Research on the Residual Error Evaluation Method for Deterministic Polishing of Aspheric Optics

研究非球面光学元件确定性抛光中表面残余误差的评价方法。对两种非球面残余误差的评价方法,分别为轴向误差法和法向误差法,进行理论研究。指出非球面的残余误差理论上应使用法向误差法来评价,并提出一种基于轴向残余误差求解法向残余误差的方法,继而对二者进行比较发现两者存在一定的偏差,并且差值从非球面的中心向边缘方向逐渐增大。以气囊抛光和数控小磨头抛光为例,通过试验表明使用轴向误差法评价残余误差,进行确定性抛光引入了不同程度的加工误差,引入的加工误差的大小与非球面光学元件的口径和顶点曲率半径的比值(即“相对孔径“)成正相关,故对于相对孔径较小的非球面光学元件在确定性抛光中可使用轴向误差法替代法向误差法作为残余误差的评价方法,反之,则应使用法向误差法。Residual error evaluation method for deterministic polishing of aspheric optics is studied.Two residual error evaluation methods, which are axis-direction error method and normal error method respectively, are researched theoretically.It's inferred that the residual error of aspheric surface should be evaluated by normal error method.A new approach is proposed to calculate normal direction residual error on the basis of the axis-direction residual error of the aspheric surface.There exists difference between these two kinds of error which increases from the center of the aspheric optic to the edge through the comparison of them.Taking bonnet polishing and numerical controlled small tool polishing as examples, experiments are made to quantitatively prove that using axis-direction error method to evaluate residual error in deterministic polishing would introduce different degrees of processing error.It's found that the processing error is positively correlated with the relative aperture of aspheric optics, which is the ratio of the optic's aperture and vertex's curvature radius.Therefore, it is recommended to use axis-direction error method instead of normal error method as the evaluation method of the residual error during deterministic polishing aspheric optics with relatively small relative aperture; the opposite is the other way around.国家科技重大专项资助项目(2013ZX04006011-206

Dynamic Removal Function Modeling of Bonnet Tool Polishing on Optics Elements

目前对于光学元件气囊抛光系统驻留时间的求解都是基于静态的去除函数,然而实际抛光过程中,抛光头不断地移动,故对于动态去除函数的研究显得尤为必要。通过有限元仿真分析的方法得到动静态接触区的轮廓和接触应力分布数据,发现对于平面工件,动静态接触区均为圆形,而且大小基本一致,且动态接触区应力分布与静态接触区应力分布相比,其峰值点沿抛光头移动的相反方向偏移。在此基础上,根据静态接触区应力呈类高斯分布的理论,利用最小二乘拟合的方法,推导出动态接触区的应力分布函数。通过搭建动静态接触区轮廓提取装置,设计不同下压量下动静态接触区的轮廓提取试验,验证有限元仿真结果的准确性。基于仿真和试验结果推导出动态去除函数,对其进行数值仿真,并与静态去除函数进行对比,发现前者去除率偏小,而且最低点也发生偏移。The dwell time function of the bonnet tool polishing on optics elements is achieved based on static removal function in recent studies.But the polishing tool keeps moving during the process,it's necessary to do the research on dynamic removal function.The static and dynamic contact zone is acquired through finite element simulation analysis,and so is the contact pressure.Both of the contact zones are circle and the size of them are almost the same.The peak point of the dynamic contact pressure has an offset contrary to the direction of the tool movement compared to the static contact pressure.The dynamic contact pressure distribution function is deduced by using the least square method based on the theory that the static pressure distribution function is a modified Gaussian function.The device which can extract both the dynamic and static contact zone is set up to capture them on the condition of different offset.Then the simulation results are verified.The dynamic removal function is deduced and numerical simulated based on the forward simulation and experiment results.The removal rate of the dynamic removal function is smaller than the static removal function and its nadir has a deflection compared to the latter.国家自然科学基金(51075343); 厦门市科技计划(3502Z20113007)资助项

Volumetric Error Modeling and Compensation of Precision Measuring Platform Based on Multi-system Theory

