整体式压电三向车削测力仪的研制北大核心CSCD

针对三维动态车削力的测量需求及刀杆式、平台式压电测力仪的不足,研制了一种带有双弹性环结构的整体式压电三向车削测力仪。设计了测力仪的2种结构方案,并对比了2种方案的优劣,阐述了测力仪和压电测试系统的测量原理,对测力仪进行了静态标定实验和动态冲击实验,实验结果表明:测力仪具有优良的静、动态性能,满足了动态车削力的测量需求。     

PCD刀具钻削碳纤维复合材料研究

1 试验设备与方案 为开展碳纤维复合材料钻孔试验,搭建的高速钻削试验系统如图1所示,该试验系统由机床部分和钻削力测量系统组成.钻削力测量系统由钻削测力仪、电荷放大器、A/D信号采集卡和PC机等组成,其中钻削测力仪采用Kistler9271A型测力仪,测力仪标定如图2所示.在钻削试验过程中,测力仪内的压电石英传感器将钻削轴向力转化成相应大小的电荷值,并由电荷放大器和A/D信号采集卡将其转化成数值信号,供计算机进行记录和数据的分析处理.     

面向下肢助力外骨骼的脚底测力系统研究

要实现下肢助力外骨骼机械腿对穿戴者的运动跟随及有效助力,通过检测穿戴者脚底力变化信息进行运动意图识别是非常关键的环节。针对下肢助力外骨骼机器人的控制需求,提出了一种鞋垫式脚底测力系统。进行了脚底测力系统本体设计及传感器信号调理电路的设计,并进行了脚底测力系统的实验研究。设计出的脚底测力系统应用于下肢助力外骨骼机械腿控制中,实验结果表明,脚底测力系统检测出的足底压力变化信息能很好的实现外骨骼机械腿的控制。     

基于PVDF的足底测力系统研究

为实现人体不同路况运动过程中的步态识别,研制出一种便于穿戴的鞋垫式足底测力系统。以PVDF压电薄膜为传感材料,设计足底传感器。采用由电荷放大电路、滤波电路及电压放大电路组成的信号系统对传感器输出信号进行采样及处理,进行了电荷放大电路中的反馈电阻与反馈电容的实验测试选型分析研究。进行了平地行走、楼梯行走及斜坡行走的实验,实验表明,该足底测力系统具有良好的灵敏度与测量精度,并且采用PVDF内嵌在鞋垫的结构,使得测力系统适用于不同模式行走运动的检测。     

振动摆辗的体积效应实验研究

根据振动摆辗机的工作原理,设计了一套基于AT89C51单片机的振动摆辗力检测系统.系统选择了合适的测力传感器,设计了信号调理电路,利用单片机采集摆辗力数据,并通过串口将数据传送到PC右口连行分析处理,为振动摆动辗压技术下金属成形的体积效应研究提供了一种简单可行的实验方法.     

基于传感器增强的测力仪实验平台扩展方法

针对现有测力平台无法满足大尺寸特征实验、微细切削实验以及缺乏多信号融合等问题,提出了基于传感器增强的测力仪实验平台扩展方法。以Kistler 9257B压电测力仪为基础,对测力平台进行扩展。通过增加大尺寸测力板满足大尺寸特征的切削实验要求。同时增加加速度传感器,通过测量加工过程中工件的加速度,对切削力进行惯性力补偿,提高切削力的测量精度,并可用于微细切削实验。此外通过将声发射传感器监测加工过程中的声发射信号同切削力和振动信号融合,为加工过程中刀具状态的辨识提供依据。验证表明,经过扩展的测力平台可以达到预期的效果。     

基于C8051F020的踏跳力动态测量系统

介绍了一种利用C8051F020单片机设计的踏跳力动态测量系统.根据系统功能的要求,给出了系统的整体原理框图.通过对测力传感器感受被测力瞬间动态特性的分析,提出了在测力传感器的设计中应该注意的一些要点.并在硬件设计部分介绍了信号调理、放大滤波电路和串行通讯电平转换电路的设计与实现.最后给出了系统的主控制程序流程图.     

基于Stewart机构的六维力/力矩传感器

基于Stewart机构的六维力/力矩传感器是一种十分优越的测力传感器,具有测力接触面大、承载能力强、量程大、测力信息丰富等优点,可被广泛应用在航空机器人、航空航天技术及宇宙空间器的对接试验、风洞试验等场合。根据以上特点,阐述Stewart机构的六维力/力矩传感器的测力原理,分析传感器的受力变形,零部件设计尺寸和理论尺寸的制造误差及安装误差对其测力精度的影响,并对其结构参数进行优化设计。提出一种标定方法,研究其标定算法。对自主研制的Stewart六维力/力矩传感器进行标定试验,得出该传感器的标定矩阵。研究结果表明,用标定矩阵代替传感器理论影响系数矩阵参与6个单向力传感器输出信号的耦合,能够有效地提高该传感器的测力精度。     

附着式测力传感器在大型轧机轧制力监测中的应用

介绍了附着式测力传感器的结构、原理及实际应用,并从实用性、经济性及可操作性的角度对其进行了阐述.最后又结合轧机工况监测系统,使用附着式测力传感器对轧制力进行在线监测,证明具有较好的使用效果.     

