Method Specification · Naturalistic Driving Observation

Driver Fatigue
Capture Protocol

DOC / FTG-CAP.01
REV / 2026.04
OPPOSITE × ROAD UX
A rotating, multi-angle iPhone camera method for observing the early indicators of driver fatigue — combining driver-facing, cabin, road and inertial data across a multi-day capture window.

Principle

No single camera position captures fatigue. The driver, the vehicle and the environment are each partial sensors. Rotating mount positions across days surfaces signals that remain hidden in any one fixed view.

Device

iPhone 14+ with 60fps video, accelerometer and gyroscope streams. Mounted on suction arm or dash cradle, rotated per schedule. Supplementary audio capture throughout.

01 ▸

Camera Position Schematic

WINDSCREEN REAR WINDOW DASHBOARD DRIVER PASSENGER DRIVER SIDE PASSENGER SIDE ↑ DIRECTION OF TRAVEL 1 P1 · FRONTAL 2 P2 · SIDE PROFILE passenger window 3 P3 · ROAD VIEW 4 P4 · OVER-SHOULDER rear-right cabin 5 P5 · CABIN WIDE ≈ 1m LEGEND camera mount line of sight
02 ▸

Rotation Schedule — 7-Day Window

Protocol Each driver completes a 7-day capture window. Camera position is rotated daily across two time-of-day slots (AM / PM) to de-confound fatigue signal from position effects.

Inertial + audio streams run continuously regardless of camera position.
SLOT
Mon
Tue
Wed
Thu
Fri
Sat
Sun
AM
P1
P2
P3
P4
P5
P1
P2
PM
P3
P4
P5
P1
P2
P3
P4
03 ▸

Parallel Data Streams

STREAM A

Visual

Driver-facing or road-facing video at 60fps, 1080p minimum. Rotated per schedule.

BLINK RATE · HEAD POSE · POSTURE
STREAM B

Inertial

Accelerometer and gyroscope from mounted iPhone — picks up steering micro-corrections, braking smoothness, road texture.

VIBRATION · JERK · DRIFT
STREAM C

Audio

Continuous audio capture — yawns, sighs, vocal tonality changes, ambient cabin noise and engine load.

YAWN DETECT · PROSODY
STREAM D

Environment

Timestamped GPS + road type log for traffic density, route complexity, glare and monotony context.

ROUTE · LIGHT · LOAD
04 ▸

Participant Protocol

PROTOCOL · PRE-DRIVE

Pre-journey survey

Participants complete a short structured survey before every driver journey, capturing subjective baseline state: sleep duration and quality the previous night, Karolinska Sleepiness Scale rating, caffeine and meal intake in the past two hours, mood, and any medication or illness flags.

BASELINE · SLEEP · KSS
PROTOCOL · POST-DRIVE

Post-journey survey

Participants complete a matching survey immediately after every driver journey: end-state KSS, perceived fatigue and effort, critical incidents or near-misses, route conditions (traffic, weather, glare) and any unplanned stops. Bookending every drive gives us delta between expected and experienced state.

KSS Δ · INCIDENTS · EFFORT
PROTOCOL · WEARABLE

Continuous Fitbit wear

Each participant wears an issued Fitbit 24/7 for the full study period, including sleep, and is responsible for charging it daily (shower or fixed routine slot). Captures continuous heart rate, HRV, sleep stages and consistency, activity and sedentary periods, SpO₂ and skin temperature — the physiological spine beneath the observational data.

HR · HRV · SLEEP · ACTIVITY
PROTOCOL · COMPLIANCE

Participant responsibilities

Drivers are briefed on: wearing the Fitbit at all times and syncing daily; completing both surveys for every journey (no exceptions); charging the device on a fixed daily routine; flagging any missed wear period longer than four hours. Non-compliance is logged, not punished — but compliance is the dataset.

WEAR · CHARGE · SYNC · REPORT