A Redundant Parallel Continuum Manipulator With Stiffness-Varying and Force-Sensing Capability

This paper presents the design, analysis, and validation of a novel redundant planar parallel continuum manipulator (PCM) consisting of four flexible links coupled at the rigid mid-and end-platform. To address complex geometry/static hybrid constraints at the rigid platforms, a general framework is developed for the kinetostatics modeling and analysis. Benefiting from the redundant actuation design, the Cartesian stiffness of the studied PCM can be further adjusted as a secondary task to positioning. Utilizing the proposed deflection-based force sensing method, the external load exerted on the end-effector can also be identified by measuring the pose of rigid platforms. To validate the proposed design, a prototype is built, on which a series of experiments have been conducted. The results show that, with the proposed kinetostatics models, the prototype exhibits a mean position and orientation error of 0. 52 mm and 0. 41 ^. Finally, the capability of stiffness-varying and force-sensing is demonstrated to verify the feasibility and potential applications of the designed redundant PCM. Note to Practitioners —This paper is motivated by the need for more adaptable robotic systems in industrial and interactive settings. In this work, a novel redundant parallel continuum manipulator with variable passive compliance and force-sensing capability is presented. This planar manipulator comprises four flexible limbs, each driven by independent linear modules, thus the redundancy in the actuation can be leveraged for varying Cartesian stiffness. By means of measuring the pose of the end-effector, the interaction force exerted on the end-effector can be identified according to the force sensing model. The structural compliance of the manipulator enhances safety in human-robot collaboration, while variable stiffness accommodates the specific requirements of different interaction tasks. Furthermore, the force-sensing capability allows for precise feedback control, significantly improving safety during interactions with humans. Therefore, the presented PCM has the potential for interactive manipulation applications, including delicate and fragile object handling, as well as human-robot collaboration in assembly tasks.