Surgical End Effector Pulley Cable Actuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Robotic surgical systems require precise control of end effectors to grasp and dissect tissue, but existing systems lack the necessary fine control for deep tissue access, particularly in terms of force application by the jaws of surgical tools.
Innovation Solution
A pulley assembly system with driven pulleys and cables is used to control the jaws of surgical tools, where rotating a driving pulley in one direction opens the jaws and in the opposite direction closes them, utilizing tensioned and slackened cables to achieve precise movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple cable-pulley system is used to actuate end effector jaws, then the device complexity is reduced, but the precision of force control deteriorates
Solution Approach 1:
The pulley assembly is segmented into multiple independent pulleys (first pulley, second pulley, third pulley, fourth pulley) rather than using a single integrated mechanism. Each pulley handles specific cable routing functions, allowing the system to maintain mechanical simplicity while achieving precise force control through coordinated cable tension management across multiple discrete components.
Solution Approach 2:
Cables serve as intermediaries that transmit force from the actuation mechanism to the end effector jaws. The cable-pulley system acts as a mediator that transforms rotational motion into precise linear force application, enabling fine control of jaw closure forces without requiring direct mechanical connection between the actuator and the jaws.
2Ease of operation
If cables are tensioned and slackened to control jaw movement, then the ease of operation is improved, but the reliability deteriorates due to potential cable slack and play
Solution Approach 1:
The cable tension system dynamically adjusts between tensioned and slackened states to control jaw movement. During jaw closure, cables are tensioned to transmit actuation force; during jaw opening, cables are allowed to slacken. This dynamic tension management enables easy bidirectional jaw actuation while maintaining reliable force transmission during the critical closure phase through proper timing of cable engagement.
Solution Approach 2:
The cable system operates in periodic cycles of tensioning and slackening corresponding to the jaw closure and opening phases. This periodic action allows the system to reset cable tension regularly, preventing cumulative slack buildup and maintaining reliable force transmission during each jaw closure cycle while keeping the operation simple and intuitive.
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 system allows for precise control of the jaws, enabling effective grasping and dissecting of tissue, enhancing the capability for deep tissue access during minimally invasive procedures.
Implementation Method 1
The cables connected to a pulley assembly that transferred torque to drive the actuation of the end effector
Implementation Method 2
A pulley assembly including pulleys and cables... rotating a driving pulley... The first and second driven pulleys may be rotated via the first cable responsive to rotating the driving pulley
Implementation Method 3
The first cable may be tensioned and the second cable may be slackened during rotation of the driving pulley in the first direction
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
An end effector of a surgical tool includes a first jaw and a second jaw rotated by a driving pulley. A first driven pulley is attached to the first jaw and a second driven pulley is attached to the second jaw. A first end portion of a first cable is connected to a first radial side of the first driven pulley, a second end portion of the first cable is connected to a second radial side of the second driven pulley, and an intermediate portion of the first cable is connected to the driving pulley. A first end portion of a second cable is connected to a first radial side of the second driven pulley, a second end portion of the second cable is connected to a second radial side of the first driven pulley, and an intermediate portion of the second cable is connected to the driving pulley.