阅读说明：本技术 一种适用于旋转炮弹的动态环路跟踪方法及装置 (Dynamic loop tracking method and device suitable for rotary cannonball ) 是由 王勋 孟为茹 韩舒文 孙艺宁 高亚豪 洪诗聘 祖秉法 庄树峰 刘璞 于 2021-08-11 设计创作，主要内容包括：本发明公开了一种适用于旋转炮弹的动态环路跟踪方法及装置。本发明在接收机环路中增加转速估计单元,并利用环路跟踪原始信息进行卡尔曼滤波,获得卫星入射方向的俯仰角和方位角,再结合在地面估计出的相位中心偏差,计算得到因天线相位中心偏差导致的多普勒误差估计值,补偿到跟踪环路的码频率和载波频率中,以实现对旋转调制的误差补偿。本发明地面可操作性强,算法应用简单,无复杂或运算量巨大的算式,实时性和运算量方面都可保证在DSP或FPGA硬件平台上的算法编程实现,即易于工程实现。(The invention discloses a dynamic loop tracking method and a dynamic loop tracking device suitable for a rotary cannonball. The invention adds a rotating speed estimation unit in a receiver loop, utilizes the original information of loop tracking to carry out Kalman filtering to obtain the pitch angle and the azimuth angle of the incident direction of a satellite, then combines the phase center deviation estimated on the ground to calculate and obtain a Doppler error estimated value caused by the phase center deviation of an antenna, and compensates the Doppler error estimated value into the code frequency and the carrier frequency of a tracking loop so as to realize the error compensation of rotating modulation. The method has the advantages of strong ground operability, simple algorithm application, no complex or huge calculation formula, and capability of ensuring the realization of algorithm programming on a DSP or FPGA hardware platform in real time and calculation amount, namely the method is easy to realize in engineering.)

1. A method of dynamic loop tracking for a rotating projectile, comprising the steps of:

step 1, constructing a deviation excitation and reference pseudo range environment, and performing amplitude estimation on error output under a fixed pitch angle to realize estimation of the deviation of the phase center of the cannonball antenna on the ground;

step 2, acquiring an estimated value of the rotating speed of the projectile body in a short time;

step 3, calculating a Doppler error estimated value by using a pitch angle and an azimuth angle of the satellite incidence direction solved by Kalman filtering and combining phase center deviation estimated on the ground and a projectile body rotating speed value;

and 4, compensating the Doppler error estimated value obtained in the step 3 into the code frequency and the carrier frequency of the tracking loop to realize error compensation of the rotary modulation.

2. The method of claim 1, wherein the method of estimating the deviation of the phase center of the projectile antenna in step 1 comprises:

fixing the antenna of the rotary shell receiver at a calibrated reference point along with the rotary tool;

after the satellite receiver stably receives and positions the satellite, starting the tool to rotate, keeping the antenna at the calibrated reference point for no more than 2 minutes, and acquiring the azimuth psi of each satellite participating in positioning_iAnd a pitch angle theta_iObtaining the range error Delta L of each satellite_i；

Range error Δ L for each acquired satellite_iAmplitude detection, extremum processing, and averagingAnd root mean square l_rmsIf root mean square l_rmsLess than threshold l_thredThen, the bias excitation is considered to be effective, and effective bias extraction is performed, that is, effective bias is extracted asOtherwise, the deviation excitation is considered to fail, and the extraction is not carried out.

3. The dynamic loop tracking method for the rotary projectile as claimed in claim 1, wherein said step 2 is implemented by performing a sliding FFT spectrum analysis on the discrete digital values outputted from the integral accumulation of the I branch of the tracking loop to obtain the frequency in a short time, i.e. the rotation speed n.

4. The dynamic loop tracking method of claim 3, wherein the sliding time window is between 4ms and 10 ms.

5. A method of dynamic loop tracking for a rotating projectile as claimed in claim 1, wherein said doppler error estimates of step 3 are:

in the formula I₀And n is the offset of the phase center of the antenna, n is the rotation speed of the projectile body, psi is the initial azimuth angle of the satellite incident signal, and theta is the pitch angle of the satellite incident signal.

