Adaptive Prosthetic Socket Using Hydraulic Actuation
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Solution Overview
Problem
Amputees often experience discomfort and instability due to fluctuations in residual limb volume, leading to improper fit of prosthetic devices, which can cause skin breakdown and secondary disabilities, as existing solutions are socially unacceptable, time-consuming, and difficult for non-technically-minded individuals to implement.
Innovation Solution
A prosthetic device equipped with hydraulic actuators and a closed-loop control system that senses ambulatory state, force, and pressure to automatically adjust the fit by using incompressible fluid and customizable pressure distribution, detecting undesirable 'pistoning' and adapting pressure based on limb volume changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If amputees manually adjust fit using socks or bladders, then fit can be accommodated for fluid volume loss, but the process requires removing prosthesis and outer clothing which is socially unacceptable, time-consuming, and difficult to implement
Solution Approach 1:
The system uses sensors to automatically detect limb volume changes and triggers the hydraulic actuator to adjust socket pressure without user intervention. The control system autonomously monitors and adjusts fit parameters, eliminating the need for manual operation by the amputee.
Solution Approach 2:
Manual mechanical adjustment methods (socks, bladders requiring manual inflation) are replaced with an automated hydraulic actuation system controlled by electronic sensors and a control algorithm, enabling automatic adaptation to volume changes.
2Reliability
If traditional static sockets are used, then device simplicity is maintained, but improper fit causes skin breakdown, discomfort, and instability during ambulation
Solution Approach 1:
The static socket is transformed into a dynamic system with adjustable pressure characteristics. The hydraulic actuator modifies the mechanical properties of the socket in real-time based on detected limb volume changes, maintaining optimal fit throughout the day.
Solution Approach 2:
A sensor provides feedback about limb volume or socket pressure to the control system, which then adjusts the hydraulic actuator to maintain proper fit. This closed-loop control ensures reliable fit adaptation while managing system complexity through intelligent control algorithms.
3Adaptability or versatility
If hydraulic actuators with multiple bellows portions are used, then precise pressure control and adaptive fit are achieved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The hydraulic actuator is divided into multiple bellows portions (first, second, and third bellows) that can be manufactured and assembled separately. Each bellows portion connects to specific pressure distribution zones, allowing modular manufacturing and assembly while achieving complex pressure control patterns.
Solution Approach 2:
Different bellows portions apply pressure to different local zones of the residual limb through connected pressure distribution portions. This segmented approach allows tailored pressure application to specific anatomical regions, improving adaptive control while enabling modular manufacturing.
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 provides a comfortable, stable, and adaptive fit for amputees by automatically adjusting to changes in residual limb volume, reducing skin breakdown and improving quality of life by integrating sensors and actuators for real-time pressure control.
Implementation Method 1
A prosthetic device equipped with hydraulic actuators and a closed-loop control system that senses ambulatory state, force, and pressure to automatically adjust the fit by using incompressible fluid
Implementation Method 2
sense parameters including ambulatory state of a user along with force or pressure applied by the prosthetic device to a residual limb of the user
Data Source
AI summary
An incompressible fluid is used to adjust fit for a prosthetic device, the use of a closed loop control system and force, motion, and position measurement to aid with algorithms controlling the fit of the prosthetic device to a residual limb. Embodiments include automatic actuation, based on triggering of threshold values from sensors, a powered full release feature, use of hydraulic transducers to transfer fluid pressure to force on a limb, and customizable pressure distribution pads and embedded valves in transducers to prevent backflow and allow stabilization of the residual limb. A retrofit system may be used for existing prosthetic sockets. A triggering algorithm utilizes measured force exceeding a threshold or thresholds with a characteristic pulse signature and a triggering of release based on a combination of total motion and measured force below a threshold or thresholds.