针对大口径光学元件精密检测平台的工作特点及影响其空间误差的各项几何误差因素,运用多体系统理论,用低序体阵列描述多体系统拓扑结构,建立一种空间误差数学模型。综合应用激光干涉仪、球杆仪和激光位移传感器等仪器设备,提出大口径光学元件精密检测平台各项几何误差和空间误差的测量方法,并对模型中所涉及的各项几何误差进行了系统分析和全面测量,对空间误差进行补偿。误差补偿实验证明所提模型正确有效,将空间误差从补偿前-70.01~22.14μM降低到补偿后-4.22~5.8μM,大大提高了精密检测平台的测量精度。A volumetric error model is proposed according to the working characteristics and the geometric errors of a large-size optical element precision measuring platform.The volumetric error model is based on multi-system theory,and the topological structures of the multi-system theory are described by the number arrays of low-order body.To testify the volumetric error model,a new combined measurement experiment by the application of laser interferometer,double-ball bar,laser displacement sensor and other relative instruments is conducted for measuring the geometric and volumetric errors of the measuring platform before and after error compensation.The error compensation experiments show that the volumetric error is reduced from -70.01 ~ 22.14 μm to -4.22 ~ 5.8 μm,which also reflects the validity of the volumetric error model.国家自然科学基金项目(51075343); 福建省自然科学基金项目(2012J05098

Control Techniques of Bonnet Polishing for Free-form Optical Lenses with Precession

针对自由曲面光学元件的加工特点,研究气囊抛光自由曲面光学元件进动运动控制技术,用于求出气囊工具进动过程中两虚拟轴的转角,实现对气囊自转轴空间位置的控制。以气囊自转轴为研究对象,由于自由曲面光学元件上每个点的法线三维坐标都不相同且气囊进动抛光过程中气囊自转轴与工件加工点局部法线夹角不变,提出建立基坐标系和抛光点对应三维空间坐标系的方法,得到抛光过程中气囊自转轴的空间位置变化情况,而后利用旋转坐标变换得到气囊抛光进动运动控制模型;在所建立的自由曲面光学元件气囊抛光进动运动控制模型中加入控制算法,求出抛光自由曲面光学元件各点时气囊工具两个虚拟旋转轴的转角。利用MATlAb对自由曲面光学元件不同方向截面进行仿真抛光试验,得到自由曲面各方向上气囊抛光进动运动曲线以及仿真进动角曲线,结果证明了自由曲面光学元件气囊抛光进动运动控制模型及控制算法的正确性。Control techniques of bonnet polishing free-form optical lenses with 'precession' is studied,according to the processing characters of free-form optical lenses,to figure out the rotating angles of two virtual axes of bonnet tool,which lead to the controllability of spin axis of bonnet tool.The spin axis of bonnet tool is taken as the object,due to the difference of the local normal of each polishing point and the angle between the spin axis of bonnet tool and local normal is keeping constant in polishing process,a method about how to set up basic coordinate and corresponding coordinate of polishing point is proposed,aiming to get the positions of spin axis of bonnet tool in polishing process,by which a movement model can be obtained by combining with rotating coordinate transformation;Then control algorithm is added to the movement model,and rotating angles of two virtual axes of bonnet tool when polishing each point on free-form optical lenses are calculated.At the end,simulations in polishing different directions of free-form optical lens in Matlab are carried out,to get the curves of precession control and the simulated precession angles,the results reveal that the movement model and control algorithm presented are both correct.国家自然科学基金(51075343); 厦门市科技计划(3502Z20113007)资助项

基于改进RRT算法在ROS中的机械臂避障运动规划研究

针对基于目标偏向的RRT算法在复杂环境下易陷入局部搜索与搜索效率低的不足，在ROS中分别基于Dobot模型和DIY模型，对算法做出进一步的改进。在创建机械臂模型基础上，利用MoveIt!对其进行配置，并通过简化模型来提高碰撞检测效率；在基于目标偏向RRT算法的基础上，分别引入扩展目标变更策略和可变步长对算法进行改进；在ROS中分别进行了不同形态障碍物环境下的避障运动规划仿真；在样机上进行了避障和避障抓取实验。仿真及实验结果表明，提出的改进RRT算法相比基于目标偏向的RRT算法，规划成功率和效率分别可提高42.9%和29.2%

