me 442 senior project
DESCRIPTION
ME 442 Senior Project. Autonomous Hovercraft – Class of 2008-2009. Project Summary 4/30/09. Joseph Cochrane, Patrick Dickey, Aldo Glean, James McMahon, Omar Monterrubio, Kalin Petersen, Jason Shao. Post-Conflict Mine Fields. - PowerPoint PPT PresentationTRANSCRIPT
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ME 442 Senior ProjectAutonomous Hovercraft – Class of 2008-2009
Joseph Cochrane, Patrick Dickey, Aldo Glean, James McMahon,
Omar Monterrubio, Kalin Petersen, Jason Shao
Project Summary4/30/09
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Post-Conflict Mine Fields• Unexploded landmines from previous
military conflicts are still a prevalent issue in civilian 3rd world areas
• Estimated 1 million unexploded landmines left over from a skirmish between Israel and Lebanon in 2006
• Cambodia has one amputee for every 290 people - one of the highest ratios in the world.
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Landmines• Anti-personnel landmines are generally small and designed to maim,
not kill• Most anti-personnel landmines are detonated when about 5psi of
contact pressure is applied to a triggering mechanism on the device • Can be triggered via a person stepping on device, driving over device,
increased pressure or vibration
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Why a Hovercraft?• Is a vehicle that uses an engine to drive a large fan
inside a structure, which creates an air cushion within a fabric skirt
• Provides lift force to counteract the weight of the craft while applying very little pressure to the surface beneath, ~0.1psi
• Capable of traveling over solid, marshy and wet terrains, making it adaptable to the various rural environments
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Our Concept
• We intend to develop a means for civilian land-mine location that is inexpensive and easily reparable
• Our intention is to design the platform for carrying detection technology, not develop the technology itself
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• ME 441 summary • Ground Penetrating Radar (GPR)• Lift engine mount • Lift engine shroud • Pressure testing • Pulley attachment • Propulsion and electronics power systems • Thruster housing mesh and design testing • Component layout and balance analysis • Controls
Presentation Outline
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ME 441 Summary
• A larger hull was designed to accommodate the Ground Penetrating Radar antennae and the various system components
• Air flow and lift calculations performed• New hull and skirt constructed and tested• Lift engine acquired• Lift fan selected and acquired• Thruster housing design modified and four units
constructed
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Ground Penetrating Radar
• Penetradar GPR system outfitted with IRIS processing software provided by U.S. Army Night Vision Directorate
• Test designed to observe its detection capabilities
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Navigation System
• Acquired differential GPS components (~3cm resolution) from U.S. Army Night Vision Directorate
• Will allow position and direction of the craft to be monitored from a remote location
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Pressure Testing
• Verification of lift and air flow calculations
• Used differential pressure transducer to measure static pressure inside the hull
• Average pressure measured was 0.16psi
• Predicted value was 0.19psi
• ~16% difference
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Lift Engine Mount
• Design objectives:– Maximize space efficiency– Support and restrain lift
engine while in operation
• Initial testing revealed significant vibration of engine, indicating deformation of the mount and potential fatigue failure
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Lift Engine Mount
• Additional element was added to bolster the engine’s supporting members and to reduce stress and resulting deformation
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Lift Engine Shroud• A shroud was designed and tested to protect
lift fan and people working around the craft• Able to withstand a person falling against it • Provides sufficient barrier between fingers and
moving components• Restricts large debris from encountering lift fan
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Overall Power SystemsFlow diagram for power systems
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Propulsion Power System
• Propulsion system requires 29.6 – 37V voltage supply
• Three 12V deep-cycle marine batteries in series provide necessary voltage
• 32V alternator donated by Prestolite Electric used to charge battery bank (charges at 38.5V)
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Electronics Power System
• GPR computer requires a 110-120V supply voltage
• 12V battery connected to self-exciting 12V alternator connected to 110-120V power inverter
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Pulley Attachment• Connection required between lift
engine and lift fan• Power systems design required
alternators to be driven by lift engine
• Fabricated part and completed analysis
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Thruster Testing• Pendulum apparatus allowed testing of various
thrust system parameters: • Motors• Propellers• Housing mesh
configurations
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Thruster Housing Mesh Tests• Housings would restrict air flow and thrust force• Modified mesh improved results • Both meshes required for safety parameters• Maximum force of ~15.67lbf
Mesh Configuration (with full housing)
Average Thrust Force Loss
(as compared to unhoused propeller)
Front and rear mesh 37.1%
Rear mesh only 18.1%
Front mesh only 23.7%
Modified front mesh only 13.0%
Modified both front and rear meshes
16.2%
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Motor Stand Strength Test
• Basic design of motor stand modified
• Maximum force produced by motor with housing is 15.67lbf
• Test performed by applying ~35lb force to stand with force gauge for 30 seconds
• No sign of deformation observed, therefore stand has at least a safety factor of 2
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Component Layout and Balance Analysis
• Components need to be arranged to minimize air flow impedance to thrusters and maximize balance of craft
• Used modeling software to arrange layout and assign component weights and calculate center of mass
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Component Layout and Balance Analysis
• Thrusters arranged to maximize forward and backward response
• Turning capability increased by placing center thrusters closer to outer units
• ~1ft of free space arranged between thruster units and other equipment, so air flow would not be obstructed
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Computer
• Single computer to operate controls, navigation system, and GPR for functionality
• Will utilize remote desktop so that systems can be operated from a removed location
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Requirements:-Control from external location-Move with 2DOF-Easily operable interface
Constraints:-Cost-Must use computer already on craft-4 Simultaneous motors-Signal must be a PWM square wave
Controls
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Laptop via remote desktop PC w/ GUI Microcontroller
Electric Motors
Controls
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Controls
Direction of airflow
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Controls
Direction of airflow
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Controls
Direction of airflow
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Controls
Direction of airflow
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Conclusions
• We produced a hovering craft that is capable of:• Carrying required lift and power components in
addition to navigation and detection equipment• Supplying power to the propulsion and electronics
systems
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Conclusions
• Tests were completed on each subsystem, for instance the propulsion system in which each unit is able to produce ~15.5lb of thrust force
• Controls, Ground Penetrating Radar and navigation systems need to be refined further
• A basic integrated test has been completed with all of the various systems
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For more information:http://students.cua.edu/51mcmahon/
Questions?