The engagement had a fixed duration of six weeks from research initiation to design handoff. The work was organised in coordinated tracks so that research findings, benchmarking and interaction design could inform each other without delay. Weeks one and two were dedicated to remote research with technicians in Germany, while initial mapping of interaction options and embedded GUI constraints started in parallel. During weeks two to four the team refined the interaction design for all three device types and evaluated early concepts against hardware and workshop constraints. Weeks four and five focused on high fidelity prototypes that allowed us to test the logic and timing of the interface. In week six we finalised the visual design and prepared the design system and specifications for engineering.

Benchmarking of competitor systems began early in the project so that we could position the work within the broader landscape of calibration software and technical software UX for automotive tools. In parallel we prepared a developer facing design system that captured interaction rules, component states and behaviour across the OEM display, rugged-tablet and large display. The short delivery time was possible because decisions were grounded in evidence rather than preference. Research, benchmarking and interaction design progressed together, and high fidelity prototypes were used as a shared reference point for both product stakeholders and embedded engineers.

User research was conducted remotely with technicians in Germany because on site visits were not feasible during the pandemic. We spoke with fourteen technicians across five workshops that included authorised inspection centres and independent garages. The research combined contextual interviews and semi-structured interviews. Contextual interviews focused on actual usage and procedure walkthroughs, while semi-structured interviews explored wider issues such as training, error handling and time pressure.

Technicians described calibration steps as if instructing a beginner, which exposed the moments where the old interface created hesitation. The main pain points were linked to speed, clarity and training effort. Technicians often needed to confirm values while walking around a vehicle, yet the old interface did not provide a clear hierarchy and important states did not stand out from secondary information. Several components did not communicate their function visually, which forced workshops to rely on verbal explanations or printed manuals. Under time pressure these limitations contributed to repeated measurements, unnecessary pauses and avoidable uncertainty. These findings became the empirical basis for subsequent interaction design decisions.

To establish a robust interaction architecture, we analysed each module of the system in relation to technician behaviour. The calibration workflow is not a single action. It consists of several phases of measurement, alignment verification and readiness checks that differ slightly depending on the procedure. We examined how users alternate between the embedded OEM display and the rugged-tablet as they move around the vehicle. The small embedded GUI is often checked while standing near the equipment, while the tablet is used when performing adjustments at different positions around the car. The large display in inspection centres must present a coherent view for technicians and inspection staff who are not always close to the hardware.

A table of features was created to capture the behaviour of the system in a structured way. It covered twelve key features grouped into four main modules. For each feature we documented the information required at that step, the precision of the values, the expected technician movement, the effect of lighting and the acceptable time for a user to interpret the display. This analysis became the backbone for the interaction design and for the overall professional software UX. It made it possible to locate bottlenecks that influenced calibration speed and technician safety, and to decide which information had to remain persistent and which could change contextually. In this way the interaction design supported complex workflows without overloading the small embedded interface or the tablet.

Competitor interfaces were reviewed to understand common weaknesses in this category of calibration software and enterprise software UX for technical tools. We examined nine calibration systems from different manufacturers. Many of these interfaces presented densely packed screens with numerous values displayed at the same visual level. Colours were used inconsistently and often mixed status indication with decorative elements. Some systems relied heavily on icons whose meanings were not apparent without prior training.

This benchmarking confirmed that the opportunity was not to introduce more visual variety but to apply structural discipline. A calibration tool must offer stable reading areas, clear grouping of related values and a visual logic that reflects the precision of the underlying hardware. The benchmarking phase helped us define constraints for the new architecture. It clarified which approaches increased cognitive noise and which patterns could be reinterpreted in a more rigorous way for this particular embedded interface and its associated devices.

The previous interface was minimalist and had been designed by engineers to reduce operational risk. Certain workflows functioned well because technicians had learned them over time, and these sequences had to be preserved through constraint respecting. However the interface lacked clear visual hierarchy. Measurement states, tolerances and progress indicators were not emphasised according to their importance. Text and numbers were presented with similar weight, which made it harder for technicians to distinguish between critical and supporting information during calibration.

We treated the old GUI as a constraint rather than an obstacle. The underlying sequences that technicians relied on under pressure were preserved, while the redesign focused on making structure visible and relationships legible. Components that previously required explanation were reshaped so that their role could be inferred from their position, labelling and visual treatment. This approach reduced the transition cost for technicians and avoided the risk of breaking established procedures that already worked in real conditions.

The new interface architecture establishes a clear spatial hierarchy across all devices. Critical values occupy stable zones that remain readable from typical working distances around the vehicle. Procedure states are expressed with consistent visual language on the embedded OEM display, the rugged-tablet and the large display. The presentation of tolerances, warnings and readiness steps follows a single logic, so technicians do not have to adjust their mental model when they move between devices during a calibration sequence. The embedded interface and the larger UIs form one coherent system rather than three unrelated screens.

Interaction design decisions were grounded in the research evidence and in the constraints of the hardware. Three prototype variants were created through option space mapping to explore different ways of grouping values and states on the OEM display, and high fidelity prototypes were then tested in conditions that reproduced workshop lighting and viewing distances. The design system describes component states, transitions and error conditions in detail, including edge situations that are critical in embedded development. Behaviour is specified for all three device classes so that embedded engineers can implement the interface without ambiguity. The result is a technical interface design and embedded GUI architecture that supports fast calibration workflows today and can accommodate additional procedures tomorrow without disrupting existing patterns.