A shock absorber locking device for inertial measurement unit calibration

Abstract

This invention discloses a damper locking device for calibrating an inertial measurement unit (IMU) assembly. The device is characterized by comprising a double-ended stud screw, a fixing ring I, a fixing ring II, and a locking nut. The two ends of the double-ended stud screw are respectively provided with a first stud and a second stud. The first stud passes through an external damper to fix the IMU assembly to an external carrier. The fixing ring I and fixing ring II combine to form a ring, which is detachably connected. The ring is inserted between the IMU assembly and the carrier. The locking nut is screwed into the second stud of the double-ended stud screw to press the IMU assembly firmly. This invention enables calibration of IMU assemblies with damping without disassembling the damper, solving the problem of low calibration accuracy for internally damped IMU assemblies in existing methods. It also has minimal impact on the thermal conductivity of the assembly, ensuring accurate temperature modeling.

Description

Technical Field

[0001] This invention relates to a damper locking device for inertial measurement assembly calibration, belonging to the field of inertial measurement. Background Technology

[0002] Inertial measurement units (IMUs) typically consist of gyroscopes, accelerometers, and corresponding circuit boards and structural components. They are used to measure the linear and angular motion information of a vehicle, providing crucial motion information and playing an extremely important role in vehicles across land, sea, air, and space.

[0003] Harsh mechanical environments can lead to decreased accuracy or even failure of inertial measurement units (IMUs). Therefore, when the vibration and impact levels in the working environment are high, IMUs are often subjected to overall vibration damping to reduce the impact of the mechanical environment. Vibration dampers are elastic elements, and their deformation during IMU calibration can introduce calibration errors. To address this issue, a high-stiffness metal equivalent with the same dimensions and interface as the vibration damper is typically used instead during calibration. After calibration, the metal equivalent is then replaced with a vibration damper for further testing. However, this method has several problems. First, for IMUs using internal vibration damping, due to limitations such as size, there is usually no internal mounting reference for the damped instrument components. Therefore, replacing the metal equivalent with a vibration damper changes the positional relationship of the instrument components relative to the external mounting reference, leading to deviations in the parameters calibrated using the metal equivalent and reducing the accuracy of the IMU. Secondly, the thermal conductivity of the metal equivalent is much higher than that of the vibration damper. When using the metal equivalent for calibration, the heat conduction of the inertial measurement unit differs significantly from that of the actual vibration damper in use, resulting in inaccurate temperature modeling during calibration. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a damper locking device for inertial measurement unit calibration, which has little impact on the thermal conductivity of the unit and can ensure the accuracy of temperature modeling and the precision requirements of inertial measurement unit calibration.

[0005] The present invention solves the above-mentioned technical problem through the following technical solution:

[0006] This invention discloses a damper locking device for inertial measurement unit calibration, characterized in that it includes a double-ended stud screw 1, a retaining ring I2, a retaining ring II3, and a locking nut 4;

[0007] The double-ended stud screw 1 has a first stud and a second stud at its two ends, respectively. The first stud passes through the external vibration damper to fix the external inertial measurement unit to the external carrier. The fixing ring I2 and fixing ring II3 are combined to form a ring, which is detachably connected. The ring is inserted between the inertial measurement unit and the carrier. The locking nut 4 is screwed into the second stud of the double-ended stud screw 1 to press the inertial measurement unit tightly. The difference between the inner diameter of the fixing ring I2 and the outer diameter of the vibration damper is b1, and the height difference between the height of the fixing ring I2 and the height between the inertial measurement unit and the carrier is h1.

[0008] In the above-mentioned shock absorber locking device, the double-ended stud screw 1 is a hexagonal prism and is a one-piece molded part; the fixing ring I2, fixing ring II3 and locking nut 4 are all one-piece molded parts.

[0009] In the above-mentioned shock absorber locking device, the locking nut 4 has a threaded hole inside, and the top of the first stud has a slot for fixing the locking nut 4. The slot matches the structure of the threaded hole of the locking nut 4.

[0010] In the above-mentioned damper locking device, the strength of the second stud meets the stress requirement that it will not break under the specified mechanical environment.

[0011] In the above-mentioned shock absorber locking device, the fixing ring I2 is a semi-circular ring structure, with a rectangular lug connected to the tail of the semi-circular ring, and a 90° countersunk hole in the center of the lug.

