Methods such as vibratory sensory substitution have shown promise for providing prosthesis users with a sense of contact and have proved helpful in completing motor tasks. In this thesis, two experiments were conducted to determine whether vibratory cues could be useful in discriminating between sizes. In the first experiment, subjects were asked to grasp a series of hidden virtual blocks of varying sizes with vibrations on the fingertips as indication of contact and compare the size of consecutive boxes. Vibratory haptic feedback significantly increased the accuracy of size discrimination over objects with only visual indication of contact, though accuracy was not as great as for typical grasping tasks with physical blocks. In the second, subjects were asked to adjust their virtual finger position around a series of virtual boxes with vibratory feedback on the fingertips using either finger movement or EMG. It was found that EMG control allowed for significantly less accuracy in size discrimination, implying that, while proprioceptive feedback alone is not enough to determine size, direct kinesthetic information about finger position is still needed.
A passive and a powered ankle joint system is developed and fit to the field of prosthetics, specifically ankle joint replacement for able bodied gait. The general 1 DOF robotic joint designs are examined and the results from testing are discussed. Achievements in this area include the able bodied gait like behavior of passive systems for slow walking speeds. For higher walking speeds the powered ankle system is capable of adding the necessary energy to propel the user forward and remain similar to able bodied gait, effectively replacing the calf muscle. While running has not fully been achieved through past powered ankle devices the full power necessary is reached in this work for running and sprinting while achieving 4x’s power amplification through the powered ankle mechanism.
A theoretical approach to robotic joints is then analyzed in order to combine the advantages of both passive and powered systems. Energy methods are shown to provide a correct behavioral analysis of any robotic joint system. Manipulation of the energy curves and mechanism coupler curves allows real time joint behavioral adjustment. Such a powered joint can be adjusted to passively achieve desired behavior for different speeds and environmental needs. The effects on joint moment and stiffness from adjusting one type of mechanism is presented.
3D printing prosthetics for amputees is an innovative opportunity to provide a lower cost and customized alternative to current technologies. Companies, such as E-NABLE and YouBionic are developing myoelectric prosthetics, electrically powered terminal devices activated by electromyography (EMG), for transradial amputees. Prosthetics that are 3D printed are less expensive for juvenile use, more sustainable, and more accessible for those without insurance. Although they are typically not outfitted with the same complex grip patterns or durability of a traditional myoelectric prosthetic, they offer a sufficient durability (withstanding up to 150 N on average) and allow for new opportunities in prosthetic development. Devils Prosthetics, a student research and development group associated with Engineering Projects in Community Service (EPICS), has investigated the benefits and pitfalls of utilizing polyethylene terephthalate glycol (PETG) for 3D printing prosthetics as well as combining a MyoWare EMG sensor with machine learning for optimal control of the prosthetic.