快速反射镜扰动信号的模糊补偿控制

为了抑制扰动信号对快速反射镜系统输出性能的影响,保证快速反射镜结构特性改变后控制系统抑制扰动信号的能力,提出了一种对扰动信号进行模糊补偿的复合控制系统。系统中,模糊控制环节的输出参数同时用于整定PID控制参数和前馈环节控制参数,补偿系统因扰动造成的偏差,控制系统不需要增加额外的传感器,不会增加硬件系统的复杂性。利用频域分析方法,设计PID控制器的控制参数,进而设计模糊控制的规则。最后,对这种控制系统进行了仿真实验分析,结果表明:快速反射镜的结构参数变化前后,扰动模糊补偿控制系统对系统中的扰动信号均具有较高的抑制能力。     

导引头稳定系统隔离度研究

针对导引头稳定系统的扰动隔离度问题进行了深入研究,介绍了扰动隔离度的概念及相关数学模型,讨论了影响隔离度的各种因素,分析了弹体扰动作用的本质和摩擦力矩的关系,最后就探测器处理延迟对扰动隔离度的影响进行了全面的分析研究,并提出了一种基于Smith预估器的延迟影响补偿控制方案,通过仿真说明了该方法的有效性。     

雷达

TN95 2003051564荃于广义Kalman估计的机旅翻达高精度控制系统/张国峰,吉英存(北京航空航天大学)刀航空学报一2003,24(2)一160一162研究了在某型现役机载雷达系统中,采用广义Kalman建波器方法来预估目标机的俯仰角和方位角,产生跟踪目标用的雷达夭线驱动信号,替代传统的速率陀螺侧量元件来补偿本机机动所造成的扰动的方法,同时对探侧信号本身所具有的延迟起到了补偿作用.对目标的运动采用直角坐标系中的Si鳍er模型描述,而对侧量信号则是应用极坐标系中的描述,采用广义Kalm柳滤波器来完成估计,即在每一步的估计和控制中对计算测量方程进行…     

基于HMM的红外点目标序列图像扰动补偿方法

利用红外图像扰动信号短时平稳的特性,在统计的基础上提出采用隐马尔科夫模型统计信号模型来描述扰动,得到一种基于学习的扰动模型,并利用学习得到的模型参数计算后续帧中的扰动情况,进行预测补偿,以保证目标运动的连续性,克服扰动对跟踪的影响,实验取得了较好效果。     

高精度雷达天线自抗扰控制技术研究

针对阵风扰动影响高精度雷达天线指向和跟踪性能,提出基于ADRC的阵风扰动补偿设计方案。结合天线速度环数学模型结构,分析了选用ADRC的原因;针对速度环存在时滞,基于Smith输出预估器进行设计,从而使输入到输出之间变成无时滞的惯性环节;对输入指令进行过渡过程预处理、并基于扩张状态观测器和高增益控制器对控制系统分别进行状态观测和控制律设计;仿真分析和工程现场测试表明,基于ADRC可实现对阵风扰动的有效抑制。     

无人直升机着舰甲板运动预估与补偿方法

无人直升机担负着越来越重要的作战使命,而甲板运动是影响其着舰安全的重要因素,对着舰甲板运动进行精确预估与补偿是亟待解决的难题。为此,基于自适应AR模型与最优预见控制方法,提出了一种甲板运动预估与补偿方法。基于AR模型设计甲板运动预估器时,引入时变因子设计了自适应模型参数更新律优化模型性能,强调数据的实时性,仿真结果表明,该方法在一定程度上提高了甲板运动预估的准确性,且计算相对简单;将甲板运动预估器产生的预估信号作为可预见的未来信息引入预见控制器,并基于最优控制理论对着舰甲板运动进行补偿,较好地改善了甲板运动补偿系统相位延迟问题,并在一定程度上提高了甲板运动跟踪精度,进而提高无人直升机着舰成功率。     

开关电源驱动信号斜率补偿技术的研究

对电流型PWM控制器的扰动来源进行分析，给出了解决办法和几种比较实用的斜率补偿电路，如控制电压补偿方式和电流补偿方式，对改善开关电源驱动信号稳定性有很好的效果。最后给出了一种电流环补偿电路实例予以验证。     

飞机自动着陆的一种非线性鲁棒控制器设计

将一种直接基于非线性模型的带神经网络补偿信号的逆系统方法用于具有强非线性和受不确定扰动干扰的飞机自动着陆控制,并对神经网络补偿的方式进行了改进。采用神经网络补偿动态逆反馈线性化后伪系统的逆误差,使得非线性系统在参数受到摄动或外部扰动的情况下仍能保持良好的控制效果。可以证明该方法在理论上是收敛的,对于任意的状态初值和给定的期望输出信号,能控制到指定的精度。神经网络的权值是局部收敛的,同时大量仿真表明,经过较少的神经网络离线训练,即能够获得很好的控制效果。最后通过飞机着陆下滑段的仿真验证表明,该方法具有强的鲁棒性和良好的跟踪精度。     

