长跨度孔系直径与同轴度误差测量系统

针对飞机铰链件长跨度、小直径孔系的直径和同轴度误差高精度测量问题,研制了基于光电传感器的综合测量系统。多功能测头中的直流电机驱动自定心机构确定孔截面测量位置,光电编码器记录电机有效转动量,通过与标准环规进行比较间接测量各孔直径。以激光作为准直基准,安装在多功能测头前端的PSD检测激光光斑位置以确定各孔截面中心坐标,并进而评定出孔系的同轴度误差。使用该测量系统完成了孔系直径测量试验和PSD光斑检测线性及重复性试验。试验结果表明,与三坐标测量机测量结果相比,孔径测量相对误差小于10μm,PSD光斑位置检测重复性误差小于13μm,具备了较高的检测精度。     

光电位置敏感探测器非线性误差校正方法研究

位置敏感探测器(PSD)以其分辨率高、时间响应性好的优点在光电检测领域得到了广泛的应用,但是PSD在生产过程中产生的非线性误差极大的影响了测量精度和范围,因此对PSD进行必要的非线性误差修正可以大大提高其测量精度和可靠性。     

基于位置敏感器件的液位检测系统及其数据处理

精确测量光固化成型设备中光敏树脂的液面位置是确保成型精度的关键,根据激光三角法原理设计基于PSD的液位检测系统,采用点激光和一维位置敏感器件组成液位检测系统。通过测量点激光在PSD上的位移量来获取液面位置的变化量,在分析PSD误差特点基础上,通过优化结构设计、信号采集、检测系统标定和实时数据处理4个方面来提高检测精度。实际测试表明:液位检测系统量程中间位置的误差小于0.27%,两边误差小于0.4%,可满足系统测量精度要求。     

基于PSD的激光跟踪仪光电瞄准技术应用与研究

光电瞄准与定位技术是空间运动目标动态跟踪测量的关键技术,起到目标捕获与运动位置偏差精确指向作用。基于光电位置传感器(PSD)对激光跟踪仪的光电瞄准和跟踪定位控制技术进行了分析研究与设计,提出了光电瞄准控制方案,设计了探测光路,分析了PSD误差修正与信号处理。经过实际样机测试,静态定位测量精度达到6μm,随机动态跟踪测量速度大于1 m/s。     

位置敏感探测器非线性误差修正实验研究

位置敏感探测器(position sensitive detector,PSD)以其分辨力高、时间响应性好的突出优点在光电检测领域得到了广泛的应用,但PSD在制造过程中产生的非线性误差很大程度上降低了它的测量精度和范围。利用双一次插值法对PSD进行了非线性误差修正,阐述了实验的设计原理和操作。对非线性误差修正结果的分析表明,通过采用双一次插值法进行误差修正,B区的测量误差显著减小,大大提高了PSD的测量精度和可靠性。     

超精密机床激光干涉测量系统误差分析及补偿

详细分析了超精密机床加工中,激光测量系统误差组成及其产生机理,给出了有效的修正和补偿手段.影响激光测量系统精度和重复精度的主要误差因素可分为3类：内部误差、环境误差和安装误差.通过实例分析精密机床四轴激光测量系统,设计出了四轴激光测量光路,实现超精密工作台的X、Y、Rz三自由度位置反馈,给出了影响测量精度的误差因素以及对系统精度的影响大小.     

加工中心三维体积定位误差的理论及其激光测量

二十年前,机床最大的定位误差为丝杠的螺距误差及丝杠的热膨胀误差,但时至今日上述的大部分误差已被大幅度降低,因此机床的主要误差转而变成垂直度误差和直线度误差。所以,为了达到高的机床三维空间定位精度,机床上所有的3个位移误差、6个直线度误差和3个垂直度误差都得测量与补偿。目前,光动公司已为机床三维体积定位误差测量发明并研制了革命性的激光矢量测量技术(美国专利6,519,043,2/11/2003)。使用这种测量,仅需数个小时就可完成对机床误差的测量,而使用目前常规的激光干涉测量可能需要数日才能完成。因此,为了获得更高的加工精度,机床三维体积定位误差测量和补偿变得越来越紧迫和必要。本文首先介绍三维体积定位误差测量的基本理论及其公式推导,然后介绍LDDM硬件及其调整、数据采集和分析,最后给出基于激光矢量测量技术的体积斜线测量的结果。还要讨论这种新技术对三维体积定位精度、机床业的影响。     

