Heavy Vehicle Event Data Recorders NTSS 2013 http://tucrrc.utulsa.edu 1
HOW EVENTS GET SET IN AN ENGINE CONTROL MODULE NTSS 2013 http://tucrrc.utulsa.edu 2
Overview Vehicle Speed Data Vehicle Networking J1708/J1587 J1939 and Controller Area Networks Synchronized Testing Results Network Data, EDR Data, and GPS Data Out-of-service brakes Review of TUCRRC Website Content Digital Forensics for HVEDRs NTSS 2013 http://tucrrc.utulsa.edu 3
Electronic Control Modules A computerized system that controls the operation of different aspects of the vehicle. Engine Control Module (ECM) Electronic Brake Controller (EBC) Automatic Transmission Controller Body Controller GPS and Telematics Unit Collision Avoidance Systems Potentially a dedicated Event Data Recorder Definition in SAE J2728: An electronic control unit (ECU) is an electronic subsystem that manages the functions of a vehicle system or components. ECUs are often called electronic control modules, or ECMs, or simply modules. NTSS 2013 http://tucrrc.utulsa.edu 4
We can t work with this one NTSS 2013 http://tucrrc.utulsa.edu 5
Missing Data?? NTSS 2013 http://tucrrc.utulsa.edu 6
Event Data Types of ECM Data Sudden deceleration (e.g. decrease of 7 mph/s) Last Stop trigger Diagnostic trigger Fault Freeze Frame Data Historical Data Recorded by ECM for Use Configuration Data Programmed into ECM NTSS 2013 http://tucrrc.utulsa.edu 7
Pavement to EDR Data Wheels Turn VSS Signal Generated ECM Calculates Speed Data Transmitted on Network NTSS 2013 http://tucrrc.utulsa.edu 8
Sensing Speed A magnetic pick-up uses variable reluctance to sense the rotation of the tailshaft. Tailshaft Magnetic Pickup Tailshaft Transmission Tone Ring Transmission NTSS 2013 http://tucrrc.utulsa.edu 9
Vehicle Speed Sensor 16 Tooth Tone Ring NTSS 2013 http://tucrrc.utulsa.edu 10
Pavement to EDR Data Wheels Turn VSS Signal Generated ECM Calculates Speed Data Transmitted on Network NTSS 2013 http://tucrrc.utulsa.edu 11
Speed Sensing In Action NTSS 2013 http://tucrrc.utulsa.edu 12
Peak to-peak, Vpp Describing a Signal 1000 edaq-ddec6testingwithhathaway.sie - ToneRing@WheelSpeed.RN_1 WheelSpeed(millivolts) 500 0-500 -1000-1500 -2000 Period, T Frequency (Hz) = 1/T 212.26 212.28 212.30 212.32 212.34 Time(secs) NTSS 2013 http://tucrrc.utulsa.edu 13
Amplitude Describing a Signal (Cont.) 1000 edaq-ddec6testingwithhathaway.sie - ToneRing@WheelSpeed.RN_1 WheelSpeed(millivolts) 500 0-500 -1000-1500 Offset DC Value or Mean Value -2000 212.26 212.28 212.30 212.32 212.34 Time(secs) NTSS 2013 http://tucrrc.utulsa.edu 14
Actual Vehicle Speed Sensor Signals Wire pierce near the sensor Record with the Analog In feature of the edaq. Exhaust Signal Wires NTSS 2013 http://tucrrc.utulsa.edu 15
Example of Actual Speed Sensor Signal Speed (MPH) 30 20 10 0-10 -20-30 -40-50 -60-70 VSS Tone Ring Signal (0.1 V) GPS Based Vehicle Speed (MPH) VSS Check Pulses 245 250 255 260 Time(secs) NTSS 2013 http://tucrrc.utulsa.edu 16
Example of Actual Speed Sensor Signal (Zoomed) Speed (MPH) 30 20 10 0-10 -20-30 -40-50 -60-70 VSS Tone Ring Signal (0.1 V) GPS Based Vehicle Speed (MPH) x:255.30171 y:-10.3896 n:2302543 x:255.33927 y:-10.3927 dx:0.037 x:255.3 y:24.0398 n:18420 6 pulses in 0.03756 seconds with 2.93 gears and 19.5 inch radius = 23.7 mph (GPS = 24.04 mph) x:255.34 y:24.0709 dx:0.04 dy: 255.31 255.32 255.34 Time(secs) NTSS 2013 http://tucrrc.utulsa.edu 17
