Adaptive Flexion Resistance Control for Lower-Limb Prosthetic Knees
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for controlling prosthetic and orthotic knee joints fail to dynamically adjust flexion resistance during stance phase, leading to uncomfortable and inefficient gait behavior in varying gait situations.
Innovation Solution
An adjustable resistance device between the upper and lower parts of the knee joint adjusts flexion resistance based on sensor data, increasing resistance during early and middle stance phase to block or slow further flexion, with adjustments dependent on ground inclination and gait situation, allowing for a more natural and energy-efficient gait.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If flexion resistance is permanently set in the stance phase, then the control system is simple, but the gait behavior becomes uncomfortable and inefficient in varying gait situations
Solution Approach 1:
The patent applies dynamics by transitioning from a static, permanently set flexion resistance to a dynamic resistance that adapts in real-time during the stance phase. The control system continuously monitors gait phase and ground conditions, adjusting the flexion resistance of the artificial knee joint accordingly. This dynamic adjustment allows the system to provide optimal support during early stance while permitting natural flexion during late stance, resolving the contradiction between operational comfort and system simplicity.
Solution Approach 2:
The patent implements parameter changes by modifying the flexion resistance parameter based on detected gait conditions. The control system changes the resistance parameter from a fixed value to a time-varying value that depends on the gait phase (early vs. late stance) and ground conditions. This parameter adaptation enables the system to optimize gait comfort across different walking scenarios without requiring a completely complex control architecture.
2Stability of the object's composition
If flexion resistance is increased to block further flexion during early stance phase, then knee stability is improved, but excessive flexion blocking may occur in varying terrain conditions
Solution Approach 1:
The patent employs feedback mechanisms where sensors detect gait phase, knee angle, and ground conditions, and this information feeds back to the control system. The control system uses this feedback to intelligently adjust the flexion resistance, increasing it during early stance phase when stability is needed, and reducing it during late stance phase when natural flexion is desired. This feedback loop enables the system to maintain knee stability while adapting to varying terrain conditions.
Solution Approach 2:
The system dynamically adjusts flexion resistance based on real-time detection of gait phase and terrain conditions. During early stance phase on level ground, the resistance is increased to provide stability. When the system detects late stance phase or varying terrain conditions requiring greater flexion, the resistance is reduced accordingly. This dynamic behavior resolves the contradiction between providing knee stability and adapting to different terrain conditions.
3Ease of operation
If stance phase flexion is permitted to avoid direct force transmission to pelvis, then gait comfort is improved, but excessive flexion leads to inability to fully extend knee during stance phase
Solution Approach 1:
The patent applies periodic action by implementing time-varying flexion resistance that follows the periodic nature of the gait cycle. During early stance phase, higher resistance is applied to limit excessive flexion and ensure proper knee extension for efficient weight bearing. During late stance phase, the resistance is reduced to permit controlled flexion that maintains comfort without compromising extension capability. This periodic modulation of resistance resolves the contradiction between comfort and walking efficiency.
Solution Approach 2:
The system changes the flexion resistance parameter dynamically throughout the stance phase based on detected gait progression. In early stance, the parameter is set to higher values to prevent excessive flexion and ensure proper knee extension for efficient walking. In late stance, the parameter is reduced to allow comfortable flexion. This parameter modulation enables the system to balance gait comfort with walking efficiency.
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 method enables a comfortable and energy-saving gait by dynamically adjusting flexion resistance, preventing excessive knee flexion and allowing for smooth transitions between stance and swing phases, especially in varying terrain conditions.
Implementation Method 1
A conversion device is arranged between the two parts. During pivoting of the upper part relative to the lower part, mechanical energy from the relative movement is converted and stored at least in an energy storage device. The stored energy is fed back to the joint device with a time delay to support the pivoting of the upper and lower parts during the movement.
Implementation Method 2
In addition to the conversion device, a separate damper in the form of a hydraulic damper or pneumatic damper can be provided, which is adjustable so that the resistance during walking can be influenced both in the flexion direction and in the extension direction via the damper device.
Implementation Method 3
In addition to the conversion device, a separate damper in the form of a hydraulic damper or pneumatic damper can be provided, which is adjustable so that the resistance during walking can be influenced both in the flexion direction and in the extension direction via the damper device.
Data Source
Figure 1
Figure 2~3
Figure 4~5c
AI summary
The invention relates to a method for controlling a prosthesis or orthesis of the lower extremity, which prosthesis or orthesis comprises an upper part (10) and a lower part (20) that is connected to the upper part (20) via a knee joint (1) and is mounted so as to be pivotable relative to the upper part (10) about a joint pin (15); wherein an adjustable resistance device (40) is situated between the upper part (10) and the lower part (20), by means of which resistance device a flexion resistance (Rf) in an early and middle standing phase is modified, during walking, on the basis of sensor data, following initial heel contact up to the middle standing phase; wherein, following the initial heel contact, the flexion resistance (Rf) is increased to a value at which further flexion is blocked or at least slowed; wherein the progression over time of the flexion resistance increase and/or the maximum achievable flexion angle (Af) is modified on the basis of the inclination of the ground or a height difference (∆H) to be overcome.