Digraph Programs for Multivariable Control

Abstract In order to "see" the signal flow in a multivariable system it is easy to map state space equations into a directed graph (digraph). The paper introduces some programs that can provide a control engineer with qualitative information with regard to decomposition, controllability, pole placement, disturbance rejection, input-output decoupling, and more based on the digraph. Rather than presenting the programs in detail the paper provides an intuitive introduction based on inspection of the digiaph of an IFAC pendulum benchmark problem. The software is made instead available on Internet together with some preliminary documentation. It is written in Matlab v. 4.2b under the DOS operating system. It is under development and voluntary test sites are sought