Compliant Deflection Devices for Trocar Tool Centering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In robotic surgery, trocar assemblies and surgical tools often do not have a 1:1 pairing, leading to 'lost motion' or hysteresis issues such as deflection, oscillation, and vibration when smaller diameter surgical tools are used through larger diameter trocar assemblies, which compromises the precision and control expected by surgeons.
Innovation Solution
Incorporating compliant deflection devices with radial biasing members at the distal end of the trocar cannula, these devices extend radially inward to center surgical tools of varying diameters, minimizing unintended oscillation and vibration by accommodating larger tools without obstructing them and returning to their relaxed state when the tool is removed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a larger diameter trocar assembly is used to accommodate smaller diameter surgical tools, then the versatility of the trocar assembly is improved, but the precision and control of the surgical tool are worsened due to lost motion and hysteresis
Solution Approach 1:
The patent applies local quality by providing compliant deflection devices at specific locations (distal end and intermediate positions) within the trocar assembly. These devices create localized contact points that center the surgical tool without requiring the entire trocar interior surface to be precision-machined, thus maintaining versatility while improving precision control.
Solution Approach 2:
The compliant deflection devices act as intermediaries between the trocar assembly wall and the surgical tool. These devices transmit centering forces to the tool while accommodating dimensional variations, thereby eliminating lost motion and hysteresis without compromising the adaptability of the trocar assembly to different tool sizes.
2Manufacturing precision
If compliant deflection devices are added to center surgical tools, then the precision and control are improved, but the device complexity increases
Solution Approach 1:
The patent employs flexible, compliant deflection devices that can be simple annular elements or thin-walled structures. These flexible components provide the necessary centering function through elastic deformation rather than complex mechanical mechanisms, thereby improving precision while minimizing the increase in device complexity.
Solution Approach 2:
The compliant deflection devices are segmented into discrete elements (such as multiple radially-spaced contacts or segmented annular structures) that can be independently positioned. This segmentation allows the centering function to be distributed throughout the trocar assembly, improving precision without requiring a single complex centering mechanism.
3Manufacturing precision
If radial biasing members extend inward to center smaller tools, then the precision is improved, but the obstruction to larger tools may increase
Solution Approach 1:
The compliant deflection devices are designed with dynamic compliance, allowing them to flex and adapt their radial extension based on the diameter of the inserted surgical tool. When a smaller tool is inserted, the devices extend radially inward to provide centering contact. When a larger tool is inserted, the devices flex outward to accommodate the larger diameter, thereby improving precision for small tools without obstructing larger ones.
Solution Approach 2:
The patent utilizes parameter changes in the physical state of the compliant deflection devices, specifically their degree of radial extension. By changing the radial position parameter of these devices based on the tool diameter, the system achieves precise centering for smaller tools while maintaining ease of operation for larger tools without obstruction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The compliant deflection devices effectively center surgical tools within the trocar cannula, reducing unwanted motion and vibration, thereby enhancing precision and control during robotic surgical procedures by accommodating tools of different diameters without obstructing larger ones.
Implementation Method 1
a radial biasing member that extends radially inward toward a centerline of the cannula to center a surgical tool within the lumen
Implementation Method 2
each compliant deflection device includes a radial biasing member that extends radially inward toward a centerline of the cannula to center a surgical tool within the lumen and minimize unintended oscillation and vibration of the surgical tool
Data Source
AI summary
A trocar assembly includes a trocar housing that defines a working chamber, and a cannula having opposing proximal and distal ends and defining a lumen that extends between the proximal and distal ends. One or more windows are defined in the cannula at or near the distal end, and one or more compliant deflection devices are arranged at or near the distal end and at least partially receivable within the one or more windows. Each compliant deflection device includes a radial biasing member that extends radially inward toward a centerline of the cannula.