Design and analysis of truss deployable antenna mechanism based on a novel symmetric hexagonal profile division method

As the deployment, supporting, and stability mechanisms of satellite antennas, space-deployable mechanisms play a key role in the field of aerospace. In order to design truss deployable antenna supporting mechanisms with large folding rate, high accuracy, easy deployment and strong stability, aiming at the geometric division of the parabolic reflector, a novel method based on symmetric hexagonal division and its corresponding modular truss deployable antenna mechanism is proposed, and the original method based on asymmetric triangular division and its corresponding mechanisms are presented for comparative analysis. Then, the screw theory is employed to analyze the mobility of different mechanisms. Furthermore, the improved three-dimensional mesh method is used to divide the reflector surface of a large parabolic antenna designed by the two different methods, and the profile accuracy and the type of links are taken as the evaluation indexes to quantitatively analyze the division results. Finally, a three-dimensional model of the modular deployable mechanism based on the symmetric hexagonal design is developed, and the deployable mechanisms with different configurations based on the two design methods are compared and analyzed from the mechanical perspective. The research results provide a good theoretical reference for the design of deployable truss antenna mechanisms and their application in the aerospace field.     

机载天线及其布局设计要求

结合机载天线的实际工程应用,从载机平台物理性能、任务系统功能要求、天线方向图覆盖以及系统电磁兼容性等几个方面对如何合理地设计天线布局进行了分析;列举了一些任务系统天线的最优布局位置,进一步说明了合理的天线布局是载机平台的物理性能和系统电气性能的折衷结果,并针对未来机载天线的发展趋势提出了一些看法。     

紧缩场超高频(UHF)天线测试方法的研究

针对CCR120／100紧缩场超高频（UHF）天线测试的问题,根据紧缩场的现有条件,给出了利用紧缩场进行UHF天线辐射特性测试的方法,以及进一步提高测试精度的方法,以满足卫星UHF频段天线辐射特性测试的需求。     

A variational Bayesian-based robust adaptive filtering for precise point positioning using undifferenced and uncombined observations

In the application of precise point positioning (PPP), especially in the dynamic mode, the classical Kalman filter (KF) usually produces a large number of estimation errors or diverges when there are gross errors in the observation data or unexpected turbulences occur in target motion state or both of them. For such problem, a variational Bayesian (VB)-based robust adaptive Kalman filtering (VB-RAKF) is proposed in this paper. This filter introduces a classification robust equivalent weight function to resist observation gross error and the inverse Wishart prior to model inaccurate process noise covariance matrix (PNCM). To improve the instantaneous accuracy of state estimation, the VB approach is used to obtain better estimations of inaccurate PNCM. Several sets of observation data collected by IGS reference stations and vehicles are employed to check the robustness and positioning accuracy of the VB-RAKF model. The results show that the VB-RAKF algorithm is more robust than the KF, and can effectively resist the gross error in observation data and control state disturbance. In the IGS reference station tests, when compared to the KF, the static positioning accuracies of the VB-RAKF in the north, east and up directions are improved by 13%, 8% and 22%, respectively, and the simulated dynamic positioning accuracies of the VB-RAKF in the north, east and up directions are improved by 19%, 9% and 21%, respectively. The in-vehicle dynamic test verifies that the VB-RAKF outperforms the KF, and shows that the VB-RAKF has better performance than the KF when dealing with observation data which has obvious gross errors, and similar performance as the KF when gross errors are small.     

一种适用于气动优化的高效自适应全局优化方法

随着设计空间的增大和优化问题非线性程度的提高，基于代理模型的优化（SBO）过程收敛越来越慢，并且在局部勘测上呈现不足。本文发展了一种高效自适应全局优化方法，在整个样本细化迭代过程中采用变设计空间取样：即在每一步样本细化迭代过程中，利用当前设计空间中的样本建立代理模型，并且根据样本的内部特征，利用模糊聚类算法将该设计空间分割成几个子空间，然后在每个子空间内通过最大化目标函数的期望提高函数和最小化模型预测目标来增加新的样本，之后对子空间进行融合更新设计空间。6个解析测试算例的结果表明，所发展的方法相比于一般的代理模型优化方法，具有更好的鲁棒性以及全局探索和局部勘测能力，更适用于具有强非线性和多极值的优化问题。RAE2822气动优化实例表明，所发展的方法在处理工程实际问题时，仍然能够保持很好的效率、鲁棒性和自适应性。     

基于输入解耦特征模型的四足机器人运动控制

摘要： 针对四足机器人腿部关节控制和转弯步态规划问题，建立四足机器人单腿动力学模型，分析其多输入多输出、时变、耦合和非线性等特性，建立并推导一种具有输入解耦形式的多输入输出特征模型；在此基础上设计由多变量黄金分割自适应控制律和微分控制律组成的控制器；其次提出一种对角转弯步态，通过修正左右腿的迈步步长实现机器人的转弯，进一步分析步长修正量与转弯半径的关系；最后通过虚拟样机技术，分别进行机器人零负载和50 kg负载情况下的直行和转弯步态仿真，仿真结果验证所提方法的有效性.     

Fixed-time adaptive model reference sliding mode control for an air-to-ground missile

This paper addresses the fixed-time adaptive model reference sliding mode control for an air-to-ground missile associated with large speed ranges, mismatched disturbances and un-modeled dynamics. Firstly, a sliding mode surface is developed by the tracking error of the state equation and the model reference state equation with respect to the air-to-ground missile. More specifically,a novel fixed-time adaptive reaching law is presented. Subsequently, the mismatched disturbances and the un-modeled dynamics are treated as the model errors of the state equation. These model errors are estimated by means of a fixed-time disturbance observer, and they are also utilized to compensate the proposed controller. Therefore, the fixed-time controller is obtained by an adaptive reaching law and a fixed-time disturbance observer. Closed-loop stability of the proposed controller is established. Finally, simulation results including Monte Carlo simulations, nonlinear six-DegreeOf-Freedom(6-DOF) simulations and different ranges are presented to demonstrate the efficacy of the proposed control scheme.     

面向GPU快速处理的地面材质数据压缩方法 陆巍巍 1,徐涛2,徐珂文 1

为解决雷达图像仿真中海量地面材质数据的存储和加载问题,采用基于自适应最大行程长度编码和修正 偶对的压缩算法进行材质数据的压缩,从而有效地减少了数据的存储量,消除数据传输的瓶颈,提高了数据传输的 吞吐能力。压缩算法面向 GPU快速处理,得到压缩数据适用于 GPU进行快速解压。     

Robust adaptive filtering method for SINS/SAR integrated navigation system

This paper presents a new robust adaptive filtering method for SINS/SAR (Strap-down Inertial Navigation System/Synthetic Aperture Radar) integrated navigation system. This method adopts the principle of robust estimation to adaptive filtering of observational data. A robust adaptive filter is developed to adaptively determine the covariance matrix of observation noise, and adaptively adjust the covariance matrix of system state noise according to the adaptive factor constructed based on predicted residuals. Experimental results and comparison analysis demonstrate that the proposed method cannot only effectively resist disturbances due to system state noise and observation noise, but it can also achieve higher accuracy than the adaptive Kalman filtering method.     

一种天线主面分瓣连接件的设计

设计了一种天线主面分瓣连接件,介绍了该装置的工作原理及工作过程,通过分析、比较,表明该装置动作明确、定位简单准确且夹紧可靠,是一种较好的设计.