Three-axis north-seeking gyroscope and north-seeking method thereof

Abstract

The invention provides a three-axis north-seeking gyroscope and a north-seeking method thereof.The three-axis north-seeking gyroscope comprises an installation reference part, a connector, a first circuit board, a second circuit board, a third circuit board, a fourth circuit board, a fifth circuit board and a fixing cover, and an integrated installation frame is arranged on the installation reference surface of the installation reference part; the first circuit board is arranged on a first circuit board mounting step on the inner side of the bottom of the mounting frame; the second circuit board is arranged on a second circuit board installation step on the inner side of the upper portion of the installation frame, and the arrangement direction of the second circuit board installation step is perpendicular to the arrangement direction of the first circuit board installation step. And the fourth circuit board and the fifth circuit board are respectively arranged on a fourth circuit board mounting plane and a fifth circuit board mounting plane on two adjacent side surfaces of the mounting frame. According to the invention, not only can the miniaturization design of the product be realized, but also the requirements of rapid assembly of the product and stable and reliable structure after assembly can be met.

Description

Technical Field

[0001] The present invention relates to a gyroscope, in particular to a miniaturized three-axis north-seeking gyroscope, and further to a north-seeking method of the three-axis north-seeking gyroscope. Background Art

[0002] The north-seeking gyroscope is a fast orientation device used to measure the north azimuth. It has the characteristics of high precision, long life and simple structure, and has been widely used in the measurement and application of initial orientation. The three-axis north-seeking gyroscope is mainly composed of a three-axis high-precision MEMS gyroscope and a three-axis MEMS accelerometer. MEMS refers to Micro-Electro-Mechanical System, which requires more integrated electronic components. Therefore, with the expansion of application fields and the upgrading of products, new challenges have been raised for the volume and size of the three-axis north-seeking gyroscope. It is not only necessary to meet the miniaturization design of the product, but also to meet the requirements of rapid assembly of the product and stable and reliable structure after assembly on the basis of miniaturization design. The existing three-axis north-seeking gyroscope obviously cannot meet the above requirements. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a three-axis north-seeking gyroscope with a miniaturized design, which can not only realize the miniaturized design of the product, but also meet the requirements of rapid assembly of the product and stable and reliable structure after assembly.

[0004] To this end, the present invention provides a three-axis north-seeking gyroscope, comprising: a mounting reference member, a connector, a first circuit board, a second circuit board, a third circuit board, a fourth circuit board, a fifth circuit board and a fixed cover, the bottom of the mounting reference member is a mounting reference surface, an integrated mounting frame is arranged on the mounting reference surface, the mounting frame is arranged between the mounting reference member and the fixed cover, a first circuit board mounting step is arranged on the inner side of the bottom of the mounting frame, and the first circuit board is arranged on the first circuit board mounting step; a second circuit board mounting step is arranged on the inner side of the upper part of the mounting frame, the setting direction of the second circuit board mounting step is perpendicular to the setting direction of the first circuit board mounting step, and the second circuit board is arranged on the second circuit board mounting step; the third circuit board is arranged on the top of the mounting frame; a fourth circuit board mounting plane and a fifth circuit board mounting plane are arranged on two adjacent sides of the mounting frame, the fourth circuit board and the fifth circuit board are respectively arranged on the fourth circuit board mounting plane and the fifth circuit board mounting plane, and are respectively perpendicular to the first circuit board; the connector is arranged on the outer side of the mounting reference member, and is staggered with the fourth circuit board mounting plane and the fifth circuit board mounting plane.

[0005] A further improvement of the present invention is that a fixing cover mounting step is also provided on the mounting reference member, the fixing cover mounting step is provided on the inner side of the bottom of the fixing cover, and the shape and size of the fixing cover mounting step are respectively matched with the shape and size of the fixing cover; the mounting frame is provided on the fixing cover mounting step.

[0006] A further improvement of the present invention is that an elastic outer edge is provided on the side of the fixing cover mounting step, and the elastic outer edge is interference connected with the inner side of the bottom of the fixing cover; a first mounting hole is provided on the mounting reference surface, and the first mounting hole is provided on the outer side of the fixing cover mounting step, and the mounting reference surface is connected to the fixing cover through the first mounting hole.

[0007] A further improvement of the present invention is that a connector mounting portion is provided on the side of the mounting reference member, a blocking piece is provided on the inner side of the connector mounting portion, and an installation window is provided on the fixing cover, the position and size of the installation window match the position and size of the connector mounting portion, and the blocking piece is embedded in the inner side of the installation window.

