A Two-Segment 7-DOF Miniature Flexible Parallel Manipulator Toward Minimally Invasive Transluminal Endoscopic Surgery

Minimally invasive transluminal endoscopic surgery provides access to deep and narrow spaces, significantly reducing tissue damage and shortening recovery time. However, conventional endoscopic manipulators are constrained by inadequate flexibility and miniaturization, making it difficult to perform surgical procedures effectively in these challenging environments. In this article, we propose a 2-mm flexible parallel manipulator with 7 degrees of freedom (DOFs), composed of a two-segment parallel mechanism. The flexible parallel manipulator with a 0.6-mm hollow structure that incorporates an instrument channel is driven by the tendon-sheath mechanism, enabling the flexible parallel manipulator to achieve dexterous operation while maintaining a compact size. The screw theory is applied to establish the kinematics and stiffness model of the flexible parallel manipulator, where the Jacobian and stiffness matrix of the flexible parallel manipulator can be obtained in different configurations. The reachable and dexterity of the proposed flexible parallel manipulator are analyzed in detail. A series of experiments, including stiffness and teleoperation accuracy tests, are conducted to verify the mechanical properties of the flexible parallel manipulator. The feasibility of the proposed manipulator is demonstrated by the results of in-vivo test.