CN109633575B - Three-axis calibration system and method for satellite-borne microwave optical composite radar - Google Patents
Three-axis calibration system and method for satellite-borne microwave optical composite radar Download PDFInfo
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Abstract
The invention relates to a three-axis calibration system and a method of a satellite-borne microwave optical composite radar, wherein the calibration system comprises: the system comprises a target simulation subsystem, a surveying and mapping subsystem, a radar test platform and a radar device; the radar test platform comprises a supporting platform, a radar mounting frame and a two-dimensional rotary table; the target simulation subsystem comprises a microwave and visible light simulation source, a target simulation two-dimensional scanning frame and a microwave optical composite simulation front end; the surveying and mapping subsystem comprises two theodolites and a laser tracker. The calibration method comprises the following steps: step 1, adjusting a two-dimensional turntable to enable a radar antenna plane to be parallel to a target simulation plane; step 2, adjusting the azimuth direction of a microwave electric axis system to be parallel to the target simulation azimuth direction; step 3, calibrating the relation between the plane of the radar antenna and a prism coordinate system of a radar antenna base; step 4, calibrating the relation among the optical axis, the electric axis and the mechanical axis; and 5, correcting the radar measurement result according to the calibration result, and finishing the calibration process.
Description
Technical Field
The invention relates to a test technology of a satellite-borne microwave optical composite radar, which is used for calibrating a mechanical axis, an optical axis and an electric axis of the satellite-borne microwave optical composite radar.
Background
In the prior art, radars for which radar axis calibration is usually performed are single-system radars, and are mostly calibrated for two axes of a mechanical axis and an electric axis or a mechanical axis and an optical axis. The technology of optical axis, electric axis and mechanical axis three-axis calibration of multiple radar systems is usually used for calibrating ground radar. Due to the serious difference between the optical environment and the target characteristics of the ground radar and the satellite-borne radar, the calibration method for the ground radar is not suitable for the satellite-borne radar.
The optical axis and electric axis calibration method mentioned in the research on tracking radar shafting calibration method (Master academic paper of Western electronic science and technology university, 2015) and the new radar photoelectric axis consistency calibration method (modern radar, Vol.35No.5, May.2013) is a calibration method for ground radar, the optical axis is determined by an optical cross line of an optical sighting telescope, the microwave electric axis is determined by a microwave horn antenna, and the calibration is completed by measuring the difference between the two methods. However, the method for determining the optical axis is not suitable for the satellite-borne radar, and the satellite-borne radar cannot complete the determination of the optical axis through the method. The calibration methods mentioned in the practice of the microwave radar coordinate system high-precision calibration method ("space electronic technology", 2016 (th) 6) and the radar optical axis calibration technology ("digital technology and application", 2014 (th) 6) are calibrated only for a single axis system. In the patent of electrical axis optical calibration system of satellite-borne microwave tracking and aiming radar and calibration method thereof (patent application number: CN 201310414744 patent publication number: CN103454619), calibration is only performed on an electrical axis and a mechanical axis of a microwave radar, and the calibration method is complex.
Disclosure of Invention
The invention aims to provide a method for calibrating three shafts, namely a mechanical shaft, an optical shaft and an electric shaft of a satellite-borne microwave optical composite radar in a compact range.
In order to achieve the purpose, the invention is realized by the following technical scheme:
a three-axis calibration system of a satellite-borne microwave optical composite radar is characterized by comprising: the system comprises a target simulation subsystem, a surveying and mapping subsystem, a radar test platform and a radar device;
the radar device comprises a microwave optical composite radar and radar measurement and control equipment;
the radar measurement and control equipment is connected with the microwave optical composite radar and controls the microwave optical composite radar to work;
the radar test platform comprises a supporting platform, a radar mounting frame and a two-dimensional rotary table;
the two-dimensional rotary table is arranged on the supporting platform, the radar mounting frame is arranged on the two-dimensional rotary table, and the microwave optical composite radar is arranged on the radar mounting frame;
the target simulation subsystem comprises a microwave and visible light simulation source, a target simulation two-dimensional scanning frame and a microwave optical composite simulation front end;
the microwave and visible light simulation source is connected with the microwave optical composite radar and connected with a microwave optical composite simulation front end, and the microwave optical composite simulation front end is arranged on a target simulation two-dimensional scanning frame;
the microwave optical composite radar and the microwave optical composite simulation front end are on the same horizontal line;
the target simulation two-dimensional scanning frame has the functions of azimuth pitching two-dimensional scanning and azimuth pitching upward rotation simulation front end;
the prism used in the calibration process comprises a radar antenna base prism, a radar antenna side prism and a microwave optical composite simulation front end prism;
the radar antenna base prism is arranged on a base of the radar antenna, the radar antenna side prism is arranged on the side surface of the radar antenna, and the microwave optical composite simulation front end prism is arranged on the side surface of the microwave optical composite simulation front end;
the surveying and mapping subsystem comprises a first theodolite, a second theodolite and a laser tracker;
the laser tracker is arranged on one side of the microwave optical composite radar, and the first theodolite and the second theodolite are arranged on the other side of the microwave optical composite radar;
the laser tracker finds the center of the microwave optical composite radar antenna plane, and the rotation angle of the antenna is cooperatively measured through the two theodolites.
