阅读说明：本技术 旋转加速度计重力梯度仪重力梯度解调相位角确定方法及装置 (Method and device for determining gravity gradient demodulation phase angle of gravity gradiometer of rotating accelerometer ) 是由 钱学武 赵立业 于 2020-06-30 设计创作，主要内容包括：本发明公开了一种旋转加速度计重力梯度仪重力梯度解调相位角确定方法及装置,属于精密测量领域。方法包括：首先对四只加速度计输出信号进行信号组合调理得到重力梯度模拟信号；然后A/D转换器根据角度信息转换器的同步脉冲信号对重力梯度模拟信号进行A/D转换,得到重力梯度数字信号；接下来利用参考信号源对重力梯度数字信号进行相位角解调,得到相位角数据序列；最后对相位角序列进行零相位低通滤波处理,并对滤波后的数据均值处理,得到准确的重力梯度解调相位角。使用本发明提供的重力梯度解调相位角确定方法,能够为后续的重力梯度解调提供精确的解调相位角,为进一步提高重力梯度测量精度提供了可能,同时操作简单方便,降低了研制成本。(The invention discloses a method and a device for determining a gravity gradient demodulation phase angle of a gravity gradiometer of a rotary accelerometer, and belongs to the field of precision measurement. The method comprises the following steps: firstly, carrying out signal combination conditioning on output signals of four accelerometers to obtain a gravity gradient analog signal; then the A/D converter performs A/D conversion on the gravity gradient analog signal according to the synchronous pulse signal of the angle information converter to obtain a gravity gradient digital signal; then, phase angle demodulation is carried out on the gravity gradient digital signal by using a reference signal source to obtain a phase angle data sequence; and finally, performing zero-phase low-pass filtering processing on the phase angle sequence, and performing mean processing on the filtered data to obtain an accurate gravity gradient demodulation phase angle. The gravity gradient demodulation phase angle determination method provided by the invention can provide an accurate demodulation phase angle for subsequent gravity gradient demodulation, provides possibility for further improving the gravity gradient measurement accuracy, is simple and convenient to operate, and reduces the development cost.)

1. A gravity gradient demodulation phase angle determination method for a gravity gradiometer of a rotary accelerometer, the method comprising the steps of:

carrying out signal combination conditioning on output signals of the four accelerometers to obtain gravity gradient analog signals;

the A/D converter performs A/D conversion on the gravity gradient analog signal according to the synchronous pulse signal sent by the angle information converter to obtain a gravity gradient digital signal;

and demodulating the phase angle of the gravity gradient digital signal by using a reference signal source to obtain a gravity gradient demodulation phase angle.

2. The method for determining the gravity gradient demodulation phase angle of the gravity gradiometer of the rotary accelerometer according to claim 1, wherein the digital gravity gradient signal obtained by the a/D conversion is expressed as:

in the formula, A_k、B_kAre the amplitudes of the 2k +1 th harmonic sine and cosine signals, C_k2k +2 harmonic signal amplitude, D is disc rotation angular acceleration amplitude, α is gravity gradient demodulation phase angle,

3. The method for determining the gravity gradient demodulation phase angle of the gravity gradiometer of the rotary accelerometer according to claim 2, wherein the phase angle demodulation of the gravity gradient digital signal by the reference signal source comprises:

generating a digital sine signal and a digital cosine signal as reference signals;

and 2, performing frequency multiplication amplitude demodulation on the output signal of the A/D converter by using the reference signal, and changing the initial phase angle of the reference signal until the maximum amplitude is obtained, wherein the initial phase angle at the moment is the gravity gradient demodulation phase angle.

4. The method for determining the gravity gradient demodulation phase angle of the gravity gradiometer of the rotary accelerometer according to claim 3, wherein the calculation expression of the gravity gradient demodulation phase angle is as follows:

in the formula, N is the pulse number output by the information converter every time the disk rotates one angle,ζ_ithe correction angles of the initial phase angles of the sine signal reference source and the cosine signal reference source at the ith time are respectively, the right side | max of the equation represents the initial phase angle of the signal reference source corresponding to the searched maximum value, S_s(k, i) is a digital sinusoidal signal, S_c(k, i) is a digital cosine signal,ζ_qand respectively demodulating phase angles for the gravity gradient obtained for the q-th time.

