Accelerometer system online parameter identification method based on digital phase-locked loop

Abstract

The invention belongs to the technical field of accelerometer second-order system identification, and particularly discloses an accelerometer system online parameter identification method based on a digital phase-locked loop, which comprises the following steps: in a first displacement signal detection stage, applying a first excitation signal to a mass block in an accelerometer through electromagnetic excitation, and detecting a first displacement signal of the mass block, the phase difference between the first displacement signal and the first excitation signal is determined as a reference phase difference, and the frequency of the excitation signal in the first displacement signal detection stage is fixed in a preset frequency range; in the second displacement signal detection stage, a second displacement signal of the mass block is detected, the target phase difference is tracked through the digital phase-locked loop, the difference between the target phase difference and the reference phase difference is # imgabs0 #, and the frequency of the excitation signal in the second displacement signal detection stage is larger than the preset frequency upper limit; and after the phase-locked loop is stable, determining the eigenfrequency and the quality factor of the accelerometer. According to the invention, rapid online parameter identification of the accelerometer system is realized.

Description

Technical Field

[0001] The present application belongs to the technical field of accelerometer second-order system identification, and more specifically, relates to an online parameter identification method of an accelerometer system based on a digital phase-locked loop. Background Art

[0002] Accelerometers are sensors used to measure the acceleration of objects and are widely used in inertial navigation, attitude control, vibration detection and other fields. Although there are many types of accelerometer sensors, such as piezoelectric, capacitive, piezoresistive, thermal convection, etc., their detection principle is mainly based on the second-order low-pass system of "mass-damper-spring". Dynamically identifying the acceleration second-order system during the sensing process helps analyze the working state of the accelerometer, which is of great significance for practical applications.

[0003] The dynamic parameter identification methods of traditional accelerometers can be divided into time domain identification and frequency domain identification. The time domain identification is mainly based on ISO 16063-12:2001 "Absolute shock excitation calibration standard" by collecting the response data of the accelerometer system under standard pulse shock, and further using the least squares method, intelligent optimization algorithm and other algorithms to obtain the model parameters; the frequency domain identification is mainly based on ISO 16063-11:1999 "Calibration method for vibration and shock sensors" by using steady-state sinusoidal vibration and laser interferometry, and then using the sine approximation method, fringe counting method, and minimum point method to obtain the accelerometer frequency response function.

[0004] However, the traditional identification process has the following difficulties: the identification process is time-consuming, which is not conducive to the long-term stable monitoring of the accelerometer; the accelerometer sensing process will be disturbed by non-ideal factors such as delay, nonlinearity, and noise, which will affect the generation of ideal data; the standard excitation relies on the ideal impact signal generated by a large impact vibration table; the fitting data selection process relies too much on experience, and manual data processing is required to judge the data identification results.

[0005] A high-precision identification method for the dynamic model parameters of a digital accelerometer is proposed in the related art. By collecting the response data of the accelerometer under the closed-loop feedback state, a nonlinear dynamic mathematical model of the delay term is established, and the fitting approximation is gradually performed through the intelligent optimization iterative algorithm, so that the error data is close to the noise characteristics of the digital capacitive accelerometer. However, this method still belongs to offline identification and requires manual offline data processing. How to realize online parameter identification of accelerometer systems is a technical problem that needs to be solved urgently in this field. Summary of the invention

[0006] In view of the defects of the prior art, the purpose of the present application is to realize online parameter identification of an accelerometer system.

[0007] To achieve the above objectives, in a first aspect, the present application provides an online parameter identification method for an accelerometer system based on a digital phase-locked loop, comprising: In the first displacement signal detection stage, a first excitation signal is applied to the mass block in the accelerometer through electromagnetic excitation, a first displacement signal of the mass block is detected, and the first excitation signal is used as a reference signal to perform phase discrimination on the displacement signal, and a phase difference between the first displacement signal and the first excitation signal is determined as a reference phase difference. The frequency of the excitation signal in the first displacement signal detection stage is a fixed frequency, and the fixed frequency is within a preset frequency range, and the preset frequency range is 0 Hz to a preset frequency upper limit; In the second displacement signal detection stage, the first excitation signal is applied to the mass block in the accelerometer through electromagnetic excitation, the second displacement signal of the mass block is detected, and the first excitation signal is used as a reference signal to perform phase discrimination on the displacement signal, determine the phase difference between the second displacement signal and the first excitation signal, and adjust the frequency of the excitation signal by tracking the target phase difference through a digital phase-locked loop. The difference between the target phase difference and the reference phase difference is , the frequency of the excitation signal in the second displacement signal detection stage is greater than a preset frequency upper limit; When the digital phase-locked loop is stable, the natural frequency and the quality factor of the accelerometer are determined based on the first displacement signal and the second displacement signal.

