一类碰撞振动系统混沌运动的QPSO-RBFNN控制

针对难以建立精确数学模型时的碰撞振动系统混沌运动控制问题，提出一种采用QPSO算法优化RBFNN的参数反馈混沌控制方法。利用分岔图、Lyapunov指数谱图、Poincaré截面图和相图分析了混沌运动与系统特定参数条件间的关联关系及表现特征，基于RBFNN设计了参数反馈混沌控制器，并将最大Lyapunov指数作为加权项构建适应度函数，以引导QPSO算法优化控制器的参数并量化评价混沌控制效果。仿真研究中，进一步分析了QPSO算法的控制参数(即收缩扩张系数)对混沌控制效果的影响。     

基于全闭环控制技术的滚珠丝杆伺服系统研究

针对滚珠丝杆全闭环伺服系统中的非线性因素影响动态精度的问题,设计了一种混合控制策略。首先,针对系统中的摩擦因素,采用了基于LuGre模型的前馈摩擦补偿;然后,为提高摩擦参数辨识精度,提出了一种改进的混沌粒子群算法,该算法将粒子群的收敛过程分成3个阶段,分别采用大惯性权重、变惯性权重与混沌寻优、小惯性权重的搜索方式,逐步提升收敛精度,避免陷入局部最优解;最后,针对系统中的间隙因素,设计了基于反向运动监测的速度补偿策略,提升了有间隙系统反向运动的动态特性。研究结果表明:相比于常规粒子群算法,改进的混沌粒子群算法使参数辨识的绝对误差平均下降42.6%;基于给定实验平台下的实验结果表明:采用LuGre摩擦补偿和反向速度补偿的混合控制策略可以缩短速度跟随误差50%以上,减少了系统反向运动时的位置误差,提升了整体位置跟踪精度,满足了数控系统的动态特性要求。     

基于CAPSO算法的修正炮弹分数阶控制器设计

为了提高修正炮弹系统模型的控制品质,采用分数阶控制器以取得更优的控制效果。针对分数阶控制器参数整定时大都需要公式推导、计算量大等问题,提出一种基于混沌自适应粒子群优化算法(CAPSO)并用于修正炮弹分数阶控制器的设计。将混沌算法与惯性权重调整的粒子群算法融合,对粒子群进行混沌初始化并对陷入局部最优的粒子进行混沌搜索,同时引入惯性权重非线性调整策略提高了算法的收敛精度,得到全局最优解。利用CAPSO算法对分数阶PIλDμ控制器的参数进行整定,并用于修正炮弹俯仰角稳定回路的控制中。通过仿真实验,验证了该优化算法的可行性。仿真结果表明,CAPSO算法在修正炮弹分数阶控制器的参数整定方面优于主导极点法、粒子群优化算法(PSO)等算法,与PSO算法相比调节时间减少了1.139 s、超调量减小了11.84%,具有收敛速度快、超调量小、稳定性好、抗干扰性强等特点;经CAPSO算法优化的分数阶PIλDμ控制器动态响应特性要优于整数阶PID控制器。     

一种航空发动机性能衰退预测的优化算法

针对航空发动机性能衰退预测问题,采用基于过程神经网络的优化算法来对发动机的燃气温度裕度(EGTM)进行预测。为克服过程神经网络学习速度慢的缺点,提出一种基于Tent映射的混沌粒子群优化算法对网络进行训练,建立预测模型。采用某航空公司的EGTM监测数据进行验证,分析结果表明,基于Tent映射的混沌粒子群优化算法具有较高的收敛速度和预测精度,可为航空发动机视情维修决策提供支持。     

改进混沌粒子群优化的灰色系统模型在机床热误差建模中的应用

为减少热误差对数控机床加工精度的影响,提高灰色系统模型(Grey system Model,GM)的预测精度,尝试将改进混沌粒子群优化(Improvemen Chaotic Particle Swarm Optimization,ICPSO)算法引入到灰色系统模型中,提出一种基于改进混沌粒子群优化算法的灰色系统模型数控机床热误差建模方法。首先,建立粒子群优化(Particle Swarm Optimization,PSO)粒子与GM(1,N)系数的映射关系;其次,ICPSO中混沌理论的Logistic映射对粒子群的位置和速度进行初始化,通过优化搜索得到最优GM(1,N)系数和输入子集;最后,建立改进混沌粒子群优化的灰色系统模型(ICPSO-GM),对数控机床热误差进行预测。仿真实验表明,ICPSO-GM预测精度高于GM和人工神经网络(ANN)模型,证明了ICPSO-GM能有效地解决数控机床热误差预测问题。     