5. The method for rotational accelerometer gravity gradient demodulation phase angle determination according to any one of claims 1-4, further comprising: and carrying out zero-phase low-pass filtering processing on the gravity gradient demodulation phase angle obtained by demodulation, and carrying out average processing on the filtered data to obtain a final gravity gradient demodulation phase angle.

6. A device for determining a gravity gradient demodulation phase angle of a gravity gradiometer of a rotary accelerometer, comprising:

the signal conditioning module is used for carrying out signal combination conditioning on the output signals of the four accelerometers to obtain gravity gradient analog signals;

the A/D conversion module is used for carrying out A/D conversion on the gravity gradient analog signal according to the synchronous pulse signal sent by the angle information module to obtain a gravity gradient digital signal;

the angle information module is used for sending out a synchronous pulse signal;

and the phase angle demodulation module is used for demodulating the phase angle of the gravity gradient digital signal by using the reference signal source to obtain a gravity gradient demodulation phase angle.

7. The gravity gradient demodulation phase angle determination device of the gravity gradiometer of the rotary accelerometer according to claim 6, wherein the gravity gradient digital signal output by the a/D conversion module is expressed as:

in the formula, A_k、B_kAre the amplitudes of the 2k +1 th harmonic sine and cosine signals, C_k2k +2 harmonic signal amplitude, D is disc rotation angular acceleration amplitude, α is gravity gradient demodulation phase angle,to condition the delay angle caused by the delay of the path signal, φ is the first accelerometer A₁Initial angle between the gravity gradiometer and the x-axis of the gravity gradiometer coordinate system, theta is azimuth angle caused by environmental objects, delta t is sampling time, omega is the rotation angular frequency of the disk of the gravity gradiometer,

8. The rotational accelerometer gravity gradiometer gravity gradient demodulation phase angle determination apparatus of claim 6 wherein the phase angle demodulation module comprises:

a reference signal generating unit for generating a digital sine signal and a digital cosine signal as reference signals;

and the computing unit is configured to perform 2-frequency multiplication amplitude demodulation on the output signal of the A/D converter by using the reference signal, and change an initial phase angle of the reference signal until the maximum amplitude is obtained, wherein the initial phase angle is the gravity gradient demodulation phase angle.

9. The apparatus of claim 8, wherein the gravity gradient demodulation phase angle is calculated by the following expression:

in the formula, N is the pulse number output by the information converter every time the disk rotates one angle,ζ_ithe correction angles of the initial phase angles of the sine signal reference source and the cosine signal reference source at the ith time are respectively, the right side | max of the equation represents the initial phase angle of the sine signal reference source and the cosine signal reference source corresponding to the searched maximum value, S_s(k, i) is a digital sinusoidal signal, S_c(k, i) is a digital cosine signal,

10. The gravity gradient demodulation phase angle determination apparatus of a gravity gradiometer of a rotary accelerometer according to any of claims 6-9, further comprising a phase angle optimization module for performing zero-phase low-pass filtering processing on the demodulated gravity gradient demodulation phase angle and averaging the filtered data to obtain a final gravity gradient demodulation phase angle.

Technical Field

The invention belongs to the technical field of precision measurement, and particularly relates to a method and a device for determining a gravity gradient demodulation phase angle of a gravity gradiometer of a rotary accelerometer.

Background

The gravity gradient measurement technology has important significance for the research in the fields of space science, earth science, geological science, energy exploration, inertial navigation and the like. At present, the gravity gradiometers mainly include a rotary accelerometer gravity gradiometer, a superconducting gravity gradiometer, a cold atom gravity gradiometer, an electrostatic gravity gradiometer, a gravity gradiometer based on a micro-machining (MEMS) technology, and the like, wherein the rotary accelerometer gravity gradiometer is the only currently commercially available gravity gradiometer which is successfully used on an onboard/shipborne moving base.

