DORIS系统自主在轨实时定轨的实现与精度分析

国家科技重大专项高分辨率空间对地观测项目的实施,对卫星平台的自主在轨实时定轨提出了新的需求.由法国发展的DORIS实时定轨系统虽已成功应用于多个对地观测平台,但该系统从未公布其原始数据和数据处理的技术细节,因此本文尝试利用DORIS地面主控站提供的ENVISAT标准格式多普勒数据,假设星上自主定轨时采用相同的数据,基于卡尔曼滤波算法实现(仿真)自主实时定轨.计算表明仅考虑简单的非球形引力模型,对于位置误差1km,速度误差1m/s的初始条件,2小时后滤波趋于稳定,滤波精度为十米量级,速度精度为厘米每秒级.为提高滤波计算效率,对坐标系统转换进行简化后,定轨精度仍在十米量级.基于DORIS仿真测量数据滤波计算表明,随着测量精度的提高和每圈观测弧段的增加,滤波计算的精度也会得到有效提高.

Realization and Accuracy Analysis of Real-Time Orbit Determination for DORIS System

The performance of National science and technology major project,namely high-resolution space Earth observation project,has raised a new demand for real-time orbit determination in order to serve effective management of Earth observation payload.DORIS system is one of the effective means for real-time orbit service in orbit and its onboard real time orbit determination system has successfully run on several payloads,yet its technical details have not been revealed.Real-time orbit determination is realized by using DORIS tracking data of ENVISAT based on Kalman-filter with a simplified dynamics model.The results show that,the filter algorithm tends to converge within 2 hours with a initial error of 1000m and 1m/s of position and velocity in three dimensions respectively,and reaches the accuracies of 10m for position and several centimeters per second for velocity.Moreover,coordinate transformation is simplified to improve the efficiency,only with little loss of accuracy.The simulation calculations also show that the accuracy of EKF improves effectively with improvement of measurement accuracy and increase of observation arcs.