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CN-121978637-A - Weight model-based on-orbit calibration method for camera and radar photoelectric shaft

CN121978637ACN 121978637 ACN121978637 ACN 121978637ACN-121978637-A

Abstract

A weight model-based on-orbit calibration method for a camera and a radar photoelectric axis comprises the steps of enabling a camera optical axis to point to a target by controlling the attitude of a whole satellite, recording the position of the target under a camera system, determining the scanning range and the scanning step length of a radar, establishing a radar scanning coordinate system, determining radar scanning points, traversing scanning in the determined scanning range in a given scanning step length in sequence, sending radar beams to each scanning point by the radar, dividing virtual scattered points in a radar scanning area, determining the weight of each virtual scattered point in the scanning range according to the echo intensity and the position of the virtual scattered point, continuously updating the weight of each virtual scattered point in the radar scanning range according to the echo condition of the radar scanned each time, calculating the coordinate of the target under the radar scanning coordinate system according to the weight of each virtual scattered point, calculating the position of the target under the radar scanning system after the scanning is completed, determining the included angle between the camera optical axis and the radar photoelectric axis by combining the position of the target under the camera system, and calibrating the camera.

Inventors

  • HE JINGJING
  • LI RAN
  • WANG AIMING
  • ZENG HUASONG
  • HUANG KEYAN

Assignees

  • 北京空间飞行器总体设计部

Dates

Publication Date
20260505
Application Date
20251212

Claims (10)

  1. 1. The weight model-based on-orbit calibration method for the camera and the radar photoelectric shaft is characterized by comprising the following steps of: Selecting a target for calibration, controlling the attitude of the whole star to enable the optical axis of the camera to point to the target, and recording the position of the target under the camera system; Determining a radar scanning range and a scanning step length, establishing a radar scanning coordinate system, and determining radar scanning points; traversing and scanning the determined scanning range according to a set scanning step length in sequence, transmitting radar beams at each scanning point by using a radar, dividing a plurality of virtual scattered points in a radar scanning area, determining the weight of each virtual scattered point in the current scanning range according to the echo intensity and the positions of the virtual scattered points, and continuously updating the weight of each virtual scattered point in the radar scanning range according to the radar echo condition of each scanning; Calculating the coordinates of the target under a radar scanning coordinate system according to the weights of the virtual scattered points; After the scanning is completed, the position of the target under the radar scanning system is calculated, and the included angle between the optical axis of the camera and the electric axis of the radar is determined by combining the position of the target under the camera system, so that the calibration of the camera and the radar is completed.
  2. 2. The weight model-based on-orbit calibration method for cameras and radar photoelectric axes of claim 1, wherein the selection of targets is required to simultaneously satisfy: The target is positioned in the working distance range of the radar; the star of the target is superior to the detection sensitivity of the optical camera.
  3. 3. The weight model-based on-orbit calibration method for a camera and a radar photoelectric axis according to claim 1, wherein when determining a radar scanning range: Estimating the maximum amount theta max of the photoelectric axis deviation caused by the on-orbit force thermal condition, wherein the radar scanning range is not lower than 2 theta max ; The scanning step size is smaller than the radar half-beam width U.
  4. 4. The method for calibrating the photoelectric axis of the camera and the radar on the basis of the weight model in the on-orbit calibration method of the camera and the radar according to claim 1 is characterized in that the camera and the radar are in a linkage state, and when a radar scanning coordinate system is established: The camera optical axis points to the target, a radar scanning coordinate system is established at the position corresponding to the radar at the moment, and the direction of the current radar electric axis is taken as a scanning starting point.
  5. 5. The method for calibrating the camera and the radar photoelectric axis on-orbit based on the weight model according to claim 1 is characterized in that virtual scattered points are divided in a radar scanning area, and the method is specifically as follows: The position of the theoretical scanning point of the radar is S i when the ith scanning is performed under the radar scanning coordinate system, An index value indicating the number of scans is displayed, And is a positive integer of the number of the components, Representing the total scan number; the virtual scatter point P j is obtained by dividing the radar scanning area by a step de, Index values representing virtual scattered points in a certain area around S i , And is a positive integer of the number of the components, Representing the total number of virtual scattered points in the radar scanning area.
  6. 6. The weight model-based on-orbit calibration method for cameras and radar photoelectric axes, as set forth in claim 5, is characterized in that: when the weight of each virtual scattered point under the current scanning position is determined according to the echo intensity: if the radar echo signal-to-noise ratio is greater than the target detection signal-to-noise ratio, the weight W i (j) of each virtual scattered point in the ith scanning is as follows: W i (j)= w f j +(1-w) g j If the radar echo is not received or the echo signal-to-noise ratio is lower than the target detection signal-to-noise ratio, the weight of each virtual scattered point in the ith scanning is as follows: W i (j)= u f j +(1-u) g j w represents radar false alarm probability, u represents target detection probability, and f j 、g j represents a first basic weight and a second basic weight of each virtual scattered point determined according to echo intensity.
  7. 7. The method for on-orbit calibration of camera and radar photoelectric axis based on weight model as claimed in claim 6, wherein 2n+1 regions are set with scanning point S i as center of circle when determining first basic weight f j , n=floor (e max /de), floor [ ) Representing a downward rounding; When the position of the virtual scatter point P j satisfies: The first basis weight f j is: When the position of the virtual scatter point P j satisfies: wherein k=2 to 2n and is an integer, and the first basis weight f j is: When the scatter point P j is located outside the scan range area 1 to 2n, the first basic weight f j is: f j = ε Wherein epsilon represents a minimum value less than 10 -4 , F # ) Representing the cumulative distribution function of the satellite pointing error e, e max representing the 3σ or maximum value of the satellite pointing error e, dis (S i , P j ) representing the angle between S i and the line of the satellite, P j and the line of the satellite.
  8. 8. The method for on-orbit calibration of camera and radar photoelectric axis based on weight model as claimed in claim 6, wherein 2n+1 regions are set with scanning point S i as center of circle when determining second basic weight g j , n=floor (e max /de), floor [ ) Representing a downward rounding; When the position of the virtual scatter point P j satisfies: The second basis weight g j is: When the position of the virtual scatter point P j satisfies: Wherein k=2 to 2n and is an integer, and the second basic weight g j is: When the scatter point P j is located outside the scan range area 1 to 2n, the second basic weight g j is: g j = ε Wherein epsilon represents a minimum value less than 10 -4 , F # ) Representing the cumulative distribution function of the attitude pointing error e, e max representing the radar pointing error 3σ or maximum, dis (S i , P j ) representing the angle between the line of scan point S i and the satellite, and the line of virtual scatter point P j and the satellite.
  9. 9. The method for calibrating the camera and the radar photoelectric axis on-orbit based on the weight model according to claim 6, wherein the method is characterized in that the method comprises the steps of integrating a plurality of scanning results and updating the weight of each scattered point in the radar scanning range, and is specifically as follows: W i (j) represents the weight of the jth virtual scatter obtained by the ith scan, and W I (j) represents the weight of the jth virtual scatter after integrating the results of the 1 st, 2 nd.
  10. 10. The method for calibrating the camera and the radar photoelectric axis on-orbit based on the weight model according to claim 9, wherein the method is characterized in that the positions and the weights of the virtual scattered points are weighted, and the positions T l of the targets under the radar scanning system are estimated: W I (j) represents the j-th scatter weight after integrating the 1 st, 2 nd, I-th scan results.

