Effects of Mechanical Interventions on Human Locomotion

Abstract

Due to population ageing and increasing incidence of neurological disorders, the demand for robotic technologies for assisting, augmenting, and restoring human locomotion is rapidly increasing. Recent approaches aim to make the devices adaptive to improve performance and to deal with individual differences. When developing adaptive devices, however, it should be remarked that humans are also adaptive, and physical interaction with mechanical interventions may substantially change their behavior. To advance technologies for human locomotion, therefore, not only it is important to understand fundamentals of human locomotion itself, but also it is required to understand how human locomotion is altered by the mechanical interventions.

In this thesis, I aimed to understand and establish fundamentals of the effects of mechanical interventions on human locomotion. In the first part of the thesis, I characterized how human walking was changed with a powered hip exoskeleton robot and investigated its underlying principles. In the second part of the thesis, I quantified how human balance on a narrow beam was substantially and immediately changed by altering mechanical interface or using mechanical support (i.e., canes). Behavioral indicators of changes in central neural processes were investigated, which is critical to determine the potential of an intervention for rehabilitation or compensation. In the last part of the thesis, I developed methods to quantify human balance mechanisms during normal standing without applying perturbations which may evoke perturbation-dependent changes to the identified human behavior. Throughout this work, simple models were extensively used to design and interpret human experiments as well as to quantify human behaviors with a handful of parameters.