Example of Actual Speed Sensor Signal (Starting) 10 VSS Tone Ring Signal (0.1 V) GPS Based Vehicle Speed (MPH) 5 Speed (MPH) 0-5 -10-15 -20-25 247.0 247.5 248.0 Time(secs) NTSS 2013 http://tucrrc.utulsa.edu 18
Example of Actual Speed Sensor Signal (Stopping) 10 VSS Tone Ring Signal (0.1 V) GPS Based Vehicle Speed (MPH) 5 0 Speed (MPH) -5-10 -15-20 -25-30 Gap shows tire stick-slip when finishing -35 259.0 259.5 260.0 260.5 Time(secs) NTSS 2013 http://tucrrc.utulsa.edu 19
Speed Sensing Observations Amplitude of the signal increases with speed. Frequency of the signal increases with speed. Peak to Peak may go from 10 mv to over 10 V. May not be referenced to common ground. NTSS 2013 http://tucrrc.utulsa.edu 20
Pavement to EDR Data Wheels Turn VSS Signal Generated ECM Calculates Speed Data Transmitted on Network NTSS 2013 http://tucrrc.utulsa.edu 21
Determining Speed A Signal Conditioning chip converts the analog signal into a pulse train. NTSS 2013 http://tucrrc.utulsa.edu 22
Determining Speed (Cont.) The ECM counts the number of pulses in a given unit of time, say 0.1 seconds. The number of pulses is converted to a distance using pulses per mile (ppm). Example: 60 pulses in 0.1 seconds. 60 pulses 0.1 sec mile 29126 pulses 3600 sec 1 hour = 74.1 mph NTSS 2013 http://tucrrc.utulsa.edu 23
Getting Pulses Per Mile Ask the Engine Control Module: J1587 PID 228: Speed Sensor Calibration Software output (DDDL shown here) 3.700 x 16 x 492 = 29126.4 ppm NTSS 2013 http://tucrrc.utulsa.edu 24
Confirming Pulses Per Mile Physically Inspect the Vehicle Component Information (maybe in the glovebox) Tells what components to expect 3.70 NTSS 2013 http://tucrrc.utulsa.edu 25
Axle Tag Shows Gear Ratio Tag may not be readable. This one says RATIO 00370. Look for signs of repair. NTSS 2013 http://tucrrc.utulsa.edu 26
Estimate Rolling Radius Method 1: Level and Tape Measure Measure from center to ground of drive wheels Typical ~19.5-21 inches Circumference = 3.1415 x 2 x radius, which has units of inches per revolution Method 2: Mark the drive wheels and direct measure circumference Put grease on the tread and measure the spacing of the grease mark on the pavement NTSS 2013 http://tucrrc.utulsa.edu 27
Looking Up Rolling Radius Example:Google michelin truck tire data book http://www.tiregroup.c om/catalogs/pdf%20c atalogs/michelin.pdf Other manufacturers have similar data NTSS 2013 http://tucrrc.utulsa.edu 28
Looking Up Rolling Radius NTSS 2013 http://tucrrc.utulsa.edu 29
Measuring Rolling Radius SAE J1025 to get Revolutions per mile Long distance controlled tests 1.5% Accuracy According to the Michelin Truck Tire Service Manual, The accuracy of the tire revolutions per mile number is +/- 1% NTSS 2013 http://tucrrc.utulsa.edu 30
Calculating Revs Per Mile Multiply by the gear ratio and number of teeth to get Pulses Per Mile (492)(3.7)(16) = 29126.4 ppm NTSS 2013 http://tucrrc.utulsa.edu 31
What if our rolling radius estimate is off? If Rolling Radius = 20.5 inches, 600 pulses in 1 second gives 74.16 mph If Rolling Radius is 19.5 inches, 600 pulses in 1 second gives 70.57 mph Difference of 3.59 mph is about 5%. Differences magnitudes are less for lower speeds Pavement type and tread geometry have minor effects NTSS 2013 http://tucrrc.utulsa.edu 32
