Rod arm measurement and compensation method based on synthetic aperture radar (SAR) remote sensing imaging

Abstract

The invention relates to a rod arm measurement and compensation method based on synthetic aperture radar (SAR) remote sensing imaging. When remote sensing load motion error compensation is provided, errors of three grades of rod arms are required to be precisely measured, and error compensation is executed according to characteristics of the errors of the three grades of rod arms. The three grades of rod arms comprise a one-grade rod arm at a relative position of a global positioning system (GPS) antenna and an inertial measurement unit (IMU) sensing center, a two grades of rod arms at a relative position of the IMU sensing center and a remote sensing load phase center; and a size effect length from three accelerators to the IMU sensing center is calculated according to a structural size of IMU design. The rod arm measurement and compensation method has the characteristic that errors of positions, speed and attitudes and output errors of the accelerators which are caused by a rod arm effect error are eliminated; the motion measurement precision of a point of sale (POS) system is improved; and precise motion information of the remote sensing load phase center can be acquired, so that the remote sensing load imaging precision can be improved.

Description

technical field [0001] The invention relates to a lever arm measurement and compensation method based on SAR remote sensing imaging, which can be used to accurately measure size effects, primary lever arms, secondary lever arms and initial attitude arrays. Correct the harmful acceleration caused by the size effect, correct the position and velocity errors caused by the primary lever arm, and then correct the motion information output by the POS, correct the position, velocity, and acceleration errors caused by the secondary lever arm, and perform attitude conversion to Accurate SAR antenna phase center motion information is obtained. Background technique [0002] In aerial remote sensing, SAR imaging requires the carrier aircraft to perform ideal uniform linear translational motion. However, due to the influence of external forces such as atmospheric turbulence and flight control system deviation, the carrier aircraft deviates from the ideal trajectory, resulting in motion e...

AI Technical Summary

Problems solved by technology

[0004] The existing SAR compensation arm compensation scheme obtains the motion information of the SAR antenna center by compensating the first-level lever-arm error and the second-level lever-arm error between the IMU and GPS, without considering the size effect caused by the installation error inside the IMU error, and the determination method of the lever arm measurement and the initial installation attitude matrix is ​​not given

In addition, when compensating the first-stage lever arm, the lever arm component contained in the position error is not considered, resulting in measurement error

The existing methods have the following shortcomings: 1. When the carrier aircraft is performing high dynamic maneuvers, the harmful acceleration output by the accelerometer due to the size effect error reaches the level of 100 μg, which is equivalent to the accuracy of the accelerometer, especially for interferometric SAR imaging, which has a serious impact and must be compensated ; 2. The size effect of the accelerometer is not only related to its length, but also related to the direction of each accelerometer sensitive axis. There is an installation orientation error of the IMU relative to the carrier aircraft, which causes the direction of the accelerometer sensitive axis to change, so that the size effect error is introduced into the angular acceleration 3. There is no public report on how to determine the initial installation attitude of the IMU relative to the carrier aircraft and the initial installation attitude of the SAR antenna relative to the carrier aircraft; 4. For the primary lever arm, the existing The method only compensates the velocity error component, while the GPS receiver outputs position and velocity information at the same time, ignoring the first-order lever-arm error contained in the position observation will increase the position, velocity and attitude measurement errors;

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