CN111811504A - Stacked micro-inertial measurement unit under high overload and high dynamic application environment - Google Patents

Abstract

The invention discloses a stacked micro-inertial measurement unit under a large overload and high dynamic application environment, comprising at least two circuit boards, at least one inertial sensor is arranged on the circuit boards, and the circuit boards are stacked by an elastic support structure. The layers are fixed, the elastic support structure includes a fixed part and an elastic part, the elastic part is made of elastic material, and the circuit boards are electrically interconnected through a flexible conductive tape connector, and the flexible conductive tape connector includes a flexible conductive tape connector. The length of the flexible conductive tape is greater than the spacing between the circuit boards. The micro-inertial measurement unit adopts a laminated design, and all inertial sensors are installed on a plane, which improves the system's ability to resist large overloads. The electronic components inside the system are laminated with specially designed elastomer support materials to realize micro-inertial measurement. The mechanical protection of the unit in the high overload and high dynamic environment.

Description

Stacked micro-inertial measurement unit under high overload and high dynamic application environment

technical field

The invention relates to the technical field of structure and mechanical protection design of a micro-inertial measurement unit, in particular to a stacked micro-inertial measurement unit under a large overload and high dynamic application environment.

Background technique

With the development of semiconductor technology, MEMS (Micro-Electro-Mechanical System) technology is widely used in military fields such as drones, guided munitions, and stable platforms due to its miniaturization, low cost, and high reliability. The micro-inertial measurement unit based on MEMS technology, as a sensor system for measuring the dynamic data of the carrier, has the advantages of high accuracy, small size, strong environmental adaptability, and low cost, and can be used in harsh environments such as large overload and high dynamics. The micro-inertial measurement unit performs motion perception through the internal integrated MEMS inertial sensor. The measurement principle is: the movement and relative displacement of the silicon micro-mechanical structure inside the sensor generate electrical signals that can be detected, and the special integrated circuit processes the electrical signals and outputs them externally. Analog or digital, so as to perceive the motion information of the carrier.

As a detection device for the motion state of the carrier, the micro-inertial measurement unit needs to meet the requirements of six-degree-of-freedom inertial parameter measurement. Usually, the orthogonal assembly of inertial sensors is used to realize the six-degree-of-freedom measurement of its sensitive axial direction. Due to the design principle of the silicon micro-mechanical structure of the MEMS inertial sensor, the ability to withstand overload shock is weak in the case of lateral and vertical installation. And in the large overload and high dynamic environment, the micro-inertial measurement measurement unit will bear great transmission stress and high-frequency vibration, which will affect the system function or even fail. Therefore, for the reliability in harsh application environments, it is necessary to optimize the system scheme of the micro-inertial measurement unit and design the environmental protection. And in order to reduce errors in machining and assembly, and at the same time ensure system reliability and coordination strength, the micro-inertial measurement unit tries to avoid the splicing and assembly design of multiple parts. Some of the existing practices and their shortcomings are as follows:

The invention patent "Inertial Measurement Unit and the Movable Device Using the Inertial Measurement Unit" with the publication number CN 110017835 A proposes an inertial measurement unit with a constant temperature heating function and a movable device using the inertial measurement unit. The inertial measurement unit adopts a frame structure with high thermal conductivity, and uses the heating source to generate heat to heat the circuit board embedded in the frame. The real-time temperature of the system is sensed through multi-sensors, and the internal heat insulation board and rubber sleeve maintain the preset temperature of the system. Through the special structure and heat conduction path design, this solution ensures that the system is in a constant temperature state during operation, reduces the temperature drift of the system, and improves the performance of the system. The design is mainly designed to optimize the system environment according to the temperature characteristics of the inertial measurement unit, and does not provide special protection for the large overload and high dynamic application environment.

The invention patent "Modular and Scalable MEMS Inertial Measurement Unit" with the publication number CN 105352501 A proposes a scalable MEMS inertial measurement unit with an orthogonal assembly of sensitive modules and a cube frame, and an internal stack of computer modules. In this scheme, four sensitive modules are vertically assembled with the four side frames of the square bracket by screws, and two sensitive modules and the computer module are horizontally assembled inside the square bracket, and are interconnected and supported by single-headed studs. The inertial measurement unit has a compact interior, a high degree of modularity and flexibility, and good system configurability. However, since three modules are stacked inside the cube bracket, the internal space is very limited, and the sensitive modules are installed vertically and horizontally, so the signal connection between the sensitive module and the computer module will increase the assembly complexity of the inertial measurement unit.