[0008] In a possible implementation, detecting a displacement signal of a mass block includes: Acquire sensing parameters from the accelerometer, the sensing parameters are used to characterize the displacement of the mass block, and the sensing parameters change with the displacement of the mass block; The displacement signal corresponding to the sensing parameter is obtained by accessing the lookup table, and the lookup table is used to represent the corresponding relationship between the displacement signal and the sensing parameter.

[0009] In one possible implementation, the lookup table is constructed by the following steps: The mass block is driven to perform a specified displacement by electromagnetic excitation; When the mass block performs a specified displacement, a sensing parameter corresponding to the specified displacement is obtained from the accelerometer; Record the specified displacement and the sensing parameters corresponding to the specified displacement into the lookup table.

[0010] In a possible implementation, using the first excitation signal as a reference signal to perform phase discrimination on the displacement signal to determine a phase difference between the displacement signal and the first excitation signal includes: Based on the first excitation signal and the second excitation signal, phase demodulate the displacement signal to obtain an in-phase component and an orthogonal component corresponding to the displacement signal; Based on the in-phase component and the orthogonal component corresponding to the displacement signal, a phase difference calculation is performed to determine the phase difference between the displacement signal and the first excitation signal; The first excitation signal and the second excitation signal are a group of sine and cosine signals, and the first excitation signal and the second excitation signal have the same amplitude and the same frequency and are orthogonal.

[0011] In a possible implementation, determining an eigenfrequency and a quality factor of an accelerometer based on the first displacement signal and the second displacement signal includes: Based on the frequency of the second displacement signal, an eigenfrequency of the accelerometer is determined, and based on the amplitude of the first displacement signal and the amplitude of the second displacement signal, a quality factor of the accelerometer is determined.

[0012] In a second aspect, the present application provides an online parameter identification device for an accelerometer system based on a digital phase-locked loop, comprising: a digitally controlled oscillator, an electromagnetic excitation module, a displacement detection module, a phase identification module, a digital phase-locked loop, and an online parameter identification module; The digitally controlled oscillator is used to generate a first excitation signal, the frequency of the excitation signal in the first displacement signal detection stage is a fixed frequency, the fixed frequency is in a preset frequency range, the preset frequency range is 0 Hz to a preset frequency upper limit, and the frequency of the excitation signal in the second displacement signal detection stage is greater than the preset frequency upper limit; The electromagnetic excitation module is used to apply a first excitation signal to a mass block in the accelerometer to drive the mass block to move; The displacement detection module is used to detect a first displacement signal of the mass block in a first displacement signal detection phase, and to detect a second displacement signal of the mass block in a second displacement signal detection phase; The phase identification module is used to perform phase identification on the displacement signal with the first excitation signal as the reference signal, determine the phase difference between the first displacement signal and the first excitation signal, and use the phase difference determined in the first displacement signal detection stage as the reference phase difference; The digital phase-locked loop is used to adjust the frequency of the excitation signal in the second displacement signal detection stage by tracking the target phase difference. The difference between the target phase difference and the reference phase difference is ; The online parameter identification module is used to determine the natural frequency and quality factor of the accelerometer based on the first displacement signal and the second displacement signal when the digital phase-locked loop is stable.

[0013] In a possible implementation, the displacement detection module is used to: Acquire sensing parameters from the accelerometer, the sensing parameters are used to characterize the displacement of the mass block, and the sensing parameters change with the displacement of the mass block; The displacement signal corresponding to the sensing parameter is obtained by accessing the lookup table, and the lookup table is used to represent the corresponding relationship between the displacement signal and the sensing parameter.

[0014] In a possible implementation, a lookup table building module is further included, which is used to: The mass block is driven to perform a specified displacement by electromagnetic excitation; When the mass block performs a specified displacement, a sensing parameter corresponding to the specified displacement is obtained from the accelerometer; Record the specified displacement and the sensing parameters corresponding to the specified displacement into the lookup table.

