Drive Cable Capstan Pulley Track for Robotic Surgical Tools
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Solution Overview
Problem
Robotic surgical systems face challenges with cable derailment and the need for idler pulleys, which increase part count, weight, and complexity, while existing designs often require drive cables to wrap around multiple locations, increasing the risk of derailment and assembly difficulties.
Innovation Solution
The implementation of a rotatable drive cable capstan with a single plane pulley track, where the drive cable wraps only partially around the capstan and is fed directly into an elongate shaft, eliminating the need for idler pulleys and reducing the risk of cable derailment by limiting it to a single location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If drive cables wrap around multiple locations on the capstan, then the cable can be secured more firmly, but the risk of cable derailment increases and assembly becomes more difficult
Solution Approach 1:
The capstan surface is segmented into multiple pulley tracks, each capable of receiving and guiding the drive cable independently. This segmentation allows the cable to be routed through multiple defined paths without increasing derailment risk, as each track acts as an independent containment structure.
Solution Approach 2:
The pulley track acts as an intermediary structure between the capstan and the drive cable. It provides a defined pathway that mediates the interaction between the rotating capstan and the cable, preventing direct contact that could lead to derailment while maintaining secure cable engagement.
2Ease of operation
If idler pulleys are added to the system, then cable routing can be improved, but the part count, weight, and device complexity increase
Solution Approach 1:
The pulley track is merged with the capstan structure itself, forming an integrated component rather than separate idler pulleys. This combination eliminates the need for additional standalone pulley components while maintaining the cable routing functionality, thereby reducing part count and device complexity.
Solution Approach 2:
The capstan serves multiple functions: it provides the driving rotation, defines the pulley track for cable routing, and acts as the structural element that would traditionally require separate idler pulleys. This multi-functionality eliminates the need for additional dedicated cable routing components.
3Adaptability or versatility
If drive cables extend through the wrist joint, then the end effector can be articulated, but the risk of cable derailment and assembly difficulty increase
Solution Approach 1:
The pulley track is pre-defined on the capstan during manufacturing, creating a predetermined cable pathway before assembly. This preliminary structuring of the cable route simplifies the assembly process, as the cable can be directly routed through the pre-formed track without requiring complex alignment or additional routing components.
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 mitigates cable derailment risks, reduces part count and weight, simplifies assembly, and maintains efficient cable movement within the robotic surgical system, enhancing the reliability and precision of robotic surgical tools.
Implementation Method 1
a drive cable is received within a pulley track defined on the drive cable capstan and extending only partially around a circumference of the drive cable capstan
Implementation Method 2
the drive cable is fed directly into an elongate shaft from the pulley track
Data Source
AI summary
A surgical tool includes a drive housing having an input shaft and a drive cable capstan arranged therein. The input shaft includes a drive gear and the drive cable capstan including a driven gear intermeshed with the drive gear such that rotation of the input shaft rotates the drive cable capstan. An elongate shaft extends from the drive housing, and an end effector is operatively coupled to a distal end of the elongate shaft. A drive cable is received within a pulley track defined on the drive cable capstan and extends only partially around a circumference of the drive cable capstan. The drive cable is fed directly into the elongate shaft from the pulley track and extends to the end effector.