A damping shock absorber and a self-absorbing vibration mechanical jitter laser gyro inertial measurement unit

Abstract

The present invention discloses a damping shock absorber and a self-absorbing vibration mechanical jitter laser gyro inertial measurement unit. The damping shock absorber includes a cavity seat, a resonance mechanism and a sealing cover; the sealing cover is detachably connected to the cavity seat, and a closed resonance cavity is formed between the cavity seat and the sealing cover; the resonance mechanism is arranged in the resonance cavity, and one end of the resonance mechanism is detachably connected to the cavity seat, and there is a gap between the other end and the sealing cover to generate a dynamic vibration absorption effect through the angular vibration resonance of the resonance mechanism; damping oil is filled between the resonance mechanism and the cavity wall of the resonance cavity to generate an angular vibration damping effect through the damping oil. The present invention is applied to the field of laser gyro inertial navigation, can reduce vibration and noise of the laser gyro inertial navigation system without bringing additional adverse effects to it, and finally can improve the performance of the laser gyro inertial navigation system and broaden the application scenarios of the laser gyro inertial navigation system.

Description

Technical Field

[0001] The present invention relates to the technical field of laser gyro inertial navigation, and particularly to a damping shock absorber and a self-absorbing vibration mechanical dithering laser gyro inertial measurement unit. Background Art

[0002] A laser gyro inertial navigation system is a fully autonomous navigation system. It can rely solely on the information of its internal sensors (laser gyroscopes and accelerometers) for real-time navigation calculation without depending on any external information input, and can output various navigation information such as the real-time position, speed, and attitude of the carrier on which it is installed. The laser gyro inertial navigation system has many advantages such as autonomy, concealment, and reliability, and is widely used in the military field and the civilian market to provide highly reliable navigation information for mobile carriers such as airplanes, missiles, artillery, vehicles, ships, and submarines.

[0003] The core device of a laser gyro inertial navigation system is a laser gyroscope. There are various types of laser gyroscopes, such as mechanical dithering laser gyroscopes and four-frequency differential laser gyroscopes. Currently, the most widely used laser gyroscope in inertial navigation systems is the mechanical dithering laser gyroscope. A mechanical dithering laser gyroscope installs a dithering mechanism (referred to as a dither wheel) in the middle of the laser gyroscope. During operation, the high-frequency dithering of the dither wheel drives the gyroscope cavity to dither, that is, the alternating mechanical angular vibration is used to offset the laser gyroscope from the locked region, thereby overcoming the locked-in error effect of the laser gyroscope and greatly improving the accuracy of the laser gyroscope. It has the advantages of high accuracy, simple structure, and good reliability.

[0004] An inertial measurement unit (IMU) is the core component of a laser gyro inertial navigation system. A typical laser gyro inertial measurement unit consists of three laser gyroscopes, three accelerometers, a mechanical mounting body, and several rubber shock absorbers. The structure of the mounting body ensures that the sensitive axes of the three laser gyroscopes are arranged along three orthogonal directions. The body is connected to the external inertial navigation system structure through rubber shock absorbers. Since there is high-frequency dithering during the operation of a mechanical dithering laser gyroscope, in order to overcome the influence of dithering on the system accuracy, generally two measures are taken: The first is that the dithering frequencies of the three laser gyroscopes installed on the same set of IMU should be staggered from each other, generally separated by more than 30 Hz, to ensure that their ditherings do not interfere with each other; the second is to isolate the mounting body from the external inertial navigation system structure through rubber shock absorbers, thereby reducing the influence of the laser gyro dithering on external devices and also reducing the influence of external environmental changes on dithering.

[0005] After using rubber shock absorbers to reduce the vibration of the IMU, the application requirements of the ring laser gyro inertial navigation system can be met in most cases. However, there is always a part of the vibration energy transmitted in the form of sound noise and mechanical vibration. With the increasing requirements for the accuracy performance and operating environmental conditions of the ring laser gyro inertial navigation system, these transmitted sound noise and mechanical vibration will cause many problems in many application scenarios. For example, the leaked sound noise is not suitable in some noise-sensitive application scenarios such as submarines, and the mechanical vibration transmitted to the system base will interfere with the carrier's precision measurement equipment or the guidance and control system. In particular, the vibration of the body will cause vibration coupling between the three gyros, resulting in an additional conical error effect. For example, in a high-precision rotation modulation ring laser gyro inertial navigation system, the inertial measurement unit rotates continuously in space. When there is mechanical vibration leakage, it will inevitably lead to vibration anisotropy in different rotation orientations, that is, the conical error effects caused by the vibration angular velocity in different rotation orientations are different, thus seriously affecting the improvement of the inertial navigation system accuracy and the long-term stability of the navigation performance.

