Student Competition (Technology Innovation) ID 1986855

Abstract

Up to 70% of individuals with spinal cord injury (SCI) experience shoulder injuries during their lifetime. Previous studies revealed a link between the risk of shoulder injury and propulsion-related kinetic and kinematic parameters that were measured using SMARTWheel or in-lab motion-capture systems. Despite their high accuracy, these systems are time and labour intensive and not commonly accessible. To develop and validate a portable and accessible method to estimate the duration of the push phase using a hand-mounted inertial measurement unit (IMU). Ten volunteers (7 males, 3 females, age: 28 ± 2 y.o.) consented to participate in the study. An IMU (3D acceleration and angular velocity, sampling frequency: 512 Hz) was attached to participant’s right hand while sitting on the instrumented wheelchair equipped with SMARTWheel (sampling frequency: 240 Hz). The SMARTWheel and IMU readouts were collected while participants were propelling the wheelchair. The peaks in the resultant acceleration and continuous wavelet transform coefficients obtained from IMU were used to identify the hand contact and release, and estimate the push phase duration. No significant differences (p-value = 0.97, 0.89, and 0.94, respectively) were observed between the parameters obtained for the hand contact and release instants and push duration estimated using IMU compared to SMARTWheel with mean errors (standard deviation) of 8.4 (15.2) ms, 3.8 (22.1) ms and −4.6 (24.6) ms, respectively. These findings support the validity of using IMU as a portable alternative to the in-lab systems to estimate the push phase duration of manual wheelchair users.