The drag-free satellites are widely used in the field of fundamental science as they enable the high-precision measurement in pure gravity fields. This paper investigates the estimation of local orbital reference fram...The drag-free satellites are widely used in the field of fundamental science as they enable the high-precision measurement in pure gravity fields. This paper investigates the estimation of local orbital reference frame(LORF) for drag-free satellites. An approach, taking account of the combination of the minimum estimation error and power spectral density(PSD) constraint in frequency domain, is proposed. Firstly, the relationship between eigenvalues of estimator and transfer function is built to analyze the suppression and amplification effect on input signals and obtain the eigenvalue range. Secondly, an optimization model for state estimator design with minimum estimation error in time domain and PSD constraint in frequency domain is established. It is solved by the sequential quadratic programming(SQP) algorithm. Finally, the orbital reference frame estimation of low-earth-orbit satellite is taken as an example, and the estimator of minimum variance with PSD constraint is designed and analyzed using the method proposed in this paper.展开更多
调制传递函数(modulation transfer function,MTF)检测是评价空间相机像质的重要手段.空间相机光学系统透过率和色差、探测器量子效率均与波长相关,采用不同光谱特征的光源所得到的MTF会出现偏差,光源光谱特性的影响不可忽略.针对这一问...调制传递函数(modulation transfer function,MTF)检测是评价空间相机像质的重要手段.空间相机光学系统透过率和色差、探测器量子效率均与波长相关,采用不同光谱特征的光源所得到的MTF会出现偏差,光源光谱特性的影响不可忽略.针对这一问题,提出了一种分析光源光谱特性对空间相机MTF检测结果影响的方法,设计了空间相机光谱响应率和单色PSF标定装置及方法.利用所提方法及标定结果,计算了五种光源检测空间相机MTF时的理论值,发现氙灯和其他四种光源的MTF值偏差较大.对比卤钨灯和氙灯检测MTF时的理论值,发现卤钨灯所得MTF在全频段内均大于氙灯所获取的MTF,二者之间的偏差在中高频处最大,最大偏差为0.075.搭建了实验装置,分别采用卤钨灯和氙灯作为光源,利用倾斜刃边法检测MTF,发现二者所得MTF在各个频率点处的分布特征及偏差与理论计算结果相同,且最大偏差为0.057.理论及实验结果表明,本文方法能够准确评估光源光谱特性对空间相机MTF检测的影响.展开更多
基金co-supported by the Open Fund of Joint Key Laboratory of Microsatellite of CAS (No. KFKT15SYS1)the Innovation Foundation of CAS (No. CXJJ-14-Q52)
文摘The drag-free satellites are widely used in the field of fundamental science as they enable the high-precision measurement in pure gravity fields. This paper investigates the estimation of local orbital reference frame(LORF) for drag-free satellites. An approach, taking account of the combination of the minimum estimation error and power spectral density(PSD) constraint in frequency domain, is proposed. Firstly, the relationship between eigenvalues of estimator and transfer function is built to analyze the suppression and amplification effect on input signals and obtain the eigenvalue range. Secondly, an optimization model for state estimator design with minimum estimation error in time domain and PSD constraint in frequency domain is established. It is solved by the sequential quadratic programming(SQP) algorithm. Finally, the orbital reference frame estimation of low-earth-orbit satellite is taken as an example, and the estimator of minimum variance with PSD constraint is designed and analyzed using the method proposed in this paper.
文摘调制传递函数(modulation transfer function,MTF)检测是评价空间相机像质的重要手段.空间相机光学系统透过率和色差、探测器量子效率均与波长相关,采用不同光谱特征的光源所得到的MTF会出现偏差,光源光谱特性的影响不可忽略.针对这一问题,提出了一种分析光源光谱特性对空间相机MTF检测结果影响的方法,设计了空间相机光谱响应率和单色PSF标定装置及方法.利用所提方法及标定结果,计算了五种光源检测空间相机MTF时的理论值,发现氙灯和其他四种光源的MTF值偏差较大.对比卤钨灯和氙灯检测MTF时的理论值,发现卤钨灯所得MTF在全频段内均大于氙灯所获取的MTF,二者之间的偏差在中高频处最大,最大偏差为0.075.搭建了实验装置,分别采用卤钨灯和氙灯作为光源,利用倾斜刃边法检测MTF,发现二者所得MTF在各个频率点处的分布特征及偏差与理论计算结果相同,且最大偏差为0.057.理论及实验结果表明,本文方法能够准确评估光源光谱特性对空间相机MTF检测的影响.