[0015] In a possible implementation, the phase identification module includes: a dual-phase demodulator and a phase detector; The digital controlled oscillator is also used to generate a second excitation signal, the first excitation signal and the second excitation signal are a set of sine and cosine signals, the first excitation signal and the second excitation signal have the same amplitude and the same frequency and are orthogonal; The dual-phase demodulator is used to perform phase demodulation on the displacement signal based on the first excitation signal and the second excitation signal to obtain an in-phase component and an orthogonal component corresponding to the displacement signal; The phase detector is used to calculate the phase difference based on the in-phase component and the orthogonal component corresponding to the displacement signal, and determine the phase difference between the displacement signal and the first excitation signal.

[0016] In a possible implementation, the online parameter identification module is specifically used for: Based on the frequency of the second displacement signal, an eigenfrequency of the accelerometer is determined, and based on the amplitude of the first displacement signal and the amplitude of the second displacement signal, a quality factor of the accelerometer is determined.

[0017] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art: (1) Through the first displacement signal detection stage, the first displacement signal can be obtained when the frequency of the excitation signal is 0 Hz or low frequency. The first displacement signal can characterize the amplitude-frequency-phase-frequency response characteristics of the accelerometer under DC or low frequency. Through the second displacement signal detection stage, the second displacement signal can be obtained when the frequency of the excitation signal is the center frequency. The second displacement signal can characterize the amplitude-frequency-phase-frequency response characteristics of the accelerometer at the center frequency. By combining the first displacement signal and the second displacement signal, amplitude and phase analysis can be performed to determine the intrinsic frequency and quality factor of the accelerometer, thereby realizing fast online parameter identification of the accelerometer system, avoiding noise interference in long-term calibration, and without the need for external ideal shocks.

[0018] (2) By accessing the lookup table, the displacement corresponding to the sensor parameter can be accurately obtained, thereby improving the accuracy of online parameter identification. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is one of the flow charts of the online parameter identification method of the accelerometer system based on the digital phase-locked loop provided in the embodiment of the present application; Figure 2 is an orthogonal digital data conversion diagram of an orthogonal digitally controlled oscillator provided in an embodiment of the present application; Figure 3 This is the second flow chart of the method for online parameter identification of an accelerometer system based on a digital phase-locked loop provided in an embodiment of the present application; Figure 4 is a schematic diagram of online parameter identification for a second-order underdamped accelerometer system provided in an embodiment of the present application; Figure 5 It is a schematic diagram of the fitting results of the online parameter identification process provided in the embodiment of the present application. DETAILED DESCRIPTION

[0020] In order to facilitate a clearer understanding of the embodiments of the present application, some relevant background knowledge is first introduced as follows.

[0021] For the second-order equivalent model of the accelerometer, the acceleration-displacement transfer function is expressed as follows: ; in Represents the complex frequency domain variables in the Laplace domain. Parameter identification requires determining the eigenfrequency of the second-order acceleration system. and quality factor .

[0022] In order to facilitate the analysis of system parameters, its frequency domain response can be written as follows: ; Its amplitude-frequency response and phase-frequency response can be written as follows: ; ; At DC or low frequency ( ) under the frequency-amplitude phase frequency response, using the amplitude angle information can be equivalently written as: ; At the center frequency (eigenfrequency), its amplitude-frequency-phase frequency response can be written as: ; Generally speaking, for a high-performance accelerometer system, It is often as high as several hundred. At this time, for the displacement detection of the mass block in the accelerometer, whether it is the displacement detection in the capacitive accelerometer or the displacement detection in the resistive accelerometer, there will often be a large nonlinearity, which will affect the accuracy of the calibration. Capacitive accelerometers use capacitance as a sensing parameter to characterize the displacement of the mass block, and there is a large nonlinearity between displacement and capacitance. Resistive accelerometers use resistance as a sensing parameter to characterize the displacement of the mass block, and there is a large nonlinearity between displacement and resistance.

[0023] For example, in the process of capacitance detection, the transfer relationship from displacement to capacitance is often nonlinear, and its expression is as follows: ; in, represents displacement, Represents capacitance, and other parameters are preset constants.

[0024] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0025] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0026] In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more than two. For example, multiple processing units refer to two or more processing units, etc.; multiple elements refer to two or more elements, etc.

