Constant-Force Spring Retraction for Surgical Knife Safety
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Solution Overview
Problem
Robotic surgical systems face challenges in safely retracting cutting instruments, such as knives, during system failures or maintenance, due to the complexity of controlling the knife's position within the guide track.
Innovation Solution
The implementation of a retraction mechanism utilizing constant-force springs that bias the capstan assembly to a 'zero' or 'home' position, ensuring the knife is safely retracted and maintained in a secure position during system failures or maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a robotic system uses control algorithms to control the knife position, then the cutting precision is improved, but the system reliability deteriorates due to potential power loss or system failure
Solution Approach 1:
The spring mechanism is pre-loaded during normal operation to store potential energy. When power is lost or system failure occurs, this pre-stored energy automatically activates to retract the knife, ensuring safe bailout without requiring active control power.
Solution Approach 2:
The spring-loaded mechanism provides automatic self-service retraction capability. The system serves itself by using the stored mechanical energy to return the knife to the retracted position without requiring external power, control algorithms, or manual intervention during failure conditions.
2Device complexity
If the knife is left exposed after system failure, then the device complexity is reduced, but harmful factors increase due to safety hazards during cleaning and maintenance
Solution Approach 1:
The spring mechanism is pre-loaded during normal operation to store potential energy. When power is lost or system failure occurs, this pre-stored energy automatically activates to retract the knife, ensuring safe bailout without requiring active control power.
Solution Approach 2:
The spring-loaded mechanism provides automatic self-service retraction capability. The system serves itself by using the stored mechanical energy to return the knife to the retracted position without requiring external power, control algorithms, or manual intervention during failure conditions.
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 effectively ensures the knife is safely retracted, reducing hazards during cleaning and maintenance, and maintaining accuracy and precision in the surgical tool's operation.
Implementation Method 1
at least one biasing member mounted to the drive housing and operatively coupled to at least one of the capstan assembly and the longitudinally driven gear to bias the longitudinally driven gear toward the proximal position with a constant force
Data Source
AI summary
A surgical tool includes a drive housing, a drive input rotatably mounted to a bottom of the drive housing, a capstan assembly arranged within the drive housing and operatively coupled to the drive input such that rotation of the drive input correspondingly actuates the capstan assembly, a longitudinally driven gear engageable with the drive gear, a drive rod coupled to the longitudinally driven gear and extending from the drive housing to an end effector of the surgical instrument and at least one biasing member mounted to the drive housing and operatively coupled to at least one of the capstan assembly and the longitudinally driven gear. The biasing member biases the longitudinally driven gear toward a proximal position with a constant force.