[0008] A further improvement of the present invention is that the fourth circuit board mounting plane and the fifth circuit board mounting plane are both concave-shaped mounting planes, and circuit board mounting holes are provided on the ears on both sides of the mounting planes.

[0009] A further improvement of the present invention is that a cable connection portion is provided on one side of the second circuit board and one side of the third circuit board, and the position of the cable connection portion is staggered with the position of the connector, the fourth circuit board mounting plane and the fifth circuit board mounting plane.

[0010] The present invention also provides a north-seeking method of a three-axis north-seeking gyroscope, which uses the three-axis north-seeking gyroscope as described above and includes the following steps:

[0011] Step S1, define the carrier coordinate system b0 and the navigation coordinate system n0 at the initial moment, and obtain the attitude matrix at the initial moment according to the orientation relationship between the carrier coordinate system b0 and the navigation coordinate system n0 Complete the first alignment;

[0012] Step S2, establishing a Kalman filter model, performing zero-speed observation Kalman filter correction through the Kalman filter model, and achieving re-alignment to obtain a north-seeking result.

[0013] A further improvement of the present invention is that in the step S1, after initialization, the gravity vector of a preset fixed point on the surface of the earth is observed from the navigation coordinate system n, the direction of the gravity vector points to the center of the earth, the direction of the rate of change of the gravity vector is the direction of the earth's rotation, the direction and the rate of change of the gravity vector are used as the horizontal and azimuth information of the preset fixed point, and the attitude matrix at the initial moment is obtained according to the dual-vector attitude determination algorithm

[0014] A further improvement of the present invention is that the first alignment time of step S1 is extended according to a preset time threshold.

[0015] A further improvement of the present invention is that in step S2, by formula Establish a Kalman filter model, where is the east misalignment angle, is the north misalignment angle, is the celestial misalignment angle, δv e is the eastward velocity error, δv n is the north velocity error, δv u is the celestial velocity error, and is the random constant drift of the three-axis gyroscope, and is the equivalent accelerometer random constant drift; represents the differential of X; F represents the state transfer matrix, represents the cross product of the Earth's rotation vector; g n × represents the cross product of the gravitational acceleration vector; 0 3×3 Represents a 3 by 3 zero matrix; 0 6×12 Represents a 6 by 12 zero matrix; I 3×3 represents the 3×3 identity matrix; W represents the system state noise; V represents the system measurement noise.

[0016] Compared with the prior art, the beneficial effects of the present invention are: an integrated mounting frame is provided on the mounting reference surface, a first circuit board mounting step is provided on the inner side of the bottom of the mounting frame, and the first circuit board is provided on the first circuit board mounting step; a fourth circuit board mounting plane and a fifth circuit board mounting plane are provided on two adjacent side surfaces of the mounting frame, the fourth circuit board and the fifth circuit board are respectively provided on the fourth circuit board mounting plane and the fifth circuit board mounting plane, and are respectively perpendicular to the first circuit board, so that a high-precision MEMS gyroscope can be respectively installed through the first circuit board, the fourth circuit board and the fifth circuit board, so that a total of three high-precision MEMS gyroscopes can be arranged in a limited space, and the physical structure is used to ensure that the circuit boards where the three high-precision MEMS gyroscopes are located are perpendicular to each other, thereby ensuring the three-axis measurement stability and reliability of the gyroscope.

[0017] On this basis, a second circuit board mounting step is arranged on the inner side of the upper part of the mounting frame, and the setting direction of the second circuit board mounting step is perpendicular to the setting direction of the first circuit board mounting step. The second circuit board is arranged on the second circuit board mounting step. On the one hand, the second circuit board mounting step can be used to realize the setting of the second circuit board as a main circuit board. The second circuit board is preferably a six-axis IMU measurement circuit, which integrates a high-performance processor of a DOUBLE-type double-precision DFPU for realizing inertial measurement. And through the spacing and direction between the first circuit board mounting step and the second circuit board mounting step, it is well ensured that there is no interference and collision between the first circuit board and the second circuit board, and the measurement accuracy of the product is affected due to different use environments or high-speed movement; on the other hand, since the setting direction of the second circuit board mounting step is perpendicular to the setting direction of the first circuit board mounting step, then, when assembling the first circuit board, the second circuit board step will not have a blocking problem, and there is no need to perform a avoidance design, so that the shape of each circuit board is more regular, which is convenient for batch processing and manufacturing, and it is also convenient to meet the requirements of rapid assembly of products and stable and reliable structure after assembly. The third circuit board is arranged on the top of the mounting frame to provide an auxiliary inertial measurement circuit, thereby further improving the accuracy and reliability of inertial measurement. The connector of the present invention is arranged on the outside of the mounting reference component and is staggered with the fourth circuit board mounting plane and the fifth circuit board mounting plane, thereby being able to effectively utilize the side spaces of the mounting reference component and improving the space utilization of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the explosion structure of an embodiment of the present invention;

[0019] Figure 2It is a schematic diagram of the three-dimensional structure of an embodiment of the present invention;

[0020] Figure 3 It is a schematic diagram of the working process of an embodiment of the present invention.