[0006] In order to further improve the performance of the mechanically dithered ring laser gyro inertial navigation system, it is necessary to reduce the vibration energy leakage of its inertial measurement unit. Reducing the resonant frequency of the rubber shock absorber is a method to reduce vibration leakage. However, when the resonant frequency becomes lower, the stiffness of the rubber shock absorber will also decrease synchronously, not only reducing the attitude output bandwidth of the inertial navigation system, but also increasing the attitude deformation of the IMU relative to the installation housing when the carrier is moving, thus reducing the output accuracy of the inertial navigation system attitude. Designing a secondary shock absorption device outside the inertial measurement unit can also reduce vibration leakage, but it will inevitably lead to an increase in the system volume and weight and a decrease in the attitude output accuracy. In addition, a counterweight type ring laser gyro dithering mechanism (also known as an anti-recoil torque dithering wheel) has been mentioned in domestic and foreign literature, which can eliminate the reaction force of the gyro dithering on the installation body, thus greatly reducing the vibration of the IMU body. However, this counterweight type dithering mechanism has a complex structure, a large volume and weight, and its reliability and stability are not as good as the existing all-metal structure dithering wheel. The counterweight type dithering mechanism has never been applied in engineering at home and abroad and is generally considered a dithering scheme with no future.

[0007] Since the existing measures to reduce the vibration of the mechanically dithered ring laser gyro inertial navigation system always have various problems, the present invention provides a damping shock absorber and a self-absorbing vibration mechanically dithered ring laser gyro inertial measurement unit. This self-absorbing vibration mechanically dithered ring laser gyro inertial measurement unit is equipped with three damping shock absorbers of the present invention, which can significantly reduce the vibration and noise of the inertial measurement unit without increasing the weight and volume of the inertial navigation system and without reducing the attitude output accuracy of the inertial navigation system, thereby improving the performance of the mechanically dithered ring laser gyro inertial navigation system and meeting the requirements of more inertial navigation application scenarios. Summary of the Invention

[0008] In view of the problems of mechanical vibration and noise of the inertial measurement unit in the existing mechanical dither laser gyro inertial navigation system, the present invention provides a damping shock absorber and a self-absorbing vibration mechanical dither laser gyro inertial measurement unit, which can effectively reduce the vibration and noise of the mechanical dither laser gyro inertial measurement unit during operation, thereby further improving the performance of the corresponding laser gyro inertial navigation system.

[0009] To achieve the above object, the present invention provides a damping shock absorber, which includes a cavity seat, a resonance mechanism and a sealing cover;

[0010] The sealing cover is detachably connected to the cavity seat, and a closed resonance cavity is formed between the cavity seat and the sealing cover;

[0011] The resonance mechanism is arranged in the resonance cavity, and one end of the resonance mechanism is detachably connected to the cavity seat, and there is a gap between the other end and the sealing cover to generate a dynamic vibration absorption effect through the angular vibration resonance of the resonance mechanism;

[0012] Damping oil is filled between the resonance mechanism and the cavity wall of the resonance cavity to generate an angular vibration damping effect through the damping oil.

[0013] In one embodiment, the resonance mechanism includes a resonance ring and an adjustment ring;

[0014] One end of the resonance ring is detachably connected to the cavity seat, and there is a gap between the other end and the sealing cover to generate a dynamic vibration absorption effect through the angular vibration resonance of the resonance ring;

[0015] The adjustment ring is detachably sleeved on the resonance ring to adjust the resonance frequency of the resonance ring to be consistent with the angular frequency to be absorbed.

[0016] In one embodiment, the resonance ring includes a central block and an annular body with a rotating body structure;

[0017] The central block is located at the inner ring center of the annular body, and the side wall of the central block is connected to the inner ring wall of the annular body through a plurality of spokes evenly distributed in the circumferential direction to change the resonance angular vibration frequency of the resonance ring by designing the spokes with different thicknesses.

[0018] In one embodiment, at least one first connection block is provided on the cavity seat, and a first threaded hole is provided on the first connection block;

[0019] At least one second connection block is provided between the side wall of the central block and the inner ring wall of the annular body, and a first through hole is provided on the second connection block;

[0020] The first connecting blocks and the second connecting blocks are in one-to-one correspondence, and the first threaded holes and the corresponding first through holes are coaxial.

[0021] In one embodiment, the side part of the annular body is a stepped structure that is narrower at the top and wider at the bottom, and the wider end of the annular body is connected to the cavity seat;

[0022] A plurality of second threaded holes are circumferentially and spacedly provided on the bottom wall of the stepped structure, and a plurality of second through holes corresponding to the second threaded holes one by one are provided on the adjusting ring.

[0023] In one embodiment, a convex structure is provided at a position around the second threaded hole on the bottom wall of the stepped structure, so that there is a gap between the adjusting ring and the bottom wall of the stepped structure.

[0024] In one embodiment, a plurality of third threaded holes are circumferentially and spacedly provided at a position near the edge of the cavity seat, and a plurality of third through holes corresponding to the third threaded holes one by one are provided on the sealing cover;

[0025] A sealing rubber ring is provided on the mating surface between the cavity seat and the sealing cover.

