Optimal design of a flexure-hinge precision stage with a lever

Lever mechanisms are usually used to enlarge output displacements in precision stages. A precision stage employing a lever mechanism and flexure hinges is analyzed theoretically, with bending in the lever considered. Relations between design parameters and magnification ratio, and the optimal values for the parameters to achieve a longer stage displacement are presented. Finite element analysis is used to verify the theoretical analysis. It is found that adjustment of lever dimensions and hinge stiffnesses can increase the stage travel range significantly.     

Compliance-based matrix method for modeling the quasi-static response of planar serial flexure-hinge mechanisms

A matrix method is proposed to model the direct and inverse quasi-static response of constrained/over-constrained planar serial mechanisms with flexure hinges under bending, axial, and shear planar (three-dimensional) loading and small-deformations. The method uses a basic three-point compliance matrix corresponding to one rigid link and one adjacent flexure hinge that are subjected to one point load. This matrix connects the displacements at a point on the rigid link with the load that is applied at another point on it, and the deformations of the flexure hinge at its distal point. The quasi-static model of planar serial flexure-based mechanisms with multiple links under single/multiple point loading results from linearly superimposing all relevant hinge-link-load triads defined by their three-point matrices. A displacement-amplification planar device with right circularly corner-fileted flexure hinges is studied using several refinement stages of the matrix method to generate a model whose predictions are confirmed by finite element simulation.     

Random misalignment and lever arm vector online estimation in shipborne aircraft transfer alignment

Shipborne aircrafts normally do not have regular position on the carrier. This would lead to large misalignment between the master strapdown inertial navigation system (M-SINS) and slave strapdown inertial navigation system (S-SINS) as well as random lever arm vector. It is critical for the accuracy of the transfer alignment. The large attitude error will make the linear alignment algorithm invalid. And the lever arm vector caused by the location difference will lead to the lever arm effect which is sensed by the accelerometers in the S-SINS. Therefore it is necessary for the shipborne aircraft to estimate the lever arm vector and misalignment before the transfer alignment takes place. In this paper, a new misalignment and lever arm vector online estimation method based on gyroscope, accelerometer measurement and filtering is presented. Sensor measurements of M-SINS and S-SINS will be recorded for a few seconds. Misalignment and the lever arm vector will be calculated from these measurements directly. The values will be filtered according to the chosen threshold of the error gain. Then a second stage estimation based on least square estimation will be applied to acquire a better result. Simulation results demonstrate the effectiveness of the estimation algorithm in the situation when both large misalignment and random lever arm vector exist.     

Study of dynamics of variable structure lever mechanisms

The problem of dynamics simulation is considered for cyclic lever mechanisms having a variable structure whose variations are caused by transition of the system from an idle run to a working one and vice versa. The study is performed using as an example the material transportation gear with lower and upper toothed racks for sewing machines used in the clothing, tanning and haberdashery, foot-wear, etc., industries.     

Design of lever mechanisms for shaping tire walls

A method is proposed for the calculation of spiral springs twisted into a ring, which are used in spring mechanisms to shape tire walls.     

Design and forward kinematics of the compliant micro-manipulator with lever mechanisms

This paper presents the forward kinematics of a five-bar compliant micro-manipulator. To overcome the limited displacement of such a flexure-based mechanism driven by piezoelectric actuators, lever mechanisms are utilized to enlarge the working range. The mechanical design of the micro-manipulator is firstly described. Mathematical formulations for the five-bar mechanism are described and the solutions are developed to decide the end-effector position in Cartesian space. The amplification factor of the lever mechanism is also derived based on the analytical solution of the four-bar linkages. The velocity of the end-effector is obtained by differentiating the forward position kinematic equation, and the local mobility index of the five-bar compliant mechanism is determined and analysed. Based on linearization of trigonometric functions and constant Jacobian matrix, numerical simulations are carried out to investigate the performance of the five-bar compliant manipulator and to determine the optimal geometric parameters for the configuration. The comparisons between the exact solution and simplified methodologies are conducted. Experiments are carried out to validate the established model and the performance of the developed micro-manipulator.     

A new type of compliant spatial four-bar (RSSR) mechanism

This paper presents a novel study on the analysis and design of a new type compliant spatial four-bar (RSSR) mechanism. To the best of our knowledge, any research on compliant spatial mechanisms which possesses out of plane motions is not available in the literature. This study introduces enumeration and novel approach for the analysis and design of such mechanisms. The analysis and design are performed with the pseudo-rigid-body model (PRBM). Since there are numerous applications of rigid spatial four bar mechanisms, it is strongly believed that a compliant version of such mechanisms may find many applications.     

新型精密磨削辅助微进给平台的研制及特性研究

设计了一种用于平面磨削主动控制的新型数控微进给工件平台.该平台由3个压电陶瓷(PZT)驱动器驱动,3个半圆形的弹性铰链构成的弹性环节实现对压电陶瓷驱动器的预紧.通过实验的方法研究了微进给平台的位移输出、静动态刚度等特性.     

