FES Ergometer Automatic Spasm Control via Torque Feedback
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Solution Overview
Problem
Spinal cord injured patients often experience muscle spasms during functional electrical stimulation (FES) therapy sessions, leading to time loss and reduced benefits, as current methods to minimize spasms are either labor-intensive, require trained therapists, or slow stimulation ramp-up, which may not be effective for occasional spasms.
Innovation Solution
A functional electrical stimulation device with an automatic spasm control system that continuously monitors torque and rate of change, adjusting electrical stimulation and motor assistance to prevent spasms, by comparing current levels to calculated maximums and reducing them when spasm onset is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If stimulation levels are increased quickly to maximize patient benefit, then productivity is improved, but muscle spasms occur more frequently
Solution Approach 1:
The system continuously monitors torque and rate of change during FES cycling sessions, using this feedback to detect early signs of muscle spasms. When spasm indicators are detected, the controller automatically adjusts stimulation parameters in real-time, allowing rapid stimulation ramp-up while preventing spasm occurrence through closed-loop control
Solution Approach 2:
The system dynamically adjusts stimulation levels and ramp-up rates based on real-time muscle response monitoring. Rather than using fixed slow ramp-up rates, the controller modulates stimulation parameters adaptively, increasing stimulation quickly when muscles tolerate it and slowing down only when spasm indicators appear, optimizing both productivity and comfort
2Reliability
If a therapist manually monitors and adjusts stimulation to prevent spasms, then spasm control is improved, but device complexity and operational requirements increase
Solution Approach 1:
The system performs self-monitoring and self-adjustment of stimulation parameters by automatically detecting muscle spasm indicators through torque monitoring and autonomously modifying FES delivery accordingly. This eliminates the need for therapist intervention in real-time spasm management, reducing operational complexity while maintaining high spasm control reliability
Solution Approach 2:
The system replaces the mechanical/manual therapist monitoring and adjustment process with an automated electronic control system that uses torque sensors and control algorithms to detect and respond to muscle spasms. This substitution of manual therapy with automated mechanical-electrical control reduces the need for specialized therapist training while maintaining effective spasm management
3Object-affected harmful factors
If stimulation ramp-up is slowed to accommodate patient muscles, then spasm occurrence is reduced, but productivity decreases
Solution Approach 1:
The system uses dynamic, adaptive ramp-up rates that adjust in real-time based on muscle response monitoring. Instead of uniformly slow ramp-up, the controller rapidly increases stimulation when muscles show good tolerance and automatically slows only when spasm indicators are detected, achieving both fast overall ramp-up and effective spasm prevention
Solution Approach 2:
The system performs preliminary monitoring of muscle response at each stage of stimulation ramp-up, detecting early signs of spasm before they fully develop. This allows the controller to take preliminary corrective action by adjusting stimulation parameters proactively, enabling faster overall ramp-up while preventing spasm occurrence
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 effectively reduces muscle spasms during FES therapy sessions, allowing for more efficient and effective treatment by automatically adjusting stimulation and motor assistance, thereby minimizing time loss and maximizing patient benefit.
Implementation Method 1
functional electrical stimulation leads attached to skin adhesive electrodes which deliver electrical stimulation to a patient's muscles
Implementation Method 2
a monitor which continuously monitors the torque required to rotate one or both of the left and right extremity supports
Data Source
AI summary
This invention controls stimulation levels and cycling cadence on an FES ergometer to minimize or prevent the occurrence of spasm in spinal cord injured or other neurologically impaired patients.