偏流角是影响线阵CCD相机推扫成像性能的重要因素。为实现在轨有限计算资源环境下偏流角的快速计算,根据圆轨道卫星飞行与地物随地球自转的速度矢量运动关系,建立了适用于圆轨道正视与前后视成像的偏流角模型,给出卫星飞行过程中星下点相对地物的运动速度矢量作角向振动的数学表达式。根据该模型提出基于旋转CCD方式的偏流实时补偿方案,并搭建偏流校正成像模拟平台进行了实验验证。仿真和实验表明,速度矢量模型具有更高的计算效率,计算精度和稳定性与坐标变换模型和轨道要素模型一致,能够将偏流导致的图像MTF下降抑制到5%。该方案适用于TDICCD相机与三线阵CCD立体测绘相机的偏流实时调整机构开发工作。
Drift angle is an important factor which disturbs image quality of linear array CCD camera in push broom imaging mode. In order to realize fast calculation to drift angle under limited computational resource condition on orbit, a drift angle expression applied to remote sensor with straight, forward and backward sight on circular orbit was constructed, based on character of relative motion between velocity of camera on round orbit and of ground target which moved with rotation of the earth. Mathematical expression of angular vibration of the velocity vector of satellite relative to target during satellite′s flight was given. The real-time adjusting method based on CCD rotating was presented and verified by constructing imaging testbed of real-time drift compensation. Simulation and test results indicate that speed vector model has higher calculation efficiency, and calculation accuracy and stability are as much as method of coordinate transformation and orbital element. MTF degradation can be suppressed to 5%with drift compensated by speed vector model. The method can be further used for development of drift angle real time adjustment mechanism of TDICCD camera and three-line CCD 3-D photography camera.