Schaab J A, Radwin R G, Vanderheiden G C, Hansen P K
University of Wisconsin, Madison 53706, USA.
Hum Factors. 1996 Sep;38(3):390-403. doi: 10.1518/001872096778702042.
We compared two gain measures: One, defined as angle/angle (A/A) gain, is the ratio between the angle subtended by displacement of the cursor and the corresponding angle of head extension/flexion or rotation. The alternative measure, defined as displacement/angle (D/A) gain, is the ratio between the linear displacement of the cursor on the screen and the corresponding angle of head extension/ flexion or rotation. A discrete target acquisition task using circular targets was used to compare control-display gain measures. Operator performance was evaluated for three viewing distances and three gain settings of each measure. Average movement time and root mean squared (RMS) cursor deviation from a straight line path increased as viewing distance increased for A/A gain settings 0.75 and 1.0. That no significant distance effect was observed for any of the D/A gain settings indicated that it might be more suitable to fix D/A gain rather than A/A gain for head-controlled computer input devices. Minimum movement time occurred for D/A gain settings of 0.5 cm/degree and 0.67 cm/degree. One explanation for the observed insensitivity of performance to changes in viewing distance with a fixed D/A gain may be that both angular head movement and the accompanying kinesthetic feedback do not change for a specified cursor displacement as viewing distance is changed.
一种定义为角度/角度（A/A）增益，即光标位移所对角度与头部伸展/屈曲或旋转相应角度之间的比率。另一种测量方法定义为位移/角度（D/A）增益，即屏幕上光标线性位移与头部伸展/屈曲或旋转相应角度之间的比率。使用圆形目标的离散目标获取任务来比较控制显示增益测量方法。针对三种观察距离和每种测量方法的三种增益设置评估了操作员的表现。对于A/A增益设置0.75和1.0，平均移动时间和光标偏离直线路径的均方根（RMS）随着观察距离的增加而增加。对于任何D/A增益设置均未观察到显著的距离效应，这表明对于头部控制的计算机输入设备，固定D/A增益可能比A/A增益更合适。D/A增益设置为0.5厘米/度和0.67厘米/度时出现了最小移动时间。对于固定的D/A增益，观察到的性能对观察距离变化不敏感的一种解释可能是，随着观察距离的改变，对于指定的光标位移，头部角度运动和伴随的心因性反馈都不会改变。
