Conti Technology to Give Vehicles a ‘Sixth Sense’

Vehicles, like people, sometimes find it hard to get a grip – but at least our wheeled counterparts have Continental helping them out. The German automotive supplier has entered into partnerships with other firms to develop a new approach to sensor fusion, and Conti says the new system it has come up with can give drivers advance warning about low grip. The system was within the “Friction” project as part of the 6th Framework Programme, co-funded by the European Commission.

At present, when the friction, or grip, between the tyre and the road is compromised, active safety systems such as ABS and ESC can assist. These only react, however, when control of the vehicle is already jeopardised. On other occasions, it is left to the driver to estimate whether a section of road will give enough grip to allow for the vehicle’s current speed. This, as Continental explains, is set to change – based on the data fusion of different sensors, future electronic systems will be able to warn drivers in time when difficult road conditions are approaching.

The new sensor fusion approach uses data from vehicle dynamics sensors and interprets them together with information that comes from additional environmental and tyre sensors. The basic idea is to inform the driver as soon as the limits of friction between tyre and road are close to being reached. For that purpose the system estimates the required friction (friction used) for a particular driving manoeuvre, estimates the maximum available friction (friction potential) and calculates the difference.

Vehicle dynamics sensors

In-vehicle sensors provide the data to estimate the friction between tyres and road. Two strategies are used to estimate friction by calculating the vehicle’s dynamic response. The Continental approach computes, amongst other things, longitudinal and lateral acceleration, wheel speeds, yaw rate and steering wheel angle. Based on a lateral dynamics model, that describes how the vehicle should react under ideal conditions; the actual vehicle reaction indicates the current level of friction. During the sensor fusion development this approach was combined with a second means of friction estimation which is based on steering torque. This alternative strategy was developed by the Centro Ricerche Fiat.

Environmental and tyre sensors

Environmental sensors provide data to the second sub-module which computes the environmental features using the following means: An optical sensor measures changes in the amount of light that is reflected by the road surface directly in front of the front wheel (0.4 to 1.5 metres ahead); a polarisation camera detects differences in vertical and horizontal polarization caused by road surface conditions between 5 and 20 metres in front of the vehicle; finally, a laser scanner checks the weather conditions by detecting objects such as snow flakes or rain drops within a range of 50 to 100 metres ahead of the vehicle. In addition, the road surface temperature is measured by a thermometer and an air thermometer measures the ambient temperature. Yet further information is received via the intelligent tyre sensors, which are integrated into the tyres; these deliver information about the rolling tyre’s current distortion. The system warns against early stages of aquaplaning.

By computing the data from the environmental sensors and checking their plausibility against the thermometer readings, the system can detect the road conditions and thus potential threats to friction. To warn drivers, the complete sensor output and sub-module results are integrated into a tyre-road friction value. This information can warn the driver in time and it can make collision mitigation or collision avoidance systems more efficient under adverse weather conditions.

Displaying the information to the driver

In addition to developing the new sensor fusion approach, Continental has utilised products from its cockpit instrumentation portfolio in order to develop a system that can deliver an ergonomic visual, acoustic and potentially also haptic warning message to the driver. In addition to the cluster instrument, the head-up display can offer ergonomic advantages to communicate the safety critical friction warning.