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Design of Low Profile, Modular Lower Extremity Exoskeletons


Studies have shown that walking for as little as 30 minutes of a day can improve overall health. However, more than 250,000 people in the United States are paralyzed due to spinal cord injuries (SCI), and can no longer walk without support. Most of the SCI patients rely on wheelchairs after their injuries, and suffer from secondary injuries caused by prolonged sitting. Moreover, the patients' reduced mobility often brings negative effects to their independence and social life.

The primary research objective is to develop practical and effective exoskeleton technology that enables paralyzed individuals to achieve mobility and gain independence in their daily lives. In this dissertation, I discuss designs of low profile and modular exoskeletons, with an emphasis on different design attributes that increase device usability.

A minimally-actuated medical exoskeleton was developed with powered hip joints and passive knee joints. The low profile actuation units used for this exoskeleton's hip actuation allowed the wearer to achieve propulsion and walk through narrow passageways. In fact, this exoskeleton became the first powered medical exoskeleton that weighs less than twenty pounds. This exoskeleton continued to evolve into a system with increased modularity that meets various user needs based on different physical conditions. The modular design allows easy customization via its versatile support level configurations for different individuals. As a part of this research, comprehensive user studies of these devices and the user interface were conducted to create a positive user experience and a comfortable link between the user and the exoskeleton.

Paralyzed patients who participated in this study corroborated that the compact and lightweight design of the system enhances their mobility and maneuverability. The modularity in design opens assistive opportunities to various people, such as the elderly and other people with intact mobility. I expect that assistive exoskeleton technology will continue to advance and enhance the quality of life for a wide spectrum of communities in our aging society.

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