Articulable Wrist Roller Supports Prevent Cable Tip Dive
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Solution Overview
Problem
In robotic surgical systems, the articulation of cables through the wrist joint can cause undesirable tip deflection or 'tip dive' when clamping tissue due to off-center positional offsets, leading to unbalanced moments and abrupt jaw movement, which is undesirable in surgical procedures.
Innovation Solution
The implementation of laterally offset roller supports at articulation joints to prevent closure and open cables from deviating below the pivot axis, thereby maintaining cable balance and reducing tip dive during jaw clamping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If cables are routed through the flexible member and articulation joints without constraint, then the system achieves simpler cable routing and fewer components, but cable pathways dip below the pivot axis during articulation causing tip dive
Solution Approach 1:
Roller supports are introduced as intermediary components between the cables and the articulation joint pivot axis. These rollers constrain the cables to remain centered on the pivot axis during articulation, preventing the cables from dipping below the axis and eliminating the unbalanced moment that causes tip dive.
2Reliability
If roller supports are added to constrain cables, then cable balance is maintained and tip dive is reduced, but device complexity increases
Solution Approach 1:
Rather than redesigning the entire cable routing system, roller supports are applied locally at the articulation joints where the problem occurs. This localized approach provides the necessary constraint to prevent tip dive while minimizing the overall increase in device complexity.
Data Source
AI summary
An articulable wrist for an end effector includes a first linkage rotatably coupled to a second linkage at a first articulation joint, a flexible member extending at least partially through a central channel cooperatively defined by the first and second linkages, and a first pair of roller supports arranged at the first articulation joint and laterally offset from each other, each roller support extending parallel to a first pivot axis extending through the first articulation joint. A drive cable extends through a first axially-extending conduit defined in the flexible member and through a gap defined between the first pair of roller supports. The drive cable is supported at the first articulation joint by the first pair of roller supports during articulation and the first pair of roller supports prevents a centerline of the drive cable from moving past the first pivot axis during actuation of the end effector.