多延迟多瓶颈网络拥塞鲁棒控制研究

研究了具有多延迟用户源端和多瓶颈链路端的复杂网络的主动队列管理控制器的设计和稳定性分析.建立了具有非线性、输入带有时滞和不确定参数扰动的通用网络TCP/AQM动态模型.在平衡点线性化后,采用还原算法进行延迟补偿和预估,将该模型转化为无时滞的线性模型.在系统状态矩阵和输入矩阵参数扰动不满足匹配但有界的条件下,采用积分滑模变结构控制算法,基于Lyapunov稳定性理论和线性矩阵不等式方法给出了滑模可到达和渐进稳定的可行条件,根据该条件设计鲁棒主动队列管理算法.理论证明了该算法的稳定性.     

宽带DOA估计的频域时延补偿算法

针对宽带波达方向（Direction of Arrival,DOA）估计中导向矢量的频率不一致问题,提出一种新算法.首先对搜索方向信号进行时延补偿,使其与法线方向信号具有相同的阵列时延特征,同时将其它方向信号当作噪声处理,然后计算子空间的正交性并将其作为该搜索方向上空间谱值,最后给出快速算法以降低运算量.由于滤波器的群时延值不能任意改变,采用频域方法实现时延补偿.新算法不需要预估信号源数目和DOA初值,且仿真结果表明：在信号源互不相关和功率谱密度分布平坦的前提下,新算法分辨率更高、估计误差更小.     

Fixed and Adaptive Predictors for Hybrid Predictive/Transform Coding

Hybrid predictive/transform coding is studied. The usual formulation is to first apply a unitary transform and then code the transform coefficients with independent DPCM coders, i.e., the prediction is performed in the transform domain. This structure is compared to spatial domain prediction, where a difference signal is formed in the spatial domain and then coded by a transform coder. A linear spatial domain predictor which minimizes the mean square prediction error also minimizes the mean square of each transform coefficient. The two structures are equivalent if the transform domain prediction scheme is extended to a more general predictor. Hence, the structure that gives the easiest implementation can be chosen. The spatial domain structure is preferred for motion compensation and for line interlaced video signals. Interframe hybrid coding experiments are performed on interlaced videophone scenes using an adaptive transform coder. Motion compensation gives a rate reduction of 25-35 percent compared to frame difference prediction with the same mean square error. The subjective advantage is even greater, since the "dirty window" effect is not present with motion compensation. It is important to perform the motion estimation with fractional pel accuracy. Field coding with a switched predictor using previous field in moving areas is an interesting alternative to frame coding with frame difference prediction.     

High-bandwidth current control for torque-ripple compensation in PMsynchronous machines

Active compensation of torque harmonics in high-performance synchronous permanent magnet (PM) motor drives requires high-bandwidth current control. It is demonstrated that proportional integral (PI) current control exhibits performance limits, even when feedforward compensation of the rotor induced voltage and the stator inductance drop is used. High bandwidth requirements are satisfied using a digital deadbeat current controller. Sampling time delays are eliminated to the extent possible by means of a current predictor. The current controller and the predictor refer to a model of the parasitic effects of the PM synchronous machine that is acquired and adapted to parameter changes in real time. Stator current distortions due to deviations from the sinusoidal flux linkage distribution are thus eliminated. The control system facilitates compensation of high-frequency torque ripple of the machine     

Transmission distance of in-line amplifier systems withgroup-velocity-dispersion compensation

Group-velocity dispersion (GVD) compensation in in-line amplifier systems is evaluated from the viewpoint of improving the transmission distance. The nonlinear Schrodinger equation, which simulates signal propagation in optical fibers, is numerically evaluated to clarify the optimum configuration for GVD compensation. It is shown that the optimum amount of GVD compensation is about 100% of the GVD experienced by the transmitted signal. The optimum compensation interval is found to be a function of the bit rate, signal power, and dispersion parameter. For dispersion parameter values ranging from about -0.1 ps/nm/km to -10 ps/nm/km, and an amplifier noise figure of about 6 dB, the optimum compensation configuration can eliminate the GVD from in-line amplifier systems, thus improving transmission distances to those limited by self-phase modulation and higher-order GVD     

一种DC/DC斜坡补偿电路的设计

本文提出了一种峰值电流模式控制的DC/DC转换器中斜率补偿电路.电路采用上斜坡补偿（补偿信号与采样信号叠加）方式.电路由采样电路、斜坡信号产生电路、叠加电路共同组成.采样电路采样电感电流信号,并生成一个带有采样信号信息的电流信号,输入到叠加电路,与斜坡信号产生电路生成的一个斜坡电流信号进行叠加,然后共同作于一个电阻之上,输出一个带有采样信号信息与斜坡补偿信息的电压信号,实现斜坡补偿.该信号与误差放大器的输出信号共同输入到PWM（脉冲宽度调制）比较器,两信号经比较后输出驱动信号,控制功率管的关断.     