Investigation of a 3-DOF micro-positioning table for surface grinding

A novel three degree of freedom numerically controlled micro-positioning table has been developed, optimized for applications such as improving the machining precision of precision grinders. The table consists of a moving platform, coupled to a base, three piezoelectric actuators and three capacitive sensors. An elastic structure with three notch-type flexure hinges both guides the platform and generates a preload for the piezoelectric actuators. The dimensions of the platform and flexure hinges and the position of flexure hinges are designed with the aid of finite element modeling to provide good stiffness with little bending deformation of the platform. The inverse model of the table is developed for numerical control. Experimental results are compared to the model predictions. The table has a natural frequency of 584 Hz, a resolution of 6 nm, an open loop control stiffness of 104 N/μm at the center of the moving platform and a closed loop control stiffness of 650 N/μm across the working area of the table.     

微动机器人的致动机理研究综述

MEMS是当前研究的一个热点，微机器人对于发展MEMS具有重要意义，也是MEMS的一项不可缺少的内容。微动技术是机器人学理论的一个重要分支，也是发展微机器人及相关微技术的基础。目前，各种新型微驱动器层出不穷，极大地推动了微机器人技术的发展。对于微动原理进行分析，从本质上弄清微动产生的机理，不仅可以丰富机器人学理论，还有可能使微动技术产生质的飞跃。从这一角度出发，对各种微动原理加以详细分析和比较，以期得出有意义的结论。     

Structural synthesis of a class of 2R2T hybrid mechanisms

Conventional overconstrained parallel manipulators have been widely studied both in industry and academia, however the structural synthesis of hybrid mechanisms with additional constraints is seldom studied, especially for the four degrees of freedom(DOF) hybrid mechanisms. In order to develop a manipulator with additional constraints, a class of important spatial mechanisms with coupling chains(CCs) whose motion type is two rotations and two translations(2R2T) is presented. Based on screw theory, the combination of different types of limbs which are used to construct parallel mechanisms and coupling chains is proposed. The basic types of the general parallel mechanisms and geometric conditions of the kinematic chains are given using constraint synthesis method. Moreover, the 2R2T motion pattern hybrid mechanisms which are derived by adding coupling chains between different serial kinematic chains(SKCs) of the corresponding parallel mechanisms are presented. According to the constraint analysis of the mechanisms, the movement relationship of the moving platform and the kinematic chains is derived by disassembling the coupling chains. At last, fourteen novel hybrid mechanisms with two or three serial kinematic chains are presented. The proposed novel hybrid mechanisms and construction method enrich the family of the spatial mechanisms and provide an instruction to design more complex hybrid mechanisms.     

坐标变换方法在高副机构分析中的应用

根据坐标变换理论,提出共原点和不共原点的两个坐标变换公式,直接应用这些公式即可对高副机构进行分析与综合。     

Coatings tribology—contact mechanisms and surface design

The fundamentals of coating tribology are presented by using a generalised holistic approach to the friction and wear mechanisms of coated surfaces in dry sliding contacts. It is based on a classification of the tribological contact process into macromechanical, micromechanical, nanomechanical and tribochemical contact mechanisms, and material transfer. The important influence of thin tribo- and transfer layers formed during the sliding action is shown. Optimal surface design regarding both friction and wear can be achieved by new multi-layer techniques which can provide properties such as reduced stresses, improved adhesion to the substrate, more flexible coatings and harder and smoother surfaces. The differences between contact mechanisms in dry, water- and oil-lubricated contacts with coated surfaces is illustrated by experimental results from diamond-like coatings sliding against a steel and an alumina ball. The mechanisms of the formation of dry transfer layers, tribolayers and lubricated boundary and reaction films are discussed.     

精密尺蠖压电进给装置步幅扩大机构的研究

压电陶瓷精密尺蠖微进给装置杠杆放大机构,是通过增大进给步幅来提高装置的速度性能。微尺蠖压电陶瓷进给装置的行走速度由行走的步幅和控制频率决定,理想状态是装置的行走步幅和控制频率同时达到最大。但这种状态是不可能达到的,应存在步幅和最大频率的协调。当利用杠杆增加装置的步幅时,会影响柔性铰链框架的弹性并影响装置的响应速度。因此,要对放大杠杆进行合理的设计,对杠杆放大比进行优化。     

简介德国并联机构之研究

简要介绍了作者对德国有关院校并联机构研究状况的实地考察结果。在依用途分类的前提下,分析各个并联机构的特点,指出其尚待完善之处,为我国在该领域的研究提供有借鉴。     

6-SPS型并联机构的混合坐标动力学建模

研究6-SPS型并联机构的动力学建模方法,提出了一种新颖的混合坐标动力学建模方法,根据6-SPS型并联机构特点,以四元数和笛卡尔坐标来定义6根支杆和动平台的方位及位置坐标,然后运用第一类拉格朗日方程建模方法建立了6-SPS型并联机构动力学模型,所建立的动力学模型形式简洁,体现了并联机构各向同性的特点,而且又发挥了四元数在数值计算上的优越性,因此具有适合计算机大规模编程计算的优点.     

连杆机构运动分析的解析设计

建立连杆机构运动分析的计算模型，并应用VB语言进行求解，提高设计精度。     

黎曼几何在并联机构动力学中的应用

介绍了采用黎曼几何的方法描述并联机构的动力学问题,推导出了一种十分简的动务学方程,黎曼几何的引入有助于我们对并联机构的动力学进行深入研究。