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- All Subjects: Exoskeleton
- Creators: Sugar, Thomas
- Creators: Aukes, Daniel
- Member of: Theses and Dissertations
The purpose of this project is to improve upon the passive ankle foot orthosis originally designed in the ASU’s Robotics and Intelligent Systems Laboratory (RISE Lab). This device utilizes springs positioned parallel to the user’s Achilles tendon which store energy to be released during the push off phase of the user’s gait cycle. Goals of the project are to improve the speed and reliability of the ratchet and pawl mechanism, design the device to fit a wider range of shoe sizes, and reduce the overall mass and size of the device. The resulting system is semi-passive and only utilizes a single solenoid to unlock the ratcheting mechanism when the spring’s potential force is required. The device created also utilizes constant force springs rather than traditional linear springs which allows for a more predictable level of force. A healthy user tested the device on a treadmill and surface electromyography (sEMG) sensors were placed on the user’s plantar flexor muscles to monitor potential reductions in muscular activity resulting from the assistance provided by the AFO device. The data demonstrates the robotic shoe was able to assist during the heel-off stage and reduced activation in the plantar flexor muscles was evident from the EMG data collected. As this is an ongoing research project, this thesis will also recommend possible design upgrades and changes to be made to the device in the future. These upgrades include utilizing a carbon fiber or lightweight plastic frame such as many of the traditional ankle foot-orthosis sold today and introducing a system to regulate the amount of spring force applied as a function of the force required at specific times of the heel off gait phase.
In nature, some animals have an exoskeleton that provides protection, strength, and stability to the organism, but in engineering, an exoskeleton refers to a device that augments or aids human ability. Since the 1890s, engineers have been designing exoskeletal devices, and conducting research into the possible uses of such devices. These bio-inspired mechanisms do not necessarily relate to a robotic device, though since the 1900s, robotic principles have been applied to the design of exoskeletons making their development a subfield in robotic research. There are different multiple types of exoskeletons that target different areas of the human body, and the targeted area depends on the need of the device. Usually, the devices are developed for medical or military usage; for this project, the focus is on medical development of an automated elbow joint to assist in rehabilitation. This project is being developed for therapeutic purposes in conjunction between Arizona State University and Mayo Clinic. Because of the nature of this project, I am responsible for the development of a lightweight brace that could be applied to the elbow joint that was designed by Dr. Kevin Hollander. In this project, my research centered on the use of the Wilmer orthosis brace design, and its possible application to the exoskeleton elbow being developed for Mayo Clinic. This brace is a lightweight solution that provides extra comfort to the user.