Steerable Instrument Assembly with Releasable Longitudinal Supports
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Solution Overview
Problem
Assembling a steerable instrument with intermediate cylindrical elements having longitudinal steering elements is difficult due to decreased bending stiffness, leading to uncontrolled deformation and potential damage, which results in deteriorated performance.
Innovation Solution
The method involves coupling inner, outer, and intermediate cylindrical elements with releasable or flexible attachments between adjacent longitudinal elements, allowing controlled movement during assembly and reducing radial movement, using techniques like wax or glue for temporary connections, or fracture elements that can be broken during assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If intermediate cylindrical elements with longitudinal steering elements are used, then steering precision is improved, but bending stiffness decreases leading to uncontrolled deformation
Solution Approach 1:
The intermediate cylindrical element is segmented into multiple longitudinal elements that can move independently. This segmentation allows the structure to maintain steering precision through controlled movement of individual elements while reducing overall bending stiffness to enable flexibility. The longitudinal elements are separated by gaps that allow relative movement, resolving the contradiction between precision and flexibility.
Solution Approach 2:
The intermediate cylindrical element transitions from a static rigid structure to a dynamic structure where longitudinal elements can move relative to each other. This dynamic capability allows the element to adapt its stiffness characteristics - maintaining rigidity when needed for precision while allowing controlled deformation for flexibility. The movement of longitudinal elements is constrained by guide surfaces that prevent uncontrolled deformation.
2Adaptability or versatility
If longitudinal elements are made independent for steering control, then steering capability is improved, but assembly difficulty increases due to uncontrolled deformation
Solution Approach 1:
The intermediate cylindrical element is pre-assembled with longitudinal elements in a controlled manufacturing environment where deformation can be managed. The element is given a predetermined shape or pre-stressed state before final assembly into the instrument. This preliminary action ensures that when the element is later installed, the longitudinal elements are already positioned correctly, reducing assembly difficulty despite their independence.
Solution Approach 2:
A guide structure or constraint mechanism acts as an intermediary between the independent longitudinal elements and the rest of the instrument assembly. This intermediary component controls the movement of longitudinal elements during assembly, preventing uncontrolled deformation while still allowing the steering capability to function. The guide surfaces constrain lateral movement while permitting the necessary longitudinal sliding for steering.
3Manufacturing precision
If releasable attachments are used between longitudinal elements, then manufacturing control is improved, but device complexity increases
Solution Approach 1:
Temporary attachment elements are used during manufacturing to hold longitudinal elements in the correct position, then these attachments are discarded or removed after serving their purpose. The attachments are not permanent components but rather manufacturing aids that are discarded after assembly. This approach provides manufacturing control without permanently increasing device complexity, as the attachments are recovered (removed) after use.
Data Source
AI summary
A steerable instrument for endoscopic and/or invasive type applications includes an elongated tubular body having a proximal end part, a distal end part and an intermediate part between proximal and distal end parts, the proximal end part having at least one actuation proximal zone. The distal end part has at least one flexible distal zone, and the elongated tubular body is configured such that a movement of an actuation proximal zone is transferred to a corresponding flexible distal zone for a corresponding movement thereof. The elongated tubular body includes an inner, outer, and intermediate cylindrical elements having longitudinal elements between the inner and outer cylindrical elements. Inner, outer and intermediate cylindrical elements are coupled so movement of an actuation proximal zone is transferred by the longitudinal elements of one of the intermediate cylindrical elements to a corresponding flexible distal zone.