Pandoras Box Mantaris ROV

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Pandoras Box Mantaris ROV

• Dan Kachmarik, John Huberty, Tad Luckey, Erich
  Chen, Jennifer Kerwin

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Overview

• What is an ROV?
• Previous Design Teams
• Project Scope
• Suction Sampler
• Robotic Arm
• Surface Control
• Power Regulation
• Toroid Vessel
• Syntactic Foam
• Management

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What is an ROV?
PC
Low Voltage Enclosure
Joystick
Pilot Box
TV
Phantom Controller
Triton
Transformer
Outlet
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Mantaris
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Major Design Criteria

• Descend to 500 Meters
• Withstand Environmental Conditions
• Preserve Positive Buoyancy
• Enclose Electronics
• Protect Environment
• Use Existing Frame
• Versatile

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Suction SamplerOverview

• Carousel Motor
• Positioning
• Hall Effect Sensor
• Magnets
• Sampling Hose
• Sampling Pump
• Surface Control

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Carousel Motor

• Given
• Max Payload 10 lbs.
• 24 volts _at_ 5 amps
• Oil Filled Housing
• Control from Microcontroller
• Tests to Determine
• Torque 20 to 300 oz-in
• Speed 15 rpm

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Theoretical Motor Analysis

• Calculations
• TMTF TL / (N h)
• I TL/(KT N h) INL
• w VS - (I Rmt) / (KE N)

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Real Life

• Other Considerations
• Cost/Minimum Buying Order
• Lead Times
• Mistakes and Miscommunication
• Motor Driver Ordered
• Motor Pressure Vessel Designed
• Original Motor Order Cancelled
• Maxon Motor

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Position Sensing

• Hall Effect Sensor
• What is a Hall Effect Sensor?
• Mechanical Mounting/Potting
• Problems We Faced

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Speed Control

• 15 rpm Desired
• Motor Controller Outputs Torque/Current Limiting
• Hall Sensors in Motor can be used to Sense Speed
• Microcontroller Takes Input and Raises or Lowers
  Torque to Achieve Speed

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Carousel Control

• Receives Desired Carousel Number
• Rotation logic done on Stamp
• Hall Effect Sensors
• 1 positioning
• 2 rotation speed control
• PWM Output
• Rotation Speed Control
• Hall input to check speed of rotation
• Preset valid speed range of rotation

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Rotation Speed Control Code

• sendpwm
• PULSIN 2, 1, Hall
• IF NOT (Hall gt 4000) (Duty lt 255) THEN next1
• Duty Duty 1
• next1
• IF NOT (Hall lt 3500) (Duty gt 10) THEN next2
• Duty Duty - 1
• next2
• PWM 5, Duty, 10
• RETURN

Hall sensor data
Comparison on microcontroller
Motor
Appropriate PWM value
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Sampling Pump

• Provides Suction for Capture of Sample
• Receives Power Percentage
• Needs an Analog Output to Drive Sampling Pump
• Digital-to-Analog Converter (DAC)
• Digital Potentiometer DS1267
• Stores Values
• Receives Change in -Power

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Gripper Arm

• Built by ExETER IV
• One Degree of Freedom
• 7 lbs. of Lifting Capacity
• Brushed Motor
• We Added
• Driver Circuitry (H-Bridge)
• Microcontroller Control (PWM)

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Power System

• Given 24 Volts at 5 amps
• Two Motors with High Current Draw
• Switching Regulator to Convert to 5 Volts
• Logic/Microcontroller Require 5 Volts
• Brushed Motor Requires 12 Volts

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Whips

• What is a Whip?
• Why we Need Whips
• Toolsled Whip Design

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Surface Control

• Graphical User Interface
• Java Language Used
• Display libraries .awt, .awt.event,
  .javax.swing
• Data Transfer Libraries .io .net
• Direct Telnet Connection to Microcontroller
  Sub-Sea
• Limited Space on Data line from Surface to Sub-Sea

commands
Down the tether
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Sub-Sea Control

• BASIC Stamp 2SX
• Ubicom Microcontroller
• Loops to receive commands
• Connected to the telemetry microcontroller
• Controls
• Carousel Motor
• Gripper Arm Motor
• Sampling Pump

From the surface
Directed to
Telemetry Microcontroller
Our Microcontroller
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Toroid Vessel

• Designed to House Power Conversion System
• Oil Filled Design to Limit Pressure Difference to
  3-7 psi
• Design Considerations
• Geometry
• Location
• Size
• Weight
• Electromagnetic
• Interference

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Toroid VesselWall Thickness Calculations

• Analysis for 0.25 wall thickness
• Calculated Max stress 11,802 psi
• Max allowable stress 40,000 psi
• Safety factor of 3
• Finite Element Analysis on Pro Mechanica verified
  Results

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Toroid VesselOil Reservoir

• Oil is Nearly Incompressible
• Compresses Slightly with Depth but Expands with
  Increase in Temperature
• Oil Bladder System Constructed to allow for
  Expansion and Contraction of Oil
• Bellofram Diaphragm used to Maintain Constant
  Volume of Oil in Toroid Vessel
• Oil Reservoir Attaches to Toroid Vessel by means
  of a Small Tube

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Toroid VesselOil Reservoir

• Constraints
• Rectangular Geometry
• 400 Watts of Heat Produced by Toroids
• Properties of Oil and Seawater
• Approximate 2.25 Gallons of Oil
• Calculated
• Max Temperature of Surface of Toroids
• 392 F (119 C)
• Theoretical Min Temperature
• 36.5 F (2 C)
• Used Bulk Modulus of a Biodegradable Oil to
  Calculate Change in Volume
• ?V ßVo(Tfill-Tmax)
• Oil compensator sized to house ¼ Gallon

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Mass Properties Analysis

• Centers of Mass and Buoyancy Calculated
• Determines Optimal Location for Buoyancy Material
• Piloting Stability was Maximized by Placement of
  Syntactic Foam

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Syntactic Foam

• 2 Modules Manufactured to Maintain Versatility
• Tool Sled Module
• Vehicle Module
• Size of Foam Determined through Buoyancy
  Calculations
• Buoyancy V(Density of foam Density of Sea
  H20)
• Sized to allow for Future Scientific Equipment

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Project Management

• Interdisciplinary Team
• Different Schedules and Meeting Times
• Required Class outside of Senior Design Marine
  Operations
• Economics
• Sampling Pump 6,000
• Syntactic Foam 2,675
• Total 10,062

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Conclusion

• Completed
• Suction Sampler
• Robotic Arm
• Power Regulation
• Surface and Subsea Control Established
• Toroid Vessel Housing and Oil Reservoir
• 2 Additional Modules of Syntactic Foam
• Added Two Scientific Instruments Beyond Basic
  Platform
• Ready for Successful Deployment in Late Summer

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Special Thanks

• Geoff Wheat NOAA Undersea Research Program and
  University of Alaska, Fairbanks
• Bill Kirkwood and Farley Shane MBARI
• Chris Kitts, Neil Quinn, Tim Hight, Pascal Stang,
  Don McCubin and Tibor Hites SCU
• Ned Biglieri SCU Alumni Board
• Oli Francis and Graeme Coakley - Idean Robotics
• Paul Mahacek and Jack Mccabe Junior Interns
• Cherry Electrical Products

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Questions?
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Stability Analysis

• The righting moment produced by the additional
  foam was calculated to determine horizontal
  offset under operation
• Horizontal offset of 5 degrees