非线性跟踪微分器在半捷联稳定平台中的应用

针对半捷联稳定平台中框架角速率的提取问题,首次提出了一种基于非线性跟踪微分器的测速方案,此方案可以避免常规差分测速带来的误差放大问题,并且可以利用预报补偿方法解决非线性跟踪微分器带来的相位延迟问题。数值仿真和实验结果表明,非线性跟踪微分器可以从框架角位置信号中准确地提取角速率信号,实验证明了基于非线性跟踪微分器的半捷联稳定方法与直接稳定方法对低频角扰动的隔离能力相当,并证明了非线性跟踪微分器在半捷联稳定平台中应用的可行性和有效性。     

跟踪微分器在半捷联导引头中的应用

对半捷联稳定方式导引头进行了研究,导出了半捷联导引头稳定控制原理,并进一步建立了完整的半捷联导引头稳定回路框图。介绍了跟踪微分器的工作原理,并对其进行了数值仿真,仿真结果显示了跟踪微分器良好的跟踪性能和滤波性能。在半捷联稳定中,为了减小由框架角位置微分求取框架角速度引入的较大的测速噪声,提出了采用跟踪微分器的方法。数值仿真和半实物实验结果说明了跟踪微分器能有效地从角位置信号中微分求得角速度信号,系统稳定精度提高了80%,证明了跟踪微分器在半捷联稳定中应用的可行性和有效性。     

前向散射阴影逆合成孔径雷达成像误差分析

阴影逆合成孔径雷达(SISAR)成像算法可以从前向散射雷达(FSR)目标回波中提取目标侧影轮廓像,其成像精度由目标的运动轨迹跟踪精度决定。该文基于小衍射角前向散射信号模型,解析推导了SISAR成像误差与目标运动轨迹跟踪误差的关系;分析了跟踪误差对目标侧影轮廓高度差和中线成像结果的影响,给出了对跟踪精度的定量要求。通过大量仿真验证了分析的正确性。     

跟踪雷达MTD信号处理角误差分析

跟踪雷达MTD信号处理机中，角误差处理采用了与传统相位检波器提取误差信号不同的数学计算方法，证明了该方法的有效性，指出了应用该方法应注意的问题，并特别提出积累对提高误差准确性的作用。     

基于跟踪微分器的模型参考自适应控制

为了处理二阶系统模型参数的大范围不确定性,提出了基于跟踪微分器的模型参考自适应控制,利用两个非线性跟踪微分器分别得到系统输出的微分信号和误差的微分信号,同时抑制了高频噪声放大效应。根据被控对象的数学模型,自适应调节律能自动实时调节控制律中的参数。实验结果表明,当雷达伺服系统被控对象模型的参数在较大范围内变化时,该新型控制器有效补偿了二阶系统参数的不确定性,提高了伺服系统稳态和动态跟踪精度,保证了系统的全局渐近稳定。     

回元导引头跟踪收敛性研究

位标器的跟踪性能由跟踪信号驱动形成的周期平均力决定,跟踪收敛性是位标器跟踪性能的重要体现。应用级数理论分析了位标器的跟踪收敛特性,得出了位标器的跟踪收敛性受到位标器跟踪系数k和跟踪相位误差影响的结论。并通过计算给出了位标器跟踪的收敛条件和收敛步长,即随着跟踪系数k与1 的偏差k及跟踪相位误差增大,跟踪收敛步长也会相应增大。这些结论会给位标器跟踪算法的设计提供重要的理论支撑。     

条带模式合成孔径激光雷达不依赖PGA的高分辨率成像演示

合成孔径激光雷达(SAL)能实现远距离目标的高分辨率成像.然而,由于所用激光波长很短,SAL系统中微小机械振动都可能在目标回波信号中引入巨大相位误差,所以,SAL很难实现稳定的相位史数据,高分辨率SAL图像的形成往往要应用额外的相位误差消除技术,特别是相位梯度自聚焦(PGA)技术.演示了一个运转良好的条带模式SAL实验室成像装置.采用一台1 550 nm波段的线性调波长激光器作为探测光源,该装置能够形成聚焦良好的高分辨率图像.通过细致的系统设计,基本抑制了在回波信号中产生相位误差的各种振动.该装置产生的相位史数据非常稳定,高分辨率图像的形成仅需简单遵照标准的SAL成像理论,无需额外借助PGA.采用点目标定标,测量得到该成像装置的方位和距离分辨率接近其理论估计.详细给出了2.4 m距离上多种目标的良好聚焦图像及相应的稳定相位史数据.     