Preferably, the radar test platform further comprises a controller connected with the two-dimensional turntable.
Preferably, the microwave optical composite analog front end makes the simulated target visible light and microwave concentric in two modes.
Preferably, the structure of the microwave optical composite simulation front end is a prism structure, a hole is formed in the short side surface of the microwave horn antenna, the microwave optical composite simulation front end prism is installed, and an input path is provided for scattering light emitted by the visible light simulation source; two star point plates are respectively arranged at the middle part and the front end of the horn, and a hole is formed in the center of each star point plate to ensure the parallelism of visible light emitted by the composite front end; the front star point plate and the rear star point plate at the analog composite front end and the material between the front star point plate and the rear star point plate are made of wave-transparent and light-tight polytetrafluoroethylene materials.
A three-axis calibration method of a satellite-borne microwave optical composite radar comprises the following steps:
step 1, adjusting a two-dimensional turntable to enable a radar antenna plane to be parallel to a target simulation plane;
step 2, adjusting the azimuth direction of a microwave electric axis system to be parallel to the target simulation azimuth direction;
step 4, calibrating the relation among the optical axis, the electric axis and the mechanical axis;
and 5, correcting the radar measurement result according to the calibration result, and finishing the calibration process.
Preferably, the step 1 further comprises the steps of:
step 1.1, controlling a radar mechanism to keep the radar mechanism at a zero position by utilizing radar measurement and control equipment;
step 1.2, respectively taking more than or equal to 4 points on a radar antenna plane and a target simulation plane, wherein any 3 points are not collinear;
step 1.3, setting the coordinate of each point on the plane of the radar antenna as (x)1n,y1n,z1n) (n is 1,2, …,10), and coordinates of each point on the object simulation plane are set to (x)2n,y2n,z2n)(n＝1,2,…,10)；
Step 1.4, constructing a matrix by using coordinates of each point on a radar antenna plane
Step 1.5, calculating the solution of the over-determined equation: xSolution 0＝(AΤWA)-1AΤWB；
Step 1.6, calculating an initial deviation solution value: Δ B ═ B-AXSolution 0；
Step 1.7, adjusting the weight matrix W according to the initial deviation valueSolution 0Setting the weight of the point meeting the condition as zero and the point with deviation exceeding the threshold value as the weight according to the deviation value in a certain proportion, and constructing a weight matrix WSolution 0；
Step 1.8, calculate iterative solution XSolution 1＝XSolution 0-(AΤWSolution 0A)-1AΤWSolution 0Δ B, iterate until WSolution 0All zero is obtained;
the final equation is obtained as
Step 1.9, obtaining the plane of the radar antenna as x + b1y+c1z＝d1(ii) a Obtaining the target simulation plane as x + b in the same way2y+c2z＝d2；
And step 1.10, adjusting a two-dimensional turntable of the radar test platform according to a plane equation of the two planes, so that the target simulation plane is parallel to the plane of the radar antenna.
Preferably, the step 2 further comprises the following steps:
step 2.1, finding the center of the radar antenna plane through a laser tracker, determining a normal of the antenna plane at the center of the antenna, and placing the composite simulation front end at the intersection point of the normal and a target simulation plane;
step 2.2, controlling the composite radar to track the target in a microwave mode, and after stable tracking, using a first theodolite auto-collimation antenna plane side prism as an angle zero point theta of an antenna planeMicro 0Recording the position of the composite simulation front end at the moment and taking the position as a microwave simulation angle zero point;
step 2.3, controlling the target simulation two-dimensional scanning frame to enable the composite simulation front end to move a distance d along the target simulation azimuth direction, and calculating the angle of the composite simulation front end according to the distance
θ＝arctan(d/l)
Wherein l is the distance from the target plane to the antenna plane;
and 2.4, controlling the composite radar to track the target in a microwave mode, and after stable tracking, cooperatively measuring the antenna rotation angle theta by using two theodolitesMicro-meterRecording a target simulation angle theta; repeating the operation to obtain multiple measurement data;
step 2.5, constructing a function theta by using the multiple measurement data and using the theta as an independent variableMicro-meter＝kMicro-meterTheta, adopting a weighted iterative least square method;
wherein k isMicro-meterRepresenting the rotation angles of the azimuth direction and the pitching direction of the microwave electric axis to the target simulation azimuth direction and pitching direction;
if k isMicro-meterIf the direction is 1, the microwave electric axis direction is parallel to the target simulation direction, and the microwave electric axis pitch direction is parallel to the target simulation pitch direction;
if k isMicro-meter<1 indicates that the orientation of the microwave electric axis is not parallel to the orientation of the target simulation;
step 2.6, calculating the rotation angle omega according to a formulaMicro-meter＝arccos(kMicro-meter) And adjusting a two-dimensional turntable of the radar test platform according to the direction so that the direction of the microwave electric axis is parallel to the direction of the target simulation direction.