[0026] In one embodiment, a plurality of fourth through holes are circumferentially and spacedly provided at a position near the edge of the cavity seat for mounting the cavity seat on an inertial measurement unit.

[0027] To achieve the above object, the present invention further provides a self-absorbing vibration mechanical jitter laser gyro inertial measurement unit, including a mounting body, an accelerometer assembly, a rubber shock absorber, and three laser gyros;

[0028] The accelerometer assembly is fixedly connected to the mounting body, the rubber shock absorbers are arranged at symmetric positions around the mounting body, and the three laser gyros are respectively arranged on three orthogonal side surfaces of the mounting body;

[0029] It further includes three of the above damping shock absorbers, and the three damping shock absorbers are respectively arranged on the other three orthogonal side surfaces of the mounting body.

[0030] In one embodiment, the frequencies and directions of the resonant angular velocities of the three damping shock absorbers are the same as the frequencies and directions of the jitter angular velocities of the laser gyros mounted on the opposite side surfaces of the mounting body.

[0031] A damping shock absorber and a self-absorbing vibration mechanical jitter laser gyro inertial measurement unit provided by the present invention can significantly reduce the angular vibration of the inertial measurement unit body after the damping shock absorber designed by the present invention is installed on the self-absorbing vibration mechanical jitter laser gyro inertial measurement unit. Compared with the existing method, the present invention does not change the structure of the dither wheel of the laser gyro and has no impact on the performance of the laser gyro. Moreover, in the self-absorbing vibration mechanical jitter laser gyro inertial measurement unit of the present invention, the damping shock absorber is installed on the remaining three sides of the inertial measurement unit installation body where no laser gyro is installed among the six sides. Through reasonable design, it will not cause an increase in the size and weight of the inertial measurement unit, nor will it change the original damping structure of the inertial measurement unit, and has no impact on the attitude accuracy of the inertial navigation system. Therefore, while reducing the vibration and noise of the laser gyro inertial navigation system, the present invention will not bring additional disadvantages, and ultimately will improve the performance of the laser gyro inertial navigation system and broaden the application scenarios of the laser gyro inertial navigation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0033] Figure 1 Isometric view of the damping shock absorber in Embodiment 1 of the present invention;

[0034] Figure 2 Exploded view of the damping shock absorber in Embodiment 1 of the present invention;

[0035] Figure 3 Cross-sectional view of the damping shock absorber in Embodiment 1 of the present invention;

[0036] Figure 4 Isometric view of the cavity seat in Embodiment 1 of the present invention;

[0037] Figure 5 Isometric view of the resonant ring in Embodiment 1 of the present invention;

[0038] Figure 6 Isometric view of the adjusting ring in Embodiment 1 of the present invention;

[0039] Figure 7 Isometric view of the sealing cover in Embodiment 1 of the present invention;

[0040] Figure 8 Schematic structural diagram of a traditional mechanical jitter laser gyro inertial measurement unit;

[0041] Figure 9This is a schematic structural diagram of the mechanical dither laser gyro inertial measurement unit in Embodiment 2 of the present invention.

[0042] Reference numerals in Embodiment 1:

[0043] Cavity base 1, fourth through-hole 101, third threaded hole 102, first connection block 103, first threaded hole 104;

[0044] Sealing cover 2, support feet 201, third through-hole 202;

[0045] Resonant ring 3, spokes 301, central block 302, annular body 303, second connection block 304, first through-hole 305, second threaded hole 306, raised structure 307;

[0046] Adjusting ring 4, second through-hole 401;

[0047] Damping oil 5, resonant cavity 6, sealing rubber ring 7.

[0048] Reference numerals in Embodiment 2:

[0049] Mounting body 8, accelerometer assembly 9, rubber shock absorber 10;

[0050] Laser gyros 11, 12, 13;

[0051] Damping shock absorbers 14, 15, 16.

[0052] The realization of the object, functional features and advantages of the present invention will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0053] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0054] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0055] In addition, in the present invention, descriptions such as "first", "second", etc. are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0056] In the present invention, unless otherwise clearly specified and defined, terms such as "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection, a physical connection or a wireless communication connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0057] In addition, the technical solutions between various embodiments of the present invention can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0058] Embodiment 1

[0059] As Figures 1-3 shown is a damping shock absorber disclosed in this embodiment, which is mainly applied to a self-absorbing vibration mechanical jitter laser gyro inertial measurement unit to solve the problems of mechanical vibration and noise of the inertial measurement unit in a mechanical jitter laser gyro inertial navigation system, while not changing the size and weight of the inertial measurement unit and not changing the original shock absorption structure of the inertial measurement unit, and having no impact on the attitude accuracy of the inertial navigation system.

[0060] Specifically, the damping shock absorber includes a cavity seat 1, a resonance mechanism, a sealing cover 2 and damping oil 5, and the resonance mechanism is composed of a resonance ring 3 and an adjustment ring 4.

