VehicleDynamics

Purpose

The Vehicle Dynamics Library, or VDL, is intended for vehicle dynamics analysis related to mechanical design and control design of automotive chassis. Handling behavior is the primary target, but the library is also well suited for studies of other vehicle properties. The library can be used to analyze partial as well as complete vehicles. Models are designed in a way that is similar to the structure of real vehicle assemblies. The library is hierarchically organized and grouped into intuitive subpackages. The focus is on chassis, wheels, driver, and road but basic models for e.g. engines, transmissions, drivelines, and brakes are supplied to offer full vehicle modeling and simulation capability in a single environment. If more detailed models are desired, then the multi-engineering capabilities of Modelica allow for convenient integration of e.g. pneumatic, hydraulic or electronic components from other libraries. Custom built components are also easily integrated in the models.

Modeling and simulation

Many simulation tools are essentially user-interfaces for setting the parameters of fixed simulation models. This means that the actual equations that describe the model are impossible, or difficult, to modify by users.Vehicle Dynamics Library offers a different approach and provides much more flexibility. In combination with a simulation tool this Modelon library is a complete modeling and simulation tool. This is important to understand, since it implies that the working procedure is slightly different and contains some additional steps:

• Build models that describe the phenomena of interest,
• Tune the model parameters,
• Use the models to set up an experiment that exposes the phenomena of interest,
• Simulate the experiment,
• Analyze the results

Vehicle Dynamics Library contains a large set of pre-defined models and templates that makes most modeling tasks straightforward. For many standard tasks it is possible to use the library in the same way as a pure simulation tool, i.e. it is sufficient to choose the right model, define all parameters and start the simulation.

Flexibility with prudence

It is possible for users to modify and extend most of the models in the library, and also to complement the library with custom models. It is also possible to mix with model components from other libraries. This is one of the major benefits of describing models using a high-level modeling language like Modelica. Customization of models and components can be done either from the graphical user interface and diagram view, or, for advanced users, by typing Modelica source code. There is also great flexibility in setting up experiments and analyzing results. The flexibility implies great freedom for users to define models and experiments, but may also require more attention to details and understanding.

Modelon libraries

All Modelon libraries are compatible and can be combined to solve specific engineering design tasks. For more detailed studies of for example brake systems, both Hydraulics Library and Pneumatics Library can be used together with VDL. Furthermore, Engine Dynamics Library contains detailed models of combustion engines and can be integrated with vehicle models from VDL.