Publikationen von Max Pfeiffer


  • MuscleIO: Muscle-Based Input and Output for Casual Notifications
    Tim Dünte, Justin Schulte, Max Pfeiffer and Michael Rohs
    Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies - IMWUT '18
    Receiving and reacting to notifications on mobile devices can be cumbersome. We propose MuscleIO, the use of electrical muscle stimulation (EMS) for notification output and electromyography (EMG) for reacting to notifications. Our approach provides a one-handed, eyes-free, and low-effort way of dealing with notifications. We built a prototype that interleaves muscle input and muscle output signals using the same electrodes. EMS and EMG alternate such that the EMG input signal is measured in the gaps of the EMS output signal, so voluntary muscle contraction is measured during muscle stimulation. Notifications are represented as EMS signals and are accepted or refused either by a directional or a time-based EMG response. A lab user study with 12 participants shows that the directional EMG response is superior to the time-based response in terms of reaction time, error rate, and user preference. Furthermore, the directional approach is the fastest and the most intuitive for users compared to a button-based smartwatch interface as a baseline.





  • Let Me Grab This : A Comparison of EMS and Vibration for Haptic Feedback in Free-Hand Interaction
    Max Pfeiffer, Stefan Schneegass, Florian Alt and Michael Rohs
    Augmented Human
    Free-hand interaction with large displays is getting more common, for example in public settings and exertion games. Adding haptic feedback offers the potential for more realis- tic and immersive experiences. While vibrotactile feedback is well known, electrical muscle stimulation (EMS) has not yet been explored in free-hand interaction with large displays. EMS offers a wide range of different strengths and qualities of haptic feedback. In this paper we first systematically inves- tigate the design space for haptic feedback. Second, we ex- perimentally explore differences between strengths of EMS and vibrotactile feedback. Third, based on the results, we evaluate EMS and vibrotactile feedback with regard to differ- ent virtual objects (soft, hard) and interaction with different gestures (touch, grasp, punch) in front of a large display. The results provide a basis for the design of haptic feedback that is appropriate for the given type of interaction and the material.
  • A Design Space for Electrical Muscle Stimulation Feedback for Free-Hand Interaction
    Max Pfeiffer, Stefan Schneegass, Florian Alt and Michael Rohs
    Workshop on Assistive Augmentation at CHI 2014
    Free-hand interaction becomes a common technique for interacting with large displays. At the same time, providing haptic feedback for free-hand interaction is still a challenge, particularly feedback with different characteristics (i.e., strengths, patterns) to convey particular information. We see electrical muscle stimulation (EMS) as a well-suited technology for providing haptic feedback in this domain. The characteristics of EMS can be used to assist users in learning, manipulating, and perceiving virtual objects. One of the core challenges is to understand these characteristics and how they can be applied. As a step in this direction, this paper presents a design space that identifies different aspects of using EMS for haptic feedback. The design space is meant as a basis for future research investigating how particular characteristics can be exploited to provide specific haptic feedback.




  • A multi-touch enabled steering wheel: exploring the design space
    Max Pfeiffer, Dagmar Kern, Johannes Schöning, Tanja Döring, Antonio Kroeger and Albrecht Schmidt
    CHI '10 Extended Abstracts on Human Factors in Computing Systems - CHI EA '10
    Cars offer an increasing number of infotainment systems as well as comfort functions that can be controlled by the driver. With our research we investigate new interaction techniques that aim to make it easier to interact with these systems while driving. In contrast to the standard approach of combining all functions into hierarchical menus controlled by a multifunctional controller or a touch screen we suggest to utilize the space on the steering wheel as additional interaction surface. In this paper we show the design challenges that arise for multi-touch interaction on a steering wheel. In particular we investigate how to deal with input and output while driving and hence rotating the wheel. We describe the details of a functional prototype of a multi-touch steering wheel that is based on FTIR and a projector, which was built to explore experimentally the user experience created. In an initial study with 12 participants we show that the approach has a general utility and that people can use gestures for controlling applications intuitively but have difficulties to imagine gestures to select applications.