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Final Buoyancy System Design

The resurfacing system was generated out of the requirement that the data would need to be retrieved and that the robot would not be self propelled.  That led the team to come up with a design which would allow for the retrieval of the robot at the surface of the water.  One of the assumptions the team has during this design was that once the robot comes to the end of the cave system the water current has carried the robot up from a depth of 300ft to a depth where sunlight is able to penetrate the cave system.  The design then allows for the robot to resurface the rest of the way. 

The resurfacing system works by generating electricity from sunlight which will light up the cave opening.  Using a photovoltaic cell, the cell is able to convert solar power into electrical power, which is used to operate a solenoid valve.  Similar to the buoyancy system, the resurfacing system operates off of carbon dioxide gas.  As the gas is released into a bladder by the solenoid valve, the robot increases its’ buoyancy by displacing water.  The difference between the two systems is the resurfacing system inflates a bladder permanently while the buoyancy system inflates and deflates a bladder.  Below is a flow chart that demonstrates how the parts used in the resurfacing system are connected.

The resurfacing system is broken down into several components which allow it to operate properly.  The photocell is used to generate electricity from sunlight.  The electricity generated by the photocell is then used to operate the microcontroller.  The microcontroller is used to open and close the solenoid valve.  The solenoid valve allows the carbon dioxide to pass through the valve when it is opened and then prevents it from flowing back after the valve is closed.  The solenoid valve allows the carbon dioxide to inflate a bladder which causes positive buoyancy in the robot.  The robot is then able to rise to the surface until the bladder deflates or the robot is recovered.  During the testing of several components the team found that the photocell can generate electricity in less than ideal conditions but the amount of electricity generated is directly dependent on the amount of sunlight available.