Frictional influences in tendon-driven robotic systems are generally
unwanted, with efforts towards minimizing them where possible. In the human
hand however, the tendon-pulley system is found to be frictional with a
difference between high-loaded static post-eccentric and post-concentric force
production of 9-12% of the total output force. This difference can be directly
attributed to tendon-pulley friction. Exploiting this phenomenon for robotic
and prosthetic applications we can achieve a reduction of actuator size, weight
and consequently energy consumption. In this study, we present the design of a
bio-inspired friction switch. The adaptive pulley is designed to minimize the
influence of frictional forces under low and medium-loading conditions and
maximize it under high-loading conditions. This is achieved with a
dual-material system that consists of a high-friction silicone substrate and
low-friction polished steel pins. The system, designed to switch its frictional
properties between the low-loaded and high-loaded conditions, is described and
its behavior experimentally validated with respect to the number and spacing of
pins. The results validate its intended behavior, making it a viable choice for
robotic tendon-driven systems.Comment: Conference. First submission, before review
