Interactive software for dynamic system modeling using linear graphic

摘要

A description is given of Lgraph, which is an interactive, graphical software package for creating, modifying, and reducing linear graphs. Linear graphing, a structured method for formulating and representing lumped-element, linear dynamic system models containing connected single-port energy storage, dissipative, and source elements, and two-port transduction elements, is explained through the example of a simplified, quarter-body car suspension. Lgraph enables the user to place elements from several domains in a connected graph, and then computes and displays elemental equations, constraint (loop and node) equations, and state equations for the dynamic system, all in symbolic form. Its operation is described by a second example, the modeling of a DC servomotor drive system. The procedural algorithms are described. The package was implemented using X Windows graphics and runs on Unix-based engineering workstations.