机载光电稳定平台的强鲁棒性滑模变结构控制

为使机载光电稳定平台系统在复杂环境下仍具有强鲁棒性,建立光电稳定平台数学模型.以两轴四框架光电吊舱为研究对象,通过分析噪声干扰及本身结构参数的变化对光电稳定平台的影响,提出基于干扰观测器(disturbance observer,DOB)的滑模控制器设计方案.理论推导和仿真结果表明:滑模变结构控制(sliding mode variable structure control,SMVSC)对干扰力矩和摄动完全适应,对系统结构参数变化和外界扰动具有良好的鲁棒性;比无干扰观测器的控制系统,拥有更高的稳定精度和更快的动态响应,能增强光电稳定平台的抗扰动能力.     

基于扰动观测器的机载光电稳定平台自适应指数时变滑模控制

针对考虑载机干扰、摩擦力矩和参数不确定性等扰动因素影响的机载光电稳定平台高精度控制问题,提出了一种基于非线性扰动观测器的自适应指数时变滑模控制方法。该方法利用非线性扰动观测器观测系统的聚合不确定性,用来抵消外界扰动和参数不确定性对系统的干扰。在此基础上,设计自适应指数时变滑模控制器,实现了光电稳定平台伺服系统在残余聚合扰动影响下的期望角位置转动的全局鲁棒控制,该方法不需要确定聚合不确定性的上界信息,同时避免了普通自适应滑模的切换增益过度自适应问题,最终通过李雅普诺夫稳定性定理证明了闭环系统的全局渐近稳定性,系统角位置最终渐近收敛到期望角位置。数值仿真和样机测试结果表明,在外界扰动和参数不确定性的影响下,该方法能够实现系统的高精度角位置控制。     

基于最优化的导弹伺服机构滑模变结构控制研究

针对导弹伺服机构，研究了基于最优化的滑模变结构控制方案。首先建立了导弹伺服机构模型，并用优化方式确定切换函数，用到达条件确定滑模变结构控制律。仿真表明：基于最优化方法设计的滑模变结构控制系统，对外部干扰和参数不确定性具有强的鲁棒性，优于传统控制方案。     

基于最优化的导弹伺服机构滑模变结构控制研究

针对导弹伺服机构,研究了基于最优化的滑模变结构控制方案.首先建立了导弹伺服机构模型,并用优化方式确定切换函数,用到达条件确定滑模变结构控制律.仿真表明:基于最优化方法设计的滑模变结构控制系统,对外部干扰和参数不确定性具有强的鲁棒性,优于传统控制方案.     

低速摩擦伺服系统的滑模变结构控制研究

针对低速摩擦伺服系统,提出采用指数趋近率的滑模控制方法,以保证运动点在有限时间到达平衡点,缩短了趋近时间.并且通过引入饱和函数以削弱抖振.最后运用Matlab/Simulink软件平台仿真,验证了该方法具有良好的跟踪特性和较强的鲁棒性.     

陀螺稳定平台伺服回路的变结构控制

针对陀螺稳定平台伺服回路模型, 设计了基于角加速度信号反馈的变结构控制器.理论及仿真研究结果表明, 变结构控制系统对平台受到的扰动力矩及参数变化具有完全的自适应性, 并可有效地克服变结构控制器的抖动性对系统的不利影响.由于系统设计从实际对象模型出发, 且控制算法简单、易实现, 可望获得工程应用.     

火箭炮交流位置伺服系统滑模变结构控制策略

对多管火箭炮负载特性，转动惯量变化规律及其燃气流冲击力矩作用规律进行了定量分析，基于此设计了多管火箭炮交流位置伺服系统结构并提出了滑模变结构控制策略，对其具体控制结构的形式进行了分析，提出了统一滑模变结构控制和串级滑模变结构控制两种方案。最后给出了两种滑模变结构控制结构的计算机仿真结果，结果表明该控制策略具有较强的抗负载扰动能力和参数鲁棒性，可以适应多管火箭炮的负载干扰力矩以及转动惯量的变化。     

陀螺稳定平台的滑膜变结构控制实验研究

针对高精度陀螺稳定平台快速隔离扰动、稳定视轴的要求,设计了以挠性陀螺为惯性传感器的双轴陀螺稳定平台.介绍了该平台的结构,分析了影响平台稳定精度的因素,并针对速率陀螺反馈加传统PID控制不能实现稳定角度无静差的问题,尝试了一种滑膜变结构控制策略.试验结果表明,采用滑膜变结构控制方法后,陀螺稳定平台精度可提高50％以上.     

