A novel hip exoskeleton with six degrees of freedom (DoF) was developed, and multiple prototypes of this product were created in this thesis. The device was an upper level of the 12-DoF lower-body exoskeleton project, which was known as the Orthotic Lower-body Locomotion Exoskeleton (OLL-E). The hip exoskeleton had three motions per leg, which were roll, yaw, and pitch. Currently, the sufferers of hemiplegia and paraplegia can be addressed by using a wheelchair or operating an exoskeleton with aids for balancing. The motivation of the exoskeleton project was to allow paraplegic patients to walk without using aids such as a walker or crutches. In mechanical design, the hip exoskeleton was developed to mimic the behavior of a healthy person closely.
The hip exoskeleton will be fully powered by a custom linear actuator for each joint. To date, there are no exoskeleton products that are designed to have all of the hip joints powered. Thus, packaging of actuators was also involved in the mechanical design of the hip exoskeleton. As a result, the output torque and speed for the roll joint and yaw joint were calculated. Each hip joint was structurally designed with properly selected bearings, encoder, and hard stops. Their range of motions met desired requirements. In addition, a backpack assembly was designed for mounting the hardware, such as cooling pumps, radiators, and batteries. In the verification part, finite element analysis (FEA) was conducted to show the robustness of the structural design. For fit testing, three wearable prototypes were produced to verify design choices. As a result, the weight of the current hip exoskeleton was measured as 32.1 kg. / Master of Science / Currently, patients who suffer from paraplegia are commonly treated with wheelchairs. However, the drawbacks of using wheelchairs introduced new medical challenges. One of the medical issues is the decrease in bone density. To address these medical problems and increase the quality of life of patients, lower-body exoskeletons are produced to assist with walking. To date, most of the current exoskeleton products require aids for balancing patients’ walking, and they don’t have fully actuated joints at the hip. As for the hip exoskeleton introduced in this thesis, all of the hip joints will be powered. Also, this device was the upper design of the Orthotic Lower-body Locomotion Exoskeleton (OLL-E), which aimed to create a self-balancing exoskeleton with total 12 of lower-body joints powered. The final goal of OLL-E is to assist the patient to walk at normal human speed without using aids.
This thesis discusses the process of designing a hip exoskeleton, which starts from requirements development to modeling and prototype tests. The conservative calculations and assumptions made in this paper guided the structural design of the hip exoskeleton. The robustness of the structures was ensured with rigorous finite element analysis. In the end, wearable prototypes were produced to examine the fitting tests. Overall, this design of the hip exoskeleton provided critical references for the future development of the OLL-E.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/78751 |
| Date | 28 August 2017 |
| Creators | Li, Xiao |
| Contributors | Mechanical Engineering, Leonessa, Alexander, Asbeck, Alan T., Southward, Steve C. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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