MEMS micromirror attitude detection control method integrating IMU and ASIC modules and integrated microsystem

Abstract

The invention discloses an MEMS micromirror attitude detection control method of an integrated IMU and ASIC module and an integrated microsystem, and relates to the technical field of MEMS and sensor integration, the device comprises a support layer, an isolation layer, a CMOS layer and a single-chip integrated structure arranged on the CMOS layer; the isolation layer is used for separating the supporting layer from the CMOS layer; the single-chip integrated structure is composed of an MEMS micromirror, an IMU module and an ASIC circuit. The IMU module comprises an accelerometer and a gyroscope and is used for detecting attitude information of a measured object in real time; and the ASIC circuit is used for resolving the attitude error of the measured object according to the attitude information and dynamically adjusting the micro-mirror driving signal. According to the invention, the stability and precision of the MEMS laser radar can be improved.

Description

Technical Field

[0001] The present application relates to the field of micro-electromechanical systems and sensor integration technology, and in particular to a MEMS micromirror attitude detection and control method and an integrated microsystem integrating an IMU and an ASIC module. Background Art

[0002] MEMS lidar uses semiconductor technology to integrate MEMS micromirrors, actuators, and other components onto millimeter-scale chips. This enables miniaturization (reduced to 1 / 10 the size), cost reduction (unit price <$200), and high performance. This overcomes the bottlenecks of traditional mechanical radar, which are large size, high cost, and poor reliability, and accelerates the commercialization of Level 2+ / L3 autonomous driving. It empowers the high-precision environmental perception industry chain for applications such as automobiles, drones, and robots, contributing to the development of the global smart sensor market. Furthermore, through multi-sensor fusion and 5G / AI collaboration, it reshapes smart transportation and urban management systems, reducing traffic accident rates by over 90%. This technology boasts both economic and social benefits, becoming a key infrastructure for the intelligent era. MEMS micromirrors are the core components of MEMS lidar. Fabricated using micromachining techniques, they are optical devices capable of high-precision angle control. Common actuation methods include electrostatic, electrothermal, electromagnetic, and piezoelectric. Due to their miniaturization, low power consumption, and high response speed, MEMS micromirrors are widely used in optical imaging, laser scanning, optical communications, and biomedical testing.

[0003] However, existing MEMS micromirror systems often lack real-time detection and feedback mechanisms for their posture information, and rely on open-loop or low-precision closed-loop control methods, making it difficult to achieve accurate automatic calibration and stable control. Summary of the Invention

[0004] The purpose of this application is to provide a MEMS micromirror attitude detection control method and integrated microsystem with integrated IMU and ASIC modules, which can provide high-precision attitude detection and real-time feedback, and improve the stability and accuracy of MEMS lidar.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] In a first aspect, the present application provides an integrated microsystem integrating an IMU and an ASIC module, comprising:

[0007] A supporting layer, an isolation layer, a CMOS layer, and a single-chip integrated structure arranged on the CMOS layer; the isolation layer is used to separate the supporting layer and the CMOS layer;

[0008] The single-chip integrated structure consists of a MEMS micromirror, an IMU module, and an ASIC circuit; the IMU module, including an accelerometer and a gyroscope, is used to detect the posture information of the measured object in real time; the ASIC circuit is used to calculate the posture error of the measured object based on the posture information and dynamically adjust the micromirror drive signal.

[0009] Optionally, it also includes several pads arranged on the surface of the ASIC circuit.

[0010] Optionally, it further includes comb teeth arranged directly below the MEMS micromirror; the comb teeth are used to realize one-dimensional deflection motion or two-dimensional deflection motion of the MEMS micromirror.

[0011] Optionally, two rows of comb teeth are provided directly below the MEMS micromirror.

[0012] Optionally, the MEMS micromirror is driven by electrostatic drive, piezoelectric drive, electrothermal drive or electromagnetic drive.

[0013] Optionally, the MEMS micromirror, accelerometer, and gyroscope communicate with the ASIC circuit via a metal layer in the CMOS layer.