6. The method of claim 1, wherein the step 4 is performed on the doppler error compensation value Δ f_dAmplitude limiting processing before compensation is carried out, the Doppler error compensation processing of a code tracking loop and a carrier tracking loop is carried out only if the amplitude of the Doppler error is not more than a limit threshold,

the amplitude limiting principle of the clipping process is: 1) the rotating speed is 1.2 times of the theoretical maximum rotating speed; 2) the maximum offset of the antenna phase center is 5 per mill of the projectile diameter; 3) the satellite signal carrier frequency is the satellite carrier frequency actually used.

7. A dynamic loop tracking device suitable for rotating cannonball is characterized in that the tracking device comprises a phase center deviation estimation module, a cannonball rotating speed estimation module, a Doppler error estimation module and an error compensation module,

the phase center deviation estimation module carries out amplitude estimation on error output under a fixed pitch angle based on constructed deviation excitation and a reference pseudo range environment, so that the estimation of the deviation of the phase center of the cannonball antenna on the ground is realized;

the projectile body rotating speed estimation module is used for acquiring a projectile body rotating speed estimation value in a short time;

the Doppler error estimation module calculates a Doppler error estimation value by utilizing a pitch angle and an azimuth angle of the satellite incidence direction solved by Kalman filtering and combining phase center deviation estimated on the ground and a projectile body rotating speed value;

the error compensation module compensates the obtained Doppler error estimated value to the code frequency and the carrier frequency of the tracking loop to realize error compensation of rotary modulation.

8. The dynamic loop tracking apparatus for a rotating projectile of claim 7, wherein the method of estimating the deviation of the phase center of the projectile antenna in the phase center deviation estimation module is as follows:

fixing the antenna of the rotary shell receiver at a calibrated reference point along with the rotary tool;

after the satellite receiver stably receives and positions the satellite, starting the tool to rotate, keeping the antenna at the calibrated reference point for no more than 2 minutes, and acquiring the azimuth psi of each satellite participating in positioning_iAnd a pitch angle theta_iObtaining the range error Delta L of each satellite_i；

Range error Δ L for each acquired satellite_iAmplitude detection, extremum processing, and averagingAnd root mean square l_rmsIf root mean square l_rmsLess than threshold l_thredThen, the bias excitation is considered to be effective, and effective bias extraction is performed, that is, effective bias is extracted asOtherwise, the deviation excitation is considered to fail, and the extraction is not carried out.

9. The dynamic loop tracking device for the rotary projectile as claimed in claim 7, wherein the sliding FFT spectral analysis is performed on the discrete digital quantity output by the integral accumulation of the I branch of the tracking loop to obtain the frequency in a short time, i.e. the rotation speed n, and the value of the sliding time window is 4ms to 10 ms.

10. The dynamic loop tracking apparatus for a rotating projectile of claim 7 wherein said error compensation module compensates for a doppler error compensation value Δ f_dAmplitude limiting processing before compensation is carried out, the Doppler error compensation processing of a code tracking loop and a carrier tracking loop is carried out only if the amplitude of the Doppler error is not more than a limit threshold,

the amplitude limiting principle of the clipping process is: 1) the rotating speed is 1.2 times of the theoretical maximum rotating speed; 2) the maximum offset of the antenna phase center is 5 per mill of the projectile diameter; 3) the satellite signal carrier frequency is the satellite carrier frequency actually used.

Technical Field

The invention belongs to the field of satellite navigation information processing, and relates to a dynamic loop tracking method of a satellite navigation receiver suitable for a rotary projectile.

Background

Satellite navigation receivers have become a popular navigation device for rotating projectiles due to their small size and low cost. During the flying process of the cannonball, the superposition of the axial motion and the tangential motion of the cannonball body exists. When the traditional satellite navigation receiver is applied to cannonballs, a plurality of problems are faced, and the main problems are as follows: 1) signal occlusion problems caused by projectile rotation; 2) tangential motion caused by rotation causes a speed measurement error problem; 3) dynamic adaptability problem during rotation; 4) the effect of rotational modulation on the phase of the signal.

