Surgical Instrument Steering Input Device With Self-Locking Friction Coupling
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Solution Overview
Problem
Conventional mechanically actuated surgical instruments with steering input devices are expensive to produce due to intricate components that require precise machining, and their assembly and pre-tensioning processes are cumbersome and difficult to automate.
Innovation Solution
A surgical instrument with an adjustable end effector and a drive assembly featuring a housing, an input device with a drive shaft and capstan, and a drive cable extending along the instrument shaft. The input device includes a radially tapered outer surface on the drive shaft and a radially tapered inner surface on the capstan, allowing for a self-locking frictional coupling that facilitates controlled adjustment of the end effector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mechanically actuated surgical instruments with intricate components are used, then precise control and high torque capability are achieved, but manufacturing cost increases and device complexity increases
Solution Approach 1:
The drive shaft is segmented into multiple independent cable channels, allowing each cable to be tensioned and adjusted separately. This segmentation simplifies the overall assembly process while maintaining precise control over each individual cable's tension, resolving the contradiction between precise control and device complexity.
Solution Approach 2:
The patent extracts the tensioning function from complex mechanical assemblies and implements it through simple friction-based interfaces between the drive shaft and cables. By taking out the intricate pre-tensioning mechanisms and replacing them with straightforward frictional engagement, the device achieves precise control with reduced complexity.
2Force
If conventional mechanically actuated surgical instruments with multiple intricate components are used, then high torque capability is achieved, but manufacturing cost increases
Solution Approach 1:
The drive shaft design allows cables to be tensioned and secured through self-service frictional engagement without requiring external pre-tensioning equipment or complex assembly procedures. The friction between the drive shaft surface and cable creates automatic self-locking, eliminating the need for intricate pre-tensioning mechanisms and reducing manufacturing costs while maintaining high torque capability.
Solution Approach 2:
The patent replaces expensive, intricately machined pre-tensioning mechanisms with simple, easily manufactured friction-based interfaces. The drive shaft uses basic geometric features (flat surfaces, grooves) that are inexpensive to manufacture, achieving the same functional result with significantly reduced manufacturing cost.
3Reliability
If conventional pre-tensioning procedures are used, then cable tension is achieved, but assembly process becomes cumbersome and difficult to automate
Solution Approach 1:
The cable tensioning system is designed to be self-service, where the friction between the drive shaft and cable automatically secures the cable at the desired tension point. This eliminates the need for complex pre-tensioning procedures that require manual adjustment and multiple steps, making the assembly process straightforward and amenable to automation.
Solution Approach 2:
The patent replaces complex mechanical pre-tensioning systems with a friction-based interface that naturally secures cable tension. By substituting intricate mechanical adjustment mechanisms with simple frictional engagement, the assembly process becomes simpler and more suitable for automated manufacturing.
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
The solution enables efficient manufacturing, assembly, and pre-tensioning of surgical instruments, reducing production costs and simplifying the tuning process, while providing a compact and high-torque-capable input device for precise surgical control.
Implementation Method 1
surface friction between the radially tapered surfaces of the drive shaft and capstan inhibits relative rotation as the end effector is adjusted during a surgical procedure
Implementation Method 2
The radial taper of the surfaces defines a self-locking taper angle, such that the capstan and drive shaft remain in the engaged state absent an external force
Data Source
AI summary
A surgical instrument includes an input device supported by a housing and coupled to a shaft. The input device comprises a drive shaft comprising a first bore, a capstan comprising a second bore, and a set screw coupling the capstan to the drive shaft. The set screw extends through at least a portion of the first bore of the drive shaft and the second bore of the capstan. The first bore of the drive shaft and the set screw are in threaded engagement with each other.