[0014] In a second aspect, the present application provides a MEMS micromirror attitude detection and control method based on an integrated microsystem integrating an IMU and an ASIC module, comprising:

[0015] Obtain the posture information of the measured object detected by the IMU module;

[0016] According to the posture information, the posture information is solved using a quaternion or direction cosine matrix algorithm to obtain the three-dimensional spatial posture information of the measured object;

[0017] Based on the PID algorithm or adaptive control algorithm, the target posture of the measured object is compared with the three-dimensional spatial posture information of the current measured object, and the adjustment amount of the drive signal is calculated;

[0018] The deflection angle of the MEMS micromirror is adjusted according to the adjustment amount of the driving signal.

[0019] Optionally, according to the posture information, a quaternion algorithm is used to perform posture calculation on the posture information to obtain three-dimensional spatial posture information of the measured object, specifically including:

[0020] According to the posture information, based on the formula Performing posture calculation on the posture information to obtain three-dimensional spatial posture information of the measured object; the three-dimensional spatial posture information is represented by the current posture quaternion q;

[0021] Among them, q = [q0, q1, q2, q3] is the current posture quaternion; ωx 、ω y 、ω z is the angular velocity measured by the gyroscope; Represents quaternion multiplication.

[0022] Optionally, based on a PID algorithm or an adaptive control algorithm, the target posture of the measured object is compared with the three-dimensional spatial posture information of the current measured object, and an adjustment amount of the drive signal is calculated, specifically including:

[0023] Set the target attitude quaternion q target Quaternion error with the current attitude quaternion q

[0024] The quaternion error e q Convert to Euler angle error

[0025] The Euler angle error is input to the fuzzy PID controller, and according to the formula Output drive voltage adjustment amount ΔV.

[0026] Optionally, adjusting the deflection angle of the MEMS micromirror according to the adjustment amount of the driving signal specifically includes:

[0027] Adjusting the driving voltage according to the driving voltage adjustment amount to obtain an adjusted driving voltage;

[0028] According to the adjusted driving voltage, based on the formula Calculate the electrostatic driving torque of the MEMS micromirror; ∈0 is the dielectric constant of vacuum; A is the comb tooth overlap area; d is the comb tooth spacing;

[0029] According to the electrostatic driving torque of the MEMS micromirror, based on the formula Get the deflection angle of the MEMS mirror; where: J is the moment of inertia; C is the damping coefficient; K is the torsional stiffness; M disturbance is the external interference torque.

[0030] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0031] The present application provides a MEMS micromirror attitude detection control method and an integrated microsystem that integrates an IMU and an ASIC module. First, the device can detect the attitude information of the measured object, such as angle and acceleration, in real time by integrating an IMU module (including an accelerometer and a gyroscope), providing an accurate data basis for subsequent attitude error calculation. Secondly, the application of the ASIC circuit can quickly calculate the attitude error of the measured object based on the attitude information provided by the IMU module, and correct the attitude of the micromirror in real time by dynamically adjusting the driving signal of the MEMS micromirror, thereby ensuring stable emission and accurate scanning of the laser beam. In addition, the design of the single-chip integrated structure makes the connection between the MEMS micromirror, the IMU module and the ASIC circuit closer, reduces the delay and interference of signal transmission, and further improves the stability and accuracy of the system. The present application effectively improves the stability and accuracy of the MEMS lidar through innovative integrated technology and real-time attitude detection and correction methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 A schematic diagram of an integrated microsystem structure integrating an IMU and an ASIC module provided in one embodiment of the present application;

[0034] Figure 2(a) is a schematic diagram of the preparation process provided in one embodiment of the present application. Figure 1 ;

[0035] FIG2( b ) is a schematic diagram 2 of a preparation process provided in an embodiment of the present application;

[0036] Figure 2(c) is a schematic diagram of the preparation process provided in one embodiment of the present application. Figure 3 ;

[0037] Figure 3 A schematic diagram of a method flow chart provided in one embodiment of the present application.

