6. System Interconnections
This chapter introduces the tools needed to construct a composite system based on a given system topology and descriptions of the blocks. SeriesConnect, ParallelConnect, FeedbackConnect, and StateFeedbackConnect perform elementary interconnections; GenericConnect handles these as well as more convoluted cases. The auxiliary functions Subsystem, DeleteSubsystem, and MergeSystems provide a means of manipulating system contents other than interconnections. All the functions accept (and operate analogously on) continuous- and discrete-time objects, but the systems to be connected must be in the same domain (and sampled at the same rate, if discrete-time) to produce a meaningful result. It is, therefore, the responsibility of the user to perform the necessary conversions prior to calling the interconnecting functions.
The interconnection procedures do not necessarily result in minimal state models, so some model reduction techniques (see Chapter 8) may be appropriate.