Satellite-borne SAR (Synthetic Aperture Radar) scene matching curve imaging machine / electricity cooperative wave control optimization method

Abstract

The invention discloses a satellite-borne SAR (Synthetic Aperture Radar) scene matching curve imaging machine / electricity cooperative wave control optimization method. According to the method, under the condition that a transfer matrix from a satellite orbit coordinate system to a phased array beam coordinate system is known, the analysis relation of a phased array beam control angle, a satellite machine scanning rolling angle, a pitching angle, a yaw angle and an Euler angle is obtained; the method comprises the following steps: establishing a polynomial model for a satellite machine scanning adjustment angle, and obtaining a minimum machine scanning angle time sequence under the constraint of system capability by using a PSO algorithm, thereby obtaining angle time sequences of machine scanning and electric scanning respectively, and realizing satellite-borne SAR scene matching curve imaging machine / electric cooperative wave control optimization. According to the method, the problem that the existing spaceborne SAR scene matching curve imaging beam control method only uses mechanical scanning or electric scanning and lacks mechanical / electric cooperative beam control optimization capability is solved, and the defects in the prior art are overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of synthetic aperture radar, and in particular relates to a spaceborne SAR scene matching curve imaging machine / electrical coordinated wave control optimization method. Background Art

[0002] Long curve scenes are an important type of scene for spaceborne SAR observation, such as coastlines, railways, rivers, earthquake faults, etc. The imaging band of the traditional spaceborne SAR imaging mode is parallel to the satellite track. For imaging of long curve scenes, the overall width of the imaging band along the track is often increased by revisiting multiple tracks and splicing multiple imaging bands. Spaceborne SAR scene matching curve imaging generates an imaging band that "matches" the curve scene by continuously adjusting the pitch and azimuth beam pointing, thereby achieving high-efficiency imaging of long curve scenes. The phased array antenna is composed of multiple antenna units. By changing the phase and amplitude of the signal transmitted by each antenna unit channel, the beam can be quickly scanned and the shape changes can be achieved, but the scanning angle range is usually small; the scanning angle range of the satellite platform mechanical scanning is large, but there are angular velocity and angular acceleration constraints, and the scanning speed is limited. Through the coordinated control of the phased array antenna electronic scanning and the satellite platform mechanical scanning, the spaceborne SAR scene matching curve imaging can support more complex curve scene observation tasks, but there is no theoretical research on the beam control of this mode.

[0003] The existing spaceborne SAR scene matching curve imaging beam control methods all use only mechanical scanning or only electronic scanning, lack the ability to optimize mechanical / electrical coordinated beam control, and cannot give full play to the capabilities of phased array spaceborne SAR. Therefore, it is necessary to study the optimization method of mechanical / electrical coordinated beam control for spaceborne SAR scene matching curve imaging based on the characteristics of beam change under mechanical / electrical coordinated scanning and the configuration design method for spaceborne SAR scene matching curve imaging, optimize the phased array electronic scanning and satellite platform mechanical scanning angles under spaceborne SAR scene matching curve imaging, and realize mechanical / electrical coordinated beam control. Summary of the invention

[0004] In view of this, the present invention provides a method for optimizing the mechanical / electrical collaborative beam control of a spaceborne SAR scene matching curve imaging. When the transfer matrix from the satellite orbit coordinate system to the phased array beam coordinate system is known, the PSO algorithm is used to obtain the mechanical scanning angle timing with the smallest change under the system capability constraint, and the corresponding electronic scanning angle timing, thereby realizing the mechanical / electrical collaborative control of the beam pointing of the spaceborne SAR scene matching curve imaging.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is:

[0006] A spaceborne SAR scene matching curve imaging machine / electrical coordinated wave control optimization method, the specific steps include:

[0007] Step 1: Using the phased array system satellite-borne SAR non-along-track mode beam control method, the beam pointing transfer matrix is ​​combined to obtain the transfer matrix expression from the satellite orbit coordinate system to the phased array beam coordinate system;

[0008] Step 2: Using the satellite-ground configuration joint design and optimization method for off-track multi-target imaging of spaceborne SAR, the transfer matrix design result from the satellite orbit coordinate system to the phased array beam coordinate system is obtained, thereby solving the analytical relationship between the phased array beam control angle, satellite sweep roll, pitch, yaw angle and Euler angle;

[0009] Step 3: Using the analytical relationship between the electronic scanning angle and the machine scanning angle, the satellite machine scanning angle timing is established as a polynomial model to solve the corresponding electronic scanning angle timing;

[0010] Step 4: Use the PSO algorithm to optimize the machine scanning timing under the constraints of the electronic scanning angle, machine scanning angular velocity and angular acceleration range, obtain the machine scanning timing with the minimum scanning angle, and output the phased array electronic scanning beam control angles α, β and the roll, pitch and yaw angles of the satellite machine scanning adjustment. θ t , t timing.