[0038] Reference numerals:

[0039] 1-Accelerometer, 2-Pad, 3-CMOS layer, 4-Isolation layer, 5-Support layer, 6-ASIC circuit, 7-MEMS micromirror, 8-Comb teeth, 9-Gyroscope, 10-Silicon oxide, 11-Metal aluminum, 12-Through hole tungsten, 13-P-type substrate silicon, 14-ASIC control circuit. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0041] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0042] Example 1

[0043] like Figure 1 As shown, this embodiment provides an integrated microsystem integrating an IMU and an ASIC module, including:

[0044] A support layer 5, an isolation layer 4, a CMOS layer 3, and a single-chip integrated structure arranged on the CMOS layer 3; the isolation layer 4 is used to separate the support layer 5 and the CMOS layer 3;

[0045] The single-chip integrated structure is composed of a MEMS micromirror 7, an IMU module and an ASIC circuit 6; the IMU module includes an accelerometer 1 and a gyroscope 9, which are used to detect the posture information of the measured object in real time; the ASIC circuit 6 is used to calculate the posture error of the measured object based on the posture information and dynamically adjust the micromirror drive signal.

[0046] The device further includes a plurality of pads 2 disposed on the surface of the ASIC circuit 6 and comb teeth 8 disposed directly below the MEMS micromirror 7. The comb teeth 8 are used to achieve one-dimensional or two-dimensional deflection motion of the MEMS micromirror 7. Two rows of comb teeth 8 are disposed directly below the MEMS micromirror 7.

[0047] The inertial measurement unit (IMU), primarily composed of an accelerometer 1 and a gyroscope 9, measures an object's linear acceleration and angular velocity to infer its posture and motion in space. IMUs have important applications in high-precision positioning and dynamic attitude detection. By integrating the IMU module with the MEMS micromirror 7, real-time feedback can be used to dynamically adjust the micromirror's deflection angle, significantly improving the accuracy, stability, and robustness of LiDAR, providing technical support for expanding LiDAR applications.

[0048] The MEMS micromirror 7 is driven by electrostatics, piezoelectrics, electrothermals or electromagnetics.

[0049] The MEMS mirror 7, accelerometer 1 and gyroscope 9 communicate with the ASIC circuit 6 through the metal layer in the CMOS layer 3. Preferably, in this embodiment, a classical driving form is adopted, and the classical comb teeth 8 are used to realize the one-dimensional or two-dimensional deflection movement of the mirror. The accelerometer 1 and gyroscope 9 are integrated in the IMU module, which are respectively used to detect the gravitational acceleration and the angular velocity of the system. The MEMS mirror 7, accelerometer 1 and gyroscope 9 in the IMU all communicate with the ASIC circuit 6 through the metal layer in the CMOS and realize the real-time feedback of the attitude information. The ASIC integrates modules such as logic circuits and power distribution units, which are used to drive and detect the gyroscope 9 and accelerometer 1, and control the mirror through the attitude information provided by the gyroscope 9 and accelerometer 1. Among them, the ASIC circuit 6 is the control and detection center of the mirror, accelerometer 1 and gyroscope 9. The accelerometer 1 and gyroscope 9 detect the attitude information of the system and feedback it to the mirror control unit on the ASIC circuit 6 of the mirror to ensure that the reflected beam of the mirror always maintains the same direction.

[0050] Among them, Fig. 2(a), Fig. 2(b), and Fig. 2(c) show the ASIC circuit 6, the preparation process of the speedometer, the preparation process of the gyroscope 9, and the preparation process of the MEMS mirror 7.

[0051] First, use CMOS technology to pre-prepare the built-in aluminum leads and via tungsten 12, which are used as the lead structures of the mirror, gyro, and accelerometer 1. In addition, pre-manufacture the ASIC control circuit 14, and form the logic circuit through N-type ion implantation. In order to form the back cavity structures of the mirror, gyro, and accelerometer 1, dry etching is used to etch out the back cavity on the back. If the thickness of the substrate silicon is h and the depth of the back cavity is t, the remaining silicon thickness is h - t (t < h), as shown in Fig. 2(a); then dry etch the metal aluminum 10, such as using CHF3 or CF4 to etch the metal aluminum 10 to expose the substrate layer, as shown in Fig. 2(b); finally, use dry etching technology to etch the exposed P-type substrate silicon 13 from the front to release the entire device, as shown in Fig. 2(c).

