基于音圈电机的新型高速精密定位系统设计方法

设计了一种基于直线音圈电机直接驱动并采用新型弹性解耦机构的高速高精度XY精密定位平台。详细介绍了该装置的结构形式和动态设计方法,并对研制样机进行了性能测试。测试结果表明,该新型精密定位平台具有很高的速度、加速度和精度,能够适应集成电路封装业发展对封装设备提出的新要求。     

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。     

大行程精密定位平台偏摆误差的补偿方法

精密定位平台在导轨动连接处刚度较差,在高速高动态工作中这里易产生偏摆振动。为了减小偏摆误差对定位平台的影响,提高定位精度,通过对直线电机驱动、气浮导轨支撑和导向的高精度定位平台进行研究。根据定位平台偏摆误差的动态特性,采用偏摆误差补偿方法,设计一种偏摆误差检测系统,采用平尺和微位移传感器相结,具有高频响、非接触式的特点。设计了一种基于压电陶瓷驱动的x,y两维微位移补偿机构。同时,通过将气浮导轨滑块副简化成弹簧、质量和阻尼相结合的系统,推导出了定位平台两自由度的偏摆振动模型。基于误差补偿系统的偏摆误差补偿实验表明,精密定位平台的定位精度得到了较大提高,定位平台的定位精度优于2μm。     

高速精密平面定位机构的设计与应用

面向先进电子封装等领域对高速精密定位机构的需求，结合两种新型平面定位机构，对直接驱动并联机构的运动弹性动力学建模与仿真、基于扰动观测器的控制策略进行了研究。     

基于压电陶瓷驱动的并联微动机器人静力学及其微动平台的静刚度分析

并联微动机器人通过弹性铰链的弹性变形实现终端平台的微运动,静力学和静刚度是微动机器人必须解决的问题。充分考虑弹性铰链的弹性反力/力矩,对6-PSS并联微动机器人进行静力学分析,建立了压电陶瓷驱动力与微动平台外载的关系模型,并定义了微动机器人的驱动刚度矩阵。基于并联微动机器人的特殊性,定义了微动平台的刚度,通过静刚度分析推导出了微动平台刚度矩阵,为并联微动机器人结构刚度设计、弹性铰链刚度综合和动力学分析提供了理论基础。     

单自由度柔性微定位平台的设计与分析

针对微/纳精密操作定位精度要求,基于压电陶瓷驱动方法,设计了一类适用于面内精密定位工作的单自由度柔性微定位平台,采用单自由度柔性铰链实现机构的微/纳米级运动。通过构建柔性微定位平台的运动学模型得到了机构在铰链空间和笛卡尔空间中的位置映射关系,结合有限元仿真分析各位置柔性铰链的柔度特性对机构执行末端位移输出能力的影响,与位置理论计算结果比较说明其有效性。模态分析、驱动刚度分析为后续的动力学问题研究奠定了基础。     

基于多体动力学的弹簧操动机构的动态特性研究

利用多刚体系统动力学理论建立弹簧操动机构的动力学模型,研究弹簧操动机构在合闸过程中的动态特性,提示其运动学和动力学规律,然后基于ADAMS建立了该弹簧操动机构的虚拟样机,实现对该机构动态仿真分析,并对其动态特性进行分析研究.通过对弹簧操动机构的数值计算和动态仿真分析研究及两种方法分析结果的相互验证,为弹簧操动机构的动态优化设计和可靠性设计提供了理论基础.     

IC封装焊头机构接触力分析

针对IC封装焊头机构(bonder)高速运动、精密定位、微接触力的要求,运用虚拟样机技术,建立焊头机构虚拟样机模型.通过虚拟仿真,揭示了焊头部件的运动和动力学规律.为了保证取晶和固晶时的接触力要求,对弹簧参数和焊头与晶圆、引线框架的间隙进行优化.结果表明,焊头的位移控制精度则直接影响到接触力的大小,弹簧刚度则不仅影响接触力的大小,还影响它的稳定几性.     