[0061] Refer to Figure 4 , the cavity seat 1 is a quadrilateral block structure made of metal, and a plurality of fourth through holes 101 are respectively arranged at four corner positions thereof, for installing the damping shock absorber onto the structure to be shock-absorbed through the cooperation of screws around and the fourth through holes 101. In this embodiment, the structure to be shock-absorbed is the self-absorbing vibration mechanical jitter laser gyro inertial measurement unit.

[0062] Refer to Figure 3 And Figure 7, the sealing cover 2 is a circular cover structure made of metal. The sealing cover 2 is used to cooperate with the cavity seat 1 and enclose a closed resonant cavity 6 with the cavity seat 1. The resonant ring 3, the adjustment ring 4 and the damping oil 5 are all arranged in the resonant cavity 6.

[0063] Specifically, referring to Figure 4 With Figure 7 , a plurality of third threaded holes 102 are also provided at intervals along the circumference at a position near the edge of the cavity seat 1. A plurality of feet 201 corresponding to the third threaded holes 102 one by one are provided at intervals along the circumference of the side of the sealing cover 2. A set of third through holes 202 coaxial with the corresponding third threaded holes 102 are provided on each foot 201. The cavity seat 1 and the sealing cover 2 are detachably connected through the cooperation of the third threaded holes 102, the third through holes 202 and the screws. In this embodiment, the number of the third threaded holes 102 on the cavity seat 1 is eight. Two of the third threaded holes 102 are in a group and are respectively located at the four corners of the cavity seat 1, and the two third threaded holes 102 in the same group are symmetrically located between the fourth through holes 101 to ensure the overall symmetry of the sealing cover 2.

[0064] Preferably, referring to Figure 3 , a sealing rubber ring 7 is provided on the mating surface of the cavity seat 1 and the sealing cover 2. Specifically, an annular sealing groove is provided at the bottom of the sealing cover 2, and the sealing rubber ring 7 is arranged in the sealing groove to ensure the sealing of the resonant cavity 6 and prevent the damping oil 5 in the resonant cavity 6 from leaking.

[0065] Referring to Figure 3 , the resonant mechanism is arranged in the resonant cavity 6, and one end of the resonant mechanism is detachably connected to the cavity seat 1, and there is a gap between the other end and the sealing cover 2 to generate a dynamic vibration absorption effect through the angular vibration resonance of the resonant mechanism. The damping oil 5 is filled between the resonant mechanism and the cavity wall of the resonant cavity 6 to generate an angular vibration damping effect through the damping oil 5.

[0066] Referring to Figure 5 , the resonant ring 3 is made of a damping alloy and has a symmetric flat structure to generate angular vibration resonance in the direction of its central axis. One end of the resonant ring 3 is detachably connected to the cavity seat 1, and there is a gap between the other end and the sealing cover 2 to generate a dynamic vibration absorption effect through the angular vibration resonance of the resonant ring 3. A plurality of symmetric spokes 301 are arranged in the middle of the resonant ring 3 to ensure that its first-order resonance point is the angular vibration in its normal direction, and the higher-order resonance frequency is much greater than the first-order resonance frequency.

[0067] Specifically, referring to Figure 4 With Figure 5, the resonance ring 3 includes a central block 302 and an annular body 303 with a rotary body structure. The central block 302 is located at the center of the inner ring of the annular body 303, and the side wall of the central block 302 is connected to the inner ring wall of the annular body 303 by four of the above-mentioned spokes 301. The four spokes 301 are distributed in a cross-shaped structure within the ring of the annular body 303. There are four first connection blocks 103 distributed in a cross-shaped structure on the cavity seat 1, and each first connection block 103 is provided with a first threaded hole 104. There are four second connection blocks 304 between the side wall of the central block 302 and the inner ring wall of the annular body 303, that is, there is a second connection block 304 between every two spokes 301. Each second connection block 304 is provided with a first through hole 305. The first connection blocks 103 and the second connection blocks 304 are in one-to-one correspondence, and the first threaded hole 104 and the corresponding first through hole 305 are coaxial. The cavity seat 1 and the resonance ring 3 are detachably connected through the cooperation of the first threaded hole 104, the first through hole 305, and a screw. In the specific application process, the resonance angular vibration frequency of the resonance ring 3 can be changed by designing spokes 301 with different thicknesses, so that its first-order resonance frequency can have multiple different types, corresponding to the vibration frequencies in three directions on the mechanical mechanism body that needs vibration absorption.