[0021] Figure identification: 1-installation reference member; 2-connector installation part; 3-connector; 4-second product installation hole; 5-second circuit board installation step; 6-first circuit board; 7-first fixing screw; 8-second circuit board installation hole; 9-second fixing screw; 10-second circuit board; 11-third circuit board installation hole; 12-fixing cover screw; 13-fourth circuit board installation step; 14-fourth circuit board; 15-fourth fixing screw; 16-fourth circuit board installation hole; 17-first circuit board installation step; 18-first circuit board installation hole; 19-fifth circuit board installation hole; 20-third circuit board installation step; 21-fifth fixing screw; 22-fifth circuit board installation plane; 23-fifth circuit board; 24-third circuit board; 25-third fixing screw; 26-fixing cover; 27-installation frame; 28-fixing cover installation step; 29-first installation hole; 30-blocking piece; 31-installation window; 32-cable connection part; 33-installation recess. DETAILED DESCRIPTION

[0022] In the description of the present invention, if it involves a description of orientation, for example, the orientation or position relationship indicated by "upper", "lower", "front", "back", "left", "right", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. If a feature is referred to as being "set", "fixed", "connected", or "installed" on another feature, it can be directly set, fixed, or connected to the other feature, or it can be indirectly set, fixed, connected, or installed on the other feature.

[0023] In the description of the present invention, if "several" is involved, it means more than one; if "multiple" is involved, it means more than two; if "greater than", "less than", or "exceed" is involved, it should be understood as not including the number itself; if "above", "below", or "within" is involved, it should be understood as including the number itself. If "first", "second", or "third" is involved, it should be understood as being used only to distinguish the names of the same or similar technical features, and should not be understood as implying / indicating the relative importance of the technical features, the number of the technical features, or the order of the technical features.

[0024] The preferred embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0025] like Figure 1 and Figure 2 As shown, a three-axis north-seeking gyroscope is provided, including: a mounting reference member 1, a connector 3, a first circuit board 6, a second circuit board 10, a third circuit board 24, a fourth circuit board 14, a fifth circuit board 23 and a fixing cover 26, the bottom of the mounting reference member 1 is a mounting reference surface, an integrated mounting frame 27 is arranged on the mounting reference surface, the mounting frame 27 is arranged between the mounting reference member 1 and the fixing cover 26, a first circuit board mounting step 17 is arranged on the inner side of the bottom of the mounting frame 27, the first circuit board 6 is arranged on the first circuit board mounting step 17; a second circuit board mounting step 5 is arranged on the inner side of the upper part of the mounting frame 27, the second circuit board mounting step 5 The setting direction is perpendicular to the setting direction of the first circuit board mounting step 17, and the second circuit board 10 is arranged on the second circuit board mounting step 5; the third circuit board 24 is arranged on the top of the mounting frame 27; the two adjacent sides of the mounting frame 27 are provided with a fourth circuit board mounting plane 13 and a fifth circuit board mounting plane 22, and the fourth circuit board 14 and the fifth circuit board 23 are respectively arranged on the fourth circuit board mounting plane 13 and the fifth circuit board mounting plane 22, and are respectively perpendicular to the first circuit board 6; the connector 3 is arranged on the outer side of the mounting reference member 1, and is staggered with the fourth circuit board mounting plane 13 and the fifth circuit board mounting plane 22.

[0026] In this embodiment, an integrated mounting frame 27 is provided on the mounting reference surface of the mounting reference member 1. The mounting frame 27 is used to install and fix five different circuit boards by utilizing efficient space design. The first circuit board 6, the fourth circuit board 14 and the fifth circuit board 23 are used to integrate high-precision MEMS gyroscopes respectively, totaling three high-precision MEMS gyroscopes; the second circuit board 10 is used as the main circuit board to integrate the six-axis IMU measurement unit based on the accelerometer, that is, the six-axis inertial measurement unit; the third circuit board 24 is used as the second auxiliary inertial measurement circuit board to integrate the inertial measurement unit (IMU) based on the accelerometer. The overall product structure obviously realizes a miniaturized and lightweight design. The inertial measurement unit (IMU) is preferably initially aligned by a high-precision MEMS gyroscope, an accelerometer and latitude and outputs the heading angle information of the initial north search, that is, the first alignment process is realized; then the processor solves and outputs the attitude information and heading maintenance in real time according to the six-axis IMU information to realize the re-alignment process. Of course, this north search method is one of the preferred methods. The present north search method can also be directly adopted in this embodiment.

