一种精密平台的柔性铰链设计和有限元验证

精密平台是一种能够提供微位移的高精度工作平台,柔性铰链作为传动机构,在精密平台设计中广泛应用。柔性铰链是决定平台性能的关键,柔性铰链的结构形式和尺寸参数影响着定位精度的高低。设计了一种叠加支链形式的柔性铰链结构,推导了基于该柔性铰链的二维精密平台的工作刚度、耦合刚度、耦合系数、铰链应力等性能指标的解析公式,并采用了有限元软件对性能指标进行了验证。仿真表明,两者具有良好的一致性,为应用于精密平台的柔性铰链设计提供参考。     

基于PMAC定位平台的定位精度与误差补偿研究

气浮精密定位平台在运动的过程中需要有高的运动精度与良好特性,而决定其运动精度的则为平台的定位精度与重复定位精度。研究了基于PMAC的气浮精密定位平台的精密定位控制技术,利用Renishaw激光干涉仪对精密气浮定位平台的定位精度与重复定位精度进行实验研究,分析在不同反馈传感器、不同控制参数下定位平台定位精度与重复定位精度的影响规律,在此基础上通过统螺距误差补偿与间隙补偿公式换算得出补偿数据,利用补偿数据对定位平台进行误差补偿。研究结果表明,通过对误差补偿方法的使用,定位平台的定位精度与重复定位精度分别提高了80%和20%。     

二维高带宽低耦合纳米定位平台设计与实验

纳米尺度研究的发展对原子力显微镜的核心运动部件——纳米定位平台的定位精度与扫描速度提出了更高要求。针对平台运动耦合与谐振频率两项关键性能展开研究,设计了一种新型基于压电陶瓷驱动的二维高带宽低耦合纳米定位平台。结构设计上,首先提出高刚度并联解耦结构,然后基于内外侧柔性铰链刚度解耦假设,确立了高刚度低耦合设计方案。为进一步提升平台谐振频率,建立尺寸参数优化模型,以平台一阶谐振频率为优化目标进行优化设计。优化结果与有限元仿真结果误差小于6%,验证了设计方法的准确性。最后,加工样机并搭建实验系统。性能实验结果证明本文设计平台达到高带宽低耦合设计目标。平台性能与同类型现有平台相比,谐振频率提升20%,静态耦合降低80%,动态耦合降低30%,有助于原子力显微镜性能提升。     

具有耦合补偿功能的大行程二维柔性平台

设计了一种基于双级复合平行板簧结构的大行程二维并联微位移平台,以解决二维柔性平台尺寸大、行程小,运动耦合误差大,运动性能受加工误差影响等问题。设计的微位移平台在每个运动方向均采用两个音圈电机同时驱动,通过调节两音圈电机信号比例来补偿加工误差造成的运动耦合误差,完成X和Y方向的运动解耦,从而降低系统对加工精度的依赖程度。根据卡氏第二定理建立了平台力学模型,优化了平台尺寸参数,并利用有限元仿真对设计的平台性能进行验证。最后,搭建了微位移定位系统实验平台。实验结果表明:设计的柔性平台行程与平台尺寸占比大,定位精度高,运动解耦性能得到大幅改善,实现了±2.25mm×±2.27mm工作行程,工作行程与平台尺寸占比约为1.73%,运动耦合误差小于0.27%。     

直圆柔性铰链加工误差对刚度的影响和有限元验证

柔性铰链是一种行程小,定位精度高的传动机构,对加工精度有较高的要求。针对柔性铰链关键尺寸3种不同的加工误差,通过建模和受力分析,推导了直圆柔性铰链存在加工误差时的转动刚度计算公式,以数值积分方法计算刚度误差,并拟合出一种无量纲的刚度误差公式。同时以有限元仿真对计算公式进行验证,对误差曲线进行比较,结果表明了较好的一致性,为柔性铰链的设计和加工提供参考。     