基于混沌蜂群算法的小型无人直升机系统辨识

针对小型无人直升机在悬停状态下飞行动力学模型的系统辨识问题,提出了一种基于混沌蜂群算法(chaotic artificial bee colony algorithm,简称CABC)的辨识方法。由于直升机的数学模型是非线性的,因此用小扰动理论对其线性化,得到纵横方向待辨识的解耦模型;进一步将系统辨识问题转变成优化问题,以蜂群为搜索单位,通过群体之间的信息交流与优胜劣汰机制,使得蜂群向更优方向进化;利用混沌算子来改进侦察蜂的搜索机制,使得人工蜂群算法脱离局部最优束缚,获得更强的全局寻优能力。根据无人机实际飞行试验数据,对辨识获得的模型进行了分析与验证,结果表明,采用该辨识方法,估计出了解耦模型中的未知参数,与遗传算法和传统人工蜂群算法相比,所提算法的辨识精度更高。     

基于多项式混沌方法的柔性多体系统不确定性分析

研究了柔性多体系统的参数不确定性问题。采用绝对节点坐标方法来描述柔性体的变形,运用多项式混沌方法对柔性多体系统进行不确定性分析。通过理论分析与算例研究,对比了多项式混沌方法与广泛使用的Monte Carlo方法的精度和效率。结果表明,在相同精度要求下,多项式混沌方法在复杂柔性多体系统不确定性分析中效率更高,在工程分析中更具实用价值。     

基于混沌动态S盒的K-Hash函数构造与分析

结合传统的Hash函数结构与混沌动态S盒,提出了一种基于混沌动态S盒的带密钥的Hash函数,该方法利用混沌动态S盒和函数查找表来生成具有混沌特性的Hash散列值,与现有的混沌Hash函数相比,该方法利用混沌动态S盒来提高系统的实时性能.结果表明该算法不仅具有很好的单向性,初值和密钥敏感性,而且实行的速度快,易于实现     

非线性蛇簧联轴器混沌控制的状态观测器方法

根据状态观测器理论,给出状态观测器控制对应算法.利用此方法对非线性蛇箦联轴器混沌系统进行了仿真研究,仿真结果表明,基于状态观测器的混沌反馈控制方法具有很强的稳定控制能力,该方法适合于被控系统的混沌状态不可能全部直接测量,或状态反馈不可能物理实现的情况下,用重构状态代替真实状态组成状态反馈,将系统调整到正常的工作状态.具有重要的实际工程应用价值.     

Geffe流密码分析与实现

以非线性组合函数和线性反馈移位寄存器为基础,利用可编程逻辑门阵列进行Geffe流密码设计,并在实验中实现。该密码既能满足密码学领域对密钥序列的高质量要求,又能满足保密通信领域高速度要求。     

径向锻造工艺参数对锻透性的影响

将轴类锻件径向锻造过程的锤迹投影到单位圆柱面上,分析了径向压下率、轴向送进率等工艺参数应满足的约束条件,推导了判断径向锻造锻透性的经验三角形法则与锻造工艺参数的关系,分析了锻造工艺参数对锻透率的影响;为了验证经验法则的有效性,对轴类锻件径向锻造过程进行了数值模拟,以等效应变应大于临界值以及不出现轴向拉应力作为锻透性的判断准则,分析了工艺参数对锻透率的影响。经验准则计算结果与数值模拟结果的比较表明:采用经验准则能够有效地判断轴类锻件径向锻造过程中的锻透性,其结果偏于安全。     

面向软数控系统的混合任务调度算法

为减小因软数控混合任务不确定性而引起的加工误差,提出了面向软数控的模糊反馈调度算法和两级结构的调度策略.在分析软数控任务划分和任务模型的基础上,研究了软数控模糊反馈调度算法的结构,并推导出调度算法表.通过对比仿真试验表明:不采用模糊反馈调度,加工误差达11.9%;采用模糊反馈调度,加工误差最大值仅为1.04%.给出了两级调度策略的架构,并对调度算法、任务可调度性及时标间隔进行了研究.所提出的两级调度策略已应用到基于Windows CE.NET的软数控系统中,实测任务运行状态显示,实时任务具有很好的确定性.仿真试验和具体实施的结果表明,提出的两种算法能满足软数控系统的个性化实时应用.     

Digital Image Encryption Based on the RC5 Block Cipher Algorithm

Implementation of the RC5 block cipher algorithm for digital images in different modes of operation and its detailed encryption efficiency analysis are dealt with in this paper. The encryption efficiency analysis of the RC5 block cipher algorithm for digital images is investigated using several metrics including visual testing, maximum deviation, irregular deviation, information entropy, correlation coefficients, avalanche effect, histogram uniformity and key space analysis. The evaluation consists of theoretical derivations and practical experimentation. Experimental results have proved that the RC5 block cipher algorithm can be implemented efficiently for encryption of real-time digital images and demonstrated that the RC5 block cipher algorithm is highly secure from the strong cryptographic viewpoint.     