The invention patent "a new type of micro-inertial measurement unit" with the publication number CN 104296746 A proposes a micro-inertial measurement unit combination that can be assembled by welding a MEMS accelerometer, a MEMS gyroscope and a mounting base on the same plane or parallel stacking. The invention selects MEMS accelerometers and MEMS gyroscopes with different sensitive structures, so that the inertial measurement axis is horizontal or vertical to the welding plane of the sensor, so as to meet the inertial parameter measurement requirements of six degrees of freedom. This solution avoids the orthogonal assembly of inertial sensors, has large space utilization, high system integration, and strong anti-overload capability. However, it does not provide special protection for large overload and high dynamic application environments.

The invention patent of the publication number CN 107966144 A, "An Assembly Structure of Inertial Measurement Combination Based on MEMS Sensors", proposes an assembly structure scheme for realizing three-axis orthogonal installation of MEMS inertial sensors through a mounting base. The structure of the installation base is approximately hexahedron, the MEMS sensor is installed on the top surface and the side surface, and the gyro signal processing circuit is installed on the bottom surface. The installation base has reserved wiring grooves, and the signal wires are bound to form a wire bundle and lead out to the outside. In this scheme, the signal conversion circuit is placed in a closed cavity at the bottom of the base to achieve physical isolation and reduce signal interference. However, the structure of the assembly is relatively complex, the processing is difficult, and the internal signal transmission adopts the wire method, which increases the assembly process.

The invention patent of Announcement No. CN 105922836 A "Anti-Shock Micro Inertial Measurement Unit with Adjustable Damping" proposes a micro-inertial measurement unit composed of an outer casing, an inertial assembly, a shock absorber and a sealing gasket. The outer casing and the gasket form a closed space, the inertial assembly is suspended in the closed casing through the shock absorber, and the inner air is a high-damping elastic body. The inner surface of the lower casing is provided with a convex stop structure, which can adjust the impact resistance of the system. The shock absorber contains vibration-damping rubber with uniform grooves on the upper and lower surfaces to control the shock's resonance frequency. The impact resistance and vibration reduction performance of this solution can be adjusted according to the application environment, with high flexibility, and various damping designs are conducive to vibration isolation. However, there is a certain angle between the sensitive axial direction of the inertial device and the axial direction of the micro inertial measurement unit in this scheme, and the scale adjustment needs to be carried out through system compensation, which increases the system error.

SUMMARY OF THE INVENTION

In view of the above-mentioned technical problems, the purpose of the present invention is to provide a stacked micro-inertial measurement unit under a high-overload and high-dynamic application environment. In order to improve the system's ability to resist large overload, the internal electronic components of the system are laminated with specially designed elastomer supporting materials, which realizes the mechanical protection of the micro-inertial measurement unit in the large overload and high dynamic environment.

The technical scheme of the present invention is:

A stacked micro-inertial measurement unit under a large overload and high dynamic application environment includes at least two circuit boards, at least one inertial sensor is arranged on the circuit boards, and the circuit boards are laminated and fixed by an elastic support structure, so the The elastic support structure includes a fixed part and an elastic part, the elastic part is made of elastic material, and the circuit boards are electrically interconnected through a flexible conductive tape connector, the flexible conductive tape connector includes a flexible conductive tape, the The length of the flexible conductive tape is greater than the spacing between the circuit boards.

In a preferred technical solution, the material parameters of the elastic material are designed according to the application environment, so as to ensure that the deformation of the elastic part is in the elastic range in the stage of bearing a large overload.

In a preferred technical solution, the damping characteristic of the elastic material and the natural frequency of the system are calculated, so that the damping characteristic of the elastic material is inconsistent with the natural frequency of the system.

In a preferred technical solution, the fixing portion is connected to the elastic portion through a mosaic structure, and is fixedly connected by adhesive.

In a preferred technical solution, the elastic support structure is a circular truncated structure, and the fixing portion is provided with threads.

In a preferred technical solution, the flexible conductive strip connector further includes a gold finger pad structure and a plastic body structure, and two ends of the flexible conductive strip lead out internal wiring copper foils, which are thickened to form gold finger welding with a certain strength plate, and injection molding the gold finger pad and part of the flexible conductive tape to obtain a plastic body structure.

In a preferred technical solution, the control circuit board is connected to the electrical structural connector through a flexible conductive tape connector.

