Reliable flight performance assessment of multirotor based on interacting multiple model particle filter and health degree

Multirotor has been applied to many military and civilian mission scenarios. From the perspective of reliability, it is difficult to ensure that multirotors do not generate hardware and software failures or performance anomalies during the flight process. These failures and anomalies may result in mission interruptions, crashes, and even threats to the lives and property of human beings. Thus, the study of flight reliability problems of multirotors is conductive to the development of the drone industry and has theoretical significance and engineering value. This paper proposes a reliable flight performance assessment method of multirotors based on an Interacting Multiple Model Particle Filter (IMMPF) algorithm and health degree as the performance indicator. First, the multirotor is modeled by the Stochastic Hybrid System (SHS) model, and the problem of reliable flight performance assessment is formulated. In order to solve the problem, the IMMPF algorithm is presented to estimate the real-time probability distribution of hybrid state of the established SHS-based multirotor model, since it can decrease estimation errors compared with the standard interacting multiple model algorithm based on extended Kalman filter. Then, the reliable flight performance is assessed with health degree based on the estimation result. Finally, a case study of a multirotor suffering from sensor anomalies is presented to validate the effectiveness of the proposed method.     

New design simulation for a high-altitude dual-balloon system to extend lifetime and improve floating performance

This paper presents a comprehensive simulation for a high-altitude dual-balloon system which consists of zero- and super-pressure balloons. Preliminary calculations were established to describe the basic concept of the new integrated system. A mathematical model was investigated to simulate the ascending and floating processes which considered the atmospheric conditions and thermodynamic variations. Based on the simulation, results showed that the floating altitude stability between daytime and nighttime was improved. This integrated system supports higher floating altitude levels than those of ordinary balloons and extends the lifetime of floating balloon systems. Moreover, results demonstrated that the integrated system was lighter than ordinary balloons, saving useful weight for effective payload. Furthermore, exploiting the advantages of both kinds of balloons while avoiding the difficulties was a significant goal in the current design to promote the floating performance of high-altitude balloons technology.     

一种尾流消散动态预测的改进算法

尾流间隔是增大跑道容量的主要限制因素之一，为了在保持安全水平的前提下有效地增大跑道容量，可以对尾流消散进行动态预测，并据此缩减尾流间隔。研究了一种尾涡消散动态预测算法，该算法考虑了真实大气的大气分层、湍流、侧风、迎面风、风切变以及地效影响，并用一阶后向差分对该算法进行了离散化改进；在改进算法的基础上，时进近阶段尾流的消散在Matlab中进行了仿真计算；计算结果复现了尾涡的下沉现象和侧风对尾涡传输的线性累积效应。     

A Structured Mesh Euler and Interactive Boundary Layer Method for Wing/Body Configurations

To compute transonic flows over a complex 3D aircraft configuration, a viscous/inviscid interaction method is developed by coupling an integral boundary-layer solver with an Eluer solver in a ＂semi-inverse＂ manner. For the turbulent boundary-layer, an integral method using Green＇s lag equation is coupled with the outer inviscid flow. A blowing velocity approach is used to simulate the displacement effects of the boundary layer. To predict the aerodynamic drag, it is developed a numerical technique called far-field method that is based on the momentum theorem, in which the total drag is divided into three component drags, i.e. viscous, induced and wave-formed. Consequently, it can provide more physical insight into the drag sources than the often-used surface integral technique. The drag decomposition can be achieved with help of the second law of thermodynamics, which implies that entropy increases and total pressure decreases only across shock wave along a streamline of an inviscid non-isentropic flow. This method has been applied to the DLR-F4 wing/body configuration showing results in good agreement with the wind tunnel data.     

区域运输规划模型系统

提出一种区域运输规划模型系统,以求从定量的角度,预测一个区域内的货物运输量,继而确定这些运输量对该区域内存在的多种运输方式的偏好结构,最后仿真这些运量在相应的各种运输网络上的分布情况,同时仿真模型还对运输网线路经过新建或扩建后所形成的新的运量分布进行模拟。根据运量分布情况,就可提出初步的规划建设方案。     

太阳能热推进系统效率分析

太阳能热推进采用小分子量气体作为推进剂可以获取800～900 s高比冲,但提高推进系统的换热效率是目前亟待解决的问题.本研究建立了太阳能热推进系统主要部件的基本分析模型,在利用有限单元法进行热分析的基础上,对系统在多种工况下的相关参数进行了计算,分析了各部件主要参数对提高太阳能热推进系统热效率和推进效率的影响,得出了系统效率在不同工作状态下的变化规律,并提出了提高系统效率的措施.     

温度对油—气式起落架缓冲性能的影响研究

油—气式缓冲器内部的油液特性及充气压力会随环境温度而变化,进而影响起落架的缓冲性能。为了探究温度对油—气式起落架缓冲性能的影响,在起落架落震试验的基础上,提出一种缓冲器环境温度模拟方法,并分析油—气式起落架缓冲器在20~80℃环境温度下的缓冲性能。结果表明：在所研究的温度范围内,缓冲器初始充气压力对温度变化敏感,随着温...     

一种高超声速滑翔飞行器轨迹智能预测方法

针对高超声速滑翔飞行器(Hypersonic glide vehicle, HGV)机动性强、轨迹预测困难的问题,选取气动加速度作为预测参数,提出了一种基于集合经验模态分解和注意力长短时记忆网络的HGV轨迹智能预测方法。首先,以HGV六自由度运动方程为基础,分析了其机动特性和气动力变化规律,建立了动力学跟踪模型,对气动加速度进行实时估计;其次,利用集合经验模态分解对估计的气动加速度进行分解和重构,减弱噪声影响,避免对预测模型的干扰;最后,利用去噪后的气动加速度数据对注意力长短时记忆网络进行训练,进而预测未来气动加速度数据并重构HGV未来轨迹,实现轨迹的在线预测。实验仿真表明,该方法能有效预测HGV机动轨迹,预测精度高、稳定性好。     

消光漆在光学系统的国内外应用

简单地列举了国内外一些消光漆的应用情况,阐述了消光漆的消光性能指标的测定方法,同时对

国内外的一些消光漆的消光性能进行了比较。

     

基于任务分析的飞行机组失误预测研究

在过去的20年内有多起严重事故由机组失误引起,采取措施防止或减少飞行机组失误成为降低航空事故率的关键.通过使用人误预测技术预测机组在执行飞行任务时的失误,寻找失误原因,进一步改进驾驶舱设计或增加培训来降低航空事故率是可行的方法.本研究以民航领域飞行安全需求为背景,在原有人误预测技术基础上,开发了基于任务分析的飞行机组失误预测模型,以某型飞机起飞任务为例,对飞行机组在操纵飞机起飞过程中可能发生的人误进行分析,实现了飞行机组失误的定性和定量预测.