Inertial measurement unit centroid measurement tool
The inertial measurement unit's center of mass measurement tool, based on the principle of gravitational torque balance, solves the accuracy problem of inertial measurement unit center of mass position measurement, realizing convenient and reliable center of mass measurement, and is suitable for center of mass measurement of inertial measurement units.
Patent Information
- Application Number
- CN202521935567.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-09
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2035-09-09
AI Technical Summary
In existing technologies, the inertial measurement unit (IMU) is prone to angular vibration and signal noise in vibration environments because the center of mass does not coincide with the center of elastic support, making it difficult to accurately measure the position of the IMU's center of mass. Existing instruments are difficult to apply to the measurement of the center of mass position of the IMU.
An inertial measurement system based on the principle of gravitational torque balance is used to measure the center of mass. The system combines a frame, support, level, ruler, vernier, and weights, and uses the torque balance formula to calculate the position of the center of mass, ensuring a convenient and accurate measurement process.
It achieves accuracy and reliability in inertial navigation system (INS) center of mass measurement, the measurement process is simple, the measurement results are consistent with the actual installation state of the INS, the signal noise caused by angular vibration is reduced, and the reliability of the INS is improved.
Smart Images
Figure CN224681730U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the measurement of the center of mass of a product, specifically to an inertial measurement unit combined with a center of mass measurement tool, belonging to the field of inertial measurement technology. Background Technology
[0002] In an online vibration environment, the inertial measurement unit (INS) experiences angular vibration due to the misalignment of its center of mass with the center of its elastic support. This angular vibration is sensitive to the gyroscopes within the INS, increasing the noise in the INS' angular velocity output signal. In severe cases, this can even render the INS' output signal unusable; this phenomenon is known as line-angle coupling. Reducing the difference between the INS's center of mass and the center of its elastic support is one measure to suppress line-angle coupling. Therefore, it is necessary to measure the position of the INS' center of mass during the INS' development and production process. Currently, the position of the INS' center of mass is generally estimated using CAD software during structural design, which results in a discrepancy between the actual and theoretical center of mass positions. Other center of mass measurement instruments are generally designed for different products (with significant differences in mass and shape compared to INS units) and are difficult to apply to measuring the center of mass of INS units. Utility Model Content
[0003] To address the aforementioned shortcomings of existing technologies, the purpose of this utility model is to provide an inertial measurement combination centroid measurement tool. This utility model provides accurate and reliable centroid measurement results and a convenient measurement process.
[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows: An inertial measurement unit (IMU) centroid measuring tool includes a frame and two opposing supports. The frame is rectangular, and its outer side is rotatably mounted on the upper ends of the two supports via a pivot. The pivot is parallel to two side frames of the frame and connects to the midpoint of the other two side frames along their length. The frame has a mounting structure for fixing the IMU to be measured within the frame. One side of the frame connected to the pivot has a level, aligned with the length of the side frame and with its midpoint located in the middle. The other side has a scale, aligned with the length of the side frame and with its center located in the middle of the side frame. The scale has graduation lines. A vernier is mounted on the scale, sliding along its length. A weight is suspended from the center of the vernier by a rope. Moving the vernier moves the weight, thus balancing the IMU to be measured and ensuring the level is horizontal.
[0005] Furthermore, it also includes a horizontally arranged base, the two supports being parallel vertically arranged isosceles triangular plates, the base of which is fixedly installed on the base, and the two sides of the frame are rotatably connected to the vertices of the two isosceles triangular plates through two half-axises respectively.
[0006] Furthermore, a counterweight is provided below the frame when it is in a horizontal position. By adjusting the position of the counterweight, the center of mass of the whole consisting of the frame and the counterweight is located directly below the axis of rotation.
[0007] Furthermore, a groove along the length direction is provided on the scale, the groove runs through the upper and lower surfaces of the scale, a slider is provided at the center below the vernier, the slider is located in the groove and can slide along the groove together with the vernier, one end of the suspension rope is connected to the slider, and the other end of the suspension rope passes downward through the groove and is connected to the weight.
[0008] Furthermore, the mounting structure consists of four threaded holes on the frame, located at the center of each of the four side edges of the frame. The frame is fixedly connected to the inertial measurement unit to be measured via these threaded holes.
[0009] Furthermore, the vernier has a marker line at its center, and the position of the scale line corresponding to the marker line represents the scale at which the vernier is located.