[0068] More specifically, referring to Figure 5 and Figure 6 , the side part of the annular body 303 is a stepped structure that is narrower at the top and wider at the bottom, and the wider end of the annular body 303 is connected to the cavity seat 1. Four second threaded holes 306 are equidistantly arranged along the circumferential direction on the bottom wall of the stepped structure. There are four second through holes 401 on the adjustment ring 4 that correspond to the second threaded holes 306 one by one. The adjustment ring 4 is sleeved on the narrow end of the annular body 303, and the adjustment ring 4 and the resonance ring 3 are detachably connected through the cooperation of the second threaded hole 306, the second through hole 401, and a screw. The resonance frequency of the damping resonator can be reduced by increasing the weight of the adjustment ring 4. In the specific application process, considering the processing error of the resonance ring 3 and the processing consistency of the actual laser gyro jitter frequency and other issues, the final resonance frequency of the damping shock absorber still needs to be finely adjusted by replacing adjustment rings 4 with different weights to make the actual resonance frequency exactly the same as the angular vibration frequencies in three directions on the structure body that needs vibration reduction.

[0069] Referring to Figure 3 , in this embodiment, the damping oil 5 is used to fill the cavity of the resonance cavity 6 between the resonance ring 3 and the adjustment ring 4, thereby increasing the vibration damping of the damping resonator and absorbing vibration energy.

[0070] In this embodiment, in order to ensure the performance of the damping shock absorber after it is installed on the mechanical structure body, the flatness requirement of the installation contact surface on the cavity seat 1 of the damping shock absorber is not less than 5 microns.

[0071] In this embodiment, the working principle of the damping shock absorber is based on the dynamic vibration absorption principle used in construction machinery. After the damping shock absorber is installed on the inertial measurement unit of the mechanically dithered laser gyroscope, if the forced angular vibration frequency and direction of the installation body caused by the laser gyroscope are the same as the resonant angular velocity frequency and direction of the damping shock absorber, through reasonable design, the torque applied to the installation body by the laser gyroscope dithering is exactly opposite to the torque applied to the installation body after the resonance of the damping shock absorber, then the vibration of the inertial measurement unit will be greatly reduced. At the same time, in order to avoid the problems of narrow vibration absorption bandwidth and resonance peak caused by undamped dynamic vibration absorption, in the structure of the damping shock absorber, the measure of filling damping oil 5 is adopted, and the resonance ring 3 is also processed from damping alloy, so that the whole damping shock absorber has good stability and meets the requirement of absorbing the angular vibration of the installation body of the inertial measurement unit of the laser gyroscope.

[0072] Embodiment 2

[0073] This embodiment discloses a self-vibration-absorbing mechanically dithered laser gyroscope inertial measurement unit, which includes an installation body 8, an accelerometer assembly 9, rubber shock absorbers 10, three laser gyroscopes 11, 12, 13, and three damping shock absorbers 14, 15, 16 in Embodiment 1. Among them, the accelerometer assembly 9 is fixedly connected to the installation body 8, the rubber shock absorbers 10 are arranged at symmetric positions around the installation body 8, the three laser gyroscopes 11, 12, 13 are respectively arranged on three orthogonal side surfaces of the installation body 8, and the three damping shock absorbers 14, 15, 16 are respectively arranged on the other three orthogonal side surfaces of the installation body 8. The frequencies and directions of the resonant angular velocities of the three damping shock absorbers 14, 15, 16 are the same as the frequencies and directions of the dithering angular velocities of the laser gyroscopes 11, 12, 13 installed on the side surfaces of the opposite installation body 8, so that it can absorb the angular vibration of the inertial measurement unit body caused by the opposite mechanically dithered laser gyroscopes 11, 12, 13.

[0074] Figure 8 is a structural schematic diagram of a traditional mechanically dithered laser gyroscope inertial measurement unit (IMU). The three mechanically dithered laser gyroscopes 11, 12, 13 are respectively fixed on the corresponding gyro installation bosses of the installation body 8 by screws, and the three laser gyroscopes are orthogonally arranged on three side surfaces of the installation body 8. One bottom surface of the rubber shock absorber 10 is fixed to the installation body 8 by screws, and the other side of the rubber shock absorber 10 is fixed to the external inertial navigation system structure by screws. Figure 8 A total of 8 rubber shock absorbers 10 are configured in it, so as to elastically support the entire inertial measurement unit. The accelerometer assembly 9 is fixed on the installation body 8. Each set of inertial measurement units generally includes three accelerometers for measuring the accelerometer information of the installation body 8.

[0075] Under normal working conditions, the mechanical dither laser gyroscope is in a high-frequency dither state. The dither angular velocity frequency is generally a fixed frequency between 300 Hz and 1500 Hz depending on the gyro type, and the dither amplitude is generally at the angular component level. The high-frequency dither of the laser gyroscope will generate a reaction torque on the mounting body 8, resulting in high-frequency angular vibration of the mounting body 8. Considering the relationship between the dither angular velocity in one direction and the vibration angular velocity of the mounting body 8, under the drive of the dither mechanism of the laser gyroscope, the laser gyroscope has a dither angular velocity ω G , then according to the characteristics of rigid body angular motion, the vibration angular velocity ω B of the mounting body 8 in this direction satisfies the following relationship:

[0076]

[0077] where, I G is the moment of inertia of the gyro sensitive axis, I B is the moment of rotation of the mounting body 8 assembly about the central axis, θ B = ∫ω B dt is the dither angle of the mounting body 8, K R is the elastic coefficient of the rubber shock absorber 10 in the IMU, and B R is the damping coefficient of the rubber shock absorber 10 in the IMU.

