AAA research reveals that heavy rain often defeats ADAS functions

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The American Automobile Association (AAA) has released the findings of an independent research project that assessed the impact of adverse weather on ADAS performance. The results show that in less than perfect weather conditions, the effectiveness of such systems is considerably reduced.

During closed-course testing using simulated moderate to heavy rainfall, emergency brake system tests using a variety of vehicles resulted in collisions occurring 17% of the time at 25mph (40km/h) and 33% at 35mph (56km/h). Of greater concern are the findings from the lane-assist system tests, in which vehicles veered from their lanes 69% of the time.

To simulate rainfall, AAA engineers designed a vehicle-mounted system using a reservoir to hold water, a high-pressure pump for a consistent flow of water and a precision injector nozzle to spray the windshield. This system was secured in the cargo area of the test vehicle and connected to a nozzle positioned above the windshield so that the spray pattern covered the entire windshield. Water sprayed by this system did not reach the pavement or interact with the test vehicle’s tires.

More encouraging are the results from tests looking at the effect of a dirty windshield, in which vehicles’ screens were stamped with a controlled mixture of bugs, dirt and water. AAA reports that the overall system performance was not affected.

“Vehicle safety systems rely on sensors and cameras to see road markings, other cars, pedestrians and roadway obstacles. So naturally, they are more vulnerable to environmental factors like rain,” concluded Greg Brannon, AAA’s director of automotive engineering and industry relations. “The reality is people aren’t always driving around in perfect, sunny weather so we must expand testing and take into consideration things people actually contend with in their day-to-day driving.”

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Lawrence has been covering engineering subjects – with a focus on motorsport technology – since 2007 and has edited and contributed to a variety of international titles. Currently, he oversees Automotive Powertrain Technology International and Professional Motorsport World magazines as editor.

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