Other Factors Affecting Speed Heavier Load -> Smaller Rolling Radius -> Lower Speed Low Tire Pressure -> Smaller Rolling Radius -> Lower Speed Treadwear -> Smaller Rolling Radius -> Lower Speed Tire Slip When Braking -> Less Revolutions -> Lower Speed Tire Slip Under Power -> More Revolutions -> Higher Speed NTSS 2013 http://tucrrc.utulsa.edu 33
Pavement to EDR Data Wheels Turn VSS Signal Generated ECM Calculates Speed Data Transmitted on Network Sine Sine 1 0.8 0.6 0.4 0.2 0-0.2-0.4-0.6-0.8-1 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 Time 0.1 NTSS 2013 http://tucrrc.utulsa.edu 34
Simulating Our Own Speeds Use a function generator to insert signals on the Vehicle Speed Sensor (VSS) circuit. Only frequency matters NTSS 2013 http://tucrrc.utulsa.edu 35
Result: Truck-in-a-box NTSS 2013 http://tucrrc.utulsa.edu 36
Overall System NTSS 2013 http://tucrrc.utulsa.edu 37
Pavement to EDR Data Wheels Turn VSS Signal Generated ECM Calculates Speed Data Transmitted on Network NTSS 2013 http://tucrrc.utulsa.edu 38
Simplify Wiring Heavy Vehicle Networks Enables multiple systems on one bus Data sharing between ECUs External interface with 6 or 9-pin connector NTSS 2013 http://tucrrc.utulsa.edu 39
Network Standards SAE J1708 and J1587 Based on a 9600 baud RS-485 connection Similar to the serial port on a computer Phased out, but still on the road (DDEC 4 and 5, Cat ADEM3) SAE J1939 Based on a 250,000 baud Controller Area Network (CAN) connection CAN is used on passenger cars too. NTSS 2013 http://tucrrc.utulsa.edu 40
J1708 Network Messages Speed signals are interpreted and broadcast as serial messages in frames. J1708 Frame: MID: Message Identifier 128 (0x80) for Engine 183 (0xB6) for Off-board Programming Station PID: Parameter Identification 84 (0x54) for Road Speed 190 (0xBE) for Engine Speed MID PID DATA Checksum NTSS 2013 http://tucrrc.utulsa.edu 41
Interpreting J1708 Data Use J1587 as the roadmap NTSS 2013 http://tucrrc.utulsa.edu 42
Example Speed Data J1708 Hex Serial Data is found in a log file: Line Abs Time(Sec) Rel Time (Sec) Er Tx Description MID PID DATA 24723 538.7992186 0.005920976 F F J1708 $80 80 54 37 MID: Engine PID: Road Speed Determine Decimal (55 in this case) Multiply by 0.5 (27.5 in this case) Append units from J1587: 27.5 mph NTSS 2013 http://tucrrc.utulsa.edu 43
Converting Hex to Decimal Excel: =HEX2DEC( 37 ) Windows Calculator: NTSS 2013 http://tucrrc.utulsa.edu 44
There are 10 types of people in this world: Those that understand binary and those that don t. NTSS 2013 http://tucrrc.utulsa.edu 45
Why does this matter? The SAE Standards explain many of the parameters in the EDR reports. Can not expect better than 0.5 mph accuracy on J1708 based vehicles. Network traffic reflects ECU computed data If network traffic is accurate, then EDR data is likely accurate. Network data is the source for telematics units (e.g. Qualcomm). Enables assessment without the need to set events. More data samples NTSS 2013 http://tucrrc.utulsa.edu 46
Controller Area Networks Controller Area Network (CAN) serial bus introduced by Bosch in 1986 A 2-wire bus with multi-master capability with Collision Detection, Arbitration, and Error Checking Result: nearly 100% data integrity in harsh environments Implemented using CAN transceiver hardware Motorola / Microchip Amtel Freescale Semiconductors NTSS 2013 http://tucrrc.utulsa.edu 47