[0027] Among them, the first circuit board mounting step 17 is set on the inner side of the bottom of the mounting frame 27 described in this embodiment, and the first circuit board mounting step 17 is provided with a mounting hole. The first circuit board mounting holes 18 are set around the first circuit board 6. The first circuit board 6 is detachably set on the first circuit board mounting step 17 through the first screws 7 and the first circuit board mounting holes 18. A fourth circuit board mounting plane 13 and a fifth circuit board mounting plane 22 are provided on two adjacent sides of the mounting frame 27; a fourth circuit board mounting hole 16 is provided on the fourth circuit board 14, and the fourth circuit board 14 is arranged on the fourth circuit board mounting plane 13 through the fourth circuit board mounting hole 16 and the fourth fixing screw 15; a fifth circuit board mounting hole 19 is provided on the fifth circuit board 23, and the fifth circuit board 23 is arranged on the fifth circuit board mounting plane 22 through the fifth circuit board mounting hole 19 and the fifth fixing screw 21; and the fourth circuit board mounting plane 13 and the fifth circuit board mounting plane 22 are respectively perpendicular to the first circuit board 6, so that a high-precision MEMS gyroscope can be respectively installed through the first circuit board 6, the fourth circuit board 14 and the fifth circuit board 23, so that a total of three high-precision MEMS gyroscopes can be arranged in a limited space, and the physical structure is used to ensure that the circuit boards where the three high-precision MEMS gyroscopes are located are mutually perpendicular, thereby ensuring the three-axis measurement stability and reliability of the gyroscope.

[0028] Preferably, in this embodiment, the height of the first circuit board mounting step 17 is preferably between 1 / 6 and 1 / 5 of the height of the mounting frame 27, instead of directly locking the first circuit board 6 on the mounting reference plane. This not only ensures efficient use of the bottom inner space of the mounting frame 27 and reserves sufficient space for the upper and top parts, but also can raise the first circuit board 6 according to a preset ratio, so that the components on the first circuit board 6 always maintain a certain distance from the mounting reference plane, thereby avoiding damage to the high-precision MEMS gyroscope during high-speed movement and ensuring the reliable performance of the product.

[0029] On this basis, a second circuit board mounting step 5 is arranged on the inner side of the upper part of the mounting frame 27, and the setting direction of the second circuit board mounting step 5 is perpendicular to the setting direction of the first circuit board mounting step 17. Second circuit board mounting holes 8 are arranged around the second circuit board 10, and the second circuit board 10 is detachably arranged on the second circuit board mounting step 5 through the second circuit board mounting hole 8 and the second fixing screw 9. On the one hand, the second circuit board mounting step 5 can be used to realize the setting of the second circuit board 10 as a main circuit board. The second circuit board 10 is preferably a six-axis IMU measurement circuit, which integrates a DOUBLE-type double-precision DFPU high-performance processor for realizing inertial measurement, and utilizes the first circuit board mounting step 17 and the second circuit board The spacing and direction between the installation steps 5 ensure that there will be no interference or collision between the first circuit board 6 and the second circuit board 10, and the measurement accuracy of the product will not be affected due to different use environments or high-speed movement; on the other hand, since the setting direction of the second circuit board installation step 5 is perpendicular to the setting direction of the first circuit board installation step 17, when assembling the first circuit board 6, the second circuit board 10 step will not be blocked, and there is no need to perform avoidance design, so that the shapes of each circuit board are more regular, and the first circuit board 6 can be designed to be completely consistent with the fourth circuit board 14 and the fifth circuit board 23, thereby improving the consistency and universal design of the product, facilitating batch processing and manufacturing, and also facilitating meeting the requirements of rapid assembly of the product and stable and reliable structure after assembly.

[0030] Preferably, in this embodiment, the height of the second circuit board mounting step 5 is preferably between 2 / 3-3 / 4 of the height of the mounting frame 27, rather than directly locking the second circuit board 10 in the middle of the mounting frame 27, which not only reserves more space for the high-precision MEMS gyroscope at the bottom and sides and provides a wiring position for the connector 3, but also facilitates shortening the distance between the second circuit board 10 and the third circuit board 24 for quick connection. The connector 3 is preferably a metal rectangular connector, the fixing cover 26 is preferably an aviation aluminum cover, and the mounting reference part 1 is preferably provided with second mounting holes 4 around it for installation and fixation of the three-axis north-seeking gyroscope.

