Joint Mechanism with Decentered Turnaround for Reduced Traction
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Solution Overview
Problem
Existing multi-joint bending mechanisms require significant traction force and have limited controllability due to the routing of manipulation wires and guide sheaths, which affects the efficiency and precision of bending in medical devices like endoscopes.
Innovation Solution
A joint mechanism with a tubular first member, a swivelable second member, a flexible guide sheath, and a manipulation wire that makes a U-turn at a turnaround section decentered from the swivel axis, allowing for efficient bending with reduced traction force and improved controllability by maintaining the guide sheath's rigidity and minimizing friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If manipulation wires and guide sheaths are routed close to the outer periphery of bending segments, then bending efficiency is improved, but device size increases and controllability deteriorates
Solution Approach 1:
The manipulation wire is routed through the radial dimension by introducing it into the guide sheath and extending it to the outer periphery, rather than routing it along the longitudinal axis. This dimensional change allows the wire to achieve efficient bending leverage while maintaining a compact overall device structure.
Solution Approach 2:
The manipulation wire is nested within the guide sheath, with the wire extending from the distal end of the sheath to the outer periphery. This nested configuration allows both components to occupy the same spatial envelope, reducing overall device size while maintaining functional effectiveness.
2Device complexity
If manipulation wires are disposed at the inner side relative to outer manipulation wires, then structural organization is improved, but traction force requirements increase
Solution Approach 1:
The manipulation wire is pre-positioned and fixed at the outer periphery of the bending segment before actuation. This preliminary positioning ensures that the wire acts at the maximum lever arm distance from the swivel axis, optimizing bending efficiency and minimizing the traction force required during operation.
Data Source
AI summary
A manipulator including joint mechanisms each including: first and second members extending along a central axis; the second member disposed at a distal end of the first member and being swivelable relative to the first member about a swivel axis; a guide sheath extending near the central axis, a distal end of the guide sheath being fixed to the second member; a manipulation wire introduced toward the distal end of the guide sheath; and a pulley provided in the second member such that the manipulation wire is wound at least partially around the pulley to cause a distal end of the wire to change direction towards the first member, the pulley being rotatable about an axis parallel to the swivel axis; wherein the distal end of the manipulation wire is fixed to the first member near the inner surface of the through hole.