CAN Messages 29-bit Identifier (Arbitration) Control Field Data Field Error Checking Data typically transferred up to 8 bytes at a time NTSS 2013 http://tucrrc.utulsa.edu 48
SAE J1939 Built on CAN at 250,000 bits/s Fast enough for real-time control Uses the message identifier to define purpose. Defines everything from physical connections to diagnostic applications. Provides the basis for understanding and interpreting some of the data. NTSS 2013 http://tucrrc.utulsa.edu 49
J1939 Connector (9-Pin) Pin A: Battery (-) Pin B: Battery (+) Pin C: CAN High Pin D: CAN Low Pin E: CAN Shield Pin F: J1708 (+) Pin G: J1708 (-) Pin H: OEM Use or 2 nd CAN High Pin J: OEM Use or 2 nd CAN Low NTSS 2013 http://tucrrc.utulsa.edu 50
Data Acquisition and APPLICATIONS TO HEAVY VEHCILES NTSS 2013 http://tucrrc.utulsa.edu 51
Vehicle Description 2008 Freightliner Single Drive Axle DDEC VI equipped Detroit Diesel Series 60 Engine Eaton 10 Speed Manual 2.93:1 Rear Axle Ratio NTSS 2013 http://tucrrc.utulsa.edu 52
Component Information NTSS 2013 http://tucrrc.utulsa.edu 53
Procedure Training Facility Driving (i.e. Closed Course) Straight line runs with at least 2 hard brake events Multiple Configurations Bobtail Single Pup Twin Pups Record while hitching and releasing pups NTSS 2013 http://tucrrc.utulsa.edu 54
Correlated Data Gathering Simultaneously obtain Tone Ring (VSS) Signals J1939 Network Traffic (e.g. Wheel-based Vehicle Speed) J1708 Network Traffic (e.g. Road Speed) GPS Based Speeds (Vbox 3i and egps-200) Tape Switch on Brake Pedal Brake Chamber Pressures Perform multiple hard braking events Download HVEDR Data NTSS 2013 http://tucrrc.utulsa.edu 55
Instrument Setup NTSS 2013 http://tucrrc.utulsa.edu 56
Instrument Setup (cont.) NTSS 2013 http://tucrrc.utulsa.edu 57
Details on Instrumentation with links: http://tucrrc.utulsa.edu/corellatedddec6dataset.html NTSS 2013 http://tucrrc.utulsa.edu 58
Speed Spikes and Noise Nice signals give predictable and reliable results. Higher speeds Lab Simulated Sine Waves -1 Real Signals may not be nice at low speeds Compromised circuit Drive train rattle Vibration DC with Uniform Noise -1.6 Longer sample times smooth out noise 1 0.8 0.6 0.4 0.2 0-0.2-0.4-0.6-0.8 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 DC with Uniform Noise Sine with Uniform Noise 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0-0.2-0.4-0.6-0.8-1 -1.2-1.4 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 0.06 0.065 0.07 0.075 0.08 0.085 0.09 0.095 NTSS 2013 http://tucrrc.utulsa.edu 59 Time Time Sine 0.1 0.1
Speed Spikes at Shift Points WhBsVehSp(km/h) WheelSpeed(millivolts) speed_raw3d(km/h) 25 20 15 10 5 0 2000 0-2000 -4000-6000 -8000-10000 -12000 25 20 15 10 5 0 edaq-ddec6testingwithhathaway.sie - GPS@speed_raw3d.RN_8 edaq-ddec6testingwithhathaway.sie - ToneRing@WheelSpeed.RN_8 edaq-ddec6testingwithhathaway.sie - OnMotion@WhBsVehSp.RN_8 65 70 75 80 85 Time(secs) External GPS Tone Ring Signal J1939 Speed NTSS 2013 http://tucrrc.utulsa.edu 60
Speed Spikes at Shift Points WhBsVehSp(km/h) WheelSpeed(millivolts) speed_raw3d(km/h) 12.4 12.2 12.0 11.8 11.6 11.4 11.2 11.0 10.8 1000 0-1000 -2000-3000 -4000-5000 17 16 15 14 13 12 11 10 9 edaq-ddec6testingwithhathaway.sie - GPS@speed_raw3d.RN_8 edaq-ddec6testingwithhathaway.sie - ToneRing@WheelSpeed.RN_8 edaq-ddec6testingwithhathaway.sie - OnMotion@WhBsVehSp.RN_8 70.4 70.6 70.8 71.0 Time(secs) External GPS Tone Ring Signal J1939 Speed NTSS 2013 http://tucrrc.utulsa.edu 61