基于扩张状态观测器的快速反射镜控制研究

为了提高快速反射镜的动态性能并降低跟踪误差,提出了利用扩张状态观测器引入反馈和灰色PID模型控制相结合的方法,该方法基于音圈电机驱动的快速反射模型,采用离散跟踪微分器对输入信号进行过渡和滤波以及对子系统零点配置,并以扩张状态观测器引入反馈和灰色PID控制,对系统的不确定因素进行了估计和补偿,并同不完全微分PID和基于跟踪微分器的零点配置方法进行了性能比较。采用随机正弦信号进行跟踪仿真,仿真结果表明,采用文中算法的跟踪效果明显优于其他算法,且跟踪误差更小,被控对象的动态性能更优,尤其在系统的模型参数发生变化时。该方法具有良好的工程应用价值。     

一种应用于限制零极点位置复数陷波器的迭代算法

基于最小均方误差准则(MMSE),本文推导出了一种修改限制零极点位置的一阶复数陷波器权值迭代算法,并进而提出了一种新的可应用于矩阵型高阶陷波器的自适应权值修改算法,该高阶陷波器由一阶陷波器作为陷波单元构成。该迭代算法直接修改陷波器权值的指数,因而在算法迭代过程中能够将高阶复数陷波器的极点始终限制在单位圆内,从而保证了陷波器的稳定工作。仿真结果表明,采用该算法的一阶和高阶复数陷波器工作稳定,对输入陷波器的宽带信号损伤小,且能快速跟踪和有效抑制其中的强单/多频信号。     

采用Simulink实现跟踪-微分器

提出的跟踪－－微分器可以在对象结构未知的情况下，从受到噪声污染的信号中提取跟踪信号和微分信号，采用Simulink可以很方便地完成跟踪－－微分器的编程。实践证明，新的跟踪－－微分吕可以应用在许多技术领域。     

车载"动中通"伺服系统的研究与仿真

分析了"动中通"中的关键技术天线稳定与波束跟踪,并讨论了它们的不同实现方法.给出了一种把天线稳定和波束跟踪相结合的方法,并把几种实现方式分别在Simulink中进行了仿真,仿真结果表明该方法不仅具有有效性,而且对于误差的修正时间也比较短.     

虚拟场景生成中摄像机机电跟踪的校准

在虚拟场景生成中，虚拟摄像机一般是小孔相机，但是带有机电跟踪系统的真实摄像机与在固定位置的小孔相机的运转是不同的。校准了由于摄像机的机电跟踪系统引起的误差。     

Precise friction control for the nonlinear friction system using the friction state observer and sliding mode control with recurrent fuzzy neural networks

This paper deals with a tracking control problem of a mechanical servo system with nonlinear dynamic friction which contains a directly immeasurable friction state variable and an uncertainty caused by incomplete parameter modeling and its variations. In order to provide an efficient solution to these control problems, we propose a composite control scheme, which consists of a friction state observer, a RFNN approximator and an approximation error compensator with sliding mode control. In first, a sliding mode controller and friction state observer are designed to estimate the unknown internal state of the LuGre friction model. Next, a RFNN is developed to approximate an unknown lumped friction uncertainty. Finally, an adaptive error compensator is designed to compensate an approximation error of RFNN. Some simulations and experiments on the mechanical servo system composed of ball-screw and DC servo motor are executed. Their results give a satisfactory performance of the proposed control scheme.     

甚高灵敏度长波红外相机测试技术

对于温度灵敏度优于10 mK的长波红外相机,如何精确测量表征其灵敏度的指标-噪声等效温差（Noise Equivalent Temperature Difference,NETD）,是一项重要的工作。首先,依照尽量缩短标准辐射传递链路减少误差项的原则,对比不同的测量方法,选取黑体直接测量法;其次,基于相机噪声理论模型,对不同温度点下的实测噪声分析,提出噪声修正方法对噪声进行修正,以此减小环境影响带来的测量误差;最后,基于NETD测量计算公式及不确定度分析理论对测试结果的不确定度进行分析评定。结果表明:针对甚高灵敏度长波红外相机所采用的测试设备及方法,可满足测试要求,测试结果相对不确定度在7.7%左右。     

Adaptive Reibungskompensation zur Verbesserung des Folgeverhaltens bei Visual Servoing

The vollowing article surveys the application of adaptive friction compensation to improve tracking behaviour using classical methods of motion control for visual servoing. Visual servoing is the use of motion control in order to follow a moving object, e.g. by the use of a robot and a gripping device. The position of the object is captured through image processing. The survey has been carried out on an XY-linear axis system using simulations and real time measurements. It shows that the tracking behaviour with classical motion control using visual servoing can be considerably improved by adaptive friction compensation. Problems which occur using such methods of motion control with visual servoing are also displayed.     

