Abstract
Highly competitive market conditions together with very exigent customers made it necessary for the automotive industry to shorten development times while improving quality and introducing new functionalities. The development process of a vehicle is related with the design of components and systems as well as with their interaction within the entire vehicle. Furthermore only diffuse information is available at early design stages.
Simulation techniques have been widely applied since the last decade during the early design phase to deal with these restrictions. Parameter variations, sensitivity analysis and even considerations beyond the physical boundaries (e.g. very high speeds or accelerations) are possible. Furthermore the level of complexity of the used model should harmonize with the development stage and with the task the designer is dealing with. In very early design stages where no specific data of the vehicle exists and fundamental guidelines should be defined for the later design process, very simple models are sufficiently accurate. More complex models are used in later development stages. For example, mass point models are suitable to determine optimized trajectories or limiting curves in cases of collision avoidance maneuvers while full vehicle models can be used to investigate the combined vehicle dynamics (horizontal and vertical). It is worth noting, that the compatibility of the different models must be guaranteed in a successful development process. Nevertheless, this is still a field of investigation and development in the automotive industry.
In this paper, compatible vehicle, system and component models with different complexity levels are compared using the modular modeling and simulation environment developed at the Institute of Automotive Engineering of Graz University of Technology. At vehicle level, quarter, single track (bicycle) and full vehicle models are considered. Passive, semi-active and active suspension systems are investigated. Furthermore, at component level different vertical tire models (e.g. point contact, tire with enveloping model) as well as spring and damper models (linear, nonlinear) are analyzed.
The evaluation of ride comfort and handling behavior during the design process of vehicles with in-wheel motors are presented as example to compare and analyze the different modeling complexity levels. The results give information regarding which model should be used depending on the development stage, the specific task and the desired accuracy.
Keywords: In-wheel motors, modular modeling and simulation, flexible vehicle models, vehicle simulation, ride comfort