多轴数控机床几何误差的软件补偿技术

论述了在“华中Ｉ型”数控系统中开发的数控机床几何误差的软件补偿技术。分析了各轴的误差元通过运动链传播的建摸问题和其对切削刀具在机床工作空间中的姿态误差的影响;建立了机床结构的每个误差元和切削刀具相对工件位置误差相联系的通用数学模型;采用激光干涉仪直接测量的方法来获取误差模型中各个误差元参数,提出了一种测量机床运动部件滚摆角的新方法;测量点的误差参数被存储在计算机内,在测量点之间采用线性插值来获得补偿点的误差参数。数控系统每８ｍｓ中断一次,读取与补偿点相关的位移和转动误差参数以及刀具的参数,利用误差模型计算刀具相对工件的误差在各个运动轴上的误差分量,该误差分量被数控系统叠加到各运动轴的指令位移上,使各个运动轴产生附加的运动,从而实现数控机床几何误差的软件补偿。对比试验表明该补偿技术能使数控机床的几何误差减小７０％。     

HP5528A频激光干涉仪动态误差补偿

建立了ＨＰ５５２８Ａ双频激光干涉仪的动态误差模型，根据模型可补偿动态误差，使ＨＰ５５２８Ａ双频激光干涉仪可用于测量高速运动物体的位移。     

兆瓦级风电齿轮箱低速中间轴的动态误差分析

针对传动系统激励与响应不同步问题,不计传动部件阻尼因素,在只考虑构件柔性的前提下,对1.5MW风电齿轮箱内悬浮支撑的低速中间轴激起的系统动态误差进行了研究。采用达朗贝尔原理建立动态误差数值递推模型,应用MATLAB对模型进行模拟和分析,并利用等效系统对比验证。分析结果表明:齿轮箱动态误差不仅同系统固有参数相关,其幅值还受到外载荷的影响;同步误差分量和自由振动误差分量线性叠加构成了系统动态误差,其中自由振动误差分量会引起齿轮啮合的随机波动,若增大低速中间轴刚度,可补偿部分同步误差,进而提高传动系统稳定性和传动精度。     

Dynamic compensability and compensability measure for robot systems with structural flexibility

In this paper, we are concerned with using the joint torque to compensate for the end-effector acceleration error caused by links flexibility. A new concept of dynamic compensability of flexibility based on relationships between joint control torque, acceleration of flexible link and acceleration of end-effector is introduced. Conditions for the existence of dynamic compensability are given, and proprieties of dynamic compensability are investigated. A dynamic compensability measure and dynamic compensability ellipsoid are proposed to quantify the degree of dynamic compensability. Examples are given to illustrate this concept.     

Maximum allowable dynamic load of flexible mobile manipulators using finite element approach

In this paper a general formula for finding the maximum allowable dynamic load (MADL) of flexible link mobile manipulators is presented. The main constraints used for the proposed algorithm are the actuator torque capacity and the limited error bound for the end-effector during motion on a given trajectory. The accuracy constraint is taken into account with two boundary lines which are equally offset due to the given end-effector trajectory, while a speed-torque characteristics curve of a typical DC motor, is used for applying the actuator torque constraint. Finite element method (FEM), which is able to consider the full nonlinear dynamic of mobile manipulator is applied to derive the kinematic and dynamic equations. In order to verify the effectiveness of the presented algorithm, two simulation studies considering a flexible two-link planar manipulator mounted on a mobile base are presented and the results are discussed.     

Maximum allowable dynamic load of flexible mobile manipulators using finite element approach

In this paper a general formulation for finding the maximum allowable dynamic load (MADL) of flexible link mobile manipulators is presented. The main constraints used for the proposed algorithm are the actuator torque capacity and the limited error bound for the end-effector during motion on a given trajectory. The accuracy constraint is taken into account with two boundary lines which are equally offset due to the given end-effector trajectory, while a speed-torque characteristics curve of a typical DC motor is used for applying the actuator torque constraint. The finite element method (FEM), which is able to consider the full nonlinear dynamics of mobile manipulators, is applied to derive the kinematic and dynamic equations. In order to verify the effectiveness of the presented algorithm, two simulation studies considering a flexible two-link planar manipulator mounted on a mobile base are presented and the results are discussed.     

