Bandwidth-extended micromechanical gyroscope open-loop detection method and open-loop detection system

Abstract

The application discloses a bandwidth-extended micro-mechanical gyroscope open-loop detection method and an open-loop detection system, and the method comprises the following steps: calculating the Coriolis force of a micro-mechanical gyroscope detection mode and a detection mode output signal according to an input angular velocity, and inputting the detection mode output signal to a low-pass filter after modulation; output signals of the low-pass filter are sequentially transmitted to a notch filter for offsetting a mode frequency difference resonance peak and a second-order oscillation link for suppressing high-frequency noise, and the bandwidth-extended open-loop detection is completed; the notch filter and the second-order oscillation link are connected in series and then connected to the low-pass filter, so that the bandwidth extension of the micro-mechanical gyroscope open-loop detection is realized, the angular velocity open-loop detection bandwidth is no longer limited by the working mode frequency difference of the micro-mechanical gyroscope, the angular velocity open-loop detection bandwidth is improved, and meanwhile, the phase characteristic of the angular velocity open-loop detection is ensured.

Description

Technical Field

[0001] This invention belongs to the field of micromechanical gyroscopes, and particularly relates to a method and system for open-loop detection of micromechanical gyroscopes with extended bandwidth. Background Technology

[0002] Micromechanical gyroscopes are sensors that utilize microelectromechanical systems (MEMS) technology and the Coriolis effect to detect the rotational angular velocity of a gyroscope carrier. Compared to traditional mechanical and optical gyroscopes, micromechanical gyroscopes offer advantages such as small size, light weight, low cost, low power consumption, high reliability, and large-scale production. With the development of MEMS technology, micromechanical gyroscope technology has also made significant progress and is widely used in both civilian and military fields.

[0003] The micromechanical gyroscope comprises two operating modes: a driving mode and a sensing mode. Both modes can be considered as second-order systems of a "spring-mass-damping" architecture. The driving mode control loop uses an automatic gain controller and a phase-locked loop (PLL) to stabilize the modal vibration amplitude and track the resonant frequency. The sensing mode employs an open-loop sensing method, directly characterizing the input angular velocity by detecting the modal vibration displacement; this approach is simple and easy to implement.

[0004] The angular velocity detection bandwidth of the open-loop detection method is mainly determined by the frequency difference of the operating mode. For fabricated micromechanical gyroscopes, the mode frequency difference is a fixed value; therefore, the angular velocity detection bandwidth of the open-loop detection method is limited by the operating mode frequency difference. Furthermore, a common method for extending the open-loop detection bandwidth of micromechanical gyroscopes is to use a low-pass filter to suppress the resonance peak of the detection mode, which deteriorates the phase characteristics of the open-loop angular velocity detection. Summary of the Invention

[0005] Purpose of the invention: The first purpose of the invention is to provide an open-loop detection method for micromechanical gyroscopes that is not limited by the frequency difference of the working mode of the micromechanical gyroscope. The second purpose of the invention is to provide an open-loop detection system for micromechanical gyroscopes.

[0006] Technical solution: The bandwidth-extended micromechanical gyroscope open-loop detection method of the present invention includes the following steps:

[0007] (1) Input angular velocity, calculate Coriolis force and detection mode output signal of micromechanical gyroscope detection mode, and input the detection mode output signal into low-pass filter after modulation;

[0008] (2) The output signal of the low-pass filter is sequentially passed to a notch filter for canceling the mode frequency difference resonance peak and a second-order oscillation stage for suppressing high-frequency noise, thus completing the open-loop detection for bandwidth expansion; the notch filter is based on the driving mode resonance frequency ω of the micromechanical gyroscope. x Detecting the modal resonant frequency ω y And the quality factor Q of the detection modey A unit-gain notch filter calculated.

[0009] Preferably, the transfer function H n (s) of the notch filter is:

[0010]

[0011] where Δω is the frequency difference of the working mode of the micro-mechanical gyroscope, Δω = ω y -ω x ; A is a gain compensation coefficient, A = 1 / Δω.

