Effect of Pressing Force on Perceived Vibrotactile Intensity in Stylus-mediated Interaction.

Vibration feedback is a widely used form of haptic feedback in stylus-mediated interaction with screens of mobile devices. To accurately and efficiently present haptic effects, it is important to investigate key design factors that influence vibrotactile perception. In this paper, we perform experiments using two actuators (linear resonant actuator and voice-coil actuator) to investigate the effect of pressing force on perceived intensity with various combinations of factors such as actuator orientation, frequency of the driving signals, baseline perceived intensity, and user's motion speed in the vibrotactile feedback of stylus-mediated interaction. The results show that in stationary condition when the actuator is placed with its long side perpendicular to the axis of the stylus, the larger the pressing force is, the weaker the perceived intensity is; when the actuator is placed with its long side parallel to the axis of the stylus, the perceived intensity increases slightly with increasing pressing force. Another experiment is conducted and shows that the perceived intensity is more uniform when the amplitude is dynamically changed with the variation of the pressing force. For the moving conditions, the changes in pressing force have almost no effect on the perceived intensity. The results provide knowledge about the perceived intensity of vibrations in the stylus-mediated vibrotactile rendering.