Prosthetic Ankle Module Four-Bar Linkage Dynamics
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Solution Overview
Problem
Conventional prosthetic feet lack the ability to provide dynamic movement and energy storage similar to natural ankles, limiting their ability to mimic the natural gait and rollover performance.
Innovation Solution
A prosthetic foot assembly with an ankle module that includes multiple joints allowing translational and pivotal movement, coupled with a support spring to limit motion and provide shock absorption, facilitating plantarflexion, dorsiflexion, and vertical shock absorption during various phases of the gait cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional adapters are used to couple prosthetic components, then the components can be adjusted during alignment, but the components are fixed relative to each other during use, limiting dynamic movement
Solution Approach 1:
The adapter assembly incorporates a linkage mechanism with multiple joints (first joint, second joint, third joint) that enables dynamic movement between the adapter and foot member during use. The linkage allows the foot member to pivot and translate relative to the adapter, providing dorsiflexion and plantarflexion motion that mimics natural ankle movement, thereby resolving the contradiction between fixed connection during alignment and dynamic movement during use
2Stability of the object's composition
If prosthetic feet use fixed connection between adapter and foot member, then structural stability is maintained, but the ability to store and return energy like natural ankles is lost
Solution Approach 1:
The linkage mechanism with multiple joints provides controlled mobility that allows the foot member to move dynamically relative to the adapter during the gait cycle. This dynamic connection enables energy storage and return by allowing the linkage to flex and extend, mimicking the energy-storing properties of natural ankle joints while maintaining structural integrity through the constrained motion paths defined by the joint configurations
3Productivity
If multiple joints and linkage mechanisms are added to enable dynamic movement, then rollover performance and energy storage improve, but device complexity increases
Solution Approach 1:
The prosthetic foot assembly is divided into distinct functional modules: an adapter assembly with coupling members, a linkage mechanism with multiple joints, and a foot member. This segmentation allows each component to perform its specific function while maintaining overall system manageability. The linkage mechanism is further segmented into individual joints (first joint, second joint, third joint) that can be analyzed and adjusted independently, reducing the complexity burden of having multiple moving parts
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
Enhances the rollover performance and energy storage and return of prosthetic feet, improving the user's gait by allowing dynamic movement and stability through the gait cycle.
Implementation Method 1
a support spring coupled to the adapter assembly and foot member, wherein the support spring is configured to limit the range of motion of the adapter assembly in use
Implementation Method 2
an ankle module coupling the connection sleeve to the adapter assembly via two or more joints; wherein the ankle module allows translational and/or pivotal movement of the foot member relative to the adapter assembly via the two or more joints
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A prosthetic ankle module allows for translational and/or rotational movement of a prosthetic foot relative to an adapter. The ankle module can include a four-bar linkage assembly. Links of the linkage assembly can be arranged in various configurations, e.g., parallel or non-parallel and having equal or non-equal lengths, to provide different functions and benefits, e.g., dorsiflexion, plantar flexion, vertical shock absorption, inversion, eversion, and/or rotation about the sagittal axis. Other types of linkage assemblies are also possible. A prosthetic foot can further include a support spring to limit the range of motion of the adapter in use.