Similarities in Circuit and Multibody Systems Modeling

Abstract

Circuit simulation as well as multibody system simulation have been widely used during the last decades. Automatically generated models are known to lead to differential‐algebraic equations (DAEs) with higher index in both cases. Whereas multibody system models lead to DAEs of index 3, circuit models have usually index 2. Nevertheless, there is a close connection between oth models. We show here, that a simple change in the circuit modelling process leads to DAEs of index 3 with the same structure as multibody system models have. Furthermore, we present a change in the modelling process of multibody systems that provides DAEs of index 2, similar to the systems known from circuit modeling. An extension of this index reduction process allows even an index‐1 DAE description for circuit systems as well as for multibody systems. The most interesting point is here that these modeling steps avoid computations of additional (hidden) constraints. Furthermore, the original contraints are kept, hence the index reduced modell does not suffer from drift effects.