铣削加工测力刀柄参数优化设计研究

为适应高精密加工对切削力的监测需求,文中面向铣削加工设计了一种无线测力刀柄,使用压电薄膜和弹性检测梁采集力信号。为提高检测信号的灵敏度,基于COMSOL Multiphysics软件使用Nelder-Mead算法对刀柄的结构参数进行优化设计,并通过有限元仿真对优化结构进行刀柄结构刚度校核和动态特性分析,最后进行铣削对比实验,验证设计方案的可行性。结果表明,文中设计和优化的测力刀柄具有良好的灵敏度,刀柄的动静态特性满足使用需求,是一种有效的切削力监测方案。     

Development of a force controlled nanocutting system using a flexible mechanism for adaptive cutting of microstructures on non-planar surfaces

A force controlled nanocutting system based on a flexible mechanism was developed. Instead of utilizing force sensors, the force sensing and control in the developed system is realized by sensing and controlling the deformation of the flexible mechanism. With force feedback control for controlling the cutting force in real time, this system could achieve adaptive cutting along non-planar surfaces without prior knowledge about the surface shape. The finite element method was used to model the flexible mechanism and a Pareto-based multi-objective optimization algorithm with the goals of high force resolution and stability was used to obtain the geometric parameters of the flexible mechanism. During the cutting processing, a capacitive displacement sensor was used to detect the deformation of the flexible mechanism to measure the force in real time, and a piezoelectric ceramic actuator was used to adjust the feed position of the tool to control the cutting force. Nanocutting experiments of microstructures were successfully carried out on inclined and curved surfaces of ductile as well as brittle materials without prior knowledge of their surface forms.     

汽车制动器外壳液压深拉成形的数值模拟

液压成形能显著降低成本和提高制件质量,在汽车制造领域中将广泛采用。文中用Dynaform有限元仿真软件对汽车制动器外壳液压深拉成形过程进行了模拟,分析了压边力、液体压力、毛坯形状、压边间间隙对制动器外壳件成形质量的影响。研究结果表明,合适的压边力、液体压力、毛坯形状、压边间间隙能控制制动器外壳件拉深缺陷的发生,可获得好的壁厚分布,能实现一次成形成功的成形区域,为今后此类型的制动器外壳件液压成形生产提供了技术指导。     

Novel Door-opening Method for Six-legged Robots Based on Only Force Sensing

Current door-opening methods are mainly developed on tracked, wheeled and biped robots by applying multi-DOF manipulators and vision systems. However, door-opening methods for six-legged robots are seldom studied, especially using 0-DOF tools to operate and only force sensing to detect. A novel door-opening method for six-legged robots is developed and implemented to the six-parallel-legged robot. The kinematic model of the six-parallel-legged robot is established and the model of measuring the positional relationship between the robot and the door is proposed. The measurement model is completely based on only force sensing. The real-time trajectory planning method and the control strategy are designed. The trajectory planning method allows the maximum angle between the sagittal axis of the robot body and the normal line of the door plane to be 45º. A 0-DOF tool mounted to the robot body is applied to operate. By integrating with the body, the tool has 6 DOFs and enough workspace to operate. The loose grasp achieved by the tool helps release the inner force in the tool. Experiments are carried out to validate the method. The results show that the method is effective and robust in opening doors wider than 1 m. This paper proposes a novel door-opening method for six-legged robots, which notably uses a 0-DOF tool and only force sensing to detect and open the door.     

