Evaluation of tracking performance using joystick manipulators that engage different arm workspaces

Robotic devices, especially those that are motivating, have shown a great deal of potential for use in upper-extremity stroke rehabilitation. The TheraJoy project aims at designing a cost efficient device for use in home therapy. This has involved altering a commercial force-reflecting joystick by lengthening the joystick shaft to encompass a larger range of horizontal motion, adding a vertical linkage system to add vertical arm movements, and adding springs to support the application of light passive and actuated forces. This system has been used in conjunction with specially designed software to study both assessment and therapeutic tasks. As the endpoint for each linkage moves in an arc that is nearly a plane, there is a need to generate expectations for tracking patterns for each manipulator. This study evaluates movements in able-bodied subjects for strategic tracking tasks. A key observation is that the non-dominant hand displays both longer reaction and movement times and also greater and more consistent deviations from straight-line paths over certain ranges and directions.