Objectified Drivability Evaluation and Classification of Passenger Vehicles in Automated longitudinal Vehicle Drive Maneuvers with Engine Load Changes 2019-01-1286
The increasing number of passenger car derivatives in all global markets due to regional different legislative requirements (e.g. RDE in Europe), different market specific driver behaviors as well as demands and the vehicle manufacturers’ efforts to achieve brand specific drivability characteristics as unique selling propositions, require an objectified evaluation and classification approach for the drivability capabilities of a car. For this, it is necessary to evaluate the influence of different engine concepts in various complex and interlinked powertrain topologies during engine load change maneuvers based on physical criteria. Such an objectification approach enables frontloading of drivability related engineering tasks and even allows to starting drivability calibration tasks already in early component conception phases of a new vehicle or a vehicle derivate development program. It can be adapted to various closed-loop co-simulation scenarios (e.g. Hardware-in-the-Loop or Engine-in-the-Loop), where the appropriated response of non-available hardware components is achieved by highly accurate real-time models interacting with the vehicle subcomponents physically available on a test bench (e.g. the combustion engine). The resulting compaction and parallelization of the calibration work to meet the emissions, OBD as well as drivability requirements reduces the development costs and time drastically as drivability functionalities so far were calibrated only towards the end of a development program, when test vehicles with a higher level of product maturity became available.
This article presents an objectified drivability evaluation and classification approach for passenger cars, which is based on physical criteria, developed by RWTH Aachen University in cooperation with FEV Europe GmbH. Initially, the challenges for the passenger vehicle drivability calibration and essentially relevant powertrain drivability functionalities are explained. Based on this, the derived physical criteria for the objectification of longitudinal drivability load change maneuvers results are presented and their subjective significance is explained. The calculation and variation of these criteria are discussed before the background of reproducibility and vehicle-spanning sensitivity. Hereby, both, the automated method for determining and recording of the drivability measurements as well as the results of sensitivity tests, which are based on calibration changes with regard to the longitudinal vehicle drivability behavior, are explained in detail. Individual disturbances and their influence on the results and physical criteria are also discussed. Finally, by presenting and discussing the results of a multitude of driving tests with a multitude of vehicles using different characteristic diagrams (e.g. scatter bands), the reliability, maturity and validity of the method are presented.
Daniel Guse, Christian Heusch, Stefan Pischinger, Stefan Tegelkamp, Christopher Schmidt, Henning Roehrich, Martin Nijs, Johannes Scharf
RWTH Aachen University, FEV Europe GmbH