复合式MEMS微夹持器的研制

为实现对亚毫米微小构件稳定夹取及可靠释放等操作,研制了一种复合式微夹持器.采用有限元软件分析了微夹持器的机构及动力特性.应用MEMS体硅工艺将静电梳齿驱动与气动吸放集成构成复合式驱动,气动吸放的引入改善了微夹持器的操作性能,S形柔性梁结构的设计将梳齿驱动的直线运动转化成末端夹爪的转动实现了夹持操作.两种不同尺寸的微夹持器,有效扩展了微夹持器的夹持范围.根据微夹持器的操作控制需求,设计了微夹持器静电驱动控制系统以及气压控制系统.在80 V的驱动电压下,微夹持器末端夹爪位移可达25 μm.针对100～200 μm的小球进行了微操作实验,实验结果表明,静电梳齿驱动结合真空吸附能够使夹取操作更加稳定,基于闭环控制的气路正压力能有效克服小球与夹爪之间的粘附力,实现可靠的释放操作.微夹持器基本满足100～200 μm微小构件的操作需求.     

柔性并联微夹取器的动力学分析及试验研究

针对一种具有毫米级操作空间和纳米级位移分辨率的、由直线超声电机驱动的柔性并联微夹持器,进行了动力学建模分析和实验研究。基于筷子夹取物体的操作原理,该微夹持器采用并联双层的结构形式。利用单位向量法,基于万向柔性铰链两端面始终平行的假设建立了微夹持器的运动学模型,表明了电机输入与操作末端输出之间的关系。采用ADAMS软件构建了微夹持器的刚柔耦合动力学仿真模型,由反向动力学仿真分析得到了微夹持器运行过程中几个重要的特征参数;由向前动力学仿真分析得到了操作末端,即探针尖端在给定输入函数下的位移、速度和加速度响应参数。对微夹持器的性能测试和夹取实验结果表明,该微夹持器的运行范围为2332μm×2109μm×20000μm,位移分辨率达到0.1μm,能够实现对微小物体的夹取操作。     

一种压电驱动微操作器及其释放位置精度分析

报道了一种利用压电陶瓷双晶片驱动的适用于尺寸在20~200 μm之间微器件装配操作的微操作器。夹持臂尖端直径约15 μm,在80 V的电压驱动下闭合约200 μm的距离。通过理想操作模型分析了微器件释放的位置误差来源和提高微器件释放位置精度的方法,并进行了高分子小球的排列和释放实验。在相对湿度50%的环境下对直径约170 μm的高分子小球的操纵中,实现了2 μm的释放位置精度。实验表明本微操作器能高精度地完成微器件的拾取、移动和释放操作。     

机油冷却器的散热翅片夹持器设计

介绍了一种条形机油冷却器的工作原理和组成部件。针对该条形机油冷却器组件之一,铝制波形网状带孔冲压件——散热翅片在自动装配过程中的抓取问题,阐述了采用真空负压驱动夹持器夹爪的工作原理;设计了其异型真空夹持器的结构;通过试验验证了该夹持器能够抓取散热翅片,且具有很好的可靠性。     

基于MEMS机构装配的微夹持器研究

微夹持器作为末端执行装置,直接决定了微装配的效率。MEMS机构中包含许多微小的活动部件和功能元件,为实现这些微小器件的稳定夹取和自动装配,设计了一种采用压电陶瓷驱动、基于柔性铰链的二级放大微夹持器结构。对该微夹持器的节点应力、刚度及最大张合量等进行了分析计算,并对微夹持器进行了试制。实验与分析结果表明,该夹持器最大张合量是245μm,放大倍数约为12.3倍,满足MEMS机构的装配要求。在此基础上,重点对张合量与夹持力进行了系统测试,通过对测试数据的非线性回归,推导出99.99%可靠度的驱动电压计算公式,实现了微夹持的精确控制。     

面向MEMS微装配的夹持器的设计和实验研究

介绍了一种由PZT（压电陶瓷）驱动的用于MEMS微装配的微夹持器的设计，计算了夹持器本体的放大倍数和刚度,并用ANSYS仿真验证了数学计算的准确性,采用了基于视觉的标定方法，标定了微夹持器刚度、张合量、夹持力以及夹持力和张合量的关系。实验表明：夹持器张合量达280μm，夹持力达0．1N，可精确操作200～2000μm的微齿轮，实现了微行星齿轮减速器的装配。     

基于PLC的核燃料夹爪试验平台控制系统

充分考虑核燃料夹爪实际运行条件,采用可靠的可编程逻辑控制器,利用液压驱动与气压驱动分别实现载荷的上升、下降与夹爪的紧闭、解锁过程,提供了电气硬件与软件设计方案.实际结果表明,该试验平台控制灵活、操作简单、可靠性高,可以有效实现对核燃料夹爪的性能测试.     