[0031] In this embodiment, a third circuit board mounting step 20 is provided on the top of the mounting frame 27, and third circuit board mounting holes 11 are provided around the third circuit board 24. The third circuit board 24 is detachably mounted on the third circuit board mounting step 20 on the top of the mounting frame 27 through the third circuit board mounting holes 11 and third fixing screws 25, so as to provide an auxiliary inertial measurement circuit and further improve the accuracy and reliability of inertial measurement. During actual assembly, the assembly sequence is the first circuit board 6, the second circuit board 10 and the third circuit board 24 from bottom to top. No avoidance or borrowing operation is required during assembly, and the assembly process is simple and efficient. The structure after assembly is also stable and reliable.

[0032] The connector 3 described in this embodiment is arranged on the outside of the mounting reference member 1 and is staggered with the fourth circuit board mounting plane 13 and the fifth circuit board mounting plane 22, thereby being able to effectively utilize the side spaces of the mounting reference member 1 and improve the space utilization of the product.

[0033] Preferably, Figure 1 As shown, the mounting reference member 1 of this embodiment is also provided with a fixed cover mounting step 28, which is arranged on the inner side of the bottom of the fixed cover 26, and the shape and size of the fixed cover mounting step 28 are respectively matched with the shape and size of the fixed cover 26; the mounting frame 27 is arranged on the fixed cover mounting step 28, that is, the entire integrated mounting frame 27 is raised and arranged on the mounting reference surface, and such a design can be more conducive to improving the waterproof performance of the product. For example, an elastic outer edge is arranged on the side of the fixed cover mounting step 28, and the elastic outer edge is interference-connected with the inner side of the bottom of the fixed cover 26; a first mounting hole 29 is arranged on the outer side of the fixed cover mounting step 28, and the mounting reference surface is connected to the fixed cover 26 through the first mounting hole 29 and the fixed cover screw 12, and then the fixed cover 26 is elastically interference-locked on the outer side of the fixed cover mounting step 28, so as to achieve a highly reliable waterproof design.

[0034] Preferably, Figure 1As shown, a connector mounting portion 2 is provided on the side of the mounting reference member 1 of the present embodiment, and a blocking piece 30 is provided on the inner side of the connector mounting portion 2, and the area of ​​the blocking piece 30 is larger than the area of ​​the connector mounting portion 2, and a mounting window 31 is provided on the fixing cover 26, and the position and size of the mounting window 31 match the position and size of the connector mounting portion 2. During assembly, the blocking piece 30 is embedded into the inner side of the mounting window 31, thereby ensuring the waterproof performance of the side where the connector 3 is located, and also providing reinforcement and support for the connector mounting portion 2, thereby avoiding affecting the service life of the product due to the insertion of the connector 3.

[0035] like Figure 1 As shown, the fourth circuit board mounting plane 13 and the fifth circuit board mounting plane 22 of the present embodiment are both concave-shaped mounting planes, and circuit board mounting holes are provided on the ears on both sides of the mounting planes, which are used to quickly and efficiently fix the fourth circuit board 14 and the fifth circuit board 23, and after fixation, a good three-axis structure that is perpendicular to each other can be maintained, providing a better hardware foundation for three-axis measurement.

[0036] like Figure 1 As shown, in this embodiment, a cable connection portion 32 is provided on one side of the second circuit board 10 and one side of the third circuit board 24, and the position of the cable connection portion 32 is staggered with the positions of the connector 3, the fourth circuit board mounting plane 13 and the fifth circuit board mounting plane 22, that is, the second circuit board 10 and the third circuit board 24 can be quickly plugged in through the cable structure on one side of the fourth plane outside the connector 3, the fourth circuit board mounting plane 13 and the fifth circuit board mounting plane 22, further improving the assembly efficiency of the product without any interference and without the need for avoidance or borrowing design.

[0037] like Figure 2 As shown, the bottom of the mounting reference member 1 described in this embodiment is preferably provided with a mounting recess 33, the width of the mounting recess 33 is smaller than the width of the fixing cover mounting step 28, and the thickness of the upward recess is controlled to be 1 to 3 mm. Such detailed design can not only ensure the structural reliability of the fixing cover mounting step 28, but also provide a certain deformation space for the overall installation of the three-axis north-seeking gyroscope. Even if it is installed on an imperfectly flat plane, it will not change the structure of the mounting frame 27 and the relationship between the various circuit boards inside it (the first circuit board 6, the second circuit board 10, the third circuit board 24, the fourth circuit board 14 and the fifth circuit board 23), that is, it will not destroy the perpendicular relationship with each other, so that the assembled product is more stable and reliable.

