Figure 1
Impairment-specific hip assistance (iHA) adopted for the two study groups. On the left, a double flexion assistive profile adopted for group A (i.e. subjects with knee hyperextension). On the right, an extension-flexion assistive profile adopted for group B (i.e. subjects with deficits in hip flexion/extension). Paretic hip angle (grey), measured by the APO onboard sensors (medians and percentiles—25th, 75th), and desired assistive torque profiles for two representative subjects are depicted. The hip angle is segmented at the max flexion angle (MFA) and normalized to stride duration. The desired assistive torque is computed as the sum of two Gaussian functions (light blue, light purple). The first Gaussian curve occurs during stance, the second during swing. For each Gaussian function, the following parameters can be tuned: phase (p1 and p2, i.e. % of the gait phase where the peak occurs), amplitude [a1 and a2 (N·m), i.e. amplitude of the Gaussian peak, which can be either positive (flexion) or negative (extension)] and duration of the assistance (d1 and d2, i.e. the width of the Gaussian function in % of the gait phase).
