A laboratory evaluation method and system for the stellar vector observation accuracy of star sensors

Abstract

A laboratory assessment method for the stellar vector observation accuracy of a star sensor includes: establishing a star sensor calibration and accuracy assessment system, jointly modeling and calibrating the star sensor's intrinsic and extrinsic parameters to obtain calibration results; statically or dynamically rotating a turntable to collect data at certain angles or time intervals; converting the imaged star point coordinates in the collected data into star sensor observation vectors based on the calibrated intrinsic and extrinsic star sensor parameters and the corresponding lens distortion model and pinhole imaging model; and uniformly linearly transforming the star sensor observation vectors to the turntable's initial position coordinate system to obtain the observation vectors; estimating the concentration parameter of the obtained observation vectors; and converting the concentration parameter into the standard deviation parameter of a normal distribution to obtain the star sensor's stellar vector observation accuracy. This method can more accurately estimate the stellar vector observation accuracy of a star sensor, requires no changes to the existing system, and simplifies calculations.

Description

Technical Field

[0001] The present invention relates to the technical field of star sensors, and in particular to a laboratory evaluation method and system for star sensor stellar vector observation accuracy. Background Art

[0002] A star sensor is an optoelectronic navigation instrument used for three-axis attitude measurement. By observing star vectors and using a navigation star catalog as a reference, it can autonomously identify and track star patterns. Based on the identification / tracking results, it uses a multi-vector attitude determination algorithm to calculate high-precision three-axis attitude information in real time. As the most accurate attitude measurement device currently available, star sensors are widely used in a variety of navigation vehicles, including missiles, rockets, satellites, ships, and instruments.

[0003] Currently, high-precision star sensor calibration often utilizes a method based on the joint modeling of intrinsic parameters (principal point, focal length, and distortion coefficient) and extrinsic parameters (star model vector direction and mounting matrix) within the "optical platform - single star simulator - high-precision turntable - measurement and control computer - star sensor product" system. (See invention patent CN200510112553.7.) After calibrating these intrinsic and extrinsic parameters, the stellar vector observation accuracy (static and dynamic) must be assessed under laboratory conditions. This assessment is a crucial reference for the boresight pointing accuracy of the star sensor product's performance indicators.

[0004] At present, the mainstream evaluation method for the star vector observation accuracy of star sensors is to reproject the star model vector onto the imaging plane of the star sensor product based on the above calibration results according to the turntable attitude at the data collection point and the internal and external parameters obtained by calibration, and then calculate the difference between the star model vector and the image point coordinates collected by the star sensor to obtain the pixel error. and , integrate all the collection points and calculate the standard deviation , and radial standard deviation , and then according to the angular resolution parameter of the star sensor Calculating vector observation accuracy .

[0005] Since the angular error of the observation vector is projected non-uniformly on the image plane according to the pinhole imaging model, the pixel error corresponding to the vector observation error at the edge of the star sensor field of view is and Compared to the center of the field of view, this will cause The estimated value of is too large; in addition, the error of the angular resolution parameter of the star sensor will also cause Therefore, a more reasonable method for estimating the accuracy of star sensor stellar vector observations is still needed. Summary of the Invention

[0006] To address the problem of inaccurate estimation of the stellar vector observation accuracy of existing star sensors, the present invention aims to provide a laboratory assessment method and system for the stellar vector observation accuracy of star sensors. The method of the present invention is a vector observation accuracy estimation method based on Fisher distribution. The method introduces a quasi-normal distribution on a three-dimensional sphere, the Fisher distribution, to more accurately estimate the parameters of the star sensor observation vector. Utilizing the equivalence between the Fisher distribution and the two-dimensional normal distribution under high concentration conditions, the Fisher distribution parameters are converted into more intuitive normal distribution parameters, thereby accurately estimating the star sensor vector observation accuracy.

