Helical Joint Rolling Contacts for Surgical Instrument Bending
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Solution Overview
Problem
Current resiliently deformable joints for surgical instruments in minimal invasive surgery face challenges such as stress concentration, fatigue, and assembly difficulties due to material properties and design complexities, particularly in bending joints, while rigid joints introduce friction and backlash issues.
Innovation Solution
A helical structure with integrally formed body portions and rolling joints, where the helical structure distributes stress uniformly and the rolling joints provide controlled bending, allowing for precise manipulation and reduced friction, with guides for tendon routing to facilitate bending control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If bending joints with material elasticity are used, then the joint can achieve smooth bending, but stress concentration occurs in corner areas leading to fatigue and plastic deformation
Solution Approach 1:
The bending joint is segmented into multiple rigid tubular segments connected by articulation joints, distributing the bending stress across multiple discrete connection points rather than concentrating it in corner areas of a continuous structure
Solution Approach 2:
The invention changes the material parameter selection by using materials with appropriate mechanical properties for rigid segments, and controls the geometric parameters of the articulation joints to achieve desired bending characteristics without stress concentration
2Ease of manufacture
If rigid joints with rolling and hinge connections are used, then assembly is easier and tendon channels are easier to create, but friction and backlash are introduced reducing positioning accuracy
Solution Approach 1:
The invention optimizes the geometric parameters of the articulation joints, including the curvature radius and contact surface dimensions, to minimize friction and backlash effects while maintaining ease of manufacture and assembly
3Ease of operation
If tendon-driven compliant mechanisms are used, then the joint can be controlled via tendons, but the design depends on precise material properties and dimensions that are difficult to manufacture
Solution Approach 1:
The continuous compliant structure is segmented into discrete rigid segments with defined articulation joints, allowing traditional manufacturing methods to be used while maintaining tendon-driven control capability
Solution Approach 2:
Different parts of the structure have different properties: rigid tubular segments provide structural integrity and easy manufacturing, while articulation joints provide controlled flexibility and tendon response, with each part optimized for its specific function
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 helical structure with rolling joints offers improved torsional stiffness and reduced axial and bending stiffness, enabling precise and controlled bending with uniform stress distribution, overcoming the limitations of existing designs by enhancing flexibility and reducing friction-related inaccuracies.
Implementation Method 1
The resiliently deformable joint comprises a helical structure comprising a plurality of integrally formed body portions... The helical structure distributes stress uniformly
Implementation Method 2
each of which body joint components is formed on a respective body portion such that adjacent body joint components are abuttable with one another to form a body joint comprising a rolling joint
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A resiliently deformable joint (2) having a proximal end (4), a distal end (6) and an axis (8), the resiliently deformable joint comprising a helical structure (12) comprising a plurality of integrally formed body portions (10), each of which body portions comprising a turn of the helical structure and being moveable relative to adjacent body portions, the resiliently deformable joint further comprising a plurality of body joint components (14), each of which body joint components is formed on a respective body portion such that adjacent body joint components are abuttable with one another to form a body joint, the resiliently deformable joint further comprising first and second guides (22, 24) extending axially from the distal end to the proximal end of the resiliently deformable joint.