[0011] Furthermore, the specific method of step one is:

[0012] The transfer matrix H from the satellite orbit coordinate system to the phased array antenna body coordinate system in the phased array satellite orbit2Ant , and then use the phased array system spaceborne SAR non-tracking mode beam control method to obtain the transfer matrix H from the phased array antenna body coordinate system to the phased array beam coordinate system Ant2sar , through the mutual relationship transfer matrix, the transfer matrix H from the satellite orbit coordinate system to the phased array beam coordinate system is obtained orbit2sar The relationship between the transfer matrices is:

[0013] H orbit2sar =H Ant2sar *H orbit2Ant (1)

[0014] Furthermore, H Ant2sar The expression is:

[0015]

[0016] Among them, α is the electronic scanning angle of the beam range, and β is the electronic scanning angle of the beam azimuth.

[0017] Furthermore, H orbit2sar The expression is:

[0018]

[0019] in, θ and ψ are the roll angle, pitch angle, and yaw angle in the Euler angle respectively.

[0020] Furthermore, the specific method of step 2 is:

[0021] The satellite-ground configuration joint design and optimization method for off-track multi-target imaging of spaceborne SAR is used to obtain the transfer matrix design result from the satellite orbit coordinate system to the phased array beam coordinate system. orbit2sar , get the phased array beam control angles α, β and the satellite sweep roll, pitch, and yaw angles θ t , t The analytical relationship between them is shown in the following formula:

[0022]

[0023] where h ij Denotes the transfer matrix H orbit2sar *H orbit2Ant T The element corresponding to the i-th row and j-th column in .

[0024] Furthermore, the specific method of step three is:

[0025] Using the analytical relationship between the electronic scanning angle and the machine scanning angle obtained in step 2, the satellite machine scanning angle timing is established as a polynomial model, and the corresponding electronic scanning angle timing is solved. The polynomial model of the satellite machine scanning adjustment angle (taking the third-order model as an example) is expressed as:

[0026]

[0027] in, θ t , t They are the instantaneous values ​​of the roll angle, pitch angle and yaw angle adjusted by the satellite scan.

[0028] Furthermore, the specific method of step 4 is:

[0029] The optimization function is established based on the goal of minimizing the change in the scanning angle and the system capability constraint. The PSO algorithm is used to optimize the scanning timing and output the optimal phased array electronic scanning beam control angles α and β and the roll, pitch, and yaw angles of the satellite scanning adjustment. θ t , t The optimization function is:

[0030]

[0031] The coefficients of the polynomial are c i d i、e i is the variable to be optimized; α max , β max are the maximum values ​​of the satellite's electronic scanning angles in range and azimuth directions, respectively; v r 、v p 、v y are the maximum angular velocities of the sweep roll angle, pitch angle, and yaw angle respectively; a r 、a p 、a y They are the maximum angular accelerations of the sweep roll angle, pitch angle, and yaw angle, respectively.

[0032] Beneficial effects:

[0033] 1. The present invention solves the problem that the existing methods for spaceborne SAR scene matching curve imaging beam control only use mechanical scanning or only use electronic scanning and lack the ability of mechanical / electrical collaborative beam control optimization. The present invention can realize mechanical / electrical collaborative beam control optimization under the constraints of system capabilities.

[0034] 2. In steps 1 and 2 of the present invention, when the transfer matrix from the satellite orbit coordinate system to the phased array beam coordinate system is known, the analytical relationship between the phased array beam control angle, satellite sweep roll, pitch, yaw angle and Euler angle is solved, laying a research foundation for subsequent detection and suppression.

[0035] 3. Step three of the present invention provides a machine scan timing based on a polynomial model, which can better characterize the change process of the machine scan, and at the same time, based on the above analytical relationship, solve the corresponding electrical scan timing.

