Bio-Inspired Tensegrity Robotic Wrist With Tendon Sheath Functionality

Conventional robotic wrists predominantly employ rigid structures, which exhibit significant limitations in adaptability, while flexible robotic wrists often face challenges, such as insufficient stability and complex actuation system. Inspired by the bone-ligament composite structure of the human wrist, this study proposes a bio-inspired tensegrity mechanism that replicates functionality of wrist through kinematic mapping. By constraining the degrees of freedom (DOF) of the structure, we designed a biomimetic wrist with a workspace covering the human wrist’s motion range, achieving a balance between flexibility and stability. Furthermore, we investigated the role of tendon sheaths in wrist motion and simulated their function using eyebolt to guide tendon routing, enabling effective motion control. Impact test demonstrated the wrist’s rapid recovery ($0.6 \, \mathrm{s}$) to equilibrium after disturbance, with steady-state recovery rates of 99.73% (coronal plane) and 99.86% (sagittal plane), highlighting its superior stability. Laser-tracing experiment further validated the wrist’s capability to execute complex trajectory-tracking tasks. Finally, the potential of this robotic wrist for practical applications was demonstrated through both load-bearing and dynamic variable loading tests.