Suppression control method for torque vibration of three-phase HB-type stepping motor utilizing feedforward control

This paper proposes a method to reduce the vibration of the three-phase HB-type stepping motor with cogging torque by the feedforward compensation control. The compensation signal to suppress the vibration of the motor frame is obtained by the repetitive controller installing an online Fourier transformer and utilizing an acceleration sensor attached to the motor frame or an acoustic sensor such as a microphone placed close to the frame. The sensor is used only for the acquisition of the feedforward compensation data. The feedforward compensation signal at an arbitrary operating point is derived from the amplitude and phase data of the frequency components and the operating point data. Compensation data obtained by the repetitive controller is applied to the operating point changed by reference frequency and load condition in steady state. The compensation signal for the new operating point will be generated from compensation data utilizing polynomial equation approximation and linear interpolation method. The effectiveness of this proposed method is confirmed by the experimental results.     

Phase Compensation Receivers for Optical Communication

Phase compensation receivers are investigated in the context of optical communication, with particular emphasis on low visibility channels. It is shown that phase compensation can be viewed as a reduction of the number of spatial modes in the signal field so that an improvement in communication performance can be realized by a receiver which exploits the spatial coherence of the compressed signal mode. The phase compensation receiver structure separates nicely into configurations for measuring the phase of the signal field across the aperture and the required processors to obtain the phase compensation control from the measurements. The optimum phase control, which is chosen to spatially concentrate the signal power in the focal plane, is shown to be the minimum-mean-squared-error estimate of the aperture field phase, when the estimation error is "small enough." The phase observation-estimator structures are placed in an idealized phase compensated receiver. Minimum signal power requirements for adequate phase estimation performance are established. Communication performance, in terms of the parameters that describe the low visibility channel, is examined for both compenstated and uncompensated receivers. Depending on the system used, and for phase coherence times in the tens of milliseconds, phase compensation is most appealing for signaling rates from the middle kilobit to low megabit per second range; the resulting improvement in communication performance made possible by phase compensation is as much as 40-60 dB in optical power relative to an uncompensated receiver.     

基于波形评价准则的相位补偿方法

针对间断的单、双频信号如何进行有效相位补偿的问题展开研究。通过严格的理论推导给出了信号相位精确补偿的所需条件,即间断的单频信号可无条件进行精确补偿,间断的双频信号可在两个频率差与采样时间间隔之积为整数的条件下进行精确补偿。针对无法精确补偿的情形,提出了基于波形评价准则的近似补偿方法,并通过仿真实验比较了四种不同波形评价准则的近似补偿效果。实验结果不仅证明了本文理论和方法的有效性,同时还表明,基于波形指数熵、能量对比度准则的近似补偿效果更优,补偿后信号的频谱图峰值更高。     

开关电源峰值电流模式次谐波振荡研究

对峰值电流模式开关电源的次谐波振荡进行了系统研究,包括其产生原因、导致后果、解决方法及具体电路实现。定性分析了次谐波振荡产生的原因,从2个角度分别定量地对其进行深入研究,分析了上斜坡补偿和下斜坡补偿2种避免次谐波振荡的方法,并基于3种最基本的开关电源拓扑（Buck,Flyback和Boost）给出了具体的斜坡补偿电路,采用Hspice仿真得到不同斜率的斜坡补偿信号和自调节斜坡补偿信号。     

Ensuring predictor tracking in ADPCM speech coders under noisytransmission conditions

The problem of predictor mistracking for narrowband signals in backward adaptive ADPCM (adaptive digital pulse code modulation) speech coders is shown to arise as a result of feedback from the signal reconstruction filter to the predictor adaptation process. A class of residual-signal-driven lattice predictors (PR) is defined that guarantees tracking for all signals without regard to the order of prediction. The LR predictor enhances speech and DTMF (dual-tone multifrequency) signal transmission performance in the presence of transmission errors. Under error-free transmission conditions, a segmental SNR (signal-to-noise ratio) drop for speech of nearly 2 dB may be encountered for the LR predictor relative to the classical signal-drive lattice predictor. In most practical telecommunication applications, however, this degradation is outweighed by the improved robustness of the predictor     

Motion Compensated Composite Color Coding

This paper is concerned with motion compensation techniques for predictive coding of the composite (frequency multiplexed) color television signal. Motion estimation algorithms developed in this paper are recursive and are extensions of our previous algorithms developed for baseband luminance signals. We show, by computer simulations, that displacement of objects from frame to frame can be estimated in the composite signal domain without decomposing the composite signal into its original components. However, due to the poorer quality of displacement estimation and the resulting prediction, motion compensation in the composite signal domain is not as efficient as motion compensation in the component domain. Simulations indicate that a motion compensated predictive coder requires, in some cases, up to 25 percent fewer bits than a coder that uses previous field prediction.