[0038] like Figure 3As shown, this embodiment also provides a north-seeking method of a three-axis north-seeking gyroscope, which uses the three-axis north-seeking gyroscope as described above and includes the following steps:

[0039] Step S1, define the carrier coordinate system b0 and the navigation coordinate system n0 at the initial moment, and obtain the attitude matrix at the initial moment according to the orientation relationship between the carrier coordinate system b0 and the navigation coordinate system n0 Complete the first alignment;

[0040] Step S2, establishing a Kalman filter model, performing zero-speed observation Kalman filter correction through the Kalman filter model, and achieving re-alignment to obtain a north-seeking result.

[0041] The first alignment of this embodiment can also be called rough alignment. The rough alignment process preferably uses indirect rough alignment, which defines the carrier coordinate system b0 (also called carrier inertial system) at the initial moment, which coincides with the carrier coordinate system b system at the moment of starting north search, and then does not rotate relative to the inertial space; the navigation coordinate system n0 (navigation inertial system, referred to as n0 system) at the initial moment coincides with the navigation coordinate system n system at the moment of starting north search, and then does not rotate relative to the inertial space. Therefore, the final solution is to solve the orientation relationship between the carrier coordinate system b0 and the navigation coordinate system n0, that is, the attitude matrix This allows for initial alignment.

[0042] This embodiment solves the orientation relationship between the carrier coordinate system b0 and the navigation coordinate system n0, that is, the attitude matrix The process is as follows: First, define the projection G of the gravity vector in the n0 system n0 for: Among them G n =[0 0-g]', is a constant vector, g is the constant value of gravitational acceleration, and is the attitude rotation matrix between the n system and the n0 system, Represents the attitude rotation matrix The differential of is the Earth's rotation angular velocity, The cross product of the Earth's rotation vector, a mathematical representation of the Earth's rotation vector, is a 3 by 3 matrix. It represents the cross product of the projection vector of the angular velocity of the n system relative to the n0 system on the n system. Since the motion of the n system relative to the n0 system can be regarded as a fixed-axis rotation, it can be equal to the rotation vector of the earth.

[0043] because The angular velocity of the Earth's rotation is a constant, that is, the n system rotates with respect to the n0 system. Solving the above differential equation, we can get: Where t is the time, Lat represents the local geographical latitude, and wie Represents the Earth's rotation angle rate constant, approximately 15.0411° / h.

[0044] Secondly, the specific force output of the accelerometer is projected in the b0 system as: in, and are the specific force values ​​in b system and b0 system respectively, Represents the real-time attitude matrix. The real-time attitude matrix is ​​expressed by the formula Perform differential calculation, that is In the formula is the measurement value of the gyroscope, the initial value of the attitude array (Unit matrix I), the real-time attitude matrix can be obtained by using the attitude update algorithm It represents the cross product of the projection vector of the angular velocity of system b relative to system b0 on system b. System b0 does not rotate relative to the inertial space, so the angular velocity of system b relative to the inertial system (system b0) can be regarded as the angular motion relative to system b0).

[0045] Finally, through the posture matrix Establish the relationship between gravitational acceleration and specific force measurements: In the formula, It represents the measured value (specific force value) of the accelerometer. The superscript ~ indicates that the measured value has an error. The superscript b indicates that the vector is in the b system. sf is the abbreviation of specific force. It represents the measurement specific force error of the accelerometer. In theory, as long as the gravity and its specific force measurement values ​​at two moments are obtained and two matrix equations are established, the attitude matrix can be solved using the dual-vector attitude determination algorithm. However, in order to reduce the influence of linear motion interference, remember during the initial alignment: Usually t2=2t1, t1 is the initial alignment time, and t2 is the alignment end time. It means that one of the two vectors is constructed by integrating the right side of the equation, and the superscript b0 system means that the vector is in the b0 system; Represents the i-th projection of the gravity vector in the n0 system, used to represent the other one of the double vectors, where i is a natural number.

[0046] In step S1 of this embodiment, after initialization, the gravity vector of a preset fixed point on the surface of the earth (a preset fixed point can be set and adjusted according to actual conditions and needs) is observed from the navigation coordinate system n. The direction of the gravity vector gradually changes with the rotation of the earth, showing a periodic change, and forms a cone after one circle. The direction of the gravity vector points to the center of the earth, and the direction of the rate of change of the gravity vector is the direction of the earth's rotation. Therefore, the direction and rate of change of the gravity vector contain local geographic information, and the direction and rate of change of the gravity vector can be used as the horizontal and azimuth information of the preset fixed point. The attitude matrix at the initial moment is obtained according to the dual-vector attitude determination algorithm. Ignoring the accelerometer measurement error and linear acceleration interference can better resist angular shake interference.