[0012] Preferably, the transfer function H o (s) of the second-order oscillation link is:

[0013]

[0014] where ω b is the cross-over frequency of the second-order oscillation link, and ω b is greater than the expected angular velocity detection bandwidth of the micro-mechanical gyroscope; ζ is the damping ratio coefficient of the second-order oscillation link, s is a complex frequency.

[0015] Preferably, the transfer function of the detection mode of the micro-mechanical gyroscope is:

[0016]

[0017] where m c is the Coriolis mass of the micro-mechanical gyroscope, Δω is the frequency difference of the working mode of the micro-mechanical gyroscope, Δω = ω y -ω x , and s is a complex frequency.

[0018] The micro-mechanical gyroscope open-loop detection system provided by the application comprises a first open-loop detection unit and a bandwidth expansion unit connected in cascade.

[0019] The first open-loop detection unit comprises a gyroscope detection mode unit and a low-pass filter connected in cascade.

[0020] The bandwidth expansion unit comprises a notch filter and a second-order oscillation link connected in cascade, the notch filter is a unit-gain notch filter calculated according to the resonant frequency ω x of the drive mode, the resonant frequency ω y of the detection mode and the quality factor Q y of the detection mode of the micro-mechanical gyroscope, and the second-order oscillation link is used for suppressing high-frequency noise.

[0021] The electronic device comprises a memory, a processor, and a computer program stored in the memory and capable of running on the processor, and the computer program realizes the bandwidth-extended micro-mechanical gyroscope open-loop detection method when loaded to the processor.

[0022] The computer readable storage medium stores a computer program, and the computer program realizes the bandwidth-extended micro-mechanical gyroscope open-loop detection method when executed by the processor.

[0023] Advantages: Compared with the prior art, the bandwidth-extended micro-mechanical gyroscope open-loop detection method based on the notch filter makes the angular velocity open-loop detection bandwidth no longer limited by the working modal frequency difference of the micro-mechanical gyroscope, improves the angular velocity open-loop detection bandwidth, and guarantees the phase characteristics of the angular velocity open-loop detection. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The bandwidth-extended micro-mechanical gyroscope open-loop detection system block diagram of the present application.

[0025] Figure 2 The first open-loop detection unit system block diagram of the present application.

[0026] Figure 3 The amplitude-frequency characteristic curve diagram of the micro-mechanical gyroscope open-loop detection without bandwidth extension in the embodiment of the present application.

[0027] Figure 4 The amplitude-frequency characteristic curve diagram of the bandwidth-extended micro-mechanical gyroscope open-loop detection in the embodiment of the present application. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be further described below with reference to the drawings.

[0029] The bandwidth-extended micro-mechanical gyroscope open-loop detection method comprises the following steps:

[0030] (1) Obtain the drive modal resonance frequency ω x , the detection modal resonance frequency ω y , and the quality factor Q y of the detection modal of the micro-mechanical gyroscope.

[0031] (2) Design a unit-gain notch filter according to the working modal resonance frequency, the frequency difference thereof, and the quality factor of the detection modal as follows:

[0032]

[0033] wherein Δω is the working modal frequency difference of the micro-mechanical gyroscope, and Δω = ω y - ωx A is a gain compensation coefficient, and A = 1 / Δω, to ensure that the gain in the open-loop detection passband is constant, thereby making the scale factor of the open-loop detection of the micro-mechanical gyroscope constant;

[0034] (3) The second-order oscillation link for suppressing high-frequency noise is designed as follows:

[0035]

[0036] where ω b is the crossover frequency of the second-order oscillation link, and ω b should be greater than the expected angular velocity detection bandwidth of the micro-mechanical gyroscope, to ensure the effectiveness of the bandwidth expansion of the open-loop detection of the micro-mechanical gyroscope, and ζ is the damping ratio coefficient of the second-order oscillation link, and the damping ratio coefficient should satisfy to avoid the resonance peak introduced by the second-order oscillation link, thereby affecting the effectiveness of the bandwidth expansion.

