Saleem Muhammad Khurram, Yilmaz Cetin, Basdogan Cagatay
IEEE Trans Haptics. 2018 Oct-Dec;11(4):599-610. doi: 10.1109/TOH.2018.2830790. Epub 2018 Apr 27.
To render tactile cues on a touchscreen by friction modulation, it is important to understand how humans perceive a change in friction. In this study, we investigate the relations between perceived change in friction on an ultrasonically actuated touchscreen and parameters involved in contact between finger and its surface. We first estimate the perceptual thresholds to detect rising and falling friction while a finger is sliding on the touch surface. Then, we conduct intensity scaling experiments and investigate the effect of finger sliding velocity, normal force, and rise/fall time of vibration amplitude (transition time) on the perceived intensity of change in friction. In order to better understand the role of contact mechanics, we also look into the correlations between the perceived intensities of subjects and several parameters involved in contact. The results of our experiments show that the contrast and rate of change in tangential force were best correlated with the perceived intensity. The subjects perceived rising friction more strongly than falling friction, particularly at higher tangential force contrast. We argue that this is due to hysteresis and viscoelastic behavior of fingertip under tangential loading. The results also showed that transition time and normal force have significant effect on our tactile perception.
通过摩擦调制在触摸屏上呈现触觉线索时，了解人类如何感知摩擦力的变化非常重要。在本研究中，我们调查了在超声驱动的触摸屏上感知到的摩擦力变化与手指及其表面之间接触所涉及的参数之间的关系。我们首先估计在手指在触摸表面滑动时检测摩擦力上升和下降的感知阈值。然后，我们进行强度缩放实验，并研究手指滑动速度、法向力以及振动幅度的上升/下降时间（过渡时间）对感知到的摩擦力变化强度的影响。为了更好地理解接触力学的作用，我们还研究了受试者的感知强度与接触所涉及的几个参数之间的相关性。我们的实验结果表明，切向力的对比度和变化率与感知强度的相关性最好。受试者感知到上升的摩擦力比下降的摩擦力更强，特别是在较高的切向力对比度下。我们认为这是由于指尖在切向载荷下的滞后和粘弹性行为。结果还表明，过渡时间和法向力对我们的触觉感知有显著影响。
