基于Ansys的往复式压缩机出口管道振动分析与改造

对往复式压缩机出口管道存在的振动故障进行了分析,基于振动特性方程,利用Ansys参数化编程建立了复原现场的有限元数值模型,在此基础上进行了有限元模态分析和谐响应分析,得到了管系的前20阶固有频率和各激振倍频下的振动位移值。同时提出了修改系统刚度的振动控制方案,经计算验证发现,改造后管道固有频率有所提高,能有效避开原共振频率,并对改造后可能出现的共振倍频进行了谐响应分析,发现改造后管道系统振动能量趋于均匀,管系振幅明显降低。     

混沌系统的渐近跟踪控制器设计

目的设计Lorenz混沌系统渐近跟踪控制器,消除系统混沌现象,提高控制效果．方法基于微分几何方法中的同胚变换和状态反馈,对系统进行局部线性化处理,提出反馈控制律．在此基础上,设置跟踪目标,定义输出跟踪误差向量,设计系统渐进跟踪控制器．结果在所设计的反馈控制律作用下,系统输出实现了对给定信号的渐进跟踪,通过调整反馈强度,可改善跟踪速度．结论仿真结果表明,采用微分几何方法,可以使混沌系统输出渐近跟踪目标,即系统输出由初始混沌轨道转入非混沌轨道,最终进入目标轨道,且输出具有较好的暂态特性,同时可以灵活地调整反馈强度．     

基于状态观测器噪声干扰的混沌控制与同步

提出了一种基于状态观测器参数控制噪声干扰下的混沌数字通信控制方法。利用一混沌系统驱动另一混沌系统产生出理想的输出波形,将该控制方法用于混沌控制;根据噪声干扰下的系统方程构造出状态观测器,并将该状态观测器用于具有测量噪声、输入噪声干扰的混沌系统和Lorenz混沌系统的控制;改变观测器的作用范围,可以将混沌系统稳定到固有的区域内。仿真结果证实了该控制方法的有效性。     

基于观测器的永磁同步电机模糊自适应混沌控制

针对混沌现象能够影响永磁同步电动机驱动系统稳定性的问题,本文根据模糊自适应控制和反步设计法的原理,研究了具有不确定参数的永磁同步电动机混沌系统位置跟踪控制,设计了一种新型的降维观测器来估计系统的转子角速度,并利用模糊逻辑系统对永磁同步电动机混沌系统中的非线性函数进行逼近,同时采用反步设计方法,构造了模糊自适应控制器,并在Matlab环境下进行仿真。仿真结果表明,该控制方法能够避免永磁同步电动机出现混沌现象,确保系统可以快速跟踪期望的信号,并对永磁同步电动机混沌系统进行有效控制,该控制策略能够克服永磁同步电动机参数不确定性的影响,实现了对永磁同步电动机的位置跟踪控制。该研究具有实际应用价值。     

混沌化控制综述

在介绍混沌化控制的原理、方法、应用的基础上,对如下混沌化控制方法的国内外现状进行综述:基于李雅普诺夫指数配置的混沌化控制、对受控系统施加线性或非线性状态反馈输入的混沌化控制、通过对已有混沌吸引子进行变异来实现混沌化控制、通过施加时滞参数摄动或时滞状态反馈来实现混沌化控制、通过受控系统状态对已知混沌参考系统状态的精确跟踪来实现混沌化控制.最后对混沌化控制的发展趋势进行展望.     

参数不确定混沌系统的动态面输出调节方法

针对一类严参数反馈形式混沌系统,研究含有未知参数向量的线性中性稳定外系统驱动下的输出调节问题.根据非线性系统输出调节问题可解的必要条件,将严参数反馈混沌系统的输出调节问题转化为镇定问题.在前n-1步递推中,通过采用动态面控制设计虚拟控制律,简化了控制律设计的复杂性;第n步应用内模原理,结合自适应技术,设计输出调节控制器.应用Lyapunov稳定性理论,证明跟踪误差全局一致终结有界.仿真结果验证了控制方案的有效性.     

一类混合混沌系统的无源控制

针对一类复杂的混合混沌动力学系统,研究系统的无源控制问题.根据无源性网络理论,分析了将混合混沌系统等效为无源系统的基本条件;在此基础上,设计混沌动力学系统的状态反馈控制器,实现最小相位混沌系统和弱最小相位混沌系统在任意平衡点上的渐近稳定.研究表明,利用等效无源控制策略对系统中的混沌行为实行切换控制,可以消除系统中的混沌运动,降低系统自激振动的危害,实现系统的快速稳定.     