Signal Noise When Slow Some Event Records may show unphysical speed spikes (i.e. 0-55mph in 1 second). The speed sensing circuit automatically increases sensitivity with lower amplitudes More susceptible to noise Can happen with impulses that cause drivetrain rattle NTSS 2013 http://tucrrc.utulsa.edu 62
Tone Ring Noise From Trailer Connection WhBsVehSp(km/h) WheelSpeed(millivolts) speed_raw3d(km/h) 5 4 3 2 1 0 1500 1000 500 0-500 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 edaq-ddec6testing.sie - GPS@speed_raw3d.RN_11 edaq-ddec6testing.sie - ToneRing@WheelSpeed.RN_11 edaq-ddec6testing.sie - OnMotion@WhBsVehSp.RN_11 269.5 270.0 270.5 271.0 271.5 272.0 272.5 Time(secs) External GPS Tone Ring Signal J1939 Speed NTSS 2013 http://tucrrc.utulsa.edu 63
Speed Comparison egps-200 from edaq Vbox 3i GPS J1939 Network Wheel-based Vehicle Speed (Tone Ring) Front Axle Speed (Electronic Brake Controller) J1708 Network Road Speed DDEC Reports NTSS 2013 http://tucrrc.utulsa.edu 64
Speed Records 60 J1939: Wheel-Based Vehicle Speed J1939: Front Axle Speed GPS: VBOX 3i GPS: egps-200 J1708: Road Speed 50 Speed (mph) 40 30 20 10 0 50 100 150 Time(secs) NTSS 2013 http://tucrrc.utulsa.edu 65
Speed Records Hard Brake 60 J1939: Wheel-Based Vehicle Speed J1939: Front Axle Speed GPS: VBOX 3i GPS: egps-200 J1708: Road Speed 50 Speed (mph) 40 30 20 10 0 150 152 154 156 158 Time(secs) NTSS 2013 http://tucrrc.utulsa.edu 66
Zoom on Speed Feature 18 J1939: Wheel-Based Vehicle Speed J1939: Front Axle Speed GPS: VBOX 3i GPS: egps-200 J1708: Road Speed x:155.109 y:7.9873 n:155109 x:155.109 y:15.0739 n:155109 x:155.109 y:14.8695 n:155109 x:155.11 y:14.6489 n:31022 x:155.109 y:10 n:155109 16 Speed (mph) 14 12 10 8 6 155.0 155.2 155.4 155.6 Time(secs) NTSS 2013 http://tucrrc.utulsa.edu 67
Compare Tone Ring Signal to ECM Calculated Speed WheelSpeed(millivolts) RoadSpeed(mph) 6000 5000 4000 3000 2000 1000 0-1000 -2000 20 18 16 14 12 10 8 edaq-ddec6testing.sie - ToneRing@WheelSpeed.RN_2 edaq-ddec6testing.sie - OnMotion@RoadSpeed.RN_2 154.8 155.0 155.2 155.4 155.6 Time(secs) NTSS 2013 http://tucrrc.utulsa.edu 68
Speed (mph) Engine Speed (rpm) DDEC Reports Data DDEC Reports Speed DDEC Reports RPM Hard Brake 60 50 2500 2000 40 30 20 10 1500 1000 500 0-60 -50-40 -30-20 -10 0 10 Time (sec) 0 NTSS 2013 http://tucrrc.utulsa.edu 69
Speed (mph) Engine Speed (rpm) Merge DDEC Data with Network Data 60 50 40 30 20 DDEC Reports Speed Wheel-based Vehcle Speed DDEC Reports RPM J1939 RPM Hard Brake 2500 2000 1500 1000 10 500 0-60 -50-40 -30-20 -10 0 10 Time (sec) 0 NTSS 2013 http://tucrrc.utulsa.edu 70
Speed Data Observations Network speed data are about 0.1 second be hind tone ring signal. GPS units tracked each other around 0.2 mph difference Front Axle Speed over reported speed Likely reduced rolling radius from treadware From the Electronic Brake controller Road Speed (J1708) and Wheel-based Vehicle Speed (J1939) show drops in speed NTSS 2013 http://tucrrc.utulsa.edu 71 Tire slip from braking
Air Pressure Transducer (Front Axle) NTSS 2013 http://tucrrc.utulsa.edu 72
Air Pressure Transducer (Rear Axle) NTSS 2013 http://tucrrc.utulsa.edu 73