[0047] More specifically, this embodiment uses a dual-vector attitude determination algorithm Perform calculations, It is equivalent to roughly aligning the attitude matrix at the initial moment, that is, Obviously, in order to obtain the attitude matrix at the end of the rough alignment, the formula The posture matrix can be calculated The pose matrix at the end of the coarse alignment phase is Provides initial attitude matrix for fine alignment, Represents the attitude rotation matrix from n0 system to n system; where, and It is an inverse relationship.

[0048] This embodiment extends the first alignment time of step S1 according to the preset time threshold, which can make the indirect alignment more practical and effective. The preset time threshold is the preset alignment time of the coarse alignment. The preset time threshold of the coarse alignment time is selected by default to be in the order of minutes or more, such as about 1 to 3 minutes, to ensure the balance between the coarse alignment accuracy and the coarse alignment time as much as possible. Of course, the preset time threshold can be set and adjusted according to the actual situation, and can be selected and adjusted according to the accuracy of the IMU device.

[0049] The re-alignment described in this embodiment refers to fine alignment, which is performed on the basis of the completion of rough alignment to obtain more accurate north-seeking accuracy. North-seeking is performed under a static base. Since the geographical location of the north-seeker system does not move significantly and the real speed is zero, at most there is a small linear shake caused by interference. Therefore, this embodiment can use zero-speed observation to establish a Kalman filter model.

[0050] Specifically, in step S2 of this embodiment, by formula Establish a Kalman filter model, where is the east misalignment angle, is the north misalignment angle, is the celestial misalignment angle, δv e is the eastward velocity error, δv n is the north velocity error, δv u is the celestial velocity error, and is the random constant drift of the three-axis gyroscope, and is the equivalent accelerometer random constant drift; represents the differential of X; F represents the state transfer matrix, represents the cross product of the Earth's rotation vector; g n × represents the cross product of the gravitational acceleration vector; 0 3×3 Represents a 3 by 3 zero matrix; 0 6×12 Represents a 6 by 12 zero matrix; I 3×3 represents the 3×3 identity matrix; W represents the system state noise; V represents the system measurement noise.

[0051] Simply put, step S2 of this embodiment is to perform zero-speed observation Kalman filter correction on the IMU, estimate the azimuth misalignment angle, and finally feed it back to the north-seeking system to obtain an accurate north-seeking result. This embodiment uses east (X), north (Y) and sky (Z) as the coordinate system by default. The relationship between the coordinates and the carrier is: the Y axis points to the front, the X axis points to the right of the carrier, and the Z axis points to the sky.

[0052] exist Figure 3 In the process, first, the accelerometer and gyroscope will be calibrated at the factory for error compensation, that is, the modeling calibration zero bias, scale coefficient and installation error coefficient and other steps are adopted. The existing accelerometer error compensation and gyroscope error compensation can be directly adopted, which does not belong to the invention point and necessary technical features of this embodiment. Therefore, it will not be described in detail in this embodiment; then the fusion between the two is based on the dual-vector attitude determination principle, that is, the dual-vector attitude determination algorithm described above is adopted to perform indirect coarse alignment; and the specific force calculation is based on the proportional equation to update the speed and provide observations for the subsequent fine alignment. For details of this part, see the projection of the specific force output of the accelerometer in the b0 system described above. Through the attitude matrix Establish the relationship between gravity acceleration and specific force measurement value, etc. After the rough alignment is completed, a rough attitude matrix is ​​obtained, which is used as the initial attitude matrix for fine alignment. Entering the fine alignment stage, according to the state equation and measurement equation of the Kalman model, the attitude error is iteratively fed back to the attitude matrix, and finally the fine alignment is completed, and the attitude converges to a relatively accurate process.

