遥操作机器人神经网络Smith预估控制(英文)

针对遥操作机器人通讯通道中存在的时延 ,提出了一种神经网络 Smith预估控制方法。控制系统适合于时延不变但未知的情况。控制系统包括主控制器和从系统两部分。从系统采用动态神经网络辨识机器人的动态模型 ,神经网络权重在线学习 ,用神经网络的输出对非线性系统进行局部非线性补偿 ,将非线性系统线性化。主系统针对线性化的从系统 ,采用 Smith预估控制解决时延问题并保证系统的性能品质。通过李雅普诺夫稳定理论保证了时延控制系统的稳定性。对两关节机器人的仿真结果说明了该方法的有效性。     

A Generic Plug-and-Play Navigation Fusion Strategy for Land Vehicles in GNSS-Denied Environment

Achieving accurate navigation information by integrating multiple sensors is key to the safe operation of land vehicles in global navigation satellite system(GNSS)-denied environment. However,current multi-sensor fusion methods are based on stovepipe architecture,which is optimized with custom fusion strategy for specific sensors. Seeking to develop adaptable navigation that allows rapid integration of any combination of sensors to obtain robust and high-precision navigation solutions in GNSS-denied environment,we propose a generic plug-and-play fusion strategy to estimate land vehicle states. The proposed strategy can handle different sensors in a plug-and-play manner as sensors are abstracted and represented by generic models,which allows rapid reconfiguration whenever a sensor signal is additional or lost during operation. Relative estimations are fused with absolute sensors based on improved factor graph,which includes sensors' error parameters in the non-linear optimization process to conduct sensor online calibration. We evaluate the performance of our approach using a land vehicle equipped with a global positioning system(GPS) receiver as well as inertial measurement unit(IMU),camera,wireless sensor and odometer. GPS is not integrated into the system but treated as ground truth. Results are compared with the most common filtering-based fusion algorithm. It shows that our strategy can process low-quality input sources in a plug-and-play and robust manner and its performance outperforms filtering-based method in GNSS-denied environment.     

单元数字化机载雷达的自适应杂波对消

本文描述了用于大型单元数字化阵列雷达（EDAR）的多层自适应波束形成方法。各阵列单元的距离相关增益自适应（RDGA）提供了有效的杂波对消。机载截击（AI）雷达的模拟试验验证了这种方法的效率，并说明了它相对于阵列中随机相位误差和幅度误差的稳定性。     

Linear Shaped Charge Cutting Property and Charge Cutting Mechanism of Mg-Gd-Y-Zn Alloy

The linear shaped charge cutting technology is an effective technology for aircraft separation. It can separate invalid components from aircrafts timely to achieve light-weight. Magnesium alloy is the lightest metal material, and can be used to cast effective light-weight components of an aircraft construction. However, the application study of the linear shaped charge cutting technology on magnesium alloy components is basically blank. In response to the demand for the linear separation of magnesium alloys, the Mg-12Gd-0.5Y-0.4Zn alloy is selected to carry out the target shaped charge cutting test. The effects of the shaped charge line density, cutting thickness, and mechanical properties on the cutting performance of the alloy are studied. The shaped charge cutting mechanism is analyzed through the notch structure. The results show that the linear shaped charge cutting performance is significantly affected by the penetration and the collapse. The higher the linear density is, the stronger the ability of the linear shaped charge cutter is, and the greater the penetration depth is, which is advantageous. However, the target structure will be damaged when it is too large (e.g., 4.5 g?m-1). Within 12 mm, when the cutting thickness of the target increases, the penetration depth increases. The lower the tensile strength is, the greater the penetration depth is, and the more conducive the penetration depth to the shaped charge cutting is. When the elongation (EL) increases to 12%, the collapse of the target is incomplete and the target cannot be separated. When the tensile strength of the Mg-Gd-Y-Zn alloy is less than 350 MPa, the EL is less than 6.5%, the cutting thickness is less than 12 mm, and the linear shaped charge cutting of the magnesium alloy can be achieved stably.     

陷入财政困境中的航空公司前途未卜

作为恐怖袭击的后果之一，美国的民航业几乎财政瘫 痪。虽然联邦政府的一揽子援助措施会对其有所帮助，但至少有一或两家骨干航空公司可能破产。 不少于五家的航空公司被列入了“最危险（航空公司）”的名单，它们是ＡｉｒＴｒａｎ航空公司、美国西部航空公司、大陆航空公司、西北航空公司和合众国航空公司。这是依据它们的现金储备以及贷款能力来估算的。 其他因素还有赖于联邦政府援助华盛顿计划所批准的（资金）数量以及什么时候才可供使用，在未来的几周之内，会出现一个航空公司破产的高潮。另外一方面，那些占美国整个航空运输运力８…     

采用脉冲雷达数据鉴定导弹制导精度的最佳方法

一、引言——飞行试验鉴定概述为了有效地使用弹道式导弹,空军必须有效地鉴定其精度。为鉴定弹道导弹精度而制定的试验计划,随武器和负责部门的不同而不同,但一般都是地面试验和飞行试验相结合,然后加以分析。最能逼真模拟实战或预期运用情况的飞行试验计划,可按复杂性而分为两类。第一类试验通常称为验证性试验计划,其主要目的是测得武器系统的总误差,不注重分离各单项误差因素。第二类试验称为鉴定性试验计划,其目的是分离、鉴别和定量测定形成武器系统总误差的各主要误差源。这种飞行试验计划显然是最为复杂,因而实施起来也是最难成功的。而在洲际弹道式导弹比之用来鉴定其性能的基准系统更为精确的今天,尤为如此。本文详细讨论了在这种情况下鉴定惯性制导系统所遇到的问题,并介绍了一种分析方法,以此尽量减少其中一些问题所造成的影响。     

全球定位系统及其在航天器导航中的应用

洛克威尔国际公司为国防部研制的全球定位系统(GPS)的出现将开劈导航的新纪元。GPS用户可以以前所未有的高精度连续实时地在运载器上计算状态矢量(位置、速度和时间)。GPS卓越的性能为下列航天活动带来了很大好处,即航天器导航,卫星运送,实验定位,资源测绘,载荷部署和回收,推进剂节省,数据处理和航天任务规划。本文概述了GPS系统,介绍了一些确定低轨航天器GPS导航系统设计方案的用户系统参数,较详细地讨论了在航天飞机轨道器导航方面的具体应用,包括使用GPS系统能获得的预期好处。     

卫星自主导航——现状与历史

最近5—10年中,地球轨道卫星的自主操作已愈来愈受到人们的关注。星上计算系统的进展促进了这种设想的某些方面付诸实施。本文着重论述自主的一个方面——卫星导航。在卫星设计中实现这种功能就意味着星上能够实时测定航天器的位置和速度。自主导航就其本意而言,应不靠外部信号源而独立进行孚航;然而,这种严格定义可以有兼些变化,这样可能更现实。本文介绍了卫星导航的概念,着重阐述了该项技术发展过程中所做的一些重要工作。此外还讨论了通过各种飞行方案已经或正在研究的多种并存设计方案,并给出了各自的性能。对各种全自主导航系统进行了估价。全自主导航系统的定位精度为几公里,而采用部分自主导航的 GPS 系统却可达到几十米或更高的导航精度。还讨论了战略防御创新计划(SDI)这样的计划,被认为是需要未来自主导航的推动力,依此规划了一些能在近期内推进自主导航的研究活动。贯穿整个介绍和阐述,我们从公开文狱中引了一些参考文献,可供有志于深入研究和了解这一重要领域内前人所作贡献的人参考。