[0036] 4. Step 4 of the present invention proposes a constrained PSO method, which can complete the wave control optimization of mechanical / electrical collaborative scanning while satisfying the system capacity constraints, and obtain the mechanical scanning angle timing with the smallest change and the corresponding electrical scanning timing. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a flow chart of the spaceborne SAR scene matching curve imaging machine / electrical coordinated wave control optimization method of the present invention;

[0038] Figure 2 It is a schematic diagram of the relative geometric relationship between the satellite orbit coordinate system and the phased array antenna body coordinate system of the space-borne SAR of the present invention;

[0039] Figure 3 It is a schematic diagram of the relative geometric relationship between the main body coordinate system of the spaceborne SAR scene matching curve imaging phased array antenna and the phased array beam coordinate system of the present invention;

[0040] Figure 4 The phased array beam control angles α, β and the roll, pitch and yaw angles adjusted by the sweep method of the present invention are θ t , t Simulation results; (a) beam pointing design results, (b) mechanical scanning angle optimization results, (c) electronic scanning angle optimization results, (d) mechanical scanning angular velocity optimization results, (e) mechanical scanning angular acceleration optimization results. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0042] The flowchart of the satellite-borne SAR scene matching curve imaging multi-target imaging machine / electrical coordinated wave control optimization method of the present invention is as follows: Figure 1 As shown, the present invention comprises the following steps:

[0043] Step 1: Based on the non-tracking mode beam control method of the phased array spaceborne SAR, the beam pointing transfer matrix is ​​combined to obtain the transfer matrix expression from the satellite orbit coordinate system to the phased array beam coordinate system;

[0044] In the traditional parabolic satellite-borne SAR, the SAR antenna is usually fixed to the satellite platform, and the transfer matrix H from the satellite orbit coordinate system to the antenna body coordinate system is orbit2sar Generally, Euler angles are used to describe the transfer matrix. For the same transfer matrix, different Euler angle transformation sequences correspond to different solution methods. Taking the 1-2-3 (roll-pitch-yaw) attitude transformation sequence as an example, the transfer matrix is ​​as follows:

[0045]

[0046] in θ and ψ are the roll angle, pitch angle, and yaw angle in the Euler angle respectively.

[0047] In the phased array satellite-borne SAR, the beam pointing is deflected due to the phase shift of the phased array antenna. The transfer matrix H from the satellite orbit coordinate system to the phased array antenna body coordinate system is obtained through the satellite platform scanning. orbit2Ant , its expression is exactly the same as that of formula (1), except that θ and ψ are the roll angle, pitch angle and yaw angle adjusted by the satellite platform scanning.

[0048] In the non-tracking mode beam control method of phased array spaceborne SAR, the transfer matrix H from the phased array antenna body coordinate system to the phased array beam coordinate system is given. Ant2sar The analytical expression of is as follows:

[0049]

[0050] The relative geometric relationship between the above coordinate systems is as follows Figure 2 As shown, XOZ is the azimuth profile, YOZ is the range profile, α is the angle between the beam azimuth profile and the Z axis, β is the angle between the beam range profile and the Z axis, n r is the distance profile normal vector, n a is the azimuth profile normal vector, and Z' is the intersection vector of the range and azimuth profiles. Therefore, in the phased array SAR system, the Z' axis is the direction of the antenna phase center; the X' axis is located in the azimuth profile and is perpendicular to the Z' axis; the Y' axis is solved according to the right-hand rule.

[0051] The optimization method of mechanical / electrical coordinated beam control for spaceborne SAR scene matching curve imaging first relies on the mechanical scanning of the satellite platform, and then uses the phased array electronic scanning to control the satellite beam pointing, thereby completing the observation task. The simultaneous equations (1) and (2) can obtain the transfer matrix from the satellite orbit coordinate system to the phased array beam coordinate system, which can classify the mechanical / electrical coordinated beam control problem under the phased array system into the existing system. Through Euler angle control, the existing standard control method of spaceborne SAR scene matching curve imaging is used to realize the arbitrary pointing control of the beam in three-dimensional space under the phased array system, as shown below:

[0052] H orbit2sar =H Ant2sar *H orbit2Ant (3)

[0053] Among them, H orbit2sar That is the transfer matrix from the satellite orbit coordinate system to the phased array beam coordinate system.

[0054] Step 2: Using the satellite-ground configuration joint design and optimization method for off-track multi-target imaging of spaceborne SAR, the transfer matrix design result from the satellite orbit coordinate system to the phased array beam coordinate system is obtained, thereby solving the analytical relationship between the phased array beam control angle, satellite sweep roll, pitch, yaw angle and Euler angle;

[0055] The transfer matrix H from the satellite orbit coordinate system to the phased array beam coordinate system is obtained by using the satellite-ground configuration joint design and optimization method for spaceborne SAR off-track multi-target imaging. orbit2sar Then, by combining equations (1), (2), and (3), we can obtain the phased array beam control angles α, β and the satellite sweep roll, pitch, and yaw angles. θ t , t The analytical relationship between them is shown in the following formula:

[0056]

[0057] where h ij Denotes the transfer matrix H orbit2sar *H orbit2Ant TThe element corresponding to the i-th row and j-th column in .

