Abstract
As shown in paper F2010-C-177 [1] and the presented X-in-the-Loop-approach, the understanding of the systems “vehicle”, “environment” and “driver” and their interactions are essential for the development and testing of new vehicles, components, driver assistance systems etc. When performing tests e.g. on the chassis dyno, the system design changes and thus the system behaviour and interfaces. The objective of this study is the identification and investigation of all the relevant influences on measurement tasks such as vehicle acoustics, performance, drivability, certification etc. which can vary between tests on the road and on the test bed. In each phase of the product/vehicle development process different measurement tasks have to be processed. The trend is towards relocating measurements to earlier development phases, which means more tests have to be carried out on the test bed. Depending on the measurement task and the system under development layer, different physical and virtual subsystems and/or interfaces are necessary. The main systems are the “vehicle”, including the rest vehicle model, the “driver” and the “environment”. Interfaces are required between all these systems to allow the transfer of energy, material and information. For example an important interface for exterior acoustic measurements is the tire-road working surface pair, where propulsion energy and position information is exchanged. The contact changes dramatically when being transferred from the road to the test bed, which influences e.g. the sound pressure level and therefore the A-weighting. This study is focused on vehicle measurement tasks that are normally performed on the road or test track and can be transferred to the chassis dyno. These tasks and their system design are described methodically using the X-in-the-Loop (XiL) approach [1]. The investigation is limited to the most important influences on a common measurement task on the chassis dyno. The evaluation of the influences is discussed mostly in qualitative terms but gives a good overview. Using the XiL approach, a holistic description of the measurement tasks/use cases and the influencing quantities is now possible. Especially the influences of the vehicle fixation on the chassis dyno are often overlooked while its impact on many measurements is serious. Furthermore the study can be used as a guideline in testing on the chassis dyno where the most important interactions and physical parameters for special measurement tasks are listed. This serves as a holistic procedure method of hints for the setup of future measurements.
KEYWORDS – Chassis dyno, Road-to-Rig, X-in-the-Loop, Environment, Driver