A calibration device for a strapdown inertial measurement unit

Abstract

The application discloses a kind of calibration devices for strapdown inertial measurement unit, solve the technical problems of the prior art, such as large size and weight of calibration tool, poor stability, which affects the final test accuracy, and the need to replace the turntable with larger volume and load for overturning calibration, leading to increased resource costs, comprising a calibration bracket, four calibration bracket package angles and a positioning locking device.The calibration bracket is fixedly connected to the inertial measurement unit body through the positioning locking device.The calibration bracket is fixed on the inertial measurement unit body through the positioning locking device, achieving miniaturization design, reducing the weight of the calibration device by about 90%, reducing the volume by about 40%, and greatly saving the resource cost and labor cost of strapdown inertial measurement unit calibration work.

Description

Technical Field

[0001] This invention relates to a strapdown inertial navigation system (SINS) calibration fixture, specifically to a calibration device for SINS. Background Technology

[0002] As a key device in the navigation system, the error coefficient of the core instrument of the strapdown inertial group needs to be determined through calibration testing. During the system-level calibration of the strapdown inertial group, it is usually necessary to use a six-sided tooling or a dual-axis turntable to complete the rotation of the strapdown inertial group in 19 positions.

[0003] If a hexahedral fixture is used for manual flipping, the combined weight of the fixture and the strapdown inertial navigation system is too large, requiring multiple people to work together. Furthermore, the flipping process is unstable, affecting the final test accuracy. If a dual-axis turntable is used for flipping, it requires a large turntable with a high load capacity, increasing resource costs.

[0004] Chinese utility model patent CN206952818U discloses a strapdown inertial navigation system (INS) turntable calibration fixture, comprising a frame with an overall hexahedral shape. One side of the frame is a first mounting surface, and the frame is fixed to the turntable surface via the first mounting surface. A first positioning block is provided on the frame for positioning the frame on the turntable surface. At least two of the remaining sides of the frame are second mounting surfaces, and an inertial measurement unit (INS) is mounted on the strapdown INS turntable calibration fixture via the second mounting surfaces. The frame also has a second positioning block for positioning the INS on the frame, and weight-reduction holes are provided on the frame. Each of the four sides of the frame can mount an INS, enabling simultaneous calibration of four INS.

[0005] However, the hexahedral frame in the above-mentioned patented technology solutions is often large in size and weight, and the turntable required is larger than that of traditional turntables, which increases resource costs. Summary of the Invention

[0006] The purpose of this invention is to solve the technical problem that the calibration fixtures in the prior art are large in size and weight, requiring larger turntables and thus increasing resource costs, and to provide a calibration device for strapdown inertial navigation systems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A calibration device for a strapdown inertial navigation system (INS), the INS comprising an INS body, an external vibration damping system, and a mounting frame, wherein the INS body is mounted to the INS mounting position on the mounting frame via the external vibration damping system, and the external vibration damping system is located between the INS body and the mounting frame; the bottom of the mounting frame has four corners, each corner comprising two mutually perpendicular sides and a chamfer for connecting the two sides, and the two sides located on the same side of the INS body are in the same vertical plane; its special feature is that it includes a calibration bracket, four calibration bracket corner protectors, and a positioning and locking device;

[0009] The calibration bracket is fixedly connected to the inertial navigation system (INS) body to be tested via a positioning and locking device; the calibration bracket has four corner mounting positions on the side away from the INS body, and the four corner mounting positions of the calibration bracket are fixedly installed on the corner mounting positions respectively, and the maximum outer envelope of the four calibration brackets after corner mounting is greater than the maximum outer envelope of the calibration bracket.

[0010] Each of the four calibration bracket corners has a fixing part and a supporting part. One end of the fixing part is fixedly connected to the calibration bracket, and the other end is connected to the supporting part. The supporting part has a top supporting surface and at least two side supporting surfaces. The two adjacent supporting surfaces are perpendicular to each other, and a chamfer is provided at the connection of the two supporting surfaces. The side supporting surfaces of the two calibration bracket corners located on the same side of the inertial navigation system body are in the same vertical plane and are coplanar with the two vertical surfaces of the mounting bracket located on the corresponding side. The four top supporting surfaces are located in the same plane.