Air Pressure for ABS Braking BrakePressLR(PSI) 120 100 80 60 40 20 0 edaq-ddec6testing.sie - OnMotion@BrakePressLR.RN_2 edaq-ddec6testing.sie - OnMotion@BrakePressRR.RN_2 edaq-ddec6testing.sie - OnMotion@BrakePressLF.RN_2 edaq-ddec6testing.sie - OnMotion@BrakePressRF.RN_2 edaq-ddec6testing.sie - OnMotion@FAxSp.RN_2 edaq-ddec6testing.sie - OnMotion@WhBsVehSp.RN_2-20 150 152 154 156 158 Time(secs) NTSS 2013 http://tucrrc.utulsa.edu 74
Left Rear Brake Pressure with Wheel-Based Speed WhBsVehSp(km/h) 100 80 60 40 20 edaq-ddec6testing.sie - OnMotion@WhBsVehSp.RN_2 edaq-ddec6testing.sie - OnMotion@BrakePressLR.RN_2 Increase in pressure causes wheel slip and decrease in measured speed. 0-20 150 152 154 156 158 Time(secs) NTSS 2013 http://tucrrc.utulsa.edu 75
Bobtail Braking Results J1939 brake switch status lags tape switch by 0.07 seconds. 15 psi builds in that time. 40 psi (average operational pressure) lags by 0.25 psi Data show the pressure modulation from the ABS system. Front axle pressures tracked each other. No modulation needed. NTSS 2013 http://tucrrc.utulsa.edu 76
where Determining Drag Factor f = [ (v2 v1) / (t2 t1) ] / g v1 is speed at time t1 v2 is speed at time t2 g is the acceleration due to gravity in the same units of v/t. Example: g = 32.2 ft/s x 3600 sec/hour 5280 ft/mile = 21.95 mph/s NTSS 2013 http://tucrrc.utulsa.edu 77
edaq-ddec6testing.sie - GPS@speed_3d.RN_2 DV Acceleration is the slope 100 80 Dt speed_3d(km/h) 60 40 a = (v2-v1) / (t2 t1) 20 0 145 150 155 160 Time(secs) NTSS 2013 http://tucrrc.utulsa.edu 78
Drag Factor Results Run Description v1 (km/h) v2 (km/h) t1 (sec) t2 (sec) Drag Factor 2a First hard brake - tactor 81.23 2.53 91.895 98.450-0.34 2b Second hard brake - tractor 79.31 7.85 150.935 156.465-0.366 3a Third hard brake - tractor 83.4 5.73 82.485 88.830-0.347 3b Fourth hard brake - tractor 57.32 9.82 147.170 151.170-0.336 5a First hard brake with single trailer 75.19 4.20 244.835 250.310-0.367 5b Second hard brake with single trailer 68.82 3.18 301.950 307.080-0.362 6a Third hard brake with single trailer 71.78 6.01 231.945 236.730-0.389 Adding trailers made the drag factor increase from about 0.35 to 0.42. 6b Fourth hard brake with single trailer 69.13 3.68 311.970 316.760-0.387 9a First hard brake with two trailers 65.18 3.95 96.445 100.630-0.414 9b Second hard brake with two trailers 64.11 2.06 156.090 160.465-0.402 10a Third hard brake with two trailers 63.43 3.92 189.715 193.570-0.437 10b Fourth hard brake with two trailers 61.07 2.44 251.300 255.405-0.404 NTSS 2013 http://tucrrc.utulsa.edu 79
Rear Brake Pressures: Bobtail 120 edaq-ddec6testing.sie - OnMotion@WhBsVehSp.RN_2 edaq-ddec6testing.sie - OnMotion@BrakePressRR.RN_2 edaq-ddec6testing.sie - OnMotion@BrakePressLR.RN_2 100 WhBsVehSp(km/h) 80 60 40 20 0-20 92 94 96 98 100 Time(secs) NTSS 2013 http://tucrrc.utulsa.edu 80
Rear Brake Pressures: Single Pup 120 edaq-ddec6testing.sie - OnMotion@WhBsVehSp.RN_6 edaq-ddec6testing.sie - OnMotion@BrakePressRR.RN_6 edaq-ddec6testing.sie - OnMotion@BrakePressLR.RN_6 100 WhBsVehSp(km/h) 80 60 40 20 0-20 232 233 234 235 236 Time(secs) NTSS 2013 http://tucrrc.utulsa.edu 81
Rear Brake Pressures: Two Pups 100 edaq-ddec6testing.sie - OnMotion@WhBsVehSp.RN_9 edaq-ddec6testing.sie - OnMotion@BrakePressRR.RN_9 edaq-ddec6testing.sie - OnMotion@BrakePressLR.RN_9 80 WhBsVehSp(km/h) 60 40 20 0-20 156 157 158 159 160 161 Time(secs) NTSS 2013 http://tucrrc.utulsa.edu 82
Push Rod Stroke - OK NTSS 2013 http://tucrrc.utulsa.edu 83
