The introduction of the Worldwide Harmonized Light Vehicle Test Procedure (WLTP) and Real Driving Emissions (RDE) test requirements for the certification of passenger cars requires mobile emission measurements during real driving cycles in addition to the common emission tests on chassis dynamometer. Due to the randomness of traffic and environmental conditions, it is not possible to repeat a real driving cycle with the same results to investigate issues, for example, the application of engine and transmission control units. This represents a big challenge for the manufacturers research and development departments. It is necessary to know the relevant influences from the real operation of the vehicle in order to reproduce real driving cycles on a test bench. The selection of a adequate validation environment is based on defined target values with which the requirements for accuracy and reproducibility of the test bench can be evaluated. In the classic load simulation of real driving on a chassis dynamometer, the driving resistance coefficients are determined in coastdown tests and then adjusted on the chassis dynamometer. Subsequently, the mapping of the height profile is necessary for the consideration of the track topology. The determination of the elevation profile via barometric altitude pressure or GPS measurement technology respectively map material is very complex in the necessary accuracy. An alternative to this procedure is described by the control modes v-alpha, n-alpha, F-v and F-n. For example, the roll in v-alpha control mode is controlled to a defined vehicle speed, independent of the currently applied traction force. At the same time, the angle of the accelerator pedal alpha of the test object is adjusted to the same speed. Since both control systems follow time-based setpoint values and no driving resistance simulation is running in parallel, the v-alpha control mode does not depend on the knowledge of the driving resistance coefficients. The same applies to the above mentioned control modes. These control modes are particularly suitable for the improvement of data states in which the driving performance remains unaffected, for example for the application of emission behaviour. This paper deals on the necessary extensions for chassis dynamometers as a selected validation environment to be able to use these rule types and classifies them in the IPEK XiL framework. The necessary measured variables for the comparison of the control modes with each other and with the classic load simulation are recorded in a specially constructed test vehicle both in real driving and in test bench operation mode. The results of speed, load and tractive force progression, as well as the energy flow within the vehicle, are then examined with regard to equality, accuracy and reproducibility.
Dipl.-Ing. Sven Cortès, University of Applied Sciences Ulm, GERMANY Prof. Dr.-Ing. Christian Dettmann, University of Applied Sciences Ulm, GERMANY Dr.-Ing. Alexander Heubuch, AIP GmbH & Co. KG, GERMANY Ing. Philipp Boche, University of Applied Sciences Ulm, GERMANY Ing. Niclas Schneider, University of Applied Sciences Ulm, GERMANY