Determination of vehicle controllability and stability metrics in a target-oriented virtual chassis development process

Abstract Vehicle chassis development is increasingly performed virtually based on systems engineering approaches. A characteristics-based system engineering approach that is oriented towards the V-model enables the definition, development, monitoring and tracking of overall vehicle characteristics during the vehicle development process. In the early phase of the development process, target ranges for several overall vehicle characteristics must be defined at the top level of the V-model. These target ranges can be derived step-by-step down to the bottom level of the V-model into target ranges for subsystems using target cascading and solution space methods. This allows the design of the various subsystems to be decoupled and the robustness of the designs created to be visualized. The overall vehicle characteristics at top level of the V-model must be measurable and therefore physically based so that they can be calculated in the virtual world with vehicle models. Overall vehicle characteristics can be defined for various domains of vehicle dynamics, with lateral dynamics being one domain and driving safety being one aspect of this. With regard to driving safety, it is important to analyze the nonlinear part of lateral dynamics in particular. As time domain simulations are computing intensive, a more efficient way of calculating overall vehicle characteristics is to be found. Therefore, overall vehicle characteristics are defined based on steady-state and dynamic partial equilibria. A methodology based on the Newton-Raphson method is being developed that enables an efficient and automatic determination of the defined overall vehicle characteristics so that they can be used in the iterative solution space method. The defined overall vehicle characteristics are compared with time domain simulations to show the relevance of the selected characteristics.