Steerable Endoscopic Instrument Play Reduction via Fracture Elements
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Solution Overview
Problem
Steerable instruments for endoscopic and invasive applications face challenges in achieving optimal performance due to excessive play between parts, which affects distal tip payloads, steering accuracy, repeatability, and durability, particularly when manufactured using techniques like laser cutting that introduce minimum play equal to or larger than the cutting beam width.
Innovation Solution
The solution involves managing play by creating a reduced-play state through specific cutting patterns and fracture elements in cylindrical elements, allowing for controlled deflection angles and longitudinal displacements, thereby minimizing tangential and radial play, and enhancing the instrument's maneuverability and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser cutting is used to manufacture cylindrical elements, then manufacturing precision is improved, but play between parts increases due to minimum play equal to or larger than the cutting beam width
Solution Approach 1:
The patent applies preliminary action by creating fracture elements during the laser cutting process itself, before the instrument is assembled and used. The fracture elements are intentionally left as thin bridges of material that will break during a preliminary bending operation, thereby pre-reducing the play between parts to values smaller than the laser beam width.
Solution Approach 2:
The patent segments the cylindrical element wall into multiple fracture elements that can independently break. This segmentation allows the play reduction to occur in a controlled manner across multiple discrete locations, ensuring comprehensive reduction of tangential and radial play throughout the instrument structure.
2Ease of manufacture
If conventional steering cables are used, then ease of manufacture is improved, but device complexity increases and steering accuracy deteriorates due to excessive play
Solution Approach 1:
The patent extracts the steering function from conventional cable-based steering arrangements and integrates it directly into the cylindrical element structure through fracture elements. This eliminates the need for separate steering cables, reducing device complexity while maintaining manufacturing ease, as the fracture elements are created during the same laser cutting process that manufactures the cylindrical elements.
3Reliability
If fracture elements are introduced to reduce play, then reliability is improved, but manufacturing complexity increases due to additional processing steps
Solution Approach 1:
The patent merges the fracture element creation process with the existing laser cutting manufacturing process. Instead of adding a separate manufacturing step, the fracture elements are created as part of the same laser cutting operation that manufactures the cylindrical elements, thereby improving reliability without significantly increasing manufacturing complexity.
4Measurement precision
If play is reduced through fracture elements, then steering accuracy is improved, but friction and hysteresis increase during operation
Solution Approach 1:
The patent applies dynamics by designing the fracture elements to break at a specific moment during instrument operation, transitioning the structure from a high-play state to a low-play state. This dynamic transformation allows the instrument to operate with minimal friction and hysteresis once the fracture elements have broken, while maintaining the ability to reduce play when needed.
Data Source
AI summary
A cylindrical instrument has a tube with a movable element (1677; 16(2)) and first further element (1675; 16(1); 16(3)). The movable element (1677; 16(2)) has a movable element extending portion (1603a; 1702a1; 2002b) adjacent to a movable element indented portion (1603b; 1702b1; 2002a/2002c). In a manufactured state the movable element extending portion (1603a; 1702a1; 2002b) is located opposite a first further element indented portion (1601b; 1701b; 2001b) at a first distance and the movable element indented portion (1603b; 1702b1; 2002a/2002c) is located opposite a first further element extending portion (1601a; 1701a; 1701c; 2001a/2001c) at a second distance. Relative sideways movement between the movable element (1677; 16(2)) and the first further element (1675; 16(1); 16(3)) is possible such that when the relative sideways movement is larger than a predetermined distance the movable element extending portion (1603a; 1702a1; 2002b) is opposite the first further element extending portion (1601a; 1701a; 1701c; 2001a/2001c) at a third distance which is smaller than the first distance.