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Linhong WANG Bo WU Runsheng DU Shuzi YANG 《Frontiers of Mechanical Engineering in China》2008,3(4):385-391
This paper employs the SVD (singular value decomposition) method to study dynamic characteristics of a numerical control (NC)
table. Acceleration signals of the NC table at three directions are tested; the singular spectrum of the signals is acquired
with SVD; principal components of the signals are found out; dynamic characteristics of the signals and their contributing
factors are studied by extracting dynamic characteristics of principal components; and signals and principal components are
quantitatively analyzed by calculating signal energy. Results indicate that signal characteristics of the previous two principal
components are apparent, based on which dynamic characteristics of chaotic signal can be extracted. Signal at the perpendicular
direction of the table is significantly correlated with that at the horizontal motion direction, which indicates that they
are excited from the same vibration source. However, signals perpendicular to each other in terms of the motion direction
at the horizontal level are rarely correlated; the total signal energy is maximum at the motion direction, minimum at the
horizontal non-motion direction, and medium at the perpendicular non-motion direction. Bending vibration of the lead screw
at the perpendicular direction is far more violent than that at the horizontal direction. 相似文献
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驾驶风格评价是智能交通领域的重要研究课题,一般采用频域或时域的分析方法对其进行定性的分类和识别,缺乏客观定量的评价体系。提出一种基于相空间重构的驾驶风格定量分析方法。首先,采用汽车测试数据和局部性神经网络建立个性化的驾驶员模型;然后,将个性化驾驶员模型应用于标准驾驶周期测试工况的速度跟随试验,以实现驾驶行为的标准化;最后,对标准化驾驶行为进行相空间重构,提出一种基于关联维数的驾驶风格指数,用于定量评估驾驶的激进程度,并应用于驾驶员风格的识别,仿真结果验证了所提方法的有效性。 相似文献
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鉴于闸门流激振动过程的复杂性,对水弹性模型试验中闸门在不同开度下的实测加速度响应数据进行了混沌特性分析。首先,对实测数据进行相空间重构,分别采用平均互信息法和平均伪最近邻域法计算最佳时间延迟和最佳嵌入维数;然后,基于嵌入参数计算关联维数D_2和最大Lyapunov指数λ_1,并对各计算参数的分布规律进行分析。研究表明:闸门侧向振动的复杂性相对其他振动方向更高,中间开度时的振动复杂性比大开度或小开度更显著;竖直向振动与顺流向振动中呈现出了较低维(D_2=3.342~5.130)的混沌吸引子,表明较少的独立变量即可描述闸门竖直向及顺流向振动的规律;λ_1随闸门开度的变化规律呈现"两边小中间大"的趋势,表明闸门在中间开度时的振动预测准确性较低。 相似文献
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数控机床运动精度状态的变化是一个复杂非线性动力系统的时空演化过程,难以通过数学建模方法分析其演化规律。提出基于混沌相空间重构理论的数控机床运动精度演化分析方法。根据混沌系统内在的规律性和有序性,分析基于相空间重构的数控机床精度演化原理,对数控机床运动精度的一维时间序列进行相空间重构,从而得到与原系统拓扑同构的高维相空间。提出用相点轨迹描述运动精度在相空间中的演化规律,构造一个非线性演化模型,用相点的多维分量构成输入向量,对其精度趋势进行演化。实验结果表明,基于混沌相空间重构的演化模型,可以很好地追踪数控机床运动精度的演变趋势和规律,且具有较高的演化精度。 相似文献
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对高速数控转台动平衡检测理论进行了剖析,阐述了动平衡评价标准,提出了高速数控转台动平衡检测硬件的选用方案,并对高速转台动平衡的调整方法进行了详细说明.结合实例,验证了动平衡调整方案,结果表明此项研究能够降低高速数控转台在使用中由于动不平衡引起的振动,进而提高机床加工的精度及机床的使用寿命. 相似文献
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为了有助于并联机床数控系统和仿真系统的开发,克服建立数学模型实现机床数控代码虚实映射计算的缺点,文章提出了综合利用CAD软件的装配约束和尺寸驱动功能来实现虚实映射的方法。给出了并联机床机构简图和虚拟样机实体模型,通过将数控代码进行预处理,进行了并联机床的虚实映射计算,即给定刀具位置和姿态的驱动尺寸、驱动杆件长度的被驱动尺寸,在装配约束作用下驱动尺寸带动整个机构运动,记录杆件长度的被驱动尺寸,求解出杆长的值。计算机模拟结果表明,该方法简捷直观、速度快、求解精度高,可以完成其他多自由度并联机构的虚实映射计算,为并联机构的虚实映射计算提供了更有效的工具。 相似文献
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切削负荷的随机波动导致数控机床力变形误差,本文提出了一种恒负荷控制算法,根据实际加工负荷,对加工参数进行有效调整,在提高加工精度的同时使加工效率大幅度提高,并对加工负荷信号的检测、分析和处理作了详细的阐述。 相似文献
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行星齿轮传动系统复杂微弱故障的非线性特性 总被引:1,自引:0,他引:1
针对行星齿轮传动系统振动信号的非线性、非平稳性和故障特征微弱等特点,基于混沌理论对行星齿轮传动系统的正常、单一和多类耦合故障特性进行了综合分析与研究。用小波包算法对所采集的振动信号进行预处理;恰当选取最佳时延和最小嵌入维数重构相空间。在此基础上,用相图定性描述不同故障状态的故障类型;用关联维数和最大Lyapunov指数量化其各故障状态的特性和程度。研究结果表明:5种不同状态下的相图有一定的差异性;且故障越严重、故障耦合的越多,其关联维数和最大Lyapunov指数越大,混沌特性越强。因此,利用混沌的定性和定量方法可以有效识别行星齿轮传动系统的单一故障以及故障特征频率不重叠和故障特征频率重叠的两类耦合故障。 相似文献
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Extensive studies on rotor systems with single or coupled multiple faults have been carried out. However these studies are limited to single-span rotor systems. A finite element model for a complex rotor-bearing system with coupled faults is presented. The dynamic responses of the rotor-bearing system are obtained by using the rotor dynamics theory and the modern nonlinear dynamics theory in connection with the continuation-shooting algorithm(commonly used for obtaining a periodic solution for a nonlinear system) for a range of rub-impact clearances and crack depths. The stability and Hopf instability of the periodic motion of the rotor-bearing system with coupled faults are analyzed by using the procedure described. The results indicate that the finite element method is an effective way for determining the dynamic responses of such complex rotor-bearing systems. Further for a rotor system with rub-impact and crack faults, the influences of the clearances are significantly different for different rub-impact stiffness. On the contrary, the influence of crack depths is rather small. The instability speeds of the rotor-bearing system increase due to the presence of the crack fault. The results obtained using the new finite element model, presented for computation and analysis of dynamic responses of the rotor-bearing systems with coupled faults, are in accordance with measurements in experiment. The formulations given can be used for diagnosis of faults, vibration control, and safe and stable operations of real rotor-bearing systems. 相似文献