Preferably, the step 3 further comprises the following steps:
3.1, utilizing the first warp-weft instrument to perform auto-collimation with the antenna base prism, wherein the collimation direction is the X direction which is vertical to the plane direction of the antenna base and is used as the coordinate system of the antenna base prism;
3.2, utilizing the second theodolite to perform auto-collimation with the antenna base prism, wherein the collimation direction is parallel to the ground plane direction and is used as the Y direction of the antenna base prism coordinate system;
3.3, determining the Z direction of the prism coordinate system of the antenna base by using a right-hand spiral rule;
3.4, respectively placing measuring heads of the laser tracker on the first theodolite and the second theodolite, and measuring the coordinates of the two theodolites;
step 3.5, moving the first warp-weft instrument for a certain distance under the condition of keeping the auto-collimation of the first warp-weft instrument, then placing a measuring head of the laser tracker on the first warp-weft instrument, and obtaining a coordinate again;
3.6, axially constructing an antenna base prism coordinate system by using the three coordinates and the three coordinates;
and 3.7, constructing the relation between the plane of the radar antenna and the prism coordinate system of the antenna base according to the measured plane coordinate system of the radar antenna and the relation between the prism coordinate system of the antenna base and the coordinate system of the laser tracker.
Preferably, the step 4 further comprises the following steps:
step 4.1, controlling the target simulation two-dimensional scanning frame to enable the composite simulation front end to move a certain distance d along the direction of the target simulation plane, and calculating an angle theta of the composite simulation front end as arctan (d/l) according to the distance; wherein l is the distance from the target plane to the antenna plane;
and 4.2, controlling the composite radar to track the target in a microwave mode, and measuring the feedback angle of the mechanism at the moment after stable tracking
Recording a target simulation angle theta; repeating the operation to obtain multiple groups of measurement data;
step 4.3, using a plurality of groups of measurement data, using theta as an independent variable and using thetaMechanism，
The data each construct a linear function θMechanism＝kMechanismθ+ΔθMechanism，
Wherein, Delta thetaMechanismThe angular difference between the mechanical axis and the microwave electric axis in the direction of the axis of the microwave electric axis is shown,
representing the angle difference between the mechanical axis and the microwave electric axis in the pitching direction of the microwave electric axis system;
determining by using a weighted least square iteration method when constructing a linear function;
step 4.4, kMechanismAnd
indicates that an angle exists between the azimuth direction of the mechanical axis system and the azimuth direction of the microwave electric axis system
The included angle of (A);
step 4.5, controlling the radar mechanism to keep the radar mechanism at a zero position by using radar measurement and control equipment, controlling a target to simulate a two-dimensional scanning frame, moving the composite simulation front end by a certain distance d along the Y direction, and calculating an angle theta (arctan (d/l)) of the composite simulation front end according to the distance; determining the rotation angle of the composite simulation front end to be theta by matching the two theodolites;
and 4.6, controlling the composite radar to track the target in an optical mode, and recording the target angle measured in the optical mode of the composite radar at the moment after stable tracking
Recording a target simulation angle theta; repeating the operation to obtain multiple groups of measurement data;
step 4.7, using a plurality of groups of measurement data, using theta as an independent variable and using thetaLight (es)，
The data each construct a linear function θLight (es)＝kLight (es)θ+ΔθLight (es)，
Wherein, Delta thetaLight (es)The angular difference between the visible light axis and the microwave electric axis in the direction of the microwave electric axis is shown,
representing the visible axis and the microThe angle difference of the wave electric shaft in the pitching direction of the wave electric shaft system is larger;
determining by using a weighted least square iteration method when constructing a linear function;
klight (es)And
the angle between the azimuth direction of the visible optical axis and the azimuth direction of the microwave optical axis is shown as
The included angle of (a).
Preferably, the step 5 further comprises the steps of:
step 5.1, calibrating a microwave pitching shafting; rotating the system by 90 degrees, repeating the steps 1-4, completing the calibration of the pitching direction of the system, and determining the non-perpendicularity of the azimuth direction and the pitching direction of the microwave electric axis system according to the calibration result;
step 5.2, correcting the measurement result according to the calibration result; and correcting the measurement result into a microwave electric axis system according to the calibration result, and finally correcting the calibration result into an antenna base prism coordinate system according to the relation between the radar antenna plane and the antenna base prism coordinate system.
Compared with the background technology, the invention has the following advantages:
1. the invention utilizes the specially designed composite analog front end structure to solve the problem that the positions of the simulated visible light target and the simulated microwave target are difficult to unify;
2. the calibration method can finish the calibration of the satellite-borne radar in a compact range, and can ensure the requirements of the satellite-borne radar on temperature, humidity and air cleanliness;
3. the invention can carry out calibration under the environment without background light, which is consistent with the working environment of the satellite-borne microwave optical composite radar;
4. the invention can complete the calibration of three shafts of a mechanical shaft, an optical shaft and an electric shaft of the multi-system radar, namely a microwave optical composite radar;
5. the calibration method can calibrate the rotation relation among the mechanical axis system, the microwave electric axis system and the visible light axis system, and not only calibrate the axis deviation.
