Prosthetic Wrist Bearing Assembly for Free Rotation Under Load
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Solution Overview
Problem
Current mechanical wrist units in prosthetic devices tend to bind under high rotational or axial loads in free-rotation mode, compromising their functionality and comfort.
Innovation Solution
A laminated mechanical wrist unit with a combination thrust bearing and tapered bearing design, along with a twist ring mechanism, allows for free rotation under load and precise angular locking, using an adapter with a standard threaded stud for secure attachment of terminal devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mechanical wrist unit is designed for free rotation mode, then the terminal device can rotate freely under load, but the wrist unit tends to bind under high rotational or axial load
Solution Approach 1:
The bearing assembly is segmented into multiple independent bearing components (thrust bearing for axial loads, tapered bearing for radial loads) that work together to handle different load types separately, preventing binding by distributing load management across specialized components
Solution Approach 2:
The patent changes the physical parameters of the bearing surfaces through specific geometric configurations (tapered angles, thrust surfaces) and material selections to optimize friction characteristics and load distribution, enabling smooth rotation under high load conditions
2Measurement precision
If a mechanical wrist unit is designed for rotation-locked mode with angular specificity, then precise angular positioning is achieved, but the complexity of the locking mechanism increases
Solution Approach 1:
The locking mechanism transitions from static to dynamic through a cam-actuated system that can rapidly switch between locked and unlocked states, reducing operational complexity while maintaining precise angular positioning capability when needed
Solution Approach 2:
A cam mechanism serves as an intermediary between the user's locking action and the final angular position, translating a simple rotational input into precise angular locking without requiring complex direct control mechanisms
3Stability of the object's composition
If a terminal device is securely attached to the wrist unit, then stability under load is improved, but the attachment and detachment process becomes more time-consuming
Solution Approach 1:
The adapter and wrist unit interface is pre-configured with aligned bearing surfaces and locking features, so that when the terminal device is attached, stability is immediately established without requiring sequential adjustment steps, reducing attachment time while maintaining security
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 secure attachment and full rotation of terminal devices under all realistic load cases with fine angular specificity, enhancing the usability and comfort of prosthetic limbs.
Implementation Method 1
A combination thrust bearing and tapered bearing enables the free rotation under high load as desired
Implementation Method 2
Current designs of mechanical wrist units have a tendency to bind under high rotational or axial load when in free-rotation mode
Data Source
AI summary
A prosthetic wrist for terminal devices preserves free rotation under high rotational or axial loads.