Instrumented Football HelmetReliability & Safety

Failure Rate CalculationChoose 3-5 components:PIC18F45K20 MicrocontrollerMatchport Wireless AdapterTPS75733 LDOLTC3440 Buck/Boost5169UBBP01 Lithium Ion Battery

Failure Rate Calculation

Failure Rate CalculationPIC18F45K20 Microcontroller

ParameterDescriptionValueC1Die complexity failure rate (MOS)0.14TTemperate coefficient0.60C2Package failure rate0.2144EEnvironment factor4.0QQuality factor10.0LLearning factor2.0p18.832

FMECAFunctional BlocksPower SupplyMicrocontroller PowerMicrocontrollerMatchport PowerMatchportAccelerometers

Power Supply

Power Supply

Failureno.Failure modePossible causeFailure effectsMethod of detectionCriticalityA1Output = 0VFailure of any component or an external shortRest of helmet does not functionObservationLowA2Output > 4.2 VFailure of U25 or U19 and D12Possible damage to rest of circuitryObservationLowA4Battery Charge Voltage out of specFailure of U19Damage to battery, possibly a fireObservationHighA5Output out of ToleranceU23, C21, C22Unpredictable operationObservationLow

Microcontroller Power

Microcontroller Power

Failureno.Failure modePossible causeFailure effectsMethod of detectionCriticalityB15V Ouput = 0VU26, L1, D8Accelerometers stop functioning, no alerts sentObservationMediumB25V Ouput out of ToleranceC9, C10, L1Stored data is inaccurate and unpredictable alarmsObservationMediumB33.3 V Ouput = 0VU28 or external shortSystem does not workObservationLowB43.3V Ouput > 3.3VU28Damage to SD card, possibly fireObservationHighB53.3V Ouput out of ToleranceC14, C16, L3Some data not storedObservationLowB60.5V, 4.5V Output out of ToleranceR1, R2, R3Incorrect accelerometer measurements storedObservationLow

Microcontroller

Microcontroller

Failureno.Failure modePossible causeFailure effectsMethod of detectionCriticalityC1TestAcc1-3 continuously 1Software, short/open-circuit in microAccelerometers constantly in self-test modeObservationLowC2SD_CS continuously 1, 0Software, SPI peripheral failNo data saved/read from SD cardObservationLowC3MP_CP1-4 continuously 1Software, short in microMatchport may continuously send false alertsObservationLowC4MP_CP1-4 continuously 0Software, open-circuit in microMatchport will never send alertsObservationMedium

Matchport Power

Matchport Power

Failureno.Failure modePossible causeFailure effectsMethod of detectionCriticalityD1Ouput = 0VU28 or external shortMatchport stops functioningObservationMediumD2Ouput > 3.3VU28Damage to Matchport, possibly fireObservationMediumD3Ouput out of ToleranceC14, C16, L3Unpredictable Matchport operationObservationMedium

Matchport

Matchport

Failureno.Failure modePossible causeFailure effectsMethod of detectionCriticalityE1No wireless connectionDamage to Matchport, improperly configuredNo wireless device found for connectionObservationMediumE2No data over serial connectionDamage to Matchport, improperly setup web server, softwareData changed/requested on wireless connection are not set/sentObservationLow

Acclerometers

Accelerometers

Failureno.Failure modePossible causeFailure effectsMethod of detectionCriticalityF1Status output continuously highU5 failureSoftware will enter infinite loop during startupObservationLowF2Status output continuously lowU5 failureAccelerometer self-test will not workObservationLowF3X,Y,Z out continuously highAccX, AccY, AccZ failureWarnings for high-geforce impacts are sentObservation using self-testLowF4X,Y,Z out continuously lowAccX, AccY, AccZ failureWarnings for high-geforce impacts are sentObservation using self-testLowF5X,Y,Z out continuously middle (~2.5V)AccX, AccY, AccZ failureNo warnings for high-geforce impacts are sentObservation using self-testMedium