FES Ergometer Automatic Spasm Control via Torque Feedback
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Solution Overview
Problem
Current functional electrical stimulation (FES) systems for spinal cord injured patients often cause muscle spasms during therapy sessions, leading to time loss and reduced benefits, as existing methods to minimize spasms are either labor-intensive, require trained therapists, or slow stimulation ramp-up, which may not be practical or effective.
Innovation Solution
A device with automatic spasm control system that monitors torque and rate of change to adjust electrical stimulation and crank speed, reducing stimulation and speed when spasms are detected, and gradually increasing them when safe to prevent muscle tone escalation, using a controller connected to servo motors and skin adhesive electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If manual stretching of patient's legs is performed prior to riding, then muscle spasm is reduced, but labor intensity increases and time is lost
Solution Approach 1:
The system performs preliminary detection of muscle spasm conditions through torque monitoring before full stimulation begins. The controller detects early signs of spasm and preemptively adjusts stimulation parameters to prevent full spasm occurrence, eliminating the need for manual stretching preparation
Solution Approach 2:
The FES system automatically monitors its own operation through torque sensors and self-adjusts stimulation parameters to prevent muscle spasm. The system serves itself by detecting harmful conditions and correcting them without external intervention, replacing manual stretching with automated feedback control
2Object-affected harmful factors
If manual observation and intervention by therapist is used, then muscle spasm is controlled, but device complexity and operational requirements increase
Solution Approach 1:
The system implements continuous feedback control by monitoring torque during stimulation and automatically adjusting electrical stimulation parameters. The controller receives real-time torque data, detects spasm conditions, and self-corrects stimulation delivery, replacing manual therapist observation with automated feedback loops
Solution Approach 2:
The patent replaces the mechanical/manual system of therapist observation and intervention with an automated electronic control system. Torque sensors, controllers, and algorithms substitute for human sensory and motor functions, eliminating the need for trained therapist supervision while maintaining spasm control
3Object-affected harmful factors
If stimulation levels are increased slowly, then muscle spasm is reduced, but productivity and therapy efficiency decrease
Solution Approach 1:
The system dynamically adjusts stimulation parameters based on real-time muscle response rather than following a fixed slow ramp-up schedule. The controller modulates stimulation intensity, frequency, and duration according to detected torque feedback, allowing rapid stimulation increases when muscles tolerate them and slow increases when spasm risk is detected
Solution Approach 2:
The patent changes multiple stimulation parameters (intensity, pulse width, frequency, duration) based on detected muscle conditions. Rather than simply increasing intensity slowly, the system adjusts the full set of stimulation parameters according to real-time torque feedback, optimizing both spasm prevention and therapy efficiency
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 device effectively reduces muscle spasms during FES therapy sessions by automatically adjusting stimulation and speed, allowing for more efficient and beneficial therapy without the need for continuous therapist supervision, enabling faster ramp-up of stimulation when safe and accommodating muscle tone fluctuations.
Implementation Method 1
functional electrical stimulation leads attached to skin adhesive electrodes which deliver electrical stimulation to a patient's muscles
Implementation Method 2
the left extremity support is connected to a left extremity support servo motor and the right extremity support is connected to a right extremity support servo motor, wherein each of said right and left extremity support servo motors causes its respective extremity support to rotate about an axis
Implementation Method 3
a monitor which continuously monitors the torque required to rotate one or both of the left and right extremity supports
Data Source
Figure 1
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.