Differential and Variable-Stiffness Ankle-Foot Orthosis With Gait Feedback
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Solution Overview
Problem
Existing ankle foot orthoses (AFOs) do not adequately address the need for adjustable and variable stiffness to assist or resist ankle motion, requiring manual calibration and lacking integration with user data for intelligent adjustments.
Innovation Solution
AFOs with adjustable tensioning components, modular design, and integrated sensors for differential and variable stiffness, allowing manual or automated adjustments based on user data to provide assistive or resistive torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing AFOs use fixed stiffness design, then device complexity is reduced, but adaptability to different user needs and gait phases is insufficient
Solution Approach 1:
The patent implements variable stiffness mechanisms that allow the AFO to dynamically adjust its mechanical properties based on gait phase and user needs. The stiffness of the orthotic structure can be modified in real-time during the gait cycle, transitioning from rigid in stance phase to more compliant in swing phase, thereby resolving the contradiction between adaptability and device complexity.
Solution Approach 2:
The patent employs adjustable tensioning components and modular elements that enable changes in mechanical parameters such as stiffness, torque, and resistance levels. These parameter changes are achieved through adjustable connectors, variable resistance mechanisms, and reconfigurable structural elements, allowing the device to adapt to different therapeutic requirements without excessive complexity.
2Ease of operation
If AFOs lack adjustable stiffness mechanisms, then ease of operation is improved, but rehabilitation effectiveness and user mobility are limited
Solution Approach 1:
The patent divides the AFO into modular segments with independent adjustment capabilities. Each module can be individually configured for specific functions such as ankle stabilization, knee support, or hip assistance. This segmentation allows therapists and users to easily adjust only the necessary portions of the device, maintaining ease of operation while significantly improving rehabilitation effectiveness through targeted support.
Solution Approach 2:
The patent incorporates self-adjusting mechanisms that allow users to modify the device settings based on their own feedback and therapeutic progress. Automatic sensors detect gait parameters and trigger corresponding stiffness or torque adjustments, enabling the device to serve itself and reducing the need for frequent manual recalibration by therapists, thus maintaining ease of operation while enhancing rehabilitation outcomes.
3Adaptability or versatility
If AFOs do not integrate sensors and intelligence, then device complexity is reduced, but ability to provide intelligent adjustments based on user data is lost
Solution Approach 1:
The patent integrates sensors that continuously monitor gait parameters, joint angles, forces, and user motion. This feedback is processed by control systems that automatically adjust the mechanical properties of the AFO in real-time, creating a closed-loop system. The feedback mechanism enables intelligent adaptations to changing user needs and gait conditions while managing device complexity through efficient sensor integration and control algorithms.
Solution Approach 2:
The patent replaces purely mechanical adjustment systems with intelligent control systems that use sensors, microprocessors, and actuators. This substitution enables automated stiffness and torque adjustments based on real-time gait analysis, providing adaptive rehabilitation assistance without requiring complex manual mechanical mechanisms. The electronic control system manages complexity more efficiently than equivalent mechanical adjustment systems.
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
Enables self-calibration and customization of joint support, improving user mobility and rehabilitation effectiveness through adjustable stiffness and intelligent feedback.
Implementation Method 1
a tensioning component like a spring can store energy during a portion of the ankle rotation, and then the energy as assistive torque when the rotation is reversed
Implementation Method 2
AFOs with adjustable tensioning components, modular design, and integrated sensors for differential and variable stiffness, allowing manual or automated adjustments based on user data to provide assistive or resistive torque
Data Source
AI summary
An assistive ankle foot orthosis is described. The AFO has a vertical shank member arranged laterally to a user's limb. The member carries a rotational bearing and a rotational element such as a pulley. The rotational bearing is lateral to a user's ankle. The pulley is connected to a footplate. The footplate can be actuated to provide joint movement assistance or resistance to the user upon rotation of the pulley. The AFO includes an ankle angle and angular velocity sensor and a pressure sensor located under the user's forefoot. The AFO includes a controller that computes an estimate of the user's peak joint power on the basis of a series of products of measurements of foot pressure and angular velocity.