Passive Release Device for Prosthetic Foot Dorsal Extension
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Solution Overview
Problem
Existing prostheses are complex and costly to produce and maintain, and they do not adequately prevent tripping, especially for patients with weak muscular and coordination skills, as they require sophisticated microprocessors and sensors to manage gait phases.
Innovation Solution
A prosthesis with a release device that passively switches from a locking to a release position when ankle torque exceeds a preset threshold, allowing the foot to dorsally extend relative to the lower limb attachment part, reducing the risk of tripping by increasing ground clearance during the swing phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a microprocessor and sensors are used to control gait phases, then the prosthesis can adapt to different walking conditions, but the production and maintenance complexity increases significantly
Solution Approach 1:
The patent replaces the microprocessor-based control system with a passive mechanical release device that automatically transitions between locking and release positions based on ankle torque thresholds. This mechanical substitution eliminates sensors, actuators, and complex electronics while maintaining adaptive gait phase control through purely mechanical means.
Solution Approach 2:
The release device operates autonomously without external control signals. It self-regulates the transition between locked and released states by sensing ankle torque through its mechanical structure and automatically adjusting the foot part position according to the gait cycle phase, eliminating the need for power sources and control systems.
2Reliability
If a locking mechanism is used to prevent tripping, then stability during standing is improved, but the ability to navigate inclines and ramps is reduced
Solution Approach 1:
The patent implements a dynamic locking mechanism that transitions between locked and released states based on real-time ankle torque conditions. During standing when torque is low, the mechanism remains locked for stability. During walking when torque exceeds the threshold, it releases to allow dorsal extension for improved ground clearance and incline navigation.
Solution Approach 2:
The release device changes the mechanical state parameter of the foot part from fixed (locked) to mobile (released) based on the ankle torque parameter. This parameter-based control allows the system to adapt its mechanical properties according to the operational phase, providing both stability and mobility as needed.
3Length of moving object
If the foot part is locked in a fixed position, then ground clearance is improved during swing phase, but the prosthesis cannot accommodate different terrain conditions
Solution Approach 1:
The patent makes the foot part position dynamic rather than fixed. The dorsal extension angle is determined by the real-time ankle torque condition, allowing the system to optimize ground clearance during swing phase while adapting to different terrain conditions through passive mechanical response to torque variations.
Data Source
AI summary
A prosthesis with a lower limb attachment part, a foot part, a connection element with a joint function that connects the lower limb attachment part with the foot part, and a release device which can be brought into a locking position in which the foot part and the lower limb attachment part are connected to each other in a rotationally fixed manner at least relative to a dorsal extension movement, and into a release position in which the foot part can be rotated relative to the lower limb attachment part. The release device is designed to passively switch from the locking position into the release position when a variable which correlates to an ankle torque (M) in the connection element lies above a pre-set threshold.