Advanced Technology Underwater Gravity System for Autonomous Underwater Vehicles
Dynamic Gravity Systems has developed the AT1U as a solution for users that that would like to add a dynamic gravity meter for their existing Autonomous Underwater Vehicle (AUV), for underwater marine survey applications. The systems include the gravity sensor, gyroscopically stabilized gimbal platform, and the electronics necessary for acquiring and recording the gravity vertical accelerations, sensor temperature, and other data signals. The AT1U has very high stability and low drift, with an excellent Clamp / Un-clamp repeatability.
Technical Specifications
| Gravity Range | Full World-Wide Range (20,000 mGals) |
| Resolution | 0.01 milliGals (mGals) |
| Temperature Range | -25°C to +45°C |
| Dimension (approx) | 20(l) x 18(w) x 25(h) cm |
| Power Source | Rechargeable Lithium Battery DC Power Integration (24V) |
| Weight (sensor & gimbal) | 16.2 kg 35.7 lbs |
| Sensor Type | Full-feedback zero-length spring with 2 axis gimbal and gyro controlled platform |
| Data Collection | Internal data logger, and serial data output |
| Drift Rate | < 1 mGal/month from factory < 0.5 mGal/month after spring aging |
| Data Recording Frequency | 1Hz |
| Power Consumption (approx) | 40 watts |
| Static Repeatability | 0.01 to 0.02 mGals |
Gravity is a powerful tool to profile underground structures. Surface ship gravity is an efficient way to collect gravity data over a relatively large marine region with medium resolution, due to the distance from the sea floor. Static sea-floor gravity meters can observe gravity with high resolution, but are limited to small areas and quiet sites.
The AT1U can allow operators to match the performance of the sea bottom meters, but over a much larger area through integration with your autonomous underwater vehicle (AUV), allowing high-resolution data collection over an area dependent only on your AUV platform.
Typically, gravity drifts less than 2 mGals/month and 0.5 mGals/month after aging. This sensor also has excellent clamp / un-clamp repeatability, almost comparable with a Land Meter, which allows the meter to be used as a sea bottom surveying meter with repeatability better than 0.030 mGals. The AT1U has been designed as a Dynamic Gravity Sensor with with a world-wide gravity range of 20,000 mGals making the sensor ideal for dynamic gravity reading. For this application the user needs to provide accurate positioning capability. A typical repeatability of the dynamic readings is σ < 0.060 mGal.