ABSTRACT

A block diagram is an interconnection of symbols representing certain basic mathematical operations in a way that the overall diagram obeys the system’s mathematical model. In the diagram, the lines interconnecting the blocks represent the variables describing the system behavior, such as the input and state variables. Inspecting a block diagram of a system provide new insight into the system’s structure and behavior beyond that available from the differential equations themselves. The chapter shows that graphical models can be used for more general systems than those considered here, including nonlinear blocks, multi-input/multi-output systems, and discrete-time systems. Computer programs for the analysis and design of control systems exist that allow the entry of block diagram models in graphical form. The multiplication of a single variable by a constant is represented by a gain block. It is desirable to reduce the transfer functions of combinations of blocks to rational functions of s in order to simplify the subsequent analysis.