Event-triggered adaptive fuzzy attitude takeover control of spacecraft

The problem of attitude takeover control of spacecraft by using cellular satellites with limited communication, actuator faults and input saturation is investigated. In order to lighten the communication burden of cellular satellites, an event-triggered control strategy is adopted. The filtered attitude information needs to be transmitted only when the defined measurement error reaches the event-triggered threshold in this strategy. Then, to deal with the unknown inertia matrix, actuator faults, external disturbances and the errors caused by event-triggered scheme, fuzzy logic systems is introduced to estimate the uncertainties directly. Combining fuzzy logic control strategy and the event-triggered method, the first event-triggered adaptive fuzzy control law is developed. Then, torque saturation of cellular satellites is further considered in the second control law, where the upper bound of the uncertainties is estimated by fuzzy logic systems. The resulting closed-loop systems under the two control laws are guaranteed to be bounded. Finally, the effectiveness of two proposed control laws is verified by the numerical simulations.     

基于小波神经网络的无叶扩压器失速分析

用来自不同文献的实验数据作为样本,对小波神经网络进行训练,并利用训练好的神经网络研究叶轮和扩压器几何尺寸对无叶扩压器失速的影响.计算分析结果表明:几何尺寸对于宽、窄扩压器失速的影响表现不同,这也证明了不同宽度的扩压器的确存在不同的失速机理.文章的结果,对无叶扩压器的设计具有一定的借鉴意义.      

真空低温环境用大口径轻量化椭圆平反镜设计

文章介绍了真空低温环境用大口径轻量化椭圆平反镜的结构设计、轻量化设计。并针对椭圆平反镜的装卡特点、使用环境,利用有限元分析技术分析了椭圆平反镜在力载荷、温度载荷作用下的变形。根据计算结果和使用情况给出了反射镜的设计结论。     

基于PSOC的热变形与维卡软化点温度测控仪的设计

论文介绍了以一种基于PSOC微控制器的热变形与维卡软化点温度测控仪的设计,并对系统结构及功能实现中的一些具体问题进行了分析,实现了相关的硬件电路结构和完成相关功能的软件设计方案。     

卫星导航系统综合分析处理软件PANDA及研究进展

简要介绍了卫星导航系统综合处理软件卫星精密定轨定位综合分析软件（PANDA）的数据处理方法与策略,重点阐述了PANDA软件目前的新进展,并对PANDA软件的进一步的发展进行了讨论。软件目前的研究进展以及与国外研究水平的比较表明,PANDA软件具有很好的发展前景,可作为基础性研究的软件平台,可为我国自主导航系统及卫星应用项目的发展提供技术支持。     

基于直接反馈线性化的飞行器着陆控制设计

建立了飞行器六自由度非线性模型,采用直接反馈线性化方法和经典PID控制律设计方法对飞行器自动着陆下滑段进行控制器设计,将飞行器的任务转化为对飞行器舵面和油门的控制,并对所设计的控制系统进行了数字仿真,结果表明所设计的控制器能够满足飞行器着陆下滑段的控制要求。     

Experimental investigation of transient thermal behavior of an airship under different solar radiation and airflow conditions

Knowledge of the thermal behavior of airships is crucial to the development of airship technology. An experiment apparatus is constructed to investigate the thermal response characteristics of airships, and the transient temperature distributions of both hull and inner gas are obtained under the irradiation of a solar simulator and various airflow conditions. In the course of the research, the transient temperature change of the experimental airship is measured for four airflow speeds of 0 m/s (natural convection), 3.26 m/s, 5.5 m/s and 7.0 m/s, and two incident solar radiation values of 842.4 W/m² and 972.0 W/m². The results show that solar irradiation has significant influence on the airship hull and inner gas temperatures even if the airship stays in a ground airflow environment where the heat transfer is dominated by radiation and convection. The airflow around the airship is conducive to reduce the hull temperature and temperature nonuniformity. Transient thermal response of airships rapidly varies with time under solar radiation conditions and the hull temperature remains approximately constant in ∼5–10 min. Finally, a transient thermal model of airship is developed and the model is validated through comparison with the experimental data.     

奇异积分方程方法在接触压力分析中的应用

总结回顾了奇异积分方程的数值解法,对于第二类奇异积分方程使用分段连续函数法进行了求解;对于两个弹性体接触问题,通过接触体之间的滑移函数和间隙函数,建立求解接触压力的奇异积分方程.分别针对圆柱体与弹性半空间体、抛物线型压头与弹性半空间体、榫头与榫槽3类接触问题,确立奇异积分方程的具体表达式,而后使用分段连续函数方法进行求解,获得接触面上的接触压力.最后将计算所得的接触压力分别与理论解和有限元解进行了对比.对于圆柱体与弹性半空间体接触问题,奇异积分方程法的最大接触压力与理论解和有限元解的相对误差分别为0.3%和0.5%;对于榫头与榫槽接触问题,奇异积分方程方法计算所得的最大接触压力与有限元解的相对误差为1.8%,验证了奇异积分方程方法的有效性.      

电动汽车牵引用永磁同步电机的场路联合仿真

基于Maxwell 2D和Simplorer联合仿真平台,以1台额定功率20 kW的电动汽车牵引用永磁同步电机为研究对象,建立考虑电机饱和问题和损耗影响的电机牵引系统仿真模型。通过分析恒转矩工作区间id=0控制与MTPA控制、高速运行区间id=0控制与弱磁控制的牵引特性,具体对比了电机的磁链、电流、转矩脉动、驱动效率等特性。通过试验测试,验证了仿真方法的正确性,为电动汽车牵引电机调速系统的控制仿真提供了参考。     

基于分数阶傅里叶变换的GNSS接收机抗线性调频干扰技术研究

研究了分数阶傅里叶变换(Fractional Fourier Transform,FRFT)抗线性调频(Linear Frequency Modulation,LFM)干扰技术,提出了一种基于FRFT域幅度一阶矩的逐精度求取最佳变换阶次的方法,并针对连续LFM干扰提出了一种求取最佳变换阶次的策略。同时针对全球导航卫星系统(Global Navigation Satellite System,GNSS)中的LFM干扰,对信号的预处理、阈值的自适应选取做了研究与分析,给出了相应的处理方法。仿真结果表明,该方法能够减少抗连续LFM干扰时求取最佳变换阶次的计算量,而且可以有效抑制GNSS接收机中的LFM干扰。