基于滑模变结构的陀螺稳定平台非线性解耦控制

为了消除陀螺稳定平台系统中各框架间的非线性耦合影响,设计了一种滑模非线性解耦控制算法.分析了高精度三轴陀螺稳定平台框架间的非线性耦合特性,建立了系统的动力学模型.利用非线性微分几何方法对系统进行了输入输出解耦控制设计,结合模型跟踪滑模变结构控制方法消除了系统解耦控制中的非线性扰动因素.针对滑模控制中的抖动问题,设计了带有边界层的积分滑模控制器,有效减弱了控制器的抖振现象,提高了系统解耦精度.在某型号电视导引头稳定平台系统中测试表明了该解耦控制方法的有效性和可行性.同PID方法和不带边界层的滑模控制方法相比较,该解耦方法的解耦效果明显优于其他两种方法.     

数控机床直线同步电动机磁悬浮系统反馈线性化控制的研究

由于在数控机床直线同步电动机磁悬浮系统中,直轴电流、悬浮高度与水平速度之间存在非线性耦合,以及负载扰动等不确定因素,会对控制系统产生诸多不利影响。针对该问题,提出了一种新型解耦控制方法。建立可控励磁磁悬浮直线同步电动机(controllable excitation linear magnetic suspension synchronous motor, CELMSSM)的数学模型;通过选取适当的状态变量得到该电动机的仿射非线性模型;在传统电流控制的基础上,利用非线性系统的微分几何理论,通过坐标变换与状态反馈,将电动机仿射非线性模型解耦线性化为直轴电流子系统、水平速度子系统以及悬浮高度子系统的3个可独立控制的线性子系统;根据最优极点配置法设计系统的控制规律,从而实现可控励磁磁悬浮直线同步电动机的动态解耦控制。最后,对控制系统进行仿真研究,结果表明通过反馈线性化控制与传统PI控制仿真对比,所提出的控制策略可使系统的动、静态性能得到显著增强。     

方位俯仰型虚拟跟踪瞄准装置的机电动力学仿真

以方位俯仰型跟踪瞄准系统为研究对象,基于机电动力学的Lagrange-Maxwell方程,给出了非线性的双轴耦合机电动力学模型;并以某高功率微波天线为例,完成了基于PID控制算法的跟踪瞄准机电动力学仿真。仿真结果证实了方位俯仰跟瞄装置的机电动力学模型的合理性,并且为目标跟瞄系统的虚拟现实研究提供了理论依据。     

机载定向红外对抗激光指示系统控制设计

为提高机载激光指示设备三轴工作系统的控制精度,对其进行了建模仿真分析.根据拉格朗日定理推导出指示设备三轴耦合框架非线性动力学模型,对各框架回转轴之间速度耦合及动力学耦合进行分析,并理论推导出其解析关系.根据执行元件力矩电机的电学和力学方程,建立了被控制对象开环传递函数矩阵,并进一步设计串联解耦控制器来实现系统解耦控制.分析表明,解耦后,在系统中串联添加校正环节,可以使系统在稳定工作的同时达到快速响应的要求.阶跃响应速度最快时间为:方位框达0.45 s,俯仰框达0.50 s,横滚框为0.85 s.最后,通过计算机仿真验证理论模型的正确性,为今后研究和设计高精度机载激光指示设备的控制器以及选取和优化控制参数提供了理论参考和模型基础.     

一种机载DIRCM激光指示系统设计

为提高机载激光指示设备三轴工作系统的控制精度,对其进行了建模仿真分析。根据拉格朗日定理推导出指示设备三轴耦合框架非线性动力学模型,对各框架回转轴之间速度耦合及动力学耦合进行分析,并理论推导出其解析关系。根据执行元件力矩电机的电学和力学方程,建立了被控制对象开环传递函数矩阵,并进一步设计串联解耦控制器来实现系统解耦控制。分析表明,解耦后,在系统中串联添加校正环节,可以使系统在稳定工作的同时达到快速响应的要求。阶跃响应速度最快时间为:方位框达0.45 s,俯仰框达0.50 s,横滚框为0.85 s。最后,通过计算机仿真验证理论模型的正确性,为今后研究和设计高精度机载激光指示设备的控制器以及选取和优化控制参数提供了理论参考和模型基础。     

