Every driver is familiar with this unpleasant feeling: the moment when the car begins to glide on a wet road surface and no longer responds reliably to steering commands. And it makes no difference whether such aquaplaning catches a good or bad driver.
So for this reason, together with Porsche, we have developed the "wetness detection" function. This innovational technology is now going into series production in the Porsche 911 and is thus supporting the world premiere of the "Porsche WET mode". This application has enabled the German car manufacturer to develop a new assistance function, which is designed to make driving even safer.
Thanks to this new kind of sensor, the vehicle is able to recognise distinct wetness on the road surface. A preventive measure is triggered to regulate the driving systems which then aim at more stable driving behaviour. In this way it is hoped to detect the gliding of a vehicle in wet conditions at an early stage and ideally to prevent any critical situations from arising.
An essential component of the innovational system is the SHAKE structure-borne sound sensor (short for Structural Health and Knock Emission) developed by HELLA. Installed in the front wheel arch liners of the Porsche 911, the sensor recognises the road condition and detects the film of water on the road surface. By means of a piezoelectric element, the SHAKE sensor detects vibrations and airborne noise from water droplets swirled up in the air and from this information determines the degree of wetness between the tyres and the road.
"This is a great advantage over most of the systems available to date, which only warn when a critical driving situation with a very wet road surface has already occurred," explains Michael Jaeger, who, as a member of the HELLA Electronics Management Board, is responsible for actuators and sensor systems.
The wetness sensor also offers great potential when it comes to autonomous driving. "Because in order to be able to determine static friction and thus braking distances, precise information about road conditions is vital. This is exactly what the SHAKE sensor can reliably detect," boasts a convinced Jaeger. Small sensor, huge potential.