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A.U.V.

A.U.V. Emeric Rochford Dale Williams Bryan Douse Ryan Gray. Background. Autonomous underwater vehicles are becoming popular in many applications, including oil exploration, and marine studies.

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A.U.V.

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  1. A.U.V. Emeric Rochford Dale Williams Bryan Douse Ryan Gray

  2. Background Autonomous underwater vehicles are becoming popular in many applications, including oil exploration, and marine studies. Underwater vehicles are also used to check the hulls of large ships for homeland security, and maintenance. Ryan

  3. Mission Statement • Original design specifications were derived from an AUV competition in San Diego, California. • Design an Autonomous Underwater Vehicle that can operate at depths up to 38 feet. • The Vehicle must descend to a predetermined depth and remain at this depth during its mission. • While underwater the AUV must remain stable on both vertical and horizontal planes. Ryan

  4. Solution • Hull constructed from PVC tubing • Four electric motor driven propellers for propulsion and steering • Linear leveling system for stability control • Water pressure used for depth sensing • Use HC08 microcontrollers for subsystem control Ryan

  5. Internal System Overview Side View Emeric

  6. External System Overview Emeric

  7. Hull Emeric

  8. Hull Testing Hull Testing • Torque = 20 ft lbs • Depth = 3.5 ft • Time Submerged = 15 min No Leaks! Emeric

  9. Propulsion Motor Assembly • Minimum Requirements: • Torque 1.012 ft lbs • Power 0.114 hp • Thrust 1.3 lbs • Motor Selected: • CerMag RS 540S • 12 Volts • Thrust x2 with a 3” prop • = 3.1lbs Total Hydrodynamic Drag Force of Hull = 84.9 N or 19.08 lbf Emeric

  10. Depth Sensing • There is a linear relationship between pressure and depth. • The following is the mathematical representation of the relationship: • ΔP = γh • ΔP  Pressure Difference • γ  Specific Weight of Liquid Bryan

  11. Freescale MPX4250AP Ported Pressure Sensor Bryan

  12. Pressure Sensor Tests • The data collected from the pool test shows that the sensor has a linear output of about 62mV per foot. • This gives us a full scale voltage of about 4.25 V which provides an excellent resolution to feed into the A2D converter on the HC08. Bryan

  13. Leveling System Design The leveling system operates by redistributing weight in the hull of the vehicle. The mechanical design consist of a motor coupled to a lead screw with a weigh threaded onto it. The motor can be commanded to turn clockwise or counter clockwise to move the mass up and down the hull as needed. This is the only leveling system that is needed because the hull is designed in a way that most of the weight is at the bottom of the vehicle to stabilize it in the other direction. Dale

  14. Leveling System Control Circuit The electrical design consists of a potentiometer with a pendulum on it to sense the angle of tilt the AUV is at. This signal is than input into two comparators to determine if the weight should be moved, and if so what direction. Dale

  15. Electrical Overview `` Sensors Sensors 9 volt battery HC08 HC08 Control Circuit Opto- Isolator Opto- Isolator Opto- Isolator Opto- Isolator Motor Controller Motor Controller Motor Controller Motor Controller Leveling Motor 12 volt battery Depth Control Subsystem Propulsion Subsystem Leveling Subsystem Ryan

  16. Depth Control System Water Sensor HC08 Pressure Sensor Opto- Isolator Depth Motor Driver Motor Ryan Ryan

  17. Software Overview Depth Control Start // initialize variables CMD = 200; //Value we set for our depth A2D = 0; PWM = 0; COUNT = 0; ConfigurePorts(); ConfigureTimebase(); ConfigureSCI(); ConfigureIRQ(); StartA2D(); Void Controller (void) { Call controller = 0; //summing junction Xn = CMD – A2D; //controller Yn = 255 * Xn; //check and limit saturation If ( Yn > 255.0 ) { Yn = 255.0; } Else if ( Yn < - 255.0 ) { Yn = - 255.0; } // load Pulse Width Modulator if ( Yn < 0 ) { Yn =0; } PWM = ( char ) Yn LoadPWM (); startA2D(); return; Water Present in hull? Yes No Surface Yes depth equal to 30? No depth Greater than 30? No Yes Ascend descend Ryan

  18. Sonar Overview • For the design competition our AUV is required to follow a sonar ping. • The sonar receiver operates by containing an array of three sonar sensors spaced 60 degrees apart. Each of the detectors will output independent signals into a microcontroller that will than decide what direction to steer the vehicle to point it towards the sonar transmitter. Dale

  19. Budget Dale

  20. Schedule Bryan

  21. Summary • Currently our hull design is complete and we have assembled a sealed prototype. • Our depth control system is operational as well as our leveling system. • What remains to be accomplished is the completion and installation of our navigation system. Questions? Bryan

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