[0007] The present invention is achieved by the following technical solutions:

[0008] A first aspect of the present invention provides a laboratory evaluation method for the stellar vector observation accuracy of a star sensor, comprising the following steps:

[0009] Step S100: Building a star sensor calibration and accuracy assessment system, and performing joint modeling and calibration of the star sensor's intrinsic and extrinsic parameters to obtain a calibration result;

[0010] Step S200 , rotating the turntable in a static or dynamic manner, setting data collection points at certain angles or time intervals to collect data;

[0011] Step S300: Based on the star sensor internal and external parameters calibrated in step S100 and the corresponding lens distortion model and pinhole imaging model, the imaging star point coordinates in the data collected in step S200 are converted to Converted to star sensor observation vector , and then according to the star sensor installation matrix obtained by calibration in step S100 and the turntable posture matrix in the data collected in step S200 , the star sensor observation vector The observation vector is obtained by uniform linear transformation to the coordinate system of the initial position of the turntable ;

[0012] Step S400, the observation vector obtained in step S300 Estimate the concentration parameter of

[0013] Step S500 , converting the concentration parameter in step S400 into a standard deviation parameter of a normal distribution to obtain the star vector observation accuracy of the star sensor.

[0014] Furthermore, in step S200, the collected data includes the coordinates of the imaging star points of the single star simulator starlight on the star sensor image plane and the attitude matrix of the turntable relative to the initial position at the time of exposure of the star sensor. The collection points make the star point imaging spread all over the star sensor image plane.

[0015] Furthermore, in step S300, according to the internal parameters of the star sensor And external parameters and the corresponding lens distortion model and pinhole imaging model, the coordinates of the star points in the collected data Converted to star sensor observation vector The calculation formula is:

[0016]

[0017] in:

[0018]

[0019]

[0020] Further, according to the star sensor installation matrix obtained by calibration in step S100 and the turntable posture matrix collected in step S200 , the star sensor observation vector The unified linear transformation to the turntable initial position coordinate system is obtained The calculation formula is:

[0021]

[0022] Furthermore, the step S400 includes:

[0023] Step S410, calculate the observation vector The arithmetic mean of ;

[0024] Step S420, calculate the mean Length of mold ;

[0025] Step S430, according to Fisher concentration formula Calculate the observation vector concentration parameter .

[0026] Further, The arithmetic mean of The calculation formula is:

[0027]

[0028] Where n is the number of data collection points;

[0029] Length of mold The calculation formula is:

[0030]

[0031] Furthermore, vector concentration When , the probability density of the Fisher distribution on the three-dimensional sphere is equivalent to the two-dimensional isotropic normal distribution on the tangent plane at the desired point on the sphere.

[0032] The present invention also relates to a laboratory evaluation system for the star sensor stellar vector observation accuracy, comprising:

[0033] The calibration module is used to build a star sensor calibration and accuracy assessment system, and to perform joint modeling and calibration of the star sensor's internal and external parameters to obtain the calibration results;

[0034] The acquisition module is used to rotate the turntable in a static or dynamic manner and set data acquisition points at certain angles or time intervals to collect data;

[0035] The observation vector module is used to convert the imaging star point coordinates in the collected data into the star sensor coordinates according to the calibrated star sensor internal and external parameters and the corresponding lens distortion model and pinhole imaging model. Converted to star sensor observation vector , and then install the star sensor matrix based on the calibration and the turntable attitude matrix in the acquired data , the star sensor observation vector The observation vector is obtained by uniform linear transformation to the coordinate system of the initial position of the turntable ;

[0036] Concentration estimation module, used for the observation vector Estimate the concentration parameter of

[0037] The standard deviation parameter module is used to convert the concentration parameter into the standard deviation parameter of the normal distribution to obtain the star vector observation accuracy of the star sensor.

[0038] The present invention also relates to an electronic device, comprising:

[0039] at least one processor; and,

[0040] a memory communicatively connected to the at least one processor; wherein,

[0041] The memory stores instructions that are executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method.

