Measuring the allocation of control in 6 degree of freedom human-computer interaction tasks

Trajectory information can be analysed in both the time and space dimensions via a new metric called the $M$-metric. The $M$-metric is a measurement definition which quantifies the allocation of control across multiple degrees of freedom. Allocation of control is defined as the product of two components, the simultaneity of control and the efficiency of control, corresponding to the time and space dimensions respectively. The existing human factors, biomedical, and motor control literature serves as the foundation for the development of the $M$-metric. The $M$-metric has several limitations including dependency upon the chosen coordinate system, assumptions of optimal trajectories, and the lack of frequency domain analysis.; A six degree of freedom longitudinal virtual docking task experiment tested the $M$-metric's validity and usefulness. Results from the docking experiment showed that operators, rather than controlling all six degrees of freedom equally, allocate their control to the rotation and translation degrees of freedom separately, and switch control between the two groups. This switching of control is also a function of the input device and the allocation of control across all available degrees of freedom increases with practice.; Unlike a docking task, a tracking task specifies the time-space components of the required trajectory. A six degree of freedom longitudinal virtual tracking experiment was conducted to confirm the validity of the previous findings. Even under the conditions where equal allocation of control across all the degrees of freedom is required by the task, subjects in the tracking experiment still showed a preference to switch control between the translation and rotation degrees of freedom, though not as high as in the docking experiment.; Potential applications of the $M$-metric include evaluation of input devices, understanding of human motor control systems, and assessing neurological damage. To lay the groundwork for testing the $M$-metric as a possible diagnostic tool the docking experiment was re-run with elderly subjects. While results from the docking experiment show that elderly subjects show lower overall performance scores, no differences were found in the patterns of allocation of control across degrees of freedom.