Vibration-Based Surface Recognition for Smartphones

With various sensors in a smart phone, it is now possible to obtain information about a user and her surroundings, such as the location of a smartphone and the activity of the smartphone user, and the obtained context information is being used to provide new services to the users. In this paper, we propose VibePhone, which uses a built-in vibrator and accelerometer, for recognizing the type of surfaces contacted by a smart phone, enabling the sense of touch in smartphones. For humans and animals, the sense of touch is fundamental for both recognizing and learning the properties of objects. The sense of touch is obtained from the texture of an object and humans recognize the type of an object by scrubbing the surface with fingers. Since a smartphone cannot physically scrub the contacting surface, we emulate the touch by generating vibrations using a smartphone and propose a method to recognize the type of contacting objects. The recognition of the object type by vibration alone is an extremely difficult task, even for a human. However, we demonstrate that it is possible to distinguish object types into broad categories where a phone is usually placed, e.g., sofas, plastic tables, wooden tables, hands, backpacks, and pants pockets. The proposed VibePhone system achieves an accuracy over 85% on average. We have prototyped VibePhone on an Android-based smart phone which changes its background display based on the contacting surface. We envision that the haptic perception in future smart phones will enable new experiences to the users.