CN113720328B - An installation device and method for an accelerometer assembly in an inertial measurement unit - Google Patents

Abstract

The invention discloses a device and a method for installing an accelerometer component in an inertial measurement unit. The positions of the two accelerometer component mounting bosses can be adjusted by adjusting the screw rod and the measuring ruler in an iterative mode until the mounting error calibration result meets the index requirement, and meanwhile, the device can be adapted to IMU products of different models, and has strong operability and universality. The device and the method for installing the accelerometer component are beneficial to improving the installation precision of the accelerometer component for the IMU component, are beneficial to meeting the related installation error requirement of an IMU product, improve the calibration consistency of the installation errors before and after assembly and disassembly, and are convenient for reworking and repairing the product.

Description

An installation device and method for an accelerometer assembly in an inertial measurement unit

technical field

The invention relates to an installation device and method of an accelerometer component in an inertial measurement unit, belonging to the technical field of mechanical assembly.

Background technique

The inertial measurement unit (IMU) is one of the important measurement components of the GNC subsystem of the landing patrol vehicle entry module. The IMU measures the acceleration and angular acceleration information of the entry cabin along the IMU installation direction, and obtains the acceleration and angular acceleration information in the body coordinate system of the entry cabin through coordinate conversion, and then obtains the attitude and orbit information of the entry cabin. When Mars enters the aerodynamic deceleration phase, the IMU needs to be able to provide accurate measurement information to ensure the attitude and orbit control accuracy during the deceleration phase. During the period from entering the atmosphere of Mars to the start of the ranging and speed sensor, the IMU is able to obtain the attitude of entering the cabin. Therefore, according to the above requirement analysis, it can be seen that there is a high requirement for the measurement accuracy of the inertial measurement unit.

When the accelerometer in the inertial measurement unit measures the acceleration, in addition to the installation deviation between the input axis of the accelerometer component itself and the nominal value, there will also be a certain installation error between the accelerometer component and the IMU outer bracket. Due to the existence of the installation error, It will cause the accelerometer to have a corresponding output value at the zero position, that is, the zero bias of the accelerometer. The zero bias and zero bias stability of the accelerometer are very important performance indicators to measure the measurement accuracy of the accelerometer. According to the requirements for the measurement accuracy of the accelerometer, the installation error angle between the IMU outer bracket installation reference and the accelerometer assembly is required to be 6 months The amount of change is less than 30". At present, the calibration method is generally used to measure the installation error. In principle, the size is calculated by the transformation of the coordinate system matrix, but only relying on the calibration method has the following two problems:

On the one hand, according to the structure of the inertial measurement unit, when the accelerometer assembly is installed on the IMU outer bracket, there is no installation reference, which will lead to a large installation error angle. If the installation error calibration result does not meet the requirements, the accelerometer assembly needs to be re-test Installation, long time cycle, low assembly efficiency;

On the other hand, the calibration test does not correct the installation of the accelerometer assembly itself, but only serves as a judgment on whether the installation error meets the requirements, and the calibration result will be affected by the calibration accuracy, and the requirements for the calibration method will also be relatively high. High, and this usually makes the calibration method more complicated, resulting in long calibration time and low calibration efficiency.

Contents of the invention

The technology of the present invention solves the problem: overcomes the deficiencies of the prior art, and provides an installation method for reference transmission for the lack of installation reference of the accelerometer assembly, designs a corresponding installation device, and establishes an installation reference for the accelerometer assembly, which can The installation accuracy of the accelerometer assembly is improved, repeated clamping is avoided, and efficient assembly is ensured. The device has considerable versatility and high reliability, making the accelerometer assembly easy to assemble and maintain.