[0011] The fixing parts of the four calibration brackets at the corners are all metal, while their supporting parts are made of rubber. Defining the Shore hardness of the rubber as H, then... The value of M satisfies the following condition: when the strapdown inertial unit (INS) body is fixedly connected to the calibration support, and is in the calibration position, the deviation angle between the plane of the calibration position and the horizontal plane is . ,and .

[0012] Furthermore, a support member is embedded within the support portion, and the support member has through holes;

[0013] The fixing part has an inverted T-shaped structure, with its horizontal end fixedly connected to the calibration bracket and its vertical end extending into the support part; the screw passes through the through hole on the support member and is fixedly connected to the vertical end of the fixing part.

[0014] The support component is made of metal and is supported inside the support section.

[0015] Furthermore, the chamfers at the four corners of the mounting bracket are the same size as the chamfers at the connection between two adjacent support surfaces of the calibration bracket.

[0016] Furthermore, the deviation angle The calculation formula is:

[0017] ;

[0018] ;

[0019] ;

[0020] in, This represents the deformation of the support under the influence of gravity.

[0021] This refers to the assembly tolerance of the inertial navigation system (INS) body relative to the mounting bracket.

[0022] The total mass after the calibration device and strapdown inertial navigation system are installed;

[0023] It is the acceleration due to gravity;

[0024] The span between the center of mass and the mounting frame after the calibration device and strapdown inertial navigation system are installed;

[0025] K represents the static stiffness of the support component;

[0026] L is the span between the support and the mounting bracket.

[0027] Furthermore, the calibration bracket is manufactured using a molding process, in which the support component is pressed into the rubber support portion during manufacturing.

[0028] Furthermore, the rubber material of the support part of the calibration bracket at the corner is silicone rubber or nitrile rubber.

[0029] Furthermore, the support surface of the corner support of the calibration bracket is roughened.

[0030] Furthermore, the positioning and locking device includes two countersunk screws for positioning and two locking screws for locking, with the two countersunk screws and the two locking screws arranged diagonally.

[0031] Furthermore, the support portion of the calibration bracket has five support surfaces, and adjacent support surfaces are perpendicular to each other.

[0032] The beneficial effects of this invention are:

[0033] 1. The present invention provides a calibration device for strapdown inertial navigation systems (INS). By fixing the calibration bracket to the INS body through a positioning and locking device, a miniaturized design is achieved. The calibration device is reduced in weight by about 90% and in volume by about 40%, which greatly saves the resource and labor costs of strapdown INS calibration work.

[0034] 2. The present invention provides a calibration device for strapdown inertial navigation systems. By fixing four calibration bracket corners at the four corner mounting positions of the calibration bracket, the calibration bracket corners and the mounting frame jointly support the strapdown inertial navigation system and the calibration device, making the rotation process of the calibration device smooth and ensuring good consistency in repeated calibration.

[0035] 3. This invention provides a calibration device for strapdown inertial navigation systems (INS). After the INS and calibration device are installed, they are placed on a marble surface with a vertical support perpendicular to the marble surface. For INS without an internal vibration damping system, during calibration, flipping and translating the calibration device can cause the marble surface and vertical support to bypass the external vibration damping system and directly impact the inertial instruments inside the INS, thus affecting the accuracy of the calibration results. To solve this problem, the calibration bracket's corner is configured with a fixed part and a support part. The fixed part is a metal insert, improving the installation stability of the calibration bracket's corner and increasing calibration accuracy. The support part is designed as a rubber component, and one end of the fixed part is connected to the support part, so that the support part meets the rigidity requirements and has good vibration damping and buffering effects, ensuring calibration accuracy. Furthermore, to ensure the vibration damping effect of the support part, the Shore hardness of the rubber material is set to less than or equal to 65 degrees. Its minimum value must meet the requirement that, after the INS and calibration device are installed and in the calibration position, the deviation angle between the plane where the calibration position is located and the horizontal plane is [value missing]. ,and This improves calibration accuracy.

[0036] 4. The present invention provides a calibration device for strapdown inertial navigation systems, wherein the chamfered edges of the four corners of the mounting frame are the same size as the chamfered edges at the connection points of the two adjacent support surfaces of the calibration bracket, thereby ensuring continuity and stability during the rotation process in any of the three directions of the inertial navigation system's coordinate system.

