1st SCARline Workshop: On Operationalization of Driving Simulator Studies for Accessible In-Vehicle HMI Prototyping and Evaluation

Designing and evaluating in-vehicle Human-Machine Interfaces (HMI) is an inherently interdisciplinary challenge, sitting at the intersection of interaction design, software engineering, and empirical research methods. As vehicle automation continues to advance, the demand for researchers and designers capable of prototyping and evaluating in-cabin experiences in simulated environments has grown significantly [2, 4]. Driving simulators have become essential tools in this process, enabling controlled, repeatable studies without the cost and risk of real-world testing [11].

However, setting up and running a simulator-based user study remains a technically demanding undertaking. Researchers and designers must simultaneously manage simulator configuration, HMI prototyping, sensor integration, and study design, a combination that presents a steep learning curve even for experienced practitioners [6, 10]. This barrier is felt especially acutely by those without a deep technical background, a situation we observed directly in an automotive HMI course at Technische Hochschule Ingolstadt, where participants from diverse disciplinary backgrounds brought varying levels of programming experience, familiarity with research methods, and prior exposure to simulation environments [12, 13].

Recent efforts in the community have sought to address this gap by developing more accessible simulator frameworks. Platforms such as Skyline [2], SKYNIVI [1], and MRDrive [6] have each contributed to lowering the barrier to entry for simulator-based HMI research, offering varying degrees of abstraction and flexibility, while more recent platforms such as Sky-Drive [8] demonstrate the growing sophistication of simulation tools, albeit oriented primarily toward autonomous driving algorithm development rather than HMI research. This direction aligns with a broader movement in the community toward openness, transparency, and reproducibility in automotive user research [5]. A parallel trend among Automotive HCI researchers has been exploring virtual reality shared environments to explore the social construct of driving with multiple participants in different roles sharing a common simulation environment [3, 7, 9]. Among all these efforts a clear operationalization gap remains: most existing tools either require significant technical expertise to configure, focus primarily on autonomous driving rather than HMI research, or do not provide an integrated environment that simultaneously supports HMI design, sensor data collection, and study management from a single researcher-facing interface. This point was reinforced in an analysis of researcher painpoints that made clear that current research tools are not meeting the research needs with painpoints organized across several operationalization areas: difficulty programming NPCs, lack of adjustability of simulation parameters, complexity of integrating physical prototypes, insufficient support for AR/ VR capabilities and scene creation, inadequate API integration and limited standardization of driving simulators [10].

SCARline was developed in direct response to this gap. The platform sits on top of a driving simulator and abstracts away the technical complexity of the underlying infrastructure, allowing researchers and designers to focus on their research question, their study design, and the in-cabin interaction experience they want to create and evaluate. Rather than tying itself to a single simulator, SCARline introduces an abstraction layer that, in principle, allows different simulation backends to be connected over time.

A preliminary evaluation of an early low-fidelity version of SCARline with 9 participants from mixed disciplinary backgrounds provided initial validation of both the platform's potential and the areas requiring further development. Qualitative feedback highlighted the need for clearer onboarding, better mental models of the system, and more structured guidance during hands-on tasks, while participants nonetheless recognized the platform's value once its basic concepts were understood. Usability scores reflected the early stage of the prototype, with results expected to improve as the interface matures. This workshop represents the next step in that iterative process, bringing SCARline to the broader AutomotiveUI research community to gather expert feedback, stress-test the platform in a new context, and collectively discuss best practices for accessible simulator-based HMI research.

The primary goal of this workshop is to introduce SCARline to the automotive HMI research community and to collectively explore the challenges and opportunities of accessible simulator-based research tooling.

Participants will first gain a conceptual understanding of the problem SCARline addresses, namely the technical overhead that prevents researchers and designers from focusing on their core research questions when working with driving simulators. They will be walked through the physical and software architecture of the platform at a level sufficient to evaluate its applicability to their own research contexts, without requiring prior knowledge of simulator internals.

Participants will then gain hands-on experience designing and implementing an HMI widget, working in small groups to produce a functional interface element and observe it running live within the platform. Building on this, they will configure a simple but fully functional user study scenario directly within the simulator, experiencing the complete research pipeline that SCARline enables, from interface design through to study deployment and data collection.

Finally, the workshop will provide a structured space for discussion around the broader question of accessible and open HMI research tooling: what researchers need from such platforms, what current tools still leave unaddressed, and how platforms like SCARline could evolve to better serve the community. Feedback collected during this session will directly inform the continued development of SCARline.

The workshop is structured into five sessions across a half-day format of approximately 3 hours, combining short presentations with hands-on group activities.

Session 1: Introduction and Problem Framing (30 min). The workshop opens with a presentations from workshop organizers and invited researchers talking about operationalization issues in driving simulation studies, followed by a brief presentation introducing the motivation behind SCARline. Organizers will outline the challenges researchers and designers face when setting up simulator-based HMI studies, particularly those without a deep technical background, and contextualize SCARline within the broader landscape of existing simulator frameworks.

