Hydraulic Prosthetic Ankle Joint with Dual Piston Dampening
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional prosthetic ankle joints require significant space and are difficult to integrate into decorative foot covers due to their design, which compromises their functionality and stability, especially in transitioning between walking and standing states without electronic control elements.
Innovation Solution
A prosthetic ankle joint design featuring two cylinders positioned posterior to the axis of rotation, with a fluid system that includes a reservoir to balance pressure fluctuations, and a non-electronic control mechanism to adjust fluid flow based on the joint's position and velocity, allowing for dynamic dampening and stable support without electronic activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two separate cylinders are interconnected via a fluid passage to provide dampening, then dorsiflexion and plantarflexion dampening is improved, but the space required becomes excessive
Solution Approach 1:
The patent combines two separate cylinders into a single cylinder with two pistons that share a common fluid chamber. This merging reduces the overall volume while maintaining the fluid displacement mechanism necessary for dampening during dorsiflexion and plantarflexion movements.
Solution Approach 2:
The single cylinder design serves multiple functions: it accommodates both dorsiflexion and plantarflexion dampening through its two-piston configuration, and the shared fluid chamber enables pressure balancing between the two movement phases, eliminating the need for separate interconnected cylinders.
2Ease of operation
If the axis of rotation is positioned further in the direction of the forefoot, then a more natural gait is achieved, but the pressure inside the fluid system increases
Solution Approach 1:
The shared fluid chamber acts as an intermediary that balances pressure between the two pistons. When the axis of rotation is positioned forward for more natural gait, the fluid system can distribute and equalize the increased pressures through the common chamber, preventing excessive pressure buildup in any single location.
Solution Approach 2:
The patent changes the physical parameters of the fluid system by using a shared chamber that allows pressure equalization. This enables the system to tolerate higher pressures generated by the forward-positioned axis while maintaining overall system stability and preventing pressure-related failures.
3Volume of moving object
If cylinders are positioned posterior of the axis of rotation, then space is reduced and axis can be moved forward, but the structural complexity increases
Solution Approach 1:
By merging two separate cylinders into one unified structure with two pistons sharing a common fluid chamber, the patent reduces the spatial footprint while the internal integration of the two-piston system manages the structural complexity through a consolidated design rather than separate components.
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
This design reduces the space required for the ankle joint, allows for a more natural gait and stable standing, and maintains stability without electronic control, mimicking the functionality of a natural ankle joint.
Implementation Method 1
The fluid resistance in this fluid passage is responsible for a dampening of the joint
Implementation Method 2
These pressure variations may occur due to thermal expansion of the fluid
Data Source
AI summary
A prosthetic joint and a method of controlling dorsiflexion and plantarflexion of the hydraulic prosthetic ankle joint. The method includes generating ground reaction forces with a hydraulic prosthetic ankle, wherein the prosthetic hydraulic ankle comprises a first chamber and a second chamber, and the ankle is connected to a prosthetic foot; rotating the prosthetic foot in response to the ground reaction force; transferring fluid between the forward and rear chambers in response to rotation of the foot; providing a feature to occlude or partially occlude the fluid transfer between chambers; providing a non-electronic mechanism for controlling the flow responsive to both a position of the joint and a rate of change of position of the joint, and wherein the mechanism is arranged such that a dwell at a particular joint location or locations will occlude the flow path.