一种全局稳定的四旋翼无人机移动目标跟踪控制

针对地面目标机动不确定和风扰动条件下的四旋翼无人机目标跟踪问题,提出了一种全局稳定的控制策略。控制系统分为位置和姿态两个子系统。位置控制部分针对缺少目标与载机的相对速度问题,设计了输出有界的基于观测器的滑模控制器,且其输出能够保证所生成的期望姿态指令有界;设计了基于四元数的姿态控制器,通过增加非线性切换项,加快了动态跟踪速度,并得到了整个位置-姿态系统的稳定性证明。建立了风扰动模型,进行了目标机动情况下的跟踪飞行仿真,得到了满意的跟踪效果。     

跨音速飞行状态下的一种智能控制方法

讨论了跨音速段飞行状态下复杂的气动特性及其影响,为解决飞机飞行过程中纵向按速度静不稳定这一主要矛盾,设计了一种模糊神经网络控制器,控制器以角度跟踪误差及其微分信号为输入来控制相应的控制舵面,实现对姿态的跟踪控制;以速度跟踪误差及其微分信号为输入来控制油门的偏转,实现对速度的跟踪控制.在此基础上,进一步利用遗传算法对模糊神经网络控制器进行了优化设计,并给出了遗传算法各个参数的选取原则.仿真结果也验证了所设计的控制系统具有良好的性能.     

四旋翼无人机SO(3)快速终端滑模姿态控制器设计

为实现四旋翼大姿态角快速跟踪控制,在SO(3)空间中设计了一种非奇异快速终端滑模控制器,所设计的控制具有较为简洁的结构,避免了欧拉角姿态表示奇异及局部线性化的问题。改进的趋近律可加速系统远离滑模态的趋近速度且能有效去除抖振;通过Lyapunov稳定性理论对所设计的控制器进行了严格的稳定性证明;最后进行了姿态控制仿真,结果表明姿态跟踪迅速、精度高且抖振小。     

无人作战飞机自主攻击非线性控制器设计

针对无人作战飞机自主攻击过程高精度、大迎角以及飞行状态快速变化等飞行控制需求, 采用反步控制设计非线性控制器。依据飞行器六自由度方程建立非线性控制模型, 利用奇异摄动原理将速度控制器和姿态控制器设计分离开, 分别利用反步控制原理设计控制器, 采用一阶指令滤波器克服传统反步法带来的“微分爆炸”问题, 最后依据Lyapunov稳定原理证明了控制系统跟踪误差渐近趋近于零。仿真结果表明, 非线性控制器在输入参考信号发生剧烈变化时仍能够实现高精度跟踪控制。     

基于间接型迭代学习控制的四旋翼轨迹跟踪

针对反推控制方法在四旋翼飞行器轨迹跟踪中存在动态误差的问题,提出改善轨迹跟踪性能的间接迭代学习控制算法。首先将飞行器分为姿态和高度全驱动控制通道和水平轨迹欠驱动控制通道;然后基于反推控制方法分别设计了全驱动和欠驱动通道的稳定控制器,进而采用PID型迭代学习算法对反推控制器参考输入信号进行更新优化;最后,采用压缩映射原理和λ范数理论证明了算法的收敛性。仿真实验结果表明,PID型迭代学习律能够有效改善反推控制器的控制效果,实现对期望轨迹的完全跟踪。     

六旋翼飞行器建模及位置跟踪控制

为实现六旋翼的位置跟踪与控制功能,对六旋翼飞行器的数学模型进行了分析,通过线性化得到了其简单数学模型。在简化的数学模型基础之上设计了基于PID(比例-积分-微分控制器)控制算法的姿态控制器和位置控制器,控制器仿真结果表明位置跟踪误差小于2%。飞行实验中飞行器准确追踪给定的姿态角精度大于80%,飞行器性能稳定,实现方法合理。     

H∞回路成形直升机双回路控制系统设计

根据直升机飞行控制系统的内外回路设计概念,利用H∞回路成形方法设计了直升机双回路控制系统。首先采用H∞回路成形方法设计姿态命令/姿态保持控制器,使得直升机内回路具有良好的带宽和响应时间,且保持通道的解耦和鲁棒性;采用H∞回路成形方法构建直升机的速度回路作为外回路,实现对直升机的前飞速度和横向速度的控制,保证速度通道上具有良好的跟踪性能和鲁棒性能。并按照ADS-33E对所设计的控制系统的操纵品质做出了评价。仿真结果显示了良好的控制效果,验证了该设计方法的有效性。     

四旋翼飞行器双环条件积分滑模控制

针对存在阵风干扰及未建模特性下的四旋翼飞行器轨迹跟踪控制,基于非线性滑模控制技术,结合条件积分思想及Lyapunov稳定性理论设计了一种位姿双环条件积分滑模控制器.在获得四旋翼非线性动力学模型后对其进行线性化,简化被控对象数学模型,提高控制器设计效率.利用条件积分滑模控制律设计了位置环和姿态环的轨迹跟踪控制器,实现了控...     

四旋翼飞行器自稳定和轨迹跟踪控制研究

针对四旋翼飞行器自稳定飞行和轨迹跟踪控制问题,提出了一种多模态滑模姿态控制和新型回馈递推轨迹跟踪控制方法。首先,依据牛顿第二定律和欧拉方程建立了运动学方程,由于外环位置跟踪控制与内环姿态存在严重耦合,外环位置控制器采用新型回馈递推法设计,简单有效,同时降低了工程实现难度。其次,内环姿态控制根据多模态滑模设计理念,结合线性滑模和非奇异终端滑模特点设计了切换型滑模控制律,使得系统状态能够在最优模态下运行,同时保证系统的到达时间和滑动时间都是有限的,实现了全局快速收敛。最后,仿真实验数据表明所设计的控制器能够快速跟踪期望姿态和轨迹,具有较好的控制效果。     

两轴稳定平台的模糊-PID复合控制器设计与仿真

根据两轴光纤陀螺雷达天线稳定平台的工作要求,设计了经典PID稳定回路控制器和跟踪回路控制器,并设计了基于遗传算法的跟踪回路模糊控制器。针对两种位置控制器的不足,设计了模糊控制调整加权因子的模糊-PID复合控制器。仿真结果表明,采用复合控制器可以加快系统跟踪速度,提高系统强抗干扰能力,并能保持较高的跟踪精度。     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

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正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its