6. The plane determination and the linear fitting of the measurement result are all completed by adopting an optimization method, so that the method has higher calibration precision;
7. the calibration result of the invention can be directly mapped into the prism coordinate system of the radar antenna base, thereby facilitating the transmission of the calibration result in the spacecraft coordinate system.
Drawings
FIG. 1 is a system architecture diagram of the calibration system of the present invention;
FIG. 2 is a schematic view of the prism position of the calibration system of the present invention;
FIG. 3 is a schematic diagram of a microwave-optical composite analog front end of the present invention;
fig. 4 is a flowchart of a calibration method applied to three-axis calibration of a satellite-borne microwave optical composite radar.
Detailed Description
In order to make the technical means, the original characteristics, the achieved purposes and the effects of the invention easy to understand, the invention is further explained in detail with the accompanying drawings and the specific embodiments, but the scope of the invention is not limited in any way.
As shown in fig. 1 and fig. 2, a three-axis calibration system of a satellite-borne microwave optical composite radar includes: the system comprises a target simulation subsystem, a surveying and mapping subsystem, a radar test platform (3) and a radar device. The radar device comprises a microwave optical composite radar (41) and a radar measurement and control device (42); the radar measurement and control equipment (42) is connected with the microwave optical composite radar (41) and controls the microwave optical composite radar (41) to work; the radar test platform comprises a supporting platform (31), a radar mounting frame (32) and a two-dimensional rotary table (33); the two-dimensional rotary table (33) is installed on the supporting platform (31), the radar mounting frame (32) is installed on the two-dimensional rotary table (33), and the microwave and optical composite radar (41) is installed on the radar mounting frame (32). The target simulation subsystem comprises a microwave and visible light simulation source (11), a microwave optical composite simulation front end (12) and a target simulation two-dimensional scanning frame (13); the microwave and visible light simulation source (11) is connected with the microwave optical composite radar (41) and is connected with a microwave optical composite simulation front end (12), and the microwave optical composite simulation front end (12) is arranged on a target simulation two-dimensional scanning frame (13); the microwave optical composite radar (41) and the microwave optical composite simulation front end (12) are on the same horizontal line; the microwave optical composite simulation front end (12) enables simulated target visible light and microwaves to be in the same mode; the target simulation two-dimensional scanning frame (13) has an azimuth pitching two-dimensional scanning function and an azimuth pitching upward rotating simulation front end function.
The prism position used in the calibration process is shown in fig. 2, and comprises a radar antenna base prism (411), a radar antenna side prism (412) and a microwave optical composite analog front end prism (121); the radar antenna base prism (411) is arranged on the base of the radar antenna, the radar antenna side prism (412) is arranged on the side face of the radar antenna, and the microwave optical composite simulation front end prism (121) is arranged on the side face of the microwave optical composite simulation front end. The surveying and mapping subsystem comprises a first theodolite (21), a second theodolite (22) and a laser tracker (23); the laser tracker (23) is arranged on one side of the microwave optical composite radar (41), and the first theodolite (21) and the second theodolite (22) are arranged on the other side of the microwave optical composite radar (41); the laser tracker (23) finds the center of the antenna plane of the microwave optical composite radar (41), and the rotation angle of the antenna is cooperatively measured through the two theodolites.
Fig. 3 shows the structure of the microwave optical composite analog front end, where holes are drilled on the short side of the microwave horn antenna to provide an input path for the scattered light from the visible analog source. Two star point plates are respectively arranged at the middle part and the front end of the horn, and a hole is formed in the center of each star point plate to ensure the parallelism of visible light emitted by the composite front end. The front star point plate and the rear star point plate at the analog composite front end and the material between the front star point plate and the rear star point plate are made of wave-transparent and light-tight polytetrafluoroethylene materials.
Fig. 4 is a flowchart of a calibration method applied to three-axis calibration of a satellite-borne microwave optical composite radar. The calibration process is carried out in five steps in sequence, step 1, the two-dimensional turntable is adjusted to enable the plane of the radar antenna to be parallel to the target simulation plane; step 2, adjusting the azimuth direction of a microwave electric axis system to be parallel to the target simulation azimuth direction; step 3, calibrating the relation between the plane of the radar antenna and a prism coordinate system of a radar antenna base; step 4, calibrating the relation among the optical axis, the electric axis and the mechanical axis; and 5, correcting the radar measurement result according to the calibration result, and finishing the calibration process.
