An online parameter identification method for accelerometer system based on digital phase-locked loop

Abstract

The present application belongs to the technical field of accelerometer second-order system identification, and specifically discloses an online parameter identification method for an accelerometer system based on a digital phase-locked loop, comprising: in a first displacement signal detection stage, applying a first excitation signal to a mass block in the accelerometer through electromagnetic excitation, detecting the first displacement signal of the mass block, and determining the phase difference between the first displacement signal and the first excitation signal as a reference phase difference, wherein the frequency of the excitation signal in the first displacement signal detection stage is fixed within a preset frequency range; in a second displacement signal detection stage, detecting the second displacement signal of the mass block and tracking the target phase difference through a digital phase-locked loop, wherein the target phase difference differs from the reference phase difference by a factor of #imgabs0#, and the frequency of the excitation signal in the second displacement signal detection stage is greater than a preset frequency upper limit; after the phase-locked loop stabilizes, determining the eigenfrequency and quality factor of the accelerometer. The present application enables quick online parameter identification of the accelerometer system.

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 for an accelerometer system based on a digital phase-locked loop. Background Art

[0002] Accelerometers are sensors used to measure an object's acceleration and are widely used in inertial navigation, attitude control, vibration detection, and other fields. While there are many different types of accelerometer sensors, such as piezoelectric, capacitive, piezoresistive, and thermal convection, their detection principle is primarily based on a second-order, low-pass "mass-damper-spring" system. Dynamically identifying this second-order acceleration system during the sensing process helps analyze the accelerometer's operating status and 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. 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 least squares method, intelligent optimization algorithm and other algorithms to obtain model parameters; frequency domain identification is mainly based on ISO 16063-11:1999 "Calibration method of vibration and shock sensors" by using steady-state sinusoidal vibration and laser interferometry, and then using 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 interfered with by non-ideal factors such as delay, nonlinearity, and noise, which affects the generation of ideal data; the standard excitation relies on the ideal shock signal generated by a large shock vibration table; the fitting data selection and processing relies too much on experience, and manual data processing is required to judge the data identification results.

[0005] A related technique has been proposed for high-precision identification of dynamic model parameters of digital accelerometers. This method collects accelerometer response data under closed-loop feedback, establishes a nonlinear dynamic mathematical model of the delay term, and uses an intelligent optimization iterative algorithm to gradually approximate the error data, ensuring that it approximates the noise characteristics of the digital capacitive accelerometer. However, this method still involves offline identification and requires manual offline data processing. Implementing online parameter identification for accelerometer systems is a pressing technical challenge in this field. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this application is to realize online parameter identification of 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:

[0008] In a first displacement signal detection stage, a first excitation signal is applied to a mass block in the accelerometer through electromagnetic excitation, a first displacement signal of the mass block is detected, and phase discrimination is performed on the displacement signal using the first excitation signal as a reference 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;

[0009] 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 the preset frequency upper limit;

[0010] 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.

[0011] In one possible implementation, detecting a displacement signal of a mass block includes:

[0012] 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.

[0013] 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 one possible implementation, the lookup table is constructed by the following steps:

[0015] The mass is driven to perform a specified displacement by electromagnetic excitation;

[0016] When the mass block performs a specified displacement, the sensing parameter corresponding to the specified displacement is obtained from the accelerometer;

[0017] Record the specified displacement and the sensing parameters corresponding to the specified displacement into a lookup table.

[0018] In one possible implementation, performing phase discrimination on the displacement signal using the first excitation signal as a reference signal to determine a phase difference between the displacement signal and the first excitation signal includes:

[0019] Based on the first excitation signal and the second excitation signal, phase demodulate the displacement signal to obtain an in-phase component and a quadrature component corresponding to the displacement signal;

[0020] Performing phase difference calculation based on the in-phase component and the quadrature component corresponding to the displacement signal to determine the phase difference between the displacement signal and the first excitation signal;

[0021] 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.

[0022] In one possible implementation, determining the eigenfrequency and quality factor of the accelerometer based on the first displacement signal and the second displacement signal includes:

[0023] An eigenfrequency of the accelerometer is determined based on the frequency of the second displacement signal, and a quality factor of the accelerometer is determined based on the amplitude of the first displacement signal and the amplitude of the second displacement signal.