At present, the main technical means for solving the problems 1) to 2) is a dual-antenna synthesis method, that is, two conformal antennas symmetrically installed on the surface of a projectile body are combined to form an omnidirectional directional pattern perpendicular to the projectile axis, so that the satellite receiving of the antennas is not influenced by rotation. Meanwhile, two conformal antenna units are fed in parallel, so that the antenna phase center is designed on the elastic shaft, and tangential motion is theoretically eliminated. The main method for solving the problem 3) is to adopt a frequency locking ring to assist the design of a phase-locked loop, adapt to high dynamic performance by adjusting the bandwidth parameter of a filter, or comprehensively regard the error of the rotation modulation effect as noise and adopt a pure frequency locking ring design. The former can overcome the loop lock loss caused by large axial dynamic, and simultaneously ensures certain tracking precision, but the former is easily influenced by the rotating speed of the projectile body, and the loop stability and adaptability are poor; the latter loop has simple structure, better dynamic adaptability and poorer tracking precision. The main method for solving the problem 4) is to predict the rotating speed of the projectile body through a geomagnetic sensor or single-antenna star collection and carry out error compensation of a rotation modulation effect, but the geomagnetic measurement has more using and restricting factors, the using and maintaining process is complex, the single-antenna star collection rotating speed estimation algorithm is complex, and the restriction conditions are more.

Aiming at the application scene of the rotating high dynamic projectile body, the four problems need to be solved simultaneously so as to improve the loop tracking stability and the tracking precision.

Disclosure of Invention

The invention aims to provide a method and a device for tracking a dynamic loop of a satellite navigation receiver, which have good tracking stability and high speed measurement precision and are suitable for rotating shells.

In order to solve the technical problem, the invention provides a dynamic loop tracking method suitable for a rotary cannonball, which adopts the technical scheme that the method comprises the following steps:

step 1, constructing a deviation excitation and reference pseudo range environment, and performing amplitude estimation on error output under a fixed pitch angle to realize estimation of the deviation of the phase center of the cannonball antenna on the ground;

step 2, acquiring an estimated value of the rotating speed of the projectile body in a short time;

step 3, calculating a Doppler error estimated value by combining the phase center deviation estimated on the ground, the projectile body rotating speed value, and the pitch angle and the azimuth angle of the satellite incident direction;

and 4, compensating the Doppler error estimated value obtained in the step 3 into the code frequency and the carrier frequency of the tracking loop to realize error compensation of the rotary modulation.

According to another aspect of the invention, a dynamic loop tracking device suitable for a rotary shell is provided, which adopts the following technical scheme:

the tracking device comprises a phase center deviation estimation module, a projectile body rotating speed estimation module, a Doppler error estimation module and an error compensation module.

The phase center deviation estimation module carries out amplitude estimation on error output under a fixed pitch angle based on constructed deviation excitation and a reference pseudo range environment, so that the estimation of the deviation of the phase center of the cannonball antenna on the ground is realized;

the projectile body rotating speed estimation module is used for acquiring a projectile body rotating speed estimation value in a short time;

the Doppler error estimation module calculates a Doppler error estimation value by utilizing a pitch angle and an azimuth angle of the satellite incidence direction solved by Kalman filtering and combining phase center deviation estimated on the ground and a projectile body rotating speed value;

the error compensation module compensates the obtained Doppler error estimated value to the code frequency and the carrier frequency of the tracking loop to realize error compensation of rotary modulation.

The technical scheme of the invention is that the amplitude estimation is carried out on the error output under the fixed pitch angle through artificially constructing a deviation excitation condition and a reference pseudo-range condition, thereby realizing the estimation of the deviation of the cannonball antenna phase center on the ground; under the premise of knowing the deviation of the antenna phase center, the output of a carrier phase discriminator and a code phase discriminator is used as the measurement of a Kalman filter, the position, the speed and the ephemeris of a receiver are used as the carrier and code NCO prediction, and the pitch angle and the azimuth angle of the satellite incident direction are calculated after filtering. Meanwhile, a projectile body rotating speed estimation module is constructed, phase center deviation estimated on the ground is combined, and a rotating speed estimation value and a pitch angle and an azimuth angle of an incident direction of a satellite are combined, so that a Doppler error estimation value caused by the antenna phase center deviation is calculated and used for compensating a Doppler measurement value, Doppler frequency errors caused by rotation are effectively eliminated, stable tracking of a dynamic loop of a receiver is realized, and speed measurement accuracy of the receiver under a rotating condition is improved.

