多自由度伺服机构负载模拟系统建模与实验研究

针对运载火箭推力矢量伺服控制系统的负载模拟问题,分析了负载的多自由度特性,提出一种负载模拟系统结构并建立了数学模型.仿真结果表明,模拟系统中负载位置输出的动态特性与实际伺服机构负载的动态特性具有一致性.通过原理性实验,在负载的扫频实验中成功体现了负载的多自由度特性.仿真和实验结果证明了此种负载模拟原理的可行性.该负载模...     

双谐振点发动机推力矢量控制伺服机构算法优化研究

建立运载火箭双谐振点发动机的双质量弹簧物理模型,辨识特性参数,推导出伺服机构数学模型。采用直接数值寻优方法对推力矢量控制伺服机构算法进行计算优化研究,通过仿真分析和发动机冷摆试车试验,得出双陷波补偿是一种较优选择。     

伺服机构综合负载模拟试验系统

针对大型运载火箭伺服机构所受实际负载情况,提出了一种综合负载模拟系统,能够模拟惯性、弹性、摩擦和常值负载。其中惯性负载、弹性负载以及伺服机构的柔性安装基础采用机械结构模拟,摩擦负载和常值负载采用液压系统来实现。分别对伺服机构、液压加载系统以及柔性结构进行建模,并以此为基础构造了系统的综合数学模型。仿真表明,该系统能够复现伺服机构实际工况下的负载特性,加载多余力也能得到很好的抑制。建立了负载模拟试验系统,实现了对各种负载及谐振特性的模拟,为伺服机构的地面测试和深入研究提供必要的实验基础。     

火箭发动机喷管伺服机构负载模拟系统设计与实验

针对火箭发动机喷管伺服机构的半物理仿真需要,设计一种可对惯性负载、摩擦力矩负载、弹性力矩负载、伺服机构安装刚度进行模拟的电液负载模拟系统。依据伺服机构负载特点,由机械的方式实现惯性负载、摩擦负载以及安装刚度的模拟,由阀控伺服马达实现弹性力矩的模拟;分别建立伺服机构系统和马达加载系统的数学模型,并为马达加载系统设计基于速度前馈补偿和力矩前馈的控制系统;进行负载模拟器的现场实验,实验结果表明,各种加载负载满足精度要求,验证了负载模拟器设计的合理性和实用性,以及控制策略的有效性。     

运载火箭大功率多余度电静压伺服机构技术研究

针对新型运载火箭对大功率推力矢量控制的需求,提出了大功率多余度电静压伺服机构(Electro-Hydrostatic Actuators,EHA)技术方案,研制了双余度原理性样机进行技术验证。采用高集成一体化的模块化设计,伺服电机泵并联实现大功率输出,单个伺服电机泵满足基本摇摆功能,同时实现一度故障容错能力。建立了伺服系统控制模型,进行了数学仿真分析,完成了样机设计制造和大惯量负载试验研究,-45°相频带宽达到25.8rad/s,质量仅65kg,动态性能好,功重比高,验证了中国未来三或四余度等更高余度等级和更大功率级别的航天电静压伺服机构的技术可行性。     

矢量喷管伺服系统联合仿真与控制方案

针对矢量喷管位置伺服系统在实际运行过程中容易受到系统外部扰动导致参数不确定的问题,设计了基于软件接口的机电液系统联合仿真与控制方案,通过SolidWorks、ANSYS、ADAMS、EASY5和Simulink之间数据交换分别建立了矢量喷管伺服机构刚柔耦合动力学模型、液压系统动态模型和滑模控制器,并通过接口实现了矢量喷管位置伺服系统仿真模型的集成。仿真结果证明:采用自适应模糊滑模控制器有效克服了矢量喷管位置伺服系统参数不确定和非线性的影响,实现了对矢量喷管伺服机构的高精度控制。     

冗余技术在火箭推力矢量控制伺服系统中的应用

论述了一种用于火箭推力矢量控制系统中的三余度伺服机构,介绍了其工作原理,并对其者了数学仿真分析及试验验证。     

火箭炮位置跟踪双自由度反推控制方法

针对火箭炮负载变化范围大、发射扰动力矩强和跟踪精度要求高等特点,提出了一种双 自由度反推控制方法。根据伺服系统数学模型进行逆向递推,设计了控制律,利用自由度因子调整 控制参数,并通过Lyapunov 函数证明了闭环控制系统的稳定性。对系统外界干扰及参数摄动的位 置控制进行了仿真研究,并实验研究了系统调转、等速及正弦跟踪特性。仿真与实验结果表明,该 方法保证了系统的响应速度和控制精度,对负载扰动和参数摄动具有很强的鲁棒性。     

