Transtibial Prosthesis Resistance Timing for Natural Gait
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Solution Overview
Problem
Existing lower leg prostheses often lack sufficient energy storage and release mechanisms at varying speeds, leading to unnatural gait patterns, particularly at higher speeds.
Innovation Solution
A method and prosthesis design where the resistance device adjusts its maximum resistance point based on user speed, shifting it forward in the stance phase to ensure adequate energy storage and release, mimicking natural movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the resistance device increases resistance continuously or suddenly to achieve maximum resistance, then energy storage in the spring element is improved, but the range of motion between lower leg element and foot element is reduced and movement becomes restricted
Solution Approach 1:
The patent applies dynamics by making the resistance device adjustable and controllable during the gait cycle. The resistance is not fixed but can be modified in real-time based on the phase of gait and user needs, allowing optimization between energy storage and range of motion. The control system adjusts resistance parameters dynamically to achieve desired performance characteristics at different stages of movement.
Solution Approach 2:
The patent changes physical parameters of the resistance device, specifically the resistance force magnitude and timing characteristics. By adjusting when maximum resistance is reached during the stance phase and how rapidly it increases, the system can balance energy storage requirements with maintaining adequate range of motion for natural gait patterns.
2Length of moving object
If the maximum resistance point is delayed in the stance phase, then range of motion is increased and movement is facilitated, but energy storage in the spring element is insufficient for natural movement at higher speeds
Solution Approach 1:
The patent applies preliminary action by advancing the maximum resistance point to occur earlier in the stance phase, particularly at higher speeds. This timing adjustment ensures that the spring element has sufficient time to store energy before toe-off, preventing energy deficiency while still maintaining adequate range of motion through controlled resistance application.
Solution Approach 2:
The system dynamically adjusts the timing of maximum resistance based on gait speed and phase. At higher speeds, maximum resistance occurs earlier to ensure adequate energy storage, while at slower speeds the timing can be delayed. This dynamic timing adjustment resolves the contradiction between range of motion and energy storage requirements.
3Stability of the object's composition
If the resistance device provides high resistance to stabilize the ankle joint during slow walking, then stability is improved, but the gait pattern becomes unnatural at higher speeds due to insufficient energy release
Solution Approach 1:
The patent applies dynamics by making resistance characteristics speed-dependent. During slow walking, higher resistance provides ankle stability, while at higher speeds the resistance timing and magnitude are adjusted to enable adequate energy storage and release for natural gait. The control system modifies resistance parameters in real-time based on detected gait speed and phase.
Solution Approach 2:
The system changes resistance parameters including magnitude, timing, and rate of application based on gait conditions. By adjusting these parameters according to speed and phase, the system maintains stability when needed while enabling natural energy-based gait patterns at higher speeds, resolving the contradiction between stability and gait naturalness.
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 prosthesis user's gait pattern to resemble natural movement by storing and releasing more energy at higher speeds, maintaining stability and reducing unnatural movements.
Implementation Method 1
This spring element is designed to deform elastically during the final phase of the gait cycle and release the stored energy at the end of the stance phase
Implementation Method 2
The resulting resistance to this movement depends on the viscosity of the hydraulic fluid, which in turn depends on the speed. Viscosity decreases with increasing speed, thus increasing flow resistance.
Data Source
Figure 1~3
AI summary
The invention relates to a method for controlling a transtibial prosthesis comprising a foot element, a transtibial element swivellably arranged thereon and an adjustable resistance device for applying a resistance against a swivelling of the foot element relative to the transtibial element, wherein, in the method: the speed of the forward movement of the user of the transtibial prosthesis is determined; a maximum time within the standing phase of the step cycle is determined from the determined speed; when the maximum time is reached, the resistance of the resistance device is increase to a maximum value, wherein the earlier maximum time is in the standing phase, the higher the determined speed.