The gravity gradiometer of the rotary accelerometer is a high-precision measuring instrument, the factors such as the stability of electronic elements, the electromagnetic compatibility problem of electronic circuits, the working performance of a sensor, the stability of a rotating mechanism, the temperature control performance and the like can cause serious influence on the measurement precision of the gravity gradiometer, and the factors can cause the output signal of the gravity gradiometer to contain various noises, thereby reducing the measurement precision, in the prior art, the work for improving the measurement precision of the gravity gradiometer mainly focuses on researching and compensating the angular motion error, the linear motion error, the self-gradient and the vertical motion error in the working process of the gravity gradiometer, such as Chinese patents CN109212619B, CN109212629B, CN109212620B, CN110068876A and CN 108873093B; or the gravity gradiometer data is diagnosed and processed, and interference data such as CN110471123A is removed, so as to improve the measurement performance of the machine. However, in addition to the above influencing factors, it is important to accurately determine the demodulation phase angle of the gravity gradient, which directly influences the demodulation result of the gravity gradient, thereby influencing the gravity gradient measurement performance. Errors in the demodulated phase angle mainly come from the aspects of stability of the rotating mechanism, control stability of the motor, circuit noise, transmission delay caused by signal processing and the like. At present, no relevant literature is published or published for a gravity gradient demodulation phase angle determination method of a gravity gradiometer of a rotating accelerometer.

Disclosure of Invention

The invention has the following problems: in order to overcome the defects of the prior art, the invention provides the gravity gradient demodulation phase angle determination method and device of the gravity gradiometer, which are simple to operate, convenient to implement and high in practicability.

The technical scheme is as follows: in a first aspect, a method for determining a gravity gradient demodulation phase angle of a gravity gradiometer of a rotary accelerometer is provided, which includes the following steps:

carrying out signal combination conditioning on output signals of the four accelerometers to obtain gravity gradient analog signals;

the A/D converter performs A/D conversion on the gravity gradient analog signal according to the synchronous pulse signal sent by the angle information converter to obtain a gravity gradient digital signal;

and demodulating the phase angle of the gravity gradient digital signal by using a reference signal source to obtain a gravity gradient demodulation phase angle.

Wherein, the gravity gradient digital signal expression obtained by the A/D conversion is as follows:

in the formula, A_k、B_kAre the amplitudes of the 2k +1 th harmonic sine and cosine signals, C_k2k +2 harmonic signal amplitude, D is disc rotation angular acceleration amplitude, α is gravity gradient demodulation phase angle,to condition the delay angle caused by the delay of the path signal, φ is the first accelerometer A₁Initial angle between the gravity gradiometer and the x-axis of the gravity gradiometer coordinate system, theta is azimuth angle caused by environmental objects, delta t is sampling time, omega is the rotation angular frequency of the disk of the gravity gradiometer,

for angular acceleration of rotation of the disk of a gradiometer, E_out(i) Is a digital signal at the (i-1) th time delta t.

Further, the phase angle demodulation of the gravity gradient digital signal by using the reference signal source comprises:

generating a digital sine signal and a digital cosine signal as reference signals;

and 2, performing frequency multiplication amplitude demodulation on the output signal of the A/D converter by using the reference signal, and changing the initial phase angle of the reference signal until the maximum amplitude is obtained, wherein the initial phase angle at the moment is the gravity gradient demodulation phase angle.

Wherein, the calculation expression of the gravity gradient demodulation phase angle is as follows:

in the formula, N is the pulse number output by the information converter every time the disk rotates one angle,

ζ_ithe correction angles of the initial phase angles of the sine signal reference source and the cosine signal reference source at the ith time are respectively, the right side | max of the equation represents the initial phase angle of the sine signal reference source and the cosine signal reference source corresponding to the searched maximum value, S_s(k, i) is a digital sinusoidal signal, S_c(k, i) is a digital cosine signal,ζ_qand respectively demodulating phase angles for the gravity gradient obtained for the q-th time.

Preferably, the method further comprises: and carrying out zero-phase low-pass filtering processing on the gravity gradient demodulation phase angle obtained by demodulation, and carrying out average processing on the filtered data to obtain a final gravity gradient demodulation phase angle.

In a second aspect, there is provided a device for demodulating phase angle of gravity gradient of a gravity gradiometer of a rotary accelerometer, comprising:

the signal conditioning module is used for carrying out signal combination conditioning on the output signals of the four accelerometers to obtain gravity gradient analog signals;

the A/D conversion module is used for carrying out A/D conversion on the gravity gradient analog signal according to the synchronous pulse signal sent by the angle information module to obtain a gravity gradient digital signal;

the angle information module is used for sending out a synchronous pulse signal;

and the phase angle demodulation module is used for demodulating the phase angle of the gravity gradient digital signal by using the reference signal source to obtain a gravity gradient demodulation phase angle.

