CDR October 9, 2008 Mike Oertli Jonathan Karnuth Jason Rancier
Division of Labor Mike O. Program MCU Matlab interface Jonathan K. Construct rails Assist in control system design and coding Jason R. Construct capacitor array Design voltage sensors
Block Diagram MSP430F169 Power Supply Keypad LCD Railgun Capacitor Array Kill Switch LEDs Inductor Voltage Sensor Pneumatic Starter System Encoder
Budget ItemQty. NeededCost PerTotal for item Brass Rails (36") Garolite G-10 (39") Teflon (12") Aluminum (12") Capacitors50Donated0.00 PCB Microcontroller20.00 Air compressor Air tank Solenoid Valve Pressure Regulator Transformer Plastic housing Sensors/Miscellaneous Grand Total1,038.70
Safety Features Voltage sensors on rails, cap bank, & source Kill power if out of expected range Plexiglas casing o Keep user isolated from high voltages and short circuited rails Pressure Regulator o Added ability to safely release tank pressure
Power System Diagram
Capacitor Battery 50x 450V 3.7mF Capacitor Donated by CDE Array of 3 banks of 16 in parallel Overall: 1350V ~ 20mF
Capacitor Battery
Basic Charger
Power Parts 2x 3W 1x W 50x 3 W 3x 50 W 1x 120V 15 Amp AC switch 1x Fuse Holder 120VAC 1x 1600v Power Diode 2x High Voltage Switch(1000V) 1x Microwave Transformer 1x Variac Variable Transformer Copper Plate Plexiglass Box
Cylindrical Rail Design Design Difficulties Material Tolerances Material Loss Toxic materials Difficult to machine at desired barrel length Efficient Design method Maintain physical contact despite material disintegration
Machined & Fabricated Parts
Compressed Air Injector Adapter
Injector Adapter Drawing
Brass Rails Composite: ~70% Copper, ~.07% Lead, ~.05% Iron, Remainder Zinc Electrical Conductivity: 28% IACS Electrical Resistance: 6.2µΩ/cm Friction: Very low with Most metals Melting Point: 910 o C Inner/Outer Diameter: 0.87”/1”
Projectile Metal: Aluminum Composite: 2011 Temper: T3 Part #: 88615K411 Melting point: 540 o C Electrical Conductivity: 45% IACS Electrical Resistivity: 3.8µΩ/cm Diameter: 7/8” Length: ~1”
Pneumatic Kick-start Avoids spot welding projectile Added kinetic energy Eliminates static friction coefficients Compressed Air system Activated by Microcontroller post safety checks Additional safety with inclusion of Pressure Regulator
Injection System
Complete System Compressed Air Tank Compressor Solenoid Valve Ball Valve Pressure Regulator Manufactured Parts Railgun Adapter Tank Adapter Compressor Adapter
Electromagnetic Solenoid Valve
Pressure Regulator Features High Pressure capabilities Very Low Flow 1/150 Flow of the Solenoid (.06 Cv) Adjustable Pressure Range Low leakage Value 3600 Psi Capabilities
Chassis Specs Inner SupportOuter Sheath CompositeTeflon PTFEGrade G-10/FR4 Crosswise Tensile Strength 3,900 PSI35,000 PSI Melting Point 335 o C ~384 o C Max Temp Dielectric Strength19.7MV/m15.7MV/m Inner/Outer Diameter.875”/1”1”/1.375” Cost$9.21 per 12”$92.16 for 39” Part #8547K298668K49
Parts List- Control System Voltage Sensor MM74C key encoder Keypad, 3-line LCD Master kill switch “Hot” switch
Parts List- MCU MSP430F169 2 ADC 1 RS232 Voltage regulator LEDs
Interfaces MSP430F169Matlab RS232 Key EncoderKeypadMSP430F169 Wire-wrap/Solder MSP430F169 P6 I/O (ADC) Voltage Sensor 3-Line LCDMSP430F169 Wire-wrap/Solder
Keypad Pin Layout
Key Encoder MM74C Key Debounce Continuous row scan
Keypad & Encoder Schematic
Keypad Demo
Software- MCU Language: C++ Inputs: Keypad (via encoder chip on P1), voltage sensors (1 on ADC on P6, 2 nd via off board ADC), power (6V) Outputs: 3-line LCD (P2), Matlab (RS232), capacitor charging control (switch based on sensors), safety/kill switch
MCU Logic
Software- Matlab Plot time domain analysis of sensor readings Keep test-run information Inputs: Data from MSP Outputs: GUI showing data Interface: RS232
Questions?