复合式MEMS微夹持器研制

研制了一种针对亚毫米微小构件实施稳定夹取及可靠释放的微夹持器,应用MEMS体硅工艺将静电梳齿驱动与真空驱动集成构成复合式驱动,设计了微夹持器静电驱动控制系统以及真空控制系统。在80V的驱动电压下,微夹持器末端夹爪位移25μm。设计了两种尺寸的微夹持器,一种张合量为100µm～150µm,另一种为150µm～200µm。针对100～200µm的小球进行了微操作实验,实验结果证明静电梳齿驱动结合真空吸附能够使夹取操作更加稳定,基于闭环控制的正压气流能有效克服小球与夹爪之间的粘附力,实现了可靠的释放操作。     

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。     

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。     

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。     

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。     

新型空间大行程微夹持器的设计与分析

针对传统微夹持器夹持范围小、易对物体造成损伤等不足,基于桥式放大机构和杠杆原理设计了一种新型微夹持器.该微夹持器不仅能完成对不同尺寸大小微物体的微夹持操作,还能避免在微夹持操作过程中对微小物体造成损伤或脱落,以及适应不规则微小物体的夹持操作.阐明了夹持器的结构设计原理,根据微夹持臂的工作原理建立了数学模型,计算了微夹持臂的位移放大率.此外,使用有限元分析软件ANSYS Workbench进行了静力学和动力学仿真,并验证其夹持的有效范围.结果 表明微夹持臂有较大的位移输出,且其放大率的理论计算值与仿真分析值吻合良好.     

面向某微小型平板类零件的微装配系统研究

针对平板类微小型零件装配中出现的自动化程度低、可靠性差的问题,提出基于主机+从控制器+多种传感器的微装配控制系统;设计了吸附式微夹持器代替卡爪式微夹持器,解决了平板类微小型零件难以夹持的问题;同时设计了基于单摄像机的光学自动对位系统,以完成装配件与装配基体之间的精确对位检测.实验中所搭建的微装配系统可较好地完成平板类微小型结构件的装配.     

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。     

电热微夹持器微尺度传热分析与优化设计

针对电热平行梁微夹持器存在的末端夹指高温问题，首先，对电热微夹持器的传热机理进行分析，结合实验得到微尺度下的拟合传热参数；其次，对传统的电热微夹持器末端夹指设计了S型梁散热结构，使用显微红外分析仪对微夹持器对优化效果进行表征；最后，通过微球夹持实验验证了优化设计的可靠性。结果表明，空气自然对流换热系数可达到宏观状态下的60~300倍，在此数据基础上进行的优化设计可以使末端夹指温度降低约45%。该优化方案对其他材料或结构的电热微夹持器也具有一定的通用性。     

一种刚柔结合柔性夹持器的设计

为解决传统刚性夹持器适应性差和软体夹持器夹持范围较小的问题,提出了一种刚柔结合柔性夹持器的设计方案,其中刚性的曲柄滑块机构采用铝合金材料制作,柔性的气动软体驱动器则由乳胶气囊以及纤维布两部分组成。通过滑块平移带动夹爪转动,实现夹爪张开和闭合,再通过调整供气气压控制夹持范围。基于ADAMS软件对刚性机构进行运动学分析,再仿真并结合实验,研究气动软体驱动器的动态特性,确定其最佳尺寸。最后,对样机进行实验测试,实验结果表明,设计的夹持器自适应性好、夹持范围较大。     

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。     

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.     

Computational parametric analysis and experimental investigations of a compact flexure-based microgripper

This paper presents a flexure-based piezoelectric actuated microgripper for high precision grasping/releasing tasks. The design of the microgripper consists of a three-stage amplification and transmission mechanism, and the parallel grasping technique. A bridge-type mechanism and two sequential lever-type mechanisms are symmetrically connected to amplify the output displacement of the embedded piezoelectric actuator. The parallelogram mechanisms assist in linearizing the output displacement of both jaws of the microgripper. The computational analysis is conducted to investigate the effect of the dimensional parameters on the characteristics of the microgripper. A computational parametric optimization methodology is established to achieve the required attributes of the microgripper. The design optimization resulted in a compact design, a high displacement amplification ratio, and a large output displacement of the microgripper. The experimental studies are conducted to investigate the key characteristics of the microgripper such as the displacement amplification ratio, the output displacement, tracking performance. Further, the parasitic motion, input-end and output-end motion resolution of the microgripper are identified. The experimental results indicate that the compact microgripper can achieve a high displacement amplification ratio and large output displacement with a high positioning accuracy.     

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.     

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.     

Design and analysis of flexure-hinge parameter in microgripper

In the precision engineering field, a large number of applications require precise and microlevel manipulations, and microgrippers are an essential device to achieve precise manipulations. Highly precise movements are, in general, hard to achieve using conventional joints due to manufacturing error and backlash. In this paper, a new two-dimensional, compliant, monolithic piezo-actuated microgripper using flexure hinges is reported. The microgripper is designed, and a comparison study on stress and displacement is done by varying the hinge parameters such as the hinge radius, web thickness, position of flexure hinge, and radius of curvature of hinges. Kinematics of the microgripper is analyzed based on input/output displacement for all the above hinge design variations using FEM, and a kinematic model is arrived at based on the hinge location.     

压电陶瓷微夹钳迟滞环自适应逆控制研究

针对压电陶瓷的迟滞特性可使微夹钳难以获得良好的位移控制的问题，提出自适应逆控制策略。推导了压电悬臂位移特性的理论模型；采用自适应最小均方算法滤波器建立了压电悬臂的基于Backlash算子的迟滞环正逆模型，并以此为基础建立了微夹钳位移的自适应逆控制系统。样机测试和跟踪实验结果验证了所建立的理论模型和迟滞环模型的正确性，以及控制系统良好的自学习能力和控制效果。