Arm Orthosis Body Mount

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atrc, assistive, technology, resource, center, mqp, arm, orthosis, body, mount, muscular, dystrophy, prosthetic


The goal of this project was to design a device to mount a powered arm orthosis onto the body of a person using a wheelchair. Mounting the device onto the body is necessary because the individual would be much less constrained than if the orthosis was mounted on the wheelchair. The target users are individuals with Muscular Dystrophy, a degenerative disease that affects the skeletal muscles of the body. These users lack sufficient muscle control in their arms. A mounting system for a powered arm orthosis would help with daily activities. The design team researched shoulder kinematics and met with an orthotist to determine the design specifications of the mounting system. Four prototypes were designed, built, and tested. These prototypes were made of scrap material and were fit to a body-form for testing purposes. Markers and two lasers were placed on each of the prototypes so the motion under loading conditions could be mapped and analyzed. The most important specification was stability. Stability is required of the body mount because it must align the orthosis properly with the user’s shoulder joint in order to function correctly. After testing the four prototypes, the final body mount was designed using the results of the tests. The final prototype was chosen based on optimal results of stability tests and deflection analysis of the prototype with an applied load. Detailed CAD models of the harness were constructed so that another group could analyze the models and build the device. Materials were selected for each of the components and an assembly procedure was developed so that the harness could be manufactured.