一种垂直运动精密微定位平台的设计与分析

根据桥式放大机构和平行四边形导向机构相结合设计了一种新型的垂直运动精密微定位平台。利用卡式定理推导了微定位平台的最大行程、刚度及放大比,利用拉格朗日方程推导了微定位平台的动力学模型及其固有频率。采用有限元仿真软件分析微定位平台的动静力学特性,并与理论分析结果进行对比,两者结果吻合良好。制造了微定位平台的原型样机,并进行了实验验证,实验结果表明:垂直运动精密微定位平台的行程可达112.9μm,闭环分辨率为10 nm,可以用于显微镜聚焦系统的微调等垂直定位精度较高的场合。     

一种新型4自由度柔顺并联机构的设计和特性

设计一种新型4自由度精密微动平台,并对其静态和动态特性进行分析。在传统4-RRUR并联机构的基础上,采用替换法设计具有解耦的柔顺并联机构。采用有限元软件ANSYS对机构进行刚度和运动学分析,分析结果表明所设计的平台具有解耦的X和Y方向平动,并能实现4自由度微动。对机构进行灵敏度分析表明该柔顺机构的各个方向的位移灵敏度约为6μm/μm,说明平台灵敏。对机构进行模态分析,从振型可以看出该机构能实现4自由度方向的运动,并分析了在有和无预应力两种情况下的固有频率,两者差值范围为17.2%~52.4%,说明预应力对机构的固有频率有较大影响。     

基于应力刚化效应的动态特性可调微动平台设计新方法

针对现有基于柔性铰链的微动平台动态特性受材料特性、设计制造等误差影响,难以满足精密微动平台对动态响应（特别是可变频率操作）的高要求,基于应力刚化效应,提出了动态特性可调的微动平台设计新方法,推导预应力作用下一端固定一端导向梁的等效刚度和质量公式;基于对称布置假设,建立含有弹片式柔性铰链(下面简称弹片)组数(离散变量)和截面尺寸(连续变量)的离散连续变量复合优化模型,释放承载刚度约束,获得截面尺寸含有弹片组数变量的精确解系列,分析了给定预应力下不同弹片组数微动平台的承载刚度和频率调节范围,从而通过承载刚度约束和频率调节范围要求确定弹片组数。通过数值算例,验证了推导计算模型求解精度和所提设计方法的应用有效性。计算结果表明,与有限元分析结果相比,本模型的计算结果相对误差小于2%,实现了给定工作刚度、频率和承载刚度约束的微动平台最优结构设计。所提方法实现了刚度和频率大范围的调整,不但降低了加工精度要求,还为动态特性自适应匹配的智能微动平台提供一种实现途径。     

A novel precision positioning table utilizing impact force of spring-mounted piezoelectric actuator—part II: theoretical analysis

A simple mechanical vibration model was formulated to analyze the dynamic characteristics of the precision positioning table utilizing a spring-mounted piezoelectric actuator. The formulated model was validated by comparing the results of numerical simulations with the experimental data of Part I. The performance of the precision positioning table was predicted by changing the parameters of mass ratio and stiffness of spring. It is found that the analytic method described in this paper can provide an effective means in designing the precision positioning table utilizing a spring-mounted piezoelectric actuator.     

Dynamic modelling of a flexure-based mechanism for ultra-precision grinding operation

This paper presents the dynamic modelling and performance evaluation methodologies of a flexure-base mechanism for ultra-precision grinding operation. The mechanical design of the mechanism is briefly described. A piezoelectric actuator is utilized to drive the moving platform. A flexure-based structure is utilized to guide the moving platform and to provide preload for the piezoelectric actuator. By simplifying the Hertzian contact as a linear spring and damping component, a bilinear dynamic model is developed to investigate the dynamic characteristics of the flexure-based mechanism. Based on the established model, the separation phenomenon between the moving platform and the piezoelectric actuator is analyzed. The influences of the control voltage and the preload stiffness on the maximum overshoot are extensively investigated. The slope and cycloidal command signals are utilized to reduce and/or avoid the overshoot of such flexure-based mechanism for rapid positioning. The effects of the rising time of the command signals on the maximum overshoot and the settling time are also explored. Experiments are performed to verify the established dynamic model and the performance of the developed flexure-based mechanism.     

