基于扰动力矩观测器的大口径望远镜低速控制

为了增强大口径望远镜跟踪架伺服控制系统的抗扰动性能,提高其低速跟踪精度,提出了基于扰动力矩观测器的力矩补偿方法。该方法采用改进的加减速法控制转台的加减速时间,使得望远镜转台微震;通过测量电机的速度和电流响应曲线,辨识获得望远镜转台的转动惯量。然后,设计了望远镜转台的加速度估计器,根据编码器位置反馈数据,采用双积分和PD控制的方法,估计出当前系统的加速度。最后,基于转动惯量辨识和加速度估计,设计了扰动力矩观测器,根据电机的电流和转台的加速度,计算出外部的扰动力矩,并将扰动前馈补偿到电流控制器的输入端,以修正电流输入参考值。在2m望远镜控制系统中对扰动观测器的性能进行了实验验证,结果表明,加入扰动力矩观测器补偿后,在跟踪斜率为0.36(″)/s的位置斜坡时,跟踪误差值(RMS)由0.012 7″减小到0.007 3″;相比未加入扰动力矩观测器的补偿方法,望远镜的低速跟踪抖动明显减小,提高了伺服系统的低速跟踪精度,实现了对目标的平滑、稳定跟踪。     

航空光电稳定平台质量不平衡力矩的前馈补偿

讨论了旋翼直升机高频振动时产生的质量不平衡力矩对航空光电稳定平台性能的影响。基于传统光电稳定平台电流反馈、速度反馈、位置反馈的三闭环控制系统提出了一种基于系统模型的质量不平衡力矩前馈补偿方法。该方法通过标定平台质量偏心,利用加速度传感器获取平台加速度信号来对平台的质量不平衡力矩进行前馈补偿,实现对平台质量不平衡力矩的抑制,提高光电稳定平台的扰动抑制能力。实验结果表明:相对于传统三闭环控制系统,引入前馈补偿后系统的扰动隔离度至少提高了6.4dB;相对于利用扰动观测器对质量不平衡力矩进行补偿的传统补偿方案,引入前馈补偿的光电稳定平台系统不仅在低频段补偿效果提升约12.9dB,而且克服了扰动观测器在高频时不能补偿质量不平衡力矩带来的影响,使平台在全频段的扰动隔离度都大幅提高,视轴能更好地稳定在惯性空间内,具有较高的实用性和使用价值。     

基于扰动观测器的直线电机速度系统预测函数控制

针对直线电机伺服系统存在非线性、不确定性和各种扰动等特性,提出了一种基于扰动观测器和预测函数控制的复合控制方法。首先建立直线电机伺服系统的数学模型;然后设计扰动观测器对参数变化和外部干扰进行补偿,将干扰估计值反馈给预测函数控制器,建立带有干扰信息的预测模型,从而优化控制方法,提高伺服系统的控制效果。仿真结果表明,采用该复合控制方法设计的扰动观测器和预测函数控制器能够有效抑制扰动,满足系统对快速性和稳态精度的要求,系统具有较强的鲁棒性和抗干扰性,能够实现伺服系统的有效控制。     

光电稳定平台中高阶扰动观测器的应用

由于光电稳定平台在稳定视轴时易受到摩擦、风阻、不平衡以及载体扰动等干扰力矩的影响,本文研究了利用高阶扰动观测器抑制扰动力矩的机理和方法。该扰动观测器由控制对象的逆模型和进行了高阶设计的改进型滤波器组成。提出的方法将观测量作为电流环的输入,利用电流环超高的控制带宽抑制扰动力矩。对系统的扰动抑制能力进行了仿真,结果显示高阶扰动观测器对高阶扰动模型具有很好的抑制能力:对于阶跃扰动和斜坡扰动,三阶扰动观测器的抑制率为100%;对于抛物波扰动,三阶扰动观测器的抑制率为99.9999996%。另外,观测器对于控制对象模型的摄动具有很好的鲁棒性。提出的方法可以在提高伺服系统响应速度的同时保证系统的鲁棒性,满足光电稳定平台的应用要求。     