[0052] Embodiment 2

[0053] As Figure 3 shown, this embodiment provides a method for detecting and controlling the attitude of a MEMS mirror based on an integrated micro-system integrating an IMU and an ASIC module, including:

[0054] Step 1: Obtain the attitude information of the measured object detected by the IMU module;

[0055] Step 2: According to the attitude information, use the quaternion or direction cosine matrix algorithm to perform attitude calculation on the attitude information to obtain the three-dimensional space attitude information of the measured object;

[0056] Step 3: Based on the PID algorithm or adaptive control algorithm, the target posture of the measured object is compared with the three-dimensional spatial posture information of the current measured object, and the adjustment amount of the drive signal is calculated;

[0057] Step 4: Adjust the deflection angle of the MEMS micromirror 7 according to the adjustment amount of the driving signal.

[0058] Among them, according to the posture information, the posture information is solved using the quaternion algorithm to obtain the three-dimensional spatial posture information of the measured object, which specifically includes:

[0059] According to the posture information, based on the formula Performing posture calculation on the posture information to obtain three-dimensional spatial posture information of the measured object; the three-dimensional spatial posture information is represented by the current posture quaternion q;

[0060] Among them, q = [q0, q1, q2, q3] is the current posture quaternion; ω x 、ω y 、ω z is the angular velocity measured by the gyroscope 9; Represents quaternion multiplication.

[0061] Then, the gravity direction predicted by the gravity vector g = [0,0,1] and the current posture quaternion q Compare it with the actual measurement value ameas of accelerometer 1, calculate the error, and correct the angular velocity integral drift.

[0062] Among them, based on the PID algorithm or adaptive control algorithm, the target posture of the measured object is compared with the three-dimensional spatial posture information of the current measured object, and the adjustment amount of the drive signal is calculated, specifically including:

[0063] Set the target attitude quaternion q target Quaternion error with the current attitude quaternion q

[0064] The quaternion error e q Convert to Euler angle error

[0065] The Euler angle error is input to the fuzzy PID controller, and according to the formula Output drive voltage adjustment ΔV. If the error e(t) is large and the error change rate d e / d t If it is positive, increase K p For fast response; if the error is close to zero and the rate of change is small, reduce Kp And improve K i To eliminate steady-state errors.

[0066] Adjusting the deflection angle of the MEMS micromirror 7 according to the adjustment amount of the driving signal specifically includes:

[0067] Adjusting the driving voltage according to the driving voltage adjustment amount to obtain an adjusted driving voltage;

[0068] According to the adjusted driving voltage, based on the formula Calculate the electrostatic driving torque of the MEMS micromirror 7; ∈0 is the dielectric constant of vacuum; A is the overlapping area of ​​the comb teeth 8; d is the spacing between the comb teeth 8;

[0069] According to the electrostatic driving torque of the MEMS micromirror 7, based on the formula The deflection angle of the MEMS micromirror 7 is obtained; wherein: J is the moment of inertia; C is the damping coefficient; K is the torsional stiffness; M disturbance is the external interference torque.

[0070] In addition, when the IMU detects a sudden change in angular acceleration, the drive voltage is instantaneously adjusted to:

[0071] V new =V nominal +ΔV comp

[0072] Among them, V new Real-time adjustment of driving power under vibration disturbance; V nominal is the normal input voltage when there is no vibration, that is, the nominal drive voltage; ΔV comp is the vibration compensation voltage increment, ΔV comp =K comp ·Δω;K comp is the vibration compensation coefficient; Δω is the sudden change of angular acceleration.

