Micromechanical gyroscope resonance signal filtering method

Abstract

The invention belongs to the technical field of inertial sensing, and particularly relates to a micromechanical gyroscope resonance signal filtering method which comprises the following steps: setting a sampling frequency according to the resonance frequency of a micromechanical gyroscope, and requiring that the sampling frequency is greater than twice of the resonance frequency; designing a filter transfer function; discretizing the transfer function into a difference equation; calculating a filter coefficient; and sampling the gyro signal according to the set sampling frequency, processing the sampled signal according to the parameter of the filter, and finally obtaining the filtered signal. The second-order filter is adopted, the calculation amount is small, engineering implementation is easy, the filtering efficiency is high, the signal attenuation can reach-20db near the resonant frequency of the gyroscope, and the influence of the gyroscope resonance distortion signal on the measurement precision can be effectively filtered out.

Description

Technical Field

[0001] The present invention belongs to the technical field of inertial sensing, and particularly relates to a method for filtering resonant signals of a micro-machined gyroscope. Background Art

[0002] A micro-machined gyroscope is a fully solid-state vibrating gyroscope. Under an external vibration environment, its output will be distorted. Especially near the resonant frequency point of the gyroscope, the output of the gyroscope will show a large peak band; as Figure 1 shown.

[0003] Currently, the main methods for eliminating resonant signals of micro-machined gyroscopes are structural vibration damping or using FIR or IIR low-pass filters. However, structural vibration damping will bring additional hardware costs and increase the volume of the gyroscope, which is not conducive to applications in occasions with strict volume requirements; while the order of the FIR filter is high, requiring a very high-performance processor; the IIR filter has a large phase delay and cannot be applied to occasions requiring high-frequency response. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a method for filtering resonant signals of a micro-machined gyroscope, including:

[0005] S1. According to the resonant frequency of the micro-machined gyroscope, set the sampling frequency, and require the sampling frequency to be greater than twice the resonant frequency;

[0006] S2. Design the transfer function of the filter;

[0007] S3. Discretize the transfer function into a difference equation;

[0008] S4. Calculate the filter coefficients;

[0009] S5: Sample the gyro signal according to the set sampling frequency, process the sampled signal according to the parameters of the filter, and finally obtain the filtered signal.

[0010] Advantages of the present invention:

[0011] 1. Adopting a second-order filter, with small computational amount and easy to be implemented in engineering;

[0012] 2. Small filtering delay. Within the main working frequency of 100 Hz of the gyroscope, the delay time is less than 0.05 ms. Compared with the millisecond-level delay of the gyroscope itself, the filtering delay can be ignored.

[0013] 3. High filtering efficiency. Near the resonant frequency of the gyroscope, the signal attenuation can reach -20 dB, which can effectively filter the influence of the gyro resonant distortion signal on the measurement accuracy. Description of the Drawings

[0014] Figure 1Schematic diagram of the output curve of a micromechanical gyroscope under an external vibration environment;

[0015] Figure 2 Flowchart of a method for testing the resonant frequency of a micromechanical gyroscope according to the present invention;

[0016] Figure 3 Schematic diagram of calculating filter coefficients using MATLAB according to the present invention. Specific implementation manners

[0017] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0018] The present invention proposes a method for filtering resonant signals of a micromechanical gyroscope, as Figure 2 shown, which specifically includes the following steps:

[0019] S1. According to the resonant frequency of the micromechanical gyroscope, set the sampling frequency (f0), and it is required that the sampling frequency is greater than twice the resonant frequency;

[0020] S2. Design the filter transfer function as:

[0021]

[0022] where H(s) is the filter transfer function, s represents the Laplace variable, ξ n represents the numerator damping coefficient, ξ d represents the denominator damping coefficient, and ω n represents the angular frequency.

[0023] S3. Discretize the transfer function into a difference equation:

[0024] y(n) = b0x[n] + b1x[n - 1] + b2x[n - 2] - a1y[n - 1] - a2y[n - 2]

[0025] where y(n) is the output sequence after filtering the gyro signal, x(n) is the original output sequence of the gyro signal, and b0, b1, b2, a1, and a2 are the first, second, third, fourth, and fifth filter coefficients.

[0026] S4. Calculate the filter coefficients;

[0027] According to the frequency width, amplitude and main working frequency (mostly ≤ 100 Hz) of the resonant signal of the micromechanical gyroscope, the molecular damping coefficient is preferably 0.005 and the denominator damping coefficient is 0.05, and the MATLAB is used to calculate the filtering coefficient, such as Figure 3 as shown.

[0028] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A filtering method for the resonant signal of a micromachined gyroscope, characterized in that Including: S1. Set the sampling frequency according to the resonant frequency of the micromachined gyroscope, and require that the sampling frequency is greater than twice the resonant frequency; S2. Design the transfer function of the filter; S3. Discretize the transfer function into a difference equation; S4. Calculate the filter coefficients; S5: Sample the gyro signal according to the set sampling frequency, process the sampled signal according to the parameters of the filter, and finally obtain the filtered signal.

2. A resonant signal filtering method for a micromechanical gyroscope according to claim 1, characterized in that, Designing the transfer function of the filter includes: Among them, H(s) is the filter transfer function, s represents the Laplace variable, and ξ n represents the numerator damping coefficient, and ξ d represents the denominator damping coefficient, and ω n represents the angular frequency.

3. A method for filtering resonant signals of a micromechanical gyroscope according to claim 1, characterized in that, Discretizing the transfer function into a difference equation includes: y(n) = b0x[n] + b1x[n - 1] + b2x[n - 2] - a1y[n - 1] - a2y[n - 2] where y(n) is the output sequence of the gyro signal after filtering, x(n) is the original output sequence of the gyro signal, and b0, b1, b2, a1, a2 are the first, second, third, and fourth filter coefficients.

4. A method for filtering resonance signals of a micromachined gyroscope according to claim 1, characterized in that, Calculating the filter coefficients includes: According to the frequency width, amplitude, and main operating frequency of the resonant signal of the micromachined gyro, preferably select the molecular damping coefficient to be 0.005 and the denominator damping coefficient to be 0.05, and use MATLAB to calculate the filter coefficients.

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