一种基于混沌映射的图像加密算法

应用离散混沌序列易于生成,对初值敏感以及具有白噪声的统计特性,设计了一种"仿Feistel网络结构"的数字图像加密/解密算法.该算法的所有密钥都由不同的混沌动力系统产生,增加了破译难度.算法中的置换和替代操作,组成了具有良好密码特性的SP网络结构,置换也受密钥控制,增加了算法的复杂性.加密操作的输出结果依赖于密钥的强非线性耦合,增强了安全性.在"仿Feistel网络结构"的每次迭代操作中,都能够对所有的明文进行加密,提高了加密效率.最后,以Matlab中的图像Pout为例进行了仿真试验,结果表明,该算法具有良好的安全性和效率.     

双液注浆控制器的设计与研究

针对双液四缸的注浆模式,设计了基于PLC的注浆控制器。提出了采用一个流量反馈信号调节双液流量及比例的PID控制算法。利用AMESim建立了液压回路和控制回路模型进行仿真,验证了该算法的稳定性及可靠性,并给出本控制器硬件和软件的实现方法。     

A New Spindle Current Regulation Algorithm for the CNC End Milling Process

The static and dynamic characteristics of the CNC end milling process were investigated to develop an ACC (adaptive control constraints) system for regulating spindle current. These characteristics were used to develop a new spindle current regulation algorithm composed of both adjustable proportional feedback control (adjustable P control) and fine control. For adjustable P control, a model of the entire plant was developed as a first-order system with time delay. Fine control was used to reduce the steady state error due to P control. The consequently developed spindle current regulation algorithm with a few appropriate parameters showed good global stability and applicability.     

Fringe-jump corrected far infrared tangential interferometer/polarimeter for a real-time density feedback control system of NSTX plasmas

The far infrared tangential interferometer/polarimeter (FIReTIP) of the National Spherical Torus Experiment (NSTX) has been set up to provide reliable electron density signals for a real-time density feedback control system. This work consists of two main parts: suppression of the fringe jumps that have been prohibiting the plasma density from use in the direct feedback to actuators and the conceptual design of a density feedback control system including the FIReTIP, control hardware, and software that takes advantage of the NSTX plasma control system (PCS). By investigating numerous shot data after July 2009 when the new electronics were installed, fringe jumps in the FIReTIP are well characterized, and consequently the suppressing algorithms are working properly as shown in comparisons with the Thomson scattering diagnostic. This approach is also applicable to signals taken at a 5 kHz sampling rate, which is a fundamental constraint imposed by the digitizers providing inputs to the PCS. The fringe jump correction algorithm, as well as safety and feedback modules, will be included as submodules either in the gas injection system category or a new category of density in the PCS.     

Chatter prevention for milling process by acoustic signal feedback

This paper presents how real-time chatter prevention can be realized by feedback of acoustic cutting signal, and the efficacy of the proposed adaptive spindle speed tuning algorithm is verified as well. The conventional approach to avoid chatter is to select a few appropriate operating points according to the stability lobes by experiments and then always use these preset cutting conditions. For most cases, the tremble measurement, obtained by accelerometers or dynamometers, is merely to monitor spindle vibration or detect the cutting force, respectively. In fact, these on-line measures can be more useful, instead of always being passive. Furthermore, most of these old-fashioned methodologies are invasive, expensive, and cumbersome at the milling stations. On the contrary, the acoustic cutting signal, which is fed into the data acquisition interface, Module DS1104 by dSPACE, so that an active feedback loop for spindle speed compensation can be easily established in this research, is non-invasive, inexpensive, and convenient to facilitate. In this research, both the acoustic chatter signal index (ACSI) and spindle-speed compensation strategy (SSCS) are proposed to quantify the acoustic signal and compensate the spindle speed, respectively. By converting the acoustic feedback signal into ACSI, an appropriate spindle speed compensation rate (SSCR) can be determined by SSCS based on real-time chatter level. Accordingly, the compensation command, referred to as added-on voltage (AOV), is applied to actively tune the spindle motor speed. By employing commercial software MATLAB/Simulink and DS1104 interface module to implement the intelligent controller, the proposed chatter prevention algorithm is practically verified by intensive experiments. By inspection on the precision and quality of the workpiece surface after milling, the efficacy of the real-time chatter prevention strategy via acoustic signal feedback is further examined and definitely assured.     

基于遗传算法的复合材料天线罩优化设计

研究复合材料天线罩结构优化,提出一种遗传算法与高精度通用有限元分析软件相结合优化方法。为了加快收敛进程,对遗传算法本身做出一定改进。通过对某型天线罩结构的优化计算,表明文中所提优化方法是可行有效的。     

基于单片机的随动控制系统设计

介绍了以51单片机为控制核心的数字式随动控制系统的硬件组成及软件设计。整个系统为一个三闭环的复杂多功能控制系统。其中两个模拟内环为电流环和速度环，数字外环（位置环）采用三只高精度的14位绝对式轴角编码器作为角位移传感器。该系统具有结构简单，接口功能强大，通用性强等特点，可广泛应用于负载较大的机电设备的伺服控制中。