[0012] In the above-mentioned shock absorber locking device, the fixing ring II3 is a semi-circular ring structure, with a rectangular lug connected to the tail of the semi-circular ring, and a threaded hole in the center of the lug.

[0013] In the above-mentioned shock absorber locking device, the locking nut 4 is cylindrical, with a threaded hole and a slot in the center of the bottom surface, and multiple notches evenly distributed around the top surface for observing the condition of the shock absorber.

[0014] In the above-mentioned damper locking device, the countersunk hole of the fixing ring I2 matches the structure of the threaded hole of the fixing ring II3.

[0015] In the above-mentioned shock absorber locking device, b1 > 0.5 mm, h1 = 0.2~0.5 mm; the difference between the inner diameter of the locking nut 4 and the outer diameter of the shock absorber is greater than 0.5 mm.

[0016] In the above-mentioned shock absorber locking device, the thermal conductivity of the materials used for the double-ended stud screw 1, the fixing ring I2, the fixing ring II3 and the locking nut 4 is less than 20 W / m·K, and the yield strength is greater than 300 MPa.

[0017] In the above-mentioned damper locking device, the flatness of the upper and lower end faces of the fixing ring II3 is better than 0.008mm, the roughness is better than 0.8μm, and the parallelism between the upper and lower end faces is better than 0.01mm; the flatness of the bottom and top surfaces of the locking nut 4 is better than 0.008mm, the roughness is better than 0.8μm, and the parallelism between the bottom and top surfaces is better than 0.01mm; the flatness of the upper and lower end faces of the fixing ring I2 is better than 0.008mm, the roughness is better than 0.8μm, and the parallelism between the upper and lower end faces is better than 0.01mm.

[0018] The advantages of this invention compared to the prior art are:

[0019] (1) The locking device designed in this invention achieves a rigid connection between the inertial measurement assembly and the carrier by locking the damper, and its installation and disassembly can be carried out in the normal installation state of the damper without disassembling the damper, thus solving the problem of low calibration accuracy of the internal damping inertial measurement assembly in the existing method.

[0020] (2) The thermal conductivity of the materials of each part of the locking device designed in this invention is less than 20 W / m·K, which has little impact on the combined thermal conductivity and can ensure the accuracy of temperature modeling.

[0021] (3) The locking device designed in this invention has high strength and high precision in the fixing ring I, fixing ring II and locking nut, which can meet the accuracy requirements of inertial measurement assembly calibration. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the application of the shock absorber locking device provided by the present invention;

[0023] Figure 2 This is a cross-sectional schematic diagram of the application of the shock absorber locking device provided by the present invention;

[0024] Figure 3 A schematic diagram of the double-ended stud screw provided by the present invention;

[0025] Figure 4 This is a schematic diagram of the fixing ring I provided by the present invention;

[0026] Figure 5 A schematic diagram of the fixing ring II (3) provided by the present invention;

[0027] Figure 6 A schematic diagram of the locking nut (4) provided by the present invention;

[0028] Figure 7 This is a cross-sectional schematic diagram of the locking nut (4) provided by the present invention. Detailed Implementation

[0029] like Figure 1 and Figure 2 As shown, this embodiment discloses a damper locking device for inertial measurement unit calibration, including: a double-ended stud screw 1, a retaining ring I2, a retaining ring II3, and a locking nut 4;

[0030] The double-ended stud screw 1 has a first stud and a second stud at its two ends, respectively. The first stud passes through the external vibration damper to fix the external inertial measurement unit to the external carrier. The fixing ring I2 and fixing ring II3 are combined to form a ring, which is detachably connected. The ring is inserted between the inertial measurement unit and the carrier. The locking nut 4 is screwed into the second stud of the double-ended stud screw 1 to press the inertial measurement unit tightly. The inner diameter of the fixing ring I2 is greater than the outer diameter b1 of the vibration damper, and the height of the fixing ring I2 is h1 higher than the height between the inertial measurement unit and the carrier.

[0031] like Figure 3 As shown, the double-ended stud screw 1 is a hexagonal prism and is a one-piece molded part; the retaining ring I2, retaining ring II3 and locking nut 4 are all one-piece molded parts.

[0032] The locking nut 4 has a threaded hole inside, and the top of the first stud has a slot for fixing the locking nut 4. The specifications of the slot are the same as those of the threaded hole of the locking nut 4.

[0033] The strength of the second stud meets the stress requirement that it will not break under the specified mechanical environment.