[0037] (4) The unit gain notch filter and the second-order oscillation link are connected in series to the first open-loop detection path, i.e., the open-loop detection path of the micro-mechanical gyroscope without bandwidth expansion, to achieve the bandwidth expansion of the open-loop detection of the micro-mechanical gyroscope.

[0038] The first open-loop detection method is as follows:

[0039] The transfer function of the detection mode of the micro-mechanical gyroscope is:

[0040]

[0041] where m c is the Coriolis mass of the micro-mechanical gyroscope, ω y is the resonance frequency of the detection mode, Q y is the quality factor of the detection mode, and Δω is the operating mode frequency difference.

[0042] Let the input angular velocity of the gyroscope be Ω(t), and the Coriolis force of the detection mode is:

[0043]

[0044] where A x is the stable vibration amplitude of the drive mode, and ω x is the resonance frequency of the drive mode.

[0045] The Laplace transform of equation (4) is as follows:

[0046] F c (s) = jm c A x ω x [Ω(s-jω x t)-Ω(s+jωx t) (5)

[0047] The output signal of the detection mode of the micromechanical gyroscope is:

[0048] Y s (s) = j m c A x ω x [Ω(s - jω x t) - Ω(s + jω x t)]G s (s) (6)

[0049] The signal of the output signal of the detection mode after modulation is:

[0050]

[0051] The Laplace transform of equation (7) is:

[0052]

[0053] Substituting equation (6) into equation (8) can obtain:

[0054]

[0055] The frequency of the input angular velocity Ω(t) of the micromechanical gyroscope is much smaller than the resonance frequency ω x of the drive mode, and after filtering out the double frequency signal by a low-pass filter, it can be simplified as:

[0056]

[0057] Substituting equation (3) into equation (10), the angular velocity open-loop detection transfer function without using bandwidth expansion method can be obtained:

[0058]

[0059] Wherein

[0060]

[0061]

[0062]

[0063]

[0064] Generally, the quality factor Q y of the detection mode of the micromechanical gyroscope is greater than 0.5, Δω is greater than 0.2ω x , and the input angular velocity is much smaller than the resonance frequency of the working mode, so there is the following relationship:

[0065]

[0066] According to the above relationship, formula (11) can be simplified as:

[0067]

[0068] In order to improve the open-loop detection bandwidth of the micromechanical gyroscope, the bandwidth expansion method is used, a notch filter and a second-order oscillation link are connected in series after a low-pass filter, and the open-loop detection transfer function of the micromechanical gyroscope after the bandwidth expansion method is obtained as:

[0069]

[0070] Based on the same inventive concept, as shown in Figure 1 , the bandwidth expanded micromechanical gyroscope open-loop detection system of the application comprises a first open-loop detection unit and a bandwidth expansion unit connected in cascade; as shown in Figure 2 is a system block diagram of the first open-loop detection unit, the first open-loop detection unit comprises a gyroscope detection mode unit and a low-pass filter connected in cascade; the bandwidth expansion unit comprises a notch filter and a second-order oscillation link connected in cascade, the notch filter is a unity gain notch filter calculated according to the drive mode resonance frequency ω x , the detection mode resonance frequency ω y and the quality factor Q y of the detection mode of the micromechanical gyroscope; the second-order oscillation link is used to suppress high-frequency noise.

[0071] In formula (17), let

[0072]

[0073] According to formula (17), the frequency corresponding to the +3dB point of the open-loop detection amplitude-frequency characteristic curve without bandwidth expansion is:

[0074]

[0075] According to formula (17), the frequency corresponding to the -3dB point of the open-loop detection amplitude-frequency characteristic curve without bandwidth expansion is:

[0076]

[0077] For the micromechanical gyroscope with high quality factor of the working mode, the open-loop detection amplitude-frequency characteristic curve without bandwidth expansion is shown in Figure 3 . Since the resonance peak at the mode frequency difference Δω is high, the open-loop detection bandwidth without bandwidth expansion is the frequency ω b1. In the ideal state, the resonance peak of the open-loop detection amplitude-frequency characteristic curve after bandwidth expansion is completely suppressed, and the amplitude of the amplitude-frequency characteristic curve decreases from the decibel value at a frequency of 0 Hz to a frequency ω b2 for detecting the bandwidth.