光电跟踪自抗扰控制技术研究

为了实现对快速运动目标高精度跟踪,对光电跟踪系统中的自抗扰控制技术进行了研究。根据速度闭环传递函数,利用三阶非线性扩张观测器估计系统状态变量,实现对不确定性因素的补偿,通过改变位置环被控对象传递函数提高系统的跟踪精度。对系统进行仿真与实验研究,分析自抗扰控制对光电跟踪系统动态和稳态性能的影响,与PI控制相对比,结果表明:对于高速运动目标,利用自抗扰控制技术可以将系统的跟踪精度提高7倍左右;对于低速运动目标,由于摩擦和系统噪声的影响,系统的跟踪精度仅提高了4倍左右。若在控制回路中引入相位超前环节,可以将系统的超调量降低40%,进一步改善了系统的动态性能,该技术的实现对于高精度跟踪控制的研究具有重要的应用价值。     

工业相机自热引起像点漂移模型与补偿方法

In order to reduce the influence of temperature on the image point coordinates of industrial cameras in visual measurement, the image point drift caused by the self-heating of the camera was studied, and a compensation method for the thermal image point drift of industrial cameras was proposed. The finite element simulation analysis of the industrial camera model through Ansys Workbench shows that the self-heating of the industrial camera will cause the imaging optical path change and sensor expansion change, quantitatively the influence of the optical path change and sensor expansion on the image point coordinates was analyzed, and the image point drift compensation model was established. A large number of experiments have shown that the image point drift error compensated by the model is reduced from 0.4-0.6 pixel to 0.1-0.2 pixel, which is equivalent to the image point drift suppression effect achieved by hardware thermal control. However, compared with the thermal control device, the method of using the model for compensation has obvious advantages of simple structure and low cost. The temperature compensation model proposed in this research provides a theoretical basis for reducing the image point drift error caused by the self-heating of the camera in the visual measurement.     

A Repetitive Model Predictive Control Approach for Precision Tracking of a Linear Motion System

In this paper, a new model predictive control (MPC) approach suitable for high precision linear motion drive operating with repetitive tracking tasks is presented. For the proposed predictive controller, the feedforward controller of the conventional MPC has been modified to provide zero-phase learning property. This is achieved by augmenting the reference trajectory with a phase-compensated term that is updated with the historical tracking error. The proposed approach attempts to combine the merits of both the conventional MPC and repetitive control schemes. Experimental results have demonstrated that the system effectively reduces the tracking error from the periodic disturbance caused by the friction. Its performance under varying reference conditions and different loadings shows that the system is robust.      

Robust Control of PM Spherical Stepper Motor Based on Neural Networks

There are many uncertainties and disturbances in the real dynamic system of a spherical stepper motor that make traditional control methods with lower precision, such as uncertain changes of magnetic field, load, and friction that generate speed ripple and deteriorate the 3-D tracking performance of the spherical motor system. In this paper, an available method is proposed to solve them by using neural networks (NNs) and a robust control scheme for improving the performance. First, a simplified torque calculation model based on finite-element method results can guarantee quick prediction of electromagnetic torque with lower error. Thus, the system model considering the friction, load, and disturbances is developed. Second, a robust NN (RNN) control scheme is presented to eliminate uncertainties to improve the tracking robust stability and overcome the undesired influence of uncertainties based on the nonlinear system dynamic model under continuous-trajectory tracking mode. Finally, as an example, the step-response and continuous-tracking processes of the motor using an RNN controller are simulated, and experiments, including the tracking using RNN proportional–differential control, are carried out to confirm the usefulness of the proposed control scheme. The simulation and experimental results of the proposed control scheme on the spherical stepper motor system demonstrate the effectiveness on satisfactory tracking performance.      

基于改进LK光流法的MEMS面内运动分析技术

为获取微机电系统(MEMS)面内运动过程中的动态 特征,文中提出了一个MEMS面内运 动测量系统．该系统通过FPGA产生相机外触发和频闪光源两路时钟同步驱动脉冲,利用频闪 成像的原理对谐振状态下的MEMS器件进行图像采样．对图像序列进行Canny边缘检测后,引 入Shi-Tomasi角点和Lucas-Kanade光流追踪的方法进行运动分析,获取器件的幅相信息参 数 ．使用该系统对一个定制的微陀螺仪进行实验测量,实验证明该技术可实现MEMS面内运动的 亚像素精度测量,与传统的LK光流法匹配相比,能够减少由图像灰度值变化带来的测量误差 ,同时该方法具有较好的测量精度,测量重复性可达10 nm。