In a preferred technical solution, a metal casing is provided on the periphery of the stacked micro-inertial measurement unit, and the metal casing includes a square sleeve and a plane base, and each side of the square sleeve and the plane base has a mounting flange.

Compared with the prior art, the advantages of the present invention are:

1. The internal electronic components of the system of the present invention are laminated and assembled with specially designed elastomer supporting materials, which realizes the mechanical protection of the micro-inertial measurement unit under the large overload and high dynamic environment, and the information is transmitted between the circuit boards through the flexible conduction belt. The interconnection ensures the reliability of the electrical interface. At the same time, the layered structure and the information interconnection method make the function of the micro-inertial measurement unit flexible and expandable.

2. The micro-inertial measurement unit adopts a stacked design, and all inertial sensors are installed on a plane, so that when the micro-inertial measurement unit is subjected to a large overload, the motion direction of the silicon micro-sensitive structure of the inertial sensor does not coincide with the overload direction, which improves the performance. The system has the ability to resist large overload. The circuit board support structure adopts a certain strength of elastomer material, so that it can relieve large overload shock and high-frequency vibration through deformation, and the mechanical connection between the circuit boards adopts the same method, which can attenuate the transmission of overload and vibration. The material characteristics of the elastic support structure are designed so that the material is in the elastic deformation range during the process of bearing a large overload, so that the sensor circuit board of the micro-inertial measurement unit can return to the initial position after the large overload shock stage is over. Since the support structure is made of elastic material, the external vibration is transmitted to the interior of the micro-inertial measurement unit structure, and the circuit board will compress or stretch the elastic support structure due to its own inertia, reducing the displacement caused by vibration and attenuating vibration. This situation will cause the spacing between the circuit boards to change to a certain extent. The electrical interconnection method of the circuit board using the traditional wiring harness will cause the wiring harness to move and impact between the circuit boards, which will produce great noise on the output signal and affect the system function; the use of connectors In the way of interconnection, vibration will affect the strength and reliability of the interconnection between the circuit boards. The invention adopts the electrical interconnection method of the flexible conductive tape, and the length of the conductive tape is slightly longer than the spacing between the circuit boards, so that the electrical interconnection remains firm and reliable when the spacing between the circuit boards is compressed or stretched.

Description of drawings

Below in conjunction with accompanying drawing and embodiment, the present invention is further described:

Fig. 1 is the micro-inertial measurement unit schematic diagram of the present invention;

Fig. 2 is the micro-inertial measurement unit system schematic diagram of the present invention;

FIG. 3 is a schematic diagram of the stacked design of the micro-inertial measurement unit of the present invention;

FIG. 4 is a schematic diagram of the design of an elastic support structure according to an embodiment of the present invention;

Fig. 5 is the connection structure schematic diagram of Fig. 4;

6 is a schematic diagram of the design of an elastic support structure according to another embodiment of the present invention;

Fig. 7 is the connection structure schematic diagram of Fig. 6;

8 is a schematic diagram of the overall structure of the flexible conductive tape connector of the present invention;

FIG. 9 is a schematic structural diagram of the flexible conductive belt connector of the present invention after the injection molding is removed.

1: Square sleeve, 2: Flat base, 3: Circuit board locking member, 41: Upper elastic support structure, 411: Upper metal external thread structure, 412: Elastic damping material structure, 413: Bottom metal external thread structure, 42 : Middle elastic support structure, 421: Upper metal inner thread structure, 422: Elastic damping material structure, 423: Lower metal outer thread structure, 43: Lower elastic support structure, 431: Upper metal inner thread structure, 432: Elastic damping material structure , 433: Bottom metal external thread structure, 5: Accelerometer circuit board, 51: X-axis accelerometer, 52: Y-axis accelerometer, 53: Z-axis accelerometer, 6: Gyroscope circuit board, 61: X-axis gyroscope , 62: Y-axis gyroscope, 63: Z-axis gyroscope, 7: Control circuit board, 71: Control chip, 8: Flexible conductor tape connector, 801: Gold finger pad, 802: Plastic structure, 803: Flexible conductor Belt, 9: Electrical structure connector, 10: Groove, 11: Through hole, 12: Bump, 13: Extension.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the specific embodiments and the accompanying drawings. It should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. Also, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concepts of the present invention.

As shown in FIG. 1 , in the stacked micro-inertial measurement unit designed by the present invention, the outer metal shell is made of high-strength super-hard aluminum, which is matched in the form of a square sleeve 1 and a plane base 2 . The square sleeve 1 and the plane base 2 have mounting flanges on each side, and are respectively provided with threaded holes and round through holes according to the assembly structure, so as to realize the system assembly of the micro-inertial measurement unit and the positioning and installation on the carrier mounting plane.