[0010] Compared with the prior art, the present invention has the following beneficial effects: 1. This utility model is based on the principle of gravitational torque balance for measurement. The principle is simple and easy to understand. The pivot between the support and the frame forms the fulcrum of the torque. The vernier and weights, as a whole, constitute one end of the torque, while the inertial navigation system (including the vibration damper) at the center of mass to be measured constitutes the other end. The frame, scale, level, and counterweight are all centrally mounted and are in a self-balancing state, thus not affecting the measurement of the inertial navigation system's center of mass. Therefore, by simply moving the vernier and weights to balance the two ends of the torque, the position of the center of mass can be calculated using the torque balance formula. This utility model provides accurate and reliable center of mass measurement results, and the measurement process is convenient.
[0011] 2. During the measurement process, the counterweight helps to achieve and maintain a stable balance more quickly, making it easier to read the position indicated by the vernier.
[0012] 3. Since the inertial navigation system (INS) is actually installed on the support center through a vibration damper during installation, this utility model directly installs the INS and the vibration damper as a whole (or the vibration damper can be understood as a component of the INS) on the frame when measuring the center of mass. This not only facilitates the installation of the INS within the frame, but also ensures that the measured center of mass position is more in line with the actual working requirements of the INS center of mass. Attached Figure Description
[0013] Figure 1 This is a schematic diagram of the centroid measuring tool of the inertial measurement assembly of this utility model.
[0014] Figure 2 This is a schematic diagram illustrating the definition of the inertial navigation system coordinate system of this utility model.
[0015] Figure 3This is a schematic diagram of the X-coordinate of the centroid measured by this utility model.
[0016] Figure 4 This is a schematic diagram of the Y-coordinate for measuring the centroid of this utility model.
[0017] Figure 5 This is a schematic diagram of the Z-coordinate of the centroid measured by this utility model.
[0018] Among them, support ;frame ; scale ;cursor Weights Level Counterweight Inertial navigation system Vibration damper Half shaft . Detailed Implementation
[0019] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0020] See Figure 1 As shown in the figure, the inertial measurement unit (IMU) centroid measuring tool of this invention includes a frame ② and two opposing supports ①. The frame ② is a rectangular structure, and its outer side is rotatably mounted on the upper end of the two supports ① via a pivot ⑩. The pivot ⑩ is parallel to the two side edges of the frame and connects to the midpoint of the length direction of the other two side edges. The frame has a mounting structure for fixing the IMU to be measured (INS) inside the frame ②. On one of the two side edges of the frame connected to the pivot, a level ⑥ (bubble level) is provided. The level ⑥ is aligned with the length direction of the side edge, and its midpoint is located in the middle of the side edge. On the other side, a scale ③ is provided. The scale ③ is aligned with the length direction of the side edge, and its center is located in the middle of the side edge. The scale has graduation lines. A vernier ④ that can slide along the length of the scale ③ is provided on the scale ③. A weight ⑤ is suspended from the center of the vernier ④ by a rope. By moving the vernier, the weight is moved, thereby balancing the inertial measurement combination to be measured so that the level is in a horizontal state.
[0021] This invention is based on the principle of gravitational torque balance for measurement. The principle is simple and easy to understand. The pivot between the support and the frame forms the fulcrum of the torque. The vernier and weights form one end of the torque as a whole, and the inertial system at the position of the center of mass to be measured forms the other end of the torque. The frame, scale, and level are all centrally mounted and are self-balancing, so they do not affect the balance of the measured torque. Thus, by simply moving the vernier and weights to balance the two ends of the torque, the position of the center of mass can be calculated using the torque balance formula.
[0022] Furthermore, this measuring tool also includes a horizontally positioned base, with two parallel vertically arranged isosceles triangular plates. The base of the isosceles triangular plates is fixedly mounted on the base, and the two sides of the frame are rotatably connected to the vertices of the two isosceles triangular plates via two half-axises. Connecting the two independent supports into a single unit via the base enhances the overall integrity and stability of the measuring tool, and also facilitates its placement on a measuring platform for measurement.
[0023] Furthermore, a counterweight ⑦ is provided below the frame ② when it is in a horizontal state. By adjusting the position of the counterweight, the center of mass of the unit consisting of the frame and the counterweight is located directly below the axis of rotation. In this embodiment, the counterweight is installed in the middle of the lower surface of one of the frame's side edges connected to the axis of rotation. The counterweight helps the frame to remain stably horizontal when the vernier, weights, and the inertial measurement object to be measured form a gravitational torque balance. Under the action of the counterweight, the equilibrium state can be reached and maintained more quickly, making it easier to read the vernier's indicated position.