[0024] 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;

[0025] 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, and the fixed frequency is within a preset frequency range, and the preset frequency range is from 0 Hz to a preset frequency upper limit. The frequency of the excitation signal in the second displacement signal detection stage is greater than the preset frequency upper limit.

[0026] 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;

[0027] 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;

[0028] The phase identification module is used to perform phase identification on the displacement signal using the first excitation signal as a 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;

[0029] 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 ;

[0030] 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.

[0031] In one possible implementation, the displacement detection module is used to:

[0032] 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.

[0033] 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.

[0034] In a possible implementation, a lookup table building module is further included, configured to:

[0035] The mass is driven to perform a specified displacement by electromagnetic excitation;

[0036] When the mass block performs a specified displacement, the sensing parameter corresponding to the specified displacement is obtained from the accelerometer;

[0037] Record the specified displacement and the sensing parameters corresponding to the specified displacement into a lookup table.

[0038] In one possible implementation, the phase identification module includes: a dual-phase demodulator and a phase detector;

[0039] The digitally controlled oscillator is further used to generate a second excitation signal, wherein the first excitation signal and the second excitation signal are a set 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 to each other;

[0040] 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 a quadrature component corresponding to the displacement signal;

[0041] The phase detector is used to calculate the phase difference based on the in-phase component and the quadrature component corresponding to the displacement signal, and determine the phase difference between the displacement signal and the first excitation signal.

[0042] In one possible implementation, the online parameter identification module is specifically used to:

[0043] An eigenfrequency of the accelerometer is determined based on the frequency of the second displacement signal, and a quality factor of the accelerometer is determined based on the amplitude of the first displacement signal and the amplitude of the second displacement signal.

[0044] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the existing technologies:

[0045] (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 shock.

[0046] (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

[0047] Figure 1 This 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;

[0048] Figure 2 is an orthogonal digital data conversion diagram of the orthogonal digitally controlled oscillator provided in an embodiment of the present application;

[0049] Figure 3 This is a second 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;

[0050] Figure 4 1 is a schematic diagram of online parameter identification for a second-order underdamped accelerometer system provided in an embodiment of the present application;

[0051] 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

[0052] In order to facilitate a clearer understanding of the various embodiments of the present application, some relevant background knowledge is first introduced as follows.

[0053] For the second-order equivalent model of the accelerometer, the acceleration-displacement transfer function is expressed as follows:

[0054] ;

[0055] 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 .

[0056] In order to facilitate the analysis of system parameters, its frequency domain response can be written as follows:

[0057] ;

[0058] Its amplitude-frequency response and phase-frequency response can be written as follows:

[0059] ;

[0060] ;

[0061] At DC or low frequency ( ) under the condition of its amplitude-frequency and phase-frequency response, the amplitude-angle information can be equivalently written as:

[0062] ;

[0063] At the center frequency (eigenfrequency), its amplitude-frequency and phase-frequency response can be written as:

[0064] ;

[0065] Generally speaking, for a high performance accelerometer system, its Often reaching several hundred, the displacement detection of the mass in the accelerometer often exhibits significant nonlinearity, affecting calibration accuracy, whether in capacitive or resistive accelerometers. Capacitive accelerometers use capacitance as the sensing parameter to characterize the displacement of the mass, resulting in a significant nonlinearity between displacement and capacitance. Resistive accelerometers use resistance as the sensing parameter to characterize the displacement of the mass, resulting in a significant nonlinearity between displacement and resistance.

[0066] For example, in the process of capacitance detection, the transfer relationship from displacement to capacitance is often nonlinear, and its expression is as follows:

[0067] ;

[0068] in, represents displacement, Represents capacitance, and other parameters are preset constants.

[0069] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0070] In the embodiments of this 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 this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0071] In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more, for example, multiple processing units means two or more processing units, etc.; multiple elements means two or more elements, etc.

[0072] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0073] Figure 1 This is one of the flow charts 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, such as Figure 1 As shown, the method includes the following steps S101, S102 and S103.

[0074] Step S101, in a first displacement signal detection phase, applying a first excitation signal to a mass in the accelerometer through electromagnetic excitation, detecting a first displacement signal of the mass, and performing phase discrimination on the displacement signal using the first excitation signal as a reference signal, determining a phase difference between the first displacement signal and the first excitation signal as a reference phase difference, wherein the frequency of the excitation signal in the first displacement signal detection phase is a fixed frequency, and the fixed frequency is within a preset frequency range, wherein the preset frequency range is 0 Hz to a preset frequency upper limit;

[0075] Step S102, in the second displacement signal detection phase, applies a first excitation signal to the mass block in the accelerometer through electromagnetic excitation, detects the second displacement signal of the mass block, and uses the first excitation signal as a reference signal to perform phase discrimination on the displacement signal, determines the phase difference between the second displacement signal and the first excitation signal, and adjusts 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 the preset frequency upper limit;

[0076] 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).

