Haptics for Tangible Interaction: A Vibro-Tactile Prototype Andrea Bianchi KAIST Daejeon, Korea andrea@kaist.ac.kr Ian Oakley MITI Funchal, Portugal ian@uma.pt Jong Keun Lee KAIST Daejeon, Korea mango@kaist.ac.kr Dong Soo Kwon KAIST Daejeon, Korea kwonds@kaist.ac.kr Vassilis Kostakos MITI Funchal, Portugal vk@uma.pt ABSTRACT Research on tangible interaction and digital haptics has rarely intertwined, despite the natural relationship between physicality and touch. This paper addresses this relatively unexplored domain by presenting the Haptic Wheel, a freestanding single-axis rotational controller incorporating vibro-tactile cues. In addition to describing the hardware and implementation, the paper discusses the potential application of the system for eyes-free interaction, password entry and as an active puck on a tabletop system. The paper suggests that systems with active haptic feedback have unexploited potential as tools for tangible interaction. Author Keywords Haptics, Tactons, Vibrotactile, Rotary controller ACM Classification Keywords H.5.2 User Interfaces: Haptic I/O General Terms: Design, Security INTRODUCTION Tangible interaction, despite its focus on physical manipulation, has had limited engagement with work on digital haptics, or touch feedback. Notable exceptions include some of the most striking tangible systems, such as Brave et al’s inTouch [2]. This point is reinforced by a recent survey of tangible interaction that identifies actuation as a challenging but underdeveloped aspect of the field [6]. This paper addresses this shortcoming by presenting the design and implementation of a haptic device suitable for use in a range of tangible systems. The device is a standalone, light-weight and low-cost rotational haptic controller, the Haptic Wheel. It is capable of delivering various tactons [3], or structured vibrotactile cues. A wheel was selected for development as it supports a rich natural interaction (turning) that can perform selections (e.g. at specific angles), navigation or control an analog property. This paper describes the hardware design, interaction techniques and applications to which this device (and the feedback paradigm it embodies) can add value, both as a standalone system and as one element of a larger tangible interface. RELATED WORK A number of authors have produced rotary haptic devices. Recent examples include the Haptic Dial [4] and SmartPuck [5]. Broadly similar in design, the former uses a DC motor to generate torque profiles (varying magnitude, direction, velocity and acceleration) for virtual prototyping of controls, while the latter uses smaller battery-powered stepper motors for a similar purpose. The Haptic dial is a fixed device, while the SmartPuck is standalone, mobile and intended for a tabletop UI. Commercial systems based on this concept also exist, such as the iDrive force-feedback dial co-developed by Immersion Corporation and BMW. What is common to these systems is a distinctive feedback paradigm based on the use of single degree of freedom end- effectors generating active rotational force-feedback. While clearly useful, this approach suffers the disadvantage that it is only capable of presenting cues to users in response to their interaction (in terms of movement or applied force). Quite simply, without a user’s active input, such a device has nothing to push against and is incapable of producing meaningful output. For example, such devices are not able to render passive cues indicating particular system states. The paper explores how vibro-tactile cues [3], implemented in the Haptic Wheel, could achieve this objective more readily in the context of a mobile rotary controller. THE HAPTIC WHEEL The Haptic Wheel (diameter 8 cm, height 7.3 cm) is an electromechanical dial capable of continuous revolutions both clockwise and anti-clockwise. Physically, it is a standalone handle resembling the rotary control of a safe which turns on a slim base. It integrates a rotary encoder to track its absolute orientation, a binary switch mounted on its top center (for selection input) and a low-cost eccentric vibration motor to generate haptic feedback in the form of vibro-tactile stimuli. The casing is composed of a physically separate housing and base both formed of Polyjet resin using a 3D printer. The housing and base are jointed together with a bearing to minimize the friction created as the former rotates on the latter. The result is a rugged- feeling device which rotates with a level, pleasant sensation of mild, smooth friction. There is no noticeable inertia. The electronics of the wheel include an Arduino Mini micro-controller (which manages the wheel’s input and output devices), a Bluetooth communication module, (which features an LED showing communication channel status), a lithium-ion battery and charging circuits. The micro-controller can be programmed by connecting the 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. TEI’11, January 22–26, 2011, Funchal, Portugal. Copyright 2011 ACM 978-1-4503-0478-8/11/01...$10.00. 283