CDR October 9, 2008 Mike Oertli Jonathan Karnuth Jason Rancier
Division of LaborMike O.
Program MCUMatlab interface
Jonathan K.Construct railsAssist in control system design and coding
Jason R.Construct capacitor arrayDesign voltage sensors
Block Diagram
MSP430F169
Power Supply
Keypad
LCD
Railgun
Capacitor Array
KillSwitch
LEDs
Inductor
Voltage Sensor
Voltage Sensor
Pneumatic Starter System
Encoder
Item Qty. Needed Cost Per Total for item
Brass Rails (36") 2 58.68 117.36
Garolite G-10 (39") 1 92.16 92.16
Teflon (12") 6 9.21 55.26
Aluminum (12") 2 17.41 34.82
Capacitors 50 Donated 0.00
PCB 2 33.00 66.00
Microcontroller 2 0.00 0.00
Air compressor 1 56.10 56.10
Air tank 1 62.00 62.00
Solenoid Valve 1 170.00 170.00
Pressure Regulator 1 35.00 35.00
Transformer 1 100.00 100.00
Plastic housing 1 50.00 50.00
Sensors/Miscellaneous 200.00
Grand Total 1,038.70
Safety FeaturesVoltage sensors on rails, cap bank, &
sourceKill power if out of expected range
Plexiglas casingo Keep user isolated from high voltages and
short circuited rails
Pressure Regulatoro Added ability to safely release tank pressure
Capacitor Battery50x 450V 3.7mF Capacitor
Donated by CDEArray of 3 banks of 16 in parallel
Overall: 1350V ~ 20mF
Power Parts2x 200KOmh @ 3W1x 800Omh @ .25 W50x 100kOmh @ 3 W3x 22KOmh @ 50 W1x 120V 15 Amp AC switch1x Fuse Holder 120VAC1x 1600v Power Diode2x High Voltage Switch(1000V)1x Microwave Transformer1x Variac Variable TransformerCopper PlatePlexiglass Box
Cylindrical Rail DesignDesign Difficulties• Material Tolerances• Material Loss• Toxic materials• Difficult to machine at
desired barrel length
Efficient Design method• Maintain physical contact despite material disintegration
Brass RailsComposite: ~70% Copper, ~.07% Lead,
~.05% Iron, Remainder ZincElectrical Conductivity: 28% IACSElectrical Resistance: 6.2µΩ/cmFriction: Very low with Most metalsMelting Point: 910oCInner/Outer Diameter: 0.87”/1”
ProjectileMetal: Aluminum
Composite: 2011Temper: T3Part #: 88615K411
Melting point: 540oC Electrical Conductivity: 45%
IACSElectrical Resistivity: 3.8µΩ/cmDiameter: 7/8”Length: ~1”
Pneumatic Kick-start Avoids spot welding projectile
Added kinetic energy
Eliminates static friction coefficients
Compressed Air systemActivated by Microcontroller post safety checks
Additional safety with inclusion of Pressure Regulator
Complete SystemCompressed Air
TankCompressorSolenoid ValveBall ValvePressure RegulatorManufactured Parts
Railgun Adapter Tank Adapter Compressor Adapter
Pressure RegulatorFeatures
High Pressure capabilities
Very Low Flow
1/150 Flow of the Solenoid (.06 Cv)
Adjustable Pressure Range
Low leakage Value
3600 Psi Capabilities
Chassis SpecsInner Support Outer Sheath
Composite Teflon PTFE Grade G-10/FR4
Crosswise Tensile Strength
3,900 PSI 35,000 PSI
Melting Point 335oC ~384oC Max Temp
Dielectric Strength 19.7MV/m 15.7MV/m
Inner/Outer Diameter
.875”/1” 1”/1.375”
Cost $9.21 per 12” $92.16 for 39”
Part # 8547K29 8668K49
Parts List- Control SystemVoltage SensorMM74C922 16 key encoderKeypad, 3-line LCDMaster kill switch“Hot” switch
InterfacesMSP430F169 Matlab
RS232
Key Encoder KeypadMSP430F169Wire-wrap/Solder Wire-wrap/Solder
MSP430F169P6 I/O (ADC)
Voltage Sensor
3-Line LCDMSP430F169Wire-wrap/Solder
Keypad Pin LayoutTruth Table
Pins 2 4 12 13
1 1 2 3 ST
3 4 5 6 PT
14 7 8 9 TI
5 CL 0 FX PI
1 2 3 4 5 6 7
14 13 12 11 10 9 8
Software- MCULanguage: C++Inputs: Keypad (via encoder chip on P1),
voltage sensors (1 on ADC on P6, 2nd via off board ADC), power (6V)
Outputs: 3-line LCD (P2), Matlab (RS232), capacitor charging control (switch based on sensors), safety/kill switch
Software- MatlabPlot time domain analysis of sensor readingsKeep test-run informationInputs: Data from MSPOutputs: GUI showing dataInterface: RS232