Artificial Wrist Cable Actuation for Compact Prosthetic Design
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Solution Overview
Problem
Existing artificial wrists, particularly prosthetic wrists, face challenges with complex mechanics that result in large dimensions, high weight, and high manufacturing costs, leading to poor comfort and practicality.
Innovation Solution
An artificial wrist design featuring a static body, movable body, and a junction block with a single axis of rotation, utilizing cables and elastic means to control rotation, allowing for simple mechanics and reduced size and weight, with a rest position and activation positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex mechanics are used in artificial wrists, then rotational control is achieved, but weight and dimensions increase
Solution Approach 1:
The patent replaces traditional complex mechanical hinge systems with a cable-driven actuation system. Two cables are tensioned differently to control rotation in opposite directions, eliminating the need for heavy mechanical joints, gears, or motors while achieving reliable rotational control through tensile forces alone.
Solution Approach 2:
The invention uses flexible cables instead of rigid mechanical components to transmit actuation forces. The cables are routed through guides and anchors in a configuration that converts linear cable tension into rotational motion, providing lightweight yet effective control of the wrist joint.
2Reliability
If complex mechanics are used in artificial wrists, then rotational control is achieved, but manufacturing costs increase
Solution Approach 1:
The patent replaces complex mechanical assemblies with a simpler cable-based system that uses basic components like cable guides, anchors, and tensioning mechanisms. This substitution reduces manufacturing complexity, assembly steps, and material costs while maintaining rotational control functionality.
Solution Approach 2:
The wrist mechanism is segmented into independent cable pathways, each controlled by separate tensioning systems. This modular approach allows for easier manufacturing, testing, and replacement of individual cable assemblies rather than rebuilding entire mechanical hinge systems.
3Adaptability or versatility
If multiple elements are used in artificial wrists, then rotational functionality is achieved, but dimensions and weight increase
Solution Approach 1:
The invention employs thin, flexible cables and compact cable routing structures that occupy minimal volume. The cables pass through guides and anchors integrated into the wrist housing, creating a space-efficient actuation system that provides full rotational functionality without increasing wrist dimensions.
Solution Approach 2:
The cable system utilizes three-dimensional routing paths within the wrist structure, guiding cables through guides and anchors positioned at strategic locations. This spatial arrangement allows multiple cable pathways to coexist in a compact volume, achieving versatile rotational control without increasing overall wrist size.
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 design achieves low weight, small size, and low manufacturing costs while providing high comfort and practicality, with large rotation angles up to 140°, and easy manufacturing.
Implementation Method 1
elastic means placing the cable under tensile stress
Data Source
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AI summary
There is provided an artificial wrist (1) comprising a static body (2) adapted to be bound to a support; a movable body (3) adapted to be bound to an end effector; and a junction block (4) defining an axis of rotation (4a) between the static body and the movable body and comprising a cable (42) suitable to be moved by mutual rotation of the bodies (2) and (3) around the axis of rotation (4a), and elastic means (43) placing the cable (42) under tensile stress and working in opposition to the movement of the cable (42) so as to define a rest position in which the cable (42) and the elastic means (43) exert a zero resulting torque on the bodies (2) and (3), and an activation position in which they exert a non-zero resulting torque on the bodies (2) and (3), bringing the bodies (2) and (3) back to the rest position.