中文摘要：

利用X射线脉冲星观测量不仅能够为深空探测器提供稳定可靠的位置、速度和姿态信息,还能够对探测器上的原子钟进行长期误差校正。火星探测任务中,存在探测器飞行时间长,钟差随时间累积严重降低脉冲星自主定位系统的精度等问题。针对此,提出了一种环火探测器同步定位和授时方法,对钟差进行建模,将钟差模型参数纳入到滤波系统中,利用自适应扩展卡尔曼滤波器同时计算探测器的位置、速度和钟差模型参数。仿真实验表明,经滤波校正后的钟差保持在300ns以内,探测器的位置和速度精度分别优于200m和0.03m/s,精度得到明显改善。

英文摘要：

Measurement based on X-Ray Pulsars is not only able to provide stable and reliable position,velocity and attitude information for deep space probe,but also can correct the long term bias of the atomic clock in the probe.Especially for the Mars exploring missions,the flight time of Mars probe is fairly long so that the clock bias is accumulating continuously,which will greatly damage the accuracy of the Mars probe autonomous positioning and timing system.In this paper,a novel synchronous Positioning/Timing method for Mars probe is proposed based on the principle of synchronous positioning and timing by X-Ray pulsars.And the clock correction is modeled accordingly.Pulsar optimization factor is used to conduct the optimal selection of pulsars.Then the Positioning/Timing model is presented and the clock corrections based on the new clock model are estimated together with the position and velocity of the Mars probe by using the adaptive extended Kalman filter.So that the position,velocity and clock model parameters of Mars probe could be calculated synchronously.Simulation experiments are carried out based on the proposed method.Results show that the clock bias can maintain in300 ns,while the position and velocity accuracy of Mars probe is better than 200 mand 0.03m/s after corrected,respectively.Conclusions could be drawn that the proposed method of Mars Probe Autonomous Positioning and Timing Based on X-Ray Pulsars could overcome the initial state error effectively and obtain more accurate filter value of position,velocity and clock parameters for Mars probe.