Force Transmitting Mechanism for Surgical Instruments
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Solution Overview
Problem
Existing force transmitting mechanisms in instruments, such as those using cables or wires, face inefficiencies in force transmission due to friction and mechanical losses, especially when joint portions are flexed or bent, leading to variable grasping forces and reduced control for operators.
Innovation Solution
A force transmitting mechanism with a driving member and linkages that adjust force transmission efficiency by displacing along a longitudinal axis, utilizing a support portion with a slit to guide movement and adjust angles between linkages, ensuring constant force transmission efficiency regardless of joint flexion or bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a cable or wire is used as a force transmitting member, then the structure is simple, but the force transmission efficiency decreases due to friction and mechanical losses when joint portions are flexed or bent
Solution Approach 1:
The force transmitting mechanism is divided into multiple linkages (first linkage, second linkage, third linkage) connected in series. Each linkage segment can rotate independently about its axis, allowing the mechanism to adapt to joint flexion while maintaining efficient force transmission through rotational joints rather than flexible cables that suffer from friction.
Solution Approach 2:
Rotation axes are introduced as intermediary elements between the linkages and the joint portion. These rotation axes mediate the force transmission by converting the bending motion of the joint into rotational motion of the linkages, thereby eliminating the friction losses that would occur with direct cable or wire transmission through flexed joints.
2Adaptability or versatility
If the joint portion is flexed or bent, then the instrument can adapt to different anatomical positions, but the force transmission efficiency becomes variable and control precision decreases
Solution Approach 1:
The mechanism dynamically adapts its configuration through the rotation of linkages about their axes. As the joint portion flexes or bends, the linkages automatically adjust their angular positions to maintain optimal force transmission geometry. This dynamic adaptation ensures that force transmission efficiency remains constant regardless of the joint's degree of flexion, preserving control precision across all positions.
Solution Approach 2:
The mechanism changes its geometric parameters (angular positions of linkages, orientation of rotation axes) in response to joint flexion. By dynamically adjusting these parameters, the system maintains constant force transmission efficiency even as the overall configuration changes to accommodate different anatomical positions, thereby preserving control precision.
3Adaptability or versatility
If the driving member displaces along the longitudinal axis due to joint flexion, then the mechanism accommodates joint movement, but the force transmission path length changes causing efficiency variations
Solution Approach 1:
The mechanism introduces rotational degrees of freedom about axes that are substantially perpendicular to the longitudinal axis. This dimensional change allows the linkages to accommodate longitudinal displacement caused by joint flexion through rotation rather than through changes in the force transmission path length, thereby maintaining constant force transmission efficiency.
Data Source
AI summary
A force transmitting mechanism includes: a force adjusting portion that is disposed between a joint portion of an instrument and a force generating portion and that receives force from the force generating portion; and a driving member that passes through the joint portion, that connects the end effector and the force adjusting portion, and that transmits the force applied from the force adjusting portions to the end effector, wherein, by means of displacement of the driving member associated with flexing or bending of the joint portion, the force adjusting portion increases the force transmission efficiency so that an amount of increase in the force transmission efficiency increases with an increase in a displacement amount of the driving member.