Underwater Navigation
To navigate underwater, there are a couple of solutions that are widely used. Almost every one of these solutions uses a camera that will essentially see underwater.
Inertial Measurement Unit (IMU)
The inertial measurement unit is a sensor chip that contains a 3-axis gyroscope, 3-axis accelerometer, and a compass. It is located in the pixhawk software and many modern-day smartphones and VR headsets. We will be most likely using this style because one of our requirements, as discussed in a future section, requires the use of pixhawk. This will take into effect our initial position and track our movement over time to see where it is at.
Depth Sensor
In future equations, the depth is given as a value from zero to ten meters. At each depth is a specific pressure, and by rearranging the equation we can use a depth sensor to calculate the depth at a given pressure. It is a simple device that would stick out the side of the UUV in a watertight seal. This would give many advantages such as autonomous depth control and increase navigational accuracy. It would also allow for a smoother sailing experience and less shake your camera under the water, wow fighting off currents.
Ultra Short Baseline (USBL)
This type of navigation requires sending a beacon to triangulate three points and can be a very accurate way of navigation. The math for this is also very simple and almost elementary, so it will not be discussed here. We thought about using this type of navigation but the pinging hardware alone costs above quadruple our budget so it would not be worth it.
Doppler Velocity Log (DVL)
The Doppler velocity log is simply a type of sonar that tracks the ground velocity and location, almost like the short baseline positioning system except pointing the trackers at the ground. Again this would be way too costly for our application so it is not necessary but again it is cool to know the information and science behind it.