[0078] Since the resonance frequency of the rubber shock absorber 10 is much lower than the dither frequency of the laser gyroscope, when estimating the vibration amplitude of the mounting body 8, the effect of the rubber shock absorber 10 can usually be ignored, that is, the effects of K R , B R in the above formula are ignored, and thus the vibration angular velocity of the mounting body 8 can be estimated to be approximately:

[0079] ω B = (I G / I B )ω G

[0080] That is, the vibration angular velocity of the installation body 8 is determined by the ratio of the laser gyroscope to the moment of inertia of the installation body 8, and the angular vibration frequency of the installation body 8 is consistent with the dither frequency of the laser gyroscope. For example, if the dither amplitude of the laser gyroscope is 4 arc minutes (240 arc seconds) and the ratio of the moment of inertia of the laser gyroscope to the installation body 8 is 20, then the angular vibration amplitude of the installation body 8 is approximately 12 arc seconds. Here, only the angular vibration influence of the installation body 8 caused by the dither of one laser gyroscope is considered. For an actual inertial measurement unit, the above three laser gyroscopes 11, 12, and 13 will cause angular vibrations of the installation body 8 in three directions. If the sensitive axes of the laser gyroscopes 11, 12, and 13 do not pass through the centroid of the installation body 8, this will cause the installation body 8 to not only have three angular vibrations but also three linear vibrations. These vibrations will also be coupled and affect each other, not only causing vibration and noise problems in the system but also causing different changes in the vibration of the installation body 8 under the force state, and ultimately making the accuracy of the inertial navigation system vulnerable to the influence of the external structure and dynamic environment. Therefore, it is very necessary to take measures to reduce the vibration of the installation body 8 of the inertial measurement unit.

[0081] In this embodiment, the working principle of the damping shock absorber is based on the dynamic vibration absorption principle used in construction machinery. After the damping shock absorber is installed on the mechanically dithered laser gyro inertial measurement unit, if the forced angular vibration frequency and direction of the installation body 8 caused by the laser gyroscopes 11, 12, and 13 are consistent with the resonant angular velocity frequency and direction of the damping shock absorber, through reasonable design, the torque applied to the installation body 8 by the dither of the laser gyroscopes 11, 12, and 13 is exactly opposite to the torque applied to the installation body 8 after the resonance of the damping shock absorber, then the vibration of the inertial measurement unit will be greatly reduced. At the same time, in order to avoid the problems of narrow vibration absorption bandwidth and resonance peak caused by undamped dynamic vibration absorption, in the structure of the damping shock absorber, the measure of filling damping oil is adopted, and the resonance ring is also processed from damping alloy, so that the entire damping shock absorber has good stability and meets the requirement of absorbing the angular vibration of the installation body 8 of the laser gyro inertial measurement unit.

[0082] Figure 9 It is a schematic diagram of the self-vibration-absorbing mechanically dithered laser gyro inertial measurement unit provided in this embodiment. On six sides of the installation body 8, three orthogonal sides reserve laser gyro installation spaces and installation bosses for installing three mechanically dithered laser gyroscopes 11, 12, and 13, and the remaining three orthogonal sides reserve installation spaces and installation bosses for installing three damping shock absorbers 14, 15, and 16. The accelerometer assembly 9 is fixed to the installation body 8 with screws for measuring the motion acceleration of the installation body 8. Figure 9Rubber shock absorbers 10 are installed near the symmetric positions around the installation body 8. A total of 8 rubber shock absorbers 10 are configured. The inertial measurement unit is connected to the external inertial navigation system structure through the rubber shock absorbers 10. Among them, the resonant angular velocity frequency of the damping shock absorber 14 is the same as the jitter angular velocity frequency of the laser gyro 11, and the angular velocity directions of the two are on a straight line passing through the centroid of the inertial measurement unit; the resonant angular velocity frequency of the damping shock absorber 15 is the same as the jitter angular velocity frequency of the laser gyro 12, and the angular velocity directions of the two are on a straight line passing through the centroid of the inertial measurement unit; the resonant angular velocity frequency of the damping shock absorber 16 is the same as the jitter angular velocity frequency of the laser gyro 13, and the angular velocity directions of the two are on a straight line passing through the centroid of the inertial measurement unit. In order to ensure that the resonant frequencies of the damping shock absorbers 14, 15, and 16 do not change after installation, the flatness requirement of each set of boss mounting surfaces on the installation body 8 for installing the damping shock absorbers 14, 15, and 16 is not less than 5 microns.

