Download Reliability & Safety

Instrumented Football Helmet
Reliability & Safety
Failure Rate Calculation
Choose 3-5 components:
•
PIC18F45K20 Microcontroller
•
Matchport Wireless Adapter
•
TPS75733 LDO
•
LTC3440 Buck/Boost
•
5169UBBP01 Lithium Ion Battery
Failure Rate Calculation
Failure Rate Calculation
PIC18F45K20 Microcontroller
Parameter
Description
Value
C1
Die complexity failure rate (MOS)
0.14
πT
Temperate coefficient
0.60
C2
Package failure rate
0.2144
πE
Environment factor
4.0
πQ
Quality factor
10.0
πL
Learning factor
2.0
λp
18.832
FMECA
Functional
•
•
•
•
•
•
Blocks
Power Supply
Microcontroller Power
Microcontroller
Matchport Power
Matchport
Accelerometers
Power Supply
Power Supply
Failure
no.
Failure effects
Method of
detection
Criticality
Output = 0V
Failure of any
component or an
external short
Rest of helmet does
not function
Observation
Low
Output > 4.2 V
Failure of U25 or U19
and D12
Possible damage to
rest of circuitry
Observation
Low
Battery Charge
Voltage out of
spec
Failure of U19
Damage to battery,
possibly a fire
Observation
High
Output out of
Tolerance
U23, C21, C22
Unpredictable
operation
Observation
Low
Failure mode
A1
A2
A4
A5
Possible cause
Microcontroller Power
Microcontroller Power
Failure
no.
Failure effects
Method of
detection
Criticality
U26, L1, D8
Accelerometers stop
functioning, no alerts
sent
Observation
Medium
5V Ouput out of
Tolerance
C9, C10, L1
Stored data is
inaccurate and
unpredictable alarms
Observation
Medium
3.3 V Ouput = 0V
U28 or external
short
System does not work
Observation
Low
3.3V Ouput > 3.3V
U28
Damage to SD card,
possibly fire
Observation
High
3.3V Ouput out of
Tolerance
C14, C16, L3
Some data not stored
Observation
Low
R1, R2, R3
Incorrect
accelerometer
measurements stored
Observation
Low
Failure mode
Possible cause
B1
5V Ouput = 0V
B2
B3
B4
B5
B6
0.5V, 4.5V Output
out of Tolerance
Microcontroller
Microcontroller
Failure
no.
C1
C2
C3
C4
Possible cause
Failure effects
Method of
detection
Criticality
TestAcc1-3
continuously 1
Software,
short/open-circuit
in micro
Accelerometers
constantly in self-test
mode
Observation
Low
SD_CS
continuously 1, 0
Software, SPI
peripheral fail
No data saved/read
from SD card
Observation
Low
MP_CP1-4
continuously 1
Software, short in
micro
Matchport may
continuously send
false alerts
Observation
Low
MP_CP1-4
continuously 0
Software, opencircuit in micro
Matchport will never
send alerts
Observation
Medium
Failure mode
Matchport Power
Matchport Power
Failure
no.
D1
D2
D3
Failure mode
Possible cause
Ouput = 0V
U28 or external
short
Ouput > 3.3V
U28
Ouput out of
Tolerance
C14, C16, L3
Failure effects
Method of
detection
Criticality
Matchport stops
functioning
Observation
Medium
Damage to Matchport,
possibly fire
Observation
Medium
Unpredictable Matchport
operation
Observation
Medium
Matchport
Matchport
Failure
no.
E1
Failure mode
No wireless
connection
Possible cause
Failure effects
Method of
detection
Criticality
Damage to Matchport,
improperly configured
No wireless device
found for connection
Observation
Medium
Damage to Matchport,
improperly setup web
server, software
Data
changed/requested
on wireless
connection are not
set/sent
Observation
Low
E2
No data over
serial connection
Acclerometers
Accelerometers
Failure
no.
F1
Failure mode
Status output
continuously
high
F2
F3
F4
F5
Possible cause
Failure effects
Method of
detection
Criticality
U5 failure
Software will enter
infinite loop during
startup
Observation
Low
Status output
continuously low
U5 failure
Accelerometer selftest will not work
Observation
Low
X,Y,Z out
continuously
high
AccX, AccY, AccZ
failure
Warnings for highgeforce impacts
are sent
Observation
using self-test
Low
X,Y,Z out
continuously low
AccX, AccY, AccZ
failure
Warnings for highgeforce impacts
are sent
Observation
using self-test
Low
X,Y,Z out
continuously
middle (~2.5V)
AccX, AccY, AccZ
failure
No warnings for
high-geforce
impacts are sent
Observation
using self-test
Medium