火星探测器减速着陆过程中若干问题的研究

Several Problems Relative with Descent and Landing Process of Mars Explorer

围绕火星探测器减速着陆过程中涉及的开伞控制技术、降落伞拉直过程的绳帆现象、降落伞充气性能以及物伞系统动力学特性等关键技术问题进行了研究。通过对探测器进入轨道的分析,提出了一种以动压为控制目标的自适应开伞控制方法,并对其原理和实现方法进行了研究。采用降落伞拉直过程多刚体、多质点、多自由度动力学模型,对绳帆现象进行了数值仿真分析,发现开伞攻角是绳帆现象的主要成因,并提出了设计控制措施。采用降落伞轴向-径向动量守恒充气模型研究了大气密度对降落伞充气性能的影响,得到了大气密度对降落伞充气时间、充气距离、充气过程中伞衣面积变化及开伞载荷的影响规律或特点。利用物伞系统动力学模型,研究了物伞系统减速下降过程的动力学特性。本文研究内容对于中国火星探测器减速着陆系统的工程设计、试验及性能评估等均具有较好的参考价值。

Some key technologies of Mars explorer during the descent and landing process are studied in this paper, including the parachute deployment control technology, the parachute line sail phenomenon of deployment process, the parachute inflation performance, and the dynamics characteristics of para- chute-payload system. By the entry trajectory analysis of Mars explorer, an adaptive parachute opening control method with a dynamic pressure as the control target is proposed, and its principle and realiza- tion method are studied. Using the multi-rigid-body, multi-degree-of-freedom and multi-particle dynam- ics model of parachute deployment process, the numerical simulation results on parachute line sail phe- nomenon are also analyzed. It is found that the main reason of line sail phenomenon is the attack angle of vehicle, and the design of control measures to avoid line sail phenomena is put forward. The influ- ences of atmosphere density on parachute inflation performance are investigated by the parachute infla-tion model of axial-radial momentum conversation. The regularities and characteristics of the atmos- pheric density on parachute inflation time, inflation distance, canopy project area, and opening load are obtained. Based on the dynamic model of the parachute-payload system, the dynamics characteristics of the parachute-payload system during the descent process in the Martian environment are studied. These research results are importantly valuable for engineering design, test and evaluating performance of the descent and landing system of Mars explorer in China.