低成本柔顺板式精密定位平台的理论与试验

基于柔顺薄板的弹性变形原理,提出一种低成本、整体式柔顺精密定位平台的设计方法。设计一种平板弹簧机构,使平台能够在较低精度驱动器的驱动下获得高精度的位移输出,从而大幅度降低精密定位平台的成本。建立平台的刚度模型,分析驱动器的精度与平台的定位精度之间的相互关系。最后,分析加工误差对平台定位精度的影响,得出影响定位精度的关键结构参数。通过试验测试,得出驱动器的输入位移和精度分别为4 mm和10m,平台的输出位移和精度分别为9 m和40 nm,线性度为0.33,从而验证了该设计方法的正确性。该平台结构紧凑,成本低,具有很好的性价比,应用前景广阔。     

三种两自由度柔顺精密定位平台的性能对比与分析

针对传统的缺口型和直片型柔性铰链平台行程不足的特点,设计了一种波纹簧片型柔性铰链,并在此基础上设计了由电磁驱动的两自由度柔顺精密定位平台。基于波纹簧片型、缺口型和直片型柔性铰链平台的特点建立有限元模型分析了这三种平台的静态和模态性能,包括行程,固有频率等。利用电磁驱动作为定位平台的输入驱动,综合对比了三种平台的实际行程,耦合位移,重复定位精度等性能,验证了有限元分析的正确性。结果表明,相比于缺口型和直片型柔性铰链平台,基于波纹簧片型柔性铰链的两自由度柔顺精密定位平台具有行程大,定位精度高的特点,对于柔顺精密定位平台的研究具有重要的参考价值。     

基于神经网络的宏/微双驱动运动平台误差预测及补偿技术研究

宏/微双驱动平台是一种用于微切削加工的高精度切削平台,其定位精度受多种因素影响。为提高宏/微双驱动定位运动平台的定位精度,提出基于BP神经网络进行宏/微双驱动运动平台定位误差预测的方法。测量运动平台的定位精度,从而建立BP神经网络误差预测模型,并运用该模型对宏/微双驱动运动平台进行定位误差预测试验,最终证明BP神经网络定位误差预测模型精度高、抗变换性能好,适用于对宏/微双驱动运动平台的定位误差进行误差预测及补偿,使得宏/微双驱动平台达到10nm级精度设计要求。     

并联微动机构的柔性设计

由于并联微动机构应用在特殊场合,故对其定位精度提出了极高的要求.运动副的间隙和摩擦是影响机构精度的主要因素,提出了采用无间隙、无摩擦的柔性铰链作为微动机构的运动副.通过分析柔性铰链结构尺寸与性能的关系,合理选择了铰链材料和几何尺寸.并以带柔性铰链的Stewart六自由度平台为设计实例,证明了柔性铰链在微动机构中的应用是成功的.     

基于桥式柔性铰链多误差源的数学建模

利用快刀伺服系统加工可获得纳米级的微结构,桥式柔性铰链是最关键的零件之一,其柔性铰链的误差度直接影响零件的加工精度。通过对多误差源的分析,探索每个误差源对精度的影响程度。包括过对桥式柔性铰链关键尺寸的加工误差,特别是对敏感度较高的长度、宽度、厚度加工误差的分析,建立起关键尺寸与加工精度的数学模型;分析温度变化,建立基于神经网络的加工误差数学模型,并提出温度补偿的策略;分析重力等原因引起的误差变形,建立由于重力引起变形量与加工精度的数学模型。将上述的多误差源的数学建模运用到设计和制造中,能从源头上减少误差对加工精度的影响程度,提高快刀伺服系统加工微结构零件的尺寸精度和表面粗糙度。     

Modelling and parameter design of a 3-DOF compliant platform driven by magnetostrictive actuators

