Publikationen von Max Pfeiffer

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.

Electrical muscle stimulation (EMS) has been used successfully in HCI to generate force feedback and simple movements both in stationary and mobile settings. However, many natural limb movements require the coordinated actuation of multiple muscles. Off-the-shelf EMS devices are typically limited in their ability to generate fine-grained movements, because they only have a low number of channels and do not provide full control over the EMS parameters. More capable medical devices are not designed for mobile use or still have a lower number of channels and less control than is desirable for HCI research. In this paper we present the concept and a prototype of a 20-channel mobile EMS system that offers full control over the EMS parameters. We discuss the requirements of wearable multi-electrode EMS systems and present the design and technical evaluation of our prototype. We further outline several application scenarios and discuss safety and certification issues.

Electrical Muscle Stimulation (EMS) recently received considerable attention in the HCI community. By applying small signals to the user's body, different types of movement can be generated. These movements allow designers to create more meaningful and embodied haptic feedback compared to vibrotactile feedback. This advantage also comes with further technical and practical challenges which need to be tackled. These challenges include a fine grained calibration procedure and a close contact to the user's body at specific on-body locations. This tutorial gives an overview about current research projects, challenges, and opportunities to use EMS for providing rich embodied feedback followed by a hands on experience. The main goal of this tutorial is that participants get a basic understanding of how EMS works and how systems that are using EMS can be developed and evaluated.

The human body reveals emotional and bodily states through measurable signals, such as body language and electroencephalography. However, such manifestations are difficult to communicate to others remotely. We propose EmotionActuator, a proof-of-concept system to investigate the transmission of emotional states in which the recipient performs emotional gestures to understand and interpret the state of the sender.We call this kind of communication embodied emotional feedback, and present a prototype implementation. To realize our concept we chose four emotional states: amused, sad, angry, and neutral. We designed EmotionActuator through a series of studies to assess emotional classification via EEG, and create an EMS gesture set by comparing composed gestures from the literature to sign-language gestures. Through a final study with the end-to-end prototype interviews revealed that participants like implicit sharing of emotions and find the embodied output to be immersive, but want to have control over shared emotions and with whom. This work contributes a proof of concept system and set of design recommendations for designing embodied emotional feedback systems.

In mobile contexts guidance towards objects is usually done through the visual channel. Sometimes this channel is overloaded or not appropriate. A practicable form of haptic feedback is challenging. Electrical muscle stimulation (EMS) can generate mobile force feedback but has a number of drawbacks. For complex movements several muscles need to be actuated in concert and a feedback loop is necessary to control movements. We present an approach that only requires the actuation of six muscles with four pairs of electrodes to guide the index finger to a 2D point and let the user perform mid-air disambiguation gestures. In our user study participants found invisible, static target positions on top of a physical box with a mean 2D deviation of 1.44 cm from the intended target.

Electrical muscle stimulation (EMS) is a promising wearable haptic output technology as it can be miniaturized considerably and delivers a wide range of haptic output. However, prototyping EMS applications is challenging. It requires detailed knowledge and skills about hardware, software, and physiological characteristics. To simplify prototyping with EMS in mobile and wearable situations we present the Let Your Body Move toolkit. It consists of (1) a hardware control module with Bluetooth communication that uses off-the-shelf EMS devices as signal generators, (2) a simple communications protocol to connect mobile devices, and (3) a set of control applications as starting points for EMS prototyping. We describe EMS-specific parameters, electrode placements on the skin, and user calibration. The toolkit was evaluated in a workshop with 10 researchers in haptics. The results show that the toolkit allows to quickly generate non-trivial prototypes. The hardware schematics and software components are available as open source software.

Electromyography (EMG) and electrical muscle stimulation (EMS) are promising technologies for muscle sensing and actuation in wearable interfaces. The required electrodes can be manufactured to form a thin layer on the skin. We discuss requirements and approaches for EMG and EMS as on-skin technologies. In particular, we focus on fine-grained muscle sensing and actuation with an electrode grid on the lower arm. We discuss a prototype, scenarios, and open issues.

Electrical muscle stimulation (EMS) is a promising wearable haptic output technology as it can be miniaturized and delivers a wide range of tactile and force output. However, prototyping EMS applications is currently challenging and requires detailed knowledge about EMS. We present a toolkit that simplifies prototyping with EMS and serves as a starting point for experimentation and user studies. It consists of (1) a hardware control module that uses off-the-shelf EMS devices as safe signal generators, (2) a simple communication protocol, and (3) a set of control applications for prototyping. The interactivity allows hands-on experimentation with our sample control applications.