The step 1 further comprises the following processes:
the radar measuring and controlling equipment is used for controlling the radar mechanism to keep the radar mechanism at a zero position, 10 points (more than or equal to 4, and any 3 points are not collinear) are respectively taken on a radar antenna plane and a target simulation plane, and coordinates of each point on the radar antenna plane are (x)1n,y1n,z1n) (n is 1,2, …,10), and coordinates of each point on the target simulation plane are (x)2n,y2n,z2n) (n-1, 2, …, 10). Matrix construction by using coordinates of each point on radar antenna plane
Calculating a solution to the over-determined equation: xSolution 0＝(AΤWA)-1AΤWB
Calculating an initial solution deviation value: Δ B ═ B-AXSolution 0
Adjusting the weight matrix W according to the initial deviation valueSolution 0Setting the weight of the point meeting the condition as zero and the point with deviation exceeding the threshold value as the weight according to the deviation value in a certain proportion, and constructing a weight matrix WSolution 0。
Computing an iterative solution XSolution 1＝XSolution 0-(AΤWSolution 0A)-1AΤWSolution 0ΔB
Iterate until WSolution 0All zeros up (i.e., each point satisfies the condition). The final equation is obtained as
The plane of the obtained radar antenna is as follows: x + b1y+c1z＝d1。
The target simulation plane obtained by the same method is as follows: x + b2y+c2z＝d2. And adjusting a two-dimensional turntable of the radar test platform according to the plane equation of the two planes to enable the target simulation plane to be parallel to the plane of the radar antenna.
The step 2 further comprises the following processes:
under the condition that a radar antenna plane and a target simulation plane are known, the center of the radar antenna plane is found through a laser tracker, a normal line passing through the antenna center antenna plane is determined, and a composite simulation front end is placed at the intersection point of the normal line and the target simulation plane. Controlling the composite radar to track the target in a microwave mode, after stable tracking, using a first theodolite auto-collimation antenna plane side prism as an angle zero point theta of an antenna planeMicro 0And recording the position of the composite simulation front end at the moment and taking the position as the microwave simulation angle zero point.
The target simulation two-dimensional scanning frame is controlled to move the composite simulation front end by a certain distance d along the target simulation azimuth direction, and the angle theta of the composite simulation front end is calculated to be arctan (d/l) (l is the distance from the target plane to the antenna plane). Controlling the composite radar to track a target in a microwave mode, and after stable tracking, cooperatively measuring the antenna rotation angle theta by using two theodolites (the angle measuring range of a single theodolite is insufficient, and the working mode of double theodolites is adopted here)Micro-meterAnd recording the target simulation angle theta. This operation is repeated to obtain a plurality of measurement data.
Constructing a function theta by using multiple measurement data and taking theta as an independent variableMicro-meter＝kMicro-meterThe method for constructing the function is consistent with the method for solving the antenna plane equation, and a weighted iteration least square method is adopted. k is a radical ofMicro-meterRepresenting the rotation angles of the azimuth direction and the pitch direction of the microwave electric axis to the simulated azimuth direction and the pitch direction of the target, if kMicro-meterThe microwave electric axis direction is parallel to the target simulation azimuth direction, and the microwave electric axis pitch direction is parallel to the target simulation pitch direction. If k isMicro-meter<1 represents that the orientation of the microwave electric axis is not parallel to the target simulation orientation, and the rotation angle omega is calculated according to a formulaMicro-meter＝arccos(kMicro-meter) And adjusting a two-dimensional turntable of the radar test platform according to the direction so that the direction of the microwave electric axis is parallel to the direction of the target simulation direction.
The step 3 further comprises the following processes:
the first warp-weft instrument and the antenna base prism are used for auto-collimation, and the collimation direction is perpendicular to the plane direction of the antenna base and is used as the X direction of the antenna base prism coordinate system;
utilizing a second theodolite and the antenna base prism to perform auto-collimation, wherein the collimation direction is parallel to the ground plane direction and is used as the Y direction of the antenna base prism coordinate system;
determining the Z direction of the prism coordinate system of the antenna base by using a right-hand screw rule;
respectively placing measuring heads of the laser tracker on the first theodolite and the second theodolite, and measuring the coordinates of the two theodolites;
moving the first warp-weft instrument for a certain distance under the condition of keeping the auto-collimation of the first warp-weft instrument, then placing a measuring head of the laser tracker on the first warp-weft instrument, and obtaining a coordinate again;
and (4) axially constructing an antenna base prism coordinate system by using three coordinates and three coordinates.
The measured radar antenna plane is determined by a laser tracker coordinate system, and the relation between the radar antenna plane and the antenna base prism coordinate system is constructed according to the relation between the antenna base prism coordinate system and the laser tracker coordinate system.
The step 4 further comprises the following processes:
and controlling the target simulation two-dimensional scanning frame to move the composite simulation front end by a certain distance d along the direction of the target simulation plane, and calculating the angle theta of the composite simulation front end, which is arctan (d/l) (wherein l is the distance from the target plane to the antenna plane), according to the distance. Controlling the composite radar to track the target in a microwave mode, and measuring the feedback angle of the mechanism at the moment after stable tracking
The target simulation angle θ is recorded. This operation is repeated to obtain a plurality of sets of measurement data.
