Braided Articulation Assembly for Robotic Surgical Instruments
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Solution Overview
Problem
Robotic surgical systems face challenges in articulating elongate members without causing longitudinal compression and ensuring force isolation, which can lead to buckling or other undesired effects, while also requiring cost-effective manufacturing and maintaining cross-sectional efficiency.
Innovation Solution
The use of a braided structure with helically oriented stiffening wires and coaxial braids provides lateral flexibility, resists compression, and isolates forces to prevent buckling, while maintaining reduced manufacturing costs and cross-sectional efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional articulation mechanisms are used in elongate members, then articulation capability is achieved, but longitudinal compression and force isolation problems occur leading to buckling
Solution Approach 1:
The articulation assembly is segmented into multiple independent components: an inner braid with tendon lumens, an outer braid with stiffening wires, and articulation sections with articulation planes. This segmentation allows each component to perform its specific function (force transmission, structural support, articulation) while working together to prevent buckling and maintain reliability during articulation movements
Solution Approach 2:
The inner braid is nested within the outer braid, creating a concentric structure where the inner braid containing tendon lumens is positioned inside the outer braid containing stiffening wires. This nested configuration allows both braids to work together, with the inner braid transmitting articulation forces and the outer braid providing compression resistance, thereby preventing buckling while maintaining articulation capability
2Adaptability or versatility
If articulation assembly is added to enable flexibility, then lateral flexibility is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The braided structure serves multiple functions simultaneously: the inner braid transmits articulation forces, the outer braid provides compression resistance, the tendon lumens guide articulation tendons, and the stiffening wires prevent buckling. This multi-functionality reduces the need for separate components, thereby managing device complexity while achieving lateral flexibility
Solution Approach 2:
The braided construction uses flexible braid strands woven into a tubular structure that inherently provides both flexibility and structural support. The braided configuration allows lateral bending while maintaining longitudinal integrity, achieving lateral flexibility without requiring complex internal mechanisms that would increase device complexity
3Reliability
If braided structure with multiple components is used, then force isolation and compression resistance are improved, but manufacturing complexity increases
Solution Approach 1:
Multiple functional components (inner braid, outer braid, tendon lumens, stiffening wires) are merged into a single integrated braided assembly that can be manufactured as one unit. The braided structure is constructed by interweaving strands that simultaneously create all necessary components, achieving force isolation and compression resistance while simplifying manufacturing through a unified construction process
Solution Approach 2:
The articulation assembly uses composite construction combining different braid strands, tendon lumens, and stiffening wires into a unified structure. This composite approach allows each material to contribute its specific properties (flexibility, strength, compression resistance) while being manufactured together, achieving force isolation without proportionally increasing manufacturing complexity
4Reliability
If thicker wall structure is used to prevent buckling, then structural integrity is improved, but cross-sectional efficiency decreases
Solution Approach 1:
The outer braid provides localized compression resistance and buckling prevention where needed, while the inner braid handles force transmission. This local differentiation of structural qualities allows the structure to achieve structural integrity through targeted reinforcement rather than uniformly thickening the entire wall, thereby maintaining cross-sectional efficiency
Solution Approach 2:
Instead of increasing wall thickness in the radial dimension, the patent uses the braided configuration to provide structural support through the longitudinal and circumferential arrangement of braid strands. The stiffening wires in the outer braid are oriented to resist compression forces, providing structural integrity through dimensional optimization rather than simply increasing wall thickness, thus maintaining cross-sectional efficiency
Data Source
AI summary
An apparatus includes an elongate body, first and second tendons, and first and second stiffening members. The tendons extend through the elongate body and have respective distal ends that are fixedly secured relative to the distal end of the elongate body. The tendons are operable to drive articulation of the distal portion of the elongate body. The stiffening members have respective distal ends that are fixedly secured relative to the distal end of the elongate body. The first tendon and the first stiffening member are positioned adjacent to each other along the proximal portion; and are angularly offset from each other along the distal portion. The second tendon and the second stiffening member are positioned adjacent to each other along the proximal portion; and are angularly offset from each other along the distal portion.