Design of roller-cam clutch mechanism for energy efficiency and high backdrivability of lower extremity exoskeleton

Abstract

In this paper, a roller-cam clutch (RCC) mechanism was developed. The RCC can transfer bidirectional torque with high backdrivability, as well as increase actuation energy efficiency, in electrical exoskeleton robots. The developed mechanism was installed at the knee joint, which uses less metabolic energy, and unclutched during the swing phase, thereby functioning as a passive joint. The RCC aimed to increase actuation energy efficiency, and by generating zero impedance for users during the swing phase, to produce high backdrivability. To develop the mechanism, mathematical modeling of the RCC was conducted, with the design having more than three safety factors following optimization. Titanium (Ti-6AL-4V) material was used. Finally, modeling verification was done using ANSYS software.