Medical Instrument Roll Gear Train With Compressible Backlash Control
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Solution Overview
Problem
Medical instruments for minimally-invasive procedures require precise control of multiple mechanical degrees of freedom, which is difficult for human operators and often complex to assemble, especially when integrating with robotic systems.
Innovation Solution
A medical instrument incorporating a roll mechanism with a spur gear and beveloid gear system, utilizing a compressible gear design to accommodate manufacturing variations and minimize backlash, allowing for precise control and easy assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a robot is employed to control multiple degrees of freedom of the medical instrument, then the ease of operation is improved, but the device complexity increases
Solution Approach 1:
The instrument shaft is divided into multiple segments that can rotate independently relative to each other, with each segment controlled by a separate degree of freedom mechanism. This segmentation allows the complex multi-DOF control to be broken down into manageable modular units, improving ease of operation while keeping each module's complexity controlled
Solution Approach 2:
Multiple instrument shaft segments are nested within each other, with each segment capable of rotation about its own axis. The distal segments are positioned within hollow sections of proximal segments, creating a telescopic structure that provides multiple rotational degrees of freedom in a compact configuration, thereby improving operational capability without proportionally increasing overall device complexity
2Adaptability or versatility
If the instrument shaft and rotation axis are at an angle, then the adaptability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The gear train incorporates a compressible gear that can dynamically adjust its position and compression state during operation. This dynamic capability allows the mechanism to accommodate angular misalignments between the instrument shaft and rotation axis that arise from manufacturing variations, providing adaptability without requiring extremely tight manufacturing tolerances
Solution Approach 2:
The compressible gear changes its physical state by compressing and expanding radially, altering its effective dimensions and position within the gear train. This parameter change enables the mechanism to compensate for angular deviations and maintain proper gear meshing despite manufacturing variations in the angles between shafts and rotation axes
3Reliability
If a compressible gear is used to accommodate manufacturing variations, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The compressible gear is designed to dynamically compress and expand in response to radial forces during gear engagement. This dynamic behavior automatically compensates for manufacturing variations in the gear train, improving reliability by maintaining proper meshing conditions without requiring additional adjustment mechanisms or complex control systems
Solution Approach 2:
The compressible gear serves itself by using the natural radial forces generated during normal gear operation to compress and expand, thereby self-adjusting to accommodate manufacturing variations. This self-service mechanism improves reliability without adding external control systems or complex adjustment devices
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 solution provides precise control of instrument shaft rotation with reduced backlash, enabling intuitive operation and efficient assembly, suitable for use in robotic systems.
Implementation Method 1
the compressible gear is able to deflect radially away from the interference
Implementation Method 2
a spur gear and a beveloid gear to accommodate an angle between the instrument shaft and a rotation axis of an input spindle
Data Source
AI summary
A medical instrument includes a roll mechanism that rotates an instrument shaft. The roll mechanism may include a first gear coupled to the instrument shaft and meshed with a second gear. One of gears may be a spur gear while the other gear may be a beveloid gear. Further, the spur gear and the beveloid gear may be in a gear train containing a compressible gear, e.g., a gear with an inner center piece, an outer ring, and a flexible interconnecting structure between the inner center piece and the outer ring. With a compressible gear, an interference fit of in the gear train may be within manufacturing variations of the gear train, and the compressible gear may deflect radially away from the interference fit.