[0027] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0028] Figure 1 FIG. 1 is a flow chart of an online parameter identification method for an accelerometer system based on a digital phase-locked loop provided in an embodiment of the present application. Figure 1 As shown, the method includes the following steps S101, S102 and S103.

[0029] Step S101, in a first displacement signal detection stage, applying a first excitation signal to a mass block in the accelerometer through electromagnetic excitation, detecting a first displacement signal of the mass block, and using the first excitation signal as a reference signal to perform phase discrimination on the displacement signal, determining a phase difference between the first displacement signal and the first excitation signal as a reference phase difference, the frequency of the excitation signal in the first displacement signal detection stage is a fixed frequency, the fixed frequency is in a preset frequency range, and the preset frequency range is 0 Hz to a preset frequency upper limit; Step S102, in the second displacement signal detection stage, a first excitation signal is applied to the mass block in the accelerometer by electromagnetic excitation, a second displacement signal of the mass block is detected, and the first excitation signal is used as a reference signal to perform phase discrimination on the displacement signal, determine the phase difference between the second displacement signal and the first excitation signal, and adjust the frequency of the excitation signal by tracking the target phase difference through a digital phase-locked loop (PLL). The difference between the target phase difference and the reference phase difference is , the frequency of the excitation signal in the second displacement signal detection stage is greater than a preset frequency upper limit; Step S103 : when the digital phase-locked loop is stable, determine the natural frequency and quality factor of the accelerometer based on the first displacement signal and the second displacement signal (measured when the digital phase-locked loop is in a stable state).

[0030] For online parameter identification, "online" means that the device under test (such as the accelerometer under test) is in an operating state, and online parameter identification means that the parameters of the device under test are identified while the device under test is in an operating state.

[0031] It can be understood that according to the above DC or low frequency amplitude-frequency phase-frequency response formula , and the amplitude-frequency-phase-frequency response formula at the above center frequency It can be seen that through the first displacement signal detection stage, the first displacement signal can be obtained when the frequency of the excitation signal is 0Hz or low frequency, and the first displacement signal can characterize the amplitude-frequency-phase-frequency response characteristics of the accelerometer under DC or low frequency. Through the second displacement signal detection stage, the second displacement signal can be obtained when the frequency of the excitation signal is the center frequency. The second displacement signal can characterize the amplitude-frequency-phase-frequency response characteristics of the accelerometer at the center frequency. By combining the first displacement signal and the second displacement signal, amplitude and phase analysis can be performed to determine the intrinsic frequency and quality factor of the accelerometer, so as to realize quick online parameter identification of the accelerometer system, avoid noise interference in long-term calibration, and do not require external ideal shock.

[0032] In a possible implementation, detecting the (first / second) displacement signal of the mass block includes: acquiring a sensing parameter (capacitance value or resistance value, etc.) from an accelerometer, the sensing parameter being used to characterize the displacement of the mass block, and the sensing parameter changing with the displacement of the mass block; The displacement signal corresponding to the sensing parameter is obtained by accessing the lookup table, and the lookup table is used to represent the corresponding relationship between the displacement signal and the sensing parameter.

[0033] In one possible implementation, the lookup table is constructed by the following steps: The mass block is driven to perform a specified displacement by electromagnetic excitation; When the mass block performs a specified displacement, a sensing parameter corresponding to the specified displacement is obtained from the accelerometer; Record the specified displacement and the sensing parameters corresponding to the specified displacement into the lookup table.

[0034] In a possible implementation, using the first excitation signal as a reference signal to perform phase discrimination on the displacement signal, and determining a phase difference between the (first / second) displacement signal and the first excitation signal, includes: Based on the first excitation signal and the second excitation signal, phase demodulate the displacement signal to obtain an in-phase component and an orthogonal component corresponding to the displacement signal; Based on the in-phase component and the orthogonal component corresponding to the displacement signal, a phase difference calculation is performed to determine the phase difference between the displacement signal and the first excitation signal; The first excitation signal and the second excitation signal are a group of sine and cosine signals, and the first excitation signal and the second excitation signal have the same amplitude and the same frequency and are orthogonal.

[0035] Exemplarily, when the first excitation signal is a sine signal, the second excitation signal is a cosine signal; and when the first excitation signal is a cosine signal, the second excitation signal is a sine signal.

