Quantifying coordination in multiple DOF movement and its application to evaluating 6 DOF input devices

Study of computer input devices has primarily focused on trial completion time and target acquisition errors. To deepen our understanding of input devices, particularly those with high degrees of freedom (DOF), this paper explores device influence on the user's ability to coordinate controlled movements in a 3D interface. After reviewing various existing methods, a new measure of quantifying coordination in multiple degrees of freedom, based on movement efficiency, is proposed and applied to the evaluation of two 6 DOF devices: a free-moving position-control device and a desk-top rate-controlled hand controller. Results showed that while the users of the free moving device had shorter completion time than the users of an elastic rate controller, their movement trajectories were less coordinated. These new findings should better inform system designers on development and selection of input devices. Issues such as mental rotation and isomorphism vs. tools operation as means of computer input are also discussed.