椭圆轨道编队常值推力构形变化控制方法

采用T-H方程作为椭圆轨道编队的动力学描述，推导了常值推力作用下的椭圆轨道编队的构形变化控制方法。通过合理的选择控制量的作用时刻，可达到大量节约燃料的目的。结合该构形控制方法给出了燃料均衡与燃料最优的解决方案；最后，给出的仿真算例说明了本文设计方法的有效性。     

任意偏心率卫星的大气阻力的短周期摄动

通过本文采用的计算方法和CIRA 1972在160～2000公里高度围范的大气密度的分析模型,导出了人造地球卫星大气阻力短周期摄动的一种计算公式,它形式简单,收敛性好,适用于任意偏心率的卫星。     

压气机叶轮偏心引起的自激力和稳定性的实验研究

本文介绍了新建的单级压气机叶轮偏心旋转引起的失稳力和稳定性实验器和在该设备上进行的静、动态Alford力和稳定性实验研究。实验与理论分析结果有良好的一致性。      

基于蒙特卡罗方法的小卫星偏心分离动力学分析

对小卫星单星偏心分离动力学进行了研究。建立了基于多体动力学理论的偏心在轨分离模型,用ADAMS平台对小卫星分离过程动力学进行仿真,结果显示两者误差小于0.15%,验证了仿真模型的正确性。用Monte-Carlo法对分离动力学性能进行了优化,分析了不同因素对分离角速度和分离速度的敏感度,给出了三种优化方案。     

航天员舱外相对航天器运动轨迹摄动研究

用轨道根数描述载人航天器运动,在其轨道坐标系(LVLH)中,建立了含地球J2项引力和大气阻力摄动加速度的航天员质心相对航天器的运动模型。在参考轨道存在小偏心率时,对基于圆参考轨道假设推导的航天器编队飞行的线性时变系统状态矩阵进行了修正。仿真结果表明:对偏心率为0.002的航天器轨道,修正后模型所得航天员相对轨迹摄动量在离舱300 s后达到0.8%,是修正前模型的5倍,但计算量增加不超过5%,更适于航天员舱外飞行和近距离编队飞行建模。     

Cubature Kalman filtering for relative spacecraft attitude and position estimation

A novel relative spacecraft attitude and position estimation approach based on cubature Kalman filter is derived. The integrated sensor suit comprises the gyro sensors on each spacecraft and a vision-based navigation system on the deputy spacecraft. In the traditional algorithm, an assumption that the chief?s body frame coincides with its Local Vertical Local Horizontal (LVLH) frame is made to construct the line-of-sight observations for convenience. To solve this problem, two relative quaternions that map the chief?s LVLH frame to the deputy and chief body frames are involved. The general relative equations of motion for eccentric orbits are used to describe the positional dynamics. The implementation equations for the cubature Kalman filter are derived. Simulation results indicate that the proposed filter provides more accurate estimates of relative attitude and position over than the extended Kalman filter.     

压气机叶轮偏心引起的自激力和稳定性的理论分析

分析了轴流压气机叶轮偏心旋转时引起失稳力的机理、计算方法、转子失稳特性及稳定性边界等。结果表明, 压气机叶轮偏心旋转引起的自激力是推动转子反进动的, 因而可造成压气机转子反进动失稳。失稳是在一阶临界转速以上发生, 其特征是除有转速频率的振动外, 出现一阶反同步进动固有频率的振动, 合成非协调进动。失稳门坎值取决于叶轮的负荷和转速。      

电极摇动对微细电火花加工微孔深径比的影响

微细电火花具备加工任何导电材料和大深径比微孔的能力。但是随着孔深度的增加,气泡和加工屑很难排出孔外,导致频繁的非正常放电,从而使得电火花常规放电状态下微孔的深径比有限,然而电极摇动可以为电火花狭小放电间隙提供一个非均匀的流场,提高了排屑能力,这有助于提高微孔的深径比。着重研究微孔加工在去离子水和油两种介质下,电极摇动参数和电参数对微孔深径比的影响。试验结果表明:电火花常规放电状态下微孔的深径比随着摇动半径和电容的增加而增加,摇动速度对微孔深径比则没有明显的影响,这为实际生产中加工大深径比微孔提供了参考依据。     

New design of a compact aero-robotic drilling end effector: An experimental analysis

This paper presents the development of a normal adjustment cell (NAC) in aero-robotic drilling to improve the quality of vertical drilling, by using an intelligent double-eccentric disk nor-mal adjustment mechanism (2-EDNA), a spherical plain bearing and a floating compress module with sensors. After the surface normal vector is calculated based on the laser sensors’ feedback, the 2-EDNA concept is conceived specifically to address the deviation of the spindle from the sur-face normal at the drilling point. Following the angle calculation, depending on the actual initial position, two precise eccentric disks (PEDs) with an identical eccentric radius are used to rotate with the appropriate angles using two high-resolution DC servomotors. The two PEDs will carry the spindle to coincide with the surface normal, keeping the vertex of the drill bit still to avoid repeated adjustment and position compensation. A series of experiments was conducted on an aeronautical drilling robot platform with a precise NAC. The effect of normal adjustment on bore diameter, dril-ling force, burr size, drilling heat, and tool wear was analyzed. The results validate that using the NAC in robotic drilling results in greatly improved vertical drilling quality and is attainable in terms of intelligence and accuracy.