CISS Crash Impact Sound Sensing Crash Detection Performance Improvements at lower cost Dipl.-Ing. Michael Feser University of applied science Ingolstadt
CISS Crash Impact Sound Sensing Crash Detection Performance Improvements at lower cost Motivation Technology Benefits Test Results
Overview Occupant Sensing OOP Sensing Pre Crash Sensing Vehicle Dynamics Sensing PPS Sensing ECS Sensing Pressure Sensing Crash Impact Sound (CISS) X,Y,Z Acceleration Sensing Roll Rate Sensing GPS Pre-Crash System Reversible Actuators Crash Situation Impact Velocity Time to Impact Restraint System Analog Crash Severity Algorithm And Restraint Activation Restraint System Door Unlock Crash Data Recording Care Safe Pre Crash Active Safety Passive Safety Crash Post Crash Individualized restraint systems need more and earlier crash information
High Performance Standard Performance C I S S Faster Fire Times Higher Robustnes Less Cost Crash Impact Sound Sensing SiemensVDO Distributed Sensing Mechanical Sensors Occupant Detection Individualized Restraints 1980 Pressure Sensing for Side Impacts 2004 today Single Point Sensing Electronic Sensors Single Point Sensing Side Satellites Distributed Sensing (ECS) Electronic Sensors Performance Increase Speed, New Modes Crash Impact Sound Sensing (CISS) Crash Sensing Today and Market Trends 1990 1995 1998 Combined p/g sensing 2008 Combined g/ciss sensing Distributed Sensing for Side (p/g-based) 2002
Motivation Wall 0 AZT Angular ODB Pole Frontal Crash Situations and Challenges 0-10 64 kph ODB 40% left 21 kph 0 Wall 15 kph AZT 40% left ECU ODB AZT Wall -30 0 5 10 15 20 25 30 35 40 Time [ms] vs. velocity reduction [kph] AZT 0-10 ECS struck side Wall ODB -30 0 5 10 15 20 25 30 35 40 0 AZT -10 ECS non struck side ODB Wall -30 0 5 10 15 20 25 30 35 40
Motivation Acceleration [g] 5 0 Challenge: Front - ODB Discrimination -5 AZT 16 kph -10-15 BP Stage 1 Stage 2 Time in ms 0 5 10 15 20 25 30 35 40 45 50 ODB 64 kph Discrimination within required fire time physically not possible
Motivation Applications at the Limit have a Performance/Robustness Dilemma Possibility 2: Increased Robustness CISS today's technology Possibility 1: Increased Performance Performance (Firing Time) today's technology Robustness (Quality of the decision) ISS solves the dilemma
Motivation Wall 0 AZT Angular ODB Pole Frontal Crash Situationen CISS Technology 64 kph ODB 40% left 21 kph 0 Wall 15 kph AZT 40% left 250 ECS struck side 14 ECU 0 5 10 15 20 25 30 35 40 250 ECS non struck side 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 Time [ms] vs. CISS Signal [g]
Physical Principles CISS signals provide additional information to distinguish the severity of a crash Today's accelerometers are sensing the displacement Structural sound is looking for the deformation rate High deformation rates are stimulating sound waves at high frequencies The sound waves are traveling through the structure to the sensing element CISS signals have a 50 times higher frequency range than accelerometers The CISS sensor provides both Information out of one sensing component
Physical Priciple Testing of a low carbon steel tensile specimen Drop Test with Frame Impact Sound, Counts/s Source: Impact Sound Plastic Region Elastic Region Stress Strain, in./in. Acoustic Emission During orthogonal Metal Cutting, D.A. Dornfeld and E. Kannatey-Asibu Sensor Element Folds Bending Wave Quasi- Longitudinal Wave 1st Fold 2nd Fold 3rd Fold c B =2 400 Hz 50 khz 2π f h c 12 L m c B 106 s m c B 2400 s c L = E ρ (1 µ c L 5.200 m s Steel Plate thickness 3mm 2 ) Droptest 1,8m
Physical Priciple 0 ms 15 ms 20 ms 25 ms ODB AZT
Micro machined Sensor Principle TETHER PROOF MASS (BEAM) ACCELERATION FIXED OUTER PLATES ANCHOR C1 < C2 SENSOR AT REST RESPONSE TO APPLIED ACCELERATION (MOVEMENT IS GREATLY EXAGGERATED)
Crash Impact Sound Sensing (CISS) Applications and use cases Front v Side Faster firing times for critical crash situations (angular, ODB) Excellent discrimination robustness for critical crash situations Fast firing of belt pretensioners Fast safing function for critical crash situations (IIHS) Excellent firing times in combination with pressure side sensor Rear v v Fast safing with different physical principle System CISS is an extension of the classic sensing technology Increased flexibility for sensor system and packaging Reduced number of sensors leads to cost reduction
Benefits - Summary Excellent Robustness for discrimination of critical load cases Earlier Firing Time especially for ODB and angular situations No compromises in calibration CISS sensor Fast safing/plausibility for side and rear crash situations Scalable Sensor Architecture optimized for different markets and vehicles ACU integrated Less sensors lower cost C I S S The way back again to single point sensing
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