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.
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.
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.
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| Photo: Continental |
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.