Fall accidents are one of the most serious problems leading to unintentional injuries and fatalities among older adults. However, it is difficult to assess individuals' fall risk and to determine who are at risk of falls and in need of fall interventions. Therefore, this study was motivated by a need to provide a cogent fall risk assessment strategy that may be conducive to various wireless platforms. It aimed at developing a fall risk assessment method for evaluating individuals' fall risk by providing diagnostic modalities associated with gait. In this study, a "determinants of gait" model was adopted to analyze gait characteristics and associate them with fall risk. As a proof of concept, this study concentrated on slip-induced falls and the slip initiation risks. Two important parameters of determinants of gait, i.e. the pelvic rotation and the knee flexion, were found to be associated with slip initiation severity. This relationship appeared to be capable of differentiating fallers and non-fallers within older adults, as well as differentiating normal walking conditions and constrained walking conditions. Furthermore, this study also leveraged portable wireless sensor techniques and investigated if miniature inertial measurement units could effectively measure the important parameters of determinants of gait, and therefore assess slip and fall risk. Results in this study suggested that pelvic rotation and knee flexion measured by the inertial measurement units can be used as a substitution of the traditional motion capture system and can assess slip and fall risk with fairly good accuracy. As a summary, findings of this study filled the knowledge gap about how critical gait characteristics can influence slip and fall risk, and demonstrated a new solution to assess slip and fall risk with low cost and high efficiency. / Ph. D.

People experiencing mobility deficiencies in their lower limbs caused by genetics, injuries, diseases, etc. struggle with their physical and mental health. The goal of this research is to design an exoskeleton that will connect the upper limb (e.g., arm extension) to the ankle joint during walking movements. We advanced the first prototype of the Workshare Upper Lower Limb (WULL) by only targeting the ankle joint as the lower limb component. We found that this change would have the biggest impact on an individual's walking movements. The benefit of this research will be found in answering the question: will harnessing the kinetic energy from a person's upper limb (e.g., arm extension or arm flexion) to transfer into the ankle joint for gait assistance reduce the lower limb muscle activation during walking movements? A series of experiments were run to test the efficacy of the wearable device. Six participants were fitted to the device and six electromyography (EMG) sensors to track the muscle activation during a comfortable walking pace. This gait analysis study used pressure insoles to calculate ground reaction forces and multiple IMUs to track the individuals' limbs and joints kinetic motion. The overall effectiveness of the device was explored based on the data collected in this study. This device decreased muscle activation of the gastrocnemii medialis and increased the anterior deltoid activation. These results support the goal of the experiment to utilize the upper limbs (anterior deltoid) to assist the lower limbs (ankle joint) during walking.