适应伺服机构卡死故障的控制指令重分配技术研究

提出一种能够适应运载火箭伺服机构卡死故障的控制指令重分配技术。在传统运载火箭控制系统设计过程中,伺服机构指令是在不考虑伺服机构故障时设计确定的,一旦伺服机构发生卡死故障将可能导致箭体姿态失稳。为了提高运载火箭的安全性和可靠性,根据某伺服机构卡死角度,通过控制指令在多个冗余伺服机构之间的重分配,在伺服机构卡死情况下仍能保证姿态稳定。仿真结果表明,即使某个伺服机构卡死也能保证姿态稳定,而且不需要重新设计控制参数。     

一种伺服机构模拟负载台多弹簧钢板统一设计方法

弹簧钢板是航天伺服机构负载台的重要组成部分,决定了负载台的负载特性。提出了一种伺服机构模拟负载台多弹簧钢板统一设计方法。相较传统方法,该方法可用于多钢板设计并拓展了其设计域。首先,以弹性力学矩形截面杆扭转的解析解为基础,定义了钢板扭转模型并提出修正系数的指数衰减函数形式的近似表达式;其次,提出多弹簧钢板设计的优化模型并给出确定优化初值的方法,该优化模型使目标函数和约束函数在全设计域二阶连续可微;最后,提出简化的钢板负载特性有限元校核方法,该方法可对不同宽厚比钢板扭转进行有限元建模和分析。分析结果表明:用工程案例对伺服机构模拟负载台多弹簧钢板统一设计方法进行检验,有效性得以验证。     

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.     

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.     

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.     

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 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.     

Design of Non-fragile Satisfactory Estimator for Linear Continuous Perturbed Stochastic Systems

The design problem of non-fragile estimator is addressed for a class of perturbed linear continuous systems. The perturbations occur on the plant and estimator parameters. The estimator designed should force the error system to achieve the desired decay rate and force the steady error variance less than the specified upper bound irrdevancy of the admissible plant perturbations and estimator perturbations. Consistency problem of the decay rate with the variance upper bound is first considered via linear matrix inequality （LMI） approach. The solution of the estimator parameter under specifications to be consistent is then discussed. The consistency condition of specifications and estimator parameter solution are transformed to feasible or minimum problems subject to a set of LMI respectively. The method is illustrated by a numerical example.     

An Improved Scene-based Nonuniformity Correction Algorithm for Infrared Focal Plane Arrays Using Neural Networks

The improved scene-based adaptive nonuniformity correction （NUC） algorithms using a neural network （NNT） approach for infrared image sequences are presented and analyzed. The retlna-like neural networks using steepest descent model was the first proposed infrared focal plane arrays （IRFPA） nonuniformity compensation method, which can perform parameter estimation of the sensors over time on a frame by frame basis. To increase the strength and the robustness of the NNT algorithm and to avoid the presence of ghosting artifacts, some optimization techniques, including momentum term, regularization factor and adaptive learning rate, were executed in the parameter learning process. In this paper, the local median filtering result of Xij （ n ） is proposed as an alternative value of desired network output of neuron Xij （ n ）, denoted as Tij （ n ）, which is the local spatial average of Xij （ n ） in traditional NNT methods. Noticeably, the NUC algorithm is inter-frame adaptive in nature and does not rely on any statistical assumptions on the scene data in the image sequence. Applications of this algorithm to the simulated video sequences and real infrared data taken with PV320 show that the correction results of image sequence are better than that of using original NNT approach, especially for the short-time image sequences （several hundred frames） subjected to the dense impulse noises with a number of dead or saturated pixels.     

Piecewise Filter of Infrared Image Based on Moment Theory

The disadvantages of IR images mostly include high noise, blurry edge and so on. The characteristics make the existent smoothing methods ineffective in preserving edge, To solve this problem, a piecewise moment filter （PMF） is put forward. By using moment and piecewise linear theory, the filter can preserve edge. Based on the statistical model of random noise, a related-coefficient method is presented to estimate the variance of noise. The edge region and model are then detected by the estimated variance. The expectation of first-order derivatives is used in getting the reliable offset of edge. At last, a fast moment filter of double-stair edge model is used to gain the piecewise smoothing results and reduce the calculation. The experimental result shows that the new method has a better capability than other methods in suppressing noise and preserving edge.     

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.     

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.