基于压电陶瓷的快刀伺服车削加工研究

利用matlab对微结构进行形貌仿真,生成含模拟量输出的数控加工程序。结合压电陶瓷的模拟量控制方法 ,使机床主轴、X轴和压电陶瓷三者同步工作,完成微结构的快刀伺服车削加工。加工了一个透镜阵列进行实验验证。     

基于混合驱动的大行程快速刀具伺服设计与控制

为获得高精度大行程快速刀具伺服（Long-range fast tool servo,LFTS）系统,以柔性铰链为运动导向机构,提出一种基于洛伦兹电磁力与压电混合串联驱动的LFTS系统构成策略。对于该混合驱动,基于洛伦兹力的音圈电机用于实现大行程运动,而高频响压电则对其进行高精度动态补偿。针对压电驱动,为提高系统输出刚度及寄生运动抑制能力,提出一种改进的具有完全对称构型的桥式柔性放大机构。两种驱动的垂直布置构型及压电驱动的完全对称性有效降低了驱动间动力学耦合。基于试凑法和智能优化算法,结合机-电-磁理论模型分别优化获得了音圈电机及压电驱动系统关键参数,并采用有限元仿真验证了设计的正确性。为获得高精度运动跟踪,提出音圈电机开环逆动力学控制及压电驱动闭环补偿LFTS整体运动误差的控制策略,借助所辨识系统动力学模型最优设计了相应控制器。最终,通过试验样机开闭环性能测试,验证了系统设计与控制策略的有效性。     

超精密快刀伺服加工复杂光学面形的技术研究

超精密快刀伺服加工技术适用于复杂面形光学零件的高效优质加工。文中通过分析快刀伺服加工的控制结构、压电陶瓷驱动性能,进行了超精密快刀伺服装置的设计与研制,建立了其传递函数模型。最后完成了典型复杂面形光学零件的加工试验,并对加工结果进行测试与分析,测试结果表明满足了设计的性能指标要求。     

基于Polaris控制的光学自由曲面快刀伺服技术研究

快刀伺服技术具有加工效率高、加工精度高、表面质量好等优点，被广泛运用于光学自由曲面加工。本文设计了音圈电机驱动的快刀伺服装置，建立了快刀伺服系统数学模型，构建加速度、速度复合前馈控制算法，进行了位置保持、阶跃、正弦跟踪的闭环性能测试，表明快刀伺服系统满足加工要求。基于快刀伺服系统控制器功能协调了刀具轨迹生成中快刀伺服装置运动和机床运动的同步关系，以离线计算加工方式实现快刀伺服技术。完成了典型非回转对称中的斜面加工实验，测得的粗糙度达到44 nm，表明设计研制的快刀伺服系统可以获得纳米量级的表面质量。     

一种压电陶瓷驱动电源的设计

快刀伺服加工技术在光学模具的精密制造中具有许多优势,而压电陶瓷驱动电源则是快刀伺服加工系统中重要的一环。针对快刀伺服系统的加工需要,设计了一种压电陶瓷驱动电源。该驱动电源以单片机为控制器,经过数模转换和低通滤波电路后,通过放大电路将信号放大,实现对压电陶瓷位移的控制。对线性放大电路进行了分析,通过对开环输出电阻的设置以及相位补偿,保证线性放大电路在驱动大容性负载时保持良好的稳定性。     

新型三自由度微操作平台的动力学性能研究

提出了一种新型三自由度柔性并联微操作平台,该平台采用压电陶瓷驱动器为驱动装置,以新型二级杠杆放大机构作为放大器来扩大压电陶瓷驱动器的输出行程,在功能上可以实现X轴、Y轴以及Z轴方向的微米范围内移动。首先通过拉格朗日方程建立了该三自由度柔性并联微操作平台的动力学模型,然后计算了该机构的理论固有频率,最后采用有限元软件对该微操作平台进行了模态分析。结果表明该机构的理论固有频率与有限元仿真分析中的第一阶模态结果相比其误差率仅为2.54%,验证了固有频率理论分析的正确性及可行性。     

高精度快刀伺服系统构建及其特性研究

快刀伺服是实现自由曲面光学曲面加工的方式之一.文中基于压电陶瓷为致动元件、柔性铰链为传动元件构建了快刀伺服系统.测试结果表明,研制的快刀伺服系统定位精度为4 nm以下,重复定位精度为4 nm以下,最大输出位移达到50 nm,运动频响在位移为20 nm时达到了 150 Hz.为后续快刀系统在自由曲面光学零件加工领域应用奠...     

