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RailTech PDR

RailTech PDR. Group Members: Mike Oertli Jonathan Karnuth Jason Rancier September 11, 2008. Project Overview. Linear accelerator Voltage applied to rails Projectile shorts out rails creating EM field Pneumatic kick-start Projectile accelerates forward. Basic Design.

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RailTech PDR

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  1. RailTechPDR Group Members: Mike Oertli Jonathan Karnuth Jason Rancier September 11, 2008

  2. Project Overview • Linear accelerator • Voltage applied to rails • Projectile shorts out rails creating EM field • Pneumatic kick-start • Projectile accelerates forward

  3. Basic Design • Conducting rails mounted to non-conducting surface • Capacitor array • PCB, logic, and UI • Conducting metallic projectile

  4. Objectives • Safety!!! • Adjustable voltage from capacitor bank • User interface • Keypad and LCD • Sensor data • Velocity calculations • Remote/Hands off (Safety!)

  5. Approach • Split into 3 main areas • Railgun • Control system • User interface • Each person focus on one area • Communication and compatibility is key

  6. Power Supply • Brute Force discharge • Basic supply, dumps a lot of current directly on rails • Simple to design, overkill on capacitance • Inefficient, back EMF problems • Recharger Supply • Complex LC timing based on rails • Prone to failure with bad design • Requires more capacitors (if polarized are used) • Much more efficient • Fast recharging

  7. Capacitors • Capacitance: 610,000µF • Voltage: 20VDC • 30VDC surge • ESR: 2.1mΩ max • Type: Electrolytic • Number used: ~20 • Cost: ~ $400

  8. Capacitor Array • Mounted capacitors • Connected by switches controlled by logic based on input voltage from user • Logic will be based on test shots • In enclosed case (Safety) • Other possibilities: • Manual switches • Switch mode power supply • Input inductor between array and rails • Ramps current to rails • Avoid discharging capacitors too fast

  9. Rail types • Cylindrical • Easier to fabricate • Fewer pieces • Stronger using less material • Rectangular • Easier to mount • Better electrical properties, distributed current

  10. Example of rail Conducting rails

  11. Materials • Rails: Brass • Projectile: Aluminum • Base: Garolite & Teflon • Capacitors: 20x 0.6F 20 v Electrolytic • Microcontroller: MSP430 family - 16 bit • PCB • Power supply • Sensors (EM, voltage) • Keypad and LCD

  12. 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: 910oC • Inner/Outer Diameter: 0.87”/1” • Cost: $58.68 for 36”

  13. Projectile • Metal: Aluminum • Composite: 2011 • Temper: T3 • Part #: 88615K411 • Melting point: 540oC • Electrical Conductivity: 45% IACS • Electrical Resistivity: 3.8µΩ/cm • Diameter: 7/8” • Length: ~1” • Cost: $17.41/foot

  14. Pneumatic Kick-start • Avoids spot welding projectile • Added kinetic energy • Eliminates static friction coefficients • Compressed Air/CO2 system • Activated by Microcontroller post safety checks

  15. Chassis Specs

  16. Safety Features • Voltage sensors on rails, cap bank, & source • Kill power if out of expected range • EM Field Sensor • Faraday cage if EM field great enough • Plexiglas casing • Keep user isolated from high voltages and short circuited rails

  17. Block Diagram Capacitor Array Inductor Rails Power Supply Kill Switch Keypad LEDs MSP430xxxx LCD

  18. Microcontroller • MSP430xxxx family • Testing on MSP430F169 • 16-bit for accurate calculation of sensor data • Control safety logic based on sensor values • Disconnect switches from caps to rails • Display values on LCD

  19. Software Engineering • Interface with Matlab • Import sensor data • Statistical analysis • Display results to user as graphs and tables • Maintain records

  20. PCB Elements • Power supply • MSP430 Family • Debug/information LEDs • LCD (3 or 4 rows) • Keypad input • Communication with sensors(A/D)

  21. Sensor • Measure voltage at high sample rate • Used for analysis and safety logic • Implementation: • Voltage transducer • Sample @ 10 MHz + • Response time < 50μs

  22. User Interface • Basic keypad • Input desired voltage to apply to rails • 3 or 4 line LCD on PCB • Output sensor data and statistics • Basic input user interface • If time: • Keyboard input • Computer monitor with GUI • Matlab sensor data analysis

  23. Expenses

  24. Division of Labor

  25. Schedule

  26. “Real World” Application • Control System for other high voltage applications • Accelerator for fun, military, other scientific research • Capacitor array for high current burst power systems • Sensor to Matlab interface

  27. Realization • Stay under budget by getting donations • Establish primary goals/reasonable functionality • Operate within these • Add incremental levels of difficulty based on time

  28. Plan B • Risk: • Projectile fuses to rails • Discontinuities in the rails and base • Arcing- heat/damage to rails • Unfamiliarity • Sensing systems • Matlab interface • Recovery • Ask for help! • Use heavier duty components • RTFM • Have extra rails and projectiles ready

  29. Questions?

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