Automated vehicles (AVs) reached technological maturity and will soon arrive on streets as traffic participants.Human traffic participants such as drivers, pedestrians, or cyclists will be increasingly confronted with the presence of AVs within their environment, not necessarily knowing or understanding what to expect and how to interact with them.Although AVs are designed to act safely, effective interaction in mixed traffic scenarios will depend on successful communication, interaction, or even negotiation beyond static rules and regulations.Prosocial behavior, such as yielding one's right of way, will be needed to resolve unclear traffic situations or foster traffic flow.However, what are the characteristics of such prosocial behavior, and how to measure this not only for automated vehicles

One way to improve road safety for cyclists is the development of hazard notification systems. Instead of in field experiments, such systems could be tested in safe and more controlled simulated environments; however, their validity needs verification. We evaluated the validity of mixed reality (MR) simulation for bicycle support systems notifying of dooring hazards. In a mixed-design study (N=43) with environment type(MR/test track) as within and hazard notifications (with/without) as between factor, comparing subjective and objective measures across environments.

Although automated driving is becoming a more widespread technology, there is still a lack of understanding about how to best communicate information to drivers in the specific situation of automated parking. This mixed-method user study aimed to address this gap by evaluating the preferences of users for information about the vehicle’s behavior in automated parking and the impact on user experience and situation awareness. An explainable concept displayed as augmented visualizations in the vehicle’s windshield was prototyped and evaluated in a driving simulation study and a qualitative interview. N = 25 participants provided insights into the development of more effective and user-centered interface designs for automated parking. As a result, the explainable concept was preferred by the participants and led to a higher user experience and explainability. This work contributes to the design and evaluation of future automated parking systems and provides a step towards more user-friendly automated driving experiences.

The introduction of micro-mobility, such as e-scooters, brings new challenges. Nevertheless, these trend devices are spreading rapidly without a comprehensive study of their interactions with other road users. For example, many countries currently require drivers of e-scooters to signal turns by hand. In this work, we investigate whether e-scooter riders can do this without losing control and whether they perceive hand signals as safe enough to use in traffic. We have conducted two studies with 10 and 24 participants, respectively. Each participant was able to perform hand signals without apparent problems. We also observed an intensive training effect regarding the handling of e-scooters. Nevertheless, our results indicate that a considerable number of inexperienced riders will, outside the laboratory, turn without signs with the currently prevailing e-scooter designs and regulations due to uncertainties.

Testing and validation of automated driving functions represent major challenges for automobile manufacturers and other stakeholders. Simulation of automated driving functions in a virtual world has the potential to accelerate testing and improve the quality of the optimization process. Among the many challenges in the urban context, a critical problem cluster involves the safety impacts of automated driving functions on vulnerable road users (VRU). Virtual assessment of safety impacts requires validated models of VRU behavior, particularly behavior related to “failure modes” and reactions in critical situations. Among VRU, there is an especially urgent need for data and models to describe the dynamics and behavior of e-scooter riders. A recent study performed by our group under laboratory conditions has provided data with implications for e-scooter stability, in particular the impact of hand signals and rear blind spot checks. It turns out that even novice e-scooter riders can successfully learn to maintain stability while performing these tasks. To understand the details of maintaining stability, a more profound understanding of the dynamical modes of the e-scooter, including the control and guidance process performed by the rider, would be of great utility, particularly to address the problem of realistic e-scooter models for simulations. To this end, more comprehensive e-scooter testing environments with enhanced sensor technology should be developed.

Today’s developments in the automotive industry are moving towards automated driving. At the highest levels, the driver becomes the passenger, which presents a new challenge for human-computer interaction. People not only have to trust in the automated system but are also confronted with increased complexity, as it is often not clear what the automated vehicle is about to do. An ambient light display is one way to give the driver a clearer picture of the car’s intentions and to keep complexity low. We have examined the impact on trust and user experience in more detail using two concepts for an ambient light display. One design provides information about detected potential conflicts in the current trajectory. The other design also highlights the future trajectory. We implemented both concepts as virtual light bars at the bottom of the screens. We evaluated them in a fixed-base driving simulator with 18 participants against each other and a baseline condition without additional information. Our scenario is a fully automated journey (SAE Level 5) through a German town. Although the two concepts do not differ much from each other, only the display showing both information – possible conflicts and future driving route – provided a clear added value for the users.

