Black box recorders are widely used by insurance companies and road accident investigators to assess major car crashes. However, the technology has not been able to accurately determine what has occurred in low-level crashes – until now. Wayne Gilbert, CTO, Risk Technology, explains.
When vehicles are involved in a serious crash, there is little doubt that the event has occurred as sizeable, easily measurable g-forces are generated by the impact. The vehicles stop, names and addresses are exchanged, and an insurance claim usually results.
However, this is only the tip of a cost iceberg as far as insurers are concerned. Many accidents do not involve bent metal or personal injury, which is how a serious car crash is defined. Dents and scrapes also lead to costly claims. Also, insurers are exposed to unkown costs due to delays in claims.
The problem is that detecting low-level crashes is difficult. Forces created by bad driving (curbing a front wheel at the approach to a roundabout) or bad road surfaces (potholes) can create forces similar to a minor crash. And neither owners nor insurers wish to be troubled with false alerts to incidents.
So the technologist is stuck with a problem – set the g-force thresholds to a low-level and deal with annoying false reports or set the limits higher but miss some crashes.
Advanced Crash Detection (ACD) technology now exists that operates by using two independent methods for detecting impacts.
The first method detects g-forces acting on the vehicle in three axes x y and z. This is accomplished with an accelerometer array. The second method detects acoustic waves transmitted through the body of the vehicle.
A collision is indicated only when the thresholds of both the acoustic and g-forces are met.
(Conventional methods use only the accelerometer technology, which creates a problem in discriminating between environmental factors, such as speed bumps, potholing and curbing, and low-speed impacts.)
How it works
Few drivers will be unaware of the noise created when the plastic materials at the front or rear of a car are hit by a supermarket trolley. In this example, the energy transmitted is low and very little g-force will be seen by the detection system. But the familiar sound is also transmitted through the structure of the vehicle and detected by a sensor, with the possible conclusion that some paint has been scraped.
The trigger thresholds for both g-forces and acoustic input are configured by software and may be different for larger and smaller vehicles and may be actively learned by the devices. These include measures of both the strength of the impact and its duration.
Critically, acoustic sensing detects structure-borne waves, not sound from the impact (although the two events do occur simultaneously). Therefore, loud music or the kids fighting in the back seat will not trigger the sensing system.
Extensive testing of the technology has already taken place, using calibrated sensors and a controlled environment (Sled Tests). Pre-production devices fitted with the technology have also been tested extensively in road trials.
The program took a number of devices and fitted them into test vehicles in a controlled environment. Test vehicles were then be exposed to a range of test collisions at low speeds (simulating the worst-case situation) to evaluate the behavior of the devices and to ensure that detection of the events occurs.
Test vehicles were also fitted with laboratory instruments and cameras to record all the tests in detail. The data output from the devices was sent wirelessly to servers to ensure end-to-end functionality.
The results showed excellent consistency and rejection of false positives.
Only the beginning
Further work is being carried out to use data extracted from the vehicle itself. For example, were the brakes applied at the time of the incident? What was the throttle position before the event? Were the seat belts fastened? But that is only the beginning.
As a next step, the technology will include data about the road conditions – weather, traffic density and local accident records will be included. Not only will such information help insurers and car investigators understand the actions of the driver, but it will also help them understand any environmental factors, thus increasing the accuracy of the data and avoiding possible misinterpretation.
Wayne Gilbert is CTO at Risk Technology.
For all the latest telematics trends, check out Consumer Telematics Show 2014 on Jan. 6 in Las Vegas, Telematics for Fleet Management Europe 2014 on March 12-13 in Amsterdam, The Netherlands, Content and Apps for Automotive Europe 2014 on April 8-9 in Munich, Germany, Telematics Detroit 2014 on June 4-5 in Novi, Michigan, and V2X and Auto Safety USA 2014 on July 8-9 in Novi, Michigan.
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