EMG-Controlled Exoskeleton Joint for Load Bearing
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Solution Overview
Problem
Conventional powered exoskeletons cause user fatigue due to reliance on mechanical sensors and predictive algorithms that do not accurately mimic natural movement, leading to counteraction and increased exertion.
Innovation Solution
A load-bearing powered exoskeleton using electromyographic (EMG) control, where EMG sensors detect muscle contractions to generate data that instruct actuators to move exoskeleton joints before the user's joints move, eliminating the need for reactive or predictive systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical sensors are used to detect force applied by the individual, then the exoskeleton can determine when and how much force to apply, but the individual must exert force against the link before the exoskeleton applies its force, leading to fatigue
Solution Approach 1:
The EMG sensor detects muscle contraction signals before the muscle actually contracts and moves the joint. The controller receives these preliminary signals and activates the actuator in advance, so the exoskeleton applies force before the user's muscle contraction completes, eliminating the need for the user to exert force against a stationary link and reducing fatigue
2Extent of automation
If predictive algorithms are used to determine when and how much force to apply, then the exoskeleton can operate autonomously, but the algorithms do not sufficiently mimic natural movement, causing the individual to counteract against the exoskeleton movement, leading to fatigue
Solution Approach 1:
The patent replaces predictive algorithms with direct EMG sensor feedback. The EMG sensor captures the user's actual neuromuscular intent in real-time, and the controller translates these signals directly into actuator commands. This substitution ensures the exoskeleton responds to the user's genuine movement intentions rather than relying on algorithms that may not accurately predict natural movement patterns, thereby preventing counteraction and fatigue
3Speed
If the exoskeleton responds after the user's joint moves, then the control system can react to actual movement, but the response delay causes the user to exert additional force, increasing fatigue
Solution Approach 1:
The EMG sensor detects electrical signals from muscle contraction before the muscle physically contracts and moves the joint. This preliminary detection allows the controller to activate the actuator in advance, so the exoskeleton begins moving before the user's joint movement is complete. This eliminates the perception of delay and reduces the additional force the user would otherwise need to exert, thereby reducing fatigue
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 reduces user fatigue by allowing the exoskeleton to accurately mimic natural movements in real-time, minimizing resistance and enabling the carrying of heavier loads with less exertion.
Implementation Method 1
an electromyography (EMG) sensor generates EMG sensor data based on the muscle contraction
Data Source
AI summary
An exoskeleton joint for a load-bearing powered exoskeleton includes a first exoskeleton link supporting a weight of an external load being applied to the powered exoskeleton and a second exoskeleton link that transfers the weight of the external load to a support surface, i.e., to the ground. In response to a contraction of a muscle of a human user associated with the exoskeleton joint, an electromyography (EMG) sensor generates EMG sensor data based on the muscle contraction. A controller receives the EMG sensor data, determines an actuator command based on the EMG sensor data, and communicates the actuator command to an actuator associated with the exoskeleton joint. This has the advantage that the exoskeleton joint associated with the human user's joint can be instructed to move in response to contraction of the muscle of the human user before the muscle causes the human user's joint to actually move.