Human-Machine Interaction with Mobility Enhancing Soft Exosuits

Abstract:

Stroke is the major cause of disability in adults in the western world, often resulting in hemiparesis and severe mobility impairments. Recently, rigid exoskeletons have been introduced for clinic-based gait rehabilitation: these systems can apply high levels of assistance, but also introduce kinematic restrictions and significant additional mass to the patient. As such, these devices are well suited to patients with little to no residual mobility (e.g. patients with complete spinal cord injuries) but may not be appropriate for patients with some limited walking ability but who seek greater community reintegration. We propose an alternative to rigid exoskeletons, called exosuits: clothing-like, soft wearable robots that use textiles to generate forces in parallel with the human musculature. We believe that this new class of wearable robots will enable robotic neurorehabilitation across the continuum of care, beginning in clinic and transitioning to the community. These exosuits could be discreetly worn underneath clothing during community activities, and would be capable of producing both immediate effects as well as longer term therapeutic improvements in walking ability. We present our first prototype of soft exosuit for post-stroke patients which consists of a soft unilateral garment; a remote cable actuation unit; and a real-time interface to allow the clinician to tailor the timing and level of assistance to the needs of the patient. The suit actively assists the wearer during both ground clearance and forward propulsion, and contains an additional module for foot stabilization. To date we have conducted patient-in-the-loop study of the device with 5 chronic stroke participants and conducted over 200 hours of testing. Early testing results on the treadmill demonstrate a reduced metabolic cost of transport and improved stability compared to baseline conditions, as well as a perceived benefit in both stability and cognitive load as self-reported by study participants.