Scotch-Yoke Prosthetic Wrist Module for Weight Reduction
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Solution Overview
Problem
Existing prosthetic wrist modules are bulky, heavy, and costly due to high complexity, limiting their potential use and effectiveness in replicating the range of motion of a natural wrist.
Innovation Solution
A passive module of flexion-extension with Scotch-Yoke mechanisms and compression springs that transforms rotary motion into linear motion, allowing for adjustable stiffness and reduced weight, combined with an independent active pronation-supination module using a gear motor, enabling a modular and customizable prosthetic wrist joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If complex active wrist modules with multiple motors are used to achieve multiple degrees of freedom, then the range of motion is improved, but the weight and dimensions increase significantly
Solution Approach 1:
The artificial wrist is divided into separate functional modules: an active pronation-supination module with a motor and a passive flexion-extension module with elastic elements. This segmentation allows each module to be optimized independently, reducing the overall weight while maintaining the full range of motion capabilities through modular assembly.
Solution Approach 2:
The invention transitions from a fully active system to a hybrid active-passive system. The passive flexion-extension module uses elastic elements that dynamically adapt to user movements without requiring motors, reducing weight while preserving the natural range of motion through elastic energy storage and release.
2Adaptability or versatility
If complex active wrist modules with multiple motors are used to achieve multiple degrees of freedom, then the range of motion is improved, but the device complexity and cost increase
Solution Approach 1:
The wrist module is segmented into independent functional units with distinct control strategies. The active pronation-supination module handles orientation control with a single motor, while the passive flexion-extension module provides natural movement without active control, simplifying the overall system architecture and reducing complexity.
Solution Approach 2:
The passive flexion-extension module operates autonomously using elastic elements that automatically respond to user movements without requiring external control signals or complex electronics. This self-service approach simplifies the control system while maintaining full flexion-extension functionality.
3Device complexity
If passive friction systems are used for wrist positioning, then the device simplicity is improved, but the adjustability and precision are reduced
Solution Approach 1:
The positioning functionality is segmented between the active pronation-supination module, which provides precise angular positioning through motor control, and the passive flexion-extension module, which provides natural movement ranges. This segmentation allows each module to optimize its positioning capabilities for its specific function.
Solution Approach 2:
The active pronation-supination module incorporates adjustable parameters such as motor torque, gear ratios, and control algorithms that can be modified to optimize positioning precision and adaptability. This allows the system to maintain simplicity while achieving high adjustability through parameter optimization rather than structural complexity.
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 reduces the weight and dimensions of prosthetic wrist modules while maintaining reliability and strength, allowing for adjustable elastic behavior and achieving a range of motion similar to a natural wrist with reduced costs.
Implementation Method 1
a passive module of flexion-extension (1000) comprising mechanical moving means (4, 5) connected to said proximal base (1) and distal base (2), said mechanical moving means (4, 5) comprising at least one compression spring (4)
Implementation Method 2
A passive module of flexion-extension with Scotch-Yoke mechanisms and compression springs that transforms rotary motion into linear motion
Data Source
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AI summary
The present invention refers to a module of flexion-extension (1000) for an artificial articulation (10), comprising: a proximal base element (1 ), configured to connect to a prosthetic socket (100); a distal base element (2), configured to connect to a prosthesis (101 ); mechanical connection means (20) of the proximal base element (1 ) to the distal base element (2), configured in such a way as to allow a rotation of the distal base element (2) with respect to the proximal base element (1 ) in such a way as to realize a movement of flexion-extension of the prosthesis (101) with respect to the socket (100); stressing means (6) connected to the mechanical connection means (20) and to respective elastic reaction means (40) configured to exert a reaction force apt to counteract the rotation of the distal base element (2) wherein said mechanical connection means (20) comprises at least one Scotch- Yoke mechanism suitable for transforming a rotary motion of the distal base element (2) into a linear motion of the stressing means (6), such that when the means of mechanical connection means (20) is operated, the stressing means (6) is linearly moved to elastically deform said elastic reaction means (40), and when the mechanical connection means (20) is not operated, the elastic reaction means (40) is configured to maintain the proximal base element (1 ) and the distal base element (2) in a rest configuration.