Understanding the Biomechanics of Balance Perturbations & Movement Objectives: Estimating Step Width Variability Using Minimal IMU Sensors

Abstract

Movement is an essential part of life; by developing and learning to understand the biomechanics of movement, more advantageous assistive devices can be created in the future. Step width variability is a gait metric that can be used to understand balance, especially perturbed balance. Normalized balance, or a participant's survey results for the emphasis they placed on maintaining balance, is a metric used to understand a person's movement objective. Visual optical flow perturbations make a participant off-balanced to understand how the body responds to impaired balance. By understanding the biomechanics of perturbed balance through step width variability and normalized balance in “real world” scenarios, better assistive devices may be able to be developed to help people with balance impairments. However, it is hard to compute step width variability in “real world” scenarios without large and expensive motion capture lab setups. I developed a method to calculate step width variability from two IMU sensors (one on the pelvis and one of the foot) through average speed, yaw angle at heel strike, and trigonometry to estimate step width on the order of magnitude expected for these gait metrics. While this method was only able to be applied to data from one participant in a pilot study, my results demonstrate a method that may be used in further research, after further validation, to understand balance in “real world” context better and could open up cheaper and more accessible ways to estimate gait metrics to help develop assistive devices for balance impairments.