Dynamic Preload Tensioners for Surgical Instrument Cable Control
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Solution Overview
Problem
Surgical instruments with slack or low tension in cables experience jumpy or unpredictable motion of the end effector, and high preload tension increases friction and operational forces, necessitating a solution to maintain consistent cable tension.
Innovation Solution
A surgical instrument with a dynamic preload tensioner that adjusts the path of flexible tensioning elements using drive components, allowing for controlled tension adjustment and reduced friction, even as the instrument ages or experiences material changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high preload tension is applied to flexible tensioning elements, then cable tension consistency is improved, but friction and operational forces increase
Solution Approach 1:
The patent implements a dynamic tensioning system that actively adjusts cable tension during operation. Sensors monitor tension levels and a control system actuates tensioning mechanisms to maintain optimal tension, transitioning from static high preload to dynamic adaptive tensioning. This resolves the contradiction by maintaining consistency without permanently high force levels.
Solution Approach 2:
The system changes the tension parameter dynamically based on operational conditions. By monitoring cable deflection, sensor readings, and actuator position, the system adjusts tension levels in real-time, allowing low tension during positioning and higher tension during cutting operations, thus avoiding continuously high operational forces.
2Reliability
If high preload tension is applied to flexible tensioning elements, then cable tension consistency is improved, but friction at contact surfaces increases
Solution Approach 1:
The dynamic tensioning system adjusts friction levels dynamically. During low-load operations, tension is reduced to minimize friction at cable-pulley and cable-guide surface contacts. During high-load cutting operations, tension is increased to maintain cable tightness. This temporal separation resolves the contradiction between tension consistency and friction reduction.
Solution Approach 2:
The patent replaces passive mechanical friction-based tension maintenance with an active control system using sensors and actuators. This substitution allows precise tension management that minimizes friction losses while maintaining cable consistency, overcoming the limitations of purely mechanical preload systems.
3Reliability
If static preload tension is maintained throughout instrument design life, then cable tension consistency is improved, but adaptability to material changes deteriorates
Solution Approach 1:
The system transitions from static preload to dynamic adaptive tensioning. As cable materials age and undergo creep or stress relaxation, the dynamic system continuously monitors tension levels and adjusts actuator positions to compensate. This maintains consistent tension throughout the instrument's design life while adapting to material property changes.
Solution Approach 2:
The patent implements feedback control where sensors monitor cable tension, deflection, and actuator position continuously. This feedback information is processed by a control system that adjusts tensioning in real-time, enabling the system to adapt to material changes and maintain consistency throughout the instrument's operational life.
4Reliability
If dynamic preload tensioner is added to adjust cable path, then tension consistency is improved, but device complexity increases
Solution Approach 1:
The dynamic tensioning mechanism serves multiple functions: it maintains cable tension, compensates for material creep, adapts to different operational phases, and compensates for manufacturing tolerances. By consolidating these functions into a single integrated system, the patent reduces overall device complexity compared to having separate mechanisms for each function.
Solution Approach 2:
The system performs self-adjustment through automated sensor monitoring and control actuation. The tensioning mechanism monitors its own performance and automatically compensates for deviations, reducing the need for external intervention and simplifying the overall control architecture. This self-service capability justifies the added complexity by eliminating manual adjustment mechanisms.
Data Source
AI summary
A surgical system includes a dynamic preload tension feature for a tensioning element that actuates a distal end component of a surgical instrument. The surgical instrument includes a chassis at a proximal end of the surgical instrument, drive components mounted in the chassis, a distal end component at a distal end of the surgical instrument, a flexible tensioning element coupled between a first of the drive components and the distal end component, and a dynamic preload tensioner mounted in the chassis and coupled to a second of the drive components. The flexible tensioning element extends along a path. The dynamic preload tensioner is configured to be driven by the second of the drive components to be moved relative to the chassis and is positioned to change the path of the flexible tensioning element as the dynamic preload tensioner moves relative to the chassis.