Continental's Emergency Steer Assist helps drivers when there's no time left for braking
Jun 14, 2010
The system supports obstacle-avoidance maneuvers. Interaction between radar sensors, chassis systems and electric steering. Initial development stage expected to reach production readiness in two to three years.
Frankfurt am Main, Germany. With the development of Emergency Steer Assist, Continental, the international automotive supplier, is pursuing an entirely new approach to accident-prevention driver assistance systems. "Many of the systems in use today are restricted to intervening in the longitudinal dynamics, Emergency Steer Assist is the lateral dynamics complement to Emergency Brake Assist", said Dr. Peter Laier, Vice President of the Chassis Components business unit of the Chassis & Safety Division. "If the driver of a vehicle traveling at high speed has gone beyond the last possible point where braking would have an effect, it may still be possible to avoid an accident through steering, or by taking evasive action. This possibility is not yet being actively incorporated into driving safety." Emergency Steer Assist can now help drivers to steer past an obstacle. It does this by accessing the technologies which are already integrated into many vehicles. The lower the road surface friction coefficient, due to rain or snow for example, the greater the gap between the 'braking' or the 'evasion' options. This means that evasive action is still a possibility long after there is no more hope of avoiding the accident by emergency braking alone.
Sensors help the chassis “to see”
Emergency Steer Assist helps drivers when there´s no time left for breaking.
Before Emergency Steer Assist can be performed, it is essential that the vehicle is fitted with sensors for monitoring the road as far ahead as possible. "The more reliable and detailed a picture of other road users and of the road itself can be gained, the more effectively Emergency Steer Assist can assist the driver to decide, for example, whether to take evasive action by steering to the left or the right when suddenly coming up against the tail of a motorway traffic jam", said Bernd Hartmann, Chassis Systems Advanced Engineering manager in the Chassis & Safety Division. The first stage will employ radar sensors similar to those currently in production for Adaptive Cruise Control (ACC). The advanced engineering department is also working on combining the video images from camera systems, like those already in series production for Intelligent Headlamp Control, with the radar signals. In this way, the chassis will learn to 'see' so that the vehicle's safety systems are given early warning of an imminent hazard situation.
This will place the vehicle in a 'safety mode'. "From this instant, the objective is to avoid an accident; comfort considerations are of secondary importance", said Hartmann. In preparation for the obstacle-avoidance maneuver, the aim is to maximize the vehicle's road-holding ability. In those decisive seconds, the ESC is prepared to keep the vehicle on the road during the rapid avoidance maneuver and to stabilize it by the selective and early application of initial braking pressure to individual wheels. A further conceivable option for the future for vehicles equipped with active roll stabilization or adaptive chassis systems is to adjust the suspension and damper characteristics to the 'hard' mode.
If the driver of a vehicle has gone beyond the last possible point of braking, it may still be possible to avoid an accident through steering, or by taking evasive action. Click here to download this image
Evasive action or emergency stop: the driver always has the last word
The decision as to whether to brake before reaching the obstacle or to steer past it will always remain one for the driver to take. The assistance system will warn the driver that he is about to come across a dangerous situation. The warning could be issued as an acoustical or it could even take the form of a haptical warning signal, the perceptible application of initial braking pressure, for example, or counterforce exerted by Continental's active Accelerator Force Feedback Pedal (AFFP®). If the driver decides to take evasive action, the system calculates in milliseconds what line the optimum evasive maneuver, the so-called vehicle movement trajectory, could follow. Any turn to avoid an obstacle should be carried out with a smooth steering movement so that the vehicle remains stable. By comparing the intended steering angle with the one actually chosen, Emergency Steer Assist determines whether the driver has steered sharply enough or possibly too sharply and can assist him by applying a light force in the steering wheel. "However, in this situation too, the ultimate decision always lies with the driver; if the situation demands it, he can disregard Emergency Steer Assist's offer of help", said Dr. Laier.
Evasive action or emergency stop: the driver always has the last word Click here to download this image
The integration of vehicle systems makes Emergency Steer Assist a possibility
All the systems which are necessary to make Emergency Steer Assist a reality are already installed in series production vehicles. Radar and video sensors work reliably in driver assistance systems. More than 80 percent of all new vehicles registered in Germany are now equipped with Electronic Stability Control (ESC) and this will be made mandatory for all new vehicle models from 2011 and for all new vehicles from the end of 2014. A federal rule will require ESC in all cars, SUVs, pickups, and minivans by the 2012 model year for the US. Under the final rule NHTSA issued in April 2007, 55 percent of 2009 models, 75 percent of 2010 models, 95 percent of 2011 models, and 100 percent of 2012 models must have ESC. There is no government mandate for ESC in large trucks or buses. Electric servo-assisted steering systems are being installed in increasing numbers of vehicles. Actively steered rear axles are also becoming more common. Because the rear wheels are also steered and can support the emergency maneuver, they permit avoidance action to be carried out rapidly and stably. Emergency Steer Assist links together all the useful data from the existing systems. Because the necessary components are already present in many vehicles, manufacturers can implement Emergency Steer Assist relatively inexpensively.
Evasive action or emergency braking
In certain hazardous situations, a precisely executed steering maneuver offers the chance of preventing an accident even if the driver has missed the last moment for deciding to carry out emergency braking. For example, calculations based on simulations show that the distance at which the driver of a typical medium vehicle, driving at 100 kph on a dry road surface needs to initiate an emergency stop to avoid a stationary obstacle is approximately 40 meters. By comparison, evasive action not involving braking can be successfully initiated if the distance from the obstacle is approximately 30 percent less. If the friction coefficient is halved due to a wet road surface, then the last opportunity for taking evasive action is as much as 50 percent of the figure needed to avoid a collision through braking alone. The result is a longer time gap between the 'last point to steer' and 'last point to brake' decision. These calculations are based on the assumption that a complete lane width is available for carrying out the avoidance maneuver as would be required to avoid a stationary obstacle in the middle of the lane.
Braking is the means of choice in inner city areas. Here, because of lower vehicle speeds, an emergency stop is more effective than evasive action. Continental's Emergency Brake Assist City, in series production since two years, prevents collisions at inner city speeds or mitigates the consequences if the driver fails to react.
Emergency Steer Assist is an additional ContiGuard® module
Emergency Steer Assist adds to Continental's portfolio of sophisticated driver assistance systems. These include advanced driver comfort assistance systems which relieve the driver of routine tasks and allow him to react with greater assurance and more concentration even in critical traffic conditions. In contrast, it is precisely in dangerous situations that advanced driver safety assistance systems, such as Emergency Brake Assist, intervene to avoid a rear-end collision for example.
Emergency Steer Assist is an additional module in Continental's ContiGuard® safety concept. This opens up a new dimension of driving safety because ContiGuard® integrates both active and passive safety systems which are more effective and comprehensive due to the utilization of surrounding sensors and their coordinated interaction. By embracing ContiGuard® on the path towards Vision Zero, i.e. road traffic with zero fatalities, vehicle manufacturers can effectively help avoid accidents or at least minimize their consequences and the risk of injuries for all road users.