惯性稳定平台载体扰动抑制算法研究

为了减小载体扰动对机载光电设备的影响,需要设计保证惯性稳定平台稳定的控制算法。以某型号惯性稳定平台为研究对象,通过建立其机电系统的动态模型,分析了影响平台稳像精度的扰动因素,在此基础上设计了扰动观测器。此外,为有效抑制载体的周期性扰动作用,针对性地设计了重复控制算法。仿真结果表明,所提出的扰动观测器与重复控制相结合的复合控制算法能够有效地抑制载体扰动,提高系统稳像精度。     

基于自抗扰控制的转台伺服系统摩擦非线性补偿仿真研究

为克服非线性摩擦在转台伺服系统低速运行时对控制性能的影响,设计一种线性自抗扰控制器.该控制器采用线性扩张状态观测器及线性反馈,将摩擦作为系统总扰动进行实时估计,并加以补偿.基于Lugre摩擦模型建立转台伺服系统的数学模型,对这种线性自抗扰控制器进行仿真实验.结果表明,和传统PID控制器相比,所设计的控制器对非线性摩擦有良好的抑制作用,同时具有响应速度快、稳态误差小,抗扰能力强的特点.     

导引头稳定平台的扰动补偿及改进滑模控制

为提高导引头稳定平台抗扰性,提出了一种导引头稳定平台的扰动补偿及改进滑模控制策略。首先根据扰动特点将扰动分为摩擦力矩和"剩余扰动"两部分,基于Stribeck摩擦模型辨识摩擦参数,并进行摩擦力矩补偿;采用扩张高增益观测器对"剩余扰动"进行估计,并给出了扩张高增益观测器的收敛条件。然后设计了改进滑模控制器作为稳定回路的控制器实现伺服控制,采用Lyapunov函数证明其稳定性。最后,搭建测试系统分别进行了稳定平台性能测试和导引头性能测试,用于验证跟踪和抗扰效果。实验结果表明,跟踪1(°)/s的梯形波时,提出的控制器有效地补偿了摩擦,同时稳态精度提高了0.032 8(°)/s;给定三轴转台典型幅值和频率扰动下,采用提出的控制器时系统隔离度至少提高了0.57%。表明提出的控制器改善了系统抗扰性。     

负载力矩补偿的转速模拟系统复合控制

从转速模拟系统的干扰因素,对主要负载力矩干扰,提出了基于负载力矩补偿的复合控制:首先从结构不变性原理出发,通过干扰力矩观测器对速度控制进行前馈补偿,其次从增速装置后的力矩传感器获得的力矩信号进行微分负反馈补偿。仿真证明了本文提出的控制方法在抑制负载干扰方面取得了一定的效果。     

基于干扰观测和前馈补偿的电动加载复合控制

对于含有舵机位置扰动、模型参数摄动和传感器噪声等多余力的电动加载系统,仅采用传统的速度前馈补偿很难对系统多余力矩进行完全抑制。在传统速度前馈补偿的基础上针对系统扰动问题引入了扰动观测器,并利用改进的干扰观测器对高频噪声进行抑制。再通过微分负反馈阻尼补偿增强控制回路稳定性,利用重复PID控制器进行负反馈控制来改善系统的动态性能。仿真结果表明,该复合控制策略能够在很大程度上提高系统对多余力矩的抑制能力,并改善系统的加载精度。     

一种结合扰动观测器的惯性稳定平台稳定回路设计

介绍了大型重力测量惯性稳定平台的典型陀螺稳定回路设计,在此基础上以稳定回路闭环传递函数为被控对象设计了扰动观测器,实现了扰动观测器与陀螺稳定回路的结合。进行了没有扰动观测器和带有扰动观测器的稳定回路控制仿真对比,仿真结果表明,结合扰动观测器的稳定回路,具有更好的抗低频干扰力矩和高频陀螺测量噪声的能力。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.