Precision platforms composed of smart-material-based actuators and compliant mechanisms show advantages of high accuracy and fast response. This research focuses on a 3-degree-of-freedom compliant platform driven by magnetostrictive actuators. A parameterized physical model is established for the platform with consideration of three kinds of coupling effects. The magneto-mechanical coupling of the magnetostrictive actuator is described by a modified Jiles-Atherton model. The structural coupling of the platform is characterized in the process of stiffness matrix modelling and coordinate system transformation of the compliant components. The coupling between the magnetostrictive actuator and the compliant structure is considered in the overall actuation model. Parameter design is performed based on the numerical simulation of the proposed model. Due to the coupling effect, the dimensions of the compliant amplifier affect both the amplification ratio and the actuation stroke of the actuator. Thus, a combined optimization is essential to obtain the optimal design. The influences of the key dimensions on platform stiffness and actuation performances are demonstrated. With optimized key dimensions, the parasitic displacements can be effectively reduced at very little cost of the moving strokes. Open-loop experiments are taken to verify the accuracy of the proposed physical model, and closed-loop experiments are performed to demonstrate the platform performance on precision positioning. The main errors are caused by the friction in a sliding pair and the inertia of the loads.     

Preload characteristics identification of the piezoelectric-actuated 1-DOF compliant nanopositioning platform

Packaged piezoelectric ceramic actuators (PPCAs) and compliant mechanisms are attractive for nanopositioning and nanomanipulation due to their ultra-high precision. The way to create and keep a proper and steady connection between both ends of the PPCA and the compliant mechanism is an essential step to achieve such a high accuracy. The connection status affects the initial position of the terminal moving plate, the positioning accuracy and the dynamic performance of the nanopositioning platform, especially during a long-time or high-frequency positioning procedure. This paper presents a novel external preload mechanism and tests it in a 1-degree of freedom (1-DOF) compliant nanopositioning platform. The 1-DOF platform utilizes a parallelogram guiding mechanism and a parallelogram load mechanism to provide a more accurate actual input displacement and output displacement. The simulation results verify the proposed stiffness model and dynamic model of the platform. The values of the preload displacement, actual input displacement and output displacement can be measured by three capacitive sensors during the whole positioning procedure. The test results show the preload characteristics vary with different types or control modes of the PPCA. Some fitting formulas are derived to describe the preload displacement, actual input displacement and output displacement using the nominal elongation signal of the PPCA. With the identification of the preload characteristics, the actual and comprehensive output characteristics of the PPCA can be obtained by the strain gauge sensor (SGS) embedded in the PPCA.     

基于虚功原理的3-RRPR柔性精密定位工作台动力学分析

为了实现柔性精密操作系统的高频控制,提出一种新型空间柔性并联精密定位工作台系统,该工作台采用多个压电陶瓷驱动方式,通过半圆形凹槽单自由度柔性铰链的弹性变形实现末端执行件3平动自由度的主动调整.根据机构伪刚体模型,采用矢量闭环方法建立其位置、速度以及加速度方程,并结合柔性铰链弹性应变能,采用虚功原理方法进行动力学分析,推...     

一种外LET柔顺半铰的动力学建模与分析

对一种外LET柔顺半铰进行建模与动力学特性分析。采用斜率不连续的绝对节点坐标法（ANCF）建立了该柔顺半铰系统动力学方程;对外力作用下半铰中心线和外轮廓的运动变形进行仿真,与实验结果对比,证明了绝对节点坐标法对柔顺半铰动力学建模的有效性;进一步分析了半铰外形尺寸变化对其变形规律的影响。     

A 3-prismatic-revolute-spherical compliant parallel platform for optoelectronic packaging

To align the optical channels of optoelectronic appliances, a 3-prismatic-revolute-spherical (3-PRS) compliant parallel platform (CPP) is proposed in this work. The platform has special large stroke compliant joints. Attention is paid to the establishment of the inverse kinematics model and the analysis of the parasitic motion (PM) of the platform. A prototype of the platform is also presented, and its accuracy is experimentally evaluated. Besides, the platform is employed as a 3 degree-of-freedom (DOF) platform for optoelectronic packaging. Furthermore, the closed-loop control strategy requires merely one optical power meter to avoid the use of complex multiple DOF detection devices. In this respect, the influence of the precision of inverse kinematics solution on the optoelectronic packaging is reduced. Moreover, a compensation rule is employed to minimize the effect of PM on the motion accuracy of the platform. The results show that the proposed 3-PRS CPP is highly efficient for optoelectronic packaging.