基于滑模变结构控制的PMSM建模仿真

基于滑模变结构控制建立了永磁同步电机(PMSM)的数学模型,分析了在d轴电流等于零情况下的控制方法,并运用Simulink进行仿真,这对应用永磁同步电机作为动源的伺服系统的设计、制造和使用有一定的参考价值。     

基于LuGre模型的伺服转台自适应反演滑模控制

为降低摩擦力矩对机电伺服转台控制精度的影响,提出了自适应反演滑模控制方法;分析了伺服系统的原理,并应用LuGre模型对摩擦力矩进行了建模;在此基础上结合滑模控制和反演法,提出了自适应反演滑模控制(ABSM)算法;将ABSM控制器与原有的PID控制器进行了仿真对比实验。结果表明:所设计的控制器增强了系统的鲁棒性,大幅提高了控制精度。     

Stability of the Third Generation Intensifier under Illumination

The stability under illumination of transmission-mode GaAs photocathode sealed in the third generation intensifier is investigated by use of spectral response testing instruments. The variations of spectral response with the illumination times under weak and intense illumination are compared. The variations of photoemission performance parameters are also characterized. The results show that during initial several weak illuminations photocathode behaves no evident decay and a maximum sensitivity is achieved, while under intense illumination the sensitivity of photocathode begin to decrease largely at the first illumination. The calculated performance parameters show that the variation of surface escape probability with illumination times is a direct cause of instability of photocathode. It is also found that under intense illumination peak wavelength is moved towards short-wave and peak response is decreased, which shows that the ability of long-wave response of photocathode is decreased.     

Nitrosation and Nitration of Tetraacetyldibenzylhexaazaisowurtzitane

Tetraacetyldibenzylhitane (TADBIW) was subjected to debenzylation by nitrosating with inorganic materials available commercially to synthesize tetraacetyldinitrosohexaazaisowurtzitane (TADNSIW). TADNSIW was purified, and its structure was determined by FTIR, 1H NMR, MS and element analysis. The debenzylation reaction of TADBIW gave quantitative benzaldehyde as a by-product. This indicates that the reaction produces an imine cation as an intermediate. Hexanitrohexaazaisowurtzitane (HNIW) was prepared from unpurified TADNSIW with the yield over 96.0 % and the purity more than 98.0 %. And the mechanism of the reaction from TADNSIW to HNIW is proposed to be oxidation of nitroso and nitration of acetyl on the molecule of TADNSIW, This reaction system involved is simple, and the reaction can complete within a short time and under mild conditions. The product can be easily to separate and the waste disposed readily.     

Passive Acoustic Radar for Detecting Supersonic Cruise Missile

A Passive Acoustic Radar is presented as a necessary complement to electromagnetic wave radar, which will be expected to be an effective means for detecting cruise missiles. Acoustic characteristics of supersonic flying projectiles with diverse shapes are expounded via experiment. It is pointed out that simulation experiment could be implemented using bullet or shell instead of cruise missile. Based on theoretical analysis and experiment, the ““acoustic fingerprint““ character of cruise missile is illustrated to identify it in a strong noise environment. After establishing a locating mathematical model, the technique of acoustic embattling is utilized to resolve a problem of confirming the time of early-warning, considering the fact that velocity of sound is much slower than that of light. Thereby, a whole system of passive acoustic radar for detecting supersonic cruise missile is formed.     

