Modular Prosthetic Knee Joint With Locking Linkage for Stable Bending
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Solution Overview
Problem
Traditional modular knee joints with single-shaft-bearing-and-actuating devices often cause stumbling due to insensitive resistance mechanism transitions, leading to incomplete startup or loss of resistance, especially when navigating stairs or uneven terrain.
Innovation Solution
A modular knee joint design incorporating an upper and lower connecting unit, a connecting rod assembly, locking assembly, and actuating assembly with oil storage cavities and movable plugs to control hydraulic oil flow, maintaining slow bending and resistance throughout the movement cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-shaft-bearing-and-actuating device is used in traditional modular knee joints, then the structure is simple, but the resistance mechanism transitions insensitively causing stumbling during walking
Solution Approach 1:
The single shaft is divided into two separate shafts: a first shaft for bearing and a second shaft for actuation. This segmentation allows independent optimization of bearing capacity and actuation sensitivity, resolving the contradiction between structural simplicity and transition sensitivity.
Solution Approach 2:
A connecting rod assembly is introduced as an intermediary mechanism between the upper and lower connecting units. This mediator transmits motion and force while enabling precise control of the resistance mechanism transitions, improving sensitivity without excessive complexity.
2Object-affected harmful factors
If an elastic adjustment assembly is added to reduce actuating device sensitivity, then stumbling feeling is reduced, but resistance startup becomes incomplete or lost
Solution Approach 1:
The system transitions from a static elastic adjustment assembly to a dynamic dual-shaft mechanism with independent control. The first shaft provides bearing while the second shaft controls actuation timing dynamically, ensuring complete resistance startup without stumbling.
Solution Approach 2:
The connecting rod assembly and dual-shaft configuration create a feedback mechanism that monitors the bending state and automatically triggers resistance activation at the appropriate moment, ensuring both smooth transitions and complete resistance startup.
3Productivity
If the resistance mechanism threshold is made highly sensitive to avoid waiting between steps, then walking pace is maintained, but the prosthetic shank may stumble when stepping out
Solution Approach 1:
By separating bearing and actuation functions into two shafts, the system can independently optimize the actuation threshold sensitivity without compromising overall stability. The first shaft maintains bearing stability while the second shaft provides sensitive actuation response.
Solution Approach 2:
Different parts of the mechanism have different sensitivity characteristics: the actuation mechanism (second shaft) is highly sensitive to maintain walking pace, while the bearing mechanism (first shaft) provides stable support to prevent stumbling during step initiation.
4Ease of operation
If the connecting rod assembly is allowed to pivot freely, then movement flexibility is improved, but resistance is lost during bending
Solution Approach 1:
The locking assembly is configured to automatically lock the connecting rod assembly at predetermined positions during the bending cycle. This preliminary action ensures resistance is maintained at critical phases while allowing flexibility during appropriate movement phases.
Solution Approach 2:
The connecting rod assembly alternates between locked and unlocked states in a periodic cycle: unlocked during phases requiring flexibility, and locked during phases requiring resistance maintenance. This periodic locking/unlocking maintains both flexibility and resistance.
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
Ensures stable resistance throughout the bending process, preventing stumbling on stairs and smooth movement on uneven ground by maintaining resistance during heel contact and reducing it during toe contact.
Implementation Method 1
The first connecting channel fluidly communicates with the first oil storage cavity and the second oil storage cavity... The movable plug selectively blocks the first connecting channel
Implementation Method 2
Another end of the driven unit selectively pushes the movable plug... another end of the driven unit selectively pushes the movable plug
Implementation Method 3
The locking assembly selectively locks the connecting rod assembly; therefore, the connecting rod assembly is incapable of pivoting
Data Source
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AI summary
The modular knee joint has a connecting rod assembly (20), a locking assembly (40), and an actuating assembly (30). The locking assembly selectively locks the connecting rod assembly, such that the connecting rod assembly cannot pivot. When the heel of the prosthesis contacts the ground, the connecting rod assembly activates the actuating assembly, such that when the thigh and the prosthetic shank rotate at a small angle relative to each other, the locking assembly intervenes to lock the connecting rod assembly, thereby locking the actuating assembly. Therefore, the modular knee joint can maintain the resistance during the entire bending process without losing resistance after bending to a specific angle. Therefore, the effect of maintaining gentle bending at all angles can be achieved, which can prevent the force exerted by the center of gravity from disappearing due to angle shifting, thereby eliminating the loss of resistance of the actuating assembly.