Jacek Toczyski University of Virginia SAE Government ... · XYZ Global . Algorithm. Position •...
Transcript of Jacek Toczyski University of Virginia SAE Government ... · XYZ Global . Algorithm. Position •...
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Dummy head motion tracking in
crash tests with standard sensors
SAE Government Industry MeetingJanuary 24-26, 2018
Jacek ToczyskiUniversity of Virginia
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Motivation
NHTSA’s oblique crash test On-board view
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Overall Study Goals
• Prepare a software package that calculates head trajectory in a global reference frame from onboard sensors
• Application: THOR ATD in Oblique– Other applications: other tests, other body regions
• Additionally:– Evaluate potential and magnitude of error in calculated 3D
trajectory from test procedure and sensor related errors
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Project flow chart
Algorithm Coding Error Effects
modeling
Simplified Head Testing
Modified Code
FE/MB Validation
SimulationsUser Interface
Modified Code
Development
THOR ATD Tests
Modified Code + Modified
Instrumentation Plan
Final Software
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Algorithm coding (backend code)INPUT:
XYZ Local XYZ Local Acceleration Angular Rate
OUTPUT:XYZ Global
PositionAlgorithm
• Step 1: Translating acceleration from sensors to point of interest• Step 2: Time History of Local/Global Transformation (7 methods
identified)• Step 3: Transformation of local acceleration to global frame and
double integration
Local Frame Orientation
Sensor Locations
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Project flow chart
Algorithm Coding Error Effects
modeling
Simplified Head Testing
Modified Code
FE/MB Validation
Simulations
Modified Code
User Interface Development
THOR ATD Tests
Modified Code + Modified
Instrumentation Plan
Final Software
![Page 7: Jacek Toczyski University of Virginia SAE Government ... · XYZ Global . Algorithm. Position • Step 1: Translating acceleration from sensors to point of interest • Step 2: Time](https://reader036.fdocuments.in/reader036/viewer/2022071017/5fd14ed9586af90d4e0ec489/html5/thumbnails/7.jpg)
Validation Simulations
Sled test
OMDB-to-vehicle
MB simulation
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Validation Simulations
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LS-Dyna
Kerrigan
Error
Algorithm coded
correctly
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Project flow chart
Algorithm Coding Error Effects
modeling
Simplified Head Testing
Modified Code
FE/MB Validation
Simulations
Modified Code
User Interface Development
THOR ATD Tests
Modified Code + Modified
Instrumentation Plan
Final Software
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Simplified Head Testing
Multiple sensors including ARS & linear and angular ACC
VICON data used as Reference
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Flat, 0 deg Wedge, at 45 deg
Simplified Head Testing
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Error:Absolute Error (Vicon-Calculated)
Simplified Head Testing
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Project flow chart
Algorithm Coding Error Effects
modeling
Simplified Head Testing
Modified Code
FE/MB Validation
Simulations
Modified Code
User Interface Development
THOR ATD Tests
Modified Code + Modified
Instrumentation Plan
Final Software
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THOR ATD tests
Simplified Head; 2kN FL
8 tests in total
Regular Head; 4kN FL; impactRegular Head; 4kN FL
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THOR ATD tests
8 tests in total
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Error:Absolute Error (Vicon-Calculated)
Head Impact at 116-120 ms
THOR ATD tests
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Project flow chart
Algorithm Coding Error Effects
modeling
Simplified Head Testing
Modified Code
FE/MB Validation
Simulations
Modified Code
User Interface Development
THOR ATD Tests
Modified Code + Modified
Instrumentation Plan
Final Software
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Error Effects Modeling
Errors considered:• Initial orientation• Initial position• Noise level• Sensitivity error (multiplicative error)• Debias error (offset error)
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• Bounds identified• Each error:
– 15 values within the bounds– Spaced equally (assuming 15 values)
• Implemented one at a time (univariable analysis)• Compared to baseline (assumed "ideal")
response
Error Effects Modeling
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Error hierarchy Error type Max difference after 250ms (mm)1. ACC Debias 750 (for debias error of 2g)2. ARS Debias 210 (for debias error of 50deg/s)3. ACC sensitivity 50 (for sensitivity error of 4%)4. Orient 30 (for Yaw error of 1deg)5. ACC Noise 17 (for noise scaled up)6. ARS Noise 6.6 (for noise scaled up)7. ARS sensitivity 6.4 (for sensitivity error of 1%)8. ACC CG location 4.5 (for ACC CG location error of 1mm)9. Head CG initial location 2.5 (for ACC CG location error of 2.5mm)
Error Effects Modeling
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Error Effects Modeling
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Project flow chart
Algorithm Coding Error Effects
modeling
Simplified Head Testing
Modified Code
FE/MB Validation
Simulations
Modified Code
User Interface Development
THOR ATD Tests
Modified Code + Modified
Instrumentation Plan
Final Software
![Page 23: Jacek Toczyski University of Virginia SAE Government ... · XYZ Global . Algorithm. Position • Step 1: Translating acceleration from sensors to point of interest • Step 2: Time](https://reader036.fdocuments.in/reader036/viewer/2022071017/5fd14ed9586af90d4e0ec489/html5/thumbnails/23.jpg)
Final software
INPUT:OUTPUT:
XYZ Global PositionAlgorithm
Graphical User Interface Backend code(MATLAB
based)
*.xlsx files(Acc, Vel,
Pos, Check, Orientation)
Local FrameOrientation
XYZ Local Acceleration
XYZ Local Angular Rate
Sensor Locations
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Graphical User Interface
First screen Last screen
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DUMMY HEAD MOTION TRACKING IN CRASH TESTS WITH STANDARD SENSORS
Thank you for your attention
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Error type:Yaw, 1 deg off from initial
Error metric:RMS X = 12.8 mmRMS Mean = 4.3 mm