Using multiple sets of measured data, with theta as independent variable and thetaMechanism，
The data each construct a linear function θMechanism＝kMechanismθ+ΔθMechanism，
The method for constructing the linear function is the same as the method for determining the antenna plane, and the method for determining the antenna plane is a weighted least square iteration method.
kMechanismAnd
indicates that an angle exists between the azimuth direction of the mechanical axis system and the azimuth direction of the microwave electric axis system
Angle of (d), Delta thetaMechanismThe angular difference between the mechanical axis and the microwave electric axis in the direction of the axis of the microwave electric axis is shown,
and the angle difference between the mechanical axis and the microwave electric axis in the pitching direction of the microwave electric axis system is shown.
The radar mechanism is controlled by utilizing radar measurement and control equipment to be kept at a zero position, the target simulation two-dimensional scanning frame is controlled, the composite simulation front end moves a certain distance d along the Y direction, the angle theta of the composite simulation front end is calculated as arctan (d/l) (l is the distance from a target plane to an antenna plane) according to the distance, and two theodolites are matched to determine that the rotation angle of the composite simulation front end is theta by using two theodolites (the angle measuring range of a single theodolite is insufficient, and the working mode of the double theodolites is adopted). Controlling the composite radar to track the target in an optical mode, and recording the target angle measured in the optical mode of the composite radar after stable tracking
The target simulation angle θ is recorded. This operation is repeated to obtain a plurality of sets of measurement data.
Using multiple sets of measured data, with theta as independent variable and thetaLight (es)，
The data each construct a linear function θLight (es)＝kLight (es)θ+ΔθLight (es)，
The method for constructing the linear function is the same as the method for determining the antenna plane, and the method for determining the antenna plane is a weighted least square iteration method.
kLight (es)And
the angle between the azimuth direction of the visible optical axis and the azimuth direction of the microwave optical axis is shown as
Angle of (d), Delta thetaLight (es)The angular difference between the visible light axis and the microwave electric axis in the direction of the microwave electric axis is shown,
and the angle difference between the visible light axis and the microwave electric axis in the pitching direction of the microwave electric axis system is represented.
The step 5 further comprises the following processes:
and (4) rotating the system by 90 degrees, and repeating the steps 1-4 to finish the calibration of the pitching direction of the system. And determining the non-perpendicularity of the azimuth direction and the pitching direction of the microwave electric axis system according to the calibration result.
And correcting the measurement result into a microwave electric axis system according to the calibration result, and finally correcting the calibration result into an antenna base prism coordinate system according to the relation between the radar antenna plane and the antenna base prism coordinate system.
While the present invention has been described in detail by way of the foregoing preferred examples, it is to be understood that the above description is not to be taken as limiting the invention. Various modifications and alterations to this invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the scope of the invention should be determined from the following claims.
Claims (7)
1. A three-axis calibration system of a satellite-borne microwave optical composite radar is characterized by comprising: the system comprises a target simulation subsystem, a surveying and mapping subsystem, a radar test platform and a radar device;
the radar device comprises a microwave optical composite radar (41) and radar measurement and control equipment;
the radar measurement and control equipment is connected with the microwave optical composite radar (41) and controls the microwave optical composite radar (41) to work;
the radar test platform comprises a supporting platform (31), a radar mounting frame (32) and a two-dimensional rotary table (33);
the two-dimensional rotary table (33) is arranged on the supporting platform (31), the radar mounting frame (32) is arranged on the two-dimensional rotary table (33), and the microwave optical composite radar (41) is arranged on the radar mounting frame (32);
the target simulation subsystem comprises a microwave and visible light simulation source (11), a target simulation two-dimensional scanning frame (13) and a microwave optical composite simulation front end (12);
the microwave and visible light simulation source (11) is connected with the microwave optical composite radar (41) and is connected with a microwave optical composite simulation front end (12), and the microwave optical composite simulation front end (12) is arranged on a target simulation two-dimensional scanning frame (13);
the microwave optical composite radar (41) and the microwave optical composite simulation front end (12) are on the same horizontal line;
the target simulation two-dimensional scanning frame (13) has the functions of azimuth pitching two-dimensional scanning and azimuth pitching upward rotating simulation front end;
the prism used in the calibration process comprises a radar antenna base prism (411), a radar antenna side prism (412) and a microwave optical composite simulation front end prism (121);
the radar antenna base prism (411) is arranged on the base of the radar antenna, the radar antenna side prism (412) is arranged on the side face of the radar antenna, and the microwave optical composite simulation front end prism (121) is arranged on the side face of the microwave optical composite simulation front end;
the surveying and mapping subsystem comprises a first theodolite (21), a second theodolite (22) and a laser tracker (23);
the laser tracker (23) is arranged on one side of the microwave optical composite radar (41), and the first theodolite (21) and the second theodolite (22) are arranged on the other side of the microwave optical composite radar (41);
the laser tracker (23) finds the center of the antenna plane of the microwave optical composite radar (41), and the rotation angle of the antenna is cooperatively measured through the two theodolites;
the radar test platform further comprises a controller (34) which is connected with the two-dimensional rotary table (33);
the microwave optical composite simulation front end (12) enables simulated target visible light and microwaves to be concentric in two modes;
the structure of the microwave optical composite simulation front end is a prism structure, holes are formed in the short side faces of the microwave horn antenna, the microwave optical composite simulation front end prism (121) is installed, and an input path is provided for scattered light emitted by a visible light simulation source; two star point plates are respectively arranged at the middle part and the front end of the horn, and a hole is formed in the center of each star point plate to ensure the parallelism of visible light emitted by the composite front end; the front star point plate and the rear star point plate at the analog composite front end and the material between the front star point plate and the rear star point plate are made of wave-transparent and light-tight polytetrafluoroethylene materials.