[0058] Step 3: Using the analytical relationship between the electronic scanning angle and the machine scanning angle, the satellite machine scanning angle timing is established as a polynomial model to solve the corresponding electronic scanning angle timing;

[0059] The satellite scanning adjustment angle is established as a polynomial model. Taking the third-order model as an example, the roll angle of the satellite scanning adjustment Pitch angle θ t , yaw angle ψ t The instantaneous value of is as follows:

[0060]

[0061] According to formula (4), the electronic scanning angle timing can be solved. Through the above steps, the mechanical / electrical coordinated beam control problem under the phased array spaceborne SAR can be classified into the existing spaceborne SAR scene matching curve imaging system, and the mechanical / electrical coordinated beam control optimization instructions under the satellite's 1-2-3 (roll-pitch-yaw) transition sequence can be obtained.

[0062] Step 4: Use the PSO algorithm to optimize the machine scanning timing under the constraints of the electronic scanning angle, machine scanning angular velocity and angular acceleration range, obtain the machine scanning timing with the minimum scanning angle, and output the phased array electronic scanning beam control angles α, β and the roll, pitch and yaw angles of the satellite machine scanning adjustment. θ t , t timing.

[0063] In practical applications, the electronic scanning capability of the satellite phased array payload should be fully utilized, and the satellite platform mechanical scanning should be used as little as possible. The optimization objective function is established to minimize the sum of the mechanical scanning angle changes; the constraints are the electronic scanning angle range constraint, the mechanical scanning maximum angular velocity constraint, and the maximum angular acceleration constraint, as shown below:

[0064]

[0065] The coefficients of the polynomial are c i d i 、e i is the variable to be optimized; α max , β max are the maximum values ​​of the satellite's electronic scanning angles in range and azimuth directions, respectively; v r 、v p 、v y are the maximum angular velocities of the sweep roll angle, pitch angle, and yaw angle respectively; a r 、a p 、a y They are the maximum angular accelerations of the sweep roll angle, pitch angle, and yaw angle, respectively.

[0066] The particle swarm optimization (PSO) algorithm can be used to obtain the optimal satellite mechanical scanning and electronic scanning angle timing under the system capacity constraints.

[0067] The above method solves the problem that the existing spaceborne SAR scene matching curve imaging beam control methods only use mechanical scanning or only use electronic scanning, and lack the ability of mechanical / electronic collaborative beam control optimization. By using the joint design and optimization method of satellite-ground configuration for non-along-track multi-target imaging of spaceborne SAR, the phased array electronic scanning beam control angles α and β and the roll, pitch and yaw angles adjusted by satellite mechanical scanning are given. θ t , t The relationship between them can be expanded to expand the existing spaceborne SAR scene matching curve imaging system and complete the phased array spaceborne SAR mechanical / electronic collaborative beam control.

[0068] Simulation experiment: The simulation parameters of the spaceborne SAR scene matching curve imaging machine / electrical coordinated wave control optimization are shown in Table 1.

[0069] Table 1 List of simulation parameters for spaceborne SAR scene matching curve imaging machine / electrical coordinated wave control optimization

[0070]

[0071] In order to verify the effectiveness of the spaceborne SAR scene matching curve imaging machine / electrical coordinated wave control optimization method, the spaceborne SAR scene matching curve imaging machine / electrical coordinated wave control optimization method described in this patent is used under the parameters in Table 1 to optimize the wave control of mechanical scanning and electronic scanning for a group of beam pointing.

[0072] exist Figure 4 (a) shows the Euler angle sequence describing the change of satellite beam pointing designed by the joint design and optimization method of satellite-ground configuration for off-track multi-target imaging of spaceborne SAR. Figure 4 (b) shows the timing of the phased array electronic scanning beam control angles α and β in the method described in this patent, Figure 4 (c) Figure 4 (d) Figure 4 (e) The roll angle, pitch angle, and yaw angle of the satellite scanning adjustment are given respectively θ t , t The angle, angular velocity, and angular acceleration timing diagram show that the method proposed in the present invention has a two-dimensional electric sweep of ±6°, a roll, pitch, and yaw angular velocity of less than 1° / s, and a roll, pitch, and yaw angular acceleration of less than 0.01° / s 2 Within the system capability boundary, the phased array electronic scanning capability is fully utilized, and the mechanical / electrical collaborative beam control of spaceborne SAR scene matching curve imaging is realized.