[0034] like Figure 4 As shown, the fixing ring I2 is a semi-circular ring structure. The tail of the semi-circular ring is connected to a rectangular ear piece, and a 90° countersunk hole is opened in the center of the ear piece.

[0035] like Figure 5 As shown, the fixing ring II3 is a semi-circular ring structure, with a rectangular lug connected to the tail of the semi-circular ring, and a threaded hole in the center of the lug.

[0036] like Figure 6 and Figure 7 As shown, the locking nut 4 is cylindrical, with a threaded hole and a slot in the center of the bottom surface, and multiple notches evenly distributed around the top surface for observing the condition of the shock absorber.

[0037] The countersunk hole specification of the retaining ring I2 matches the threaded hole specification of the retaining ring II3. The inner diameter of the retaining ring I2 is b1>0.5mm larger than the outer diameter of the shock absorber, and the height is h1=0.2~0.5mm higher than the height between the inertial measurement assembly and the carrier; the inner diameter of the locking nut 4 is more than 0.5mm larger than the outer diameter of the shock absorber.

[0038] The materials used for the double-ended stud screw 1, the retaining ring I2, the retaining ring II3, and the locking nut 4 have a thermal conductivity of less than 20 W / m·K and a yield strength of greater than 300 MPa.

[0039] The flatness of the upper and lower end faces of the fixing ring II3 is better than 0.008 mm, the roughness is better than 0.8 μm, and the parallelism between the upper and lower end faces is better than 0.01 mm; the flatness of the bottom and top surfaces of the locking nut 4 is better than 0.008 mm, the roughness is better than 0.8 μm, and the parallelism between the bottom and top surfaces is better than 0.01 mm; the flatness of the upper and lower end faces of the fixing ring I2 is better than 0.008 mm, the roughness is better than 0.8 μm, and the parallelism between the upper and lower end faces is better than 0.01 mm.

[0040] Example 1

[0041] The inertial measurement unit being damped weighs 1.7 kg and is damped by a four-point rubber vibration damper at the waist. The outer diameter of the damper is Φ14.5 mm, and the height of the lower half of the damper, i.e. the height between the inertial measurement unit and the carrier, is 7 mm.

[0042] The double-ended stud screw 1 consists of two studs connected to the upper and lower ends of a hexagonal prism. The upper stud is M4 with a slotted top, and the lower stud is M5. It is a one-piece molded part made of titanium alloy TC4 with a thermal conductivity of 7.96 W / m·K and a yield strength of 825 MPa.

[0043] The retaining ring I2 consists of a semi-circular ring connected to a rectangular lug at the end. A 90° countersunk hole with a diameter of 3.3mm and a diameter of 6mm × 90° is formed in the center of each lug. It is a one-piece molded part made of titanium alloy TC4 with a thermal conductivity of 7.96 W / m·K and a yield strength of 825 MPa. The retaining ring I2 has an inner diameter of 15mm, a height of 7.2mm, a flatness of 0.008mm on both the upper and lower end faces, a roughness of 0.8μm, and a parallelism of 0.01mm between the upper and lower end faces.

[0044] The retaining ring II3 consists of a semi-circular ring connected to a rectangular lug at the end. An M3 threaded hole is located in the center of each lug. It is a one-piece molded part made of titanium alloy TC4, with a thermal conductivity of 7.96 W / m·K and a yield strength of 825 MPa. The retaining ring II3 has an inner diameter of Φ15 mm, a height of 7.2 mm, a flatness of 0.008 mm on both the upper and lower end faces, a roughness of 0.8 μm, and a parallelism of 0.01 mm between the upper and lower end faces.

[0045] The locking nut 4 is cylindrical with an M4 threaded hole in the center of its bottom surface and a slotted groove. It is a one-piece molded part made of titanium alloy TC4, with a thermal conductivity of 7.96 W / m·K and a yield strength of 825 MPa. The inner diameter of the locking nut 4 is Φ15 mm. The flatness of the bottom and top surfaces of the locking nut 4 is 0.008 mm, the roughness is 0.8 μm, and the parallelism between the bottom and top surfaces is 0.01 mm.

