The Multimodal Approach of Rendering Soft Textures on Touch Displays

• Applicant: Professor Dr.-Ing. Ercan Altinsoy
• Subject Area: Human Factors, Ergonomics, Human-Machine Systems ; Acoustics
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 498783029

Touch devices are becoming one of the most significant accessory of our daily lives due to being capable of running numerous tasks and being portable as opposed to computers. Nowadays, they are easily accessible, cheap and programmable input tools being used at various electronic devices. However, increasing number of applications and software have begun including complicated and critical tasks, and these tasks have been mostly operated on displays based on only visual cues. However, for more reliable and comfortable human-display interaction, precise haptic feedback should be promptly implemented to touch displays. For instance, reproducing tactile texture sensation on displays has been an emerging topic in the haptic field. In the last decade, landmark studies introduced measurement-based rendering techniques that enabled creating realistic haptic textures by recording surface information. However, such methods inevitably blend perceptually redundant data with the necessary texture information. Therefore, the first goal of this study is to determine the perceptual limits of the tactile sensation so that necessary amount of information can be driven for creating plausible texture feeling on displays. This goal will be also investigated using auditory feedback due to the fact that perceiving a texture is a complex fusion process of tactile and auditory modalities. Previously, various studies showed the effect of auditory feedback on tactile texture perception. Thanks to this effect, the influence of auditory feedback on further tactile data simplification and augmenting the plausibility of vibrations will be evaluated. Another concern of this study arises from the fact that touch displays have been limited with tactile feedback due to their fixed glass surface as opposed to traditional kinesthetic devices. Lately, several studies introduced different implementation ideas of kinesthetic feedback on touch displays, and these studies validated their actuation mechanisms using only simple stiffness models. Apart from these kinesthetic displays, even traditional force feedback devices have been used to render soft materials using linear second-order stiffness model which is commonly used to replicate the dynamics in the environment. On the other hand, soft materials cannot be well-described using linear models due to their nonlinear viscoelastic properties. Because of this, precise softness effect may not be generated on any kinesthetic devices. Thus, the second goal of this study is to reproduce realistic softness effect corresponding to various soft materials on touch displays. This aim will be realized by investigating human stiffness sensation and various non-linear stiffness models to mimic softness response precisely avoiding unnecessary complex models producing unperceivable details. At the end of this study, perception-based multimodal soft texture rendering strategy will be established.

• DFG Programme: Research Grants