Technical comparison of representative track geometry measurement platforms
| Trolley | Track recording vehicle | In-service vehicle | Smartphone | Drone | |
|---|---|---|---|---|---|
| Measurement principle | Inertial + optical encoder | Inertial + laser profiling | Inertial (car-body/bogie accel.) | MEMS accelerometer + GPS | LiDAR + stereo vision |
| Main sensor type | IMU, laser ranger, encoder | IMU, gyro, laser cameras, GPS | Accelerometers, rate gyro, GPS | 3-axis accel., gyro, GPS | LiDAR, RGB camera, IMU, GPS |
| Sampling resolution | 0.25 m | 0.25 m | 0.5–1 m (dependent on speed) | 10–100 Hz (time-based) | 0.05–0.1 m |
| Operating speed | Manual push (≤5 km/h) | Up to 160 km/h | Revenue speed (≤240 km/h) | Any (passenger ride) | ≤30 km/h (hover/slow) |
| Measurable parameters | Long. level, alignment, gauge, cant, twist | Long. level, alignment, gauge, cant, twist | Vertical/lateral accel., derived geometry | Vibration level, qualitative comfort | Gauge, alignment (2D), defects (visual) |
| Accuracy | ±1 mm, calibration before each use | ±0.5 mm, periodic calibration | Low (qualitative trend), no absolute calibration | High drift, needs frequent recalibration | ±10–30 mm (absolute), needs ground control |
| Spatial wavelength range | 3–50 m (short to medium) | 3–120 m (medium to long) | 10–100 m (medium, speed-dependent) | Limited (aliasing, noise) | 1–20 m (short) |
| Data processing pipeline | Real-time display, offline post-processing | Onboard processing + web reporting | Edge processing (limited real-time) | Cloud post-processing | Offline point cloud processing |
| Trolley | Track recording vehicle | In-service vehicle | Smartphone | Drone | |
|---|---|---|---|---|---|
| Measurement principle | Inertial + optical encoder | Inertial + laser profiling | Inertial (car-body/bogie accel.) | MEMS accelerometer + GPS | LiDAR + stereo vision |
| Main sensor type | IMU, laser ranger, encoder | IMU, gyro, laser cameras, GPS | Accelerometers, rate gyro, GPS | 3-axis accel., gyro, GPS | LiDAR, RGB camera, IMU, GPS |
| Sampling resolution | 0.25 m | 0.25 m | 0.5–1 m (dependent on speed) | 10–100 Hz (time-based) | 0.05–0.1 m |
| Operating speed | Manual push (≤5 km/h) | Up to 160 km/h | Revenue speed (≤240 km/h) | Any (passenger ride) | ≤30 km/h (hover/slow) |
| Measurable parameters | Long. level, alignment, gauge, cant, twist | Long. level, alignment, gauge, cant, twist | Vertical/lateral accel., derived geometry | Vibration level, qualitative comfort | Gauge, alignment (2D), defects (visual) |
| Accuracy | ±1 mm, calibration before each use | ±0.5 mm, periodic calibration | Low (qualitative trend), no absolute calibration | High drift, needs frequent recalibration | ±10–30 mm (absolute), needs ground control |
| Spatial wavelength range | 3–50 m (short to medium) | 3–120 m (medium to long) | 10–100 m (medium, speed-dependent) | Limited (aliasing, noise) | 1–20 m (short) |
| Data processing pipeline | Real-time display, offline post-processing | Onboard processing + web reporting | Edge processing (limited real-time) | Cloud post-processing | Offline point cloud processing |
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