Integration and synchronization of discrete formalisms and continuous models in Modelica

Many complex technical systems such as airplanes or chemical plants consist of hybrid physical components and purely discrete controllers. In order to aid the design process of such systems, some requirements have to be met as closely as possible: the hybrid physical and the discrete components have to be modeled vividly, the resulting components of the model have to be integrated intuitively into a complete model, and this model has to be simulated efficiently. Numerical integration and discrete-event simulation have to be synchronized. We discuss how the object-oriented modeling language Modelica meets these requirements.