模块化变形机器人非同构构形表达与计数

提出一种新型链式可重构模块机器人平台,该机器人平台具有手动可重构和自动变形的特点,介绍一种三模块变形机器人样机。组成机器人的单个模块可以简化为由模块本体、连接臂和偏置关节组成。模块的数量可以根据实际工作的需要进行选择,模块间的连接具有规则连接和非规则连接两种方式;同时,由连接模块的偏置关节的运动,模块间的相对位置可以改变。由于模块连接方式的不同和模块间相对位置的变化,变形机器人具有多种非同构构形;为此,根据模块的物理结构和邻接关系提出了用构形矩阵来表达机器人结构的拓扑信息,并在仿真环境下进行等效描述;提出基于组合计数原理的递归算法,用于多模块变形机器人的非同构构形的计数,并根据构形矩阵的拓扑信息对构形进行评价。最后根据仿真结果给出了一种三模块变形机器人样机对称构形的设计示例,验证了算法的可行性。     

一种可重构模块化机器人的设计与运动学分析

设计了一种结构简单、联接方便的模块化机器人关节结构,每个模块具有统一的机械接口和电路接口,实现了接口的通用化,可以根据实际工作需求自由选择关节模块数目进行机器人的结构搭建,实现在不同工况下,满足相应的机器人所需要的自由度。用旋量理论对该模块组合的六自由度机器人进行运动学求解和工作空间分析,充分证明了模块化关节结构设计的可行性与有效性。     

基于任务的可重构模块机器人构形确定方法

可重构机器人为柔性加工系统提供了更多的选择,但复杂多变的任务、环境以及机器人模块无穷组合,为机器人构形的确定带来了很大的难题。采用遗传算法和迭代算法分两级搜索对机器人构形组合进行优化设计:运用遗传算法对机器人构形进行进化设计,满足工作空间的可达性、环境避障、线性和角度误差、末端操作灵巧度、运动关节的动力学要求、期望模块数目等性能指标要求。运用迭代算法对构形进行运动学逆解求解,计算空间工作点的可达性适应度。根据可装配的模块机器人及模块化思想,建立各个模块的速度、加速度等动力学表达式及相关修正公式,采用补偿迭代法来自动生成动力学方程,计算运动模块驱动性能的适应度。用专家经验对搜索得到适应度较高的构形进行修正,得到满足工作要求的机器人构形。最后给出实例验证。     

可重构机器人设计理论与研究

可重构机器人系统主要是由标准模块构成,模块和模块之间通过接口进行互联和通信,根据不同的实际需求,各个模块可以实现快速组合成不同的构形,故可以实现可重构,可以很好的满足工业化发展的现状,节约成本,高产高效,有效的提升企业的竞争力。本文对可重构机器人的设计理论进行了相关研究和讨论,从构形设计理论出发,以构形设计问题为主要对象,覆盖了涉及的各方面重要内容,构建了模型,对系统进行了优化设计,证明了构形设计方法的正确性和有效性。     

基于Adams和Matlab的机器人手臂运动控制联合仿真研究

为了提高机器人手臂设计的效率,缩短研发周期,首先在三维设计软件Solidworks中设计出六自由度串联机械手臂的三维模型,再将该模型导入到运动学和动力学分析软件Adams中进行运动学分析,验证虚拟样机模型约束的正确性。该虚拟样机通过Adams/Controls接口模块将虚拟样机导入Matlab软件,通过Matlab/Simulink模块搭建控制系统,导入的虚拟样机作为联合仿真控制系统的机械系统部分。采用基于计算力矩法的系统控制律动态控制关节的力矩,仿真结果显示,机器人手臂关节具有良好的动态响应和准确的轨迹跟踪能力,为实物样机的设计开发提供了有效的参考。     

可重构模块化机器人逆运动学建模

可重构模块化机器人的构形确定后,找出依序的关节模块、连杆模块.采用局部指数乘积公式和微分运动学公式建立逆运动学数学模型,然后采用牛顿-拉普松迭代法获得数值逆运动学的迭代公式;用Matlab语言建立了逆运动学的用户界面,自动生成逆解说明该方法的可行性.     

冗余度机器人多关节故障的运动学容错性及其优化

首先基于对冗余度机器人故障构形的操作灵巧性分析,推导出机器人各阶子构形可操作度之间的关系。其次,分析了多关节故障构形下的相对操作灵巧性,并进一步由子构形的可操作度及对应的相对可操作度出发,提出了适用于多关节故障的运动学容错性优化目标。这种算法具有计算量小、可在线实时运算并保证关节速度连续的特点,所提优化目标适用于一个或多个关节故障。算例显示了算法的有效性。     

可重构机器人模块间装配误差识别方法研究

基于对可重构机器人配对接口间位姿误差的分析划分,研制模块间装配误差在线测量识别接口,建立配对接口位姿误差与接口几何结构偏差之间的关系模型,进而建立配对接口位姿误差与配对接口内部测距传感器测量值之间的映射关系模型,提出一种基于内部测距传感器位移量的模块间装配误差在线识别、补偿方法.为验证方法的正确性,研制单关节?连杆试验平台.试验结果表明装配误差经在线识别、补偿后,连杆末端的位置误差平均值减少7倍多.     