[0078] According to formula (18), the amplitude-frequency characteristic of the micro-mechanical gyroscope open-loop detection after the bandwidth expansion method is obtained, and the amplitude-frequency characteristic curve of the bandwidth expansion micro-mechanical gyroscope open-loop detection is as shown in Figure 4 The notch filter suppresses the resonance peak of the micro-mechanical gyroscope open-loop detection transfer function, improves the bandwidth of the micro-mechanical gyroscope open-loop detection, and suppresses high-frequency noise through a second-order oscillation link.

Claims

1. A bandwidth-extended open-loop detection method for micromechanical gyroscopes, characterized in that, Includes the following steps: (1) Input angular velocity, calculate Coriolis force and detection mode output signal of micromechanical gyroscope detection mode, and input the detection mode output signal into low-pass filter after modulation; (2) The output signal of the low-pass filter is sequentially passed to a notch filter for canceling the mode frequency difference resonance peak and a second-order oscillation stage for suppressing high-frequency noise, thus completing the open-loop detection for bandwidth expansion; the notch filter is based on the driving mode resonance frequency ω of the micromechanical gyroscope. x Detecting the modal resonant frequency ω y And the quality factor Q of the detection mode y Calculated unity-gain notch filter; The transfer function H of the notch filter n (s) is: Where Δω is the frequency difference of the operating mode of the micromechanical gyroscope, Δω=ω y -ω x A is the gain compensation coefficient, A = 1 / Δω; The transfer function H of the second-order oscillating element o (s) is: Where ω b Let ω be the transition frequency of the second-order oscillatory element. b The angular velocity detection bandwidth is greater than that expected for a micromechanical gyroscope; ζ is the damping ratio coefficient of the second-order oscillating element. s is a complex frequency.

2. The bandwidth-extended micromechanical gyroscope open-loop detection method according to claim 1, characterized in that, The transfer function of the detection mode of the micromechanical gyroscope is: Where m c Let Δω be the Coriolis mass of the micromechanical gyroscope, and Δω be the frequency difference of the operating mode of the micromechanical gyroscope, where Δω = ω y -ω x s is a complex frequency.

3. A micromechanical gyroscope open-loop detection system, characterized in that, Includes a cascaded first open-loop detection unit and a bandwidth expansion unit; The first open-loop detection unit includes a cascaded gyroscope detection mode unit and a low-pass filter; The bandwidth extension unit includes a cascaded notch filter and a second-order oscillating element. The notch filter is based on the driving mode resonant frequency ω of the micromechanical gyroscope. x Detecting the modal resonant frequency ω y And the quality factor Q of the detection mode y The calculated unity-gain notch filter; the second-order oscillating element is used to suppress high-frequency noise; The transfer function H of the notch filter n (s) is: Where Δω is the frequency difference of the operating mode of the micromechanical gyroscope, Δω=ω y -ω x A is the gain compensation coefficient, A = 1 / Δω; The transfer function H of the second-order oscillating element o (s) is: Where ω b Let ω be the transition frequency of the second-order oscillatory element. b The angular velocity detection bandwidth is greater than that expected for a micromechanical gyroscope; ζ is the damping ratio coefficient of the second-order oscillating element. s is a complex frequency.

4. An electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the computer program is loaded into the processor, it implements the bandwidth-extended micromechanical gyroscope open-loop detection method according to any one of claims 1-2.

5. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the bandwidth-extended micromechanical gyroscope open-loop detection method according to any one of claims 1-2.

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