The technical solution of the present invention is: a mounting device for an accelerometer assembly in an inertial measurement unit, which includes a first mounting support, a second mounting support, a base, a reference boss, a first screw rod, a second screw rod, The first measuring ruler, the second measuring ruler;

The base is a rectangular parallelepiped box, and the planes formed by length and width are recorded as upper and lower surfaces, the planes formed by width and height are recorded as left and right sides, and the planes formed by length and height are recorded as inner and outer surfaces ; The first measuring ruler is coaxially fixedly connected with the first screw rod to form the first adjusting rod; the second measuring ruler is coaxially fixedly connected with the second screw rod to form the second adjusting rod; the first adjusting rod and the second adjusting rod Parallel, passing through the middle of the base, the ends of the first measuring ruler and the second measuring ruler expose the inner side of the base; the first screw rod and the second screw rod expose the outer side of the base;

The lower bottom surface of the base is fixedly connected with the reference boss, which is an integrated structure. The inner surface of the reference boss is perpendicular to the lower bottom surface of the base, and is used to fit the reference surface of the outer bracket of the inertial measurement unit. The upper surface and the lower surface of the base are set There are mounting holes matching the mounting holes on the frame of the outer bracket of the inertial measurement unit, which are used to fasten the base on the outer bracket of the inertial measurement unit. By adjusting the distance between the first screw rod and the second screw rod relative to the outer surface of the base, it can Adjust the distance between the first measuring ruler and the second measuring ruler relative to the inner surface of the base;

One end of the first installation support is fixedly connected to the first measuring ruler through screws, and an L-shaped notch is engraved on the other end, which is recorded as the first bracket slot; one end of the second installation support is fixedly connected to the second measuring ruler through screws, and the other end is engraved with There is an L-shaped notch, which is recorded as the second bracket slot; the first bracket slot and the second bracket slot are used to provide a reference for the installation of the accelerometer assembly.

Preferably, the first screw rod and the second screw rod are fastened to the base on the outer side of the base through nuts.

Preferably, the top surface of the L-shaped notch of the first bracket slot and the second bracket slot is parallel to the upper surface and the lower surface of the base, the side surfaces are parallel to the inner side of the reference boss, and the depth of the top surface along the length direction of the base is Not less than the width of the frame of the accelerometer component bracket, so that the surface of the card slot can be closely attached to the upper surface of the outer frame of the accelerometer component bracket, and the parallelism between the sides of the first bracket card slot and the second bracket card slot and the inner surface of the reference boss The error is less than 0.01mm.

Preferably, the height of the reference boss is not less than the width of the installation reference surface of the outer bracket of the inertial measurement unit, so that the installation reference surface can be completely attached to the inner surface of the reference boss.

Preferably, the width of the base is not less than the distance between the mounting holes on the two side frames of the outer frame of the inertial measurement unit, and the thickness is not less than the diameters of the first screw rod and the second screw rod.

Another technical solution provided by the present invention is: a method for installing an accelerometer assembly in an inertial measurement unit, the method comprising the following steps:

S1. Fit the inner surface of the reference boss with the reference surface on the frame of the outer frame of the inertial measurement unit, and at the same time, fit the lower surface of the device base with the upper surface of the frame of the outer frame of the inertial measurement unit, and align the mounting holes at the corresponding positions of the two , use screws to fix the base of the device on the frame of the outer bracket;

S2. Define the inner surface of the base as the zero-scale reference plane. In the initial state, adjust the zero-scale lines of the first measuring ruler and the second measuring ruler to be aligned with the zero-scale reference plane, and use screws to support the first installation of the accelerometer assembly and the second mounting support are respectively installed on the first measuring ruler and the second measuring ruler but are not fastened;

S3. Simultaneously adjust the first screw rod and the second screw rod so that the first bracket slot and the second bracket slot are in contact with the frame of the accelerometer assembly bracket closest to the reference plane on the frame of the outer bracket of the inertial measurement unit. The scales of the first measuring ruler and the second measuring ruler are the same relative to the zero-scale reference plane, so as to ensure that the first mounting support and the second mounting support have the same precession amount, and ensure that the provided accelerometer mounting reference plane and the mounting reference of the outer bracket The planes are parallel, after confirming the positions of the first mounting support and the second mounting support, fasten them, and then fasten the first screw rod and the second screw rod from the outer side of the base with nuts;

S4. Adjust the bracket of the acceleration component so that the upper surface of the frame fits the top surface of the first bracket slot and the top surface of the second bracket slot, and the outer side fits the sides of the first bracket slot and the second bracket slot. Based on this Complete the determination of the position of the accelerometer assembly, and then fasten the accelerometer assembly;

S5. After the accelerometer assembly is installed, the installation device is removed from the outer bracket.

