The signal flow diagram for a certain feedback control system is shown in the figure. Now consider the following set of equations for the nodes 1. x2 = a1x1 + a9x3 2. x3 = a2x2 + a8x4 3. x4 = a3x3 + a5x2 4. x5 = a4x4 + a6x2 Which of the following is correct?
The signal flow diagram for a certain feedback control system is shown in the figure. Now consider the following set of equations for the nodes 1. x2 = a1x1 + a9x3 2. x3 = a2x2 + a8x4 3. x4 = a3x3 + a5x2 4. x5 = a4x4 + a6x2 Which of the following is correct? Correct Answer 1, 2 and 4
Concept:
Terminology:
Node: A node in SFG represents a variable in the system I.e. number of nodes is equal to no of variables.
Input node: The node that has only incoming branch
Output node: The node that has only outgoing branch
Forward path: The path that connects the input node with the output node such that no node is repeated.
Loop: A loop is a close path that starts and ends at the same node such that no node is repeated.
Analysis:
We just need to observe the incoming branch at the respective node.
From the above concept:
x2 = a1x1 + a9x3
x3 = a2x2 + a8x4
x4 = a3x3 + a7x4
x5 = a4x4 + a6x2
Only (3) is incorrect.