[0042] The present invention also relates to a non-transitory computer-readable storage medium storing computer instructions for causing the computer to execute the method.

[0043] The technical solution of the present invention can achieve the following beneficial technical effects:

[0044] The present invention can more accurately estimate the star vector observation accuracy of the star sensor;

[0045] The present invention is not affected by the non-uniformity of pinhole imaging projection and the error of angular resolution parameters;

[0046] The present invention does not require changes to existing laboratory facilities and data collection content, and the calculation process is simpler.

[0047] The method of the present invention overcomes the influence of uneven pinhole imaging projection and angular resolution parameter error on existing estimation methods, can more accurately estimate the star sensor star vector observation accuracy, does not require changes to the existing system, and is simpler in calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a flow chart of the steps of the laboratory evaluation method of the star sensor star vector observation accuracy of the present invention;

[0049] Figure 2 This is a schematic diagram of the "optical platform - single star simulator - high-precision turntable - measurement and control computer - star sensor product" system required for the star sensor calibration and accuracy assessment of the present invention. Implementation Method

[0050] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0051] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0052] A first aspect of the present invention provides a laboratory evaluation method for the stellar vector observation accuracy of a star sensor. Specifically, the method of the present invention comprises the following steps:

[0053] Step S100: construct a star sensor calibration and accuracy assessment system, and perform joint modeling and calibration of the intrinsic and extrinsic parameters of the star sensor to obtain a calibration result.

[0054] The star sensor calibration and accuracy assessment system is an "optical platform - single star simulator - high-precision turntable - measurement and control computer - star sensor product" system.

[0055] Specifically, the unit vector of the starlight of the single star simulator in the coordinate system of the initial position of the turntable is The azimuth angle relative to the initial position of the turntable and pitch angle OK, the calculation formula is:

[0056] (1)

[0057] Specifically, the installation matrix of the star sensor coordinate system relative to the turntable coordinate system is By three-axis deflection , , OK, the calculation formula is:

[0058] (2)

[0059] Calibrated internal parameters of the star sensor and external parameters, where the star sensor principal point coordinates , focal length of star sensor , star sensor lens distortion coefficient .

[0060] Step S200: Rotate the turntable in a static or dynamic manner to set data collection points at certain angles or time intervals. The collected data includes the coordinates of the imaging star points of the star simulator starlight on the image plane of the star sensor. And the attitude matrix of the turntable relative to the initial position at the time of star sensor exposure , the collection points make the star point imaging spread all over the star sensor image surface.

[0061] Specifically, the turntable is divided into a two-axis turntable and a three-axis turntable.

[0062] The attitude matrix of the two-axis turntable relative to the initial position after rotation From the outer frame corner and the middle frame corner , determine, the calculation formula is:

[0063] (3.1)

[0064] The attitude matrix of the three-axis turntable relative to the initial position after rotation From the outer frame corner , middle frame corner , inner frame corner OK, the calculation formula is:

[0065] (3.2)

[0066] Step S300: calibrate the star sensor internal and external parameters obtained in step S100. As well as the corresponding lens distortion model and pinhole imaging model, the imaging star point coordinates in the data collected in step S200 are Converted to star sensor observation vector , and then according to the star sensor installation matrix obtained by calibration in step S100 and the turntable posture matrix in the data collected in step S200 , the star sensor observation vector The observation vector is obtained by uniform linear transformation to the coordinate system of the initial position of the turntable .

[0067] Specifically, according to the parameters of the star sensor As well as the lens distortion model and the pinhole imaging model, the star point coordinates Converted to star sensor observation vector The calculation formula is:

[0068] (4)

[0069] in:

[0070] (5)

[0071] (6)

[0072] Specifically, according to the star sensor installation matrix obtained by calibration in step S100 and the turntable posture matrix collected in step S200 , the star sensor observation vector The unified linear transformation to the turntable initial position coordinate system is obtained The calculation formula is:

[0073] (7)

[0074] Step S400: According to the mathematical properties of Fisher distribution, linear transformation of vector does not change its concentration parameter. The concentration parameter k is estimated.

