Adjustable Damping Control for Passive Prosthetic Knee Joints
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Solution Overview
Problem
Conventional passive prosthetic knee joints are optimized for walking on level ground and struggle to accommodate the different damping requirements for climbing stairs, leading to unacceptably high loads and difficulty in balancing and positioning the prosthetic foot on steps.
Innovation Solution
A control mode for a passive prosthetic knee joint with adjustable damping in the direction of flexion, which detects a low-torque lift to lower flexion damping, allowing easier placement of the prosthetic foot on the next step, and increases damping during foot placement and hip-straightening phases to facilitate controlled movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive prosthetic knee joints are optimized for walking on level ground with specific damping characteristics, then walking performance is improved, but stair climbing performance deteriorates due to unacceptably high loads and inability to balance
Solution Approach 1:
The patent applies dynamics by making the damping characteristics of the prosthetic knee joint adjustable rather than fixed. The control unit modifies damping parameters in real-time based on detected movement patterns, enabling the joint to adapt between walking mode (level ground optimization) and stair-climbing mode (reduced flexion damping for easier foot placement). This dynamic adjustment resolves the contradiction by allowing the system to optimize for different tasks sequentially.
Solution Approach 2:
The patent implements parameter changes by varying the damping coefficients of the prosthetic knee joint based on the detected activity type. During stair climbing, the control unit reduces flexion damping to facilitate foot placement on steps, while during level ground walking, it maintains higher damping for stability. This parameter adaptation enables the same prosthetic joint to perform both functions effectively.
2Ease of operation
If low extension damping is used in conventional knee joint prostheses for walking on level ground, then walking ease is improved, but stair climbing causes abrupt extension and unacceptably high loads on the prosthesis wearer
Solution Approach 1:
The patent uses dynamics to adjust extension damping based on the detected activity. During stair climbing, the control unit increases extension damping to prevent abrupt knee extension and reduce the load on the user. During level ground walking, it maintains lower extension damping for ease of movement. This dynamic control allows the system to manage forces appropriately for each task.
Solution Approach 2:
The patent implements feedback by using sensors to detect the user's movement patterns and activity type, then using this information to adjust damping parameters. The control unit continuously monitors movement characteristics and modifies damping forces in response, creating a closed-loop system that adapts to prevent excessive loads during stair climbing while maintaining walking ease.
3Stability of the object's composition
If high flexion damping is used in swing phase control for walking on level ground, then stability is improved, but the prosthetic foot cannot reach the top face of the next step up when climbing stairs
Solution Approach 1:
The patent applies dynamics by making flexion damping adjustable during the swing phase based on detected activity. During stair climbing, the control unit reduces flexion damping to allow greater knee flexion and extend the reach of the prosthetic foot to the top face of the next step. During level ground walking, it maintains higher flexion damping for swing phase stability. This dynamic adjustment resolves the contradiction between stability and reach.
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 more natural and efficient climbing of stairs by adjusting damping levels to accommodate the unique demands of stair climbing, reducing load on the prosthetic wearer and improving balance and positioning of the prosthetic foot.
Implementation Method 1
the mass inertia of the prosthetic foot, results in a passive prosthetic knee joint angle which, by bringing forward the hip or by a corresponding extension through the force of gravity, is sufficient to negotiate the step edge and to position the prosthetic foot over the step
Implementation Method 2
a corresponding extension through the force of gravity, is sufficient to negotiate the step edge and to position the prosthetic foot over the step
Data Source
AI summary
Systems and methods for controlling a passive prosthetic knee joint with adjustable damping in the direction of flexion such that a prosthetic unit attached to the knee joint can be adapted for climbing stairs.