Modeling of flexible arm with triangular notches for applications in single port access abdominal surgery

This paper presents a mechanical model of a flexible manipulator arm which will be utilized in the robot system for single port access abdominal surgery. The flexible arm can provide large rotation, which is constructed from a superelastic Nitinol tube with triangular notches. The manipulator arm with bilateral staggered notches is driven in plane by cables embedded in bilateral symmetry channels of Nitinol tube. A cross-configuration of two segments can achieve two bending degrees of freedoms (DOFs). In addition, the proposed design makes the manipulator possible to transfer multi-DOF motions because it has a large open lumen for driven cables, power and signal wires. Based on Timoshenko´s beam theory, a mechanical model of the flexible manipulator arm with triangular notches is established. The analysis data of the mechanical model match the actual experimental results which demonstrate the effectiveness of the proposed mechanical model and indicate the application potential of the system design in the single port access abdominal surgery.