Self-Adjusting Lower Limb Prosthetic Socket With Threshold Tightening
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Solution Overview
Problem
Conventional prosthetic sockets are rigid and unable to accommodate short-term and long-term fluctuations in the volume and shape of a residuum, leading to discomfort and pain due to inadequate fit, and existing solutions involving complex sensors and manual adjustments are cumbersome and costly.
Innovation Solution
A self-adjusting socket system with a resilient resistive element and actuators that tighten around the residuum until a threshold tightness is reached, then yield to prevent further tightening, using a mechanical linkage and locking mechanism to maintain fit without manual intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional rigid sockets are used, then manufacturing is simple and cost is low, but they cannot accommodate fluctuations in residuum volume and shape leading to discomfort and pain
Solution Approach 1:
The socket incorporates a dynamic adjustment mechanism with actuators that can change the socket's volume and shape in response to residuum fluctuations. The retention mechanism includes movable panels and adjustable components that allow the socket to adapt its configuration over time, transitioning from a static rigid structure to a dynamic adaptable one.
Solution Approach 2:
The socket utilizes resistive elements with adjustable resistance characteristics that can modify the mechanical properties of the retention mechanism. By changing the resistance parameter of these elements, the socket can accommodate different volumes and shapes of the residuum, allowing for adaptation without requiring complete structural redesign.
2Adaptability or versatility
If manual adjustment mechanisms are added to accommodate residuum changes, then adaptability improves, but ease of operation deteriorates due to frequent manual interventions required
Solution Approach 1:
The socket incorporates self-adjusting mechanisms that automatically respond to changes in residuum volume without requiring manual intervention. The actuators are triggered by the natural movement and pressure changes within the residuum, allowing the socket to self-regulate its retention force and volume adaptation over time.
Solution Approach 2:
The system includes feedback mechanisms where the mechanical environment within the socket (such as pressure changes, movement patterns, and residuum volume fluctuations) is sensed and fed back to the actuators. This feedback loop enables the socket to automatically adjust its configuration in response to actual residuum conditions without external intervention.
3Measurement precision
If complex electronic sensor systems are used to monitor and adjust socket fit, then measurement precision and adaptability improve, but device complexity and cost increase significantly
Solution Approach 1:
The patent replaces complex electronic sensor systems with simpler mechanical sensing and actuation mechanisms. The actuators are triggered by direct mechanical contact and pressure changes within the residuum rather than electronic sensors, eliminating the need for power sources, electronics, and complex control systems while maintaining the ability to detect and respond to volume changes.
Solution Approach 2:
The system uses simple, inexpensive mechanical components such as resistive elements, springs, and basic actuators that can be easily replaced if needed. These mechanical components are far cheaper and simpler than electronic sensor systems, providing sufficient functionality for monitoring and adjusting socket fit without the complexity and cost of electronic alternatives.
4Reliability
If the retention mechanism is made very tight to ensure secure fit, then reliability of connection improves, but comfort and ease of operation worsen due to excessive tightness
Solution Approach 1:
The retention mechanism incorporates dynamic adjustment capabilities that allow it to vary its tightness level based on actual needs. The movable panels and adjustable components enable the socket to provide firm retention when needed while allowing for comfort and breathability during normal use, transitioning between tight and relaxed states as required.
Solution Approach 2:
The system utilizes resistive elements with variable resistance characteristics that can modify the tightness of the retention mechanism. By adjusting the resistance parameter of these elements, the socket can achieve reliable connection when necessary while maintaining comfort during daily activities, allowing for parameter-based control of tightness levels.
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 system provides a comfortable and secure fit by automatically adjusting to residuum changes, reducing the need for frequent manual adjustments and minimizing discomfort, while avoiding the complexity and cost of electronic systems.
Implementation Method 1
each step transmits motion to a resilient resistive element coupled to an actuator. The resistive element can transmit the motion to the actuator to cycle the actuator
Implementation Method 2
When the tightness of the retention mechanism has reached the threshold, on each further step the resistive element yields to absorb the motion, so that the actuator fails to cycle on each further step
Data Source
AI summary
The present disclosure describes self-adjusting sockets for lower limb prostheses in which each step transmits motion to a resilient resistive element coupled to an actuator configured to cycle between a rest position and an actuated position. The resistive element can transmit the motion to the actuator to cycle the actuator. Each cycle of the actuator acts through a mechanical linkage to tighten the socket around the residuum, until a desired threshold tightness on the residuum is reached. After the threshold tightness is reached, the resistive element yields and absorbs the motion rather than transmitting the motion, so that the actuator ceases to cycle on each step, preventing further tightening beyond the threshold.