基于双四杆机构的蟑螂机器人设计与分析

针对蟑螂机器人直接串联式腿构形承载能力差、机体刚度不能满足要求,以及单腿少于3自由度构形不能精确控伟体位姿的问题,设计一种基于双四杆机构的仿生蟑螂机器人.对机器人求运动学逆解,求得各个驱动关节转角;对机器人行静力学分析,通过解析法得到关节驱动电动机所需的驱动转矩;用可视化的方法对机构的工作空间进行分析,同时提出速工作空间与越障工作空间的概念来衡量机器人的平面运动性能与越障性能;制作样机进行行走试验.通过与直接串联构的比较可知,新设计的样机不仅提高了移动速度,同时增加了系统承载能力,验证了上述设计的合理性与可行性.     

绳驱动连续体机器人标定方法

为提高绳驱动连续体机器人的定位精度,提出了一种针对此类机器人的误差标定与补偿方法.该方法利用指数积(POE)公式建立连续体机器人关节模块的运动学模型,并利用运动学模型推导出误差传递模型.针对误差模型采用最小二乘方法进行误差的辨识,将辨识后的误差补偿至机器人的运动学模型,从而提高机器人关节模块的模型精度.制作了基于柔性支...     

超声波在机械研磨加工中的应用与研究

为了提高机械研磨的材料去除率,探讨了在机械研磨的界面上引入超声能的复合研磨方式,将机械研磨和引入超声的复合研磨两种方法的去除效率进行了实验对比;发现复合研磨后,去除效率有显著提高;得出超声/机械复合研磨的加工效率明显优于机械研磨。所获得的工艺规律对于工业生产具有一定指导意义。     

基于微环谐振器的溶液浓度传感器研究

设计了基于微环谐振器的溶液浓度传感器,提出了一种溶液浓度测量的新方法。介绍了全通微环谐振器(MRR)的结构及传输机制和MRR浓度传感器的工作原理。根据电磁场理论得到了狭缝波导的特征方程,计算了MRR的共振波长,并以乙二醇溶液为例,利用有限时域差分法模拟了外界环境浓度变化时微环的功率谱。模拟结果表明:随着乙二醇溶液浓度增大,MRR的谐振波长与乙二醇溶液浓度的变化近似呈线性关系,与理论计算结果一致;并对该传感器的灵敏度进行计算,结果显示灵敏度可达490.2nm/RIU。采用MRR测量液体浓度成本低、结构简单,能够实现对环境介质的快速精确测量。所设计传感器还可用于测量固体、气体浓度和其它与浓度、折射率相关的参量。     

超声/机械复合研磨在光纤连接器端面加工中的应用研究

探讨了在机械研磨的界面上引入超声能的复合研磨方式，将机械研磨和超声／机械研磨两种方法的去除效率、研磨质量进行了实验对比，发现超声／机械复合研磨的效率和质量都有显著提高，可以达到插入损耗小于0．1dB、回波损耗小于-60dB的性能指标；对超声／机械复合研磨的机理进行了初步分析。获得的规律对工艺研究及工业生产有指导意义。     

Finite element prediction of material removal rate due to traveling wire electrochemical spark machining

Manufacturing engineers are facing new challenges during machining of electrically nonconducting or partially conducting materials such as glass, quartz, ceramics, and composites. Traveling wire electrochemical spark machining (TW-ECSM), a largely unknown technology, has been applied successfully for cutting these types of materials. However, hardly any theoretical work has been reported related to machining performance of TW-ECSM process. The present work is an attempt in this direction. In the present work, a 3-D finite element transient thermal model has been developed to estimate the temperature field and material removal rate (MRR) due to Gaussian distributed input heat flux of a spark during TW-ECSM. First, the developed code calculates the temperature field in the workpiece and then MRR is calculated using this temperature field. The calculated MRR has been compared with the experimental MRR for verifying the approach. Computational experiments have been performed for the determination of energy partition and spark radius of a single spark. The effects of various process parameters such as energy partition, duty factor, spark radius, and ejection efficiency on MRR have been reported. It has been found that MRR increases with increase in energy partition, duty factor, and ejection efficiency but decreases with increase in spark radius.     

