Analysis of Human Intrinsic Stiffness Modulation and its Use in Variable-Stiffness Robots

This Thesis explores how human are able to modulate intrinsic hand and arm stiffness. The question is increasingly relevant as human and robots start collaborating inside same workspaces and introducing compliance allows tuning forces due to impacts, e.g., by using variable-stiffness actuators VSAs. However, even if an endless amount of different mechanisms for VSA have been introduced, design criteria regarding their mechanical properties remain unclear. This Thesis describes the development of special mechanisms for revealing insights into reflex-free, mechanical, human hand and arm compliance-behavior and special attention is paid to investigate human capabilities to decouple stiffness from force. Conclusively, the transfer of gained insights to robotic systems is analyzed and discussed