不确定连续非线性系统鲁棒混沌反控制

为了实现一类非线性系统的鲁棒混沌反控制,提出非线性不确定系统鲁棒混沌反控制的非线性比例积分微分控制 （NPID）方法.该方法借助微分跟随器和数值微分环节分别提取驱动混沌动态系统和受控系统输出的微分信号，并在此基 础上根据时间加权的误差绝对值积分（ITAE）最小的原则设计非线性比例积分微分控制器，使受控系统的输出能良好地 跟踪驱动混沌系统输出，实现非线性不确定系统的鲁棒混沌反控制.将混沌反控制的适用范围由离散时间系统拓展到连续 时间系统，由参数结构已知的线性稳定系统拓展到参数结构未知的非线性稳定和不稳定系统.分析和仿真结果表明，微分 跟随器和数值微分环节可以对驱动混沌动态系统和受控系统的微分信号进行高精度实时提取，控制策略具有鲁棒性，控 制器的设计具有不受李雅普诺夫指数配置求取困难和微分几何控制器设计计算复杂性的约束.     

基于符号动力学控制混沌动力学系统

提出一种新的混沌动力学系统的控制方法．首先用符号动力学对混沌吸引子进行粗粒化划分,然后利用混沌系统对噪声的敏感性和短期可预测性,用小控制量对混沌系统进行控制,使之沿任意允许的符号序列所代表的轨道演化,将被控系统的状态维持在一定的范围之内。     

一种新的离散混沌系统的延时反馈控制

以跟踪误差渐进趋近于零为基础,提出了一种新的离散混沌系统延时反馈控制方法。该方法利用离散混沌系统的N步延时输出来估计系统的不稳定N周期轨道,并作为跟踪目标,使受控混沌系统既能稳定到相空间的确定点,又能稳定到N周期轨道。理论分析和实验均表明该控制方法具有鲁棒性。     

Fuzzy control on automatic frequency tracking of ultrasonic vibration system with high power and high quality factor Q

In order to realize automatic tracking drift of resonance frequency of ultrasonic vibration system with high power and high quality factor Q,adaptive fuzzy control was studied with a self-fabricated ultrasonic plastic welding machine.At first,relations between amplitude of vibration and frequency as well as main loop current and amplitude of vibration were analyzed.From this analysis,we deduced that frequency tracking process of the vibration system can be concluded as an optimizing problem of one dimensional fluctuant extremum of main loop current in vibration system.Then a method of self-optimizing fuzzy control,used for the realization of automatic frequency tracking in vibration system,is presented on the basis of self-optimizing adaptive control approach and fuzzy control approach.The result of experiments shows that the fuzzy self-optimizing method can solve the problem of tracking frequency drift very well.Response time of tracking in the system is less than 50 ms,which basically meets the requirements of frequency tracking in ultrasonic plastic welding machine.     

自适应控制的自动打桩振动锤

振动锤利用共振理论设计，自适应控制系统在线测试地基土的参数，实时控制振动锤振动频率，使其工作在最优状态。计算机仿真表明这种控制方案可行。     

早期故障信号基于调制随机共振的核主元检测

针对淹没在强噪声中具有高频多周期成分的早期故障信号,提出了并联调制随机共振与核主元分析系统.将信号的特征频率通过调制共振系统进行增强,并将功率谱组成多元统计向量,通过非线性映射,在高维空间进行特征提取,利用T2统计量和F分布的控制限进行检测.利用仿真的轴承转子振动信号与滚动轴承冲击信号进行了验证,实验表明系统能够及时地对早期故障进行预警.     

Resonance Suppression Strategy for Humanoid Robot Arm

To address the problem of resonance in the control of a robot arm, a resonance suppression strategy is proposed for a single-joint humanoid robot arm based on the proportional-resonant(PR) controller. First, an arm joint model of the humanoid robot is established. Then the influence of resonance frequency on the performance of the control system with the robot arm is analyzed. The voltage fluctuation of the drive motor caused by the changes in arm motion is recognized as the disturbance of the current loop. The PR controller has the characteristic of disturbance rejection at a specific frequency. The output fluctuation of the driving system caused by the change of arm motion state at the resonance frequency is suppressed. Therefore the output current of the inverter will not be affected by the vibration of the arm at the resonance frequency. Finally, the control system is verified by MATLAB/Simulink simulation. The simulation results demonstrate that the control strategy for the humanoid robot arm based on the PR controller can suppress the resonance of the arm effectively, improving the dynamic performance and system stability.     