In this course, participants create their own prototypes using electrical-muscle stimulation. We provide a ready-to-use device and toolkit consisting of electrodes, microcontroller, and an off-the-shelve muscle stimulator that allows for programmatically actuating the user's muscles directly from mobile devices.

Haptic feedback allows leveraging other faculties such as proprioception instead of using the visual sense, which is often overloaded with traditional UIs. However, most haptic technologies have been away from the current trend in Human-Computer Interaction (HCI) which is miniaturization (eg, mobile, wearable). Therefore haptic techniques, such as force feedback, tend to stay inside labs. In fact, most haptic devices resist miniaturization because they require physical motors and mechanics which do not scale down easily. Researchers have proposed miniaturizing and simplifying haptic devices by using electrical-muscle stimulation as to actuate the muscles directly, rather than actuating through mechanics. Electrical muscle stimulation (EMS) uses a small current to elicit action on the motor fibers/nerves, causing an involuntary contraction on the user’s body.

Pedestrian navigation systems require users to perceive, interpret, and react to navigation information. This can tax cognition as navigation information competes with information from the real world. We propose actuated navigation, a new kind of pedestrian navigation in which the user does not need to attend to the navigation task at all. An actuation signal is directly sent to the human motor system to influence walking direction. To achieve this goal we stimulate the sartorius muscle using electrical muscle stimulation. The rotation occurs during the swing phase of the leg and can easily be counteracted. The user therefore stays in control. We discuss the properties of actuated navigation and present a lab study on identifying basic parameters of the technique as well as an outdoor study in a park. The results show that our approach changes a user's walking direction by about 16°/m on average and that the system can successfully steer users in a park with crowded areas, distractions, obstacles, and uneven ground.

Pointing is one of the most basic interaction methods for 3D user interfaces. Previous work has shown that visual feedback improves such actions. Here we investigate if electrical muscle stimulation (EMS) and vibration is beneficial for 3D virtual hand pointing. In our experiment we used a 3D version of a Fitts' task to compare visual feedback, EMS, vibration, with no feedback. The results demonstrate that both EMS and vibration provide reasonable addition to visual feedback. We also found good user acceptance for both technologies.

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.

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.

As displays in public space are augmented with sensors, such as the Kinect, they enable passersby to interact with the content on the screen. As of today, feedback on the user action in such environments is usually limited to the visual channel. However, we believe that more immediate and intense forms, in particular haptic feedback, do not only increase the user experience, but may also have a strong impact on user attention and memorization of the content encountered during the interaction. Haptic feedback can today be achieved through vibration on the mobile phone, which is strongly dependent on the location of the device. We envision that fabrics, such as underwear, can in the future be equipped with electrical muscle stimulation, thus providing a more natural and direct way of haptic feedback. In this demo we aim to showcase the potential of applying electrical muscle stimulation as direct haptic feedback during interaction in public spaces in the context of a Kinect-based game for public displays.

Enterprise Architecture Management (EAM) plays an important supporting role in IT management of organizations to align their IT infrastructure to actual business needs. This emerging research paper presents an approach to enable real-time monitoring and controlling of enterprise architectures. Therefore, we adapted the “control center” concept as applied in power plants or railway control plants. The contribution of this paper presents an architecture for real-time monitoring and controlling facilities for complex business application landscapes. The business software control center is designed to give a real-time view of instances of IT-supported business processes together with the currently involved software systems and services. Moreover, IT operators are supported by controlling centers to actively control the load of software services at the business function level and to control the flow of business process instances through the organization’s IT infrastructure.

Cars offer an increasing number of infotainment systems as well as comfort functions that can be controlled by the driver. In our research, we investigate new interaction techniques that aim to make it easier to interact with these systems while driving. We suggest utilizing the steering wheel as an additional interaction surface. In this paper, we present two user studies conducted with a working prototype of a multi-touch steering wheel. In the first, we developed a user-defined steering wheel gesture set, and in the second, we applied the identified gestures and compared their application to conventional user interaction with infotainment systems in terms of driver distraction. The main outcome was that driver's visual demand is reduced significantly by using gestural interaction on the multi-touch steering wheel.

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.

The use of public transport vehicles, such as trams, buses, and taxis as an advertising space is increasing since several years. However mainly the outside of the vehicles is used to show advertisements using paintings, foil or roofmounted displays. Nowadays, with advances in display technologies, small highresolution displays can be easily embedded in vehicles and be used for entertainment or advertising purposes. In this paper we introduce an interactive context-ware advertising system designed for cabs, which is targeted to offer context-aware information such as advertisements, points of interest, events, etc. during a cab ride. Additionally it is possible for advertisers to upload their contents and define areas where their advertisements should be shown.