Figure 1. Touchbugs on a multi-touch table. Touchbugs: Actuated Tangibles on Multi-Touch Tables Diana Nowacka¹, Karim Ladha¹, Nils Y. Hammerla¹, Daniel Jackson¹, Cassim Ladha¹, Enrico Rukzio², Patrick Olivier¹ ¹ Culture Lab, School of Computing Science, Newcastle University, Newcastle Upon Tyne, UK d.nowacka@ncl.ac.uk ² Ulm University, Ulm, Germany enrico.rukzio@uni-ulm.de ABSTRACT We present a novel approach to graspable interfaces using Touchbugs, actuated physical objects for interacting with interactive surface computing applications. Touchbugs are active tangibles that are able to move across surfaces by employing vibrating motors and can communicate with camera-based multi-touch surfaces using infrared LEDs. Touchbug’s embedded inertial sensors and computational capabilities open a new interaction space by providing autonomous capabilities for tangibles that allow goal directed behavior. Author Keywords User interface device; actuated tangibles; interactive tabletops. ACM Classification Keywords H.5.2 [Information Interfaces and presentation]: User Interfaces - Haptic I/O. INTRODUCTION Tangible user interfaces (TUI) combine the dynamic qualities typical of digital information representations with physical affordances, i.e. “properties of an object that determine how it can be used” [5]. TUIs, in combination with multi-touch tables, provide passive haptic feedback for hand gestures and are augmented by a physical model for visual feedback. This allows people to interact with the input devices in the same way they interact with everyday objects, applying real world skills without the need for training or instructions. The benefits of these user interfaces include the simultaneous reduction of cognitive load placed on users (while they interact with an application) and simplification of the interaction itself. In contexts that are likely to include cognitive overload, time pressure, or stress, this may improve performance and even encourage improvisation and exploration [1]. Actuated TUIs allow data to be connected to, and represented by, physical objects (e.g. dynamic data can be linked to dynamics of the objects). They also facilitate more engaging, playful interaction and afford the use of movement as an expressive output modality. To date, approaches to connect actuated tangible user interfaces with interactive surfaces either require complex modification to, or augmentation of, the interactive surface hardware [4, 6, 8] or use constrained and relatively cumbersome tangible artefacts [2, 7, 10]. For example, Madgets are tangibles containing small magnets that are actuated using an array of electromagnets [8] (yielding a rather discontinuous movement). Marshall et al. [4] facilitate smoother and more accurate motion in their Ultra-Tangibles by applying ultrasound-based air pressure waves to actuate small lightweight objects on an interactive surface. In the few existing actuated tangible systems the possibilities for interaction are limited as the systems are essentially comprised of lightweight passive objects that are manipulated by an external applied force (i.e. electromagnetic or air pressure). Other designs have sought to enhance tangibles with wheels [2, 7, 10]; although wheeled objects are not entirely appropriate for direct interaction on interactive surfaces (i.e. they are not very robust and expose moving parts). In this paper we present Touchbugs, an open source hardware and software framework for a novel actuated tangible technology [11]. Touchbugs are small tangibles that use directed bristles and vibration motors for actuation (giving them the ability to move independently). Their infrared LEDs allow multiple Touchbugs to both be spatially tracked (position and orientation) on optical multi- touch tables and to communicate information about their internal state to the table. Embedded inertial sensors, which capture displacement and orientation, provide rich opportunities for interaction design including direct physical manipulation, and symbolic and metaphorical Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. CHI 2013, April 27–May 2, 2013, Paris, France. Copyright © 2013 ACM 978-1-4503-1899-0/13/04...$15.00.