[0075] Specifically, step S400 includes:

[0076] Step S410, calculate the observation vector The arithmetic mean of ;

[0077] Step S420, calculate the mean Length of mold ;

[0078] Step S430, according to Fisher concentration formula Calculate the observation vector concentration parameter .

[0079] Specifically, The arithmetic mean of The calculation formula is:

[0080] (8)

[0081] Where n is the number of data collection points.

[0082] Specifically, Length of mold The calculation formula is:

[0083] (9)

[0084] Specifically, the Fisher distribution concentration parameter and mold length The relationship is:

[0085] (10)

[0086] Its inverse function is when the concentration is high The formula is:

[0087] (11)

[0088] Step S500: Based on the higher concentration of vectors When the Fisher distribution is equivalent to the normal distribution, the concentration parameter of the Fisher distribution in step S400 is converted into the standard deviation parameter of the normal distribution to obtain the standard deviation parameter .

[0089] Specifically, when the vector concentration is high , the probability density of the Fisher distribution on the three-dimensional sphere is equivalent to the two-dimensional isotropic normal distribution on the tangent plane at the desired point on the sphere, and the standard deviation is:

[0090] (12)

[0091] Thus, an accurate estimate of the star sensor vector observation accuracy is obtained.

[0092] The present invention also relates to a laboratory evaluation system for the star sensor stellar vector observation accuracy, comprising:

[0093] The calibration module is used to build a star sensor calibration and accuracy assessment system, and to perform joint modeling and calibration of the star sensor's internal and external parameters to obtain the calibration results;

[0094] The acquisition module is used to rotate the turntable in a static or dynamic manner and set data acquisition points at certain angles or time intervals to collect data;

[0095] The observation vector module is used to convert the imaging star point coordinates in the collected data into the star sensor coordinates according to the calibrated star sensor internal and external parameters and the corresponding lens distortion model and pinhole imaging model. Converted to star sensor observation vector , and then install the star sensor matrix based on the calibration and the turntable attitude matrix in the acquired data , the star sensor observation vector The observation vector is obtained by uniform linear transformation to the coordinate system of the initial position of the turntable ;

[0096] Concentration estimation module, used for the observation vector The concentration parameter k is estimated;

[0097] The standard deviation parameter module is used to convert the concentration parameter into the standard deviation parameter of the normal distribution to obtain the standard deviation parameter .

[0098] The present invention also relates to an electronic device, comprising:

[0099] at least one processor; and,

[0100] a memory communicatively connected to the at least one processor; wherein,

[0101] The memory stores instructions that are executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method.

[0102] The present invention also relates to a non-transitory computer-readable storage medium storing computer instructions for causing the computer to execute the method.

[0103] In summary, the present invention provides a laboratory assessment method for the stellar vector observation accuracy of a star sensor, comprising the following steps: calibrating internal and external parameters on an "optical platform-single star simulator-high-precision turntable-measurement and control computer-star sensor product" system; statically or dynamically collecting observation vectors throughout the star sensor's field of view and the corresponding turntable attitudes; uniformly linearly transforming the observation vectors into the turntable's initial position coordinate system; and estimating the Fisher distribution concentration parameter of the observation vectors and converting them into a normal distribution standard deviation parameter.

[0104] It should be understood that the above-described specific embodiments of the present invention are merely illustrative or illustrative of the principles of the present invention and do not constitute limitations of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included within the scope of protection of the present invention. In addition, the appended claims are intended to cover all variations and modifications that fall within the scope and metes and bounds of the appended claims, or equivalents thereof.