[0077] For online parameter identification, “online” means that the device under test (eg, the accelerometer under test) is in an operating state. Online parameter identification means that the parameters of the device under test are identified while the device under test is in an operating state.

[0078] 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 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 eigenfrequency 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.

[0079] In one possible implementation, detecting the (first / second) displacement signal of the mass block includes: acquiring a sensing parameter (such as a capacitance value or a resistance value) from an accelerometer, where the sensing parameter is used to characterize the displacement of the mass block, and the sensing parameter changes with the displacement of the mass block;

[0080] 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.

[0081] In one possible implementation, the lookup table is constructed by the following steps:

[0082] The mass is driven to perform a specified displacement by electromagnetic excitation;

[0083] When the mass block performs a specified displacement, the sensing parameter corresponding to the specified displacement is obtained from the accelerometer;

[0084] Record the specified displacement and the sensing parameters corresponding to the specified displacement into a lookup table.

[0085] In one possible implementation, performing phase discrimination on the displacement signal using the first excitation signal as a reference signal to determine a phase difference between the (first / second) displacement signal and the first excitation signal includes:

[0086] Based on the first excitation signal and the second excitation signal, phase demodulate the displacement signal to obtain an in-phase component and a quadrature component corresponding to the displacement signal;

[0087] Performing phase difference calculation based on the in-phase component and the quadrature component corresponding to the displacement signal to determine the phase difference between the displacement signal and the first excitation signal;

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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 ) at a fixed frequency (the frequency can be specified by the frequency control word M). Figure 2 The quantized phase N in the waveform lookup table represents the phase at the current time point, typically expressed as a binary number. Waveform search: Use the phase value as an index to retrieve the corresponding sine and cosine wave amplitudes from a waveform lookup table. Output signal: Send the resulting sine and cosine wave amplitudes to the DAC to generate an analog signal.

[0092] In one possible implementation, determining the eigenfrequency and quality factor of the accelerometer based on the first displacement signal and the second displacement signal includes:

[0093] An eigenfrequency of the accelerometer is determined based on the frequency of the second displacement signal, and a quality factor of the accelerometer is determined based on the amplitude of the first displacement signal and the amplitude of the second displacement signal.

[0094] The following is an illustrative example of the online parameter identification method for an accelerometer system based on a digital phase-locked loop provided in this application.

[0095] Figure 3This is a second 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, such as Figure 3 As shown, step 1: establish the second-order equivalent model of the accelerometer. The transfer function from acceleration to displacement is expressed as follows:

[0096] ;

[0097] 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 .

[0098] Step 2: To perform nonlinear calibration, a nonlinear fit lookup table is established between displacement and sensor parameters (such as capacitance or resistance). Electromagnetic excitation is used to drive the mass block in the accelerometer to a specified displacement. The sensor parameters at the specified displacement are recorded to establish a nonlinear fit lookup table between displacement and sensor parameters. Nonlinear calibration during displacement detection can be achieved by using the lookup table in reverse. During displacement detection, based on the sensor parameters provided by the accelerometer, the displacement corresponding to the sensor parameters can be accurately obtained by accessing the above lookup table, thereby improving the accuracy of online parameter identification.

[0099] 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. This phase difference at this time can be called the reference phase difference.

[0100] Step 4: Turn on the digital phase-locked loop (DPLL). The DPLL 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 applied frequency 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 ( ) is the quality factor .

[0101] Figure 4is 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 performs frequency sweeping in different voltage ranges to obtain the nonlinearity of capacitance detection and supplement the nonlinear fitting lookup table.

[0102] In step three, 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 .

[0103] 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 orthogonal components .

[0104] The input of the phase detector is the in-phase component and orthogonal components The phase detector is used to calculate the phase difference based on the in-phase component and quadrature 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 using the following formula:

[0105] ;

[0106] ;

[0107] in, represents the phase difference, represents the amplitude of the displacement signal, is the amplitude representation of the displacement signal in the polar coordinate system.

