F2008-12-014
Customer Oriented Safety and Handling Evaluation via Adjusted Driver Model Using Real Vehicle
When trying to optimise the lateral vehicle dynamics car manufacturers always have to balance the two competitive objectives safety and agile handling. Safety stands for an easy controllable vehicle even in difficult driving situations. Good handling qualities are given by a high performance vehicle and lead to driving pleasure. To reach the next step in lateral vehicle evaluation it is essential to reproduce the customerīs driving behaviour.
Up to now in the automobile industry lateral vehicle dynamics is improved and developed by expert drivers, whose driving behaviour and evaluation are often completely different from an average driver representing most customers. Due to this conflict a new approach in vehicle testing is made. Two driver models representing an average driver and a sportive driver are used in combination with a steering robot in a real vehicle to gain objective feedback on a carīs lateral dynamics. In contrast to the human driver, who will adapt his style of driving to a given car and manoeuvre in order to compensate for a carīs characteristics at the stability limit, the driver modelīs behaviour does not differ. Therefore driving manoeuvres can be repeated reproducibly with a constant driver influence up to the vehiclesī limit.
In order to determine the parameters needed for realistic driver models the driving behaviour of average test persons during road test is recorded. With known vehicle characteristics derived from open loop tests and assuming that the combined vehicle driver behaviour remains constant the subsequent data analysis yields the dynamic response of each person. This data is then used to tune the two driver models.
Further the choice of the manoeuvre depends on whether to evaluate safety or handling. Obstacle avoidance manoeuvres are convenient to analyse the lateral road holding ability. In combination with the average driver model it is now possible to reproduce a difficult driving situation under realistic conditions. For investigating the handling performance of a vehicle circuits with high lateral forces comparable to country roads are a lifelike basis. These tracks are combined with the sportive driver model allowing to analyse the handling of the vehicle.
These two approaches are tested in different ways. To analyse safety a steering robot which can be mounted in nearly any passenger car is used. For investigating handling a production car with EPS and electronic pedals named GTI 53+1 was build up. Both setups use a dGPS based inertial measurement unit with a position accuracy of up to 2 cm. In consequence with this method it is possible to get reproducible measurements with a validated and constant driver influence at the stability limit oriented at the different goals of the customer concerning vehicle safety or driving fun.
Session: Ride & Handling