2. A triaxial calibration method for a spaceborne microwave optical composite radar, which is characterized in that the triaxial calibration system of the spaceborne microwave optical composite radar in claim 1 is used, and the triaxial calibration method comprises the following steps:
step 1, adjusting a two-dimensional turntable to enable a radar antenna plane to be parallel to a target simulation plane;
step 2, adjusting the azimuth direction of a microwave electric axis system to be parallel to the target simulation azimuth direction;
step 3, calibrating the relation between the plane of the radar antenna and a prism coordinate system of a radar antenna base;
step 4, calibrating the relation among the optical axis, the electric axis and the mechanical axis;
and 5, correcting the radar measurement result according to the calibration result, and finishing the calibration process.
3. The three-axis calibration method of the spaceborne microwave optical composite radar as claimed in claim 2, wherein the step 1 further comprises the following steps:
step 1.1, controlling a radar mechanism to keep the radar mechanism at a zero position by utilizing radar measurement and control equipment;
step 1.2, respectively taking more than or equal to 4 points on a radar antenna plane and a target simulation plane, wherein any 3 points are not collinear;
step 1.3, setting the coordinate of each point on the plane of the radar antenna as (x)1n,y1n,z1n) (n is 1,2, …,10), and coordinates of each point on the object simulation plane are set to (x)2n,y2n,z2n)(n＝1,2,…,10)；
Step 1.4, constructing a matrix by using coordinates of each point on a radar antenna plane
Step 1.5, calculating the solution of the over-determined equation: xSolution 0＝(AΤWA)-1AΤWB；
Step 1.6, calculating an initial deviation solution value: Δ B ═ B-AXSolution 0；
Step 1.7, adjusting the weight matrix W according to the initial deviation valueSolution 0Setting the weight of the point meeting the condition as zero and the point with deviation exceeding the threshold value as the weight according to the deviation value in a certain proportion, and constructing a weight matrix WSolution 0；
Step 1.8, calculate iterative solution XSolution 1＝XSolution 0-(AΤWSolution 0A)-1AΤWSolution 0Δ B, iterate until WSolution 0All zero is obtained;
the final equation is obtained as
m is the iteration number;
step 1.9 to obtainTo the radar antenna plane x + b1y+c1z＝d1(ii) a Obtaining the target simulation plane as x + b in the same way2y+c2z＝d2；
And step 1.10, adjusting a two-dimensional turntable of the radar test platform according to a plane equation of the two planes, so that the target simulation plane is parallel to the plane of the radar antenna.
4. The three-axis calibration method of the spaceborne microwave optical composite radar as claimed in claim 3, wherein the step 2 further comprises the following steps:
step 2.1, finding the center of the radar antenna plane through a laser tracker, determining a normal of the antenna plane at the center of the antenna, and placing the composite simulation front end at the intersection point of the normal and a target simulation plane;
step 2.2, controlling the composite radar to track the target in a microwave mode, and after stable tracking, using a first theodolite auto-collimation antenna plane side prism as an angle zero point theta of an antenna planeMicro 0Recording the position of the composite simulation front end at the moment and taking the position as a microwave simulation angle zero point;
step 2.3, controlling the target simulation two-dimensional scanning frame to enable the composite simulation front end to move a distance d along the target simulation azimuth direction, and calculating the angle of the composite simulation front end according to the distance
θ＝arctan(d/l)
Wherein l is the distance from the target plane to the antenna plane;
and 2.4, controlling the composite radar to track the target in a microwave mode, and after stable tracking, cooperatively measuring the antenna rotation angle theta by using two theodolitesMicro-meterRecording a target simulation angle theta; repeating the operation to obtain multiple measurement data;
step 2.5, constructing a function theta by using the multiple measurement data and using the theta as an independent variableMicro-meter＝kMicro-meterTheta, adopting a weighted iterative least square method;
wherein k isMicro-meterRepresenting the rotation angles of the azimuth direction and the pitching direction of the microwave electric axis to the target simulation azimuth direction and pitching direction;
if k isMicro-meterIf the direction is 1, the microwave electric axis direction is parallel to the target simulation direction, and the microwave electric axis pitch direction is parallel to the target simulation pitch direction;
if k isMicro-meterIf the azimuth of the microwave electric axis is less than 1, the azimuth of the microwave electric axis is not parallel to the target simulation azimuth;
step 2.6, calculating the rotation angle omega according to a formulaMicro-meter＝arccos(kMicro-meter) And adjusting a two-dimensional turntable of the radar test platform according to the direction so that the direction of the microwave electric axis is parallel to the direction of the target simulation direction.