压电陶瓷驱动的线性尺蠖驱动器设计与仿真

为了实现纳米操作中的精确定位,提出了一种压电陶瓷驱动的线性尺蠖驱动器。这个驱动器主要由1个柔性机构和3个压电陶瓷构成,其中一个压电陶瓷用来提供驱动力,另外两个用来交替夹紧线性导轨以用来实现尺蠖运动。建立了反映该尺蠖电机运动特性的理论模型,通过有限元仿真评估驱动器的性能和验证模型的有效性,研究了柔性机构的变形行为和相应的最大应力。     

柔性铰链微定位平台的设计

设计了一种以平行板铰链机构进行导向,以桥式机构进行位移放大的新型压电陶瓷驱动微定位平台。应用弹性力学和材料力学理论建立该平台的桥式放大机构和平行板铰链机构的理论模型,分析了平台的驱动力、输出位移、刚度和固有频率,并运用Matlab软件优化了桥式机构铰链长度、厚度,平行板铰链长度及厚度等几何参数,获得了微定位平台的最优值。对优化后的结果进行了有限元仿真,并搭建了测试系统对平台性能进行了测试。测试结果显示,理论分析与实验结果的最大误差为9.8%,有限元分析与实验结果的最大误差为4.2%,得到的结果验证了理论分析和有限元分析的正确性,实现了平台体积小,放大倍数高,位移输出大的设计目标。     

三维微细电火花加工伺服控制系统设计及实验研究

针对微细电火花加工伺服控制系统的要求,进行了微细电火花加工伺服控制系统总体设计.伺服控制系统特点是执行机构采用步进电机+压电陶瓷的宏微细合式驱动机构,实现了大行程和小步距的有机结合,能够提高电火花加工机床的加工性能.同时Z轴增加一个振动源,实现自动排屑和微调加工间隙.通过实验验证,证明系统运行良好,运动平台能够达到较高的精度,并实现了简单的极微细电火花加工.     

Multi-objective optimum design of fast tool servo based on improved differential evolution algorithm

The flexure-based mechanism is a promising realization of fast tool servo (FTS), and the optimum determination of flexure hinge parameters is one of the most important elements in the FTS design. This paper presents a multi-objective optimization approach to optimizing the dimension and position parameters of the flexure-based mechanism, which is based on the improved differential evolution algorithm embedding chaos and nonlinear simulated anneal algorithm. The results of optimum design show that the proposed algorithm has excellent performance and a well-balanced compromise is made between two conflicting objectives, the stroke and natural frequency of the FTS mechanism. The validation tests based on finite element analysis (FEA) show good agreement with the results obtained by using the proposed theoretical algorithm of this paper. Finally, a series of experimental tests are conducted to validate the design process and assess the performance of the FTS mechanism. The designed FTS reaches up to a stroke of 10.25 μm with at least 2 kHz bandwidth. Both of the FEA and experimental results demonstrate that the parameters of the flexure-based mechanism determined by the proposed approaches can achieve the specified performance and the proposed approach is suitable for the optimum design of FTS mechanism and of excellent performances.     

Design,fabrication, and testing of a 3-DOF piezo fast tool servo for microstructure machining