[0037] 5. The present invention provides a calibration device for strapdown inertial navigation systems, which reduces the sliding resistance between the calibration device and the marble tabletop during translation by roughening the support surface of the corner support of the calibration bracket.

[0038] 6. The present invention provides a calibration device for strapdown inertial navigation systems, which uses two countersunk screws arranged diagonally to position the calibration bracket, ensuring consistency in repeated installation between the calibration bracket and the inertial navigation system body, and two locking screws arranged diagonally to lock the calibration bracket, resulting in high stability.

[0039] 7. The present invention provides a calibration device for strapdown inertial navigation systems. By calculating the deviation angle and replacing the calibration bracket with a suitable Shore hardness at the wrap angle, the accuracy of the calibration results is improved by 80%. Attached Figure Description

[0040] Figure 1 This is a three-dimensional structural diagram of an embodiment of a calibration device for a strapdown inertial navigation system according to the present invention and after the strapdown inertial navigation system is installed.

[0041] Figure 2 This is a bottom view of a support portion of a calibration bracket wrap angle in an embodiment of a calibration device for strapdown inertial navigation systems according to the present invention;

[0042] Figure 3 This is a front view of a support portion of a calibration bracket wrap angle in an embodiment of a calibration device for strapdown inertial navigation systems according to the present invention;

[0043] Figure 4 yes Figure 3 A sectional view;

[0044] Figure 5 This is an embodiment of the calibration device for strapdown inertial navigation systems of the present invention and a schematic diagram of the strapdown inertial navigation system in its flipped state after installation.

[0045] The attached figures are labeled as follows:

[0046] 1. Calibration bracket; 2. Calibration bracket wrap angle; 201. Support part; 202. Fixing part; 203. Support component; 3. Positioning and locking device; 4. Inertial navigation system body; 5. External vibration damping system; 6. Mounting bracket; 7. Vertical support surface. Detailed Implementation

[0047] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] like Figure 1 As shown in the figure, an embodiment of the present invention provides a calibration device for a strapdown inertial navigation system (INS). The INS includes an INS body 4, an external vibration damping system 5, and a mounting frame 6. The INS body 4 is mounted to the INS mounting position on the mounting frame 6 via the external vibration damping system 5, and the external vibration damping system 5 is located between the INS body 4 and the mounting frame 6. The bottom of the mounting frame 6 has four corners, each corner including two mutually perpendicular sides and a chamfer for connecting the two sides. The two sides located on the same side of the INS body 4 are in the same vertical plane. The calibration device for the strapdown INS includes a calibration bracket 1, four calibration bracket corner protectors 2, and a positioning and locking device 3.

[0049] The calibration bracket 1 is fixedly connected to the inertial navigation system (INS) body 4 to be tested via a positioning and locking device 3; the calibration bracket 1 is directly mounted on the INS body 4 to achieve a lightweight and compact design. The calibration bracket 1 has four corner mounting positions on the side away from the INS body 4. The four corner mounting positions 2 are fixedly mounted on these positions, and the maximum outer envelope of the four corner mounting positions 2 after installation is greater than the maximum outer envelope of the calibration bracket 1. The maximum outer envelope of the calibration bracket 1 is sufficient to allow the four corners to accommodate the corner mounting positions 2, and the calibration bracket 1 should not provide support when the calibration device is in the calibration position after installation. The design of the four corner mounting positions 2 ensures that the calibration device can be smoothly rotated in any direction.

[0050] like Figure 1-4 As shown, each of the four calibration bracket corners 2 has a fixing part 202 and a supporting part 201. One end of the fixing part 202 is fixedly connected to the calibration bracket 1, and the other end is connected to the supporting part 201. Each supporting part 201 has a top supporting surface and at least two side supporting surfaces. Adjacent supporting surfaces are perpendicular to each other, and a chamfer is provided at the connection between the two supporting surfaces. The side supporting surfaces of the two calibration bracket corners 2 located on the same side of the inertial navigation system 4 are in the same plane and coplanar with the two vertical sides of the mounting frame 6 located on the corresponding side. The four top supporting surfaces are in the same plane; and the chamfers of the four corners of the mounting frame 6 are the same size as the chamfers at the connection between the two adjacent supporting surfaces of the calibration bracket corners 2. This forms the maximum envelope of the entire device's length × width × height, ensuring no interference during manual rotation in any of the three directions of the coordinate system of the inertial navigation system 4. Through the design of the calibration bracket corners 2, a good calibration mechanical environment is provided for the inertial navigation system 4, ensuring the accuracy of the calibration results.

