形状记忆合金变刚度软作动器设计

Design of Variable Stiffness Soft Actuator Driven by Shape Memory Alloy

软体材料作动器具有良好的目标抓取适应性,为实现软作动器结构的轻量化,保证抓取与承载能力,采用形状记忆合金丝作为驱动元件,设计出一种可变刚度的软作动器。首先,基于形状记忆合金(shape memory alloy,简称SMA)一维本构关系建立了作动器的弯曲变形力学模型;其次,通过实验对力与变形之间的关系进行了验证,弯曲变形与理论结果一致;最后,通过回弹结构的动力学设计,使得该作动器能够在恢复阶段快速回到初始形态。实验结果显示,加热用于变刚度的形状记忆合金丝可显著提升作动器的负载能力,从而达到变刚度的效果。

The soft gripper exhibits high adaptability when grasping a target.In order to achieve the lightweight design while ensuring capacity of grasping and carrying,the shape memory alloy(SMA)wire is utilized as the actuation source in the paper.The phase transformation characteristics of shape memory alloys are applied to perform the variable stiffness task of a soft actuator.The one-dimensional constitutive model of the shape memory alloy is established to construct the theoretical model of the bending angle of the actuator.In addition,the deformation test for shape memory alloy is carried out.Obtained results show that the theoretical model can reflect the actual bended angle.Moreover,when the SMA wire for variable stiffness is heated,the load-bearing capacity of the actuator is notably improved.