Vehicular Forensics
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We use the BOSCH Crash Data Retrieval System to download the Airbag System Sensing and Diagnostic Module. “CDR” is the acronym for Crash Data Retrieval used to describe the CDR Tool and “EDR” is the acronym for Event Data Recorder which is a function of the airbag control module (ACM). The CDR Tool is a commercially available system comprised of hardware and software that is currently used by law enforcement, collision reconstructionists, fleet managers and government researchers to access and “image” EDR data which may be stored in control modules found in passenger cars, light trucks and SUVs.
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The airbag control module's potential capability to save data after a crash has caused some to mistakenly refer to it as an "event data recorder” or EDR and moreover the “black box”. In reality, the airbag control module's primary job is to detect sudden changes in direction and/or rotation and, when appropriate, deploy restraint devices like airbags. The ACM uses certain bits of information including that from crash sensing systems, seat belt related sensors and occupant detection systems to decide whether or not and when to deploy airbags and other restraint system devices. When certain conditions are met, the airbag control module may record data associated with these sudden changes in direction and/or rotation (i.e. a crash) which can later be “imaged” by the CDR Tool.
Different make and model vehicles record different amounts of data and a different number of “events”. An “event” is a crash or other physical occurrence which causes a trigger threshold to be met or exceeded. Data from the collision is stored in the airbag control module as either a “non-deployment” event or a “deployment” event. You should ALWAYS image a supported vehicle even if the impact was so minor that an event was not recorded.
A non-deployment event is a sudden change in direction and/or rotation of the vehicle that “wakes-up” or “enables” the ACM but makes a decision not to deploy any of the safety restraints; for example, hard braking. On the other hand, you could have a deployment event. A deployment event is a sudden change in direction and/or rotation that “wakes up” or “enables” the ACM and is sufficient to warrant a command deployment.
Some of the key data parameters that are recorded in the ACM are listed below and certain ACM types include up to 5 seconds (or more) of pre-crash data. With the CDR Tool you now have access to a physical, non-biased, representation of what the vehicle was doing 5 seconds prior to impact (typically recorded in 1 second intervals).
Different make and model vehicles record different amounts of data and a different number of “events”. An “event” is a crash or other physical occurrence which causes a trigger threshold to be met or exceeded. Data from the collision is stored in the airbag control module as either a “non-deployment” event or a “deployment” event. You should ALWAYS image a supported vehicle even if the impact was so minor that an event was not recorded.
A non-deployment event is a sudden change in direction and/or rotation of the vehicle that “wakes-up” or “enables” the ACM but makes a decision not to deploy any of the safety restraints; for example, hard braking. On the other hand, you could have a deployment event. A deployment event is a sudden change in direction and/or rotation that “wakes up” or “enables” the ACM and is sufficient to warrant a command deployment.
Some of the key data parameters that are recorded in the ACM are listed below and certain ACM types include up to 5 seconds (or more) of pre-crash data. With the CDR Tool you now have access to a physical, non-biased, representation of what the vehicle was doing 5 seconds prior to impact (typically recorded in 1 second intervals).
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Also, available for use in vehicle testing is the Vericom VC4000DAQ Dynamometer and Braking Test Computer . It operates in two modes; braking and accelerating. The two most common uses in the braking mode are determining the coefficient of friction of the road surface, and analyzing the vehicle's braking ability. The common uses for theVC4000 in the acceleration mode are determining acceleration rates and times. The system is capable of analyzing a variety of input sources. These include lateral acceleration, reaction time, brake system pressures, brake pedal force application, and analysis of the vehicle electronic operational systems via the Diagnostic Link Connector (DLC - OBD II).
We also have available the Stalker Acceleration Testing System (STATS). This RADAR based system provides a detailed picture of the dynamics of acceleration, braking, or kinetic testing. The Stalker ATS software program displays the test results in various graphical forms and calculates exact performance statistics. The computer records the speed data, assigns time information, and calculates distance and acceleration rates for each data sample. The measurements are typically within 1/100th of a second.
Find all of the Crash Data Group videos: Crash Data Group YouTube Channel