In this work, we introduce an advanced thermo-active variable impedance module which builds upon our previous innovation in thermal-based impedance adjustment for actuation systems. Our initial design harnessed the temperature-responsive, viscoelastic properties of Polycaprolactone (PCL) to modulate stiffness and damping, facilitated by integrated flexible Peltier elements. While effective, the reliance on compressing and the inherent stress relaxation characteristics of PCL led to suboptimal response times in impedance adjustments. Addressing these limitations, the current iteration of our module pivots to a novel 'shear-mode' operation. By conducting comprehensive shear rheology analyses on PCL, we have identified a configuration that eliminates the viscoelastic delay, offering a faster response with improved heat transfer efficiency. A key advantage of our module lies in its scalability and elimination of additional mechanical actuators for impedance adjustment. The compactness and efficiency of thermal actuation through Peltier elements allow for significant downsizing, making these thermal, variable impedance modules exceptionally well-suited for applications where space constraints and actuator weight are critical considerations. This development represents a significant leap forward in the design of variable impedance actuators, offering a more versatile, responsive, and compact solution for a wide range of robotic and biomechanical applications.

翻译：本文介绍了一种先进的热激活变阻抗模块，该模块基于我们先前在驱动系统热基阻抗调节方面的创新成果。最初的设计利用聚己内酯（PCL）的温度响应粘弹性特性，通过集成柔性帕尔贴元件来调节刚度和阻尼。尽管该方案有效，但PCL的压缩依赖性及其固有应力松弛特性导致阻抗调节的响应时间欠佳。针对这些局限性，本迭代模块转向新颖的“剪切模式”操作。通过对PCL开展全面的剪切流变学分析，我们确定了一种消除粘弹性延迟的配置，从而在改善热传递效率的同时实现更快的响应速度。该模块的一大优势在于其可扩展性，且无需额外的机械致动器进行阻抗调节。通过帕尔贴元件实现的热驱动具有紧凑性与高效性，可显著缩小模块体积，使这类热基变阻抗模块特别适用于对空间约束和致动器重量有严格要求的应用场景。这一发展标志着变阻抗致动器设计的重大突破，为机器人和生物力学领域的广泛应用提供了更灵活、响应更快且更紧凑的解决方案。