Design of Mechanism and Control Strategies for Assistive Systems to Remedy the Decrease in Physical Strength of the Aged and the Disabled

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Many statistics show a growing aging population, as well as a decrease in the strength capabilities of individuals comprising the aging population. This research will explore control strategies for assistive exoskeletons to help remedy the loss of strength in aging individuals' upper-extremities, allowing this growing segment of the population (as well as the infirm and handicapped) to live more self-sufficient, productive lives. Most human assistive applications involve distinct phases, each with their own unique dynamics and certain/uncertain transitions between these phases. The device that is the subject of this research will be designed to allow for active changing of the mechanical dynamic characteristics. In addition, it will be integrated with an intelligent control strategy that adapts to each phase in order to ensure the performance and safety of the combined human-device system. Results from this research will transform the way assistive devices behave. This research involves several disciplines including mechanical design, control theory, and bioengineering. The multi-disciplinary nature will help develop leadership skills of the participants in the research and positively impact engineering education.Integration of design and control of human assistive systems is emphasized in this research. The control problem will be formulated from the viewpoint of a hybrid system. The research encompasses the segmentation of the dynamics of the human assistive system, the identification of transitions, and the development of control structures appropriate for each segment. With this research, the following knowledge will be transformed or advanced: 1) human musculoskeletal modeling, hybrid system modeling, and mode (phase) identification of variable dynamics in typical upper-extremity tasks; 2) design principles for assistive devices with variable dynamic characteristics suitable for sensing of and reactions to mode changes, including impulse-like dynamic changes; and 3) principles and means for synthesis and analysis of hybrid switching policies (guards) for assistive systems to ensure safety of the user. The integration of the hybrid system theory with practical assistive systems will be the key to advancing our understanding of dynamics in such physical human-robot interactions.