Compliant Surgical Device Tendon Spring Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Surgical instruments and entry guides that navigate convoluted paths, such as natural lumens, require flexibility and stability to avoid damaging adjacent tissue, while existing technologies often react to external forces with unintended movements or springback, potentially harming tissue.
Innovation Solution
The use of compliant surgical devices with tendon systems and constant or asymmetric spring systems to control tension, allowing for manual positioning and shaping without causing tissue damage, by maintaining balanced forces and minimizing reaction to external forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If flexible surgical instruments are used to navigate convoluted paths, then the ability to reach target work sites is improved, but the stability and control of the device deteriorates due to unintended movements and springback reactions
Solution Approach 1:
The patent applies counterbalancing forces through spring systems that generate forces opposite to the springback reactions of flexible segments. These springs are configured to neutralize the elastic recovery forces when segments articulate or bend, preventing unintended movements and maintaining stable positioning at the target site.
Solution Approach 2:
The patent changes the mechanical parameters of the flexible instrument by introducing variable stiffness characteristics through spring systems. The ability to adjust tension and damping parameters allows the device to maintain flexibility for navigation while providing stability during instrument manipulation, effectively decoupling these two opposing requirements.
2Ease of operation
If cables or tendons are used to actuate mechanical features, then the control capability is improved, but the reaction forces and moment arms increase, potentially damaging adjacent tissue
Solution Approach 1:
The patent introduces spring systems as intermediary elements between the tendon actuators and the mechanical features. These springs act as force mediators that decouple the high-tension tendon forces from the direct transmission to tissue-contacting components, reducing the harmful reaction forces and moment arms while preserving actuation capability.
Solution Approach 2:
The spring systems are pre-configured to cushion and absorb excess forces before they can be transmitted to adjacent tissue. By providing compliant elements in advance, the system prevents the transmission of damaging peak forces that would otherwise occur during tendon actuation, especially during insertion and manipulation phases.
3Object-affected harmful factors
If the entry guide is made flexible to follow natural lumens, then the minimally invasive capability is improved, but the ability to provide a stable base for instrument manipulation deteriorates
Solution Approach 1:
The patent divides the entry guide into multiple articulated flexible segments that can independently bend and articulate. This segmentation allows the distal portions to flex and follow natural lumens for minimally invasive access, while the proximal segments maintain relative stability to provide a secure base for instrument manipulation, effectively distributing flexibility where needed while preserving stability where required.
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 solution enables the surgical device to respond to external forces without rapid springback, reducing the risk of tissue damage during procedures and allowing for precise manual or robotic control of the device's shape and position.
Implementation Method 1
a constant force spring system attached to the tendon
Implementation Method 2
an asymmetric spring system attached to the tendon
Data Source
Figure 1~2A
Figure 2B~3
AI summary
A compliant surgical device such as a flexible entry guide employs tendons to operate or steer the device and attaches asymmetric or constant force spring systems to control tension in the tendons. As a result, the surgical device can be compliant and respond to external forces during a surgical procedure without rapidly springing back or otherwise causing a reaction that damages tissue. The compliance also permits manual positioning or shaping of the device during or before insertion for a surgical procedure without damaging the tendons or connections of the tendons within the device or to a backend mechanism.