由组合气缸驱动的机械手双爪差动平移夹持器

该文针对自动装配设备,设计了由组合气缸驱动的机械手双爪差动平移型夹持器,夹持器能在一个时间节拍中同时完成一爪抓取工件,另一爪将已经抓取的工件放入装配工位实现差动操作,工作效率高;具有自动适应工件尺寸变化、自动对中功能,装配精度高;夹持器由气动系统驱动,简化了机械手的控制系统,结构更简单、体积小、重量轻。     

基于体硅工艺的静电致动微夹持器制作工艺分析

介绍了一种基于体硅工艺的大尺寸、大深宽比梳状静电致动微夹持器的制作工艺。对微夹持器制作中的关键工艺进行分析,重点分析ICP蚀刻工艺的蚀刻时间对结构的影响,总结导致器件失效的原因,探讨了减少失效的方法。加工过程中采用分步加工的办法控制蚀刻时间,成功的释放了宽6μm,厚60μm,等效长度达5470μm的悬臂梁型微夹持臂。研制出一种良好性能的具有S形柔性结构夹持臂的梳状静电致动微夹持器。     

基于体硅工艺的集成式定位平台

针对纳米定位平台的构型和定位精度问题,采用体硅加工技术成功地研制出了一种基于单晶硅并带有位移检测功能的新型二自由度微型定位平台,定位平台采用侧向平动静电梳齿驱动.利用力电耦合和能量守恒原理分析了静电致动器的致动机理,对定位平台的主要失效模型、静态和动态特性进行详细建模分析,证明了静电梳齿力电耦合所导致的侧壁不稳定以及驱动器的最大稳定输出位移,给出了平台稳定工作条件下梳齿间隙、梳齿初始交错长度以及复合柔性支撑梁的弹性刚度比之间的关系.动态分析时考虑空气阻尼对平台的影响,给出了平台最大运行速度、位移及动态条件下的临界驱动电压并把分析结果应用于平台闭环控制.实验结果表明:驱动电压30 V时,平台稳定输出位移达10 μm,机械稳定时间仅为2.5 ms.     

Development of a microgripping system for handling of microcomponents

This paper reports the development of a semi-automatic microgripping system that consists of a microgripper and an x, y, z positioning system. The microgripper has two 1DOF fingers fabricated by an amorphous, soft magnetic material and is actuated electromagnetically. The microgripper is embedded in the 3DOF positioning system with the help of a stainless steel holder under an angle, which is manually adjusted, in respect to the working field. The position of the microgripper is observed optically and by three digital indicators¹ from Mitutoyo, which offer easy reading and continuous position tracking. All axes are actuated by step motors which allow precise positioning of the microparticles under manipulation. The microgripping system was tested in pick and place cases, under an optical microscope in atmospheric conditions. Optical fibres (125 μm in diameter) and bonding wires (50 μm in diameter) were handled. The temperature on the actuator, on the microgripper fingers and on the microgripper tips during manipulation was measured using K type (Ni/CrNi) thermocouples. The gripping force was evaluated as well.     

Haptic controlled three-axis MEMS gripper system

In this work, we describe the development and testing of a three degree of freedom meso/micromanipulation system for handling micro-objects, including biological cells and microbeads. Three-axis control is obtained using stepper motors coupled to micromanipulators. The test specimen is placed on a linear X-stage, which is coupled to one stepper motor. The remaining two stepper motors are coupled to the Y and Z axes of a micromanipulator. The stepper motor-micromanipulator arrangement in the Y and Z axes has a minimum step resolution of ～0.4?μm with a total travel of 12 mm and the stepper motor-X stage arrangement has a minimum resolution of ～0.3?μm with a total travel of 10 mm. Mechanical backlash error is ～0.8?μm for ～750?μm of travel. A MEMS microgripper from Femtotools? acts as an end-effector in the shaft end of the micromanipulator. The gripping ranges of the grippers used are 0-100?μm (for FT-G100) and 0-60?μm (for FT-G60). As the gripping action is performed, the force sense circuit of FT-G100 measures the handling force. This force feedback is integrated to a commercially available three degree of freedom haptic device (Novint Falcon) allowing the user to receive tactile feedback during the microscale handling. Both mesoscale and microscale controls are important, as mesoscale control is required for the travel motion of the test object whereas microscale control is required for the gripping action. The haptic device is used to control the position of the microgripper, control the actuation of the microgripper, and provide force feedback. A LABVIEW program was developed to interlink communication and control among hardware used in the system. Micro-objects such as SF-9 cells and polystyrene beads (～45?μm) are handled and handling forces of ～50?μN were experienced.     