[0108] 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 stabilizes (the phase difference at this time can be called the target phase difference, which is 90° different from the reference phase difference), the amplitude of the displacement signal at this time can be recorded as .

[0109] 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 is tracked.

[0110] Figure 5 Schematic diagram of the fitting results of the online parameter identification process provided in the embodiment of the present application. 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 this application. and quality factor .

[0111] The following describes the online parameter identification device of the accelerometer system based on the digital phase-locked loop provided in the present application. The online parameter identification device of the accelerometer system based on the digital phase-locked loop described below and the online parameter identification method of the accelerometer system based on the digital phase-locked loop described above can refer to each other.

[0112] 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;

[0113] 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, and the fixed frequency is within a preset frequency range, and the preset frequency range is from 0 Hz to a preset frequency upper limit. The frequency of the excitation signal in the second displacement signal detection stage is greater than the preset frequency upper limit.

[0114] 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;

[0115] 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;

[0116] The phase identification module is used to perform phase identification on the displacement signal using the first excitation signal as a 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;

[0117] 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 ;

[0118] The online parameter identification module is used to determine the eigenfrequency 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.

[0119] In one possible implementation, the displacement detection module is used to:

[0120] Obtaining sensing parameters (capacitance or resistance, 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.

[0121] 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.

[0122] In a possible implementation, a lookup table building module is further included, configured to:

[0123] The mass is driven to perform a specified displacement by electromagnetic excitation;

[0124] When the mass block performs a specified displacement, the sensing parameter corresponding to the specified displacement is obtained from the accelerometer;

[0125] Record the specified displacement and the sensing parameters corresponding to the specified displacement into a lookup table.

[0126] In one possible implementation, the phase identification module includes: a dual-phase demodulator and a phase detector;

[0127] The digitally controlled oscillator is further used to generate a second excitation signal, wherein the first excitation signal and the second excitation signal are a set 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 to each other;

[0128] 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 a quadrature component corresponding to the displacement signal;

[0129] The phase detector is used to calculate the phase difference based on the in-phase component and the quadrature component corresponding to the displacement signal, and determine the phase difference between the displacement signal and the first excitation signal.

[0130] In one possible implementation, the online parameter identification module is specifically configured 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.

[0131] It is understandable that the detailed functional implementation of each of the above units / modules can be found in the introduction of the aforementioned method embodiment, and will not be repeated here.

[0132] 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 and will not be repeated here.

[0133] It will be understood that the various numerical numbers involved in the embodiments of the present application are merely distinctions for the convenience of description and are not intended to limit the scope of the embodiments of the present application.

[0134] It is easy for those skilled in the art to understand that the above 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 should 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 a first displacement signal detection stage, a first excitation signal is applied to a mass block in the accelerometer through electromagnetic excitation, a first displacement signal of the mass block is detected, and phase discrimination is performed on the displacement signal using the first excitation signal as a reference 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 the 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: Detection of 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 is driven to perform a specified displacement by electromagnetic excitation; When the mass block performs a specified displacement, the 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 a lookup table.

4. The method for online parameter identification of an accelerometer system based on a digital phase-locked loop according to claim 1, wherein: Performing phase discrimination on the displacement signal using the first excitation signal as a reference 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 a quadrature component corresponding to the displacement signal; Performing phase difference calculation based on the in-phase component and the quadrature component corresponding to the displacement signal 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 quality factor of the accelerometer based on the first displacement signal and the second displacement signal includes: An eigenfrequency of the accelerometer is determined based on the frequency of the second displacement signal, and a quality factor of the accelerometer is determined based on the amplitude of the first displacement signal and the amplitude of the second displacement signal.

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, and the fixed frequency is within a preset frequency range, and the preset frequency range is from 0 Hz to a preset frequency upper limit. 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 using the first excitation signal as a 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 is driven to perform a specified displacement by electromagnetic excitation; When the mass block performs a specified displacement, the 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 a 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 digitally controlled oscillator is further used to generate a second excitation signal, wherein the first excitation signal and the second excitation signal are a set 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 to each other; 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 a quadrature component corresponding to the displacement signal; The phase detector is used to calculate the phase difference based on the in-phase component and the quadrature 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: An eigenfrequency of the accelerometer is determined based on the frequency of the second displacement signal, and a quality factor of the accelerometer is determined based on the amplitude of the first displacement signal and the amplitude of the second displacement signal.

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