Steerable Tool Transmission for Stable Omnidirectional Tip Rotation
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Solution Overview
Problem
Current steerable surgical instruments face challenges with reduced dexterity due to the fulcrum effect and lack of wrist-like movements, leading to instability and difficulty in performing complex procedures, especially in minimally invasive surgeries where rotational stability and omnidirectional movement are crucial.
Innovation Solution
A mechanical transmission system (MTS) for steerable tools that includes a plurality of longitudinally arranged longitudinal members with anisotropic area moments of inertia, constrained at specific points to enhance rotational stability and prevent the spiral kinematic chain effect, allowing for omnidirectional movement and rotational freedom at the instrument tip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If omni-directional articulated instruments are used to provide wrist-like movements, then dexterity and maneuverability are improved, but tip stability decreases significantly
Solution Approach 1:
The patent implements a dynamic stabilization system where the counter-rotating mechanism automatically adjusts to maintain tip stability. When the instrument wrist bends, the first and second articulated sections rotate in opposite directions, dynamically compensating for rotational displacement and maintaining tip stability throughout the range of motion.
Solution Approach 2:
The patent changes the rotational parameter by implementing counter-rotation of the articulated sections. The first articulated section rotates in one direction while the second articulated section rotates in the opposite direction, effectively canceling out rotational displacement and maintaining tip orientation stability.
2Adaptability or versatility
If the number of articulated sections is increased to enable omni-directional movement, then degrees of freedom are improved, but mechanical complexity increases
Solution Approach 1:
The patent employs asymmetric articulation where the first and second articulated sections have different rotation axes and movement characteristics. This asymmetric design enables omni-directional movement while maintaining a relatively simple mechanical structure by avoiding symmetric redundancy.
Solution Approach 2:
The patent divides the instrument into segmented articulated sections (first articulated section and second articulated section) that can move independently. This segmentation allows each section to contribute specific degrees of freedom while keeping individual section complexity low.
3Stability of the object's composition
If rotational constraint is applied to longitudinal members to prevent spiral kinematic chain effect, then rotational stability is improved, but omnidirectional movement capability is reduced
Solution Approach 1:
The patent implements dynamic rotational constraint where the degree of rotational restriction varies along the length of the longitudinal members. The proximal portion has higher rotational constraint for stability, while the distal portion has lower constraint to allow omnidirectional tip movement.
Solution Approach 2:
The patent applies different rotational constraints to different portions of the longitudinal members. The proximal portion is more rotationally constrained to prevent spiral kinematic chain effect, while the distal portion allows greater freedom for omnidirectional movement.
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 MTS provides improved rotational stability and omnidirectional movement, reducing backlash and maintaining tip stability even in bent positions, enhancing the dexterity and maneuverability of steerable surgical instruments while minimizing invasiveness.
Implementation Method 1
a plane section of at least one longitudinal member (110) demonstrates an anisotropic area moment of inertia
Implementation Method 2
The majority of the longitudinal members (110) are each axially rotationally constrained at one or more constraining points along the bendable distal part (130) or along the shaft region (132)
Data Source
AI summary
Disclosed is a steerable tool with proximal and distal ends comprising a mechanical transmission system (MTS), shaft region, omnidirectionally moveable bendable proximal part (BPP), and omnidirectionally moveable bendable distal part responsive to movement of the BPP, where the MTS comprises longitudinal members (LM) each having proximal and distal ends, arranged in a longitudinal direction around a fictive tube, and has a corresponding transmission shaft region (TSR), transmission bendable proximal part (TBPP) and transmission bendable distal part (TBDP), wherein a plane section of at least one LM has an anisotropic area moment of inertia, and the majority of the LMs are axially rotationally constrained at one or more constraining points along the TBDP or TSR, the LMs are longitudinally slidable with respect to each constraining point, and the MTS is configured such that the TBDP tip is axially rotatable in a bent position by a complementary rotation of the TBPP.