[0046] The process of using the shock absorber locking device is as follows: First, use a double-ended stud screw 1 to fix the inertial measurement unit (IMU) onto the carrier through the shock absorber; Second, insert the fixing ring I2 and fixing ring II3 between the external mounting lugs of the IMU and the carrier, respectively, and combine them into a complete ring. Use an M3 countersunk screw to fix the two together, thus restricting the downward movement of the IMU relative to the carrier; Third, screw the locking nut 4 into the upper stud of the double-ended stud screw 1 to press the IMU together, thus restricting the movement of the IMU relative to the carrier in all directions, achieving a rigid connection between the IMU and the carrier, and avoiding calibration errors caused by shock absorber deformation.

[0047] After calibration, remove the damper locking device: First, unscrew the locking nut 4. Second, unscrew the M3 countersunk screws that fix the retaining ring I2 and retaining ring II3. Then remove the two retaining rings respectively. This completes the disassembly of the damper locking device. The inertial measurement assembly can then carry out other tests normally. The double-ended stud screw 1 continues to be used as a fastener for the damper and becomes a formal part of the inertial measurement assembly.

[0048] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A damper locking device for inertial measurement unit calibration, characterized in that: Includes a double-ended stud screw (1), retaining ring I (2), retaining ring II (3), and a lock nut (4); The double-ended stud screw (1) has a first stud and a second stud at its two ends respectively. The first stud passes through the external damper to fix the external inertial measurement assembly to the external carrier. The fixing ring I (2) and fixing ring II (3) are combined to form a ring, which is detachably connected. The ring is inserted between the inertial measurement assembly and the carrier. The locking nut (4) is screwed into the second stud of the double-ended stud screw (1) to press the inertial measurement assembly. The difference between the inner diameter of the fixing ring I (2) and the outer diameter of the damper is b1. The height difference between the height of the fixing ring I (2) and the height between the inertial measurement assembly and the carrier is h1. b1 > 0.5 mm, and h1 = 0.2 ~ 0.5 mm. The difference between the inner diameter of the locking nut (4) and the outer diameter of the damper is greater than 0.5 mm.

2. The damper locking device for inertial measurement unit calibration according to claim 1, characterized in that: The double-ended stud screw (1) is a hexagonal prism and is a one-piece molded part; the retaining ring I (2), retaining ring II (3) and locking nut (4) are all one-piece molded parts.

3. A damper locking device for inertial measurement unit calibration according to claim 1, characterized in that: The locking nut (4) has a threaded hole inside, and the top of the first stud has a slot for fixing the locking nut (4). The slot matches the threaded hole structure of the locking nut (4).

4. A damper locking device for inertial measurement unit calibration according to claim 1, characterized in that: The strength of the second stud meets the stress requirement that it will not break under the specified mechanical environment.

5. A damper locking device for inertial measurement unit calibration according to claim 1, characterized in that: The fixing ring I (2) is a semi-circular ring structure. The tail of the semi-circular ring is connected to a rectangular ear piece, and a 90° countersunk hole is opened in the center of the ear piece.

6. A damper locking device for inertial measurement unit calibration according to claim 1, characterized in that: The fixing ring II (3) is a semi-circular ring structure. The tail of the semi-circular ring is connected to a rectangular ear piece, and the ear piece has a threaded hole in the center.

7. A damper locking device for inertial measurement unit calibration according to claim 1, characterized in that: The locking nut (4) is cylindrical, with a threaded hole and a slotted groove in the center of the bottom surface, and multiple notches evenly distributed around the top surface for observing the condition of the shock absorber.

8. A damper locking device for inertial measurement unit calibration according to claim 1, characterized in that: The countersunk hole of the fixed ring I (2) matches the structure of the threaded hole of the fixed ring II (3).

9. A damper locking device for inertial measurement unit calibration according to claim 1, characterized in that: The materials used for the double-ended stud screw (1), the retaining ring I (2), the retaining ring II (3) and the locking nut (4) have a thermal conductivity of less than 20 W / m·K and a yield strength of greater than 300 MPa.

10. A damper locking device for inertial measurement unit calibration according to claim 1, characterized in that: The flatness of the upper and lower end faces of the fixing ring II (3) is better than 0.008 mm, the roughness is better than 0.8 μm, and the parallelism between the upper and lower end faces is better than 0.01 mm; the flatness of the bottom and top surfaces of the locking nut (4) is better than 0.008 mm, the roughness is better than 0.8 μm, and the parallelism between the bottom and top surfaces is better than 0.01 mm; the flatness of the upper and lower end faces of the fixing ring I (2) is better than 0.008 mm, the roughness is better than 0.8 μm, and the parallelism between the upper and lower end faces is better than 0.01 mm.

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