Paper Reading #14: TeslaTouch

TeslaTouch: Electrovibration for Touch Surfaces


Authors - Olivier Bau, Ivan Poupyrev, Ali Israr, and Chris Harrison


Authors Bios - Olivier Bau is a researcher at Disney Research and received his PhD from INRIA Saclay.
Ivan Poupyrev has a PhD from Hiroshima University and currently works in interactive technologies at Disney Research.
Ali Israr has a PhD in mechanical engineering from Purdue University and specializes in haptics.
Chris Harrison is PhD student at Carnegie Mellon University and is a Microsoft Research PhD Fellow.


Venue - This paper was presented at the UIST '10 Proceedings of the 23rd annual ACM symposium on User interface software and technology.


Summary


Hypothesis - In this paper, the researchers note that current touch surfaces do not give users any kind of haptic feedback resulting in drops in efficiency when used. The researchers propose using electrovibration in conjunction with touch surfaces to create a new kind of interface capable of many different haptic interactions with users. The hypothesis is that this new interface, TeslaTouch, will lead to new feedback possibilities resulting in more efficient interactions with users and be easily added to existing hardware.


Content - TeslaTouch was implemented using diffusing illumination for touch recognition on a 3M Microtouch panel originally designed for capacitive touch. Current is applied to the panel by a standard sound card controlled by the Pure Data sound programming environment. Due to the interaction users will have with different voltages, the researchers note many of the safety procedures followed in designing the device such as the fact that electrovibration does not actually pass current through a user's body and a user is exposed to the same current given off by conventional capacitive touch surfaces.The researchers explain that their implementation approach is scalable and can be applied to almost any surface as electrodes can be clear and applied easily everywhere. When compared to mechanical means of feedback electrovibration has some noticeable advantages. Some advantages electrovibration has include being more salable for large interfaces, producing no noise when active, and being more reliable than physical parts. Simulations, like writing or painting, and rubbing interactions, for picture editing, are just some of the many applications electrovibration.


Methods - Studies were conducted to observe what users perceive when touching the TeslaTouch surface to validate its use as an effective form of feedback:
1) 10 participants were asked to touch the TeslaTouch in 4 different configurations and give their feedback reagarding their experiences. This study will help the researchers decide what settings to adjust to achieve certain textures.
2) The absolute detection thresholds were determined by 10 participants touching a screen split into 2 sections and determining which had a tactile stimulus. The stimulus would be randomly chosen from 5 frequencies and the participants' choices decided how much the intensity, dB, would change. If a user chose right the intensity decreased and vica versa if a user chose wrong but after so many trials the scale of the change decreased so as to narrow down the threshold.
3) The frequency and amplitude discrimination thresholds were calculated by 7 participants choosing the unique surface from a set of 3 that had a test stimuli and 2 identical reference stimuli with intensity of 15 dB higher than the absolute detection threshold.


Results - The results of the methods mentioned above will help with determining what bounds to use and what factors affect the feeling:
1) The low frequency settings were viewed as being rougher than the high frequency settings. Amplitude changes in the high frequency settings changed how smooth or "waxy" the surface the felt while amplitude changes in the low frequency settings affected the perceived stickiness the surface possessed. 
2) The absolute detection thresholds were found to be severely affected by the frequency levels although a reliable figure was found to use in the following tests.
3) While the discrimination threshold was kept constant, frequency was found to severely affect user perception with the lower frequencies resulting in far more JNDs than the higher frequencies. Amplitude was found to be independent of frequency resulting in clear results.


Conclusion - The researchers conclude by stating that they have shown that electrovibration is a viable option for touch feedback in the future and that the abstract nature of the technology will allow for many applications to be uniquely implemented with it.


Discussion


I think the researchers successfully proved their hypothesis that electrovibration is a viable form of feedback for touch interfaces. The most interesting part of this research to me is the abstract nature of the tool which, unlike physical vibration which can only be vibrated at different intensities, has the potential to be used in many different ways such as simulating stick surfaces as opposed to bumpy surfaces or waxy surfaces. I think this technology has a future in the mobile tablet industry if more research is put into it and people start using it as the appeal for a device that supports this would be very high among the public in my opinion.