Delphi's Accident Data Recorder 2 (ADR 2) senses and records key vehicle data at 1,000 samples per second prior to, during, and after an accident. The first generation ADR was developed as a way to help improve Formula 1 racing circuit safety and ADR 2 is now used in many major racing series including Formula 1, the Indy Racing League IndyCar Series, CART, Formula 3000, and Infiniti Pro Series.
Since its introduction, the ADR 2 has recorded over 200 racing accidents.
To help determine the forces applied to a driver during an accident, the unit is capable of monitoring 10 external sensors that may be strategically placed throughout the vehicle or on the driver (including in his ears - see below!). The unit also measures the rate of yaw in a moving vehicle, plus throttle position and steering angle, synchronizing data-recording activities with a real-time clock to aid in resolving the events of an accident.
The parameters recorded include:
- Wheel speed
- Throttle position
- Steering angle
- Lap indicator
- X-axis acceleration
- Y-axis acceleration
- Z-axis acceleration
- Yaw rate
- Internal real-time clock
- Auxiliary data from the 10 external inputs
The data is stored in memory to be retrieved later via a high-speed data link to a personal computer. Designed specifically for motorsports applications, the ADR 2 is a highly rugged design. Because of the requirement that it sense all accelerations that occur, the ADR is not able to be mounted on anti-vibration mounts, as are the other car electronic modules. An internal uninterruptible power supply allows operation in the event of vehicle power loss.
The 2MB of RAM allows logging of about 4 minutes, depending on how frequently the data is being logged. This time is usually sufficient to cover two laps, allowing the accident lap to be compared with the previous lap. Logging commences when the engine is running and the unit detects via its accelerometers that the car is in motion.
The data derived from the ADRs used in Formula 1 cars is used within the FIA's Circuit Safety Analysis System to determine the required extent of run-off areas and barrier specifications. For example, the maximum deceleration achieved by cars in gravel traps and on wet and dry on-track surfaces has been extensively assessed.
The crash data from the ADR is also used to model a Severity Index Coefficient, a number used to evaluate the likely magnitude of driver injury in a variety of crashes.
Writing in a Society of Automotive Engineers paper, the FIA's Peter Wright says that the data acquired from Formula 1 Accident Data Recorders "has been beneficial in assessing the performance and developing safety features, car impact structures and barriers, and in assisting in modelling and reconstructing impacts to understand their dynamics and injury-causing mechanisms".
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Accident Data Recorder 2 Technical Statistics
- Dimensions: 135 mm x 116 mm x 53 mm
- Voltage range: 6.5 to 20 Volts
- Temperature rating: Up to 70 degrees Celsius
- Microprocessor: 32 bit, 25 MHz
- Program memory 512kB Flash EPROM
- 4 serial data links:
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- RS 232, 9600 baud
- RS 422, 115 kbaud
- RS 422, 921 kbaud
- CAN, 1 Mbit
- Internal sensor set:
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- (3) 500 g accelerometers
- (3) 50 g accelerometers
- (1) 200 degree per second angular rate sensor
- High g accelerometer resolution: 0.25g (12 bit)
- Low g accelerometer resolution: 0.025 g (12 bit)
- Angular rate sensor resolution: 0.1 degrees per second (12 bit)
- Case: Aluminium 6061-T651, Anodized black per MIL-A-8625
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Earpiece Sensor System
The newly developed Delphi Earpiece Sensor System uses small sensors integrated into the left and right radio earpieces worn by the driver. The six accelerometers - one for each of the three axes on each side - measure head acceleration in the X, Y, and Z axes during an accident. The combined data from the earpiece sensor system and onboard accident data recorder provide accident researchers valuable data for a clearer picture of what happens during an accident.
The system is required equipment for the 2003 racing season for all Indy Racing League (IRL) IndyCar Series and Infiniti Pro Series drivers. The system was introduced and tested with Scott Sharp and the Kelley Racing team in 2002.
Data measured by the sensors is stored in Delphi's ADR 2.
The combined data from the earpiece sensors and vehicle operation measurements will help give safety researchers and the IRL a clearer picture of what happens during an accident.
"Safety is our number one priority," said Dr Henry Bock, medical director for the Indy Racing League. "We believe this research project will play an important role in helping to quickly bring an even higher level of safety to racing."
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Delphi Earpiece Sensor System Technical Statistics
- Dimensions: 9.9 mm x 10.2 mm x 6.6 mm
- Temperature range: -0°C to +70°C
- Output voltage range: 0-5.0 volts
- Measurement range: ±250 g
- Filtering: 400 Hz, 2 pole Bessel filter
- Pre-filter headroom: ±400 g
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Safety Light
Working closely with Dr Henry Bock, Delphi has also developed a simple system for measuring and communicating the impact of a crash to rescue and safety workers on the scene.
The device is a visible red light mounted on the outside of the car. It is controlled by the ADR 2. The light illuminates when a crash reaches or exceeds a pre-set threshold, telling doctors and paramedics that injury is more likely.
"Based on years of industry research on crash and accident data, we already know that if a driver experiences a certain amount of force, the likelihood for injury, such as head trauma, increases significantly," said Dr Bock. "Knowing that a crash has exceeded a threshold, safety workers on the scene will adjust their mindset - anticipating that injury has occurred and tailoring their assessment and extrication plans to properly support the driver."
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Passenger Cars?
In addition to racecars having their own on-board crash data logging system, some passenger cars also have a similar system integrated into their airbag control computers.
GM cars sold in the US, for example, log four pre-crash parameters (speed, revs, throttle opening and brake pedal on/off) and five crash parameters (including change in forward speed, airbag warning light status and the time it took the airbag to fire).
Other manufacturers are also incorporating some forms of logging into their airbag systems. If you are involved in a major crash which involves late model cars - and there is any uncertainty as to what happened - it's worth checking with the car's manufacturer whether this data can be retrieved.
Julian Edgar
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