柔性冗余度机器人减振运动规划研究

由于柔性冗余自由度机器人具有冗余特性 ,因此在保证机器人实现预定工作任务的情况下 ,可以通过规划机器人各关节的自运动规律 ,从而改善机器人的动力学性能。本文提出了一种冗余关节规划方法 ,该方法为全局优化方法 ,具有可实现性、易控制和计算量小的特点 ,而且可以保证机器人工作结束后各关节的自运动速度为零 ,从而避免由于终态自运动的存在而使原优化效果遭到破坏。     

OPTIMAL CONTROL OF THE FLEXI- BLE LINK MANIPULATOR WITH CONTROLLABLE LOCAL DEGREES OF FREEDOM

Although flexible manipulators own many potential advantages, one of their major disadvantages is the deterioration of the end-effector accuracy due to the flexibility. Therefore, how to reduce vibration is a significant problem. Inspired by the observation on the motion behaviors of animals, a new idea of decreasing motion deflection of the flexible manipulator is suggested. The concept of controllable local degrees of freedom is proposed and analyzed. By way of optimizing local motion provided by the controllable local degrees of freedom, the end-effector deflection of the flexible manipulator can be effectively decreased through dynamic coupling. The corresponding optimal method for vibration control of the flexible manipulator is put forward. The kinematic simulation is carried ant on a three-link flexible manipulator The corresponding results verify the feasibility of this method.     

Plane kinematic calibration method for industrial robot based on dynamic measurement of double ball bar

A new calibration method is proposed to improve the circular plane kinematic accuracy of industrial robot by using dynamic measurement of double ball bar (DBB). The kinematic model of robot is established by the MDH (Modified Denavit-Hartenberg) method. The error mapping relationship between the motion error of end-effector and the kinematic parameter error of each axis is calculated through the Jacobian iterative method. In order to identify the validity of the MDH parameter errors, distance errors and angle errors of each joint axis were simulated by three orders of magnitude respectively. After multiple iterations, the average value of kinematic error modulus of end-effector was reduced to nanometer range. Experiments were conducted on an industrial robot (EPSON C4 A901) in the working space of 180 mm × 490 mm. Due to the measuring radius of DBB, the working space was divided into 30 sub-planes to measure the roundness error before and after compensation. The average roundness error calibrated by the proposed method at multi-planes decreased about 21.4%, from 0.4637 mm to 0.3644 mm, while the standard deviation of roundness error was reduced from 0.0720 mm to 0.0656 mm. In addition, by comparing the results of positioning error measured by the laser interferometer before and after calibration, the range values of motion errors of end-effector were decreasing by 0.1033 mm and 0.0730 mm on the X and Y axes, respectively.     

DYNAMIC MODELLING OF BAR-GEAR MIXED MULTIBODY SYSTEMS USING A SPECIFIC FINITE ELEMENT METHOD

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一种柔性冗余度机器人的动力学优化算法

提出了一种柔性冗余度机器人的动力学优化算法 ,它采用拉格朗日乘子法 ,既根据复模态算法进行动力学优化以实现机器人末端的振动抑制 ,又可同时进行关节驱动力矩的优化。最后通过对三维四自由度柔性机器人的数值仿真 ,初步验证了这一方法的有效性和良好效果     

Error analysis of a parallel mechanism considering link stiffness and joint clearances

In order to utilize a parallel mechanism as a machine tool component, it is important to estimate the errors of its end-effector due to the uncertainties in parts. This study proposes an error analysis for a new parallel device, a cubic parallel mechanism. For the parallel device, we consider two kinds of errors. One is a static error due to link stiffness and the other is a dynamic error due to clearances in the parts. In this study, we propose a stiffness model for the cubic parallel mechanism under the assumption that the link stiffness is a linear function of the link length. Also, from the fact that the errors of u-joints and spherical joints are changed with the direction of force acting on the link, they are regarded as a part of link errors, and then the error model is derived using forward kinematics. Lastly, both the error models are integrated into the total error, which is analyzed with a test example that the platform moves along a circular path. This analysis can be used in predicting the accuracy of other parallel devices.     

Load carrying capacity of flexible joint manipulators with feedback linearization

A computational technique for obtaining the maximum load carrying capacity of robotic manipulators with joint elasticity, subject to accuracy and actuators constraints, is described herein. A feedback linearization technique is used to minimize end-effector deflection. An inversion algorithm is employed for the synthesis of a dynamic feedback control law that provides input-output decoupling and full state linearization. The linearizing input transformations and the corresponding state diffeomorphisms are presented. The proposed technique is then applied to a flexible joint robot. Linearizing control law is been expressed in terms of different sets of model variables and their derivatives. As a result, different tracking errors and torques are introduced in the robot-given trajectory and different load carrying capacities are obtained.