Segmented aperture imaging and positioning method of multi-rotor unmanned aerial vehicle-borne synthetic aperture radar

A segmented aperture positioning method of a multi-rotor unmanned aerial vehicle-borne synthetic aperture radar, for calculating a flight trajectory of an unmanned aerial vehicle based on a raw echo signal from the multi-rotor unmanned aerial vehicle-borne synthetic aperture radar, comprising:

• performing a range pulse compression on the raw echo signal s(t, η) to obtain the range pulse compression signal sRC (t, η) based on a phase history φ(η) of scattering points in the sRC(t, η), where t is a fast time in a range dimension, and η is a slow time in an azimuth dimension;
• calculating an estimated velocity {circumflex over (ν)} and an estimated squint angle of the beam center {circumflex over (θ)} of a manoeuvring platform;
• segmenting the range pulse compression signal sRC(t, η) into N segments based on a direction of the estimated velocity {circumflex over (ν)}, each segment corresponding to a segmented pulse compression signal sRC,i (t, η), where i=1 . . . N;
• calculating platform trajectory coordinates
• [
• X
• k
• i
• ,
• Y
• k
• i
• ,
• Z
• k
• i
• ]
• for i-th segment based on the estimated velocity {circumflex over (ν)} and estimated the squint angle of beam center {circumflex over (θ)}, where k=1 . . . M and M is a length of said each segment in an azimuth direction, as follows:
• X
• k
• i
• =
• ∫
• v
• ˆ
• ⁢
• η
• ⁢
• d
• ⁢
• η
• ,
• Y
• k
• i
• =
• 0
• ,
• Z
• k
• i
• =
• R
• ˆ
• ⁢
• cos
• ⁢
• θ
• ˆ
• ⁢
• cos
• ⁢
• θ
• in
• ,
• where θin represents an angle between a beam direction of the multi-rotor unmanned aerial vehicle-borne synthetic aperture radar and a normal direction of the ground plane;
• extracting three scattering points in adjacent regions between the i-th and (i−1)-th segments, the coordinates of the three scattering points in the i-th segment are denoted as
• [
• Q
• 1
• i
• ,
• Q
• 2
• i
• ,
• Q
• 3
• i
• ]
• ,
• and the coordinates of the scattering points in the (i−1)-th segment are denoted as
• [
• Q
• 1
• i
• -
• 1
• ,
• Q
• 2
• i
• -
• 1
• ,
• Q
• 3
• i
• -
• 1
• ]
• ;
• calculating a rotation matrix γ for the i-th and (i−1)-th segments, based on the coordinates of the scattering points
• [
• Q
• I
• i
• -
• 1
• ,
• Q
• 2
• i
• -
• 1
• ,
• Q
• 3
• i
• -
• 1
• ]
• ⁢
• and
• [
• Q
• 1
• i
• ,
• Q
• 2
• i
• ,
• Q
• 3
• i
• ]
• ,
• as
• ⁢
• follows
• :
• γ
• =
• [
• Q
• 1
• i
• -
• 1
• ,
• Q
• 2
• i
• -
• 1
• ,
• Q
• 3
• i
• -
• 1
• ]
• ·
• [
• Q
• 1
• i
• ,
• Q
• 2
• i
• ,
• Q
• 3
• i
• ]
• -
• 1
• ;
• rotating the platform trajectory coordinates of the i-th segment utilizing the platform trajectory coordinates of the (i−1)-th segment
• [
• X
• k
• i
• -
• 1
• ,
• Y
• k
• i
• -
• 1
• ,
• Z
• k
• i
• -
• 1
• ]
• as a reference to align the platform trajectory coordinates of adjacent segments, as follows:
• [
• X
• k
• i
• -
• 1
• ,
• Y
• k
• i
• -
• 1
• ,
• Z
• k
• i
• -
• 1
• ]
• =
• γ
• ·
• [
• X
• k
• i
• ,
• Y
• k
• i
• ,
• Z
• k
• i
• ]
• ;
• performing a coherent integration of the platform trajectory coordinates in an overlapping region of the i-th and (i−1)-th segments, and concatenating the platform trajectory coordinates in a non-overlapping region to obtain concatenated trajectory coordinates
• [
• P
• x
• i
• ,
• P
• y
• i
• ,
• P
• z
• i
• ]
• ,
• as
• ⁢
• follows
• ⁢
• :
• [
• P
• x
• ,
• P
• y
• ,
• P
• z
• ]
• =
• [
• X
• k
• i
• ,
• Y
• k
• i
• ,
• Z
• k
• i
• ]
• +
• [
• X
• k
• i
• -
• 1
• ,
• Y
• k
• i
• -
• 1
• ,
• Z
• k
• i
• -
• 1
• ]
• ;
• repeating the steps of extracting the three scattering points, calculating the rotation matrix,
• rotating the platform trajectory coordinates, performing the coherent integration and concatenating the platform trajectory coordinates until spliced trajectory coordinates [Px, Py, Pz] for all segments are obtained, so as to obtain final trajectory coordinates
• [
• P
• x
• all
• ,
• P
• y
• all
• ,
• P
• Z
• all
• ]