Compared with the prior art, the present invention has the following advantages:

(1), the installation methods of the existing accelerometer components are all directly installed, and then the calibration method is used to measure the installation error. The calibration method and parts have high requirements for machining accuracy and strong dependence. The present invention is an accelerometer component. The installation reference is provided during assembly, which plays a corrective role in the installation of the accelerometer components, instead of relying only on the means of subsequent calibration, it can weaken the influence of installation errors in the initial state of installation, and improves the calibration compared with the existing technology efficiency.

(2) During the product rework process, the accelerometer components may be repeatedly disassembled and assembled. Recalibration is required after each disassembly and assembly. Due to factors such as labor, environment, and equipment, the accelerometer components will be installed before and after disassembly. Error calibration results There is a large discrepancy problem, and the present invention can effectively reduce installation errors, improve calibration consistency, ensure the accuracy and reliability of accelerometer assembly installation, and facilitate product maintenance.

(3) Whether the installation of the accelerometer assembly is qualified or not depends on the calibration result of the installation error. The present invention can avoid repeated mounting of the accelerometer assembly, greatly reduce the number of installations, and effectively solve the problem of failure of the installation error calibration test result to meet the requirements. The problem that the accelerometer assembly needs to be disassembled again has effectively improved the installation efficiency of the accelerometer assembly.

(4), the present invention can adjust accelerometer assembly installation boss position according to the accelerometer assembly configuration that needs to be installed, grasp the displacement of two bosses according to measuring ruler, make draw-in groove surface and accelerometer bracket frame realize relatively Good fit, allowing for precise mounting of the accelerometer assembly. The device can be applied to different types of IMU products, and has a compact structure, easy to assemble and disassemble, and has strong versatility and operability.

Description of drawings

Figure 1 is a schematic diagram of the installation position of the outer bracket of the inertial measurement unit and the accelerometer assembly;

Fig. 2 is a structural representation of the present invention;

Fig. 3 is the schematic diagram of adjusting screw rod;

Fig. 4 is a working principle diagram of the present invention and the installation reference of the outer support;

Fig. 5 is the working principle diagram of the present invention and accelerometer assembly bracket;

Detailed ways

The present invention is described in further detail below in conjunction with accompanying drawing:

The present invention designs an installation device and method for an accelerometer component in an inertial measurement unit. The device uses the installation reference of the outer bracket of the inertial measurement unit to provide a reference plane for the accelerometer component through the transmission of the installation device, ensuring the accuracy of the accelerometer. The installation can correct the installation error between the accelerometer component and the installation reference of the IMU outer bracket, which is conducive to meeting the installation error requirements, can effectively reduce the number of installations, and improve installation efficiency.

As shown in Figure 2, a mounting device for an accelerometer assembly in an IMU, the device includes a first mounting support 1-1, a second mounting support 1-2, a base 2, a reference boss 3, and a first screw rod 4-1 , the second screw rod 4-2, the first measuring ruler 5-1, the second measuring ruler 5-2;

The base 2 is a cuboid box-shaped part, the plane formed by length and width is recorded as upper surface and lower surface, the plane formed by width and height is recorded as left side and right side, and the plane formed by length and height is recorded as inner side and outer surface Side; the first measuring ruler 5-1 is coaxially fixedly connected with the first screw rod 4-1 to form the first adjusting rod; the second measuring ruler 5-2 is coaxially fixedly connected with the second screw rod 4-2 to form the second Two adjustment rods; the first adjustment rod is parallel to the second adjustment rod, passes through the middle of the base 2, and the ends of the first measuring ruler 5-1 and the second measuring ruler 5-2 expose the inner surface of the base 2; the first spiral The rod 4-1 and the second screw rod 4-2 expose the outer side of the base 2;

The lower bottom surface of the base 2 is fixedly connected with the reference boss 3, which is an integrated structure. The inner surface of the reference boss 3 is perpendicular to the lower bottom surface of the base, and is used to fit the reference surface of the outer bracket of the inertial measurement unit. The upper bottom surface of the base 2 and the lower bottom surface are provided with mounting holes matching the mounting holes on the frame of the outer frame of the inertial measurement unit, for fastening the base 2 on the outer frame of the inertial measurement unit, by adjusting the first screw rod 4-1 and the second screw rod 4 -2 the distance relative to the outer surface of the base 2, the distance between the first measuring ruler 5-1 and the second measuring ruler 5-2 relative to the inner surface of the base 2 can be adjusted;

