Surgical Knife Locking Feature for Axial Load Transfer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing robotic surgical systems face challenges in efficiently cutting tissue due to limitations in knife design and attachment, which can lead to premature failure and reduced precision.
Innovation Solution
The end effector includes a knife with a locking feature that securely attaches to a retention feature on the drive rod, providing axial constraint and load transfer, thereby preventing premature failure and enhancing cutting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a knife is attached to a drive rod in conventional surgical end effectors, then the knife can advance and retract to cut tissue, but the knife may separate from the drive rod prematurely during use
Solution Approach 1:
The knife attachment system is segmented into distinct functional components: a retention feature on the drive rod and a locking feature on the knife. This segmentation allows each component to be optimized independently for its specific function while working together to prevent premature separation during cutting operations.
Solution Approach 2:
The retention feature acts as an intermediary element between the drive rod and the knife. This intermediate structure provides a dedicated interface that transfers axial loads from the knife to the drive rod, preventing direct stress on the knife-drives rod interface and eliminating premature failure.
2Ease of manufacture
If the knife design is simplified for ease of manufacture, then production cost decreases, but cutting precision and durability are reduced
Solution Approach 1:
The knife is segmented into functional zones including a cutting edge portion for precision cutting and a locking feature portion for secure attachment. This segmentation allows the cutting edge to be optimized for precision while the locking feature is optimized for secure attachment, with each portion manufacturable using appropriate processes.
Solution Approach 2:
Different portions of the knife have different local qualities optimized for their specific functions. The cutting edge has a sharp, precise geometry for accurate tissue cutting, while the locking feature has a geometry optimized for engagement with the retention feature. This local quality differentiation maintains cutting precision without requiring complex manufacturing throughout the entire knife structure.
3Reliability
If the knife attachment mechanism is made more secure to prevent separation, then reliability improves, but the complexity of the device increases
Solution Approach 1:
The retention feature and locking feature are designed to work together as an integrated attachment system. The retention feature on the drive rod and the locking feature on the knife combine to provide secure attachment and load transfer, preventing the need for additional separate retention mechanisms and keeping the overall system simple.
Solution Approach 2:
The locking feature is designed to automatically engage with the retention feature through axial movement of the knife relative to the drive rod. This self-acting mechanism eliminates the need for external actuators or complex retention systems, maintaining simplicity while ensuring reliable attachment during cutting operations.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A surgical tool includes a drive housing having opposing distal and proximal ends, first and second drive cable capstans arranged within the drive housing and asymmetrically aligned between the distal and proximal ends, a first drive cable extending distally from the drive housing and actuatable by operation of the first drive cable capstan, and a second drive cable extending distally from the drive housing and actuatable by operation of the second drive cable capstan. A stiffness of the first and second drive cables is equalized by adjusting one or more characteristics of one or both of the first and second drive cables.