Prosthetic Limb Control via Accelerometer Signal Processing
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Solution Overview
Problem
Conventional prosthetic and orthotic devices lack effective systems for real-time detection and control of limb motion, leading to movement instability, high energy expenditure, and gait deviations in users, especially during the swing stage where pressure sensors are ineffective.
Innovation Solution
A system comprising accelerometers and a processor with a filter and comparison module to analyze time series motion signals, identify limb-motion events, and adjust prosthetic or orthotic devices accordingly, enabling real-time control and prediction of gait phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensors are used to detect ground contact, then stance stage detection is improved, but swing stage detection capability deteriorates
Solution Approach 1:
The patent combines pressure sensors with accelerometers to create a hybrid sensing system. Pressure sensors detect ground contact events during stance stage, while accelerometers continuously monitor motion dynamics during both stance and swing stages. The controller integrates signals from both sensor types to achieve reliable gait phase detection across the entire gait cycle, including the swing stage where pressure sensors fail.
2Device complexity
If conventional passive prosthetic devices are used, then device simplicity is improved, but gait stability and energy efficiency deteriorate
Solution Approach 1:
The patent implements a closed-loop feedback control system where sensors continuously monitor gait phase and motion parameters, the controller processes this information to determine actual gait characteristics, and the actuator adjusts prosthetic joint parameters in real-time based on detected deviations from desired gait patterns. This feedback mechanism dynamically stabilizes gait and adapts to varying walking conditions.
Solution Approach 2:
The patent replaces passive mechanical prosthetic structures with an active controlled system. Instead of relying solely on fixed mechanical components, the system uses sensors to detect motion, a controller to process information and make decisions, and an actuator to actively adjust joint parameters. This substitution of passive mechanics with active control enables dynamic adaptation and improved gait stability.
3Device complexity
If basic controllers are used in prostheses, then device complexity is reduced, but adaptability to dynamic environmental conditions deteriorates
Solution Approach 1:
The patent implements dynamic control where the actuator continuously adjusts prosthetic joint parameters based on real-time gait phase detection and motion analysis. The system adapts to varying walking speeds, terrains, and user intentions by processing continuous sensor feedback and modifying control parameters dynamically. This enables the prosthetic to respond adaptively to changing environmental conditions and user needs throughout the gait cycle.
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 system provides accurate detection and control of limb motion, reducing energy expenditure and stabilizing gait by processing continuous motion signals during both stance and swing stages, thereby improving the functionality and usability of prosthetic and orthotic devices.
Implementation Method 1
at least one accelerometer configured to generate a time series of motion signals indicative of a movement of a device associated with a limb
Data Source
AI summary
Control systems and methods are disclosed for processing a time series of signals associated with the movement of a device associated with a limb. The time series of motion signals is filtered, such as thorough an autoregressive filter, and compared to stored data sets representing a limb-motion event and/or phase. In certain examples, a plurality of accelerometers generate the time series of motion signals based at least on acceleration measurements in three orthogonal directions and/or planes. The acceleration measurements may relate to the movement of an artificial limb, such as a prosthetic or orthotic device. Upon determining an event and/or phase of limb motion, the control system may trigger an actuator to appropriately adjust one or more prosthetic or orthotic joints.