With its Road Condition Observer, Continental has introduced a solution that allows road conditions to be classified with regard to tyre/road friction.
The system under development is all encompassing – tyres, tyre-sensors, cameras, algorithms, brake actuation, and the human-machine interface.
Predictive aquaplaning risk recognition
Continental’s developers are focused on predicting and managing the risk of aquaplaning. The objective is to detect a possible front-wheels floating situation as early as possible in order to trigger an early warning to the driver.
Utilising signals from surround view cameras and tyre-mounted eTIS (electronic-Tyre Information System) sensors, an early warning concerning the approaching aquaplaning situation is provided to the driver. Continental is also working on the control and stabilisation of vehicles in aquaplaning situations, such as torque vectoring by individual wheel braking.
Detecting an imminent loss of control through sensor re-use
To detect aquaplaning situations, video images from surround view cameras mounted in the side mirrors, the grill, and rear are analysed. “When there is a lot of water on the road, the camera images show a specific splash and spray pattern from the tyres that can be detected as aquaplaning in its early phase”, said Bernd Hartmann, head of Enhanced ADAS (Advanced Driver Assistance Systems) & Tyre Interactions within the Advanced Technology department of Continental’s Chassis & Safety division.
For example, excessive water displacement in all directions underneath the tyre is a characteristic attribute. During the first testing phase of the new solution, the wetness recognition algorithms delivered a very high hit ratio in predicting potential aquaplaning conditions.
In addition to image information, Continental uses information from tyres to detect the risk of aquaplaning. In this concept, signals from Continental’s eTIS sensors, mounted on the tyre’s inner liner, are computed. “We use the accelerometer signal from the electronic-Tyre Information System to look for a specific signal pattern”, said Andreas Wolf, head of Continental’s Body & Security business unit.
A tyre model processes the incoming radial acceleration of the part of the tyre that is in contact with the road. For wet roads – when enough water is transported out of the tyre tread to ensure an appropriate grip – the signal shows a distinct pattern.
As soon as a wedge of water begins to form in front of the tyre footprint region and there is excessive water on the road, the acceleration signal begins to oscillate in a characteristic way, indicating an early risk of aquaplaning. Since the eTIS sensors can also detect the remaining tyre tread depth, a safe speed for a given wet road condition can be calculated and communicated to the driver.
Testing has shown that future aquaplaning assistance will also have the potential to intervene in an actual aquaplaning situation by applying the rear brakes in a controlled way to establish a degree of “torque vectoring” in order to maintain vehicle manoeuvrability within physical limits.
Contribution to Vision Zero
Not only is aquaplaning a challenge to the driver, but it is also difficult to pin down how many country road and highway accidents in wet road conditions are caused by floating front wheels. “This is one of the last white spots on the strategic map towards greater road safety”, said Bernd Hartmann.