Alternative Solutions to Tendon-Driven Hyper-Redundant Manipulators: A Review on Design and Actuation Strategies

Due to their distinctiveness and potential uses, hyper-redundant manipulators are becoming increasingly relevant in robotics research. The high number of degrees of freedom makes them suitable for various applications across various fields, including inspection, minimally invasive surgery, and space applications. These manipulators are especially useful where high manoeuvrability is needed, particularly in constrained environments, thanks to their abundance of degrees of freedom. While having significant benefits, this redundancy introduces complexities in developing robust actuation and innovative designs. This work is the second of two parts of a survey conducted on hyper-redundant manipulators, analyzing continuum, and rigid-link manipulators. The aim of this survey is to provide a comprehensive analysis of non-tendon-driven hyper-redundant manipulators, examining their unique design and actuation strategies and identifying their potential advantages and challenges compared to tendon-driven counterparts. By focusing on these alternatives, this survey seeks to expand the understanding of hyper-redundant manipulator technology and highlight innovative approaches in this evolving field. The article synthesizes recent advancements, explores various designs, and identifies critical challenges.