[0073] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. An integrated microsystem integrating IMU and ASIC modules, characterized in that: include: A supporting layer, an isolation layer, a CMOS layer, and a single-chip integrated structure arranged on the CMOS layer; the isolation layer is used to separate the supporting layer and the CMOS layer; The single-chip integrated structure consists of a MEMS micromirror, an IMU module, and an ASIC circuit; the IMU module, including an accelerometer and a gyroscope, is used to detect the posture information of the measured object in real time; the ASIC circuit is used to calculate the posture error of the measured object based on the posture information and dynamically adjust the micromirror drive signal.

2. The integrated microsystem integrating IMU and ASIC module according to claim 1, characterized in that: It also includes several pads arranged on the surface of the ASIC circuit.

3. The integrated microsystem integrating IMU and ASIC module according to claim 1, characterized in that: The invention also includes comb teeth arranged directly below the MEMS micromirror; the comb teeth are used to realize one-dimensional deflection motion or two-dimensional deflection motion of the MEMS micromirror.

4. The integrated microsystem integrating IMU and ASIC module according to claim 1, characterized in that: Two rows of comb teeth are arranged directly below the MEMS micromirror.

5. The integrated microsystem integrating IMU and ASIC module according to claim 1, characterized in that: The MEMS micromirror is driven by electrostatics, piezoelectrics, electrothermals or electromagnetics.

6. The integrated microsystem integrating IMU and ASIC module according to claim 1, characterized in that: The MEMS mirrors, accelerometers, and gyroscopes communicate with the ASIC circuits through the metal layer in the CMOS layer.

7. A method for controlling the attitude of a MEMS micromirror based on an integrated microsystem integrating an IMU and an ASIC module according to any one of claims 1 to 6, characterized in that: include: Obtain the posture information of the measured object detected by the IMU module; According to the posture information, the posture information is solved using a quaternion or direction cosine matrix algorithm to obtain the three-dimensional spatial posture information of the measured object; Based on the PID algorithm or adaptive control algorithm, the target posture of the measured object is compared with the three-dimensional spatial posture information of the current measured object, and the adjustment amount of the drive signal is calculated; The deflection angle of the MEMS micromirror is adjusted according to the adjustment amount of the driving signal.

8. The MEMS micromirror posture detection and control method according to claim 7, wherein: Based on the posture information, the posture information is solved using a quaternion algorithm to obtain the three-dimensional spatial posture information of the measured object, specifically including: According to the posture information, based on the formula Performing posture calculation on the posture information to obtain three-dimensional spatial posture information of the measured object; the three-dimensional spatial posture information is represented by the current posture quaternion q; Among them, q = [q0, q1, q2, q3] is the current posture quaternion; ω x 、ω y 、ω z is the angular velocity measured by the gyroscope; Represents quaternion multiplication.

9. The MEMS micromirror posture detection and control method according to claim 8, wherein: Based on the PID algorithm or adaptive control algorithm, the target posture of the measured object is compared with the three-dimensional spatial posture information of the current measured object, and the adjustment amount of the drive signal is calculated, specifically including: Set the target attitude quaternion q target Quaternion error with the current attitude quaternion q The quaternion error e q Convert to Euler angle error The Euler angle error is input to the fuzzy PID controller, and according to the formula Output drive voltage adjustment amount ΔV.

10. The MEMS micromirror posture detection and control method according to claim 9, wherein: Adjust the deflection angle of the MEMS mirror according to the adjustment amount of the driving signal, specifically including: Adjusting the driving voltage according to the driving voltage adjustment amount to obtain an adjusted driving voltage; According to the adjusted driving voltage, based on the formula Calculate the electrostatic driving torque of the MEMS micromirror; ∈0 is the dielectric constant of vacuum; A is the comb tooth overlap area; d is the comb tooth spacing; According to the electrostatic driving torque of the MEMS micromirror, based on the formula Get the deflection angle of the MEMS mirror; where: J is the moment of inertia; C is the damping coefficient; K is torsional stiffness; M disturbance is the external interference torque.

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