MRR 故障对二进制全光全加器的性能影响研究

针对现有的二进制全光全加器所需微环谐振器(MRR)数量较多的问题,首次提出了3个MRR串联结构的全光全加器。针对MRR对温度的波动和制程偏差非常敏感,容易产生故障,建立了MRR故障模型,设计了全光全加器(OFA)的可靠性指标平均误差距离,分析了MRR单故障模型对OFA性能的影响。插入损耗(insertion loss, IL)的实验结果表明,提出的OFA结构总体上优于现有的OFA结构;相比现有的方案,提出的OFA结构的MRR硬件开销最多减少70%,最少减少50%;平均误差距离的实验结果表明,方案1和方案2的平均误差距离较大,本文提出方案的平均误差距离适中;多位二进制全加器中,最高位在单故障模型下的,平均误差距离的绝对值均随着多位二进制全加器的位数增加而增大;最低位在单故障模型下的,平均误差距离的绝对值均随着多位二进制全加器的位数增加保持不变;实物验证和基于Modelsim平台的实验验证了MRR故障对全加器的性能影响的正确性。     

Research on electrochemical discharge-assisted diamond wire cutting of insulating ceramics

Insulating ceramics are difficult to cut because of their high hardness and brittleness properties. This research proposes an electrochemical discharge-assisted diamond wire method for cutting insulating ceramics. The high temperature generated from electrochemical discharge facilitates the spalling of ceramics by the moving diamond wire. Experimental results showed that the material removal rate (MRR) of the new cutting method increased compared with the conventional diamond wire cutting process. Besides, electrochemical discharge had limited influence on the surface roughness and the wear of diamond wire. Additionally, the influence of the process parameters (DC voltage, wire speed, and counterweight mass) on the MRR and surface roughness was analyzed through experiments. The results showed that the MRR and surface roughness initially increased and then decreased with the increasing DC voltage; however, the variation was little. The higher wire speed resulted in an increased MRR and had little influence on the surface roughness. The MRR and surface roughness increased with the increasing counterweight mass.     

Comparison between four piezoelectric energy harvesting circuits

This paper investigates and compares the efficiencies of four different interfaces for vibration-based energy harvesting systems. Among those four circuits, two circuits adopt the synchronous switching technique, in which the circuit is switched synchronously with the vibration. In this study, a simple source-less trigger circuit used to control the synchronized switch is proposed and two interface circuits of energy harvesting systems are designed based on the trigger circuit. To validate the effectiveness of the proposed circuits, an experimental system was established and the power harvested by those circuits from a vibration beam was measured. Experimental results show that the two new circuits can increase the harvested power by factors 2.6 and 7, respectively, without consuming extra power in the circuits.     

Self-dressing effect using a fixed abrasive platen for single-sided lapping of sapphire substrate

Single-sided lapping is crucial in sapphire wafering processes for improving flatness and achieving the target wafer thickness using loose abrasives. In single-sided lapping process, the Material removal rate (MRR) is a key factor for reducing process time and cost. However, the MRR is limited when using loose abrasives because abrasives mostly act by rolling and sliding. Many researchers have studied fixed abrasives to increase the MRR, but the MRR decreases with time. To solve this problem, the self-dressing effect was studied with various pressures, velocities, cutting fluids and wafers. The MRR decreased due to the wear of abrasives, and the pressure and velocity have little effect on the self-dressing. Lapping experiments were done using cutting fluid with a lapped wafer and sawed wafer. The MRR, plate roughness and thickness were measured to study the wear of the abrasive and the self-dressing effect. The cutting fluid delayed the wear of the abrasives and thus improved the decrease in MRR, but it had little effect on the self-dressing effect, like in the case when water was used. When using cutting fluid and a sawed wafer, the MRR was high and did not decrease. A concentrated load on the plate caused by shape error and saw marks on the sawed wafer could produce the self-dressing effect. We verified that a sawed wafer could produce the self-dressing effect on even a worn plate.     

Optimal parameter settings for rough and finish machining of die steels in powder-mixed EDM

The present study was undertaken to identify the appropriate parameter settings for rough and finish machined surface for EN31, H11, and high carbon high chromium (HCHCr) die steel materials in a powder-mixed electric discharge machining process. The effect of seven different process variables along with some of their interactions was evaluated using a dummy-treated experimental design and analysis of variance. Material removal rate (MRR), tool wear rate, and surface finish were measured after each trial and analyzed. The parameter settings for rough and finished machining operations were obtained. EN31 exhibited maximum MRR as compared to the other two materials at similar process settings. Copper (Cu) electrode with aluminum suspended in the dielectric maximized the MRR. Suspending powder in the dielectric resulted in surface modification. Graphite powder showed a lower MRR but improved the surface finish. HCHCr require higher current and pulse on settings for initiating a machining cut and works best in combination with tungsten–Cu electrode and graphite powder for improved finish. The MRR for H11 is lower than EN31 but significantly higher than HCHCr under same process conditions.     

Feasibility study of micro-slit EDM machining using pure water

This study addresses micro-slit EDM machining feasibility using pure water as the dielectric fluid. Experimental results revealed that pure water could be used as a dielectric fluid and adopting negative polarity EDM machining could obtain high material removal rate (MRR), low electrode wear, small slit expansion, and little machined burr, compared to positive polarity machining. In comparing kerosene versus pure water, pure water was observed to cause low carbon adherence to the electrode surface. Also discharge energy does not decrease and the discharge processes are not interrupted. Therefore, MRR was higher, and related electrode wear ratio compared to kerosene use was lower. In a continual EDM with multi-slit machining, kerosene will cause carbon element adherence, creating an initially high MRR and electrode wear, with rapid decline. However, pure water will not cause carbon element adherence on the electrode surface, so MRR and electrode wear is always stable in this process.