Fast tool servo (FTS) cutting has the superiority of high efficiency and high precision, which has attracted great attention from the field of microstructure machining. 3-degree-of-freedom (DOF) FTS device driven by piezoelectric (PZT) actuator, with high frequency, high precision, and low crosstalk property, are quite appealing for realizing complex microstructure machining. Therefore, a novel 3-DOF piezo-actuated FTS mechanism with high natural frequency and decoupling property is proposed in this paper. First, the static and dynamic models of the mechanism are established by using the compliance matrix and Lagrange equation methods, respectively. Then, the structural parameters of the mechanism are optimized by the genetic algorithm (GA) based Pareto multi-objective optimization algorithm. With the purpose of verifying the property of the above approach, the finite element analysis (FEA) acting on the designed mechanism has been carried out. Moreover, the modeling tasks in terms of cutting principle and trajectory planning are demonstrated in detail. Besides, a series of tests are carried out to verify the performance of the developed 3-DOF FTS. The testing results indicate that the working stroke of the mechanism is up to 40 μm, the natural frequency is above 873 Hz, and the mechanism has excellent motion decoupling performance (within 2%). The error of the trajectory tracking in all three directions are kept within ±0.7 μm. Finally, compared with the desired surface, the error of the machined microstructural surface is kept within ±1.5 μm, which further verifies its satisfactory performance towards ultra-precision FTS machining of microstructure.     

A flexure-based long-stroke fast tool servo for diamond turning

This paper describes the development of the fast tool servo (FTS) in detail and categorizes existing FTSs according to different principles. The characteristics and differences of these FTSs have been analyzed. A flexure-based long-stroke FTS system for diamond turning is presented with displacement range of 1?mm and bandwidths of 10?Hz. The vertical jump is about 0.045?μm, and the full stroke tracking error is less than 0.15%. A voice coil motor and a piezoelectric actuator are used as the driving elements, and two flexure hinges are developed as the guide mechanisms. The FTS utilizes a linear encoder and a capacitive sensor to measure the displacement of the tool for closed-loop control. The electromechanical design of the FTS and its motion analysis are described. Experimental tests have been carried out to verify the performance of the FTS system. This long-stroke FTS has the advantage of easy machining, high resonance frequency, and error compensation in y-axis direction.     

新型双臂菱形压电柔性机构理论设计与建模

针对目前传统菱形位移放大机构的输出刚度、固有频率和位移放大比无法同时提高的问题,提出了一种双臂复合菱形柔性机构,并介绍了其理论设计与建模方法。基于欧拉-伯努利梁理论和卡氏第二定理,推导出双臂复合菱形柔性机构的位移放大比和刚度解析模型,利用拉格朗日方程建立了该柔性机构的固有频率解析模型,并通过商业有限元软件验证了解析模型的准确性。根据理论计算结果,通过电火花切割工艺加工出复合柔性机构,并与相同尺寸参数的传统菱形位移放大机构进行实验比较研究。实验结果表明,压电双层臂柔性机构的固有频率为1330Hz,位移放大比为4.2,同时提高了固有频率和放大比。此外,所建立的位移放大比和固有频率力学解析模型可以为新型压电柔性机构的优化设计提供理论指导。     

Development of a piezoelectrically actuated two-degree-of-freedom fast tool servo with decoupled motions for micro-/nanomachining

The limited degrees of freedom (DOFs) of servo motions is an inherent deficiency in conventional, fast-tool-servo-(FTS)-assisted, diamond-turning, highly blocking applications of the FTS technique. In this paper, the concept of two-DOF FTS (2-DOF FTS)-assisted diamond turning is proposed and demonstrated. A piezoelectrically actuated 2-DOF FTS mechanism is developed to enable the cutting tool to move along two directions with decoupled motions. A novel guidance flexural mechanism constructed using the newly proposed Z-shaped flexure hinges (ZFHs) is introduced to generate motions along the z-axis, which is based on the bending deformation of the beams of the ZFHs. Additionally, using the differential moving principle (DMP), bi-directional motions in the x-axis direction can be achieved. Using the matrix-based compliance modeling method, the kinematics of the mechanism are analytically described, and the dynamics are also modeled using the Lagrangian principle. The theoretical results are then verified using finite element analysis (FEA). Certain increases in performances over conventional two-DOF flexural mechanisms are achieved: (a) a more compact structure with lower moving inertia, (b) theoretically decoupled motions of the output end, and (c) less than one actuator per DOF. To investigate the practical performance of the 2-DOF FTS system, both open-loop and closed-loop tests are conducted. Finally, the developed 2-DOF FTS technique is implemented to realize an innovative Pseudo-Random Diamond Turning (PRDT) method for the fabrication of micro-structured surfaces with scattering homogenization. The cutting results demonstrate not only the superiority of the concept but also the efficiency of the developed 2-DOF FTS system.     