Has the advantages that: the method for determining the gravity gradient demodulation phase angle of the gravity gradiometer of the rotating accelerometer is provided for the first time from an actual measurement system, the accurate locking of the gravity gradient signal phase can be realized by adopting the method, the gravity gradient demodulation precision is improved, and the method has the characteristics of simplicity and convenience in operation, convenience in implementation, strong applicability and the like, has an important reference value for the accurate gradient measurement of the gravity gradient, and can provide an application reference for the gravity gradient measurement.

Drawings

FIG. 1 is a schematic diagram of the working principle of the gravity gradient demodulation phase angle determination method of the gravity gradiometer of the rotary accelerometer of the invention;

FIG. 2 is a waveform diagram comparing a gravity gradient demodulation phase angle before and after zero-phase filtering according to an embodiment of the present invention.

Detailed Description

The technical scheme of the invention is further explained by combining the attached drawings.

Fig. 1 is a schematic diagram of a method for determining a gravity gradient demodulation phase angle of a gravity gradiometer of a rotary accelerometer according to the present invention, and the method for determining a gravity gradient demodulation phase angle of a gravity gradiometer of a rotary accelerometer according to the present invention is described with reference to fig. 1, and the method includes the following steps:

1) establishing a gravity gradient measurement coordinate system of the gravity gradiometer as a northeast geographical coordinate system, and recording as oxyz, wherein an original point o is a measurement center of the gravity gradiometer;

2) the output signals of the four accelerometers are processed by signal conditioning to obtain an analog signal E_out(t), the angle information converter outputs the synchronous pulse signal to the A/D converter, the A/D converter performs A/D conversion on the analog signal to obtain the digital signal E at the (i-1) th time delta t_out(i) The expression is as follows:

in the formula, A_k、B_kAre the amplitudes of the 2k +1 th harmonic sine and cosine signals, C_k2k +2 harmonic signal amplitude, D is disc rotation angular acceleration amplitude, α is gravity gradient demodulation phase angle,to condition the delay angle caused by the delay of the path signal, φ is the first accelerometer A₁The initial angle between the gravity gradiometer and the x-axis of the gravity gradiometer coordinate system, theta is the azimuth angle caused by the environmental object, namely the angle between the connecting line of the gravity center of the environmental object to the gravity center of the gravity gradiometer and the x-axis, delta t is the sampling time, omega is the rotation angular frequency of the disk of the gravity gradiometer,the acceleration of the rotation angle of the disk of the gravity gradiometer is obtained;

3) the reference signal source digital sine and cosine signal is sent by the DSP, and the expression is as follows:

in the formula (I), the compound is shown in the specification,

ζ_jcorrecting angles of initial phase angles of sine and cosine signal reference sources at the jth time are respectively set;

4) the output signal of the A/D converter is subjected to 2-frequency multiplication amplitude demodulation by using a reference signal source digital sine and cosine signal, an initial phase angle is changed until the maximum amplitude is obtained, the initial phase angle at the moment is a gravity gradient demodulation phase angle, and the calculation expression is as follows:

in the formula, N is the pulse number output by the information converter every time the disk rotates one angle,ζ_ithe correction angles of the initial phase angles of the sine signal reference source and the cosine signal reference source at the ith time are respectively, the right side | max of the equation represents the initial phase angle of the sine signal reference source and the cosine signal reference source corresponding to the searched maximum value,

ζ_qrespectively demodulating phase angles for the gravity gradient obtained for the q times;

5) demodulating phase angle of obtained gravity gradientAnd ζ_qAre combined in such a way that the combination modes are connected in sequence, namely

And then filtering the combined data through a zero-phase low-pass filter, and finally performing average processing on the processed phase angles to finally obtain a gravity gradient demodulation phase angle α.

