TVIM: Thermoactive Variable Impedance Module Evaluating Shear-Mode Capabilities of Polycaprolactone

This paper presents a significant advancement in the field of thermoactive variable impedance modules by building upon prior research focused on utilizing thermal-induced changes in impedance within actuation systems. The initial design leveraged the temperature-dependent properties of Polycaprolactone (PCL) alongside Peltier elements to modulate stiffness and damping. However, this reliance on compressive forces and the inherent stress relaxation of PCL contributed to prolonged response times in the system. The newly developed module addresses these limitations by operating in a ‘shear mode’, fundamentally enhancing both heat transfer and response speed, as validated through comprehensive shear rheology analysis of PCL. A standout feature of the revised design is its scalability, which effectively eliminates the necessity for additional mechanical actuators. The compact nature of this thermal actuation solution supports effective miniaturization, making it exceptionally suitable for scenarios where space and weight are at a premium. This development represents a valuable innovation in variable impedance actuators for applications in robotics and biomechanics, where constant adaptation of impedance is less critical, providing a pragmatic solution for environments that demand agile yet compact actuation capabilities.