Deformable Drive Roller Notch for Catheter Traction
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Solution Overview
Problem
Existing drive rollers for advancing and retracting cylindrical objects, such as catheters, face challenges in achieving sufficient traction while minimizing the risk of damaging the object, due to limited working length and potential for local overstress.
Innovation Solution
The drive roller design incorporates a core member surrounded by a deformable member with an open notch, which deforms to capture the cylindrical object, and an elastic outer member with a toothed surface to enhance traction and minimize local forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If multiple rollers are used to minimize local pressure on the cylindrical object, then the pressure distribution is improved, but the contact length increases which limits the available working length of the cylindrical object
Solution Approach 1:
The drive roller is segmented into multiple functional layers: a core member, a deformable member with variable rigidity, and an elastic outer member. This segmentation allows each layer to contribute differently to the overall function, enabling pressure distribution across the contact surface while maintaining a compact contact length that preserves working length of the cylindrical object.
Solution Approach 2:
The deformable member has variable rigidity distributed locally across its structure, with different regions having different stiffness properties. This allows the roller to provide softer contact at certain locations and firmer support at others, optimizing pressure distribution without increasing overall contact length.
2Force
If the contact surface between drive roller and cylindrical object is increased to improve traction, then the friction force is improved, but the local force concentration may increase causing damage to the cylindrical object
Solution Approach 1:
The rigidity parameter of the deformable member is varied across its structure to optimize the balance between traction force generation and stress distribution. By carefully controlling the spatial distribution of rigidity, the roller achieves high friction force for good traction while preventing localized stress concentrations that could damage the cylindrical object.
Solution Approach 2:
The drive roller uses a composite structure combining materials with different mechanical properties - the core member, deformable member with variable rigidity, and elastic outer member. This composite construction enables the roller to simultaneously provide high traction through increased contact surface area and minimize local overstress through the compliant, stress-distributing properties of the deformable and elastic layers.
3Force
If a deformable member with variable rigidity is used to improve traction and distribute forces, then the contact surface is improved, but the device complexity increases
Solution Approach 1:
The drive roller employs a nested structure where the deformable member with variable rigidity is positioned between the core member and the elastic outer member. This nested arrangement allows the complex functionality of variable rigidity control to be integrated within a compact, multi-layered structure that does not significantly increase the overall device footprint or operational complexity.
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
This design achieves better traction forces with minimized local stress on the cylindrical object, allowing for effective advancement and retraction, even with small-diameter objects, while maintaining compact dimensions for the drive roller assembly and robotic apparatus.
Implementation Method 1
The deformable member comprises design and/or material properties causing a deformation of a lateral surface of the notch when the tubular object is pushed against a bottom surface of the notch
Implementation Method 2
The friction force between the cylindrical object and the roller is increased due to the increased contact surface and the resulting normal contact force
Data Source
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AI summary
The invention relates to a drive roller 2 for advancing and/or retracting a cylindrical object 104. The drive roller 2 comprises a core member 6 and a deformable member 8 radially surrounding the core member 6. The deformable member 8 comprises an outer peripheral surface 10. The outer peripheral surface 10 comprises an open notch 12, the open notch 12 being configured to receive the cylindrical object 104 therein. Thereby, the open notch 12 is deformed when the cylindrical object 104 is pushed against a bottom surface of the open notch 12 such that the cylindrical object 104 is better captured by the drive roller 2. As a consequence, very good traction forces are generated by such drive roller 2 while the overall dimensions of a corresponding drive roller assembly 200 or even robotic apparatus 300 are small.