Integrated Development of Vehicle Dynamics Demonstrated on the New Bmw 3 Series

Abstract

This paper describes BMW’s new integrated approach for chassis development. The chassis optimization process includes the evaluation of requirements ranging from customer expectations to component parameters, as well as testing and validation. BMW developed a novel systematic methodology for combining the various design tools and methods. The process starts with an assessment of customer requirements based on subjective criteria and objective measurements. BMW uses a standardized set of objective criteria. This makes it possible to compare vehicle performance through history and across the competitors. Based on these criteria and subjective impressions the goals are defined. These goals are then detailed into component requirements. For this purpose, iterative development and validation steps are planned together in order to refine the requirements, basing the new design on the results of the previous step. These are determined through simulation, with a test-rig, or through vehicle testing. This paper presents examples of chassis elastokinematics, the steering properties, and the vertical suspension properties. The objective goals from the first step are mapped to passive subsystems of the vehicle, such as suspension and steering, but also to control systems as well. After the layout process, tests of the vehicle hardware are performed and measured against the goals obtained from the customer requirements. The virtual development process is supported by scalable models and systems, starting with an expert system that demonstrates the dependencies between subsystems, components and customer needs. A fast concept model provides a convenient way to detail the requirements to subsystems and a subsequent transfer to further car derivates. Finally, more complex MBS and FEM simulations are performed to optimize the component parameters. These steps result in an effective development process, combining the strengths of the hardware and virtual worlds. BMW uses these methods to develop derivates primarily virtually while nonetheless ensuring outstanding driving dynamics.

F2012-G06-008.