Hydraulic Prosthetic Ankle With Diverter Valve for Swing Clearance
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Solution Overview
Problem
Existing prosthetic and orthotic devices face challenges in smoothly transitioning between different phases of the gait cycle, particularly in preventing the prosthetic foot from dragging during the swing phase, which can cause tripping and discomfort.
Innovation Solution
A hydraulic prosthetic ankle system with a hydraulic cylinder, valves, and a diverter valve that controls fluid flow to facilitate plantarflexion and dorsiflexion, using adjustable dampening resistance to enhance gait control and lift the prosthetic foot during the swing phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic dampening is used to control plantarflexion and dorsiflexion, then gait control is improved, but hydraulic resistance increases causing difficulty in foot lift during swing phase
Solution Approach 1:
The system dynamically switches between two hydraulic passages based on gait phase. During swing phase, the diverter valve directs flow through the third passage with lower dampening to facilitate foot lift. During stance phase, flow is directed through the second passage with higher dampening for controlled dorsiflexion. This dynamic configuration resolves the contradiction by providing low resistance when needed for movement initiation while maintaining high control during weight-bearing phases.
Solution Approach 2:
The hydraulic system is segmented into multiple passages with different dampening characteristics. The second passage provides high-dampening flow control for stance phase stability, while the third passage provides low-dampening flow for swing phase mobility. The diverter valve segments the flow paths, allowing selective engagement of appropriate dampening levels for each gait phase, thus resolving the force-resistance contradiction.
2Stability of the object's composition
If high dampening is used during dorsiflexion, then stability is improved, but foot lift capability during swing phase deteriorates
Solution Approach 1:
The system dynamically adjusts dampening levels by switching passages. During swing phase, the third passage with lower dampening is engaged to enable rapid foot lift. During dorsiflexion in stance phase, the second passage with higher dampening is engaged to provide stability. This dynamic adaptation resolves the contradiction between stability and speed by providing the appropriate dampening level for each operational phase.
Solution Approach 2:
Different passages are designed with different local dampening qualities tailored to specific functional requirements. The second passage has high dampening quality for stable controlled movement during stance, while the third passage has low dampening quality for rapid movement during swing. The diverter valve selects the appropriate local quality for each phase, resolving the stability-speed contradiction.
3Ease of operation
If hydraulic resistance is reduced for swing phase, then foot dragging is prevented, but control during stance phase deteriorates
Solution Approach 1:
The system dynamically reconfigures hydraulic resistance based on gait phase requirements. During swing phase, the diverter valve directs flow through the third passage with lower resistance to ensure easy foot clearance and prevent dragging. During stance phase, flow is directed through the second passage with higher resistance to maintain reliable control. This dynamic reconfiguration resolves the contradiction between ease of operation and reliability.
Solution Approach 2:
The hydraulic control is segmented into distinct flow paths with different resistance characteristics. The third passage provides low-resistance flow for swing phase ease of operation, while the second passage provides high-resistance flow for stance phase reliability. The diverter valve segments the operational requirements, assigning appropriate resistance levels to each phase, thus resolving the contradiction.
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 improved gait control by reducing hydraulic resistance, allowing the prosthetic foot to maintain a dorsiflexed position, thereby preventing dragging and enhancing user mobility.
Implementation Method 1
The first and second chambers are filled with hydraulic fluid. The first valve is disposed along a first passage, the first passage and first valve allowing dampened fluid flow between the first and second chambers during plantarflexion.
Implementation Method 2
The prosthetic ankle may include a spring disposed in the hydraulic cylinder and operatively coupled to the piston. The spring may impart a force on the piston during swing phase to dorsiflex a prosthetic foot coupled to the prosthetic ankle to lift a toe of the foot.
Data Source
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AI summary
A prosthetic ankle device is disclosed herein. The prosthetic ankle device includes a hydraulic cylinder with a first chamber, a second chamber, and a piston separating the first chamber and the second chamber. The chambers are filled with hydraulic fluid. During plantarflexion, the hydraulic fluid flows between the first chamber and the second chamber via a first passage and a first check valve. During dorsiflexion, the hydraulic fluid flows between the first chamber and the second chamber via a second passage and a second check valve. The ankle device includes a third passage and a third check valve, where the third passage diverts flow of the hydraulic fluid from the second passage based at least in part on a system status.