Drum Transmission Assembly for Instrument Insertion and Slack Prevention
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Solution Overview
Problem
Existing transmission assemblies for remotely-controlled instruments face challenges in providing an insertion degree of freedom movement by driving relative translation between the transmission assembly and the instrument shaft while maintaining a simple and compact architecture, and issues such as fluid leakage and slack development in actuation elements.
Innovation Solution
The transmission assembly includes a rotatable drum with actuation elements wound around it, a first and second rotatable drive shaft with a bearing, and a biasing device to prevent slack, along with a seal to prevent fluid leakage, allowing for compact design and reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the transmission assembly drives relative translation between the transmission assembly and the instrument shaft to provide insertion degree of freedom movement, then the insertion functionality is improved, but the device complexity increases
Solution Approach 1:
The patent implements nesting by placing the instrument shaft within the transmission assembly housing, with the shaft passing through the housing structure. The actuation elements are nested within the transmission assembly, wound around drums that are mounted inside the housing. This nested arrangement allows the transmission assembly to drive relative translation between itself and the shaft while maintaining a compact, integrated structure rather than separate components.
2Reliability
If actuation elements are used to transmit force from the transmission assembly to the instrument shaft, then the force transmission function is improved, but slack development occurs reducing reliability
Solution Approach 1:
The patent applies preliminary anti-action by using springs positioned to continuously bias the actuation elements into tension. The springs are pre-loaded to exert a constant force that prevents the actuation elements from going slack during operation. This preliminary counteracting force ensures that the actuation elements remain taut and reliable throughout the instrument's operational range.
3Adaptability or versatility
If the transmission assembly is designed with multiple drive members and actuation elements, then the functionality is improved, but fluid leakage paths increase
Solution Approach 1:
The patent employs seals positioned at critical interfaces within the transmission assembly to block fluid leakage paths. These seals create flexible barriers that maintain fluid integrity while allowing the necessary relative motion between the transmission assembly components and the instrument shaft. The seals are strategically placed where fluid leakage would otherwise occur due to the presence of multiple drive members and actuation elements.
Data Source
AI summary
A medical instrument comprises a shaft, a movable component coupled to the shaft, a first actuation element coupled to the instrument shaft, a second actuation element coupled to the movable component, and a transmission assembly movably coupled to the instrument shaft. The transmission assembly comprises: a first drive member comprising a drum which is rotatable to drive translation of the instrument shaft relative to the transmission assembly by actuating the first and second actuation elements which are wound around the drum; a second drive member comprising a first rotatable drive shaft which is rotatable to actuate the second actuation element; and a third drive member comprising a second rotatable drive shaft and a bearing coupled to the second rotatable drive shaft. The second actuation element is routed over the bearing between the rotatable drum and the first rotatable drive shaft.