[0024] A groove running along the length of the scale extends through both the upper and lower surfaces. A slider is located at the center below the vernier, positioned within the groove and sliding along it together with the vernier. One end of a suspension rope is connected to the slider, while the other end passes downwards through the groove and connects to the weight. This groove and slider design facilitates the installation and sliding of the vernier on the scale, as well as the suspension of the weight.
[0025] The mounting structure consists of four threaded holes on the frame, located at the center of each of the four side edges. The frame is fixedly connected to the inertial measurement unit (IMU) to be measured via these threaded holes. Since a conventional IMU has a rectangular structure and multiple mounting holes, it can be mounted on the frame using these threaded holes. Even if the IMU and vibration damper are fixedly connected as a single unit before being mounted to the frame, the vibration damper also has a mounting structure that matches the threaded holes on the frame. This mounting structure on the frame facilitates adjusting the IMU's mounting position, ensuring that the X, Y, and Z axes are horizontal and perpendicular to the rotation axis.
[0026] The vernier has a marker line at its center, and the position of the scale line corresponding to the marker line represents the scale at which the vernier is located. The vernier is essentially a pointer used to indicate displacement, but because the vernier itself needs to be mounted with weights and has a certain size, it is inconvenient to directly observe the position of the scale line indicated by the vernier. Therefore, by setting a marker line at the center of the vernier, the marker line is equivalent to a pointer and can replace the vernier in indicating the scale line.
[0027] The steps for measuring the centroid of the inertial navigation system according to this invention are as follows: 1) Define the coordinate system OXYZ of the inertial navigation system; the origin O of the coordinate system OXYZ is located at the center of the mounting flange of the inertial navigation system, i.e. the support center, and the X-axis, Y-axis and Z-axis are perpendicular to each other; Figure 2 This is one way of defining the inertial navigation system coordinate system in this embodiment.
[0028] 2) Measure the sum of the masses of the inertial navigation system (⑧) and the damper (⑨) W2, and the sum of the masses of the vernier (④) and the weights (⑤) W1, respectively; 3) Steps for measuring the X-coordinate of the centroid: 3a) Install the inertial navigation system ⑧ together with the vibration damper ⑨ inside the frame ② using the mounting structure; make the X-axis of the inertial navigation system ⑧ horizontal and perpendicular to the rotation axis ⑩ of the frame; 3b) Install the scale ③ together with the vernier ④ on one of the side edges of the frame connected to the pivot; 3c) Install the level ⑥ on the other side of the frame connected to the pivot; 3d) Install the counterweight ⑦ on the frame ② and position the center of gravity of the counterweight ⑦ directly below the line where the pivot ⑩ is located; 3e) Suspend the weight ⑤ on the vernier ④ with a rope, and move the vernier ④ to move the weight ⑤ along the length of the scale ③; 3f) When the level ⑥ is horizontal, read the reading on the scale indicated by the mark line set on the center of the vernier ④, and denote it as A. x ; 3g) Measurement status as follows Figure 3 As shown; The X-coordinate of the centroid (3h) is calculated using equation (1). X = A x ×W1÷W2 - L Equation (1) Where L is the distance from the center plane of the inertial navigation flange to the frame mounting surface; 4) Steps for measuring the Y-coordinate of the centroid: 4a) Install the inertial navigation system (INS) along with the vibration damper inside the frame using the mounting structure; make the Y-axis of the INS horizontal and perpendicular to the rotation axis of the frame; 4b) Mount the scale and vernier together on one of the edges of the frame connected to the pivot; 4c) Mount the level on the other side of the frame that is connected to the pivot; 4d) Install the counterweight ⑦ on the frame ② and position the center of gravity of the counterweight ⑦ directly below the line where the pivot ⑩ is located; 4e) Suspend the weights on the vernier scale by a rope, and move the vernier scale to move the weights along the length of the scale. 4f) When the level is horizontal, read the value on the scale indicated by the mark line set on the vernier center, and denote it as A. y ; 4g) Measurement status as follows Figure 4 As shown; The Y-coordinate of the centroid (4h) is calculated using equation (2). Y = Ay×W1÷W2 Formula (2) 5) Steps for measuring the Z-coordinate of the centroid: 5a) Install the inertial navigation system (INS) along with the vibration damper into the frame using the mounting structure; ensure that the INS Z-axis is horizontal and perpendicular to the frame's axis of rotation; 5b) Mount the scale and vernier together on one of the edges of the frame connected to the pivot; 5c) Mount the level on the other side of the frame that is connected to the pivot; 5d) Install the counterweight ⑦ on the frame ② and position the center of gravity of the counterweight ⑦ directly below the line where the pivot ⑩ is located; 5e) Suspend the weights on the vernier scale by a rope, and move the vernier scale to move the weights along the length of the scale. 5f) When the level is horizontal, read the reading on the scale indicated by the mark line set on the vernier center, and denote it as A. z ; 5g) Measurement status as follows Figure 5 As shown; The Z-coordinate of the centroid (5h) is calculated using equation (3). Z = Az×W1÷W2 Equation (3) Through the above steps, the X, Y, and Z coordinates of the center of mass of the inertial measurement unit in the coordinate system of the elastic support center can be measured.