Analysis on the performance of the SLIP runner with nonlinear spring leg

The spring-loaded inverted pendulum(SLIP) has been widely studied in both animals and robots.Generally,the majority of the relevant theoretical studies deal with elastic leg,the linear leg length-force relationship of which is obviously conflict with the biological observations.A planar spring-mass model with a nonlinear spring leg is presented to explore the intrinsic mechanism of legged locomotion with elastic component.The leg model is formulated via decoupling the stiffness coefficient and exponent of the leg compression in order that the unified stiffness can be scaled as convex,concave as well as linear profile.The apex return map of the SLIP runner is established to investigate dynamical behavior of the fixed point.The basin of attraction and Floquet Multiplier are introduced to evaluate the self-stability and initial state sensitivity of the SLIP model with different stiffness profiles.The numerical results show that larger stiffness exponent can increase top speed of stable running and also can enlarge the size of attraction domain of the fixed point.In addition,the parameter variation is conducted to detect the effect of parameter dependency,and demonstrates that on the fixed energy level and stiffness profile,the faster running speed with larger convergence rate of the stable fixed point under small local perturbation can be achieved via decreasing the angle of attack and increasing the stiffness coefficient.The perturbation recovery test is implemented to judge the ability of the model resisting large external disturbance.The result shows that the convex stiffness performs best in enhancing the robustness of SLIP runner negotiating irregular terrain.This research sheds light on the running performance of the SLIP runner with nonlinear leg spring from a theoretical perspective,and also guides the design and control of the bio-inspired legged robot.     

二自由度微定位平台的研制

研制了一台压电陶瓷驱动和弹性铰链导向的一体化微定位平台,该微定位平台具有高刚度、高响应速度和高分辨率等优点。为了克服压电陶瓷驱动器伸长量较小的不足,采用杠杆放大机构增加微定位平台的位移输出。考虑驱动电路的影响,建立了微定位平台的机电耦合模型。通过试验研究了微定位平台的静动态特性,试验结果表明微定位平台的分辨率为5 nm,固有频率分别为143 Hz和180 Hz。该微定位平台可应用于纳米级的微定位。     

DEVELOPMENT OF A 3-DOF MICROOSITIONING WORKPIECE TABLE

In order to achieve active grinding control,a novel numerical control micropositioning workpiece table with a resolution of 6 nm has been developed.The table is driven by three piezoelectric actuators mounted on the base.An elastic structure with three half-notch flexure hinges is designed to apply preload to the piezoelectric actuators.The position of flexure hinges is also elaborately designed with consideration to reduce the bending deformation of the moving part.Three capacitive sensors are used to form close loop control system.Considering the table as a damped 3-DOF mass-spring system,the models of static and dynamic stiffness and error owing to the action of external forces have been established.In order to make the table have high resolution and positioning accuracy,an error compensation algorithm is implemented by using the established models.The experimental testing has been carried out to verify the performance of the workpiece table and the established models of the micropositioning workpieee table.     

DEVELOPMENT OF A 3-DOF MICRO-POSITIONING WORKPIECE TABLE

In order to achieve active grinding control, a novel numerical control micropositioning workpiece table with a resolution of 6 nm has been developed. The table is driven by three piezoelectric actuators mounted on the base. An elastic structure with three half-notch flexure hinges is designed to apply preload to the piezoelectric actuators. The position of flexure hinges is also elaborately designed with consideration to reduce the bending deformation of the moving part. Three capacitive sensors are used to form close loop control system. Considering the table as a damped 3-DOF mass-spring system, the models of static and dynamic stiffness and error owing to the action of external forces have been established. In order to make the table have high resolution and positioning accuracy, an error compensation algorithm is implemented by using the established models. The experimental testing has been carried out to verify the performance of the workpiece table and the established models of the micropositionin     

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.     

A comparative study on the dynamics of high speed spindles with respect to different preload mechanisms

This paper presents the effects of bearing preload mechanisms on the dynamic performance of high speed spindles. The comparisons of two main types of bearing preload????constant?? and ??rigid????mechanisms are provided using a mathematical model as well as experiments. Based on the Timoshenko beam element theory coupled with a nonlinear model of angular contact ball bearings, the dynamics of the spindle shaft, housing, and bearings system is modeled as a nonlinear function of preload mechanism and amplitude, spindle speed, and external cutting loads. The mathematical model of the spindle is experimentally validated by comparing the predicted and measured static displacements, mode shapes, frequency response functions, and natural frequencies under different conditions. The performance of spindles under rigid and constant force preload is investigated systematically using a mathematical model under various conditions. It is shown, among other things, that at high speeds and under cutting loads the rigid preload mechanism is more efficient in maintaining the dynamic stiffness of spindles than constant preload.