A stacked micro-inertial measurement unit under a large overload and high dynamic application environment includes at least two circuit boards, at least one inertial sensor is arranged on the circuit boards, and the circuit boards are laminated and fixed by an elastic support structure, and the elastic support structure includes a fixing part and a The elastic part is made of elastic material, and the circuit boards are electrically interconnected through a flexible conductive strip connector, and the flexible conductive strip connector includes a flexible conductive strip, and the length of the flexible conductive strip is greater than the distance between the circuit boards.

As shown in FIGS. 2 and 3 , this embodiment is described by taking three circuit boards as an example, including a control circuit board 7 , an accelerometer circuit board 5 and a gyroscope circuit board 6 . The control circuit board 7 is provided with a control chip 71, the accelerometer circuit board 5 is provided with an X-axis accelerometer 51, a Y-axis accelerometer 52, a Z-axis accelerometer 53, and the gyroscope circuit board 6 is provided with an X-axis gyroscope 61 , Y-axis gyroscope 62, Z-axis gyroscope 63.

The lower elastic support structure 43 is fixed inside the plane base 2 through threaded holes. The lower elastic support structure 43 includes an upper end metal inner thread structure 431, an elastic damping material structure 432, and a lower end metal outer thread structure 433. The lower elastic support structure 43 is approximately a two-layer circular truncated structure Structure, as shown in Figures 6 and 7, the lower round table is made of metal material and is provided with an external thread, which is locked with the plane base 2; the upper round table is made of elastic material and the top surface is provided with a metal structure inner thread, and the middle elastic support structure 42 to cooperate to fix the control circuit board 7 . The upper metal inner thread structure 431 and the lower metal outer thread structure 433 are connected to the elastic damping material structure 432 through a mosaic structure. As shown in FIG. 7, they are fixed by glue. The mosaic structure design increases the bonding surface and enables assembly. Strong and improved reliability.

The middle elastic support structure 42 is the same as the lower elastic support structure 43, as shown in Figures 6 and 7, including the upper end metal internal thread structure 421, the elastic damping material structure 422, the lower end metal external thread structure 423, the middle elastic support structure 42 and the upper elastic support structure 421. The support structure 41 cooperates to fix the gyroscope circuit board 6. The upper elastic support structure 41 includes an upper metal external thread structure 411, an elastic damping material structure 412, and a lower metal external thread structure 413. As shown in Figures 4 and 5, the upper elastic support The structure 41 and the circuit board locking member 3 fix the accelerometer circuit board 5 . The upper metal external thread structure 411 and the lower metal external thread structure 413 are connected to the elastic damping material structure 412 through a mosaic structure, and then fixedly connected by glue.

A preferred embodiment of the mosaic structure, as shown in FIG. 5 , the elastic damping material structure 412 is a circular truncated structure, with grooves 10 at both ends, a through hole 11 in the middle, a metal external thread structure 411 at the upper end and a lower end The middle part of the metal external thread structure 413 is provided with a protrusion 12 which cooperates with the through hole 11 , and the edge is provided with an extension part 13 extending downward, and the extension part 13 is snap-fitted with the groove 10 .

The elastic damping material structure is made of elastic material, such as hard silicone rubber or polyurethane material. Due to the wide range of related material parameters of hard silicone rubber or polyurethane material and the different characteristics of different components, detailed parameters are not listed here. According to the application environment of the micro-inertial measurement unit, the elastic material design its material parameters to ensure that the deformation of the support structure is in the elastic range when it is subjected to a large overload stage. At the same time, considering its damping characteristics and the natural frequency of the system, it can attenuate the high-frequency vibration introduced from the outside world under the working state, and avoid the resonant frequency of the carrier system to improve the reliability of the micro-inertial measurement unit.

