Prosthetic Knee Joint Control Using Inertial Angle Sensing
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Solution Overview
Problem
Existing artificial orthotic and prosthetic knee joints face challenges in achieving reliable and comfortable walking behavior due to complex control systems and high development times, as they struggle to effectively manage varying movement situations with simple rules.
Innovation Solution
A method that uses inertial sensors to determine the absolute angle of the lower leg component, compares it with threshold values, and adjusts bending resistance accordingly, allowing for a simple and reliable control of resistance devices, specifically reducing resistance during the swing phase and increasing it during the standing phase, with optional emergency modes for safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If state machines with multiple sensors are used to control actuators and brakes, then the control accuracy for various movement situations 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 multiple sensor requirements from the system. Instead of using multiple sensors (torque, force, angle) with elaborate processing, the invention uses a single angle sensor to detect swing phase initiation and triggers a simple control rule: reduce bending resistance when swing phase is detected. This extraction of essential function resolves the contradiction by maintaining adequate control accuracy while dramatically reducing device complexity.
Solution Approach 2:
The patent replaces expensive, complex mechatronic control systems with a simple, economical solution using basic angle sensing and resistance adjustment. The control mechanism uses inexpensive angle sensors and simple resistance devices rather than costly actuators and brakes with complex state machine logic, achieving acceptable control accuracy at much lower complexity and cost.
2Measurement precision
If multiple sensors detecting torque, force and angle are used with elaborate processing, then the measurement precision is improved, but the development time and complexity increase
Solution Approach 1:
The patent extracts only the essential measurement function (angle detection) from the complex multi-sensor system. By eliminating torque and force sensors and their elaborate processing requirements, the invention achieves sufficient measurement precision for swing phase detection while dramatically reducing development time and complexity.
3Device complexity
If simple rules are used to control the knee joint, then the device complexity is reduced, but the ability to encompass various movement situations is insufficient
Solution Approach 1:
The patent implements dynamic adaptability through real-time angle sensing and automatic resistance adjustment. The simple control rule dynamically responds to swing phase detection by reducing bending resistance, allowing the system to adapt to various movement situations without complex pre-programmed state machines. The dynamic nature of the angle-based detection enables versatility while maintaining simplicity.
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
This approach enables a smooth gait by adapting damping curves to individual patients, reducing development complexity and costs, while ensuring safety through adjustable threshold values and emergency resistance settings, thus providing reliable and effective support during walking.
Implementation Method 1
the absolute angle of the lower leg component is determined exclusively by means of at least one inertial sensor
Implementation Method 2
the absolute angle of the lower leg component is determined exclusively by means of at least one inertial sensor
Data Source
AI summary
The invention relates to a method for controlling an artificial orthotic or prosthetic knee joint, on which a lower leg component is arranged and which is assigned a resistance device having at least one actuator, by means of which the bending resistance is modified depending on sensor data that is determined during use of the orthotic or prosthetic knee joint by means of a sensor, wherein the absolute angle of the lower leg component is determined exclusively by means of at least one inertial sensor, the angle determined is compared with at least one threshold value, and the bending Resistance is modified when the threshold value is reached.