[0036] Figure 2 is an orthogonal digital data conversion diagram of the orthogonal digital controlled oscillator provided in the embodiment of the present application, such as Figure 2 As shown, a set of sine and cosine signals can be generated by an orthogonal digitally controlled oscillator. The orthogonal digitally controlled oscillator can adopt direct digital synthesis (DDS). DDS is a technology for generating waveform signals and is widely used in signal processing, communication and electronic equipment.

[0037] Orthogonal digital data conversion: In DDS, orthogonal digital data conversion mainly refers to the process of generating sine waves and cosine waves. Since there is a 90-degree phase difference between sine waves and cosine waves, the generation of orthogonal signals can be achieved through the following steps: phase generation, waveform search, and signal output. Phase generation: The phase accumulator generates a linearly increasing phase value (such as Figure 2 The quantized phase N in the waveform table represents the phase at the current time point, usually expressed in binary. Waveform search: Use the phase value as an index to obtain the corresponding sine and cosine wave amplitude values ​​from the waveform lookup table. Output signal: Send the sine and cosine wave amplitude values ​​obtained from the search to the DAC to generate an analog signal.

[0038] In a possible implementation, determining the eigenfrequency and quality factor of the accelerometer based on the first displacement signal and the second displacement signal includes: Based on the frequency of the second displacement signal, an eigenfrequency of the accelerometer is determined, and based on the amplitude of the first displacement signal and the amplitude of the second displacement signal, a quality factor of the accelerometer is determined.

[0039] The following is a description of the online parameter identification method of an accelerometer system based on a digital phase-locked loop provided in the present application through several examples.

[0040] Figure 3 FIG. 2 is a flow chart of an online parameter identification method for an accelerometer system based on a digital phase-locked loop provided in an embodiment of the present application. Figure 3 As shown, step 1: establish the second-order equivalent model of the accelerometer, and the transfer function from acceleration to displacement is expressed as follows: ; in, Represents the complex frequency domain variables in the Laplace domain. Parameter identification requires determining the eigenfrequency of the second-order acceleration system. and quality factor .

[0041] Step 2: To perform nonlinear calibration, a nonlinear fitting lookup table between displacement and sensing parameters (such as capacitance or resistance, etc.) is established. The mass block in the accelerometer is driven to perform a specified displacement by electromagnetic excitation, and the sensing parameters under the specified displacement are recorded to establish a nonlinear fitting lookup table between displacement and sensing parameters. Nonlinear calibration in the displacement detection process can be completed by using the lookup table in reverse. In the displacement detection process, based on the sensing parameters provided by the accelerometer, the displacement corresponding to the sensing parameters can be accurately obtained by accessing the above lookup table, thereby improving the accuracy of online parameter identification.

[0042] Step 3: Scan the low-frequency response image of the sensor, write a numerically controlled oscillator in the program, and apply a low-frequency sinusoidal excitation signal through electromagnetic excitation , detect the amplitude of the displacement signal The phase detector identifies the phase difference between the sinusoidal excitation signal and the displacement signal, and sets the phase difference at this time to 0. The phase difference at this time can be called the reference phase difference.

[0043] Step 4: Turn on the digital phase-locked loop, which receives the phase difference output by the phase detector and adjusts the output frequency of the digital controlled oscillator through the (feedback loop) , to track the target phase difference, the difference between the target phase difference and the reference phase difference The frequency of the electromagnetic excitation is Sinusoidal excitation signal , detect the amplitude of the displacement signal , after the phase-locked loop is stable (the difference between the target phase difference and the reference phase difference is ), the frequency of the numerically controlled oscillator is the eigenfrequency , at this time the AC amplitude ( ) and low frequency amplitude ( The quality factor .

[0044] Figure 4 is a schematic diagram of online parameter identification for a second-order underdamped accelerometer system provided in an embodiment of the present application, such as Figure 3 and 4 As shown, in step 2, the DAC is controlled by the calibration signal, and the frequency is swept within different voltage ranges to obtain the nonlinearity of capacitance detection and supplement the nonlinear fitting lookup table.