整车主动悬架解耦控制

由于车辆各个车轮受路面的激励,车辆簧上质量的振动耦合了各个车轮引起的振动。为使车辆有效减振,建立了带主动悬架的整车非线性模型并利用微分几何方法对该非线性模型进行解耦。经过解耦的悬架系统簧上质量的垂向、俯仰和侧倾振动互相独立,成为独立的线性子系统,从而可以实现对其单独控制。设计了减振控制律,对解耦的悬架系统减振。仿真结果表明,簧上质量各个方向振动大幅衰减,说明该控制方法是有效的。     

平衡重式叉车底盘神经网络逆系统解耦控制

针对平衡重式叉车底盘各子系统间的干涉和耦合特性,利用非线性系统的神经网络逆系统方法进行叉车主动后轮转向(ARS)与直接横摆力矩控制(DYC)的解耦控制.在分析底盘系统可逆性的基础上,确定解耦变量配对关系,建立BP(Back Propagation)神经网络逆系统模型并串联到原底盘系统前,使叉车底盘系统解耦成两个独立的伪线性系统;设计PD(Proportion Differentiation)闭环控制器并与神经网络逆系统组成复合控制器,并进行仿真验证.仿真结果表明:神经网络逆系统解耦控制策略能够消除底盘各子系统间的干涉和耦合,提升叉车的状态跟踪和操纵稳定性.     

基于粒子群算法的三轴跟瞄装置跟踪策略研究

三轴跟瞄装置可以解决方位俯仰两轴跟瞄装置存在的盲区问题,能够实现全方位跟踪空间目标.然而三轴跟瞄装置测量值与空间位置多对一的特性决定了跟踪策略的多样性和系统引导的复杂性,传统的切换控制方法制约了三轴跟瞄装置跟瞄精度的进一步提高.通过详细分析三轴跟瞄装置运动过程,在给定当前位置角、探测器误差角的条件下,将求解三轴执行角增量的计算方法转化为求最优值问题.采用粒子群算法求得了不同初始条件下满足目标要求的角增量组合,分析比较了三轴跟瞄装置和方位俯仰两轴跟瞄装置跟瞄性能的差异,结果验证了三轴跟瞄装置运动过程分析方法以及用粒子群算法求解角增量组合的有效性.     

基于博弈论和功能分配的汽车底盘系统协调控制

考虑汽车底盘悬架、转向、制动子系统间耦合动力学关系,建立高阶非线性动力学模型。对各子系统设计局部最优控制器,对悬架子系统设计非线性H∞控制器,对转向子系统设计直接横摆力矩比例积分微分(Proportion-integration-differentiation, PID)控制器,对制动子系统设计滑模变结构控制器。为进一步提高整车全局控制性能,基于功能分配原理对子系统控制功能进行分配,采用博弈论对子系统控制功能指标进行博弈,设计上层协调控制器以输出期望的控制作用,模糊规则实时自整定子系统控制器输出量以跟踪期望控制目标。基于Matlab/Simulink软件,对整车协调控制系统进行仿真,采用ARM构建底盘功能分配的控制系统实车试验平台,进行实车道路试验。结果表明,基于博弈论的整车协调控制系统较子系统单独控制、不加控制时均能取得更好的控制性能,验证了协调控制的有效性。     

基于PSO的某稳瞄系统滑模变结构控制研究

针对某坦克瞄准镜稳定控制系统,考虑到其中二分之一传动机构间隙和上反射镜固定轴导致的黏性摩擦所引起的非线性时变特征,提出基于粒子群算法的模糊滑模变结构控制方法,旨在优化稳定控制系统滑模控制器的参数,增强系统鲁棒性,并有效弱化抖振。仿真结果表明,该设计可有效提高瞄控系统稳态精度,为坦克稳瞄系统的控制提供了一种切实可行的控制方案。     

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.     

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。     

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....     

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.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.