Claims

1. A laboratory evaluation method for the accuracy of star sensor star vector observations, characterized in that: The steps include: Step S100: Building a star sensor calibration and accuracy assessment system, and performing joint modeling and calibration of the star sensor's intrinsic and extrinsic parameters to obtain a calibration result; Step S200 , rotating the turntable in a static or dynamic manner, setting data collection points at certain angles or time intervals to collect data; Step S300: Based on the star sensor internal and external parameters calibrated in step S100 and the corresponding lens distortion model and pinhole imaging model, the imaging star point coordinates in the data collected in step S200 are converted to Converted to star sensor observation vector , and then according to the star sensor installation matrix obtained by calibration in step S100 and the turntable posture matrix in the data collected in step S200 , the star sensor observation vector The observation vector is obtained by uniform linear transformation to the coordinate system of the initial position of the turntable ; Step S400, the observation vector obtained in step S300 Estimate the concentration parameter of Step S500 , converting the concentration parameter in step S400 into a standard deviation parameter of a normal distribution to obtain the star vector observation accuracy of the star sensor.

2. The laboratory evaluation method for star sensor stellar vector observation accuracy according to claim 1, characterized in that: In step S200, the collected data includes the coordinates of the imaging star points of the single star simulator starlight on the star sensor image plane and the attitude matrix of the turntable relative to the initial position at the time of exposure of the star sensor. The collected points make the star point imaging spread all over the star sensor image plane.

3. The laboratory evaluation method for star sensor stellar vector observation accuracy according to claim 1, characterized in that: In step S300, according to the internal parameters of the star sensor And external parameters and the corresponding lens distortion model and pinhole imaging model, the coordinates of the star points in the collected data Converted to star sensor observation vector The calculation formula is: ； in: ； 。 4. The laboratory evaluation method for star sensor stellar vector observation accuracy according to claim 3, characterized in that: According to the star sensor installation matrix obtained by calibration in step S100 and the turntable posture matrix collected in step S200 , the star sensor observation vector The unified linear transformation to the turntable initial position coordinate system is obtained The calculation formula is: 。 5. The laboratory evaluation method for star sensor stellar vector observation accuracy according to claim 1, characterized in that: The step S400 includes: Step S410, calculate the observation vector The arithmetic mean of ; Step S420, calculate the mean Length of mold ; Step S430, according to Fisher concentration formula Calculate the observation vector concentration parameter .

6. The laboratory evaluation method for star sensor stellar vector observation accuracy according to claim 5, characterized in that: The arithmetic mean of The calculation formula is: ； Where n is the number of data collection points; Length of mold The calculation formula is: 。 7. The laboratory evaluation method for star sensor stellar vector observation accuracy according to claim 1, characterized in that: Vector concentration When , the probability density of the Fisher distribution on the three-dimensional sphere is equivalent to the two-dimensional isotropic normal distribution on the tangent plane at the desired point on the sphere.

8. A laboratory evaluation system for the accuracy of star sensor star vector observations, characterized in that: include: The calibration module is used to build a star sensor calibration and accuracy assessment system, and to perform joint modeling and calibration of the star sensor's internal and external parameters to obtain the calibration results; The acquisition module is used to rotate the turntable in a static or dynamic manner and set data acquisition points at certain angles or time intervals to collect data; The observation vector module is used to convert the imaging star point coordinates in the collected data into the star sensor coordinates according to the calibrated star sensor internal and external parameters and the corresponding lens distortion model and pinhole imaging model. Converted to star sensor observation vector , and then install the star sensor matrix based on the calibration and the turntable attitude matrix in the acquired data , the star sensor observation vector The observation vector is obtained by uniform linear transformation to the coordinate system of the initial position of the turntable ; Concentration estimation module, used for the observation vector Estimate the concentration parameter of The standard deviation parameter module is used to convert the concentration parameter into the standard deviation parameter of the normal distribution to obtain the star vector observation accuracy of the star sensor.

9. An electronic device, characterized in that: The electronic device comprises: at least one processor; and, a memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method according to any one of the preceding claims 1 to 7. 10 . A non-transitory computer-readable storage medium storing computer instructions for causing a computer to execute the method according to claim 1 .

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