Technical Specifications
Complete technical specifications for the Data Walker mobility assessment system.
Measurement Resolution & Accuracy
| Parameter | Metric | Imperial |
|---|---|---|
| Resolution (per pulse) | 131.5 mm | 5.18 inches |
| Theoretical precision | ±65.75 mm | ±2.59 inches |
| Accuracy at 10m | ±131.5mm (~±1.3%) | |
How It Works
The system detects distance in discrete increments of one magnetic pulse. Each pulse represents 131.5mm of travel, providing measurement resolution suitable for clinical gait assessment.
Wheel Configuration
| Parameter | Value |
|---|---|
| Diameter | 125.6mm (4.94") |
| Circumference | 394.5mm (15.53") |
| Magnets | 3 neodymium |
| Magnet spacing | 120° apart |
| Distance per rotation | 1.30 feet (394.5mm) |
Hall Effect Sensor
| Parameter | Value |
|---|---|
| Model | A3144E / A3144 |
| Type | Digital output |
| GPIO Pin | 35 |
| Trigger | RISING edge |
| Debounce | 50ms |
Processing Unit
| Parameter | Value |
|---|---|
| Board | ESP32-2432S028R |
| Processor | ESP32-WROOM-32 (dual-core 240MHz) |
| Display | 2.8" TFT (320×240) |
| Touch | XPT2046 resistive |
| Power | 5V USB-C |
Performance Metrics
| Parameter | Specification | Notes |
|---|---|---|
| Distance accuracy | ±131.5mm (±1 pulse) | ~1.3% at 10m |
| Speed range | 0.2 - 2.5 m/s | Typical walking speeds |
| Speed resolution | 0.01 m/s | Display precision |
| Update rate | 10 Hz display, 1 Hz speed | 100ms / 1000ms |
| Battery life | 8-10 hours | 5000mAh power bank |
| Operating current | 150-200mA | Typical operation |
Clinical Test Capabilities
10-Meter Walk Test
| Test distance | 14m total (2m warmup + 10m measured + 2m cooldown) |
| Measurement precision | ±131.5mm (~±1.3% at 10m) |
| Timing resolution | 0.1 seconds |
| Features | Automatic risk assessment based on gait speed thresholds |
TUG (Timed Up and Go) Test
| Turn detection | 3.0 meters (±131.5mm) |
| Audio cues | Start beep and turn notification |
| Visual prompts | “GO STRAIGHT” → “TURN AROUND” → “GO BACK” |
| Risk categories | Normal (<12s), Fall Risk (12-15s), High Risk (>15s) |
Manual Stopwatch
| Display format | MM:SS.T (up to 99:59.9) |
| Controls | START/STOP, RESET, HOME |
| Visual feedback | Green (running), Yellow (stopped) |
| Auto-protection | Stops when navigating away |
Validation Testing
Post-assembly verification results demonstrate measurement accuracy:
| Test | Expected | Measured | Status |
|---|---|---|---|
| Manual rotation (1 turn) | 1.30 feet | 1.30 feet | Pass |
| 10-foot walk | 10.0 feet | 10.0 ± 0.2 feet | Pass |
| 20-foot walk | 20.0 feet | 20.0 ± 0.3 feet | Pass |