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Case study 001 · HMI · Human-AI interaction

GIVE THE VEHICLE A MIND

A context-aware in-car AI HMI that detects when delay breaks a real commitment and offers the next best action without pulling the driver into a phone workflow.

Outcome State-driven React HMI prototype
Evaluation 5 interviews → 5 same-participant usability tests
Core idea AI as embedded vehicle behaviour
93%
Helpfulness across 3 core delay scenarios · 14/15 positive
100%
Said it would reduce phone reliance while driving
100%
Trusted the system when actions stayed confirmation-based
02 -
Final experience

INTERACTIVE DEMO / FINAL EXPERIENCE

The quickest way to understand the concept is to watch the journey change meaning. The interface starts as a normal drive, detects that delay now threatens a commitment, offers bounded support, then returns to the driving state after confirmation.

JSON scenario data JavaScript scenario engine React components Live walkthrough

Scenario set

Scenario What the car detects Actions offered
Late for Meeting ETA exceeds meeting start time. Call · Message · Reschedule
Late for Reservation ETA exceeds booking time, restaurant context. Call restaurant · Request reschedule
Running Home Late ETA exceeds expected home time, partner context. Text "5 min late" · Share location · Call
Tired Inferred driver state. Rest stops · Upbeat music
Too Warm Inferred cabin discomfort. Lower AC · Open window · Open panorama
Three core delay scenarios plus two exploratory vehicle-state scenarios.
Nothing sensitive happens silently. The car prepares the message, offers the remote join, and drafts the location share — the driver confirms with one tap or voice. — Bounded autonomy line
03 -
Insight

THE INSIGHT / WHY THIS MATTERS

Delay is not experienced as a traffic problem. It becomes a coordination problem the moment ETA collides with a meeting, reservation, or person waiting at home.

Most in-car AI assistants still behave reactively: the driver asks, the system answers. That misses the high-stress moment when the driver is already managing time pressure and is most likely to reach for a phone.

That fallback sits inside a real safety problem. NHTSA reports 3,275 deaths in crashes involving distracted drivers in 2023.

Interview evidence · n=5

Trapped in the car.
P1·Delay as loss of control
Called a coworker to stall for time before a meeting.
P2·Phone fallback
My brain is packed up.
P3·Need for support
There is no proactivity by the system itself.
P4·Assistant gap
Not very useful.
P5·Current systems
How might an in-car AI system use contextual awareness to support drivers during delay-related, time-critical journeys without increasing distraction or breaking mental flow? — Problem statement

The concept response was deliberately narrow: not another assistant, and not a chat layer. A vehicle should notice when a routine journey has become consequential and surface the single next best action in the existing HMI.

Core proposition: AI as embedded vehicle behaviour, not as an added tool.

04 -
Process

PROCESS & RESEARCH

Secondary research set the safety constraints: short-glance design, limited eyes-off-road time, and human-AI interaction principles from Amershi, Shneiderman, and Norman. Primary research made the product logic sharper: delay only matters when it breaks a commitment.

I used the research to make interaction decisions rather than to document a chronological design process.

01

Insight

Drivers described delay as coordination stress, not route frustration.

Decision: Trigger support only when ETA intersects with a real commitment.

02

Interaction

The phone was the default workaround, even when participants knew it was unsafe.

Decision: Put the next action inside the existing HMI instead of asking drivers to switch tools.

03

Trust boundary

Proactive support was wanted only when it stayed bounded.

Decision: The car drafts, prepares, and suggests. The driver confirms every sensitive action.

04

Presentation

Distraction risk made visual hierarchy more important than feature density.

Decision: Use a compact top banner, route colour shift, and calendar conflict badge instead of a conversational surface.

Artefacts produced
  • 012 proto-personas: time-pressured business professional and socially-driven younger user.
  • 02User journey map mood-coded across 6 stages from before trip to after support.
  • 03Mental model sketch: current manual delay management vs. proposed next-best-action support.
  • 04Information architecture: Input → Interpretation → Output with progressive disclosure.
05 -
Evidence

VALIDATION / EVIDENCE

I ran follow-up sessions with the same 5 participants and tested the concept against four hypotheses. Percentages are positive responses out of 15: 5 participants across 3 core delay scenarios.

H1 — Hypothesis 1Supported

Proactive support is more helpful than passive systems

0%14 / 15

Reservation scenario hit hardest. Meeting and Late Home consistently positive.

H2 — Hypothesis 2Supported

Embedded support reduces phone reliance

0%15 / 15

Strongest result. Directly addresses the workaround behaviour found in interviews.

H3 — Hypothesis 3Conditional

Confirmation-based action increases trust

0%15 / 15

Trust held as long as the system stayed suggestion-based. The moment automation overreached, trust collapsed.

H4 — Hypothesis 4Directional

Reduced information load lowers distraction

0%12 / 15

Directionally supported. Wording, hierarchy, and option count still need refinement.

Hypothesis results from 5 participants × 3 core delay scenarios.

Where participants drew the line

Signal Boundary
Wanted Drafting a message.
Wanted Suggesting "join remotely".
Wanted Surfacing the restaurant's number.
Rejected Sending anything without confirmation, every participant.
Rejected Auto-joining a meeting.
Rejected Decisions about scheduling without sign-off.
Softer reception Tired and Too Warm scenarios: not annoying, but not as obviously useful.

Participants did not reject proactivity. They rejected irrelevant or overreaching proactivity. The same prompt at the wrong moment would have failed; in the core delay scenarios, the system appeared only after delay had clearly broken a commitment.

Evaluation artefacts and backlog
  • 01Stronger confirmation feedback after an action: sent or shared state.
  • 02Tighter visual hierarchy on the action card with a clearer primary action.
  • 03Reduce option count in some scenarios.
  • 04Add Share Location as a first-class option in Late Home.
  • 05Justify the value of exploratory scenarios more clearly, or drop them.
06 -
System

TECHNICAL / SYSTEM THINKING

The challenge was not generating AI responses. It was deciding when context was meaningful enough to interrupt the HMI at all, and then keeping the intervention bounded.

Technology logic and blueprint

The system fuses signals that are not new in isolation, but meaningful together: route and live ETA, calendar timing, traffic, communication context, vehicle state, trip context, and learned behaviour patterns.

01

Delay detection

Has the ETA shifted meaningfully versus the planned arrival?

02

Commitment matching

Is there a calendar event, reservation, or known obligation tied to this trip?

03

Relevance assessment

Does the new ETA now break that commitment?

04

Situation classification

Work, social, family, or general context changes tone and action set.

A delay only triggers intervention when all checks line up. A slow drive with nothing scheduled stays silent. The same slow drive 20 minutes before a meeting surfaces support.

07 -
Reflection

REFLECTION / NEXT STEPS

  • 01The value lives at the intersection of route, ETA, and commitment.Without all three, the system has nothing meaningful to say.
  • 02Trust does not equal automation.Trust came from the system holding back, not from doing more.
  • 03Concept logic mattered more than the final pixels.The idea validated more cleanly than the presentation layer; distraction-related refinement is the next iteration.
  • 04The evidence is still qualitative.Small sample, self-reported measures, and no glance-tracking or simulator-based workload testing.

Next step

Keep the next version focused on the three validated core scenarios: Late for Meeting, Late for Reservation, and Running Home Late. Refine hierarchy, confirmation feedback, and option count before claiming low-distraction performance.

After a larger sample and simulator testing with objective workload measures such as NASA-TLX and eyes-off-road time, the same framework can extend into adjacent areas such as fatigue and trip-mode personalisation.

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Moritz Wallbrecher