Design of Transmission Tubes for Surgical Concentric Push-Pull Robots

Area of Science:

• Robotics
• Mechanical Engineering
• Biomedical Devices

Background:

• Concentric push-pull robots used in endoscopes require transmission tubes with specific stiffness properties.
• Optimal performance necessitates high axial stiffness, high torsional stiffness, and low bending stiffness.
• Existing laser-cut patterns struggle to independently achieve high axial and low bending stiffness due to coupled properties.

Purpose of the Study:

• To develop a new laser material removal design approach for transmission tubes.
• To overcome the stiffness coupling challenge in laser-cut patterns.
• To independently balance axial, torsional, and bending stiffness for improved robot performance.

Main Methods:

• Proposed a novel design leveraging local stiffness asymmetry in discrete bending segments.
• Segments were separated by solid tube sections and rifled for global stiffness symmetry.
• Utilized finite-element analysis to study design properties and effects of tube interference.

Main Results:

• The discrete asymmetric segment design effectively breaks the stiffness coupling.
• Achieved superior high axial and torsional stiffness compared to previous laser patterns.
• Maintained low bending stiffness comparable to existing methods.

Conclusions:

• The proposed discrete asymmetric segment design offers a viable solution for optimizing transmission tube stiffness.
• This approach enables independent control over axial, torsional, and bending stiffness.
• The findings are crucial for enhancing the performance of endoscopic robots.