HIRFL-CSR嵌入式数据库的设计实现

本文论述了用于兰州重离子加速器冷却储存环(HIRFL-CSR)控制系统的嵌入式数据库的设计和实现方法。控制系统采用三级数据库实现集中管理、分布式控制。前两级基于Windows平台,采用Oracle数据库通过ODBC进行互联,第三级根据控制系统的需要,采用基于嵌入式Linux平台的SQLite数据库引擎通过高速互联网与前两级交换数据。中控室预先将波形数据、事例表等分散存储到前端嵌入式数据库中,实验时,再由嵌入式数据库将数据传递给波形发生器DSP。在同步触发的控制下,DSP根据得到的波形数据产生所需的控制波形,进而控制电源、控制磁场,达到实验目的

基于P2P技术的CSRe冷却装置控制系统设计；Design of Control System for CSRe Cooling Equipment Based on P2P Technology

HIRFL-CSR工程对CSRe冷却装置电子冷却部分的控制系统在实时性和可靠性方面提出了非常高的要求。电子冷却工作环境复杂,各种干扰难以预测。从电子冷却的控制系统改进出发,以实现电子冷却的自动调束为目标,以高端FPGA和ARM嵌入式系统为基础,采用P2P通讯技术和神经元网络算法来实现对电子冷却的自动控制。该控制系统对电子冷却控制的完善提供了先进的硬件平台和软件实现方案

Research on Applied Digital Medicine to Precision Orthopaedic Surgery

现代骨科医学与计算机科学的融合促进了数字骨科医学的发展.通过厦门大学计算机系生物医学实验室在数字骨科医学领域取得成功的3个典型案例,验证了数字骨科医学应用计算机三维图像处理技术和多种数字图像处理方法,可以直观地显示病人病变部位的骨骼形态,并且在术前设计手术方案,可以预测术后效果,精准度优于传统医学方法.The integration of modern orthopedic medicine and computer science promote the development of digital orthopedic medicine.Digital orthopedic medicine applies three-dimensional image processing technology and a variety of digital image processing to display the pathological changes position of patient′s bone.Preoperative surgical planning and predict the postoperative results can be designed with this technology,which is more accurate than traditional surgical methods.This paper presents three typical surgery cases of digital orthopedic medicine completed by our laboratory.国家自然科学基金项目(30770561;61271336); 卫生部科学研究基金-福建省卫生教育联合攻关Ⅱ期计划项目(WKJ2008-2-41

Controllability of stiffness of bonnet tool polishing large aspheric lenses

为保证气囊抛光过程中抛光运动的高稳定性和均匀材料去除率,对气囊抛光非球面过程中气囊工具刚度的可控性进行了研究。通过分析气囊抛光大口径光学元件时工具的受力情况,计算了气囊工具的刚度,并分析了气囊抛光工具刚度对抛光时材料去除的影响及气囊工具刚度的影响因素。设计了气囊工具刚度控制算法并进行模拟试验,仿真结果表明,在刚度标准值根据加工要求设定以后,即可通过调节工件对气囊工具的反作用力,使得气囊抛光大口径光学元件过程中气囊工具刚度可控。The controllability of stiffness of bonnet tool polishing large aspheric lenses was studied,aiming to ensure the high stability and uniform removal rate of bonnet tool in polishing process.After analyzing the force situation of bonnet tool when polishing large aspheric lenses,the stiffness of the bonnet tool was calculated,and then influencing factors of stiffness of bonnet tool and the effects brought by stiffness of bonnet in polishing process were discussed.After that,control algorithm of bonnet tool was designed and simulated experiments were carried out,the results revealed that the controllability of stiffness of bonnet tool in polishing process could be achieved,which verified the correctness of the control algorithm.国家自然科学基金项目(51075343); 厦门市科技计划项目(3502Z20113007); 厦门大学研究生基础创新科研基金项目(201212G011