One end of the first installation support 1-1 is fixedly connected to the first measuring ruler 5-1 by screws, and the other end is engraved with an L-shaped notch, which is recorded as the first bracket slot 6-1; one end of the second installation support 1-2 passes through The screw is firmly connected with the second measuring ruler 5-2, and the other end is engraved with an L-shaped notch, which is recorded as the second bracket slot 6-2; the first bracket slot 6-1 and the second bracket slot 6-2 are used for Provides a baseline for mounting the accelerometer assembly.

As shown in Figure 3, preferably, the first adjusting screw rod 4-1 and the second adjusting screw rod 4-2 are external screw cylinders, and the first adjusting screw rod 4-1 and the second adjusting screw rod 4-2 The outer surface of the base 2 is fastened with the base 2 through nuts. The top surfaces of the first measuring ruler 5-1 and the second measuring ruler 5-2 are provided with threaded holes of corresponding sizes for installing the accelerometer assembly and installing the first mounting support 1-1 and the second mounting support 1-2. The scale ranges of the first measuring ruler 5-1 and the second measuring ruler 5-2 are determined by the relative installation positions of the accelerometer assembly and the outer support, and the step length is set according to the requirements of the installation error index.

Preferably, the top surface of the L-shaped notch of the first support slot 6-1 and the second support slot 6-2 is parallel to the upper surface and the lower surface of the base 2, and the side surfaces are parallel to the inner surface of the reference boss 3 , the depth of the top surface along the length direction of the base 2 is not less than the frame width of the accelerometer assembly bracket, so that the slot surface can closely fit the outer frame of the accelerometer assembly bracket, the first bracket slot 6-1 and the second bracket slot 6 The parallelism error between the side surface of -2 and the inner surface of the reference boss 3 is less than 0.01mm.

Preferably, the height of the reference boss 3 is not less than the width of the installation reference surface of the outer bracket of the inertial measurement unit, so that the installation reference surface can be completely attached to the inner surface of the reference boss. As shown in FIG. 4 , during installation, the installation datum is obtained by attaching the datum boss 3 to the datum surface on the frame of the outer bracket of the inertial measurement unit.

Preferably, the width of the base 2 is not less than the distance between the mounting holes on the two sides of the outer frame of the inertial measurement unit, and the thickness is not less than the diameters of the first screw rod 4-1 and the second screw rod 4-2.

Aiming at the problem that the integrated IMU product has a large installation error due to the lack of installation reference in the installation process of the added component and the installation error calibration consistency is poor in the disassembly and maintenance process, based on the above-mentioned device, the present invention also provides a A method for installing an accelerometer assembly in an inertial measurement unit, the method comprising the steps of:

S1. Fit the inner surface of the reference boss 3 with the reference surface on the frame of the outer frame of the inertial measurement unit, and at the same time, fit the lower surface of the device base 2 with the upper surface of the frame of the outer frame of the inertial measurement unit, and make the installation of the two corresponding positions Align the holes, and use screws to fix the base of the device on the frame of the outer bracket;

S2. Define the inner surface of the base 2 as the zero scale reference plane. In the initial state, adjust the zero scale lines of the first measuring ruler 5-1 and the second measuring ruler 5-2 to be aligned with the zero scale reference plane, and use screws to The first mounting support 1-1 and the second mounting support 1-2 of the accelerometer assembly are respectively installed on the first measuring ruler 5-1 and the second measuring ruler 5-2 but not fastened.

