Meeting Abstract
This research compares healthy unilateral transtibial amputees utilizing passive-elastic foot-ankle prosthesis and control subjects walking at normalized dimensionless speeds to assess collision-based angles, a set of kinetic parameters that relate supporting ground reaction forces (GRFs) and center of mass (CoM) oscillations. The persons with amputees (PWAs) tested in this study demonstrate a unique condition characterized by a complete biological foot-ankle and a mechanically constrained prosthetic which influences the dynamics of the human walking gait. The study design tests our hypothesis that walking dynamics, especially during double stance, have the potential for higher costs of mechanical transport (CoTmech), as determined by collision-based analysis, due to changes in the step-to-step transition for subjects employing an unactuated, spring-driven passive foot-ankle prosthesis. Our approach looks to gauge the effectiveness of the passive devices in restoring walking gait dynamics and assesses the importance of the step-to-step transition. Our examination of the kinetic relationship of the subject’s CoM and GRFs of discrete footfalls reveals the cooperative effort of the opposing lower limbs that generate resultant forces that redirect the CoM in a mechanically efficient manner from one step to the next. The relationship we typify in this study proposes reduced CoTmech due to the step-to-step transition that would otherwise be higher if the two steps were not contemporaneous. The collision-based angle approach we present contrasts the traditional understandings of the walking gait as an out-of-phase exchange of potential and kinetic energy system to one that demonstrates reduction in the ratio of actual to potential collision costs of the system.