Flexible conductive tape connectors 8 are designed between circuit boards to realize signal interconnection between circuit boards. As shown in Figures 8 and 9, the flexible conductor tape connector 8 adopts a plastic body structure with gold finger pads, and a flexible conductor tape of polyimide (PI) or other high-reliability substrates is used in the middle. The connector 8 includes gold finger pads 801 , a plastic structure 802 , and a flexible conductive strip 803 . The two ends of the flexible conductive tape 803 lead out the internal wiring copper foil, and the gold finger pads 801 with a certain strength are formed by thickening, and the gold finger pads 801 and part of the flexible conductive tape 803 are injection-molded with a specially designed mold to establish a plastic body structure. 802, so as to realize the flexible conductive tape connector 8 for electrical interconnection. The electrical interface of the micro-inertial measurement unit is also connected by a flexible conductive tape, which is led out from the control circuit board 7 and connected to the electrical structure connector 9 through the flexible conductive tape connector 8 . The accelerometer circuit board 5 of the micro-inertial measurement unit has the same structure as the gyroscope circuit board 6, the relative position of the signal interface in the circuit board is the same, and the communication method is the same, such as SPI, IIC, etc., to achieve the same position with the control circuit board 7 Connect and assemble on demand. If the functional requirement of the system is a six-axis micro-inertial measurement unit, the standard structure shall be followed: the control circuit-gyroscope circuit-accelerometer circuit is assembled from bottom to top to realize the function; if the functional requirement of the system is a three (two) axis accelerometer, Then remove the gyroscope circuit, and assemble it from bottom to top according to the control circuit and the -accelerometer circuit; if the system function requirement is three (two) axis gyroscopes, remove the accelerometer circuit, and follow the control circuit and -gyroscope circuit from bottom to bottom Stack up assembly. If you want to expand the measurement function, you can design the circuit board according to the existing signal interface, such as adding geomagnetism, inclinometer circuit board, etc. It is also possible to extend the function of the control circuit board, add a navigation module, and transform the micro-inertial measurement component into a micro-inertial navigation component.

Since the internal electronic components of the system are laminated and assembled with specially designed elastomer support materials, the mechanical protection of the micro-inertial measurement unit in the large overload and high dynamic environment is realized, and the information interconnection between the circuit boards is carried out through the flexible conduction belt to ensure reliability of the electrical interface. At the same time, the layered structure and the information interconnection method make the function of the micro-inertial measurement unit flexible and expandable.

It should be understood that the above-mentioned specific embodiments of the present invention are only used to illustrate or explain the principle of the present invention, but not to limit the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and scope of the present invention should be included within the protection scope of the present invention. Furthermore, the appended claims of this invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalents of such scope and boundaries.

Claims (8)

1. The stacked micro-inertia measurement unit under the large-overload high-dynamic application environment comprises at least two circuit boards, wherein at least one type of inertia sensor is arranged on each circuit board, the circuit boards are fixed in a stacked mode through an elastic support structure, the elastic support structure comprises a fixing portion and an elastic portion, the elastic portion is made of elastic materials, the circuit boards are electrically interconnected through a flexible conduction band connector, the flexible conduction band connector comprises a flexible conduction band, and the length of the flexible conduction band is larger than the distance between the circuit boards.

2. The stacked micro inertial measurement unit under a high overload and high dynamic application environment according to claim 1, wherein the material parameters of the elastic material are designed according to the application environment to ensure that the deformation of the elastic part is in an elastic range in a large overload stage.

3. The stacked micro inertial measurement unit under a large overload and high dynamic application environment of claim 2, wherein the damping characteristic of the elastic material and the system natural frequency are calculated so that the damping characteristic of the elastic material is inconsistent with the system natural frequency.

4. The stacked micro inertial measurement unit under high-overload and high-dynamic application environment according to claim 1, wherein the fixing portion is connected with the elastic portion through a mosaic structure and fixedly connected through glue.

5. The stacked micro inertial measurement unit in a high overload and dynamic application environment according to claim 1, wherein the elastic support structure is a circular truncated cone structure, and the fixing part is provided with a thread.

6. The stacked micro-inertia measurement unit under a large-overload high-dynamic application environment according to claim 1, wherein the flexible conduction band connector further comprises a golden finger pad structure and a plastic body structure, internal routing copper foils are led out from two ends of the flexible conduction band, a golden finger pad with a certain strength is formed through thickening, and the golden finger pad and a part of the flexible conduction band are subjected to injection molding to obtain the plastic body structure.

7. The stacked micro inertial measurement unit in a high overload and high dynamic application environment of claim 1, wherein the control circuit board is connected to the electrical structure connector through a flexible conductive strip connector.

8. The stacked micro inertial measurement unit under a high-overload and high-dynamic application environment according to claim 1, wherein a metal shell is arranged on the periphery of the stacked micro inertial measurement unit, and the metal shell comprises a square sleeve and a planar base, and a mounting flange is arranged on each side of the square sleeve and the planar base.

Images