S3. Simultaneously adjust the first screw rod 4-1 and the second screw rod 4-2 so that the first bracket slot 6-1 and the second bracket slot 6-2 are closest to the reference plane on the frame of the outer bracket of the inertial measurement unit The frame of the accelerometer assembly bracket is in contact, and when the screw rod is rotated, the scales of the first measuring ruler 5-1 and the second measuring ruler 5-2 relative to the zero scale reference plane are the same, ensuring that the first installation support 1-1 and the second installation support 1-2 have the same amount of precession, ensure that the provided accelerometer installation datum plane is parallel to the installation datum plane of the outer bracket, determine the positions of the first installation support 1-1 and the second installation support 1-2, and fasten them , and then tighten the first screw rod 4-1 and the second screw rod 4-2 with nuts;

S4. Adjust the bracket of the acceleration component so that the upper surface fits the top surface of the first bracket slot 6-1 and the second bracket slot 6-2, and the outer surface fits with the first bracket slot 6-1 and the second bracket slot The side fitting of the groove 6-2, based on this, the determination of the position of the accelerometer assembly is completed, and then the accelerometer assembly is fastened;

S5. After the accelerometer assembly is installed, the installation device is removed from the outer bracket.

If it cannot be installed in place at one time, step S3 and step S4 can be repeated to iteratively complete the installation of the acceleration component.

As shown in Figure 5, it shows the positional relationship between the first mounting support 1-1 and the second mounting support 1-2 and the accelerometer assembly to be installed, by inserting the first bracket slot 6-1 and the second bracket slot 6 -2 The method of attaching the upper surface and the outer surface of the frame of the accelerometer assembly bracket respectively provides an installation reference for the accelerometer assembly.

When the accelerometer assembly is installed on the outer support of the inertial measurement unit, the accelerometer assembly does not have a reference surface, but the outer support has an installation reference. When assembling, the present invention utilizes the reference boss in the device to obtain the installation reference of the outer support , and then provide the mounting reference surface for the accelerometer component bracket through the bracket slot on the mounting boss of the accelerometer component to ensure its installation orientation. By adjusting the screw rod and the measuring ruler, the positions of the mounting bosses of the two accelerometer components can be adjusted. After iterations, the installation error calibration results meet the index requirements. At the same time, adjusting the position of the mounting bosses can realize that the mounting device can be adapted to various types of IMUs. The product structure has strong operability and versatility. This method can effectively improve the installation accuracy of the accelerometer components, and is easy to meet the installation error requirements for IMU products, and the above-mentioned installation method is conducive to obtaining installation error calibration results with good consistency when the product needs to be disassembled and assembled many times. It is convenient for product rework and repair.

The content not described in detail in the present invention is well known to those skilled in the art.

Claims (6)