Automated vehicles (AVs) introduce a new challenge to human-computer interaction (HCI): pedestrians are no longer able to communicate with human drivers. Hence, new HCI designs need to fill this gap. This work presents the implementation and comparison of different interaction concepts in virtual reality (VR). They were derived after an analysis of 28 works from research and industry, which were classified into five groups according to their complexity and the type of communication. We implemented one concept per group for a within-subject experiment in VR. For each concept, we varied if the AV is going to stop and how early it starts to activate its display. We observed effects on safety, trust, and user experience. A good concept displays information on the street, uses unambiguous signals (e.g., green lights) and has high visibility. Additional feedback, such as continuously showing the recognized pedestrian's location, seem to be unnecessary and may irritate.

As automated vehicles increase on public roads, research on communication with vulnerable road users (VRUs) becomes increasingly important. Recently, numerous solutions to tackle this problem have been presented. However, it is not clear whether such concepts fit the needs and requirements of future users. The aim of this work is to identify the requirements and expectations of users after real-life exposure with an automated vehicle. We conducted a field study (N=32) in a small town where an automated vehicle is in regular operation and collected both subjective (surveys, semi-structured interviews) and objective (video analysis) data. Results suggest that VRUs prefer rather simple forms of communication derived from well-established concepts like traffic signs, horns or indicators. Furthermore, we could identify important scenarios that have yet not been addressed, and our findings are in particular useful for the provision of automated vehicles in shared spaces.

Knowing the locations of spatially distributed objects is important in many different scenarios (e.g., driving a car and being aware of other road users). In particular, it is critical for preventing accidents with objects that come too close (e.g., cyclists or pedestrians). In this paper, we explore how peripheral cues can shift a user's attention towards spatially distributed out-of-view objects. We identify a suitable technique for visualization of these out-of-view objects and explore different cue designs to advance this technique to shift the user's attention. In a controlled lab study, we investigate non-animated peripheral cues with audio stimuli and animated peripheral cues without audio stimuli. Further, we looked into how user's identify out-of-view objects. Our results show that shifting the user's attention only takes about 0.86 seconds on average when animated stimuli are used, while shifting the attention with non-animated stimuli takes an average of 1.10 seconds.

While performing multiple competing tasks at the same time, e.g., when driving, assistant systems can be used to create cues to direct attention towards required information. However, poorly designed cues will interrupt or annoy users and affect their performance. Therefore, we aim to identify cues that are not missed and trigger a quick reaction without changing the primary task performance. We conducted a dual-task experiment in an anechoic chamber with LED-based stimuli that faded in or turned on abruptly and were placed in the periphery or front of a subject. Additionally, a white noise sound was triggered in a third of the trials. The primary task was to react to visual stimuli placed on a screen in front. We observed significant effects on the response times in the screen task when adding sound. Further, participants responded faster to LED stimuli when they faded in.

In the last decade, several in-vehicle light displays have been proposed. These displays inform drivers via light patterns that go beyond simple status indicators. In this literature survey, we present 21 works with their light displays and patterns. In addition, we summarize the common methods and results of these works. This work will help researchers and designers find a good starting point for looking into in-vehicle light displays. It may further foster discussions about best practices in the community.

