Doodle Drive

Doodle Drive

Doodle DrivePresenter: Peachanok Lertkajornkitti

Team 6Reliability and Safety AnalysisProject OverviewAndroid application as controllerRobot vehicle with microcontrollerPath will be drawn in Android application and the vehicle will follow that pathOutdoor mode with GPS, Google Maps, CompassIndoor mode with tilt control

Criticality levelsLow:Minor failures that doesnt cause any physical damage to userDoesnt cause any damage to the PCBE.g. Reading errors

Medium:Cause physical damage to the PCB or the vehicleE.g. Damage of the components due to overheating, inability to control the vehicleHigh:Cause injury to user/people aroundE.g. Burn due to touching the components that overheatsComponents for analysisMicrocontroller (LPC1768)Complex100 pins , 32-bitTj = 50 C = 2.904 e -6MTTF: 40 yearsFirst of all, I choose the Microcontroller as the possible choice of component that could fail.4Components for analysisVoltage Regulators (LM2596)High temperature (but with good heat sink)Tj = 25 C = 1.44e -7MTTF: 792 yearsComponents for analysisH-BridgeHigh voltage and currentHigh junction temperatureTj = 75 C = 6.6e-7MTTF: 171 years

Components for analysisCompassMEMS (Micro-Electro-Mechanical Systems) less reliable than ICsTj = 25 C = 5e-7MTTF: 228 years

Block Diagram

PWMAs you can see, all the components to operate this vehicle are all dependent on the microcontroller. So, if the microcontroller fails, it will greatly affect the performance of the vehicle. 8FMECAMicrocontroller

Failure ModePossible CauseFailure EffectsCriticalityPWM Signal FailurePWM pins failure Servo and H-Bridge will not work Vehicle unable to move Unable to swing the ultrasonic sensors

LowUART Signal FailureUART pins failure No GPS and Bluetooth communication.LowI2C Signal FailureI2C pins failure Compass failureLowGPIO Signal FailureGPIO pins failure Ultrasonic sensors failure Fuel Gauge failureLow - MediumFailure Modes and Effects Criticality Analysis. Very low criticality level even if it fails.9FMECACompassFailure ModePossible CauseFailure EffectsCriticalityCompass failureR1 & R2 failure (Pulled up resistors)Incorrect reading of the compass

LowFMECAH-BridgeFailure ModePossible CauseFailure EffectsCriticalityMotor driver failsD3 D10, C10. Unpredictable behavior of the vehicles movementMedium - LowFMECAVoltage Regulators (3.3V and 5V)Failure ModePossible CauseFailure EffectsCriticalityVout = 0VL2, C4, D2, C3 Components using the 3.3V regulators will not operate.LowVout > 3.3V

Vout > 5VC4 (3.3V) or C2 (5V) Overheating of componentsHigh cause burn when touchedVout unpredictableL2, C4, D2, C3 Unpredictable behavior of components 5V ultrasonic sensors and servo 3.3V compass, GPS, Bluetooth etc.Medium unable to control the vehicleTHANK YOU!Questions / Discussions

MicroController1: Compass (I2C)2: Bluetooth (UART)3: GPS (UART)4: H-Bridge (PWM, GPIO)5: Ultrasonic (GPIO)6: Optical Encoders (Input Capture, GPIO)7: Crystal Oscillator8: Fuel Gauge (GPIO)9: Servo (PWM)13782495614H-BridgE

Hbridge. We currently have two 100nF capacitors for bypass (as specified by datasheet). For each motor, it takes in one gpio (enable) and two pwm channels (for controlling operation). We could connect sense resistors at SENSE_A and SENSE_B and have a pin monitoring the voltage at those so we know the current theyre using, but we arent doing that right now. You can see to the left two headers for each motor, as well as four flyback diodes that are used for protection (not internal to L298)15COMPASS

Heres the compass the symbol looks a little odd but its this way because were actually using a breakout board for it (you can see this better on the PCB) because the IC itself is incredibly small. The breakout board has a bypass capacitors on it already. All thats connected is the two pullup I2C resistors. There are a lot of unused pins, mainly because this device is more feature heavy than we need and actually has an accelerometer too.16VOLTAGE REGULATORS

5V powers the ultrasonic sensors and optical encoder. 3.3V powers pretty much everything else.17