Vincenzo Giamundo and Dušan Fetih
Touch screen devices are integral part of our life (Lepp, Li et al. 2015). However, our current user experience is mainly based on visual and auditory feedbacks. For instance, if we consider the common action of writing a text on our smartphone, while writing, we can see the keyboard on the screen and even listen the sound of button pressing, but we cannot really feel it. De LaTorre (2010) defines the haptic as a mechanism which recreates the sense of touch by applying forces, vibrations, or motions to the user. According to this definition, some devices currently integrate low resolution haptic feedbacks such as the vibration for silent alerting.
The target for the next generation devices is to integrate a high definition haptic feedback. For high definition haptic it is meant a tactile feedback which is perceived as being realistic and has sufficient high fidelity for effective recognition. That can be, for instance, to recreate the tactile illusion (Hayward et al. 2004) that onscreen buttons press and release like a real keyboard.
The main goal of the Prototouch project is to exploit a simulation software for the virtual prototyping and optimisation of high resolution haptic displays. This will lead to a better understanding of the underlying design principles and hence to the development of future generation devices. The project involves several different expertise such as physics, psychophysics, tribology, neurophysiology, machine learning and mechanics.
The Centre for Computational Continuum Mechanics (C3M) is a R&D performing company specialised in the development of numerical frameworks. C3M is one of the main partners in the Prototouch project and it is the principal host for the fellows Vincenzo Giamundo and Dušan Fetih, ER3 and ESR6 respectively. C3M plays a fundamental role within the Prototouch project being involved, together with the Swansea University (UK), in the computer simulation and integration tasks. ER3 and ESR6 tasks include virtual simulations, inverse analysis and optimisation. The focus of the virtual simulation is on the usage of tactile displays, in particular the interaction between the finger pad sliding on the tactile display. The simulations are performed by applying modern techniques for automatic differentiation of finite element formulations (Korelc 2009) to the parametrised virtual tactile models. The simulations are highly complex due to the huge variability in the biological material parameters (Fung 1982) and highly computationally expensive. The material parameters are achieved by means of inverse analysis also involving simple in-house in-vivo testing.
The simulations include several scenarios: from the sliding on a fixed plane surface to the sliding on a surface having a tactile feedback (generated by either electro-vibration or ultrasonic vibration) or even the sliding on a surface with Braille dots. The results of the virtual simulations are complex data sets which are shared with the other Prototouch partners. For instance, the data results are analysed and correlated to the results from tribological, mechanical and neurophysical experimental testing, in order to understand the underlying factors governing the performance of tactile displays.
• Lepp, J. Li, J.E. Barkley, S. Salehi-Esfahani. 2015 “Exploring the relationships between college students' cell phone use, personality and leisure”. Computers in Human Behavior, 43 (0) (2015), pp. 210–219.
• Robles De La Torre, G. 2010 “International Society for Haptics: Haptic technology, an animated explanation”. Isfh.org.
• Korelc, J. 2009 “Automation of Primal and Sensitivity Analysis of Transient Coupled Problems.” Computational Mechanics, 44 (5): 631–49. doi:10.1007/s00466-009-0395-2.
• Fung, Y C. 1982. “Biomechanics. Mechanical Properties of Living Tissues.” Medical Physics. doi:10.1118/1.595186.