Mobility is considered a human right and enables freedom. Self-initiated mobility is imperative for development of physical, cognitive, visual, and sensory abilities, and independence. Engineers design technology to support humans’ many modes of mobility;​ whether that be walking, biking, crawling, or rolling (e.g., propelling a manual wheelchair, car, or powered wheelchair). For people with disabilities, technology that supports mobility includes surgical interventions, therapies, and mobility aids which facilitate independence and participation. This dissertation investigates the impact of a multitude of strategies designed to support mobility for individuals with disabilities.

One large population within the disability community are individuals with cerebral palsy (CP). CP is the result of a brain injury at or near the time of birth and impacts mobility. Due to the unique nature of brain injuries, individuals with CP have heterogeneous disabilities that limit mobility and function. Elevated energy consumption during walking is a leading complaint of children and adults with CP that impacts endurance and community involvement. The causal mechanisms underlying elevated energy consumption for individuals with CP is unknown. One proposed cause of elevated energy consumption is muscle spasticity:​ velocity dependent resistance to stretch. We found that while a surgical intervention -- selective dorsal rhizotomy (SDR) -- did reduce spasticity, it did not reduce energy consumption during walking. These results not only demonstrates that spasticity is not a cause of elevated energy in CP, but also have large clinical implications as elevated energy consumption is commonly used as a selection criterion for SDR and “more efficient” walking and greater endurance are advertised as benefits of SDR.

Despite advances in technology and design of many mainstream mobility devices (e.g., cars or bikes) over the past century, devices designed for individuals with disabilities have not seen this same level of innovation. This is due to a dearth of research in the field of mobility aid design. For example, despite ankle foot orthoses (AFOs) being the most ubiquitous mobility aid for individuals with CP, the basic design has not significantly changed and there are still many opportunities for improvement to support mobility. Using focus groups with individuals with CP and their caregivers who had experience with AFOs, we investigated the lived experiences of AFO provision, use, and impact. We found that AFOs can benefit mobility and independence. However, many challenges still exist that hinder AFO provision, including the confusing and lengthy provision process, the need for more education and information during provision, and AFO discomfort.

“Early” or on-time mobility aid provision for infants and toddlers with disabilities is quite variable and there is no consensus of what is best with two different camps:​ (1) wait and see and (2) support mobility with technology as soon as possible. For young children with CP, orthoses and walking aids are the two most common types of devices they receive first. Yet, we do not know when or how most children first get these devices or the developmental impacts for this specific age group. We used surveys and interviews with caregivers and clinicians about the provision process of first mobility aids for young children with CP. We found that there are specific challenges for the provision and use of first mobility aids including, 1) requiring an agreement among clinicians on the provision timing, 2) which devices to use first, and 3) providing more enriched education and training for families.

One under-explored but promising mode of first mobility for toddlers is powered mobility. Experiencing different postures is important for development in early years. Additionally, it has been proposed that using powered mobility in a standing posture can allow the child to have dual progression in mobility and body structure goals. However, the impacts of posture while engaging with and learning how to use powered mobility is unknown. Through an experimental study, we investigated how children with disabilities under the age of three engage with and learn to explore with powered mobility over four play visits in both seated and standing postures. We found that toddlers with a variety of disabilities or mobility delays were able to engage with the joystick and explore their environment in both postures. Each posture (seated and standing) had its own positive and negative impacts on joystick control, distance traveled, bodyweight support, and muscle activity. Specifically, in the standing posture participants had more joystick activations, traveled a shorter distance, loaded a similar amount of weight through their legs, and had greater muscle activity especially when driving (vs. stationary play). Our findings can motivate future investigations and device design to optimize posture and access to device control. Additionally, our results can guide how to best implement on-time powered mobility in clinical care, even as an intervention in a therapy setting.

The work in this dissertation contributes to the fields of mechanical engineering and rehabilitation engineering through a comprehensive investigation of different technologies that individuals use to support and enhance their mobility. I employ methods from engineering, biomechanics, rehabilitation science, and disability studies fields to holistically answer these questions to better understand and support mobility for individuals with disabilities. This work will enable improved mobility aid design, provision, and use for individuals with disabilities.