Theoretical and experimental study on non-linear vibration characteristic of gear transmission system

In order to investigate the vibration of gear transmission system with clearance, a vibratory test-bed of the gear transmission system was designed. The non-linear dynamic model of the system was presented, with consideration of the effects of nonlinear dynamic gear mesh excitation, flexible rotors and bearings. Integration method was used to investigate the non-linear dynamic response of the system. The results imply that when the mesh frequency is near the natural frequency of gear pair, it is the first primary resonance, the bifurcation appears, and the vibration becomes to be chaotic motion rapidly. When the speed is close to the natural frequency of the first-order bending vibration, it is the second primary resonance, the periodic motion changes to chaos by period doubling bifurcation. The vibratory measurement of test-bed of the gear transmission system was performed. Accelerometers were employed to measure the high frequency vibration. Experimental results show that the vibration acceleration of the gear transmission system includes mesh frequency and sideband. The numerical calculation results of low speed can be validated by experimental results basically. It means that the presented non-linear dynamic model of the gear transmission system is right.     

超声振动钻孔半波长振动系统的设计

为了避免碳纤维复合材料传统钻孔出入口易劈裂、内部易分层、掉渣、刀具易磨损,同时满足像卫星主体等碳纤维复合材料大型构件多孔位、多角度钻孔的要求,研制了一种便携式超声旋转钻,基于一维振动理论,设计了体积小（长130mm)、重量轻（1.6kg)、转动惯量小的半波长振动系统,由于在加工中依据不同的要求经常更换不同直径、不同长度、不同材质的工具将引起振动系统的谐振频率飘移,针对设计的半波长振动系统,基于阻抗匹配原则,给出了振动系统与工具之间进行阻抗匹配的方法,建立了更换工具的简易计算式;保证了更换工具后,振动系统处于最佳的工作状态。     

A new hybrid piezoelectric ultrasonic motor with two stators

A new hybrid piezoelectric ultrasonic motor, which consists of one rotor and two stators, was proposed in this paper. In order to match the resonance frequencies of longitudinal vibration and torsional vibration excited in the stators, a symmetrical structure was adopted in design of the motor. A so-called mass matching method, namely adding two rings to the outside circumference of the two stators respectively, was used to adjust the resonance frequencies of these two vibrations. A finite element model was developed using ANSYS software for the purpose of analyzing the resonance frequencies of longitudinal vibration and torsional vibration as well as the function of the adjusting rings. The results show that the resonance frequency of torsional vibration varies with the position of the ring, but the resonance frequency of longitudinal vibration changes little. By means of adjusting the mass and the position of the rings, the first order resonance frequency of longitudinal vibration is coincided with that of torsional vibration and the value is 20.75kHz. An experimental prototype motor was fabricated according to the analytical results and its performance is in agreement with the theoretical predictions. The speed of motor reaches the maximum 92r/min at the working frequency 19.0kHz.     

振动教学实验台系统研制

针对目前市场上现有的振动实验教学系统的情况,研制开发了一套振动教学实验系统。该系统基础结构刚性高,不会与振动梁发生耦合振动,有较宽的频率范围,可实现非接触激振距离微调及振动的主动控制。其组成原理反映了一般工程测试系统的要求,具有力学模型设计合理,集激振、拾振、信号处理为一体的特点,可广泛应用在机械振动学、理论力学、机械测试学等课程的教学实验以及机电产品创新设计等综合性实验中。     

大直径缸套功率超声振动珩磨装置的研制

介绍了功率超声振动珩磨装置,它是机、电、声一体化高新技术产品,是一种提高发动机缸套表面质量的新型加工设备,这种高新技术产品的组成及结构,可以广泛应用于机动车辆行业,详细地介绍了超声波发生器、换能器、变幅杆、弯曲振动圆盘、声振系统等各组成部分的工作原理及具体的设计和应用,最后,介绍它的优点,以便引起同行的重视,使这一高新技术产品尽快实现产业化并得到广泛的应用以便促进我国的民族产业的发展,适应加入WTO的需求,增加国际竞争力.