Artificial Tendons Improve Fault-Tolerance of Robotic Arms Under Free-Swinging Failures

In hazardous environments, the deployment of robotic arms that can withstand failures without compromising task performance is crucial. This paper focuses on enhancing the fault tolerance of robotic arms, specifically addressing free-swinging failures, which have been less explored compared to locked-joint failures in prior studies. To mitigate the impact of free-swinging failures, a novel fault-tolerance structure is proposed, incorporating artificial tendons (elastic strings) along both sides of the robotic arm segments. These artificial tendons are designed to generate torques at the joints in the event of a failure, enabling the robotic arm to retain its ability to move within certain regions of the workspace, defined as the fault-tolerant workspace (FTWS). Comparative analysis in both planar and spatial scenarios demonstrates that the robotic arm equipped with artificial tendons exhibits a significantly larger FTWS than one relying solely on locking the failed joint, provided that a free-swinging failure is detected. The findings from this research present innovative avenues for the design and development of fault-tolerant robotic arms.