[0045] In step 3, the DAC is controlled by a numerically controlled oscillator (NCO). At this time, the input of the numerically controlled oscillator is the set low-frequency control word, which generates a low-frequency sinusoidal excitation signal. At this time, the digital dual-phase demodulator completes the extraction of the in-phase component and the orthogonal component respectively. Then, the phase detector identifies the phase difference between the sinusoidal excitation signal and the displacement signal based on the in-phase component and the orthogonal component, and sets the phase difference at this time to 0 (the phase difference at this time can be called the reference phase difference). The amplitude of the displacement signal at this time is saved as .

[0046] The input of the dual-phase demodulator is the two reference signals (sine excitation signal and cosine excitation signal) provided by the NCO and the displacement signal at the current moment obtained by accessing the lookup table; the dual-phase demodulator is used to phase demodulate the displacement signal based on the sine excitation signal and the cosine excitation signal to obtain the in-phase component corresponding to the displacement signal and orthogonal components The output of the dual-phase demodulator is the in-phase component and the orthogonal components .

[0047] The input of the phase detector is the in-phase component and the orthogonal components The phase detector is used to calculate the phase difference based on the in-phase component and the orthogonal component corresponding to the displacement signal, and determine the phase difference between the displacement signal and the sinusoidal excitation signal. Specifically, the phase difference and the amplitude of the displacement signal can be calculated by the following formula: ; ; in, represents the phase difference, represents the amplitude of the displacement signal, It is the amplitude representation of the displacement signal in the polar coordinate system.

[0048] In step 4, the input frequency control word of the numerically controlled oscillator is generated by the phase-locked loop. The phase-locked loop is based on the frequency control byte that generates a phase difference of 90° relative to the previous moment. After the system is stable (the phase difference at this time can be called the target phase difference, and the target phase difference is 90° different from the reference phase difference), the amplitude of the displacement signal at this time can be recorded as .

[0049] The input of the phase-locked loop is the phase difference provided by the phase detector, and the output is the frequency control word M. By adjusting the frequency control word M, the target phase difference can be tracked.

[0050] Figure 5 is a schematic diagram of the fitting results of the online parameter identification process provided in the embodiment of the present application, such as Figure 5 As shown, it can be seen that the eigenfrequency of the acceleration second-order system can be quickly identified online through the online parameter identification method of the accelerometer system based on the digital phase-locked loop provided by the present application. and quality factor .

[0051] The following is a description of the online parameter identification device of an accelerometer system based on a digital phase-locked loop provided in the present application. The online parameter identification device of an accelerometer system based on a digital phase-locked loop described below and the online parameter identification method of an accelerometer system based on a digital phase-locked loop described above can be referred to each other.

[0052] The present application also provides an online parameter identification device for an accelerometer system based on a digital phase-locked loop, comprising: a digitally controlled oscillator, an electromagnetic excitation module, a displacement detection module, a phase identification module, a digital phase-locked loop and an online parameter identification module; The digitally controlled oscillator is used to generate a first excitation signal, the frequency of the excitation signal in the first displacement signal detection stage is a fixed frequency, the fixed frequency is in a preset frequency range, the preset frequency range is 0 Hz to a preset frequency upper limit, and the frequency of the excitation signal in the second displacement signal detection stage is greater than the preset frequency upper limit; The electromagnetic excitation module is used to apply a first excitation signal to a mass block in the accelerometer to drive the mass block to move; The displacement detection module is used to detect a first displacement signal of the mass block in a first displacement signal detection phase, and to detect a second displacement signal of the mass block in a second displacement signal detection phase; The phase identification module is used to perform phase identification on the displacement signal with the first excitation signal as the reference signal, determine the phase difference between the first displacement signal and the first excitation signal, and use the phase difference determined in the first displacement signal detection stage as the reference phase difference; The digital phase-locked loop is used to adjust the frequency of the excitation signal in the second displacement signal detection stage by tracking the target phase difference. The difference between the target phase difference and the reference phase difference is ; The online parameter identification module is used to determine the natural frequency and quality factor of the accelerometer based on the first displacement signal and the second displacement signal (measured when the digital phase-locked loop is in a stable state) when the digital phase-locked loop is stable.

[0053] In a possible implementation, the displacement detection module is used to: Obtaining sensing parameters (capacitance value or resistance value, etc.) from the accelerometer. The sensing parameters are used to characterize the displacement of the mass block, and the sensing parameters change with the displacement of the mass block; The displacement signal corresponding to the sensing parameter is obtained by accessing the lookup table, and the lookup table is used to represent the corresponding relationship between the displacement signal and the sensing parameter.