[0083] When specifically applying the damping shock absorber and the self-absorbing vibration mechanical jitter laser gyro inertial measurement unit, the operation process is as follows:

[0084] (1) After installing the three laser gyros 11, 12, and 13 on the three orthogonal side surfaces of the self-absorbing vibration mechanical jitter laser gyro inertial measurement unit installation body 8, by testing the output state data of the three laser gyros 11, 12, and 13 used, obtain their accurate jitter frequencies, denoted as A-type, B-type, and C-type frequency values;

[0085] (2) After selecting three damping shock absorbers 14, 15, and 16 that are close to the A-type, B-type, and C-type frequencies, adjust the resonant frequencies of the damping shock absorbers 14, 15, and 16 by replacing adjustment rings of different weights, so that the central values of the resonant frequencies of the three damping shock absorbers 14, 15, and 16 are the A-type, B-type, and C-type frequencies respectively;

[0086] (3) Install and fix the three damping shock absorbers 14, 15, and 16 on the remaining side surfaces of the self-absorbing vibration mechanical jitter laser gyro inertial measurement unit installation body 8. When selecting the installation orientation, it is necessary to ensure that the resonant frequencies of the installed damping shock absorbers 14, 15, and 16 are the same as the jitter frequencies of the laser gyros 11, 12, and 13 on the opposite side surfaces.

[0087] According to Figure 9 the structural configuration of the self-absorbing vibration mechanical jitter laser gyro inertial measurement unit, each damping shock absorber can absorb the angular vibration of the installation body 8 caused by the jitter of the opposite mechanical jitter laser gyro. The three damping shock absorbers 14, 15, and 16 are used in combination, and just can absorb all the angular vibrations of the installation body 8 caused by the jitter of the laser gyros 11, 12, and 13, thus achieving a structural self-absorbing vibration effect and achieving the purpose of reducing vibration and noise of the inertial measurement unit. For Figure 9For the self-priming vibration mechanical dithering laser gyro inertial measurement unit, the analysis method of forced vibration caused by linear vibration can be referred to analyze the amplitude of angular vibration of the inertial measurement unit. Without considering the vibration coupling in multiple directions, the dynamic equation of the two-degree-of-freedom angular vibration damping system is established, and the angular vibration amplitude of the inertial measurement unit mounting body 8 in a single direction can be expressed as:

[0088]

[0089] where μ = I s / I B , f = ω0 / Ω0, g = ω G / Ω0, C c = 2I S Ω0, A B is the angular vibration amplitude of the inertial measurement unit, A0 = (I G / I B )A G is the vibration amplitude of the mounting body 8 without installing the damping shock absorber, A G is the dithering amplitude of the laser gyro, ω G is the dithering frequency of the laser gyro, I G is the rotational inertia of the dithering part of the laser gyro, I B is the rotational inertia of the inertial measurement unit, I S is the rotational inertia of the resonant part of the damping shock absorber, C is the damping coefficient of the damping shock absorber, k is the angular motion spring stiffness of the damping shock absorber, and K is the angular motion spring stiffness of the inertial measurement unit.

[0090] Through the analysis of the angular vibration amplitude A B of the inertial measurement unit, it can be seen that the vibration amplitude of the inertial measurement unit is closely related to the damping coefficient C of the damping shock absorber. Therefore, when designing the damping shock absorber, one task is to find the damping coefficient value that minimizes A B . The reasonable structure of the damping shock absorber can be designed according to the damping coefficient, and the appropriate damping alloy and damping oil can be found to meet the design requirements of the damping shock absorber. Or the structure of the damping shock absorber can be designed according to the specific damping alloy and damping oil to make it have the required angular vibration attenuation of the inertial measurement unit mounting body 8.

[0091] For the 90-type mechanical dithering laser gyro inertial measurement unit, an example of the vibration attenuation after installing the damping shock absorber can be given. For example, according to the common structure of the inertial measurement unit, the above parameters can be roughly taken as follows: ω0 = ω G = 400Hz, Ω0 = 40Hz, f = g = 10, μ = 0.01, then the maximum value of the vibration amplitude of the mounting body 8 can be obtained as:

[0092] (AB ) Max = A0 / 100

[0093] That is, in an ideal situation, the angular vibration amplitude of the mounting body 8 can be reduced to 1 / 100 of the original through the damping shock absorber, thereby greatly reducing the vibration noise of the inertial measurement unit. Of course, in an actual mechanical jitter laser gyro inertial measurement unit, the jitter direction of the laser gyro, the centroid of the inertial measurement unit, the resonance direction of the damping shock absorber, etc. are very likely to deviate, which will not only cause the linear vibration of the mounting body 8, but also lead to a decrease in the damping efficiency. Considering various error factors comprehensively, even if the ideal situation cannot be achieved, by reasonably designing the structure of the damping shock absorber and the inertial measurement unit, reducing the vibration amplitude of the mounting body 8 to 1 / 10 of the original can also achieve a significant damping and noise reduction effect. Of course, in order to achieve a good damping effect, theoretically, the optimal damping scheme requires that the resonance angular velocity vector of the damping shock absorber and the jitter angular velocity vector of the corresponding laser gyro are on a straight line, and this straight line passes through the centroid of the inertial measurement unit.

