Defender Safety and Reliability Analysis Kirk Iler Brian Bentz Stephen Wolf Fuhe Xu

Issues Coilgun Backfire – Coilguns have a possibility of shooting payload backwards through barrel Signals triggering on noise – Improper filtering can lead to coilgun commands given through packet sending Capacitor/Power Malfunction – 400V Electrolytic capacitors are capable of causing explosions if misused – High Voltage power supply used

Potential for Failure Motor Micro – DRV8821 – Overheat – Hard Stop, loss of control 12V Power Supply – LM – Heat Dissipation (.3W at 3.3V) Microcontroller – PIC24FJ64GB004 Firing IGBT – APT200GN60JDQ4MI-ND – Current (400 A) Capacitors – U32D 400V Electrolytic – Lifetime measurement

Subsystem Definitions High Voltage Capacitor Microcontroller Atom Motor

FMECA Failure No.Failure ModePossible Causes Failure EffectsMethod of Detection Criticality High Voltage A1Low VoltageInput from transformer is too low Unable to operate ObservationLow A2Excessive Voltage Capacitor breaks, excess input from transformer Component destruction, Injury ObservationHigh Capacitors B1ShortBreakdown of dielectric Explosion, Injury ObservationHigh

FMECA Failure No.Failure ModePossible Causes Failure EffectsMethod of Detection Criticality Microcontroller C1Low VoltageBypass capacitors failed Not operatingObservationLow C2Discharge Timing Delay loop timed incorrectly Projectile misfires ObservationHigh Atom D1No instructions to Micro USB Connection failure Unable to control motors or coilgun Observation Micro Debugging Low

Failure No.Failure ModePossible Causes Failure EffectsMethod of Detection Criticality Motors E1OverheatingExcess Current Motors shut down ObservationMedium E2Full stopControl Timing Missed Loss of motor control ObservationMedium FMECA

Mitigation Power Systems – Fuses – Diode on capacitors – Parts can go into Thermal Shutdown Coilgun – Metal posts to control maximum rotation – Stop in barrel to prevent reverse