Community-based locomotor training post-stroke has shown improvements in independent ambulation by increasing dose, intensity, and specificity of walking practice. Robotic ankle exoskeletons hold the potential to facilitate continued rehabilitation at home, but understanding what aspects of the design are most relevant for successful translation to the community presents a challenge. Here, we design a portable rigid ankle exoskeleton to use as a research platform for investigating the effect of assistance on post-stroke gait during overground, community-based walking. We first test our device with stroke survivors and validate its potential for future community use. We then present a systematic method for quantifying power transmission losses at each transmission stage from the battery to the wearer, using data gathered from walking trials with healthy participants. Our evaluation method revealed inefficiencies in power transfer at the interface level, likely resulting from the compliance in the structural components of the system, which motivates future redesign considerations. Overall, our method provides a framework to identify and characterize the components that must be redesigned to lower exoskeleton weight and maximize performance.

Hemiparetic gait after stroke is typically asymmetric and energetically inefficient. A major contributor to walking deficits is impaired paretic ankle function. Impaired paretic ankle plantarflexion (PF) reduces forward propulsion symmetry and impaired paretic ankle dorsiflexion (DF) diminishes ground clearance during swing. We have developed soft wearable robots (soft exosuits) to assist paretic PF and DF during walking after stroke. Through experimental studies with poststroke patients, we have demonstrated that exosuits can improve forward propulsion symmetry and ground clearance in walking, ultimately reducing the metabolic cost of walking. This paper presents an optimized soft exosuit aimed at use in clinical gait training for patients poststroke. The optimized exosuit is lightweight, easy to don and doff, and capable of efficiently delivering mechanical assistance to the paretic ankle. This paper focuses on the optimized controller that can deliver well-timed consistent ankle assistance to patients. A preliminary study was performed using this exosuit with three poststroke patients with heterogeneous gait patterns. Results showed that compared to a previously published controller, more consistent assistive force profiles could be delivered to individuals poststroke while consuming 50% less electrical power. Additionally, a preliminary biomechanical assessment was performed during overground walking.