See how DVL velocity measurements dramatically reduce position drift from 1-2% to < 0.2% of distance traveled
Doppler Velocity Logs measure vehicle velocity relative to the seafloor using acoustic Doppler shift. By providing accurate velocity measurements, DVL dramatically reduces INS drift. This demo compares INS-only navigation against DVL-aided navigation to show the improvement. DVL accuracy degrades with altitude above the seafloor - adjust parameters to see the effects.
| Altitude Range | SNR (dB) | Velocity Accuracy | Bottom Lock | Typical Use Case |
|---|---|---|---|---|
| 5-50 m | 35-45 dB | ±0.005 m/s | Excellent | Near-bottom surveys, inspection |
| 50-100 m | 25-35 dB | ±0.010 m/s | Good | Standard navigation, mapping |
| 100-150 m | 15-25 dB | ±0.020 m/s | Marginal | High-altitude transit |
| 150-200 m | 10-15 dB | ±0.050 m/s | Poor | Edge of operating envelope |
| > 200 m | < 10 dB | N/A | Lock Lost | No bottom tracking available |
DVL measures velocity by transmitting acoustic pulses and measuring the Doppler shift in the reflected signal:
Where:
DVLs use 4 beams in a Janus configuration (opposing pairs) to measure 3D velocity and provide redundancy. This configuration cancels out errors due to vehicle pitch and roll.
DVL measurements update the velocity states in the navigation filter:
The measurement innovation is the difference between INS-computed velocity and DVL-measured velocity, allowing the Kalman filter to correct velocity errors before they integrate into large position errors.