1. A mounting device for an accelerometer assembly in an inertial measurement unit, characterized in that it comprises a first mounting support (1-1), a second mounting support (1-2), a base (2), a reference boss (3) , the first screw rod (4-1), the second screw rod (4-2), the first measuring ruler (5-1), the second measuring ruler (5-2); The base (2) is a cuboid box, the plane formed by length and width is recorded as the upper surface and the lower surface, the plane formed by width and height is recorded as the left side and the right side, and the plane formed by length and height is recorded as the inner surface and the outer surface; the first measuring ruler (5-1) is coaxially fixedly connected with the first screw rod (4-1) to form the first adjusting rod; the second measuring ruler (5-2) is connected with the second screw rod (4 -2) The coaxial fixed connection constitutes the second adjustment rod; the first adjustment rod is parallel to the second adjustment rod, passing through the middle of the base (2), the first measuring ruler (5-1) and the second measuring ruler (5-1) - the end of the base (2) exposes the inner side of the base (2); the first screw rod (4-1) and the second screw rod (4-2) expose the outer side of the base (2); The lower bottom surface of the base (2) is fixedly connected with the reference boss (3), which is an integrated structure. The inner surface of the reference boss (3) is perpendicular to the lower bottom surface of the base, and is used to stick to the reference surface of the outer bracket of the inertial measurement unit. The upper surface and the lower surface of the base (2) are provided with mounting holes that match the mounting holes on the frame of the outer frame of the inertial measurement unit, and are used to fasten the base (2) on the outer bracket of the inertial measurement unit. By adjusting the first screw The distance between the rod (4-1) and the second screw rod (4-2) relative to the outer surface of the base (2) can be adjusted relative to the first measuring ruler (5-1) and the second measuring ruler (5-2). The distance from the inner surface of the base (2); One end of the first installation support (1-1) is fixedly connected to the first measuring ruler (5-1) by screws, and the other end is engraved with an L-shaped notch, which is recorded as the first bracket slot (6-1); the second installation One end of the support (1-2) is fixedly connected to the second measuring ruler (5-2) by screws, and the other end is engraved with an L-shaped notch, which is recorded as the second bracket slot (6-2); the first bracket slot (6 -1) and the second bracket slot (6-2) are used to provide a reference for the installation of the accelerometer assembly. 2. The installation device of accelerometer assembly in a kind of inertial measurement unit according to claim 1, it is characterized in that the first screw rod (4-1) and the second screw rod (4-2) are mounted on the base by nuts (2) The outer surface is fastened to the base (2). 3. The installation device of an accelerometer assembly in an inertial measurement unit according to claim 1, characterized in that: the first bracket slot (6-1) and the second bracket slot (6-2) The top surface of the L-shaped notch is parallel to the upper surface and the lower surface of the base (2), the side surface is parallel to the inner surface of the reference boss (3), and the depth of the top surface along the length direction of the base (2) is not less than the frame of the accelerometer assembly bracket The width is such that the surface of the card slot can be closely attached to the upper surface of the outer frame of the accelerometer assembly bracket, and the sides of the first bracket slot (6-1) and the second bracket slot (6-2) are in contact with the reference boss (3) The parallelism error of the inner surface is less than 0.01mm. 4. The installation device of the accelerometer assembly in a kind of inertial measurement unit according to claim 1, it is characterized in that: the height of the described reference boss (3) is not less than the width of the installation reference surface of the outer bracket of the inertial measurement unit, which can make The installation reference surface is all attached to the inner surface of the reference boss. 5. The mounting device for the accelerometer assembly in an inertial measurement unit according to claim 1, wherein the width of the base (2) is not less than the distance between the mounting holes on the two sides of the outer frame of the inertial measurement unit, The thickness is not smaller than the diameters of the first screw rod (4-1) and the second screw rod (4-2). 6. A method for installing an accelerometer assembly in an inertial measurement unit, characterized in that it comprises the steps: S1. Fit the inner surface of the reference boss (3) with the reference plane on the frame of the outer frame of the inertial measurement unit, and at the same time, attach the lower surface of the device base (2) to the upper surface of the frame of the outer frame of the inertial measurement unit, and make the two Align the mounting holes at the corresponding positions, and use screws to fix the device base (2) on the frame of the outer bracket; S2. Define the inner surface of the base (2) as the zero scale reference plane. In the initial state, adjust the zero scale line of the first measuring ruler (5-1) and the second measuring ruler (5-2) to be consistent with the zero scale reference plane. Alignment, use screws to install the first mounting support (1-1) and the second mounting support (1-2) of the accelerometer assembly on the first measuring ruler (5-1) and the second measuring ruler (5-2) respectively up but not fastened; S3. Simultaneously adjust the first screw rod (4-1) and the second screw rod (4-2) so that the first bracket slot (6-1) and the second bracket slot (6-2) are in line with the distance inertial measurement unit The datum plane on the frame of the outer support is in contact with the frame of the accelerometer assembly bracket closest to it, and when the screw rod is turned, the scales of the first measuring ruler (5-1) and the second measuring ruler (5-2) relative to the zero-scale datum plane are the same, ensuring The first installation support (1-1) and the second installation support (1-2) have the same amount of precession, to ensure that the provided accelerometer installation reference plane is parallel to the installation reference plane of the outer support, determine the first installation support (1 -1) and the position of the second installation support (1-2), tighten it, and then use the nut to connect the first screw rod (4-1) and the second screw rod (4-2) from the outer side of the base (2) ) is fastened; S4. Adjust the bracket of the acceleration component so that the upper surface of the frame fits the top surface of the first bracket slot (6-1) and the top surface of the second bracket slot (6-2), and the outer surface fits with the first bracket slot (6-2). 1) Fitting with the side of the second bracket slot (6-2), based on this, the position of the accelerometer assembly is determined, and then the accelerometer assembly is fastened; S5. After the accelerometer assembly is installed, the installation device is removed from the outer bracket.

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