基于形状记忆合金的变刚度外骨骼设计与建模

Design and modeling of variable stiffness exoskeleton based on shape memory alloy

为减轻变刚度驱动单元质量,缩小其体积,提出一种基于形状记忆合金(SMA)的变刚度主动元,单个变刚度主动元质量约为68.5 g.为精确控制外骨骼刚度,结合SMA本构模型、相变动力学模型、热平衡方程、输出方程,对SMA进行动态建模.为最大化满足人体运动需求,通过并行布置变刚度主动元的方式,结合导轨机构,构建轻质变刚度外骨骼的原理样机.测试结果显示外骨骼变刚度范围为7~20 N/mm,验证了外骨骼功能的有效性.

To reduce the mass and the volume of the variable stiffness driving unit,an active variable stiffness unit based on shape memory alloy(SMA) was proposed, and the single active variable stiffness unit weighed about 68.5 g. To precisely control the stiffness of the exoskeleton,the SMA constitutive model,phase dynamics model,heat balance model,and output equation were combined to build the dynamic model of SMA. To meet the needs of human movement as much as possible, a light-weight variable-stiffness exoskeleton prototype was constructed by arranging active variable stiffness units in parallel and combining the guide rail mechanism. Test results show that the exoskeleton variable stiffness ranges from 7 N/mm to 20 N/mm, verifying the effectiveness of the exoskeleton function.