[0051] The fixing parts 202 of the four calibration brackets at the corner 2 are all metal parts, and their supporting parts 201 are made of rubber. If the Shore hardness of the rubber is defined as H, then... The value of M satisfies the following condition: when the inertial unit 4 of the strapdown inertial group is fixedly connected to the calibration support 1, the deviation angle between the plane of the calibration position and the horizontal plane at each calibration position is . ,and By providing an initial deviation angle for each calibration position, and by rationally designing the hardness parameters of the support 201 and the fit tolerances of the parts, it is ensured that the deformation and assembly errors of the support 201 do not affect the accuracy of the calibration results. The calculation formula is:

[0052] ;

[0053] ;

[0054] ;

[0055] like Figure 5 As shown, where, The deformation of the support 201 under the action of gravity;

[0056] The assembly tolerance of the inertial navigation system body 4 relative to the mounting bracket 6 is calculated based on the dimensional chain of the design drawings.

[0057] The total mass after the calibration device and strapdown inertial navigation system are installed;

[0058] It is the acceleration due to gravity;

[0059] The span between the center of mass and mounting frame 6 after the calibration device and strapdown inertial navigation system are installed;

[0060] K represents the static stiffness of the support 201;

[0061] L is the span between the support 201 and the mounting bracket 6.

[0062] When the fixing part 202 is connected to the supporting part 201, a molding process can be used to press the other end of the fixing part 202 into the rubber supporting part 201. The other end of the fixing part 202 can be a cylindrical section, a spherical shape, or a T-shape, or any other shape that can provide support.

[0063] In this embodiment, a support member 203 is embedded in the support part 201, and the support member 203 has a through hole; the fixing part 202 has an inverted T-shaped structure, its horizontal end is fixedly connected to the calibration bracket 1, and its vertical end extends into the support part 201. Screws pass through the through hole on the support member 203 and are fixedly connected to the vertical end of the fixing part 202. The support member 203 is made of metal and is supported in the support part 201.

[0064] The support part 201 of the calibration bracket corner 2 is made of wear-resistant rubber, generally silicone rubber or nitrile rubber, and its support surface is roughened to reduce the sliding resistance between the calibration device and the marble tabletop (the calibration device needs to be placed on the marble tabletop during the calibration process). The support part 201 of the calibration bracket corner 2 has five support surfaces, and adjacent support surfaces are perpendicular to each other.

[0065] The positioning and locking device 3 includes two countersunk screws for positioning and two locking screws for locking. The two countersunk screws and the two locking screws are arranged diagonally. The diagonally arranged countersunk screws fix and secure the position of the calibration bracket 1 and the inertial navigation system (INS) body by engaging with the 90-degree countersunk surface between them. The other two diagonally arranged locking screws can be pan head screws or other non-countersunk screws with a large clearance fit to the calibration bracket 1. The locking screws pass through the through hole of the calibration bracket 1 and are fastened to the INS body to increase stability. Since the same degree of freedom is repeatedly positioned by two or more positioning elements, it may lead to difficulties in workpiece installation or deformation. Therefore, the method of using two countersunk screws for diagonal positioning and two locking screws for locking ensures accurate positioning, stable fixation, and improved calibration accuracy.

[0066] like Figure 5 As shown, when the Z-axis is upward, the calibration device needs to be rotated ±90º around the X-axis or Y-axis. After rotation, the calibration device is moved along the horizontal plane of the marble to the vertical surface 7, which serves as the reference for each position during the calibration process. The same applies to other axes, and so on, until the 19 positions required for calibration are completed.

