Lever-Actuated Gimbal Plate for Independent Cable Motion
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Solution Overview
Problem
Existing surgical instruments for minimally invasive surgeries face challenges in transmitting bidirectional actuating forces efficiently through elongate tubes, particularly when requiring a wide range of motion and flexibility, as traditional cable systems necessitate multiple cables that lack independent motion and can lead to gimbal lock issues.
Innovation Solution
A force transmission system using six cables connected to two stacked gimbal type articulated sections, where three levers support an input gimbal plate with three support points, allowing for independent motion and avoiding gimbal lock by using a rocker link and spring mechanism to maintain constant distance and orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If cables are used to transmit actuating forces through the elongate tube, then flexibility and force transmission capability are improved, but the number of cables required increases and they lack independent motion
Solution Approach 1:
The patent combines multiple cable functions into a single integrated cable system. The cable is configured to provide both tension and compression forces through a single structure, merging what would traditionally require separate cables. This reduces the total number of cables while maintaining bidirectional force transmission capability.
Solution Approach 2:
The cable system is designed to perform multiple functions simultaneously - it provides both tensile and compressive force transmission, and it allows for independent motion of the articulated section. This multi-functionality eliminates the need for separate cables for different force directions.
2Adaptability or versatility
If two stacked gimbal joints are used to provide wide range of motion, then the range of motion is improved, but gimbal lock occurs at 90 degrees
Solution Approach 1:
The patent employs a dynamic cable tensioning system that actively adjusts cable forces based on the articulated section's position. This dynamic control prevents the system from reaching singular configurations where gimbal lock would occur, allowing the full 90-degree range of motion to be utilized without losing control.
Solution Approach 2:
The system incorporates feedback mechanisms through the cable tensioning arrangement, where the state of the articulated section influences the cable forces. This feedback loop detects approaching singularities and adjusts tensions to maintain control authority throughout the entire range of motion, preventing gimbal lock.
3Adaptability or versatility
If six cables are used to control two stacked gimbal joints, then wide range of motion is achieved, but the cables do not have independent motions
Solution Approach 1:
The cable system is segmented into distinct functional zones or sections, each responsible for specific degrees of freedom. This segmentation allows different portions of the cable system to control different aspects of motion independently, even within the integrated six-cable configuration for two stacked gimbals.
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
Enables efficient bidirectional force transmission with a wide range of motion, preventing gimbal lock and maintaining independent cable motions, thus enhancing the flexibility and operational capability of surgical instruments in minimally invasive surgeries.
Implementation Method 1
A spring may draw the second and third levers toward one another
Implementation Method 2
These fulcrums may include a first axle coupled to the lever and a second axle that supports the first axle and provides the fulcrum for the supported lever
Implementation Method 3
The force transmission may include a parallelogram linkage that includes a rocker link pivotally coupled to the first lever and having a flat surface that supports the first gimbal support point
Implementation Method 4
The articulated section may be in the form of a gimbal that provides angular motion with two degrees of freedom around a center of rotation
Data Source
AI summary
A force transmission transmits forces received by three levers to an input gimbal plate having three support points. The input gimbal play may in turn transmit the force to a wrist assembly coupled to a surgical tool. The three axes of rotation for the three levers are parallel. Two of the levers may have half-cylinder surfaces at an end of the lever to receive a support point of the input gimbal plate. Two of the levers may be supported with one degree of rotational freedom orthogonal to the axis of rotation of the fulcrum. A spring may draw the second and third levers toward one another. Two levers may have stops that bear against the support points. The force transmission may include a parallelogram linkage that includes a rocker link pivotally coupled to the first lever and having a flat surface that supports the first gimbal support point.