Surgical Instrument Wire Transmission With Low-Friction Pulley Routing
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Solution Overview
Problem
Conventional surgical instruments face issues with reduced transmission efficiency due to the use of multiple guide pulleys causing lateral friction and cable collisions, leading to increased power requirements and reduced cable life.
Innovation Solution
A surgical instrument design featuring a wire transmission system with guide pulleys configured to minimize the angle between the plane of rotation and the traction element entry point of tangency to 0-0.2°, reducing friction and eliminating collisions between traction elements, while using fewer guide pulleys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple guide pulleys are used to guide cables, then the surgical instrument can achieve multiple degrees of freedom, but transmission efficiency is reduced due to lateral friction and cable collisions
Solution Approach 1:
The patent divides the cable transmission system into separate independent channels, with each cable having its own dedicated passage. This segmentation prevents cables from crossing and rubbing against each other, eliminating lateral friction between cables while maintaining multiple degrees of freedom through independent cable actuation.
Solution Approach 2:
The patent introduces guide structures (guide holes and guide surfaces) as intermediary elements that mediate the interaction between cables and the instrument body. These intermediaries channel cables along predetermined paths, preventing cable collision and reducing friction, thereby maintaining high transmission efficiency while enabling complex motion.
2Ease of operation
If guide pulleys are oriented at large angles from cable running direction, then cable deflection is achieved, but lateral pressure and friction increase causing cable wear and potential cable dislodgement
Solution Approach 1:
The patent changes the geometric parameters of the cable path by providing guide holes with specific orientations and dimensions. The guide holes are configured to accept cables at optimized angles, controlling the deflection angle to minimize lateral pressure on the cable while achieving the necessary directional change. This parameter optimization reduces friction and prevents cable wear.
Solution Approach 2:
The patent employs curved guide surfaces and rounded guide hole geometries to smoothly redirect cables. The curved surfaces gradually change the cable direction rather than sharp angular deflections, reducing lateral pressure points and friction. This smooth curvature transition prevents cable wear and eliminates the risk of cable dislodgement while achieving effective deflection.
3Device complexity
If 6 cables are collectively passed through a rod, then the instrument structure is simplified, but cables cross and rub against each other reducing transmission performance
Solution Approach 1:
Instead of collecting all 6 cables into a single rod passage, the patent segments the cable passages into multiple separate guide holes distributed across the instrument body. Each cable travels through its own dedicated guide hole, preventing cable crossing and rubbing. This segmented approach maintains structural compactness while eliminating the harmful cable-to-cable friction that would degrade transmission performance.
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 design enhances transmission efficiency and extends the service life of the surgical instrument by minimizing friction and preventing traction element collisions, resulting in improved performance and reduced power requirements.
Implementation Method 1
the use of the pulleys tends to lead to reduced transmission efficiency, and the more pulleys are used, the greater an adverse effect will be exerted on transmission efficiency
Implementation Method 2
at least one of the guide pulleys is oriented at an angle of deflection from the running direction of the cable that it guides. With this arrangement, the cable will exert a lateral pressure on the guide pulley, causing lateral friction and increased resistance in the transmission chain
Data Source
Figure 1~2
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Figure 5
AI summary
A surgical robot and a surgical instrument are disclosed. The surgical instrument includes a wire transmission (1) and an end section (3). The wire transmission (1) includes a base (11) and n transmission modules each including at least one end drive shaft (12, 13, 14, 191, 192), two traction elements (21, 22, 23, 24, 25, 26, 201, 202, 203, 204) and two guide pulleys (161, 162, 163, 164, 165, 166, 193, 194, 195, 196). Each of the guide pulleys (161, 162, 163, 164, 165, 166, 193, 194, 195, 196) comprises a groove for receiving therein a respective one of the traction elements. The groove has a plane of rotation (Gr), an entry point of tangency and an exit point of tangency. An angle between the traction element (21, 22, 23, 24, 25, 26, 201, 202, 203, 204) defined by the end drive shaft (12, 13, 14, 191, 192) and the entry point of tangency and the plane of rotation (Gr) is in the range of 0-0.2°. Projections of all the traction elements (21, 22, 23, 24, 25, 26, 201, 202, 203, 204) at the respective exit points of tangency on the proximal end portion (300) are circumferentially arranged in the same order as the circumferential arrangement of the respective through holes (21b, 22b, 23b, 24b, 25b, 26b, 201b, 202b, 203b, 204b). This design reduces or eliminates frictional resistance between the grooves and the traction elements (21, 22, 23, 24, 25, 26, 201, 202, 203, 204) while using fewer guide pulleys (161, 162, 163, 164, 165, 166, 193, 194, 195, 196) in the wire transmission (1) of the surgical instrument. Additionally, the traction elements (21, 22, 23, 24, 25, 26, 201, 202, 203, 204) will not push or rub against one another, resulting in improved transmission efficiency of the wire transmission (1) and an extended service life of the surgical instrument.