Push Rod Stroke - Bad) NTSS 2013 http://tucrrc.utulsa.edu 84
Remove Emergency Brake Line Newer Bolt NTSS 2013 http://tucrrc.utulsa.edu 85
This fell to the ground NTSS 2013 http://tucrrc.utulsa.edu 86
A Dime to Block the Line NTSS 2013 http://tucrrc.utulsa.edu 87
Observations When the dime was removed no pressure would hold when the parking brake was Dime prevented an air leak from a defective chamber Service brake worked to depress the spring to release the brake Pressures were high/normal in the brake line No Pressure modulation since no wheel slip. Push rod stroke was almost double on the defective brake No pushrod stroke when parking brake was set NTSS 2013 http://tucrrc.utulsa.edu 88
Setting a Speed Triggered Event in an ECM A predefined threshold, say 7 mph/s, must be exceeded to trigger an event. If an ECM sees a change in speed of that amount, then a braking event is recorded. Threshold value is found in the Configuration data. NTSS 2013 http://tucrrc.utulsa.edu 89
Fault Codes Fault code data can also be recorded. Faults may occur as part of a crash Example: loss of accelerator pedal signal when a pusher bus or RV runs into a tree. Timing of fault information is not certain yet Fault Freeze Frame Data is often recorded too. NTSS 2013 http://tucrrc.utulsa.edu 90
Freeze Frame Data A list of recorded parameters at the time a diagnostic trouble code was captured. Consists of Suspect Parameter Number (SPN) Fault Mode Indicator (FMI) Occurrence Count Engine Torque Mode Boost Engine Speed Engine Load Engine Coolant Temperature Vehicle Speed Maybe More Manufacturer Specific Data NTSS 2013 http://tucrrc.utulsa.edu 91
Cummins Insite Example NTSS 2013 http://tucrrc.utulsa.edu 92
Failure Mode Indicators 32 possible values describing how a parameter became bad as defined in J1939-73 Uses a Signal Range to divide FMI to severity levels: NTSS 2013 http://tucrrc.utulsa.edu 93
Examples: Failure Mode Indicator FMI=3 - Voltage Above Normal, Or Shorted To High Source FMI=4 - Voltage Below Normal, Or Shorted To Low Source FMI=9 - Abnormal Update Rate FMI=12 - Bad Intelligent Device Or Component Software should interpret these numbers NTSS 2013 http://tucrrc.utulsa.edu 94
Fault Data in Reconstruction Timing of fault data is actively being researched. Freeze frame data may be used as a lower bound Fault data should be tied to physical evidence Gouge in the oil-pan from a wreck corresponds to a loss of oil pressure. Need to use the non-free software to get freeze frame data. NTSS 2013 http://tucrrc.utulsa.edu 95
Historical Data Describes mileage, times, and fuel uses. Attribution is hard (i.e. unknown drivers) There are many counters used in recording historical data. ECM time: Amount the ECM was on Engine time: Amount the Engine was turning Trip data may be different than lifetime data. NTSS 2013 http://tucrrc.utulsa.edu 96
Configuration Data Used to verify speeds from RPM. Shows power settings. Gives governor limits. Shows road speed limits. Configuration data is programmed from the shop or manufacturer. NTSS 2013 http://tucrrc.utulsa.edu 97
Consortium Website All data from crash testing and this presentation will be available at http://tucrrc.utulsa.edu Credentials User: TUCRRCmember Password: TUCRRCpassword NTSS 2013 http://tucrrc.utulsa.edu 98
Safe Travels and Fair Winds. THANK YOU NTSS 2013 http://tucrrc.utulsa.edu 99