Converting a block diagram to a signal-flow graph

 Problem   Convert the block diagram of Figure 5.11 to a signal-flow graph.

Solution   Begin by drawing the signal nodes , as shown in Figure 5.19(a). Next, interconnect the nodes, showing the direction of signal flow and identifying each transfer function . The result is shown in Figure 5.19(b). Notice that the negative signs at the summing junctions of the block diagram are represented by the negative transfer functions of the signal-flow graph. Finally, if desired , simplify the signal-flow graph to the one shown in Figure 5.19(c) by eliminating signals that have a single flow in and a single flow out, such as eqimages/snm05020_p2_.png , and eqimages/snm05020_p2_2.png  .
(Example 5.6, Pages 268-269)

Signal-flow graph development:
a. signal nodes;
b. signal-flow graph;
c. simplified signal-flow graph
(Figure 5.19, Page 268)