Bio-Inspired Control of Soft Exosuits for Ankle Assistance in Healthy Individuals

Abstract

Over the past decade, soft exosuits have been developed to assist with human walking. This dissertation details my contributions to the field of wearable devices by presenting new designs and controls for ankle assistive soft exosuits to reduce the metabolic cost of walking and load carriage. First, exosuit controllers that are inspired by ankle power and moment patterns were developed, and the exosuit reduced the metabolic cost of loaded and unloaded walking by 15% and 23% compared to walking with the device unpowered. Also, a controller that can automatically tune the key assistance parameters by maximizing the positive augmentation power was developed. A multi-joint exosuit and the individualized ankle assistance reduced the metabolic cost of loaded walking by 15% compared to walking without the device. This dissertation also details an adaptive exosuit controller for walking on uneven surfaces. The human natural response to unanticipated steps on different bumps was experimentally investigated, and a controller that can adjust the assistance parameters in response to steps on mild uneven surfaces was developed. Lastly, the link between exosuit assistance and underlying muscle-tendon dynamics using new measurement techniques is discussed. A controller inspired by soleus concentric contraction using ultrasound was developed, which was shown to reduce the metabolic cost over different walking tasks. Also, a mobile ankle-only exosuit and a tensiometer were used to investigate the Achilles Tendon load during exo-assisted walking.