| The focus of this dissertation is on the design, virtual prototyping and physical realization of one-of-a-kind assistive devices that are physically coupled or attached to the human user. This class of articulated assistive devices called teletheses are designed to be passive. The intimate physical coupling enables their use as "extensions" powered by the remaining functional musculature of the partially disabled user.;The novel class of Coupled Serial Chains (CSC) mechanisms is used in the design of such teletheses. CSC mechanisms can be realized by physically coupling the various joint rotations of a serial chain robotic device using cable and pulley drives. The resulting devices retain the serial-chain configuration but have fewer degrees of freedom. Their simplicity makes them highly suitable for actuation and control of complex position-force tasks by human users. Task-specific customization of such CSC mechanisms is necessary to enhance task performance. This is accomplished by design in the framework of dimensional synthesis of mechanisms. The main contributions of this dissertation are: (1) A modular integrated design environment, combining tools from synthesis, simulation and optimization with visualization to aid early user-customization and rapid design realization. (2) Optimal design of planar and spatial single degree-of-freedom coupled serial chain (SDCSC) mechanisms for matching desired end-effector position and force task specifications by combining precision point synthesis with optimization.;Specifically, we highlight the systematic formulation and analytic solution of precision-point path synthesis equations for 2-link spatial SDCSC mechanisms; and the kinetostatic design of SDCSC mechanisms to trace desired end-effector trajectories while supporting arbitrary loads, with and without torsional springs at the revolute joints.;The method for developing one-of-a-kindproducts is illustrated with a case study of a user-customized head controlled feeding aid for quadriplegics. |
