Prosthetic Knee Control via Linear Acceleration Thresholds
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Solution Overview
Problem
Existing methods for controlling artificial orthotic or prosthetic knee joints are complex and require elaborate components, making it difficult to achieve a reliable gait pattern with minimal control outlay, often relying on force measurements and multiple sensors.
Innovation Solution
A method that uses simple sensors, such as knee angle and inertial sensors, to determine parameters like linear acceleration and absolute angle, allowing for the reduction of flexion resistance, thereby enabling a swing phase without the need for force measurements or complex state machines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechatronic knee joints use multiple sensors and state machines to control actuators and brakes, then the functionality and reliability of the knee joint is improved, but the device complexity and development time increase significantly
Solution Approach 1:
The patent extracts and eliminates the complex state machine control logic and elaborate force measurement components from the system. Instead, it uses a simplified control approach based on basic sensor data (acceleration, angle) to achieve reliable gait control without the need for complex computational models or multiple specialized sensors.
Solution Approach 2:
The patent replaces complex mechanical control systems (state machines, elaborate sensor arrays) with a simpler control methodology that uses basic inertial sensors and straightforward control logic. The control is achieved through direct interpretation of acceleration and angle data rather than through complex state machine transitions.
2Measurement precision
If force measurements and multiple sensors are used to control the knee joint, then the precision of movement detection is improved, but the quantity of components and manufacturing complexity increase
Solution Approach 1:
The patent makes the basic inertial sensors (acceleration sensors and angle sensors) perform multiple functions: detecting linear acceleration, determining absolute angle, identifying gait phase, and triggering appropriate resistance levels. This eliminates the need for specialized force sensors and multiple dedicated sensors for each function.
Solution Approach 2:
The system uses the naturally occurring movement data from basic inertial sensors to self-determine gait phase and control requirements without needing external force measurements or complex sensor arrays. The acceleration and angle data inherently contain the information needed for control decisions.
Data Source
AI summary
A method for controlling an artificial orthotic or prosthetic knee joint, on which a lower-leg component is arranged and with which a resistance device is associated, the bending resistance (R) of which resistance device is changed in dependence on sensor data that are determined by at least one sensor during the use of the orthotic or prosthetic knee joint, wherein a linear acceleration (aF) of the lower-leg component is determined, the determined linear acceleration (aF) is compared with at least one threshold value, and, if a threshold value of the linear acceleration (aF) of the lower-leg component is reached, the bending resistance (R) is changed.