Cable Actuation for Robotic Surgical Tool Articulation
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Solution Overview
Problem
Current robotic surgical tools face challenges in efficiently articulating end effectors due to limitations in cable-based actuation systems, which hinder precise movement and control during minimally invasive procedures.
Innovation Solution
A robotic surgical tool with a proximally mounted, cable-based actuation system that includes a rocker bar mechanism and lead screw system, allowing for antagonistic movement of drive cables to articulate the end effector, enhancing precision and control through a combination of pulleys and idler pulleys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a cable-based actuation system is used to articulate the end effector, then the surgical tool can be miniaturized for minimally invasive procedures, but the precision and control of end effector articulation deteriorates
Solution Approach 1:
The actuation system is divided into multiple independent cable segments (first drive cable and second drive cable) that can be controlled separately. Each cable operates through its own pulley system and idler pulleys, allowing independent adjustment of each cable's tension and position. This segmentation enables precise control of the rocker bar articulation despite the miniaturized shaft length.
Solution Approach 2:
Idler pulleys are introduced as intermediary components between the drive cables and the rocker bar system. These idler pulleys (first idler pulley and second idler pulley) modify the cable paths, providing mechanical advantage and precise tension control. The idler pulleys act as mediators that translate the drive cable movements into precise rocker bar articulation, overcoming the limitations of short shaft length.
2Ease of operation
If a rocker bar system with multiple drive cables is used to articulate the end effector, then the ease of operation improves, but the device complexity increases
Solution Approach 1:
The handle assembly serves multiple functions: it houses the actuation system, provides the drive inputs for both cables, contains the pulley system, and supports the rocker bar mechanism. This multi-functionality reduces the need for separate components, thereby managing complexity while maintaining ease of operation through integrated design.
Solution Approach 2:
The actuation system is designed to be self-regulating through the interplay of the two drive cables and idler pulleys. When one cable is tightened, the system automatically adjusts the other cable's tension through the rocker bar mechanism, providing self-balancing control that simplifies operation despite the multi-component system.
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 solution enables improved articulation and control of end effectors, facilitating more precise and intuitive surgical procedures by effectively translating drive inputs into antagonistic movements of the rocker bar system, thereby enhancing the capability of robotic surgical tools in minimally invasive surgeries.
Implementation Method 1
a lead screw extending from the drive input and rotatable therewith, a nut threadably mounted to the lead screw such that rotation of the lead screw causes the nut to traverse the lead screw
Implementation Method 2
a first pulley rotatably mounted to an armature extending laterally from the nut, a second pulley rotatably coupled to the handle and axially offset from the first pulley, wherein movement of the nut along the lead screw moves the first pulley toward or away from the second pulley
Implementation Method 3
a rocker bar system arranged at a proximal end of the shaft and actuatable to articulate an end effector at a distal end of the shaft
Data Source
AI summary
A robotic surgical tool includes an elongate shaft extendable through a handle that provides a drive input, an actuation system housed within the handle and operatively coupled to the drive input such that actuation of the drive input operates the actuation system, a rocker bar system arranged at a proximal end of the shaft and actuatable to articulate an end effector at a distal end of the shaft, and first and second drive cables extending along a portion of the shaft, each drive cable having a proximal end anchored to the shaft proximal to the handle and a distal end anchored to the shaft distal to the handle, wherein the drive cables are threaded through portions of the actuation and rocker bar systems such that operation of the actuation system acts on the drive cables and thereby actuates the rocker bar system to articulate the end effector.