Touchscreens equipped with friction modulation can provide rich tactile feedback to their users. To date, there are no standard metrics to properly quantify the benefit brought by haptic feedback.The definition of such metrics is not straightforward since friction modulation technologies can be achieved by either ultrasonic waves or with electroadhesion. In addition, the output depends strongly on the user, both because of the mechanical behavior of the fingertip and personal tactile somatosensory capabilities. This paper proposes a method to evaluate and compare the performance of haptic tablets on an objective scale. The method first defines multiple metrics using physical measurements of friction and latency. The comparison is completed with metrics derived from information theory and based on pointing tasks performed by users. We evaluated the comparison method with two haptic devices, one based on ultrasonic friction modulation and the other based on electroadhesion. This work paves the way toward the definitions of standard specifications for haptic tablets, to establish benchmarks and guidelines for improving surface haptic devices.

翻译：配备摩擦调制技术的触摸屏能够为用户提供丰富的触觉反馈。然而，目前尚无标准指标来恰当量化触觉反馈带来的益处。此类指标的界定并非易事，因为摩擦调制技术可以通过超声波或电粘附两种方式实现。此外，输出效果很大程度上取决于用户个体差异，这既源于指尖的力学行为特征，也受到个人触觉体感能力的影响。本文提出了一种在客观尺度上评估和比较触觉平板性能的方法。该方法首先利用摩擦和延迟的物理测量定义多项指标，继而通过基于信息论且由用户完成的指向任务衍生出比较指标。我们采用两款触觉设备对该比较方法进行了验证，其中一款基于超声波摩擦调制技术，另一款基于电粘附技术。本项工作为定义触觉平板的标准规范铺平了道路，有助于建立表面触觉设备的基准测试和设计指南。