Parametric Design of a Soft Gripper Actuated Using the Electrostrictive PVDF-Based Terpolymer
Parametric Design of a Soft Gripper Actuated Using the Electrostrictive PVDF-Based Terpolymer
复制标题
使用电致伸缩 PVDF 基三元共聚物驱动的软夹具的参数化设计
DOI：
10.1115/smasis2018-7966
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
M. Frecker
中科院分区：
文献类型：
--
作者：
Wei Zhang;Jonathan Hong;Saad Ahmed;Z. Ounaies;M. Frecker
如今，使用柔性机构而不是刚性部件来实现抓取动作的软夹具由于其材料选择、高顺应性和与目标物体的温和接触而被用于越来越多的工程领域，例如食品工业、医疗保健和生物样品收集，与传统的刚性夹具相比。在这项研究中，一个三指夹持器设计的基础上，一个简单的驱动机构，但具有较高的适应性的对象，并产生相对较高的驱动力每单位质量。电致伸缩PVDF基压电陶瓷作为自折叠驱动机构。建立了夹持器在包络抓取和平行抓取两种抓取模式下的有限元分析模型，对夹持器的折叠变形和抓取力进行了预测。有限元模型与实验结果吻合较好。设计优化，然后制定和参数化设计进行的目标，最大限度地提高自由偏转和阻挡力的夹持器。设计变量是有源和无源材料的厚度以及无源层的性质。结果表明，对于给定的透明胶带基底厚度，存在一个最佳的透明胶带厚度，以获得最大的自由挠度，并且阻挡力总是随着透明胶带或透明胶带厚度的增加而增加。随着凹口的长度增加，由于致动器的更明显的折叠行为，自由偏转也增加，但是由于致动器的刚度较小，阻挡力减小。自由偏转和阻挡力之间的权衡对于特定应用的最佳设计的最终决定至关重要。
Nowadays, soft grippers, which use compliant mechanisms instead of stiff components to achieve grasping action, are being utilized in an increasing range of engineering fields, such as food industry, medical care and biological sample collection, for their material selection, high conformability and gentle contact with target objects compared to traditional stiff grippers. In this study, a three-fingered gripper is designed based on a simple actuation mechanism but with high conformability to the object and produces relatively high actuation force per unit mass. The electrostrictive PVDF-based terpolymer is applied as the self-folding actuation mechanism. Finite element analysis (FEA) models are developed to predict the deformation of the folded shape and grasping force of the gripper with two grasp modes, i.e. enveloping grasp and parallel grasp. The FEA models achieved good agreement with experiments. Design optimization is then formulated and a parametric design is conducted with objectives to maximize free deflection and blocked force of the gripper. The design variables are the thicknesses of the active and passive materials, and the nature of the passive layer. It is found that there exists an optimal terpolymer thickness for a given scotch tape substrate thickness to achieve maximum free deflection, and the blocked force always increases as either thickness of terpolymer or scotch tape increases. As the length of the notch increases, free deflection also increases due to more pronounced folding behavior of the actuator, but the blocked force decreases since the actuator is less stiff. The tradeoff between free deflection and blocked force is critical for the final decision on the optimal design for a particular application.