[0029] In actual measurement, the connection between frame ② and support ① can remain unchanged (at this time, the level ⑥, scale ③, vernier ④, and weights ⑤ do not move). When measuring the coordinates of the inertial navigation system (INS) in another direction, INS ⑧ and vibration damper ⑨ can be removed and reinstalled so that the direction to be measured is horizontal and perpendicular to the axis of rotation ⑩. Alternatively, the frame and INS can remain in their installed state, the level, scale, vernier, and weights can be removed from the frame, and then the frame can be rotated so that the direction to be measured (provided that the plane containing the previous measurement direction is perpendicular to the axis of rotation) is horizontal and perpendicular to the axis of rotation. Then, the level, scale, vernier, and weights can be reinstalled on the frame for measurement.
[0030] The above embodiments of this utility model are merely illustrative examples and are not intended to limit the implementation of this utility model. Those skilled in the art can make other variations and modifications based on the above description. It is impossible to exhaustively list all possible implementations here. All obvious variations or modifications derived from the technical solutions of this utility model are still within the protection scope of this utility model.
Claims
1. An inertial measurement unit with a centroid measuring tool, characterized in that: The device includes a frame and two opposing supports. The frame is rectangular, and its outer side is rotatably mounted on the upper ends of the two supports via a pivot. The pivot is parallel to two side frames of the frame and connects to the midpoint of the other two side frames along their length. The frame has a mounting structure for fixing the inertial measurement assembly to be measured within the frame. One side of the frame connected to the pivot has a level, aligned with the length of the side frame and with its midpoint located in the middle. The other side has a scale, aligned with the length of the side frame and with its center located in the middle of the side frame. The scale has graduation lines. A vernier is mounted on the scale, sliding along its length. A weight is suspended from the center of the vernier by a rope. Moving the vernier moves the weight, thus balancing the inertial measurement assembly to be measured and keeping the level horizontal.
2. The inertial measurement unit centroid measurement tool according to claim 1, characterized in that: It also includes a horizontally set base, the two supports being parallel and vertically set isosceles triangular plates, the base of which is fixedly mounted on the base, and the two sides of the frame are rotatably connected to the vertices of the two isosceles triangular plates through two half-axises.
3. The inertial measurement unit centroid measurement tool according to claim 1, characterized in that: A counterweight is placed below the frame when it is in a horizontal position. By adjusting the position of the counterweight, the center of mass of the whole consisting of the frame and the counterweight is located directly below the axis of rotation.
4. The inertial measurement unit centroid measurement tool according to claim 1, characterized in that: A groove along the length of the scale is provided, which runs through the upper and lower surfaces of the scale. A slider is located at the center below the vernier, and the slider is located in the groove and can slide along the groove together with the vernier. One end of the suspension rope is connected to the slider, and the other end of the suspension rope passes downward through the groove and is connected to the weight.
5. The inertial measurement unit centroid measuring tool according to claim 1, characterized in that: The mounting structure consists of four threaded holes on the frame, located at the center of each of the four side edges of the frame. The frame is fixedly connected to the inertial measurement unit to be measured via these threaded holes.
6. The inertial measurement unit centroid measurement tool according to claim 1, characterized in that: The vernier has a marker line at its center, and the position of the scale line corresponding to the marker line represents the scale at which the vernier is located.