[0073] It can be seen that the present invention provides a method for optimizing the machine / electrical coordinated beam control of a satellite-borne SAR scene matching curve imaging. When the transfer matrix from the satellite orbit coordinate system to the phased array beam coordinate system is known, the satellite machine scan adjustment angle is established as a polynomial model through the analytical relationship between the phased array beam control angle, the satellite machine scan roll, pitch, yaw angle and the Euler angle, and the PSO algorithm is used to obtain the minimum machine scan angle timing under the system capability constraint, and finally the phased array beam control angles α, β and the satellite machine scan adjustment roll, pitch, yaw angles are output. θ t , t The timing of the spaceborne SAR scene matching curve imaging machine / electrical coordinated beam control optimization is realized. The present invention solves the problem that the existing spaceborne SAR scene matching curve imaging beam control methods only use machine scanning or only use electric scanning and lack the ability of machine / electrical coordinated beam control optimization, thus making up for the shortcomings of the prior art.

[0074] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may certainly make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A spaceborne SAR scene matching curve imaging machine / electrical coordinated wave control optimization method, characterized in that: The following steps are involved: Step 1: Using the phased array system spaceborne SAR non-tracking mode beam control method, obtain the transfer matrix from the satellite orbit coordinate system to the phased array beam coordinate system; Step 2: Using the satellite-ground configuration joint design and optimization method for off-track multi-target imaging of spaceborne SAR, the transfer matrix from the satellite orbit coordinate system to the phased array beam coordinate system is obtained, thereby solving the analytical relationship between the phased array beam control angle, satellite sweep roll, pitch, yaw angle and Euler angle; Step 3: Using the analytical relationship between the electronic scanning angle and the machine scanning angle, the satellite machine scanning angle timing is established as a polynomial model to obtain the corresponding electronic scanning angle timing; Step 4: Use the PSO algorithm to optimize the machine scanning timing under the constraints of the electronic scanning angle, machine scanning angular velocity and angular acceleration range, obtain the machine scanning timing with the minimum scanning angle, and output the timing of the phased array electronic scanning beam control angles α, β and the roll, pitch and yaw angles of the satellite machine scanning adjustment.

2. The spaceborne SAR scene matching curve imaging machine / electrical coordinated wave control optimization method as described in claim 1 is characterized in that In step 1, the transfer matrix from the satellite orbit coordinate system to the phased array antenna body coordinate system is: The transfer matrix from the phased array antenna body coordinate system to the phased array beam coordinate system is: in θ and ψ are the roll angle, pitch angle, and yaw angle in the Euler angle respectively, α is the electronic scanning angle of the beam in the range direction, and β is the electronic scanning angle of the beam in the azimuth direction.

3. The spaceborne SAR scene matching curve imaging machine / electrical coordinated wave control optimization method as described in claim 1 is characterized in that In step 1, the transfer matrix H from the satellite orbit coordinate system to the phased array beam coordinate system is generated. orbit2sar The method is: H orbit2sar =H Ant2sar *H orbit2Ant Among them, H orbit2Ant is the transfer matrix from the satellite orbit coordinate system to the phased array antenna body coordinate system, H Ant2sar is the transfer matrix from the phased array antenna body coordinate system to the phased array beam coordinate system.

4. The spaceborne SAR scene matching curve imaging machine / electrical coordinated wave control optimization method as described in claim 1 is characterized in that In step 2, the analytical relationship between the phased array beam control angles α, β and the satellite sweep roll, pitch, and yaw angles is: where h ij Denotes the transfer matrix H orbit2sar *H orbit2Ant T The element corresponding to the i-th row and j-th column in .

5. The spaceborne SAR scene matching curve imaging machine / electrical coordinated wave control optimization method as claimed in claim 1, characterized in that In step 3, the third-order polynomial model of the machine scanning angle is: where c i ,d i 、e i are the coefficients of the polynomial.

6. The spaceborne SAR scene matching curve imaging machine / electrical coordinated wave control optimization method as claimed in claim 1, characterized in that ,In step 4, the PSO algorithm optimization model is: The coefficients of the polynomial are c i ,d i 、e i is the variable to be optimized; α max , β max are the maximum values ​​of the satellite's electronic scanning angles in range and azimuth directions, respectively; v r 、v p 、v y are the maximum angular velocities of the sweep roll angle, pitch angle, and yaw angle respectively; a r 、a p 、a y They are the maximum angular accelerations of the sweep roll angle, pitch angle, and yaw angle, respectively.

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