General Use Cases

The DVL can be deployed in several different use cases.

One use case is to measure displacement of the DVL (and by extension, the ROV to which it is attached) in real-world coordinates. This activity integrates (generally) horizontal motions in conjunction with an Inertial Measurement Unit (IMU). With a known starting position in world coordinates (e.g., latitude and longitude), the DVL can estimate its present position in lat/long after moving around. A good-quality IMU is needed for this, as is described later in this manual.

Another case is to measure displacement of the DVL and ROV in a coordinate frame relative to the ROV. This is used, for example, to hold the DVL at a fixed position relative to a target surface. The DVL will output delta position and orientation in the ROV frame. This capability does not require nearly as good an IMU as is needed for real-world dead reckoning. If the position deltas are mathematically integrated (by the user) they can provide a position estimate in ROV coordinates as the ROV moves along the target surface.

DVLs are sometimes deployed as an Acoustic Doppler Current Profiler (ADCP). This is used to measure water current velocities over a depth range using the Doppler effect of sound waves scattered back from particles within the water column. The Cerulean Sonar DVL-75 is not suited to this usage.