5. The three-axis calibration method for the spaceborne microwave optical composite radar as claimed in claim 4, wherein the step 3 further comprises the following steps:
3.1, utilizing the first warp-weft instrument to perform auto-collimation with the antenna base prism, wherein the collimation direction is the X direction which is vertical to the plane direction of the antenna base and is used as the coordinate system of the antenna base prism;
3.2, utilizing the second theodolite to perform auto-collimation with the antenna base prism, wherein the collimation direction is parallel to the ground plane direction and is used as the Y direction of the antenna base prism coordinate system;
3.3, determining the Z direction of the prism coordinate system of the antenna base by using a right-hand spiral rule;
3.4, respectively placing measuring heads of the laser tracker on the first theodolite and the second theodolite, and measuring the coordinates of the two theodolites;
step 3.5, moving the first warp-weft instrument for a certain distance under the condition of keeping the auto-collimation of the first warp-weft instrument, then placing a measuring head of the laser tracker on the first warp-weft instrument, and obtaining a coordinate again;
3.6, axially constructing an antenna base prism coordinate system by using the three coordinates and the three coordinates;
and 3.7, constructing the relation between the plane of the radar antenna and the prism coordinate system of the antenna base according to the measured plane coordinate system of the radar antenna and the relation between the prism coordinate system of the antenna base and the coordinate system of the laser tracker.
6. The three-axis calibration method for the spaceborne microwave optical composite radar as claimed in claim 5, wherein the step 4 further comprises the following steps:
step 4.1, controlling the target simulation two-dimensional scanning frame to enable the composite simulation front end to move a certain distance d along the direction of the target simulation plane, and calculating an angle theta of the composite simulation front end as arctan (d/l) according to the distance; wherein l is the distance from the target plane to the antenna plane;
and 4.2, controlling the composite radar to track the target in a microwave mode, and measuring the feedback angle of the mechanism at the moment after stable tracking
Recording a target simulation angle theta; repeating the operation to obtain multiple groups of measurement data;
step 4.3, using a plurality of groups of measurement data, using theta as an independent variable and using thetaMechanism，
The data each construct a linear function θMechanism＝kMechanismθ+ΔθMechanism，
Wherein, Delta thetaMechanismThe angular difference between the mechanical axis and the microwave electric axis in the direction of the axis of the microwave electric axis is shown,
representing the angle difference between the mechanical axis and the microwave electric axis in the pitching direction of the microwave electric axis system;
determining by using a weighted least square iteration method when constructing a linear function;
step 4.4, kMechanismAnd
indicates that an angle exists between the azimuth direction of the mechanical axis system and the azimuth direction of the microwave electric axis system
The included angle of (A);
step 4.5, controlling the radar mechanism to keep the radar mechanism at a zero position by using radar measurement and control equipment, controlling a target to simulate a two-dimensional scanning frame, moving the composite simulation front end by a certain distance d along the Y direction, and calculating an angle theta (arctan (d/l)) of the composite simulation front end according to the distance; determining the rotation angle of the composite simulation front end to be theta by matching the two theodolites;
and 4.6, controlling the composite radar to track the target in an optical mode, and recording the target angle measured in the optical mode of the composite radar at the moment after stable tracking
Recording a target simulation angle theta; repeating the operation to obtain multiple groups of measurement data;
step 4.7, using a plurality of groups of measurement data, using theta as an independent variable and using thetaLight (es)，
The data each construct a linear function θLight (es)＝kLight (es)θ+ΔθLight (es)，
Wherein, Delta thetaLight (es)The angular difference between the visible light axis and the microwave electric axis in the direction of the microwave electric axis is shown,
representing the angle difference between the visible light axis and the microwave electric axis in the pitching direction of the microwave electric axis system;
determining by using a weighted least square iteration method when constructing a linear function;
klight (es)And
the angle between the azimuth direction of the visible optical axis and the azimuth direction of the microwave optical axis is shown as
The included angle of (a).
7. The method for calibrating three axes of a space-borne microwave optical composite radar according to claim 6, wherein the step 5 further comprises the following steps:
step 5.1, calibrating a microwave pitching shafting; rotating the system by 90 degrees, repeating the steps 1-4, completing the calibration of the pitching direction of the system, and determining the non-perpendicularity of the azimuth direction and the pitching direction of the microwave electric axis system according to the calibration result;
step 5.2, correcting the measurement result according to the calibration result; and correcting the measurement result into a microwave electric axis system according to the calibration result, and finally correcting the calibration result into an antenna base prism coordinate system according to the relation between the radar antenna plane and the antenna base prism coordinate system.
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