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R. Pail 《Journal of Geodesy》2005,79(4-5):231-241
In the recent design of the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite mission, the gravity gradients are defined in the gradiometer reference frame (GRF), which deviates from the actual flight direction (local orbit reference frame, LORF) by up to 3–4°. The main objective of this paper is to investigate the effect of uncertainties in the knowledge of the gradiometer orientation due to attitude reconstitution errors on the gravity field solution. In the framework of several numerical simulations, which are based on a realistic mission configuration, different scenarios are investigated, to provide the accuracy requirements of the orientation information. It turns out that orientation errors have to be seriously considered, because they may represent a significant error component of the gravity field solution. While in a realistic mission scenario (colored gradiometer noise) the gravity field solutions are quite insensitive to small orientation biases, random noise applied to the attitude information can have a considerable impact on the accuracy of the resolved gravity field models. 相似文献
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Calibrating the GOCE accelerations with star sensor data and a global gravity field model 总被引:1,自引:0,他引:1
A reliable and accurate gradiometer calibration is essential for the scientific return of the gravity field and steady-state
ocean circulation explorer (GOCE) mission. This paper describes a new method for external calibration of the GOCE gradiometer
accelerations. A global gravity field model in combination with star sensor quaternions is used to compute reference differential
accelerations, which may be used to estimate various combinations of gradiometer scale factors, internal gradiometer misalignments
and misalignments between star sensor and gradiometer. In many aspects, the new method is complementary to the GOCE in-flight
calibration. In contrast to the in-flight calibration, which requires a satellite-shaking phase, the new method uses data
from the nominal measurement phases. The results of a simulation study show that gradiometer scale factors can be estimated
on a weekly basis with accuracies better than 2 × 10−3 for the ultrasensitive and 10−2 for the less sensitive axes, which is compatible with the requirements of the gravity gradient error. Based on a 58-day data
set, scale factors are found that can reduce the errors of the in-flight-calibrated measurements. The elements of the complete
inverse calibration matrix, representing both the internal gradiometer misalignments and scale factors, can be estimated with
accuracies in general better than 10−3. 相似文献
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GOCE gradiometer: estimation of biases and scale factors of all six individual accelerometers by precise orbit determination 总被引:3,自引:0,他引:3
P. N. A. M. Visser 《Journal of Geodesy》2009,83(1):69-85
A method has been implemented and tested for estimating bias and scale factor parameters for all six individual accelerometers
that will fly on-board of GOCE and together form the so-called gradiometer. The method is based on inclusion of the individual
accelerometer observations in precise orbit determinations, opposed to the baseline method where so-called common-mode accelerometer
observations are used. The method was tested using simulated data from a detailed GOCE system simulator. It was found that
the observations taken by individual accelerometers need to be corrected for (1) local satellite gravity gradient (SGG), and
(2) rotational terms caused by centrifugal and angular accelerations, due to the fact that they are not located in the satellite’s
center of mass. For these corrections, use is made of a reference gravity field model. In addition, the rotational terms are
derived from on-board star tracker observations. With a perfect a priori gravity field model and with the estimation of not
only accelerometer biases but also accelerometer drifts, scale factors can be determined with an accuracy and stability better
than 0.01 for two of the three axes of each accelerometer, the exception being the axis pointing along the long axis of the
satellite (more or less coinciding with the flight direction) for which the scale factor estimates are unreliable. This axis
coincides with the axis of drag-free control, which results in a small variance of the signal to be calibrated and thus an
inaccurate determination of its scale factor in the presence of relatively large (colored) accelerometer observation errors.
In the presence of gravity field model errors, it was found that still an accuracy and stability of about 0.015 can be obtained
for the accelerometer scale factors by simultaneously estimating empirical accelerations. 相似文献
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GOCE卫星由于加速度计的特殊安装方式,其非保守力主要由普通模式的组合加速度提供,使得单个加速度计的特征更难提取.本文首次采用实测数据,研究了单加速度计模式下的高低跟踪数据处理.利用GOCE任务2009年(2009-11—2009-12)的实测数据,分别以GOCE卫星梯度仪坐标系三个坐标轴正向的加速度计为研究对象,利用1 s间隔的高采样轨道数据,采用动力法同时进行卫星重力场建模和加速度计的精密校准.为了克服两极地区的数据缺失对重力场模型低次系数的影响,即所谓的极空白问题,引入同期GRACE卫星的观测数据,采用方差分量估计方法,建立了GRACE/GOCE卫星跟踪卫星重力场模型WHU-GRGO-SST.该模型完全到100阶次,经6169个美国GPS水准点数据检验,在同阶次上与EGM2008和GGM05S的精度水平相同.分析发现,GOCE卫星的加速度计偏差参数存在显著的漂移,也显示了单加速度计模式处理GOCE高低跟踪数据的优势.本文的研究成果为建立静态高分辨率、高精度的GRACE/GOCE重力场模型提供了更严密的模型与技术方案,同时也为GOCE卫星梯度仪校准,以及梯度数据的深入分析提供了重要的参考信息. 相似文献
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Exploring the possibilities for star-tracker assisted calibration of the six individual GOCE accelerometers 总被引:1,自引:0,他引:1
P. N. A. M. Visser 《Journal of Geodesy》2008,82(10):591-600
A method has been developed and tested for estimating calibration parameters for the six accelerometers on board the Gravity
field and steady-state Ocean Circulation Explorer (GOCE) from star tracker observations. These six accelerometers are part
of the gradiometer, which is the prime instrument on board GOCE. It will be shown that by taking appropriate combinations
of observations collected by the accelerometers, by modeling acceleration terms caused by gravity gradients from an a priori
low-degree spherical harmonic expansion, and by modeling rotational acceleration terms derived from star-tracker observations,
scale factors of each of the accelerometers can be estimated for each axis. Simulated observations from a so-called end-to-end
simulator were used to test the method. This end-to-end simulator includes a detailed model of the GOCE satellite, its instruments
and instrument errors, and its environment. Results of the tests indicate that scale factors of all six accelerometers can
be determined with an accuracy of around 0.01 for all components on a daily basis. 相似文献
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