某型飞机电动机构故障分析与预防

针对某型飞机电动机构故障进行分析,查找导致故障的原因,并提出相应的解决措施,为后续开展此类故障分析提供一定的帮助和指导.     

PLC在交流伺服控制系统中的应用

目的为了满足工业生产对控制设备安全可靠性要求;方法通过分析PLC在自由端口模式通信方式下的工作原理,针对西门子S7-200型PLC与ACU串行通信中的难点,以利用其I/O端子采集状态信号进行天线交流控制系统应用为例;结果给出相关的程序设计流程图;结论提出一种有效可行的解决方案,获得良好的经济和运行效益。     

波音737NG飞机NGS系统

飞机燃油系统的防火防爆能力,直接关系到飞行安全,2008年7月,FAA发布了法规,要求飞机制造厂家必须提供必要的措施来降低全部或者部分位于机身内部燃油箱的可燃性。通过利用飞机自身的引气,将引气中的氧气浓度降低后再将引气送入中央油箱。结果降低油箱内空气中的氧气浓度,使油箱内氧气达到可燃浓度以下,防止油箱爆炸。NGS系统作为燃油箱惰化手段,有效保证了飞机的飞行安全。     

基于多层感知机的密封继电器PIND信号识别

设计了一套航天密封继电器信号识别方法，基于微粒碰撞噪声检测(PIND)法，通过对信号的时域及频域的特征分析选取了多个具有代表性的特征。运用了机器学习方法，采用多层感知机并对其进行超参数寻优，找到了最优的超参数组合。对信号进行处理分析来判断密封继电器内是否存在多余物。提高了分类的准确率，同时也提高了模型的整体性能。     

频率选择性衰落信道DS-CDMA无人机中继通信系统航迹规划

无人机中继通信是实现远距离无线通信的一种重要技术手段，无人机的飞行航迹对无人机中继通信系统的链路传输可靠性存在显著的影响，在频率选择性衰落信道环境下研究了基于直序列码分多址（DS-CDMA）的无人机中继通信系统的航迹优化的问题。首先，给出了基于DS-CDMA的译码转发无人机中继通信系统的模型，并理论分析给出无人机中继通信系统的链路中断概率及平均误码率计算公式，以此为基础，基于链路中断概率最小化准则提出了中继无人机的航迹规划方法，最后通过仿真验证了所提出方法的正确性与有效性。研究表明：最大比值合并DS-CDMA无人机中继通信系统可充分获取频率选择性衰落信道提供的分集增益，显著改善链路传输的可靠性。     

Multi-objective optimal formation reconfiguration with scalarization and stochastic boundaries

A new method is proposed for multi-objective optimal control of satellite formation reconfiguration. First, necessary optimality conditions of single-objective fuel-optimal reconfiguration are studied. Problem of initial guess of the costate and control discontinuity are addressed by using a new developed stochastic based method. Terminal conditions of Two Point Boundary Value Problem (TPBVP) of the optimal control equations are relaxed using augmented Gaussian. Variances or bandwidths of the terminal conditions are set to decision variables to be optimized. Responses of varied initial costate are modeled and propagated using Riccati equation. Using quadratic convolution of relaxed terminal conditions, objective function of the fuel-optimal problem is reformulated into a quadratic equation, and a gradient based optimizer is used to search the optimal initial guess. In the second part of the paper, optimal control of format flying reconfiguration with two competitive objectives:fuel and time of flight (ToF) is studied. With Pascoletti-Serafini scalarization, the Multi-objective Optimal Control Problem (MOCP) is scalarized into a set of weighted Single-objective Optimal Control Problems (SOCP). Hamiltonian and switch function for the weighted SOCP are developed and constructed. New developed stochastic based approach is then used to search the optimal Pareto solutions. Verification and performances of proposed algorithms are demonstrated through numerical simulations of single-objective and multi-objective optimal control of low-thrust elliptical orbit formation reconfiguration. Potential applications of the algorithms to some other preliminary space mission designs are also discussed.     

面向全月球探测的天基中继测控系统设计

中继测控是月球探测任务中必须解决的关键问题，特别是月球背面和两极地区的着陆和巡视探测任务以及载人登月任务。本文首先对国内外月球中继测控卫星的研究和发展情况进行了调研，分析了未来全月球探测对中继测控的需求。在此基础上，重点给出了面向全月球探测任务的天基中继测控系统设计方案，并仿真分析了该方案的中继测控性能。最后给出了简要的卫星设计方案。     

Finite-time relative orbit-attitude tracking control for multi-spacecraft with collision avoidance and changing network topologies

This paper addresses the relative position tracking and attitude synchronization control problem for spacecraft formation flying (SFF). Based on the derived relative coupled six-degree-of-freedom dynamics, a robust adaptive finite-time fast terminal sliding mode controller is proposed to achieve the desired formation in the presence of model uncertainties and external disturbances. It is shown that the designed controller is effective for changing information exchange topology making it robust to node failure. Then, the artificial potential function method is employed to generate collision avoidance schemes to modify the controller such that inter-agent collision avoidance can be ensured during the formation maneuver, which is critical for practical missions. The stability of the overall closed-loop system is proved by using Lyapunov theory. Finally, numerical examples for a given SFF scenario are presented to illustrate the performance of the controller.     

简析一起飞机转弯航向误差大的故障原因及预防措施

某型飞机装有两套HZX-1航向姿态系统，飞行中同时出现转弯航向误差大现象，本文通过分析故障原因，找出了引起故障的关键产品，并针对故障制定了预防措施。     

基于Radau伪谱方法的轨迹优化

研究了导弹在末制导阶段满足多约束条件下的轨迹优化问题。针对传统方法在处理复杂的非线性运动学、动力学约束上存在的困难,提出了一种基于Radau伪谱方法(RPM)的求解策略。首先,给出了考虑导弹速度和空气密度变化、终端和过程约束条件以及2种不同的性能指标函数的最优轨迹优化问题;其次,利用RPM将轨迹优化问题转化为非线性规划问题,采用序列二次规划算法求得最优解;最后,分2种初始条件对最大落角和最大终端速度的轨迹优化问题进行了仿真验证,结果表明:本文方法能够在较短的时间内生成一条满足多种约束要求的高精度的最优轨迹。