Based on the implementation steps of the method for demodulating the phase angle by the gravity gradient of the rotating acceleration gravity gradiometer, the effectiveness of the method is verified by an example. Setting the base line distance of the disc to be 1m, the scale factor of the accelerometer to be 32mA/g and the gravity acceleration to be 9.81m/s²The rotation period of the disc is 20s, the sampling rate is 2Hz, and the accelerometer A is arranged at the initial moment₁The included angle between the gravity gradient signal and the x axis is 0 degree, the azimuth angle caused by the environmental object is 0 degree, the gravity gradient signal is subjected to data acquisition and processing, the angle change step length is 0.01 degrees, and the demodulation phase angle result is shown in fig. 2. As can be seen from the figure, the gravity gradient demodulation phase angle is about-50.3 degrees, the demodulation phase angle before the zero-phase filtering processing has large fluctuation and the standard deviation is 0.14 degrees, the fluctuation range is reduced after the zero-phase filtering processing, the standard deviation is 0.046 degrees, and finally the mean value of the gravity gradient demodulation phase angle is-50.29 degrees. If the initial phase angle of 0 degrees is used as the gravity gradient demodulation phase angle, a large gravity gradient measurement error is caused, and the gravity gradient measurement accuracy is affected.

According to another embodiment of the present invention, there is provided a gravity gradient demodulation phase angle determination apparatus for a gravity gradiometer of a rotary accelerometer, including:

the signal conditioning module is used for performing signal combination conditioning on the output signals of the four accelerometers to obtain a gravity gradient analog signal, and optionally, the signal conditioning module adopts a signal conditioning circuit;

the A/D conversion module is used for carrying out A/D conversion on the gravity gradient analog signal according to the synchronous pulse signal sent by the angle information module to obtain a gravity gradient digital signal, and optionally, the A/D conversion module adopts an A/D converter;

an angle information module for sending out a synchronous pulse signal, optionally, the angle information module employs an angle information converter on a grating angle encoder;

and the phase angle demodulation module is used for demodulating the phase angle of the gravity gradient digital signal by using a reference signal source to obtain a gravity gradient demodulation phase angle, and optionally, the phase angle demodulation module adopts a DSP.

Wherein, the gravity gradient digital signal expression output by the A/D converter is as follows:

in the formula, A_k、B_kAre the amplitudes of the 2k +1 th harmonic sine and cosine signals, C_k2k +2 harmonic signal amplitude, D is disc rotation angular acceleration amplitude, α is gravity gradient demodulation phase angle,

to condition the delay angle caused by the delay of the path signal, φ is the first accelerometer A₁Initial angle between the gravity gradiometer and the x-axis of the gravity gradiometer coordinate system, theta is azimuth angle caused by environmental objects, delta t is sampling time, omega is the rotation angular frequency of the disk of the gravity gradiometer,

for angular acceleration of rotation of the disk of a gradiometer, E_out(i) Is a digital signal at the (i-1) th time delta t.

The phase angle demodulation module includes: a reference signal generating unit for generating a digital sine signal and a digital cosine signal as reference signals;

and the calculating unit is configured to perform 2-frequency multiplication amplitude demodulation on the output signal of the A/D converter by using the reference signal, and change an initial phase angle of the reference signal until the maximum amplitude is obtained, wherein the initial phase angle is a gravity gradient demodulation phase angle, and a calculation expression of the gravity gradient demodulation phase angle is as follows:

in the formula, N is the pulse number output by the information converter every time the disk rotates one angle,ζ_ithe correction angles of the initial phase angles of the sine signal reference source and the cosine signal reference source at the ith time are respectively, the right side | max of the equation represents the initial phase angle of the sine signal reference source and the cosine signal reference source corresponding to the searched maximum value,

ζ_qand respectively demodulating phase angles for the gravity gradient obtained for the q-th time.

In a preferred embodiment, the gravity gradient demodulation phase angle determination apparatus further includes a phase angle optimization module for demodulating the phase angle of the obtained gravity gradient

And ζ_qAre combined and sequentially connected to obtain

And then carrying out zero-phase low-pass filtering processing on the combined data, and carrying out mean processing on the filtered data to obtain a final gravity gradient demodulation phase angle.

The above examples are only preferred embodiments of the present invention, it should be noted that: it will be apparent to those skilled in the art that various modifications and equivalents can be made without departing from the spirit of the invention, and it is intended that all such modifications and equivalents fall within the scope of the invention as defined in the claims.