noted that the drawings are only for example and are not drawn according to the conditions of equal scale, and should not be used as a limitation on the actual scope of protection required by the present invention.

Claims

1. A high-precision, lightweight and compact strapdown inertial measurement unit, characterized by: It comprises a cavity structure with a base (1) arranged on the surface, and an optical fiber inertial group body, a transfer mechanism, a locking mechanism and a control mechanism arranged in the cavity structure; The indexing mechanism comprises an integrated frame (2) connected to the cavity structure via an external shaft (5), a platform (3) connected to the integrated frame (2) via an internal shaft (4), an external shaft torque motor and an external shaft angle sensor respectively arranged at both ends of the external shaft (5), and an internal shaft torque motor (8) and an internal shaft angle sensor respectively arranged at both ends of the internal shaft (4); the axes of the internal shaft (4) and the external shaft (5) are perpendicular to each other and are located in the same plane; The fiber optic inertial group body comprises three fiber optic gyroscopes (6) and three accelerometers (7); the three fiber optic gyroscopes (6) are fixedly arranged on the base (1) along three axis directions; the three accelerometers (7) are respectively arranged on the platform (3) along three axis directions; 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.

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

3. The high-precision, lightweight, and compact strapdown inertial measurement device according to claim 2, wherein: The inner shaft angle sensor comprises an inner shaft circular grating (9) and an inner shaft grating reading head (10), wherein the inner shaft circular grating (9) is fixedly connected to the inner shaft (4), and the inner shaft grating reading head (10) is correspondingly arranged on an integrated frame (2) on one side of the inner shaft circular grating (9); The external shaft angle sensor comprises an external shaft circular grating (13) and an external shaft grating reading head (14). The external shaft circular grating (13) is fixedly connected to the external shaft (5), and the external shaft grating reading head (14) is correspondingly arranged on a base (1) on one side of the external shaft circular grating (13).

4. The high-precision, lightweight and compact strapdown inertial measurement unit according to claim 3, characterized in that: The locking mechanism adopts double-end gear disc engagement and locking, and the locking of the indexing mechanism is achieved by controlling the disengagement and engagement of the two gear discs; The locking mechanism comprises a fixed toothed disc, a locking seat, a movable toothed disc (11), a push rod (12) and two locking motors. The two locking motors, the fixed toothed disc and the locking seat are all arranged on the base (1). The movable toothed disc (11) is fixedly arranged on one end of the inner shaft (4) connected to the inner shaft circular grating (9). The push rod (12) is fixedly installed on the outer side wall of the integrated frame (2) connected to the inner shaft torque motor (8). The two locking motors respectively control the fixed toothed disc and the locking seat to move toward each other along the direction of the inner shaft (4) through a worm gear structure, so that the fixed toothed disc and the movable toothed disc are engaged and locked, and the push rod (12) is engaged and locked with the locking seat.

5. The high-precision, lightweight and compact strapdown inertial measurement device according to claim 1, characterized in that: The control mechanism includes a data acquisition module, an inertial group solution module, a twist lock control module and a communication module; The data acquisition module is used to collect digital signal data from the accelerometer (7) and the fiber optic gyroscope (6) and transmit the data to the inertial group solution module; The inertial group solution module processes the digital signal data collected by the data acquisition module and then sends a control signal to the rotation lock control module. It includes an accelerometer self-calibration part and a modulation navigation part. The accelerometer self-calibration part is used to achieve parameter calibration and solidification before the carrier runs and perform calibration correction during the carrier operation. The modulation navigation part is used to make the error of the fiber optic inertial group body present a periodic regularity through rotation modulation during the carrier operation, thereby suppressing the influence of the error on the navigation accuracy. 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 group solving module, and cooperates with the inertial group solving module to perform rotation modulation and locking; The communication module is used for communication between the inertial group solution module and the ground test equipment.

6. The high-precision, lightweight, and compact strapdown inertial measurement device according to claim 5, characterized in that: The inertial group solution module can perform IIR filtering on the 0.5ms raw pulses of the fiber optic gyroscope and the raw pulses of the accelerometer collected in real time by the data acquisition module. The modulation navigation part then uses acceleration measurement and angular velocity measurement to compensate for tool errors, obtaining real-time apparent velocity increments, apparent angle increments, and instantaneous angular velocity in the three-axis directions.

7. The high-precision, lightweight, and compact strapdown inertial measurement device according to claim 6, characterized in that: The accelerometer self-calibration part adopts the ten-position table calibration technology. After performing IIR filtering, the acceleration components collected during the ten rotations are projected onto each coordinate axis. By establishing a mathematical model containing the accelerometer error parameters, the data collected at multiple positions are processed and the various error parameters of the accelerometer are solved, thereby achieving 12-dimensional parameter calibration of the accelerometer. Assume that the angles between the projection component of the X-axis on the actual position coordinate axis and X1, Z1, and Y1 are A, B, and C respectively. The calibration algorithm used in the ten-position plus table calibration technology is as follows: Where g is the gravity acceleration at the calibration position, a tx* is the component of the accelerometer on the platform in the X-axis direction, a ty* is the component of the accelerometer on the platform in the Y-axis direction, a tz* is the component of the accelerometer on the platform in the Z-axis direction, A m A is the scale factor corresponding to the X, Y or Z axis measurement channel; mj is the installation error of the acceleration input shaft around the body axis; a m0 It is the zero offset value of the axial measurement channel corresponding to the X, Y or Z axis.

8. The high-precision, lightweight, and compact strapdown inertial measurement device according to claim 6, characterized in that: The modulation navigation part reads the pre-calibrated quadratic error parameters solidified in the device when powered on, and compensates the digital signal data collected by the data acquisition module according to the table-added quadratic model and the quadratic error parameters to reduce the impact of the quadratic error on navigation accuracy.

9. The high-precision, lightweight and compact strapdown inertial measurement device according to claim 5, characterized in that: The modulation navigation part performs single-axis rotation modulation after dual-position Kalman filter alignment. The modulation navigation order is single-axis 0°→180°→360°→180°→0°. The rotation and stop time, rotation time and stop can be set to achieve high-precision rotation modulation navigation.

10. The high-precision, lightweight and compact strapdown inertial measurement device according to claim 5, characterized in that: The inertial group solution module adopts multi-level temperature compensation technology and realizes full parameter compensation based on the temperature compensation scheme of the constant temperature fiber optic gyroscope and accelerometer.

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