The method has the advantages that the Doppler error is obtained by utilizing the relation between the rotation modulation error caused by the deviation of the antenna phase center and the incident pitch angle and the azimuth angle of the satellite signal and adopting the mode of ground phase center deviation estimation, the Doppler error is compensated into a tracking loop, and the problem of large speed measurement error during rotation can be solved. Innovatively providing a method for estimating the amplitude of error output under a fixed pitch angle by constructing a deviation excitation condition and a reference pseudo-range condition so as to further realize the estimation of the phase center of an antenna on the ground; a method for solving the satellite signal incidence angle by adopting the original loop parameters and performing loop compensation on the calculated Doppler error by combining projectile body rotating speed estimation is innovatively provided, the method for performing general tracking by adopting a pure frequency-locked loop is fundamentally broken through, and the tracking precision of the frequency-locked loop auxiliary phase-locked loop is effectively improved.

According to the method, Kalman filtering is performed by using original information of a loop and information such as ephemeris and position, Doppler is calculated by using information such as an incident angle, an estimated rotating speed and phase center deviation estimated on the ground, which are calculated by filtering, and loop compensation is performed. The method has the advantages of strong ground operability, simple algorithm application, no complex or huge calculation formula, and capability of ensuring the realization of algorithm programming on a DSP or FPGA hardware platform in real time and calculation amount, namely, the method is easy to realize in engineering.

Drawings

FIG. 1 is a schematic block diagram of a method for dynamic loop tracking of a satellite navigation receiver adapted for rotating projectiles according to the present invention;

FIG. 2 is a schematic diagram of a projectile rotation motion coordinate system;

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 is a schematic block diagram of a method for dynamic loop tracking of a satellite navigation receiver for rotating projectiles in accordance with the teachings of the present invention. In fig. 1, a doppler error estimation step caused by rotation modulation is introduced, so that the loop performs doppler error correction, which is implemented in two stages, namely a ground deviation estimation stage and a flight real-time correction stage. The specific method comprises the following steps:

in the ground deviation estimation stage, under the condition that the pseudo-range reference is known, the deviation l of the phase center of the projectile antenna is estimated by using a deviation excitation method₀An estimate is made to provide parameter elements for flight real-time corrections. The antenna phase center deviation is mainly caused by mounting errors, mounting surface tolerances, antenna design and manufacturing errors, time-dependent material deformation errors and the like, wherein the mounting errors, the mounting surface tolerances, the antenna design and manufacturing errors and the like account for most of the antenna phase center deviation, and the time-dependent material deformation errors are related to the antenna phase center deviation. Therefore, for convenient maintenance and use, the deviation estimation at the ground stage can be carried out only once after the cannonball leaves the factory, and whether the cannonball needs to be carried out again or not can be flexibly determined according to the storage time of the cannonball.

The real-time flight correction stage comprises the pitch angle theta, the azimuth angle psi and the projectile body of the satellite incident signal which are calculated by Kalman filteringEstimated value of rotating speed n, and phase center deviation l estimated by combining the estimated value on the ground₀Thereby calculating the Doppler error estimated value delta f caused by the deviation of the antenna phase center_d. Will Doppler error Δ f_dAnd the frequency error compensation of the rotation modulation is realized by introducing the frequency error compensation into a code NCO and a carrier NCO of a tracking loop.

In an embodiment of the present invention, the ground estimation of the antenna phase center deviation includes the following steps:

step S1, bias excitation and reference pseudo range environment construction

Fixing the antenna of the rotary shell receiver at a calibrated reference point along with a rotary tool, and calculating to obtain a reference pseudo-range by using a three-dimensional position and a reference point three-dimensional coordinate of a certain satellite (with the number of i) after the satellite receiver stably receives the satellite and positions the satellite receiverSetting the measured pseudo range asThe distance measurement error can be obtainedInitial azimuth psi of the satellite incident signal in a short time_iAnd a pitch angle theta_iThe variation is not large and can be considered as a known constant value.

