Articulated Surgical Instrument Cable Routing for Higher Closing Torque
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing surgical instruments face challenges in miniaturization, particularly in maximizing closing torque and minimizing stress on actuating cables while maintaining mobility and avoiding bulky bends in articulated ends, especially when using small gauge cables or polymer cables with limited breaking force and low rigidity.
Innovation Solution
The surgical instrument features a support structure with convex ruled sliding surfaces and a winding pulley configuration, allowing transmission cables to slide on orthogonal surfaces and wind around a pulley with a greater radius than the instrument's diameter, optimizing cable load and maintaining minimal friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the radius of the distal actuation pulley is increased to maximize closing torque, then the closing torque increases, but the longitudinal size of the surgical instrument increases
Solution Approach 1:
The patent transitions from a longitudinal arrangement to a transverse arrangement by positioning the distal actuation pulley to protrude transversally with respect to the longitudinal axis. This allows the pulley radius to be greater than or equal to the distance between the cable sliding surface and the central axis, maximizing closing torque without increasing the longitudinal size of the instrument.
2Volume of moving object
If small gauge cables or polymer cables are used to miniaturize the instrument, then the instrument size decreases, but the cable breaking force and rigidity are reduced
Solution Approach 1:
The patent introduces a convex ruled sliding surface that guides and supports the transmission cable before it reaches the distal actuation pulley. This preliminary guidance structure ensures proper cable alignment and distribution of mechanical loads, allowing small gauge or polymer cables to be used without compromising strength, as the cable is protected from excessive stress concentrations.
3Force
If the transmission cable is wound around a large radius pulley to increase closing torque, then the closing torque increases, but the cable friction and stress increase
Solution Approach 1:
The patent introduces a convex ruled sliding surface as an intermediary element between the transmission cable and the distal actuation pulley. This sliding surface guides the cable with minimal friction and properly distributes the mechanical loads, reducing cable friction and stress while still allowing the cable to be wound around a large radius pulley to maximize closing torque.
4Force
If the distal actuation pulley protrudes transversally to maximize closing torque, then the closing torque is maximized, but the device complexity increases
Solution Approach 1:
The patent merges the distal actuation pulley with the second link, making them a single integrated component. This integration simplifies the overall device structure while maintaining the transverse protrusion configuration that maximizes closing torque, reducing the number of separate parts and assembly steps.
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
This configuration enhances closing torque and reduces cable stress, ensuring durable and reliable operation of miniaturized surgical instruments with improved mobility and reduced bulkiness.
Implementation Method 1
by virtue of the low sliding friction of the tendons, they are capable of remaining in contact with the convex ruled surface of a link over a relatively long and arcuate longitudinal segment
Data Source
AI summary
A surgical instrument includes an articulated end having a first support link, a second link articulated with respect to the first support link about a rotation axis, and a transmission cable fixed to the second link. The first support link has at least one first convex ruled surface with straight generator lines all parallel to each other, and a second convex ruled surface with straight generator lines all parallel to each other. The transmission cable is configured to slide on both the at least one first convex ruled surface and the second convex ruled surface of the first support link when the second link rotates with respect to the first support link. The straight generator lines of the at least one first convex ruled surface are orthogonal to the straight generator lines of the second convex ruled surface.