Medical Manipulator Link Bar Mechanism for High Torque Precision
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Solution Overview
Problem
Existing medical manipulators face challenges in generating high gripping forces while maintaining a small offset action when gripping living body tissue, leading to operator burden and difficulty in precision due to spatial limitations and offset predictions.
Innovation Solution
A manipulator design featuring a first and second end effector with joints and a link bar system that allows angular movement, enabling increased gripping forces with minimal offset action through a power boosting mechanism and mechanical stopper functionality, allowing for efficient tissue handling without operator burden.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the output torque of the motor is increased to increase the gripping forces, then the gripping forces are improved, but the expansion and contraction properties and tensile strength of the wire, and the mechanical strength of the torque transmitting mechanism have to be increased, making it difficult to reduce the diameter of the connector
Solution Approach 1:
The torque transmission system is segmented into multiple stages with different reduction ratios. The first reduction mechanism (first gear pair) provides a first reduction ratio, and the second reduction mechanism (second gear pair) provides a second reduction ratio. This segmentation allows the motor to operate at lower torque while achieving the required output torque through cumulative reduction, thereby reducing wire and connector requirements.
Solution Approach 2:
The patent introduces a dual-gear-pair reduction system that adds a dimensional aspect to torque transmission. By arranging gear pairs at different positions and orientations within the working unit, the system achieves high torque multiplication without increasing the linear dimensions of the connector, effectively utilizing spatial arrangement to resolve the contradiction.
2Adaptability or versatility
If various components for achieving movements about the respective axes are installed in the working unit which is of a small size, then the manipulator functionality is improved, but they pose a spatial limitation on attempts to increase the speed reduction ratio in the working unit
Solution Approach 1:
The patent employs a nested arrangement where the second gear pair is positioned within or alongside the first gear pair structure. The second reduction mechanism is integrated into the existing first reduction mechanism space, allowing both mechanisms to coexist in the limited working unit volume. This nesting enables high reduction ratios without proportionally increasing the occupied space.
Solution Approach 2:
The patent implements dynamic positioning of the second end effector relative to the first end effector through the link bar and junction mechanisms. This dynamic arrangement allows the system to adapt its configuration based on operational requirements, maximizing the utility of the limited space while maintaining multiple degrees of freedom for versatile manipulation.
3Force
If a power boosting mechanism is disposed in the working unit for increasing the gripping forces of the grippers, then the gripping forces are increased, but the grippers are offset with respect to each other when they grip a living body tissue, requiring the operator to predict a vertical offset action
Solution Approach 1:
The patent employs asymmetric link lengths and junction positioning to achieve symmetric gripping action. The first link and second link have different configurations, and the link bar is positioned asymmetrically, but this asymmetry is carefully designed to compensate for potential offsets, ensuring that both end effectors converge at the same point on the tissue during gripping, eliminating the offset problem while maintaining power boosting capability.
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 manipulator achieves enhanced gripping forces and reduced offset action, enabling smooth and precise operation, improving the efficiency and accuracy of medical procedures by minimizing operator effort and preventing clip or tool misalignment.
Implementation Method 1
a link bar (36) extending from one end to another end, a first junction (54a) connecting the second joint (50b) to the first joint (50a)
Data Source
AI summary
A manipulator has a working unit in which when at least a first end effector finger and a second end effector finger are maximally closed on each other, at least the distance between a third joint axis and a first joint axis is greater than the distance between the first joint axis and a distal end of the second end effector finger, or the distance between the third joint axis and the first joint axis is greater than the distance between third joint axis and a second joint axis, or the angle formed between a direction from the third joint axis to the first joint axis and a direction from the third joint axis to the second joint axis is not π.