Surgical Instrument Drive Assembly for Cable Tension Maintenance
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Solution Overview
Problem
Robotic surgical systems face issues with cable slack due to loss of tension in instrument drive units during manipulation of jaw members, leading to potential dislodgment and inefficiency in surgical procedures.
Innovation Solution
The instrument drive unit incorporates a drive assembly with a drive screw, drive nut, follower, biasing element, and flexible drive element, where the biasing element, typically a compression spring, maintains tension in the flexible drive element through mechanical cooperation, preventing slack and ensuring consistent operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If cables are used to actuate surgical instrument functions, then the system achieves flexibility and ease of operation, but the cables lose tension and become slack during manipulation
Solution Approach 1:
A follower component is introduced as an intermediary element that mediates between the cable and the jaw members. The follower maintains continuous contact with both the cable and the jaw members, ensuring that cable movements are always transmitted effectively to the instrument functions without loss of tension or control.
Solution Approach 2:
The system uses the existing cable tension and mechanical movements to automatically maintain proper tension through the follower mechanism. As the jaw members move, the follower passively maintains contact and tension without requiring external active control systems.
2Reliability
If the instrument drive unit maintains constant tension in cables, then reliability improves, but device complexity increases
Solution Approach 1:
The follower mechanism automatically maintains cable tension through passive mechanical interaction with the moving jaw members. The system self-regulates tension based on the natural movements of the instrument, eliminating the need for external active tension control systems.
Solution Approach 2:
The follower is designed as a simple, inexpensive mechanical component that can be easily manufactured and replaced if needed. This simple mechanical solution avoids complex electronic or motorized tension control systems.
3Reliability
If the follower is disposed distally of the drive nut, then cable tension is maintained, but the drive assembly complexity increases
Solution Approach 1:
The follower acts as an intermediary component positioned between the drive nut and the jaw members. It mediates the force transmission from the drive mechanism to the cable, ensuring continuous tension maintenance while adding minimal structural complexity to the overall assembly.
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 configuration maintains tension in the drive elements during both active and passive states, preventing cable slack and ensuring reliable operation of surgical instruments, thereby enhancing the precision and effectiveness of robotic surgical systems.
Implementation Method 1
The biasing element is a compression spring
Implementation Method 2
The biasing element is disposed in mechanical cooperation with the drive nut and the follower
Data Source
AI summary
A drive assembly of an instrument drive unit, is provided. The drive assembly includes a drive screw, a drive nut, a follower, a biasing element, and a drive element. The drive nut is threadedly engaged with a threaded portion of the drive screw such that rotation of the drive screw results in longitudinal movement of the drive nut. The follower is longitudinally slidable with respect to the drive screw. The biasing element is disposed in mechanical cooperation with the drive nut and the follower. The drive element is disposed in mechanical cooperation with the follower. Longitudinal translation of the drive element is configured to drive a function of the surgical instrument.