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 actuating cables during manipulation of jaw members in surgical instruments, 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 cables by translating longitudinally to counteract manual forces applied to the jaw members, ensuring continuous tension and preventing slack.
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 installation, but the cables lose tension and become slack during manipulation of jaw members
Solution Approach 1:
The biasing element is pre-installed in the drive assembly to automatically apply tension to the cable before any surgical manipulation occurs. This preliminary action ensures the cable starts in a tensioned state and maintains tension throughout jaw member manipulation, preventing slack and dislodgment while preserving the flexible cable-based actuation system.
2Reliability
If the drive assembly uses a biasing element to maintain cable tension, then cable tension is maintained in passive state, but the device complexity increases
Solution Approach 1:
The biasing element is integrated into the existing drive assembly structure, combining the tension-maintenance function with the cable actuation mechanism. This merging approach maintains reliability by ensuring continuous cable tension while avoiding the need for separate, complex tensioning systems, thus minimizing additional device complexity.
3Reliability
If the follower is biased proximally by the biasing element, then cable tension is maintained during manual manipulation, but the manufacturing precision requirements increase
Solution Approach 1:
The follower is designed with dynamic positioning capability, allowing it to move proximally and distally along the drive screw while maintaining cable tension through the biasing element. This dynamic design accommodates manual manipulation of jaw members without requiring extremely tight manufacturing tolerances, as the system adapts to position changes while maintaining functional integrity.
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 maintains cable tension both in active and passive states, preventing slack and dislodgment, thereby enhancing the reliability and precision of robotic surgical systems by ensuring consistent mechanical force application during surgical procedures.
Implementation Method 1
the biasing element, typically a compression spring, maintains tension in the cables by translating longitudinally to counteract manual forces applied to the jaw members
Implementation Method 2
The drive nut is threadedly engaged with the threaded portion of the drive screw such that rotation of the drive screw results in longitudinal movement of the drive nut
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.