Performance enhancing mechanisms for human manipulation

The goal of this dissertation project was to develop and evaluate three novel mechanisms for assisting people in moving the upper extremity for three functionally important tasks.;The objective of the first mechanism was to improve steering of an automobile. This task is commonly affected in old age, but there currently exist few devices to assist in driving. We developed a novel passive, moving arm rest that can provide support to the arms when the hands are in the recommended grip positions behind a vehicle's steering wheel. We provide experimental evidence that this simple gravity-balancing mechanism can improve human performance and ergonomics in steering a car.;The second mechanism aimed at assisting movement exercise of the forearm and wrist, an important task for rehabilitation after stroke. Existing mechanisms are cumbersome and expensive or achieve lighter weight by using a reduced number of degrees-of-freedom. A novel parallel mechanism was designed that is capable of moving a person's wrist along most of its natural workspace. The design of the device was inspired by the kinematics of the bones in the human forearm itself. The prototype device was used in preliminary experiments for a novel movement training application with the Nintendo Wii.;The objective of the third mechanism was to assist in naturalistic movement exercise of the human arm, again an important task for rehabilitation after stroke. Existing arm exoskeletons suffer from limited backdriveability, high weight, reduced number of degrees-of-freedom and/or limited force generation capability. The novel parallel mechanism developed here is a modified version of the wrist/forearm mechanism. The device incorporates lightweight, high-force, mechanically grounded pneumatic actuators, along with a spring-based counterbalancing system to balance the weight of the robot. The resulting exoskeleton can apply substantial forces to the human arm across a wide range of joint movement, while remaining lightweight, matching or exceeding capabilities of existing arm exoskeletons. The orthosis was used in an experiment with unimpaired subjects to test the hypothesis that practicing integrated, multi joint movement will improve naturalistic movement ability more than practicing a matched amount of the isolated components of the integrated movement.