弹载电动舵机幂次滑模反演控制

针对高频响弹载电动舵机系统存在的齿隙非线性、参数时变、未知扰动等问题,提出一种幂次型快速Terminal滑模反演控制策略.设计连续可微函数逼近齿隙非线性环节的死区模型,建立拟合系统的状态空间模型并划分为3个子系统进行控制设计.采用反演控制思想设计快速幂次Terminal滑模控制器,内环采用直接转矩控制控制策略,提高响应速度.应用Lyapunov方法证明闭环系统跟踪误差的有限时间收敛特性,实现了对齿隙非线性的精确补偿.实验结果验证了所提出控制策略的有效性,与反演控制和PID控制策略相比,弹载电动舵机的控制精度、收敛速度及鲁棒性有显著提高.      

基于DSP的电动舵机伺服与控制

主要阐述基于DSP的电动舵机伺服系统的设计与实现,主要研究内容为舵机控制器硬件设计、软件设计和电动舵机伺服系统的性能优化.设计初期对数学模型进行了仿真实验,以事先发现设计不合理的方面,通过仿真中对数学模型的参数进行调整,可以预期数字式电动舵系统的控制律参数.因为数学模型与工程实践不可避免的存在一些差异,所以设计在工程中实现后,还通过电动舵机伺服系统联试试验对控制律参数进行再调整,以满足电动舵系统的性能要求.     

基于气动人工肌肉的混合位置跟踪控制

针对一种气动人工肌肉驱动的弹簧质量位置控制系统,设计了一个带有自适应模糊小脑模型（Cerebellar Model Articulation Controller,CMAC）在线逼近的离散趋近律滑模混合控制器.该混合控制器中离散趋近律滑模策略产生控制器的输出;自适应模糊CMAC用以逼近气动人工肌肉系统中的不确定项.CMAC网络权值的在线学习调整保证了自适应模糊CMAC的逼近性能.对离散抗饱和PID控制器（DASPID）与自适应模糊CMAC离散滑模混合控制器（HybridC）的位置跟踪控制性能进行了对比实验.实验结果表明,HybridC较之DASPID有更好的位置跟踪控制性能.当期望参考输入为正弦信号时,DASPID的最大位置跟踪误差为±15 mm;而HybridC的最大位置跟踪误差仅为±07 mm,平均位置跟踪误差大约仅为±02 mm.并且,离散滑模所固有的抖振现象得到了有效的抑制.     

离散滑模控制在发动机怠速设计中的应用

利用一种新的离散滑模控制方法, 设计了发动机怠速的离散滑模(DSM)控制器, 用已开发出的4缸、1.4L的AJR发动机怠速控制系统的非线性模型进行发动机怠速转速的控制. 实验结果表明, 与原机的控制器相比较而言, DSM控制器在跟踪期望怠速转速及抗干扰等方面具有优良的性能.     

基于输出反馈的离散滑模控制器设计

针对一类多输入多输出不确定离散系统,设计了输出反馈滑模变结构控制器.基于极点配置的方法设计了稳定的滑模面,然后分析传统离散指数趋近律设计方法的优缺点,根据滑模到达条件提出一种改进的指数趋近律.该控制律加快了系统状态的响应速度,同时降低了抖振.仿真结果证明所设计的控制器能够在系统状态不完全可测情况下具有良好的性能,验证了该设计方法的可行性和有效性.     

离散时间系统的滑模控制器设计

针对离散时间系统变结构控制器的设计问题,提出了滑模控制器设计方法.该方法不仅改善了系统到达阶段的品质,能够使系统快速趋向滑模面,且有效消除系统的抖振.理论分析和仿真结果表明,此方法是可行的,使所得到的变结构控制系统具有良好的性能,保证了系统的稳定性.     

船舶航向跟踪系统自适应滤波反步终端滑模控制

针对船舶航向非线性系统,提出了一种基于自适应滤波反步法的终端滑模控制器. 系统由二阶非线性野本模型和舵机响应模型串联组成,考虑了模型不确定性和外部干扰等未知项,并由模糊系统对未知项进行在线逼近. 首先引入二阶低通滤波器,避免了对虚拟控制律的解析求导,从而简化了反步控制器的设计,而且滤波器的低通特性可大大减小测量噪声的影响;然后利用滤波反步法的结果设计了终端滑模面,并最终得到了使系统跟踪误差有限时间收敛的终端滑模控制器. 根据Lyapunov理论证明了闭环系统所有误差变量均是一致最终有界的. 仿真结果验证了所提方法的有效性.      

基于Kalman滤波的力矩电机直驱转台系统数字滑模控制

针对含有测量噪声和过程噪声的力矩电机直驱转台伺服系统,提出一种基于卡尔曼滤波器的数字滑模控制策略。首先,考虑到现有控制多采用计算机进行离散数字控制,首先将力矩电机伺服系统的数学模型进行数字离散化;其次,对离散化系统设计基于指数趋近率的软切换滑模控制器;最后,将设计的滑模控制器信号和带噪声的输出通过Kalman滤波器,得到系统最终输出信号。仿真实验结果表明:所设计的控制器对系统的噪声具有很强的鲁棒性和跟踪性能。     

离散广义双线性系统的有限时间滑模控制

利用变结构控制方法,研究了一类离散广义双线性系统的有限时间滑模控制器设计问题。利用Lyapunov函数的方法,给出了离散广义双线性系统的滑模控制的理想准滑动模态和趋近律形式的到达条件,设计滑模控制器,实现离散广义双线性闭环系统是因果的、稳定的,同时也使得滑动模在有限时间内到达切换面或切换带内实现滑模运动,通过数值算例说明了设计方法的可行性和有效性。     

角钢塔螺栓的紧固控制技术

针对角钢塔螺栓紧固作业需求,研究了一种轻量化、扭矩可准确控制的电动扳手.为了解决轻量化问题,提出了一种自抗扰控制器与滑模观测器融合算法,实现了无扭矩传感器的电动扳手扭矩参数估计与控制.首先,将自抗扰控制器引进扭矩环、速度环,在对其总扰动量进行估计的同时得到角加速度的估计值,然后将该角加速度值作为二阶滑模观测器的输入进行紧固扭矩值的估计,解决了二阶滑模观测器中变量的导数值难以获得的问题.仿真和实验结果表明,与传统PID控制器、滑模控制器相比,所提方法可实现扭矩的准确估计,具有扭矩调节时间短,超调小的特点.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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