Prosthetic Limb Control Using Muscle Activation Sensing
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Solution Overview
Problem
Existing prosthetic control systems face challenges such as poor calibration, inaccurate response, and limited functional lifetime due to issues with pressure sensors and electromyography (EMG) sensors, which are prone to failure and variability from repeated use and perspiration.
Innovation Solution
A prosthetic control system comprising a sensor component, a control component, and an actuation component, where multiple force sensing resistors are used in a Wheatstone bridge configuration to accurately detect muscle activation and transmit signals for precise control of prosthetic devices, such as ankle joints, with sensors placed strategically to minimize noise and ensure reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If force sensing resistors are placed on the prosthetic foot to measure ground reaction forces, then ground reaction force measurement is achieved, but the sensors break or signal drifts over time due to repeated kinetic shock
Solution Approach 1:
The patent extracts the sensing function from the prosthetic foot area (where high kinetic shock occurs) and relocates it to the residual limb area. Force sensing resistors are placed on the residual limb to detect muscle activation forces, separating the measurement location from the high-stress ground contact zone, thereby preserving sensor durability while maintaining measurement capability.
Solution Approach 2:
The patent introduces the residual limb as an intermediary medium for force sensing. Instead of directly sensing ground reaction forces at the foot, the system uses muscle activation forces in the residual limb as a proxy signal, which correlates with intended movement but experiences less mechanical stress.
2Measurement precision
If EMG sensors are placed inside the prosthetic socket to determine muscle activation, then muscle activation detection is achieved, but the readings are highly variable due to perspiration and limb movement
Solution Approach 1:
The patent replaces the electrical/chemical EMG sensing method with a mechanical force sensing approach. Instead of measuring electrical signals from muscles through wet EMG sensors, the system uses force sensing resistors to directly measure mechanical forces exerted by muscle activation, which are less susceptible to degradation from perspiration and movement.
Solution Approach 2:
The patent changes the measurement parameter from electrical signal intensity (EMG) to mechanical force magnitude. By measuring the physical force exerted by muscles on the residual limb rather than electrical potentials, the system achieves more stable and reliable signals that are not degraded by moisture or movement artifacts.
3Measurement precision
If multiple sensors are used to improve control accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the control function by using multiple force sensing resistors placed at different locations on the residual limb (e.g., anterior, posterior, medial, lateral positions). Each sensor provides independent information about muscle activation in different regions, enabling differentiated control commands for various prosthetic functions while maintaining a relatively simple overall system architecture.
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 reliable and accurate control of prosthetic devices, enhancing wearer control and extending the functional lifetime by filtering noise and maintaining precise control over prosthetic movements, even under varying conditions like walking and standing.
Implementation Method 1
multiple force sensing resistors are used in a Wheatstone bridge configuration to accurately detect muscle activation and transmit signals
Implementation Method 2
force sensing resistors are used in a Wheatstone bridge configuration to accurately detect muscle activation
Data Source
AI summary
A system and method for controlling a prosthetic limb are provided. A sensor component receives input from a wearer's muscle and provides a signal to a control component. The sensor component may be a force sensing resistor placed inside a socket of a prosthetic limb between a residual limb and the hard side of the socket. The control component processes the signal and provides instructions to an actuation component. In this manner, an actuation component may move a joint, or may change the velocity of a joint, or may change other characteristics of the prosthetic limb.