Tortuga II Hardware
The vehicle's hardware holds all of its part together and protects them from the underwater environment. As you can see in the figure 1 below, the main components of the vehicle's hardware are the landing gear, frame, thrusters, camera housing, and pressure hull.
Figure 1. An overall view of the vehicle showings it main hardware parts.
Skids
Skids provide support for the vehicle when its sitting on dry land and protection from obstacles when in the water. The skids are composed of a series of tubes mounted to the vehicle with nylon rods. The front and rear portion of the skids are rounded to reduce the possibility of snagging an underwater obstacle if the vehicle navigates to close to them. The nylon rods, which mount the skids to the frame, absorb some of the shock from any impacts the vehicle might endure. The skids are sized to enclose all of other parts on the vehicle. This enclosure allows the skids to support the vehicle when outside of the water, and protect it while underwater.
Frame
The frame is the vehicle's main structural component and it rigidly holds all parts of the vehicle together. It is about thirty two inches long and nine inches square. Its constructed primarily of 80/20, a type of slotted extruded aluminum rod. The slots on the aluminum rods allow other components to be attached and moved around for different mission configurations. The frame is designed to provide protection to the vehicle's camera housing and pressure hull. The rear section of the frame, along with the rear thruster, detaches to allow the pressure hull to be inserted inside the rest of the frame.
Thrusters
Thrusters provide the force to move the vehicle through the water. The vehicle has six Seabotix BTD150 thrusters mounted on the outside of the frame in three pairs. Each pair of thrusters move the vehicle along one axis, and spin it along another. Together all the thrusters allow the vehicle to move in all six directions: forward and backward, side to side, up and down, yaw, pitch and roll (Figure 2).
Figure 2. A view from the top, front and left side of the vehicle showing the thrusters directions.
Camera Housing
The camera housing is a clear polycarbonate box made from an off the shelf Ikelite underwater enclosure. Inside it are two firewire cameras and internal plastic supports. On its rear face is an eight pin Subconn connector. It provides a dry and clear compartment for the vehicle's forward and downward camera. It is connected to the pressure hull by a cable connected to the connector on the rear of the housing (Figure 3)..
Figure 3. A close up of camera housing showing its internal parts.
Pressure Hull
The pressure hull provides a dry compartment for the vehicle's electronics and main computer. It is composed of a ΒΌ inch thick, eighteen inch long, acrylic cylinder capped with a pair of aluminum end caps (Figure 4). The cylinder has an outer diameter of eight inches and is clear to allow inspection of components inside it. Both the front and read end caps seal against the acrylic tube with a piston seal. A piston seal is mechanical system which prevents water from entering the pressure hull by placing a rubber ring between part of the end cap inside the acrylic tube and the tube's wall. Both the front and read end caps have a number of Subconn wet-mate connectors (cables that you can plug and unplug underwater) to allow connection to thrusters, and sensors outside of the pressure hull.
Figure 4. Pressure hull.
Electronics Rack
The electronics rack is the support structure for all the electrical components inside the pressure hull. It is made of set a angled aluminum rails with mating plates at either end. The electronics rack keeps all of the vehicle's main electrical components together and allows for there removal from the vehicle without having to disconnect individual wires. The connector plates mate to both the front and rear end caps of the pressure hull. The connectors on the mating plate connect the electronics on the rack to the wet-mate connectors on the end caps. It is through these connections that the electronics are able communicate with the components on the outside of the pressure hull.
Figure 5. Inside view of the pressure hull showing electronics rack.