[0054] In a possible implementation, a lookup table building module is further included, which is used to: The mass block is driven to perform a specified displacement by electromagnetic excitation; When the mass block performs a specified displacement, a sensing parameter corresponding to the specified displacement is obtained from the accelerometer; Record the specified displacement and the sensing parameters corresponding to the specified displacement into the lookup table.

[0055] In a possible implementation, the phase identification module includes: a dual-phase demodulator and a phase detector; The digital controlled oscillator is also used to generate a second excitation signal, the first excitation signal and the second excitation signal are a set of sine and cosine signals, the first excitation signal and the second excitation signal have the same amplitude and the same frequency and are orthogonal; The dual-phase demodulator is used to perform phase demodulation on the displacement signal based on the first excitation signal and the second excitation signal to obtain an in-phase component and an orthogonal component corresponding to the displacement signal; The phase detector is used to calculate the phase difference based on the in-phase component and the orthogonal component corresponding to the displacement signal, and determine the phase difference between the displacement signal and the first excitation signal.

[0056] In a possible implementation, the online parameter identification module is specifically used to: determine the eigenfrequency of the accelerometer based on the frequency of the second displacement signal, and determine the quality factor of the accelerometer based on the amplitude of the first displacement signal and the amplitude of the second displacement signal.

[0057] It can be understood that the detailed functional implementation of each of the above-mentioned units / modules can be found in the introduction of the aforementioned method embodiment, and will not be repeated here.

[0058] It should be understood that the above-mentioned device is used to execute the method in the above-mentioned embodiment. The implementation principle and technical effect of the corresponding program module in the device are similar to those described in the above-mentioned method. The working process of the device can refer to the corresponding process in the above-mentioned method, which will not be repeated here.

[0059] It should be understood that the various numerical numbers involved in the embodiments of the present application are only used for the convenience of description and are not used to limit the scope of the embodiments of the present application.

[0060] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. An online parameter identification method for an accelerometer system based on a digital phase-locked loop, characterized in that: include: In the first displacement signal detection stage, a first excitation signal is applied to the mass block in the accelerometer through electromagnetic excitation, a first displacement signal of the mass block is detected, and the first excitation signal is used as a reference signal to perform phase discrimination on the displacement signal, and a phase difference between the first displacement signal and the first excitation signal is determined as a reference phase difference. The frequency of the excitation signal in the first displacement signal detection stage is a fixed frequency, and the fixed frequency is within a preset frequency range, and the preset frequency range is 0 Hz to a preset frequency upper limit; In the second displacement signal detection stage, the first excitation signal is applied to the mass block in the accelerometer through electromagnetic excitation, the second displacement signal of the mass block is detected, and the first excitation signal is used as a reference signal to perform phase discrimination on the displacement signal, determine the phase difference between the second displacement signal and the first excitation signal, and adjust the frequency of the excitation signal by tracking the target phase difference through a digital phase-locked loop. The difference between the target phase difference and the reference phase difference is , the frequency of the excitation signal in the second displacement signal detection stage is greater than a preset frequency upper limit; When the digital phase-locked loop is stable, the natural frequency and the quality factor of the accelerometer are determined based on the first displacement signal and the second displacement signal.

2. The method for online parameter identification of an accelerometer system based on a digital phase-locked loop according to claim 1, characterized in that: Detect the displacement signal of the mass block, including: Acquire sensing parameters from the accelerometer, the sensing parameters are used to characterize the displacement of the mass block, and the sensing parameters change with the displacement of the mass block; The displacement signal corresponding to the sensing parameter is obtained by accessing the lookup table, and the lookup table is used to represent the corresponding relationship between the displacement signal and the sensing parameter.

3. The method for online parameter identification of an accelerometer system based on a digital phase-locked loop according to claim 2, characterized in that: The lookup table is constructed by the following steps: The mass block is driven to perform a specified displacement by electromagnetic excitation; When the mass block performs a specified displacement, a sensing parameter corresponding to the specified displacement is obtained from the accelerometer; Record the specified displacement and the sensing parameters corresponding to the specified displacement into the lookup table.