Step S2, deviation excitation

And starting the tool to rotate, and keeping the antenna at the calibrated reference point, so that the antenna of the rotary cannonball receiver rotates along with the rotary tool, and the time is not more than 2 minutes. Acquiring the azimuth psi of each participating positioning satellite (the total number of the participating positioning satellites is M)_iAnd a pitch angle theta_iObtaining the range error Delta L of each satellite_iUsing the range error DeltaL of the tool for each acquired satellite_iCarrying out amplitude detection to obtain amplitude

Step S3, extracting effective deviation of antenna phase center

For M amplitude measured values obtained by detectionAfter extremum processing (removal of maxima and minima), the remaining (M-2) amplitude measurements are averagedAnd root mean square l_rms。

If root mean square l_rmsLess than threshold l_thredThen the bias excitation is considered to be effective, and effective bias extraction can be performed, that is, effective bias is extracted asOtherwise, the bias excitation is considered to fail, and the extraction cannot be performed. The bias excitation step may be performed again.

In an embodiment provided by the present invention, the projectile rotation speed estimation method includes:

as shown in fig. 1, the integral accumulation output of the branch I of the tracking loop is utilized, and fft (fast Fourier transform) spectrum analysis is performed on the output discrete digital quantity to obtain the frequency in a short time, i.e. the rotation speed n. Because the rotating speed of the projectile body is not changed greatly, sliding FFT is carried out on the I branch information so as to update the rotating speed in real time.

The value of the sliding time window is determined according to the rotating speed characteristics of different cannonball types, and the type with small rotating speed change is 4-10 ms.

In an embodiment provided by the present invention, the method for estimating the incident angle of the satellite signal comprises:

constructing Kalman filtering, acquiring ephemeris, time and synchronization parameters after signal tracking synchronization, and acquiring a satellite position p after calculation_satVelocity v_satIt is input to the kalman filter as a prediction. Satellite pseudo range rho and pseudo range rate output by using carrier phase discriminator and code phase discriminatorAs a measure of the kalman filter. And calculating the local position of the receiver after filtering, and obtaining the azimuth angle psi and the pitch angle theta in the incident direction of the satellite by using the local position and the satellite position.

In an embodiment provided by the present invention, the doppler error compensation value calculating method includes:

as shown in fig. 2, the estimated distance measurement error of the rotation modulation of the rotating projectile due to the antenna phase center is:

ΔL＝l₀ cos(2πnt+ψ)cos(θ)+Δξ (1)

in the formula I₀The offset of the antenna phase center is shown, n is the rotation speed of the projectile body, psi is the initial azimuth angle of the satellite incident signal, theta is the pitch angle of the satellite incident signal, and delta xi is the ranging error caused by the phase center variation, which is the random error related to the azimuth angle of the projectile body, the pitch angle and the satellite signal carrier frequency.

For equation (1), the distance measurement change rate error of the rotation modulation of the rotary projectile caused by the change of the antenna phase center can be obtained by differentiating Δ L with respect to time t:

ΔV＝-2πnl₀ sin(2πnt+ψ)cos(θ)+Δξ/Δt (2)

in the formula I₀And n is the offset of the phase center of the antenna, n is the rotation speed of the projectile body, psi is the initial azimuth angle of the satellite incident signal, and theta is the pitch angle of the satellite incident signal.

In the formula (2), Δ ξ/Δ t is a distance measurement change rate error caused by the phase center change amount, and the error term can be ignored in engineering application. Converting equation (2) to a Doppler error of

Where C is the speed of light and f is the carrier frequency of the satellite signal.

In an embodiment provided by the present invention, the method for loop compensation of doppler error includes:

using calculated Doppler error compensation value Δ f_dAnd performing Doppler error compensation on a code NCO and a carrier NCO of the tracking loop. In practical applications, it is considered that loop stability tracking is preferred to velocity measurement error compensation, and therefore, the doppler error compensation value Δ f needs to be set_dAnd performing amplitude limiting processing before compensation.