Control and dynamic releasing method of a piezoelectric actuated microgripper

This paper proposes the control and dynamic releasing method of a symmetric microgripper with integrated position sensing. The microgripper adopted in this micromanipulation system is constructed by two L-shaped leverage mechanisms and the fingers of the microgripper is machined much thinner than the gripper body. A combined feedforward/feedback position controller is established to improve the motion accuracy of the microgripper in high frequency. The feedforward controller is established based on rate-dependent inverse Prandtl-Ishlinskii (P–I) hysteresis model. The inertial force generated in dynamic based releasing process is analyzed through MATLAB simulation. Open-loop experimental tests have been performed, and the results indicate the first natural frequency of the microgripper is 730 Hz. Then experiments in high frequency based on the developed combined controller are carried out and the results show the tracking error of a superimposed sinusoidal trajectory with the frequency of 100 Hz, 120 Hz and 130 Hz is 6.4%. Finally, the tiny objects releasing experiments are conducted where the combined controller is used to control the motion amplitude and frequency to achieve inertial force controllable to improve operation accuracy. And the results show that the dynamic releasing strategy is effective.     

毫米级微型机器人操作手的研制和操作特性

采用单晶片型压电悬臂梁制作了一种双悬臂梁结构的微型夹持器,用作毫米级微型机器人的微操作手.该微夹持器整体尺寸为15mm×2mm×2mm,重量为100mg.在分析该悬臂梁操作原理的基础上,选用PbNi_1/3Nb_2/3-PbZrO₃-PbTiO₃三元系压电陶瓷准同型相界的配方作为悬臂梁压电驱动材料,这种压电陶瓷具有高压电常数 (d₃₁) 和机电耦合系数 (K_p).进一步研究了压电微夹持器的操作特性.结果表明:50V电场下,其最大张口距离可以达到40μm,最大夹持力为25.7×10^-3N.     

Back-scatter electron images at 200 kV of subsurface structures in composite materials

Back-scatter electron images of subsurface structures of higher atomic number than the matrix are obtained at accelerating voltages of 50, 100, 150 and 200 kV. Similar back-scatter images of structures on the bottom surface of single crystal foils of copper and mica ranging in thickness from 1 to 4 μm are compared with STEM images. It is concluded that at 200 kV a reasonable resolution of structures down to 1 μm subsurface is possible.     

具有三层结构的SU-8胶V形微电热驱动器

为解决SU-8胶微电热驱动器在工作过程中存在平面外运动的问题,提出了一种具有铜-SU-8胶-铜三层对称结构的新型SU-8胶V形微电热驱动器.采用刚度矩阵方法建立了包含被驱动结构刚度的微电热驱动器力学模型,并针对一种柔性微夹钳,利用该模型对微电热驱动器进行了几何参数设计.利用Ansys仿真软件对所设计微驱动器进行了分析,仿真结果验证了所建模型的合理性.提出了一种新的MEMS加工工艺来制作三层结构微电热驱动器,并测试了它的性能.结果表明,实验结果与仿真结果相差不大,在150mV驱动电压下,所设计微驱动器温度仅升高约32.93℃,并对微夹钳产生约2.5 μm的输入位移,使微夹钳产生126μm的钳口距离改变量.微驱动器仅消耗大约30.35 mW的功率,钳口的平面外运动小于500 nm.最后,利用微电热驱动器驱动的微夹钳成功地对一个长1.2 mm,宽135μm,厚50μm的SU-8胶材料微型零件进行了微操作实验,实验证明了微驱动器实际性能基本满足设计要求.     

一种整体式力敏微型机械手

介绍一种集成有二维力传感器的整体式微型机械手 ,并建立了该机械手的力学模型。该机械手由三组平行片簧构成 ,能同时测量抓取力和沿机械手轴向的装配力。检测结果表明 ,两个集成在机械手中的力传感器互不干涉。