Examination of Gait Disorders in Hemiparesis Patients Using Foot-Mounted Inertial Sensors

Gait analysis system constructed of foot-mounted inertial measurement units (IMUs) provides an effective way for estimating gait symmetry. Unfortunately, gait asymmetry may not be visible in a single (spatial or temporal) dimension, and the dual-foot data may be out of phase in the time axis. This paper aims to explore a symmetry analysis method to give a close examination of gait disorders in hemiparesis patients using inertial sensor-based technology. Zero velocity updates (ZUPT)-aided Inertial Navigation System (INS) algorithm is used to estimate foot movements over multiple strides, and the accumulated INS error is further bounded using an inequality-constrained Extended Kalman filter (EKF). Fréchet distance is adopted to align the time series, thereby yielding the symmetry index between dual-foot data. Experiments were conducted along a straight-line path, and both healthy subjects and hemiparesis patients are participated. Experimental results demonstrated that the symmetry analysis with Fréchet distance could reveal gait disorders in both spatial and temporal dimensions.