Wire-Driven Medical Arm Tip for Compact Backlash-Free Endoscope Support
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing medical arm devices for laparoscopic surgery are bulky and prone to backlash, hindering the operation of medical instruments and endoscopes, and lack a compact design with high torque and multi-degree-of-freedom active joints.
Innovation Solution
A medical arm device with a tip part featuring three orthogonal rotation axes (yaw, pitch, and roll) is designed using wires and pulleys, including rerouting pulleys with different diameters and interference avoidance structures to minimize size and backlash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large tip part is used to support the endoscope, then the endoscope can be held stably, but the operation of the medical instrument by the surgeon is hindered
Solution Approach 1:
The patent condenses three rotation axes (roll, pitch, yaw) into a nested configuration where the roll axis is contained within the pitch axis structure, and the pitch axis is contained within the yaw axis structure. This nesting allows the multi-degree-of-freedom active joint to achieve high torque while maintaining a compact tip part diameter, thus stabilizing the endoscope without hindering the surgeon's operation.
2Adaptability or versatility
If a gear-based transmission mechanism is used, then infinite rotation structure is easily realized, but backlash is easily generated in the transmission part
Solution Approach 1:
The patent replaces the gear-based mechanical transmission system with a wire-based transmission system. Wires are wound around pulleys attached to each rotation axis, eliminating the meshing gears that cause backlash. This substitution maintains infinite rotation capability while significantly reducing transmission errors and improving positioning precision.
3Manufacturing precision
If a wire-based transmission mechanism is used, then backlash is reduced, but the structure becomes more complex
Solution Approach 1:
The patent merges multiple transmission functions into a unified wire-based system. The same wire that transmits torque for one rotation axis also serves as a routing path for controlling other axes through strategically placed rerouting pulleys. This consolidation reduces the number of separate transmission components while achieving backlash-free operation.
4Adaptability or versatility
If rerouting pulleys are added to transmit rotation between axes, then multi-degree-of-freedom control is achieved, but the tip part size increases
Solution Approach 1:
The patent utilizes three-dimensional spatial arrangement to position the rerouting pulleys and rotation axes. By distributing components along the longitudinal axis and utilizing radial space efficiently, the design achieves multi-degree-of-freedom control without significantly increasing the overall tip part diameter, maintaining a compact profile suitable for laparoscopic surgery.
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 device provides a compact, lightweight arm that supports endoscopes with high torque and freedom, reducing interference with other instruments and surgeons, and minimizing motor load and power consumption.
Implementation Method 1
a first rerouting pulley that reroutes the first wire between the pitch axis and the yaw axis, a second rerouting pulley that reroutes the second wire between the pitch axis and the yaw axis, and a third rerouting pulley that reroutes the second wire between the yaw axis and the roll axis are disposed on the link
Data Source
AI summary
A medical arm device to support a medical instrument has a tip part with a structure in which three rotation axes are disposed in order of a rotation axis around a longitudinal axis of the medical instrument, a yaw axis that rotates the medical instrument left and right with respect to a tip of a link, and a pitch axis that rotates the medical instrument up and down with respect to the tip of the link, and a first wire for rotation transmission of the yaw axis, a second wire for rotation transmission of the roll axis, a first rerouting pulley that reroutes the first wire between the pitch axis and the yaw axis, a second rerouting pulley that reroutes the second wire between the pitch axis and the yaw axis, and a third rerouting pulley that reroutes the second wire between the yaw axis and the roll axis.