[0053] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A three-axis north-seeking gyroscope, characterized in that: include: A mounting reference member, a connector, a first circuit board, a second circuit board, a third circuit board, a fourth circuit board, a fifth circuit board and a fixing cover, wherein the bottom of the mounting reference member is a mounting reference surface, an integrated mounting frame is arranged on the mounting reference surface, the mounting frame is arranged between the mounting reference member and the fixing cover, a first circuit board mounting step is arranged on the inner side of the bottom of the mounting frame, and the first circuit board is arranged on the first circuit board mounting step; a second circuit board mounting step is arranged on the inner side of the upper part of the mounting frame, the setting direction of the second circuit board mounting step is perpendicular to the setting direction of the first circuit board mounting step, and the second circuit board is arranged on the second circuit board mounting step; the third circuit board is arranged on the top of the mounting frame; a fourth circuit board mounting plane and a fifth circuit board mounting plane are arranged on two adjacent side surfaces of the mounting frame, the fourth circuit board and the fifth circuit board are arranged on the fourth circuit board mounting plane and the fifth circuit board mounting plane, respectively, and are perpendicular to the first circuit board respectively; the connector is arranged on the outer side of the mounting reference member, and is staggered with the fourth circuit board mounting plane and the fifth circuit board mounting plane.

2. The three-axis north-seeking gyroscope according to claim 1, characterized in that: The installation reference member is also provided with a fixing cover installation step, which is arranged on the inner side of the bottom of the fixing cover, and the shape and size of the fixing cover installation step are respectively matched with the shape and size of the fixing cover; the installation frame is arranged on the fixing cover installation step.

3. The three-axis north-seeking gyroscope according to claim 2, characterized in that: The side of the fixing cover mounting step is provided with an elastic outer edge, and the elastic outer edge is interference connected with the inner side of the bottom of the fixing cover; the mounting reference surface is provided with a first mounting hole, and the first mounting hole is provided on the outer side of the fixing cover mounting step, and the mounting reference surface is connected with the fixing cover through the first mounting hole.

4. The three-axis north-seeking gyroscope according to any one of claims 1 to 3, characterized in that: A connector mounting portion is provided on the side of the mounting reference member, a blocking piece is provided on the inner side of the connector mounting portion, and an mounting window is provided on the fixing cover. The position and size of the mounting window match the position and size of the connector mounting portion, and the blocking piece is embedded in the inner side of the mounting window.

5. The three-axis north-seeking gyroscope according to any one of claims 1 to 3, characterized in that: The fourth circuit board mounting plane and the fifth circuit board mounting plane are both concave-shaped mounting planes, and circuit board mounting holes are arranged on the ears on both sides of the mounting planes.

6. The three-axis north-seeking gyroscope according to any one of claims 1 to 3, characterized in that: A cable connection portion is disposed on one side of the second circuit board and one side of the third circuit board, and the positions of the cable connection portion are staggered with the positions of the connector, the fourth circuit board mounting plane, and the fifth circuit board mounting plane.

7. A north-seeking method for a three-axis north-seeking gyroscope, characterized in that: A three-axis north-seeking gyroscope as claimed in any one of claims 1 to 6 is used, and the following steps are included: Step S1, define the carrier coordinate system b0 and the navigation coordinate system n0 at the initial moment, and obtain the attitude matrix at the initial moment according to the orientation relationship between the carrier coordinate system b0 and the navigation coordinate system n0 Complete the first alignment; Step S2, establishing a Kalman filter model, performing zero-speed observation Kalman filter correction through the Kalman filter model, and achieving re-alignment to obtain a north-seeking result.

8. The north-seeking method of the three-axis north-seeking gyroscope according to claim 7, characterized in that: In step S1, after initialization, the gravity vector of a preset fixed point on the surface of the earth is observed from the navigation coordinate system n, the direction of the gravity vector points to the center of the earth, the direction of the rate of change of the gravity vector is the direction of the earth's rotation, the direction and the rate of change of the gravity vector are used as the horizontal and azimuth information of the preset fixed point, and the attitude matrix at the initial moment is obtained according to the dual-vector attitude determination algorithm.

9. The north-seeking method of the three-axis north-seeking gyroscope according to claim 7, characterized in that: The first alignment time of step S1 is extended according to a preset time threshold.

10. The north-seeking method of the three-axis north-seeking gyroscope according to claim 7, characterized in that: In step S2, the formula Establish a Kalman filter model, where is the east misalignment angle, is the north misalignment angle, is the celestial misalignment angle, δv e is the eastward velocity error, δv n is the north velocity error, δv u is the celestial velocity error, and is the random constant drift of the three-axis gyroscope, and is the equivalent accelerometer random constant drift; represents the differential of X; F represents the state transfer matrix, represents the cross product of the Earth's rotation vector; g n × represents the cross product of the gravitational acceleration vector; 0 3×3 Represents a 3 by 3 zero matrix; 0 6×12 Represents a 6 by 12 zero matrix; I 3×3 represents the 3×3 identity matrix; W represents the system state noise; V represents the system measurement noise.

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