Description

Weight model-based on-orbit calibration method for camera and radar photoelectric shaft Technical Field The invention relates to an on-orbit calibration method for a camera and a radar photoelectric shaft based on a weight model, in particular to an on-orbit calibration method for a satellite-borne radar and an optical camera without a goniometer function based on the weight model, and belongs to the field of calibration of optical imaging devices. Background Because the radar and the optical camera have higher ranging and angle measuring precision respectively, the radar and the optical camera are often matched for use in space-based detection so as to realize tracking detection, relative navigation and the like of targets. The premise of accurately describing the target motion by using radar and camera measurement data is to unify measurement references, namely, calibrating the relative relationship between the radar electric axis and the optical camera optical axis. The on-orbit force thermal conditions can cause certain deviations of the camera/radar photo-axis relative to the ground calibration. If the radar has angle measurement capability, the target angle measurement result output by the radar is directly read in an optical camera self-tracking state (the satellite finishes tracking and pointing to the target according to the angle measurement result of the camera, and the azimuth pitching error voltage is near zero), and after statistical averaging, the photoelectric deviation can be obtained, the angle measurement value of the target under a camera coordinate system and a radar coordinate system is obtained, and further the on-orbit calibration of the photoelectric axis is realized. However, when the radar does not have an angle measurement function, the camera and the radar cannot be calibrated on track by the conventional method. If the radar electric axis and the camera optical axis are not calibrated in-orbit, the composite detection precision is reduced, and when the radar beam angle is narrower, the radar beam can not accurately aim at a target satellite or even cannot receive a target satellite echo due to the existence of deviation between the radar electric axis and the camera optical axis when the camera optical axis points to the target satellite. The on-orbit calibration technology for photoelectric deviation of the satellite-borne radar and the camera based on the weight model solves the problem of on-orbit calibration of the radar and the camera without an angle measurement function. The current radar and camera on-orbit calibration depends on the angle measurement function of the radar and the camera, and a blank exists for a radar and camera high-precision calibration method without the angle measurement function. Disclosure of Invention The technical problem of the invention is to overcome the defects of the prior art, provide a weight model-based method for calibrating a camera and a radar photoelectric shaft on the track, and solve the problem of calibrating the radar and the camera on the track without an angle measurement function. The technical scheme of the invention is that the on-orbit calibration method of the camera and the radar photoelectric shaft based on the weight model comprises the following steps: Selecting a target for calibration, controlling the attitude of the whole star to enable the optical axis of the camera to point to the target, and recording the position of the target under the camera system; Determining a radar scanning range and a scanning step length, establishing a radar scanning coordinate system, and determining radar scanning points; traversing and scanning the determined scanning range according to a set scanning step length in sequence, transmitting radar beams at each scanning point by using a radar, dividing a plurality of virtual scattered points in a radar scanning area, determining the weight of each virtual scattered point in the current scanning range according to the echo intensity and the positions of the virtual scattered points, and continuously updating the weight of each virtual scattered point in the radar scanning range according to the radar echo condition of each scanning; Calculating the coordinates of the target under a radar scanning coordinate system according to the weights of the virtual scattered points; After the scanning is completed, the position of the target under the radar scanning system is calculated, and the included angle between the optical axis of the camera and the electric axis of the radar is determined by combining the position of the target under the camera system, so that the calibration of the camera and the radar is completed. Preferably, the selection of the targets needs to satisfy simultaneously: The target is positioned in the working distance range of the radar; the star of the target is superior to the detection sensitivity of the optical camera. Preferably, when determining the radar scan rang