The need for automated formula manipulation in object-oriented continuous-system modeling

Automated formula manipulation is shown to be central to object-oriented continuous-system modeling. Such techniques are needed to (i) solve the causality assignment problem in modeling any kind of energy transducer, (ii) generate the equations that result from the couplings between different objects, (iii) automatically reduce structurally singular models, and (iv) take care of algebraic loops that often result from subsystem couplings, and that also occur from the reduction of structurally singular models. A new tool, Dymola 2.0, is presented that implements all of the aforementioned formula manipulation techniques and can be used to generate state-space models in a variety of different simulation languages (ACSL, DESIRE, and Simmon)