The amplitude limiting principle of the clipping process is: 1) the rotating speed is 1.2 times of the theoretical maximum rotating speed; 2) the maximum offset of the antenna phase center is 5 per mill of the projectile diameter; 3) the satellite signal carrier frequency is the satellite carrier frequency actually used.

According to the principle, assuming that the diameter of the cannonball is R and the theoretical maximum rotating speed is P revolutions per second, the amplitude limiting threshold of the Doppler error which is not easy to obtain is defined as

Therefore, in practical applications, if the Doppler error compensation value Δ f is used_dGreater than a thresholdError compensation processing is not performed; if not greater than the thresholdThe Doppler error compensation processing of the code tracking loop and the carrier tracking loop is carried out to improve the speed measurement precision during rotation.

According to a further aspect of the invention there is provided a dynamic loop tracking apparatus suitable for use with a rotating projectile, embodied as follows:

the tracking device comprises a phase center deviation estimation module, a projectile body rotating speed estimation module, a Doppler error estimation module and an error compensation module.

The phase center deviation estimation module carries out amplitude estimation on error output under a fixed pitch angle based on constructed deviation excitation and a reference pseudo range environment, so that the estimation of the deviation of the phase center of the cannonball antenna on the ground is realized;

the projectile body rotating speed estimation module is used for acquiring a projectile body rotating speed estimation value in a short time;

the Doppler error estimation module calculates a Doppler error estimation value by utilizing a pitch angle and an azimuth angle of the satellite incidence direction solved by Kalman filtering and combining phase center deviation estimated on the ground and a projectile body rotating speed value;

the error compensation module compensates the obtained Doppler error estimated value to the code frequency and the carrier frequency of the tracking loop to realize error compensation of rotary modulation.

In an embodiment provided by the present invention, the method for estimating the deviation of the phase center of the shot antenna in the phase center deviation estimation module is as follows:

fixing the antenna of the rotary shell receiver at a calibrated reference point along with the rotary tool;

after the satellite receiver stably receives and positions the satellite, starting the tool to rotate, keeping the antenna at the calibrated reference point for no more than 2 minutes, and acquiring the azimuth psi of each satellite participating in positioning_iAnd a pitch angle theta_iObtaining the range error Delta L of each satellite_i；

Range error Δ L for each acquired satellite_iAmplitude detection, extremum processing, and averagingAnd root mean square l_rmsIf root mean square l_rmsLess than threshold l_thredThen, the bias excitation is considered to be effective, and effective bias extraction is performed, that is, effective bias is extracted asOtherwise, the deviation excitation is considered to fail, and the extraction is not carried out.

In an embodiment provided by the present invention, in the projectile rotation speed estimation module, a sliding FFT spectrum analysis is performed on a discrete digital quantity output by integral accumulation of the tracking loop I branch, so as to obtain a frequency within a short time, that is, a rotation speed n.

Further, the sliding time window takes a value of 4ms to 10 ms.

In an embodiment provided by the present invention, the doppler error estimation value in the doppler error estimation module is:

in the formula I₀And n is the offset of the phase center of the antenna, n is the rotation speed of the projectile body, psi is the initial azimuth angle of the satellite incident signal, and theta is the pitch angle of the satellite incident signal.

In an embodiment of the present invention, the error compensation module compensates the doppler error by the compensation value Δ f_dAnd carrying out amplitude limiting processing before compensation, and carrying out Doppler error compensation processing on the code tracking loop and the carrier tracking loop only if the amplitude of the Doppler error is not greater than a limit threshold.

The amplitude limiting principle of the clipping process is: 1) the rotating speed is 1.2 times of the theoretical maximum rotating speed; 2) the maximum offset of the antenna phase center is 5 per mill of the projectile diameter; 3) the satellite signal carrier frequency is the satellite carrier frequency actually used.

The embodiment of the dynamic loop tracking device for a rotary projectile according to the present invention can be specifically used for executing the processing procedure of the embodiment of the dynamic loop tracking method for a rotary projectile in the above embodiments, and the functions thereof are not described again.

The present invention has been described in terms of the preferred embodiment, and it is not limited thereto, but various modifications and changes will be apparent to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.