Variable Stiffness Insertion Section for Medical Devices
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Solution Overview
Problem
Existing self-propelled insertion devices face challenges in transmitting insertion force to the distal end when navigating complex body cavities like the large intestine, as the insertion section bends, leading to inefficiencies in advancing or retracting the device.
Innovation Solution
Incorporating a variable stiffness section that can adjust its stiffness based on detected conditions, controlled by a controller that adjusts the driving force supply in response to stiffness changes, allowing for optimal torque management and insertion assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the insertion section is made thin and elongated to navigate complex body cavities, then the ability to reach deep portions is improved, but the transmission of insertion force from proximal to distal end deteriorates due to excessive bending
Solution Approach 1:
The insertion section incorporates a variable stiffness mechanism that dynamically adjusts its rigidity based on operational needs. The stiffness is changed from a fixed state to a variable state, allowing the insertion section to be stiff when force transmission is needed and flexible when navigation is required. This resolves the contradiction by making the mechanical property adaptive rather than static.
Solution Approach 2:
The patent changes the physical parameter of stiffness from a constant value to a variable value. By controlling the stiffness parameter of the insertion section, the system can optimize force transmission efficiency at different stages of insertion. When the insertion section encounters resistance or needs to push through bends, the stiffness is increased to ensure force reaches the distal end effectively.
2Ease of operation
If the stiffness of the insertion section is increased to correct bends and facilitate insertion, then the ease of insertion is improved, but the ability to navigate complex flexures deteriorates due to reduced flexibility
Solution Approach 1:
The variable stiffness mechanism allows the insertion section to transition between flexible and rigid states dynamically. During navigation through complex flexures, the stiffness is reduced to allow bending and adaptation to the body cavity geometry. During insertion phases requiring force transmission, the stiffness is increased. This temporal separation of flexibility and rigidity resolves the contradiction between ease of insertion and ability to navigate flexures.
Solution Approach 2:
The insertion process involves periodic changes in the required mechanical properties of the insertion section. The system alternates between phases requiring flexibility (navigation through bends) and phases requiring stiffness (force transmission during insertion). The variable stiffness mechanism enables this periodic adjustment of mechanical properties, allowing the insertion section to optimize its performance for each phase of the insertion cycle.
Data Source
AI summary
An insertion device includes a thin and elongated insertion section, a rotating body which is rotated to advance or retreat the insertion section, a driving force supply source which supplies a driving force to the rotating body, a variable stiffness section provided for the insertion section and permitting stiffness of the insertion section to be varied, a stiffness detector which detects the stiffness of the insertion section varied by the variable stiffness section, and a controller which controls the driving force supply source in accordance with the stiffness of the insertion section detected by the stiffness detector.