浙江大学皮星二号实时精密自主定轨算法与半实物仿真

Precision Real-Time Orbit Determination Algorithm and Hardware-in-the-Loop Simulation for ZDPS-2 Satellite

本文研究了基于星载GPS的简化动力学实时精密自主定轨模型和算法,并将实时自主定轨软件应用于浙江大学皮星二号(ZDPS-2)在轨飞行任务中去。本文阐述了软件所采用的动力学模型、观测模型和估计算法框架,以及实现时所采取的可靠性设计方法。在此基础上,利用GRACE卫星GPS接收机在轨数据,对该自主研发的实时精密自主定轨软件进行了验证。结果表明:实时定轨位置精度在X、Y、Z三轴上的RMS(Root-Mean-Square)值分别为1.313 3 m、0.905 2 m、0.964 8 m,速度精度在X、Y、Z三轴上的RMS值分别为2.1 mm/s、1.2 mm/s、1.5 mm/s,接近国际研究水平。此外,基于皮星二号任务载荷-微型单频GPS接收机进行了半实物仿真试验。结果表明:定轨位置精度达到5 m左右,速度精度达到10 mm/s以内,与接收机自身定轨软件解算结果对比,定轨精度得到大幅提升,使其能满足一般皮纳卫星的应用需求。

The present study investigates the algorithm and prototype implementation of real-time reduced dynamic orbit determinationbased on a spaceborne GPS receiver,and the software of real-time orbit determination（RTOD） has applied to the mission of ZDPS-2. This paper describes the dynamic model of the spacecraft motion,the GPS measurement model,the estimation filter model,as well as the method to ensure the reliability of RTOD solution. Then,a simulative test has carried out to process spaceborne GPS flight data from the GRACE satellite using the RTOD software. This test demonstrates that the position accuracy（RMS）of the orbits in X,Y,Z axes is 1.313 3 m、0.905 2 m、0.964 8 m respectively and the velocity accuracy（RMS）in X,Y,Z axes is 2.1 mm/s、1.2 mm/s、1.5 mm/s respectively,which is comparable to the international level. Moreover,hardware-in-the-loop simulation has been performed for the ZDPS-2 satellite,making use of the single-frequency GPS receiver measurements. The results show that the RTOD solution is able to achieve the position accuracy（RMS）of about 5m and the velocity accuracy （RMS）of about 10 mm/s,meaning that the orbital accuracy is improved as compared to the single-point orbit solu？tion of the GPS receiver itself. So the RTOD algorithm and software can meet the requirement ofnano-satellite appli？cations like the ZDPS-2 satellite.