Gravity-Assisted Shape-Locking Articulated Discrete Serial Robot for Ceiling-Mounted Manipulation in Patient Care

Abstract

Continuum robots are promising for assistive manipulation, but often lack the stiffness and payload capacity required for real-world tasks. This paper investigates the feasibility of a novel dual-mode, gravity-assisted ceiling-mounted articulated discrete serial robot that transitions between passive and active states using a friction-based shape-locking mechanism. In passive mode, joints are unlocked, allowing for chain-like flexibility similar to that of ceiling hoists. In active mode, joints are locked, allowing for rigid and accurate manipulation. To evaluate feasibility, we implemented a reduced-scale prototype with two passive joints and one active joint. We tracked its accuracy across 300 iterations of point-to-point motion in a 2D plane. Results show high repeatability and robustness, highlighting the potential of this architecture for ceiling-mounted manipulation. Beyond healthcare tasks such as patient handling, this approach contributes a scalable actuation and shape-locking strategy for articulated discrete serial robots in constrained environments.