[0094] Through the above scheme, the vibration noise of the mounting body 8 of the mechanical jitter laser gyro inertial measurement unit can be effectively reduced. Compared with the existing scheme, the present embodiment does not change the structure of the jitter wheel of the laser gyro and has no impact on the performance of the laser gyro. And the damping shock absorber in the present embodiment is installed on the remaining three sides of the six sides of the mounting body 8 of the inertial measurement unit where no laser gyro is installed. Through reasonable design, it will not cause an increase in the size and weight of the self-absorbing vibration mechanical jitter laser gyro inertial measurement unit, nor will it change the damping structure of the inertial measurement unit, and has no impact on the attitude accuracy of the inertial navigation system. Therefore, while reducing the vibration and noise of the inertial navigation system, the present invention will not bring additional adverse effects, and finally will improve the performance of the laser gyro inertial navigation system and broaden the application scenarios of the laser gyro inertial navigation system.

[0095] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. All equivalent structural transformations made under the inventive concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A damping shock absorber, characterized in that, It includes a cavity seat, a resonant mechanism and a sealing cover; The sealing cover is detachably connected to the cavity seat, and a closed resonant cavity is formed between the cavity seat and the sealing cover; The resonant mechanism is arranged in the resonant cavity, and one end of the resonant mechanism is detachably connected to the cavity seat, and there is a gap between the other end and the sealing cover to generate a dynamic vibration absorption effect through the angular vibration resonance of the resonant mechanism; Damping oil is filled between the resonant mechanism and the cavity wall of the resonant cavity to generate an angular vibration damping effect through the damping oil; The resonant mechanism includes a resonant ring, one end of the resonant ring is detachably connected to the cavity seat, and there is a gap between the other end and the sealing cover to generate a dynamic vibration absorption effect through the angular vibration resonance of the resonant ring; The resonant ring includes a central block and an annular body with a rotary body structure. The central block is located at the inner ring center of the annular body, and the side wall of the central block is connected to the inner ring wall of the annular body through a plurality of spokes evenly distributed at equal intervals in the circumferential direction.

2. The damping shock absorber according to claim 1, characterized in that, The resonant mechanism further includes an adjustment ring; The adjustment ring is detachably sleeved on the resonant ring to adjust the resonant frequency of the resonant ring to be consistent with the angular frequency to be absorbed.

3. The damping shock absorber according to claim 2, characterized in that, At least one first connection block is provided on the cavity seat, and a first threaded hole is provided on the first connection block; At least one second connection block is provided between the side wall of the central block and the inner ring wall of the annular body, and a first through hole is provided on the second connection block; The first connection blocks and the second connection blocks are in one-to-one correspondence, and the first threaded hole and the corresponding first through hole are coaxial.

4. The damping shock absorber according to claim 3, characterized in that, The side part of the annular body is a stepped structure with a narrow upper part and a wide lower part, and the wider end of the annular body is connected to the cavity seat; A plurality of second threaded holes are provided at intervals in the circumferential direction on the bottom wall of the stepped structure, and a plurality of second through holes corresponding to the second threaded holes one by one are provided on the adjustment ring.

5. The damping shock absorber according to claim 4, characterized in that, A convex structure is provided at a position around the second threaded hole on the bottom wall of the stepped structure so that there is a gap between the adjustment ring and the bottom wall of the stepped structure.

6. The damping shock absorber according to claim 1 or 2, characterized in that, A plurality of third threaded holes are provided at intervals in the circumferential direction at a position near the edge of the cavity seat, and a plurality of third through holes corresponding to the third threaded holes one by one are provided on the sealing cover; A sealing rubber ring is provided on the mating surface of the cavity seat and the sealing cover.

7. The damping shock absorber according to claim 1 or 2, characterized in that A plurality of fourth through holes are provided at intervals in the circumferential direction at a position near the edge of the cavity seat for mounting the cavity seat on an inertial measurement unit.

8. A self-absorbing vibration mechanical jitter laser gyro inertial measurement unit, including a mounting body, an accelerometer assembly, a rubber shock absorber and three laser gyros; The accelerometer assembly is fixedly connected to the mounting body, the rubber shock absorber is arranged at symmetric positions around the mounting body, and the three laser gyros are respectively arranged on three orthogonal side surfaces of the mounting body; It is characterized in that It further includes three damping shock absorbers according to any one of claims 1 to 7, and the three damping shock absorbers are respectively arranged on the other three orthogonal side surfaces of the mounting body.

9. The self-suction vibration mechanical dithering laser gyro inertial measurement unit according to claim 8, characterized in that, The frequencies and directions of the resonant angular velocities of the three damping shock absorbers are the same as those of the angular velocities of the laser gyroscope jitter mounted on the side of the opposite mounting body.

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