火星探测器进入段导航问题研究

发布时间：2018-04-19 22:38

本文选题：自主导航 + 通信黑障　；参考：《北京理工大学》2016年硕士论文

【摘要】：未来的火星探测任务需要高精度的进入段导航能力。迄今为止,成功登陆火星表面的探测器在大气进入段都采用惯性导航方式,探测器的着陆误差在几百千米以上。同时,在“好奇号”进入过程中,经历了大约70秒的通信黑障时间。针对进入段可能出现的通信黑障现象,本文对进入段自主导航方案进行了研究。主要研究内容包括:首先利用牛顿力学定律,通过合理假设和近似,推导了进入段动力学三自由度和六自由度模型,目的是通过数值仿真软件计算出探测器标准飞行轨迹,为导航系统的仿真验证奠定基础。其次,通过热力学工具分析火星进入段大气的成分、温度、压强、密度以及其他参数信息,对驻点区和尾流区影响探测器通信的自由电子密度进行估计,采用Horton程序建立进入段通信黑障时间估计方法。估计通信黑障时通过建立激波方程分析了激波前后气体参数变化,并对“好奇号”的进入段过程出现的通信黑障进行了仿真验证。然后,针对探测器通信黑障以及惯性导航精度差问题,本文提出了基于三自由度动力学模型的IMU和轨道器组合导航方法。其中在IMU观测模型中,除了加速度观测模型外还建立了姿态观测模型。在轨道器观测模型中,详细建立了轨道器的运动方程,并对火星快车和火星勘测轨道器进行了轨道仿真。考虑在通信黑障情况下,本文对探测器的IMU和轨道器组合导航方法进行了仿真验证,分析了改进观测模型的有效性。最后,从通信信道的角度建立了火星进入段通信模型。通信信道模型由无线空间信道模型、等离子体衰减模型以及信号间歇观测模型三部分构成。其中将无线空间信道模型建立为Rice衰落模型,等离子体信道模型分析和计算了等离子体频率和碰撞频率对电磁波功率影响的定量关系,间歇观测模型建立了丢包率与信噪比的关系。最后提出了该通信模型下的UKF导航滤波算法,数值仿真验证了在该通信模型下IMU和无线电组合导航算法的有效性。
[Abstract]:The future Mars exploration mission requires high precision entry navigation capabilities. So far, the probes that have successfully landed on the Mars surface have used inertial navigation methods in the air entry section, and the landing error of the detector is more than a hundred kilometers. In the course of "curiosity", the time of communication blackout for about 70 seconds has been taken. The communication blackout phenomenon may appear in the entry section. This paper studies the autonomous navigation scheme of the entry section. The main contents include: first, using the Newtonian mechanics law, the three degree of freedom and six degree of freedom model of the entry segment dynamics are derived through reasonable assumptions and approximations. The aim is to calculate the detector standard through the numerical simulation software. The flight trajectory lays the foundation for the simulation of the navigation system. Secondly, the thermodynamic tools are used to analyze the composition, temperature, pressure, density and other parameters of the Mars into the atmosphere, and estimate the free electron density of the communication of the probe communication in the standing point and the wake region. The Horton program is used to estimate the time of the entry communication black barrier. To estimate the communication black barrier, the change of gas parameters before and after the shock wave is analyzed by the shock wave equation, and the communication black barrier appearing in the "curiosity" entry process is simulated. Then, in this paper, a IMU based on the three degree of freedom dynamic model is proposed to solve the problem of the communication black barrier and the poor precision of the inertial navigation system. In the IMU observation model, the attitude observation model is set up in addition to the acceleration observation model. In the orbiter observation model, the motion equations of the orbiter are set up in detail, and the orbit imitation of the Mars Express and the Mars Reconnaissance Orbiter is carried out. The IMU and the orbiter integrated navigation method has been simulated and verified, and the effectiveness of the improved observation model is analyzed. Finally, the communication model of the Mars entry section is established from the angle of communication channel. The communication channel model is composed of three parts: the wireless space channel model, the plasma attenuation model and the signal batch observation model. The linear space channel model is established as the Rice fading model. The plasma channel model analyses and calculates the quantitative relationship between the plasma frequency and the impact frequency on the electromagnetic wave power. The relationship between the packet loss rate and the signal to noise ratio is established by the intermittent observation model. Finally, the UKF navigation filtering algorithm under the communication model is proposed. The numerical simulation is verified by the numerical simulation. The effectiveness of IMU and radio integrated navigation algorithm under the communication model.

【学位授予单位】：北京理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：V476.4

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