4. The method for online parameter identification of an accelerometer system based on a digital phase-locked loop according to claim 1, characterized in that: The first excitation signal is used as a reference signal to perform phase discrimination on the displacement signal to determine the phase difference between the displacement signal and the first excitation signal, including: Based on the first excitation signal and the second excitation signal, phase demodulate the displacement signal to obtain an in-phase component and an orthogonal component corresponding to the displacement signal; Based on the in-phase component and the orthogonal component corresponding to the displacement signal, a phase difference calculation is performed to determine the phase difference between the displacement signal and the first excitation signal; The first excitation signal and the second excitation signal are a group of sine and cosine signals, and the first excitation signal and the second excitation signal have the same amplitude and the same frequency and are orthogonal.

5. The method for online parameter identification of an accelerometer system based on a digital phase-locked loop according to claim 1, characterized in that: The determining of the eigenfrequency and the quality factor of the accelerometer based on the first displacement signal and the second displacement signal comprises: Based on the frequency of the second displacement signal, an eigenfrequency of the accelerometer is determined, and based on the amplitude of the first displacement signal and the amplitude of the second displacement signal, a quality factor of the accelerometer is determined.

6. An online parameter identification device for an accelerometer system based on a digital phase-locked loop, characterized in that: include: Digitally controlled oscillator, electromagnetic excitation module, displacement detection module, phase discrimination module, digital phase-locked loop and online parameter identification module; The digitally controlled oscillator is used to generate a first excitation signal, the frequency of the excitation signal in the first displacement signal detection stage is a fixed frequency, the fixed frequency is in a preset frequency range, the preset frequency range is 0 Hz to a preset frequency upper limit, and the frequency of the excitation signal in the second displacement signal detection stage is greater than the preset frequency upper limit; The electromagnetic excitation module is used to apply a first excitation signal to a mass block in the accelerometer to drive the mass block to move; The displacement detection module is used to detect a first displacement signal of the mass block in a first displacement signal detection phase, and to detect a second displacement signal of the mass block in a second displacement signal detection phase; The phase identification module is used to perform phase identification on the displacement signal with the first excitation signal as the reference signal, determine the phase difference between the first displacement signal and the first excitation signal, and use the phase difference determined in the first displacement signal detection stage as the reference phase difference; The digital phase-locked loop is used to adjust the frequency of the excitation signal in the second displacement signal detection stage by tracking the target phase difference. The difference between the target phase difference and the reference phase difference is ; The online parameter identification module is used to determine the natural frequency and quality factor of the accelerometer based on the first displacement signal and the second displacement signal when the digital phase-locked loop is stable.

7. The accelerometer system online parameter identification device based on a digital phase-locked loop according to claim 6, characterized in that: The displacement detection module is used for: Acquire sensing parameters from the accelerometer, the sensing parameters are used to characterize the displacement of the mass block, and the sensing parameters change with the displacement of the mass block; The displacement signal corresponding to the sensing parameter is obtained by accessing the lookup table, and the lookup table is used to represent the corresponding relationship between the displacement signal and the sensing parameter.

8. The accelerometer system online parameter identification device based on a digital phase-locked loop according to claim 7, characterized in that: Also included are lookup table building blocks for: The mass block is driven to perform a specified displacement by electromagnetic excitation; When the mass block performs a specified displacement, a sensing parameter corresponding to the specified displacement is obtained from the accelerometer; Record the specified displacement and the sensing parameters corresponding to the specified displacement into the lookup table.

9. The accelerometer system online parameter identification device based on a digital phase-locked loop according to claim 6, characterized in that: The phase identification module includes: a dual-phase demodulator and a phase detector; The digital controlled oscillator is also used to generate a second excitation signal, the first excitation signal and the second excitation signal are a set of sine and cosine signals, the first excitation signal and the second excitation signal have the same amplitude and the same frequency and are orthogonal; The dual-phase demodulator is used to perform phase demodulation on the displacement signal based on the first excitation signal and the second excitation signal to obtain an in-phase component and an orthogonal component corresponding to the displacement signal; The phase detector is used to calculate the phase difference based on the in-phase component and the orthogonal component corresponding to the displacement signal, and determine the phase difference between the displacement signal and the first excitation signal.

10. The online parameter identification device for an accelerometer system based on a digital phase-locked loop according to claim 6, characterized in that: The online parameter identification module is specifically used for: Based on the frequency of the second displacement signal, an eigenfrequency of the accelerometer is determined, and based on the amplitude of the first displacement signal and the amplitude of the second displacement signal, a quality factor of the accelerometer is determined.

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