Development of a novel flexure-based microgripper for high precision micro-object manipulation

Micro-scaled parts with dimension below 1 mm need to be manipulated with high precision and consistency in order to guarantee successful microassembly process. Often these requirements are difficult to be achieved particularly due to the problems associated with the structural integrity of the grasping mechanism which will affect the accuracy of the manipulation. Furthermore, the object's texture and fragility imply that small perturbation by the grasping mechanism can result in substantial damage to the object and leads to the degradation of its geometry, shape, and quality. This paper focuses on the unification of two designing approaches to develop a compliant-based microgripper for performing high precision manipulation of micro-objects. A combination of Pseudo Rigid Body Model (PRBM) and Finite Element Analysis (FEA) technique has proven to improve the design efficiency by providing the essential guideline to expedite the prototyping procedure which effectively reduces the cost and modeling time. An Electro Discharge Machining (EDM) technique was utilized for the fabrication of the device. Series of experimental studies were conducted for performance verification and the results are compared with the computational analysis results. A high displacement amplification and maximum stroke of 100 μm can be achieved.     

Development of a piezoelectric polymer-based sensorized microgripper for microassembly and micromanipulation

This paper presents the design, fabrication, and calibration of a piezoelectric polymer-based sensorized microgripper. Electro discharge machining technology is employed to fabricate the superelastic alloy-based microgripper. It was experimentally tested to show the improvement of mechanical performance. For integration of force sensor in the microgripper, the sensor design based on the piezoelectric polymer polyvinylidene fluoride (PVDF) film and fabrication process are presented. The calibration and performance test of the force sensor-integrated microgripper are experimentally carried out. The force sensor-integrated microgripper is applied to fine alignment tasks of micro opto-electrical components. Experimental results show that it can successfully provide force feedback to the operator through the haptic device and play a main role in preventing damage of assembly parts by adjusting the teaching command.The authors wish to thank Mr. Sang-Min Kim for technical assistance. This work was supported by the 21st Centurys Frontier R&D Projects, under the contract number MS-02–324–01, sponsored by the Ministry of Science and Technology, Korea.     

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.     

能动式微夹钳的研究

采用形状记忆合金的形状记忆效应为动力 ,设计研究成功了一种微小型能动式微夹钳 ,阐述了这种微夹钳的动作原理、结构及驱动与控制电路的设计思想 ,汇总了设计研制过程中所作的试验及测试数据 ,并为微夹钳的成功设计与研究提供了依据     

Development of a high precision flexure-based microgripper

This paper presents the design and development of a high precision microgripper for micromanipulation. The design is based on a hybrid flexure-based compliant mechanism and a bias spring structure which render high fidelity and inherent mechanical advantages. Finite element analysis (FEA) was conducted to evaluate responses of the model under specified load and displacement to investigate optimum design of the model. The prototype of the proposed microgripper was fabricated using electro-discharge machining (EDM) process. An experimental study of the performance was carried out and the results are presented. The experimental results are also compared with the computational analysis results. The results show that a high level of displacement amplification and a maximum stroke of 100 μm can be achieved.     

电热驱动镍微夹钳的设计及制作

为实现微系统产业化开发适用于微型零件操作和装配的微夹钳,采用电热驱动方式、V形梁阵列式电热驱动器为钳体部分提供输入位移,钳体部分应用拓扑优化方法进行设计以实现输入位移放大.金属镍作为制作微夹钳的材料,用紫外光刻微电铸脱模技术工艺制作了电热镍微夹钳.通过正交试验,得到加工SU-8铸模的最优工艺参数,对影响工艺质量的各个因素进行详细讨论并给出解决方法,并加工出了钳体尺寸在毫米量级,最小特征尺寸为10 μm,厚度为30 μm的电热微夹钳.对制作的微夹钳在0～2.5 V直流电压下进行动态测试,夹持端位移最大可达67μm,最大夹持力可达0.8 N,可以满足微机电系统微操作的夹持要求.     

A new design of piezoelectric driven compliant-based microgripper for micromanipulation

This paper describes the development of a microgripper mechanism capable of delivering high precision and fidelity manipulation of micro objects. The mechanism adopts a flexure-based concept on its joints to address the inherent nonlinearities associated with the application of conventional rigid hinges. A combination of two modeling techniques namely Pseudo Rigid Body Model (PRBM) and Finite Element Analysis (FEA) was implemented to expedite the prototyping procedure which leads to the establishment of high performance mechanism. A wire Electro Discharge Machining (EDM) technique was utilized to fabricate the monolithic structure of the gripper mechanism. Experimental studies were conducted on the model prototype to obtain various correlations governing the gripper performance as well as for model verification. The experimental results demonstrate a high level of integrity in comparison to the computational analysis. A high amplification characteristic and maximum stroke of 100 μm can be achieved.     

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。     

微夹钳技术发展现状及应用研究

微夹钳是最典型的微执行器,它可以充当机器人手爪,配合各种多自由度驱动装置成为微机器人。微夹钳单元技术与微装配、微操作、微焊接、微封装等系统技术紧密地联系在一起。由于它的重要性和广泛的应用,近年来已成为微机械领域研究的热点。本文首先介绍了微小领域中物体夹持的物理背景,阐述了粘附力的规律和解决方法;详细介绍了已有的微夹钳的研究进展状况,结合作者的科研工作,阐述了有代表性的几种微夹钳的工作原理及工艺制作方法;指出了微夹钳的发展和功能优化方向,以期对微夹钳的研究工作起到一定借鉴作用。