Asymmetric Sector Gear Decoupling for Robotic Surgical Shaft Translation
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Solution Overview
Problem
Current robotic surgical systems face challenges in efficiently translating and firing mechanisms, particularly in minimally invasive procedures, where precise control and flexibility are crucial for end effectors like knives and staplers, often requiring complex actuation systems that can decouple and recouple to allow for both z-axis translation and end effector operation.
Innovation Solution
The integration of a rack-based translation and firing transmission system with asymmetric gears, where a sector gear with a tooth-free zone allows for decoupling and recoupling, enabling the shaft to move freely in z-axis translation while engaging with the rack to drive the end effector, such as a knife, using a drive mechanism with beveled gears and spools to manage cable tension for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rack-based translation and firing transmission system is used, then the precision of end effector operation is improved, but the complexity of the actuation system increases
Solution Approach 1:
The sector gear is designed with a tooth-free zone that allows it to dynamically transition between engaged and disengaged states with the rack. This dynamic capability enables the system to switch between translation mode (tooth-free zone facing rack) and firing mode (teeth engaged with rack), reducing the need for separate actuation systems and simplifying overall system complexity while maintaining precision control
2Ease of operation
If the shaft is decoupled from the actuation system to allow free z-axis translation, then the ease of operation is improved, but the control precision deteriorates
Solution Approach 1:
The sector gear's rotational position determines whether the shaft is coupled or decoupled from the firing actuation system. When the tooth-free zone faces the rack, the shaft is decoupled allowing free z-axis translation controlled by the second actuation system. When teeth engage the rack, precise firing control is restored. This dynamic coupling/decoupling mechanism maintains both ease of operation and control precision at different operational stages
3Adaptability or versatility
If asymmetric gears with tooth-free zones are used, then the versatility of the transmission system is improved, but the manufacturing complexity increases
Solution Approach 1:
The sector gear is designed with asymmetric tooth distribution, creating a tooth-free zone that enables multiple functions from a single component. This asymmetric design allows the same gear to facilitate both translation (when disengaged) and firing (when engaged), increasing system versatility. The manufacturing complexity is managed by using standard gear manufacturing processes adapted to create the asymmetric pattern, rather than requiring entirely new manufacturing methods
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 solution enhances the precision and ease of use in robotic surgical tools by allowing seamless z-axis translation and end effector operation, improving the flexibility and control of surgical instruments during procedures, thereby facilitating more effective and intuitive minimally invasive surgeries.
Implementation Method 1
a sector gear engageable with the rack and including a tooth-free zone, and a second actuation system housed within the handle and operable to cause z-axis translation of the shaft through the handle
Implementation Method 2
the drive mechanism includes a beveled drive gear coupled to the drive shaft, and a beveled driven gear arranged to be driven by the beveled drive gear, wherein the sector gear is coupled to the beveled driven gear
Implementation Method 3
the second actuation system includes a spool operatively coupled to a drive input included in the handle such that actuation of the drive input rotates the spool, a first drive cable having a first end anchored to the shaft distal to the handle and a second end secured to the spool
Implementation Method 4
a rack-based translation and firing transmission system with asymmetric gears, where a sector gear with a tooth-free zone allows for decoupling and recoupling
Data Source
AI summary
A robotic surgical tool includes an elongate shaft extended through a handle and having an end effector arranged at a distal end thereof, a rack extending along a portion of the shaft and operatively coupled to a knife located at the end effector, a first actuation system housed within the handle and operable to drive the rack and thereby advance or retract the knife at the end effector, the first actuation system including a sector gear engageable with the rack and including a tooth-free zone, and a second actuation system housed within the handle and operable to cause z-axis translation of the shaft through the handle. Rotating the sector gear such that the tooth-free zone faces the rack decouples the shaft from the first actuation system to allow the shaft to freely move in z-axis translation.