[0067] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A calibration device for a strapdown inertial navigation system (INS), the INS comprising an INS body (4), an external vibration damping system (5), and a mounting frame (6), wherein the INS body (4) is mounted to the INS mounting position of the mounting frame (6) via the external vibration damping system (5), and the external vibration damping system (5) is located between the INS body (4) and the mounting frame (6), the mounting frame (6) having four corners at its bottom, each corner comprising two mutually perpendicular sides and a chamfer for connecting the two sides, the two sides located on the same side of the INS body (4) being in the same vertical plane; characterized in that: It includes a calibration bracket (1), four calibration bracket wrap corners (2) and a positioning and locking device (3); The calibration bracket (1) is fixedly connected to the inertial navigation system body (4) to be tested through a positioning locking device (3); the calibration bracket (1) has four corner mounting positions on the side away from the inertial navigation system body (4), and the four calibration bracket corners (2) are fixedly installed on the corner mounting positions respectively. The maximum outer envelope of the four calibration bracket corners (2) after installation is greater than the maximum outer envelope of the calibration bracket (1). Each of the four calibration bracket corners (2) has a fixing part (202) and a supporting part (201). One end of the fixing part (202) is fixedly connected to the calibration bracket (1), and the other end is connected to the supporting part (201). The supporting part (201) has a top supporting surface and at least two side supporting surfaces. The two adjacent supporting surfaces are perpendicular to each other, and a chamfer is provided at the connection of the two supporting surfaces. The side supporting surfaces of the two calibration bracket corners (2) located on the same side of the inertial navigation system (4) are in the same vertical plane and are coplanar with the two vertical surfaces of the mounting bracket (6) located on the corresponding side. The four top supporting surfaces are in the same plane. The fixing parts (202) of the four calibration bracket wrap angles (2) are all metal parts, and their supporting parts (201) are made of rubber. The Shore hardness of the rubber is defined as H. Therefore, The value of M satisfies the following condition: when the strapdown inertial group body (4) is fixedly connected to the calibration support (1), the deviation angle between the plane of the calibration position and the horizontal plane at each calibration position is . ,and .

2. The calibration device for strapdown inertial navigation systems according to claim 1, characterized in that: The support part (201) is inlaid with a support member (203), and the support member (203) is provided with a through hole; The fixing part (202) has an inverted T-shaped structure. Its horizontal end is fixedly connected to the calibration bracket (1), and its vertical end extends into the support part (201). The screw passes through the through hole on the support (203) and is fixedly connected to the vertical end of the fixing part (202). The support member (203) is made of metal and is supported inside the support part (201).

3. The calibration device for strapdown inertial navigation systems according to claim 1, characterized in that: The chamfers at the four corners of the mounting bracket (6) are the same as the chamfers at the connection between the two adjacent support surfaces of the calibration bracket corner (2).

4. The calibration device for strapdown inertial navigation systems according to claim 1, characterized in that: Deviation angle The calculation formula is: ； ； ； in, The deformation of the support (201) under the action of gravity; The assembly tolerance of the inertial navigation system (4) relative to the mounting bracket (6); The total mass after the calibration device and strapdown inertial navigation system are installed; It is the acceleration due to gravity; The distance between the center of mass and the mounting frame (6) after the calibration device and strapdown inertial navigation system are installed; K is the static stiffness of the support (201); L is the span between the support (201) and the mounting bracket (6).

5. The calibration device for strapdown inertial navigation systems according to claim 2, characterized in that: The calibration bracket wrap angle (2) is made by molding process, and the support (203) is pressed into the rubber support part (201) during the manufacturing process.

6. The calibration device for strapdown inertial navigation systems according to claim 1, characterized in that: The rubber material of the support part (201) of the calibration bracket wrap angle (2) is silicone rubber or nitrile rubber.

7. The calibration device for strapdown inertial navigation systems according to claim 6, characterized in that: The support surface of the support part (201) of the calibration bracket wrap angle (2) is roughened.

8. The calibration device for strapdown inertial navigation systems according to claim 1, characterized in that: The positioning and locking device (3) includes two countersunk screws for positioning and two locking screws for locking. The two countersunk screws are arranged diagonally, and the two locking screws are arranged diagonally.

9. The calibration device for strapdown inertial navigation systems according to claim 1, characterized in that: The support portion (201) of the calibration bracket wrap angle (2) has five support surfaces, and two adjacent support surfaces are perpendicular to each other.

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