Stimulation time determination for lower limb FES by using gait event and a "delay"

Area of Science:

• Biomedical Engineering
• Rehabilitation Science
• Neuroscience

Background:

• Lower limb neuroprostheses, particularly drop foot stimulators, aid hemiplegic patient locomotion.
• Current fixed stimulus control can lead to uncoordinated limb movements during rehabilitation.
• Improved control strategies are needed for effective lower limb motor function rehabilitation.

Purpose of the Study:

• To investigate the reliability of stimulus onset determination using inertial measurement units (IMUs).
• To propose a dynamic control algorithm for neuroprosthetic stimulation based on gait events and walking speed.
• To enhance coordination during lower limb rehabilitation training.

Main Methods:

• Recorded surface electromyography (sEMG) from tibialis anterior and medial gastrocnemius muscles.
• Utilized inertial measurement units (IMUs) to capture gait data.
• Compared and analyzed various muscle activity onset detection methods.
• Developed a dynamic algorithm to determine the delay between heel strike and muscle activation, relating it to walking speed.

Main Results:

• Identified reliable methods for detecting muscle activity onset using IMU data.
• Established a dynamic 'Delay' time between heel strike and muscle activity onset.
• Determined the relationship between this dynamic delay and walking speed through data fitting.

Conclusions:

• IMUs offer a reliable method for stimulus onset determination in lower limb neuroprostheses.
• A dynamic control algorithm based on gait events and walking speed can improve rehabilitation outcomes.
• This approach enhances the coordination of limb movement during gait training for hemiplegic patients.