Spherical Wrist Roll Control for Precise Surgical Robotics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing surgical robotic systems face challenges in achieving precise and stable roll movements of surgical instruments due to inherent tracking errors from multiple degrees of freedom, which can compromise the accuracy and stability of the instrument tip during microsurgery.
Innovation Solution
A surgical robotic system incorporating a spherical wrist with a yaw, pitch, and roll axis, actuated by a drive assembly through an elongated shaft and a preloaded string, allowing for improved accuracy and reduced play in the kinematic structure, enhancing the precision and control of surgical instruments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a surgical robotic system uses multiple degrees of freedom to achieve roll movement, then the instrument can perform complex maneuvers, but tracking errors accumulate and reduce positioning accuracy
Solution Approach 1:
The system segments the roll movement function by providing a dedicated roll axis that is independently actuated, separating it from other degrees of freedom. This allows the roll movement to be controlled directly without relying on combinations of multiple joints, thereby eliminating cumulative tracking errors while maintaining full movement capability.
Solution Approach 2:
A dedicated roll actuator serves as an intermediary component that directly controls the roll degree of freedom. This intermediary mechanism ensures precise control of the roll movement independent of other joints, preventing error propagation from multiple degrees of freedom while enabling the instrument to perform complex maneuvers.
2Manufacturing precision
If the spherical wrist includes a dedicated roll axis with independent actuation, then positioning accuracy and stability are improved, but device complexity increases
Solution Approach 1:
The spherical wrist mechanism is designed with multi-functionality, where the same structural components serve multiple purposes. The roll axis shares structural elements with other degrees of freedom in the spherical wrist, allowing the system to achieve precise roll control without proportionally increasing overall device complexity.
Solution Approach 2:
The system merges the roll actuation mechanism with the existing spherical wrist structure, combining multiple functions into integrated components. This merging approach allows the dedicated roll axis to be implemented while minimizing additional complexity by sharing common structural and control elements with other degrees of freedom.
3Manufacturing precision
If a preloaded string is used to actuate the surgical instrument, then play and friction are reduced improving precision, but the mechanism becomes more complex
Solution Approach 1:
The system replaces traditional mechanical actuation mechanisms with a string-based actuation system. The preloaded string eliminates the need for complex mechanical linkages, gears, or belts, reducing play and friction while maintaining actuation precision. The string mechanism is simpler in principle, though it introduces new considerations for tension control and routing.
Solution Approach 2:
The preloaded string actuation system changes the physical parameters of the actuation mechanism by introducing controlled tension through preloading. This parameter change (applying constant tension) eliminates backlash and reduces friction, improving precision without requiring complex mechanical adjustments or variable mechanisms.
Data Source
AI summary
A surgical robotic system is provided comprising a wrist comprising a surgical instrument and an elongated shaft configured to transmit actuation forces from a drive assembly to the spherical wrist to actuate rotation of the spherical wrist. The surgical instrument is a hinged surgical instrument comprising jaws, wherein the jaws are biased in a normally open position by a resilient biasing element, wherein the surgical instrument is actuatable by the drive assembly towards a closed position by a preloaded string which runs from the drive assembly through the elongated shaft to the surgical instrument and which preloads the surgical instrument.