菱形压电微位移放大机构的设计

为提高叠层压电陶瓷作动行程,并使之具有往复对称作动的特性,提出一种基于三角放大原理的菱形压电微位移放大机构。该机构以叠层压电陶瓷作为驱动元件,利用三角位移放大原理,在放大叠层压电陶瓷位移输出的同时,实现在平衡位置两侧的双向主动输出。提出了相应的驱动方法,实现了对该机构输出方向和大小的控制。分析了机构的工作原理,通过解析计算得到该机构的理论放大倍数为2.9,与所建立有限元模型通过仿真计算得到放大倍数2.5相近。制作了试验样机并进行了试验验证,结果显示:该机构在驱动电压为200V时最大输出位移为(32±16)μm,对叠层压电陶瓷位移输出的放大比例为2.4倍,与理论计算相近;频率响应试验表明信号频率对位移输出影响较小。提出的设计方案实现了位移放大和位移双向主动输出这两个预期目标。     

垂直型多级位移放大机构设计与力学解析建模

针对压电位移放大机构在垂直方向较难实现大行程、高频带宽度的问题,结合两个复合菱形机构、两个杠杆机构以及一个普通菱形机构,提出了一种垂直型多级位移放大机构。基于能量守恒方法和弹性梁理论建立了位移放大比和输入/输出刚度解析模型,根据拉格朗日方程推导了固有频率解析模型。通过有限元法对解析模型进行了验证,所建立的位移放大比解析模型有较高的预测精度,可为大行程垂直型柔顺平台的优化设计提供参考。与文献中的位移放大机构性能对比结果表明,提出的垂直型位移放大机构具有更好的静动态平衡性能,其位移放大比可达43.29,同时保持一个较高的固有频率561.28 Hz。     

压电位移放大机构的力学解析模型及有限元分析

研究了压电位移放大机构的运动学和动力学建模问题。基于能量守恒原理和弹性梁弯曲理论推导了桥式位移放大机构的位移放大比等静力学解析模型;在此基础上,通过拉格朗日方程建立了桥式位移放大机构的固有频率解析模型。通过有限元计算验证和分析了提出的解析模型的可行性和优越性,并与国内外典型的位移放大比数学模型进行了比较。结果表明:由于本文提出的模型考虑了位移放大机构的拉伸和弯曲变形,并且摒弃了国内外普遍采用近似几何关系进行数学推导的思路,因此所建立的位移放大比解析模型精度更高;固有频率解析计算结果与有限元模态分析结果的相对误差约为5%。得到的结果显示:本文给出的建模方法以及位移放大比、固有频率等解析模型可为柔性机构的优化设计和研制提供依据和参考。     

双向作动大行程二自由度稳像机构

针对光学稳像系统的双向动态大行程的设计要求,本文设计了一种可伸缩双向作动的压电作动器,并基于此压电作动器设计了二自由度稳像机构。压电作动器由一个收缩式三角位移放大机构和一个伸张式三角位移放大机构组成。位移放大机构可为压电平台提供足够的行程,柔性铰链可使平台结构更加紧凑。接着,利用有限元分析软件ANSYS对平台结构进行静力学仿真,模拟了平台的位移和应力变化。最后对原理样机进行了实验分析,实验结果显示所设计压电平台在低电压和低频率下有足够大的行程和足够快的响应速度,作动器在120V电压下的输出位移在67μm左右,基本满足稳像系统的性能要求,故平台结构的设计方案是可行的。     

全柔性机器人机构结构动力学分析方法研究

全柔性机器人机构是一种新型机构,多用于高精度的场合。由于其动力学性能会影响其终端的定位精度,因此,有必要对其结构动力学进行研究。具体将全柔性机器人机构作为结构体,分别采用理论简化建模、有限元和试验测试三种方法对其进行了结构动力学方面的研究,并进行了实例分析。首先通过理论简化建模计算出全柔性机器人机构的固有频率,采用商用有限元软件对该机构进行了模态分析,并对该机器人的模态频率进行了试验测试。有限元分析及试验结果均表明了简化模型计算结果有一定的精度。