Towards local reflexive control of a powered transfemoral prosthesis for robust amputee push and trip recovery

Abstract

Transfemoral amputees often suffer from falls and
a fear of falling that leads to a decreased quality of life.
Existing control strategies for powered knee-ankle prostheses
demonstrate only limited ability to react to disturbances that
induce falls such as trips, slips, and obstacles. In contrast,
prior work on neuromuscular modeling of human locomotion
suggests that control strategies based on local reflexes exhibit
robustness to unobserved terrain such as slopes and steps.
Therefore, we propose that a powered knee-ankle prosthesis
governed by reflexive local controls will more competently adapt
to unperceived disturbances. To test this hypothesis, we simulate
a neuromuscular model of a transfemoral amputee walking over
rough ground with a powered knee-ankle prosthesis governed
by the proposed reflexive controller. We show that the proposed
control allows the amputee to walk farther over rough ground
than does the state-of-the-art control. The proposed controller
also more readily rejects deviations from nominal walking gaits
such as those encountered during a trip. These results suggest
that applying the proposed control to a powered knee-ankle
prosthesis will substantially improve amputee gait stability.