Session 2: Platform Walkthrough (10 min). Organizers will walk participants through the SCARline platform, covering both the physical setup, including the simulator rig, secondary devices acting as in-cabin displays, and the sensor layer, and the software at a conceptual level. A live demonstration will illustrate the researcher's journey through the platform, from launching the system to observing a running study, giving participants a concrete reference point for the hands-on sessions that follow.

Session 3: Widget Creation (80 min). Participants work in small groups using their own laptops to design and implement an HMI widget. To keep the session focused, organizers will present a small selection of widget types to choose from, based on prior experience showing that an open-ended brief generates unnecessary overhead. Participants remain free to decide how their chosen widget should look and behave. Both direct code generation using AI-assisted tools and visual design through Figma are supported. Organizers circulate between groups to answer questions, and completed widget code is handed to the responsible organizer at each station for deployment into SCARline.

Coffee Break (30 min).

Session 4: Study Setup and Live Deployment (50 min). Participants are split into groups, each working at a dedicated SCARline station with one organizer. Organizers demonstrate how the widget created in the previous session is implemented within the platform. Groups then configure a basic but fully functional user study scenario around their widget, defining study conditions, determining what data should be recorded, and observing a short simulated drive with the widget running live. This session gives participants direct experience of the complete SCARline research pipeline, from interface design to study deployment and data collection.

Session 5: Discussion and Feedback (10 min). The workshop closes with a structured discussion on the broader question of accessible and open HMI research tooling, inviting participants to reflect on their experience and share what current platforms still leave unaddressed. A short questionnaire captures their feedback, which will directly inform the continued development of SCARline and provide the basis for a future tutorial publication.

This workshop is open to researchers, designers, and practitioners working in the field of automotive user interfaces and interactive vehicular applications. It is particularly relevant for those interested in simulator-based HMI research, rapid prototyping of in-cabin experiences, and accessible research tooling. No prior knowledge of driving simulators or simulator software is required. Participants are expected to bring their own laptop capable of running an AI-assisted coding tool or Figma for the widget creation session. With the current a half-day workshop plan we are counting on approximately 24 participants (excluding the organizers).

The workshop follows a mixed format combining short presentations with hands-on group activities. The opening sessions are delivered as brief plenary presentations with live demonstration. The hands-on sessions are organized around four dedicated SCARline stations, each supervised by one organizer, allowing participants to work in small groups with direct support throughout. The closing discussion is facilitated as an open group conversation, structured around key questions prepared by the organizers. This format is designed to maximize hands-on time while ensuring participants have sufficient conceptual grounding to engage meaningfully with the platform.

By the end of the workshop, participants will have first-hand experience of the SCARline research pipeline, including HMI widget design and study configuration and deployment. In addition, they will have a concrete mental model of how an abstraction layer over a driving simulator can lower technical barriers to Automotive UX research.

For the organizers and the broader community, the workshop is expected to produce three tangible outcomes. First, the widgets and study scenarios created will serve as a small, diverse corpus of worked examples that stress-test SCARline against research interests beyond those of its original developers. Second, the structured feedback gathered in the closing session, both through open discussion and a short questionnaire, will surface usability issues, missing capabilities, and unmet researcher needs, directly informing continued development of our open-source tool. Third, the discussion is intended to advance a shared community understanding of what accessible and open HMI research tooling should provide, current gaps, and how the field might move toward greater standardization and reproducibility. Insights and materials produced will form the basis for future publications and open research contributions for the AutomotiveUI community.

Monika Szuban is a Master's student in User Experience Design at the Technische Hochschule Ingolstadt. Her research interests lie in gamification and user engagement, exploring how playful design approaches can shape automotive and in-vehicle experiences. Her current research addresses the accessibility of simulator-based user studies, with the aim of supporting designers and researchers across varying levels of technical expertise.

Laura Radetzky is a Master's student in User Experience Design at the Technische Hochschule Ingolstadt. Her work focuses on accessibility, neurodiversity, and gamification in human-computer interaction, including prior research on inclusive gamified questionnaires for neurodivergent participants and automotive gamification. Currently, she contributes to the development of tools that facilitate driving simulator studies and support user-centered automotive research for students and researchers.

Tuğcan Önbaş is a Master's student in User Experience Design at Technische Hochschule Ingolstadt. His work sits at the intersection of UX research, interaction design and software engineering, with interests in adaptive interfaces, human-centered AI and mobility-related user experiences. Currently, he designs and develops interactive prototypes and research tools for human-centered technology research.

Dr. Debargha (Dave) Dey is Assistant Professor for Industrial Design at Eindhoven University of Technology. His research interests are on the human factors of automated driving and intelligent transportation systems, multimodal interaction, and natural user interfaces.

Dr. Ignacio Alvarez holds the Bavarian Top Professorship for Human-Centered Intelligent Systems at Technische Hochschule Ingolstadt. His research interests are at the intersection of agentic AI, systems engineering and human-computer interaction.

Dr. Wendy Ju is Professor of Information Science and Design Tech at Cornell Tech University. Her research interests are primarily focused on the design of interactive systems, particularly human-robot interaction and autonomous car interfaces. She received her Ph.D. in mechanical engineering from Stanford University and her master's degree in media arts and sciences from the Massachusetts Institute of Technology.