Car navigation systems typically combine multiple output modalities; for example, GPS-based navigation aids show a real-time map, or feature spoken prompts indicating upcoming maneuvers. However, the drawback of graphical navigation displays is that drivers have to explicitly glance at them, which can distract from a situation on the road. To decrease driver distraction while driving with a navigation system, we explore the use of ambient light as a navigation aid in the car, in order to shift navigation aids to the periphery of human attention. We investigated this by conducting studies in a driving simulator, where we found that drivers spent significantly less time glancing at the ambient light navigation aid than on a GUI navigation display. Moreover, ambient light-based navigation was perceived to be easy to use and understand, and preferred over traditional GUI navigation displays. We discuss the implications of these outcomes on automotive personal navigation devices.

The number of assistance systems in cars has been increasing in recent years. While these systems are targeted at supporting the individual driver and his or her safety, they may though compete for the driver's attention, and may demand too much of the driver's cognitive resources. Based on the established multiple resource theory in recent years, the use of different multimodal displays has been investigated that give the driver attention while not overloading sensory channels. In our work, we are looking into peripheral light displays in means to present safety relevant information. In this paper, we present the results of an experiment in which a peripheral light display was used to show the distance to a closing vehicle. The display is an LED stripe, seamlessly integrated into the side door and the dashboard of the car. Two different light patterns were tested in an overtaking scenario in a driving simulator. One pattern encodes the expected time to collision to the left rear car by moving a light source towards the front left corner. The other pattern additionally adapts its brightness to a simplified model of the driver's certainty to get his or her attention in uncertain situations. In contrast to previous works, we did not focus on a warning system but on a decision aid system. We found that using the adaptive pattern led to faster decisions and therefore to a smaller probability of violating safety distances. We believe that this pattern is a good basis for patterns which are fine-tuned to individual drivers as well as better driver models.

In the recent years, several automotive manufacturers started to integrate ambient light displays into cars to increase drivers' comfort. Expanding their possible application areas, we propose a display that continuously informs the driver of the vehicle's as well as the environment's state. We studied this display in a lane change maneuver, in which a driver has to decide if he or she can change lane in front of a faster closing car or brake to keep a safe distance to a slower car in front. We present results of an experiment for light patterns that are based on results of a design workshop and definitions for lane change decision aid systems (LCDAS) of ISO 17387. Though we used ISO's definitions for the timings, our participants felt that status updates on the display came too late. In addition, the abrupt warnings, implemented in one of the tested patterns, led to worse performance of the participants. On the other hand, we observed that participants liked a continuous encoding of the time-to-collision (TTC) and observed a decrease in missed opportunities to overtake. Therefore, we argue that the defined limits for the warning levels are not well suited to support drivers during decision making in our scenario. Our contribution lies in a novel way of supporting drivers during lane change using an ambient in-vehicle light display. We showed that a continuous light pattern might help drivers in decision making, while more research has to be done to validate this.

Recent interest in the development of ambient light systems has initialized a new research area, where the number of ambient light systems is expected to increase in the next years. To support the development of future ambient light systems, we need clear, explicit, and structured design guidelines. In this paper we present an evaluation of light patterns in a controlled laboratory study with two complementary parts. In the first part, our aim was to reveal and analyze light patterns that encode different types of everyday information. In the second part, we verified the results from the first part by asking another group of participants about their understanding of information encoded with light. Together, our results allowed us to establish light patterns and guidelines for building new ambient light systems and applications in the future.

Music is a fundamental part of most cultures. Controlling music playback has commonly been used to demonstrate new interaction techniques and algorithm. In particular, controlling music playback has been used to demonstrate and evaluate gesture recognition algorithms. Previous work, however, used gestures that have been defined based on intuition, the developers' preferences, and the respective algorithm's capabilities. In this paper we propose a refined process for deriving gestures from constant user feedback. Along this process a set of free-hand gestures for controlling music playback is developed. The situational context is analyzed to shape the usage scenario and derive an initial set of necessary functions. In a successive user study the set of functions is validated. Furthermore, proposals for gestures are collected from the participants for each function. Two gesture sets containing static and dynamic gestures are derived and analyzed in a comparative evaluation. The evaluation shows that we developed an appropriate set of free-hand gestures for music playback. Our results indicate that the proposed process, that includes validation of each design decision, improves the final results.