混合压边液体内向流动动态充液拉深

为抑制液体内向流动动态充液拉深中凸缘增厚而造成的拉深阻力急剧增长,提出混合压边液体内向流动动态充液拉深新方法。对定间隙下设定恒定压边力的混合压边充液拉深压边形式实质进行分析,采用有限元研究混合压边方式下压边间隙、压边力以及径向压力的变化对成形过程的影响。研究结果表明:定间隙下设定恒定压边力的混合压边充液拉深压边形式的实质是设定压边间隙和设定压边力压边方式的混合;采用混合压边方式可以降低实际最大压边力,降低凸缘区的摩擦阻力,减少第二个谷底点的减薄率;压边力影响零件直壁部分壁厚分布,较大的压边力得到的零件直壁壁厚较薄;压边间隙的变化影响成形零件直壁壁厚分布,较小的压边间隙成形零件直壁较薄,第二个谷底点越接近零件底部。     

CUTTING PROCESS DIAGNOSTICS UTILISING A SMART CUTTING TOOL

A new sensorised boring tool has been developed to enhance the flexibility and precision of line boring processes. A position sensor and tool tip actuator to control and its controller electronics were integrated into a cutting tool. To take further advantage of this highly sophisticated tool, a process diagnostic method based on cutting force measurement method was developed. An observer implemented in the tool controller estimates the disturbance to the actuator using the tool position sensing information. The estimated disturbance is the same as cutting force applied to the tool tip. The algorithm utilising the cutting force to detect cutting process faults, such as tool tip breakage and misalignment of workpiece has been designed and tested experimentally.     

机器人辅助腹腔镜手术中力感知技术的研究进展

为了推动机器人辅助腹腔镜手术中力感知技术的深入研究和临床应用,综述了其研究进展。针对有传感器的力感知,将其分为基于电信号和基于光信号两类,分析了传感器在手术器械上的位置分布、机械结构、测量范围、测量精度和电磁兼容性等关键指标,并讨论了其优势和局限;针对无传感器的力感知,将其分为基于视觉和基于动力学模型两类,并分析了其实现方法、技术障碍和误差来源。最后,展望了机器人辅助腹腔镜手术中力感知技术的发展趋势。     

Development of a microlateral force sensor and its evaluation using lateral force microscopy

A microlateral force sensor (MLFS) was developed and evaluated using atomic force microscopy (AFM). The sensor was attached to a sensing table supported by a suspension system. The lateral motion of the sensing table was activated by a comb actuator. The driving voltage to the comb actuator was controlled to maintain a constant position of the sensing table by detecting the tunneling current at a detector, which consisted of two electrodes where the bias voltage was applied. An AFM was used to apply a lateral force to the sensing table of the sensor. When the probe of a cantilever was pressed against the sensing table and a raster scanning was conducted, the driving voltage of the comb actuator changed to compensate the friction force between the probe and sensing table. AFM measurements of an asperity array on the sensing table were conducted, and a lateral force microscopy image (LFM) was obtained from the change in driving voltage. The image by MLFS was very similar to the LFM image that was conventionally obtained from torsion of the cantilever. The LFM image strongly correlated with the gradient image calculated from the AFM topographic image. The force sensitivity of the MLFS was determined by comparing the LFM image obtained by using the MLFS with the tangential force derived from the gradient of the AFM image.     

基于约束矩阵与蚁群算法的CAPP加工工序优化排序

针对复杂零件工艺方案全局优化难题,提出基于约束矩阵与蚁群算法进行工序优化的方法。约束矩阵包括客观约束矩阵与费用约束矩阵,在分析两个矩阵的基础上,将客观约束矩阵与费用约束矩阵统一为一个矩阵,在此矩阵约束下,用蚁群算法进行工序排序优化,从而保证快速地得到正确的优化工艺序列。结果表明,所提方法具有良好的实用效果。     

基于正交试验的半球形拉深成形工艺参数优化

以某半球形TA1钛合金拉深成形件为例,通过ABAQUS有限元软件建立了拉深成形三位模型和数值模拟正交试验方案。以是否破裂和起皱为衡量指标,探究凹凸模间隙、拉深速度和压边力对拉深成形件质量的影响,结果表明:起皱现象主要出现在压边区域不影响成形件质量,对底部最小厚度的影响从大到小依次为拉深速度、压边力以及凹凸模间隙。基于正交试验结果设计优化方案,得到最优工艺参数组合并将其应用于实际生产得到表面质量较好的拉深成形件,结果表明:基于正交试验对拉深成形工艺参数优化的方案可行,可以为企业生产提供指导,具有一定的工程应用价值。     

Direct measurement of tapping force with a cantilever deflection force sensor

An experimental set up dedicated to the measurement of atomic force microscope tapping force was developed. In the set-up, a standard TappingMode™ probe cantilever was used to tap another cantilever equipped with its own low noise and high sensitivity deflection detection system for force measurement. The amplitude and phase change of the tapping lever as well as the deflection of the sensing lever were simultaneously recorded as a function of tip/surface separation. Since the deflection of the sensing cantilever reflects the average force over one interaction cycle, we measured the total average force quantitatively after calibrating the spring constant and deflection sensitivity of the sensing lever. Considerable effort was made to achieve the same force curve in the tapping force measurement as occur during imaging of conventional samples such that the detected tapping force reflects the same interaction of the imaging process.