A Robust Algorithm for Watermarking 2D Vector Maps with Low Shape-Distortions

The technique of watermarking has been introduced into 2D vector maps for many potential applications such as protecting the copyright of important GIS （geographical information system） data and tracing the data source of military maps. In most previous works, although the validity of the map data could be preserved during the embedding procedure, the shape-distortions of the map elements are usually neglected which would tend to degrade the invisibility of the watermarking schemes. A shape-preserving algorithm for watermarking 2D vector maps is presented in this paper. A 1D distance sequence extracted from the original map is adopted as the cover data instead of 2D coordinates. A watermark bit is represented by changing the distributions of the cover data. The embedding procedure induces lower shape-distortions than in former works. Experimental results indicate better invisibility of the proposed scheme, as well as its robustness to certain attacks such as map simplification, interpolation, additive noise and most geometric transforms.     

Design and Simulation of TF and TA Controller for Missile

A nonlinear terrain following(TF) and terrain avoidance(TA) controller is proposed for missile control systems. Based on classical TF algorithm (adaptive angle method), a new method for TF controller is proposed by using angle of attack. A method of obtaining terrain outline data from digital elevation map (DEM) for TF control is discussed in order to save store space. A TA algorithm is proposed by using bank-to-turn technique. The block control model, which is suitable for backstepping design, is given for nonlinear model of missile. Making full use of the characteristics of the system and combining block control principle and backstepping technique, a robust controller design method is proposed. Uncertainties in every sub-block are allowed, and can be canceled by using the idea of nonlinear damping. It is proved that the state tracking errors are converged to a neighborhood of the origin exponentially. Finally, nonlinear six-degree-of-freedom simulation results for the missile model are presented to demonstrate the effectiveness of the proposed control law.     

Super-resolution Restoration of Remote-sensing Images

A novel image restoration scheme, which is super-resolution image restoration algorithm Poisson-maximum-afterword-probability based on Markvo constraint （MPMAP） combined with evaluating image detail parameter D, has been proposed. The advantage of super-resolution algorithm MPMAP incorporated with parameter D lies in the fact that superresolution algorithm MPMAP model is discrete, which is in accordance with remote-sensing imaging model, and the algorithm MPMAP is proved applicable to linear and non-linear imaging models with a unique solution when noise is not severe. According to simulation experiments for practical images, super-resolution algorithm MPMAP can retain image details better than most of traditional restoration methods; at the same time, the proposed parameter D can help to identify real point spread function （PSF） value of degradation process. Processing result of practical remote-sensing images by MPMAP combined with parameter D are given, it illustrates that MPMAP restoration scheme combined PSF estimation has a better restoration result than that of Photoshop processing, based on the same original images. It is proved that the proposed scheme is helpful to offset the lack of resolution of the original remote-sensing images and has its extensive application foreground.     

Design and Analysis of Test Schemes of Static Postponing Time on Shrapnels Used to Riot Control

The test scheme of static postponing time given in our actual national military test standard on shrapnels used to control riot is a nine-point test scheme on the combined action of three kinds of temperatures and three kinds of pressures,the consumed ammunitions are more excessive. Statistic analysis and tentative checkout about a lot of test data are done,feasibility gists are put forward for optimizing of the test design scheme. The optimizing design and data analysis of test scheme of the item are done by managing uniformity design theory, two scientific and reasonable six-point test schemes are confirmed. The feasibility and reliability of the optimizing design schemes put forward above are proved ulteriorly by test validating. The gained schemes not only have good design uniformity and little ammunition wastage and meet the test demand, but also have better forecast ability for the result data of other points using the mathematic models from the actual test points.     

Research on Gear-broken Fault Diagnosis in a Tank Gearbox

A fault diagnosis method of working position gear in a tank gearbox is put forward based on simulating the fault of working position gear in an actual tank, extracting the envelope of vibration signal by Hilbert transformation amplitude demodulation method, and zooming the low-frequency band to envelope signal.     

Bistatic Sonar Localization Based on Best Linear Unbiased Estimation

A best linear unbiased estimation （BLUE） algorithm for bistatic sonar localization is proposed. The Cramer-Rao bound for bistatic Sonar and the geometrical dilution of precision （GDOP） in different conditions are given. The simulation results show that the location accuracy of BLUE algorithm is higher than the weighted least square method.