     

整体式空间3自由度精密定位平台的优化设计与试验

根据柔顺薄板的弹性变形原理,设计一种整体式空间三自由度柔顺并联微动平台.分析该平台的输入耦合特性,对三种输入耦合形式对定位精度的影响进行讨论.基于有限元法,给出平台的刚度模型,对平台的结构尺寸进行优化设计,并通过ANSYS仿真分析验证优化结果的正确性.在此基础上进一步建立平台的位置正解和位置逆解方程,对平台的定位精度进行试验研究,提出一种基于理论分析模型的试验修正方法,该方法能有效提高平台的定位精度,研究表明该平台具有亚微米级的定位精度.     

三支链六自由度并联柔性铰微动机器人的研究

提出了一种过程中采用的新型三支链六自由度并联微动机器人结构。采用两端分别带有柔性球铰和柔性旋转铰的支杆以简化结构,整体加工包含三个二自由度单元的基平台来有效减小装配误差,并用压电陶瓷驱动弹性平板获得高分辨率高精度。根据运动影响系数理论对其运动学进行分析,求出了其平动台、支杆和柔性铰链的速度表达式。考虑柔性铰链的弹性变形,基于虚功原理建立了其刚度模型。 分析了此类并联微动机器人的设计目标和柔性铰链设计原则,采用模块化精密定位控制器设计了控制系统。实验结果表明,所设计的微动机器人可达到纳米级精度, 简化了六支链六自由度并联微动机器人的复杂结构,减小了装配误差。     

Analysis and experiments of a novel and compact 3-DOF precision positioning platform

A novel 3-DOF precision positioning platform with dimensions of 48 mm×50 mm×35 mm was designed by integrating piezo actuators and flexure hinges. The platform has a compact structure but it can do high precision positioning in three axes. The dynamic model of the platform in a single direction was established. Stiffness of the flexure hinges and modal characteristics of the flexure hinge mechanism were analyzed by the finite element method. Output displacements of the platform along three axes were forecasted via stiffness analysis. Output performance of the platform in x and y axes with open-loop control as well as the z-axis with closed-loop control was tested and discussed. The preliminary application of the platform in the field of nanoindentation indicates that the designed platform works well during nanoindentation tests, and the closed-loop control ensures the linear displacement output. With suitable control, the platform has the potential to realize different positioning functions under various working conditions.     

An analysis of overcut variation and coupling effects of dimensional variable in EDM process

In the electrical discharge machining (EDM) process, the overcut greatly affects the precision and accuracy of the workpiece dimensions. However, the overcut and the final workpiece dimensions are difficult to predict due to the non-linear, complex relationship among the electrode wear, the electrode diameter, electrical discharging parameters, and the machine positioning accuracy. In the present study, the variation of the side overcut and the bottom overcut, the electrode dimensions, the spark hole dimensions, and the machine positioning accuracy in the EDM process are investigated. Variance analysis is used in a batch process under different electrical discharging parameters. The experiment results show that the coupling effect between the electrode diameter and spark hole diameter is an important factor for estimating the variation of the side overcut in the EDM process. With inclusion of the coupling effects, the predicted variation of side and bottom overcut in a batch EDM process and the EDM machine positioning accuracy is shown to be in good agreement with experimental results.     

长行程精密定位平台的设计

音圈电机与柔顺机构的结合,设计了一个在固定运动范围内具有高精度定位能力的精密定位平台,分析了平台参数的确定方法。给出了提高定位平台稳定性的措施。