NEC SEMINAR SERIES
Speaker: Isabella McCollum
Advisor: Dr. Nathan Makowski
Abstract: Neuromuscular electrical stimulation applied to peripheral nerves is a strategy to enhance or enable walking function following spinal cord injury (SCI). Walking has been implemented with feedforward control to generate sequences of nonadaptive steps. The lack of adaptability in the stepping control limits reactions to destabilizing events, such as slips and trips while walking, increasing the risk of falls. To address this gap, I propose a control system that utilizes information about the individual’s stability during walking to detect destabilizations; the system would then adjust the stimulus parameters to reduce the likelihood of a fall. To investigate whether sensor signals can detect external perturbations, a neurotypical subject completed walking trials with and without perturbations. Pelvis pulls were applied during early stance to generate perturbations, and we recorded Center of Mass (CoM) dynamics from an optimal motion capture system and wearable inertial measurement unit (IMU) signals. Deviations between perturbed and unperturbed walking signals were quantified for planning a dynamic threshold-based detection method. We evaluated accuracy and detection latency for each signal type. Preliminary results indicate that rotational kinematics about the pelvis are the most accurate signals for perturbation detection achieving high true positives rates, low false positives, and a detection latency within 50 ms – a feasible time window for balance recovery. These results will be developed into a real-time controller to detect and respond to destabilizations during walking.