The document discusses block diagrams and their utility in control engineering, highlighting how transfer functions can represent interconnected system components graphically. It explains critical concepts like summing points, takeoff points, and the importance of the characteristic equation of closed-loop transfer functions for stability. Additionally, it includes examples and homework assignments related to obtaining transfer functions for multiple input single output systems.

1. ME-314 Control Engineering
Dr. Bilal A. Siddiqui
Mechanical Engineering
DHA Suffa University

2. Block Diagrams and Their Utility
• With transfer functions, it is easy to represent interconnected
components of a system graphically.
• Each transfer function is represented as a block, with inputs
and outputs.
• Output of one subsystem may serve as the input of another
subsystem, and vice versa.

3. Summing, Branch Takeoff Points
• Summing points
• Takeoff points

4. Block Diagram of an Industrial Control
System (Ogata)

5. Block Diagram of a General Close
Loop System

6. Close Loop Transfer Function

7. Characteristic Equation of Close
Loop Transfer Function
Characteristic equation
is important since it
determines stability, as
we will see.

8. Block Diagram Reduction

11. Example

13. Another Example

15. Another Example
Hint: bottom loop does not have feedback. Why?

19. Superposition of Multiple Inputs

20. Multiple Input Single Output
Systems (MISO)

23. HW 3a

24. HW 3b
Obtain transfer function C(s)/R(s)

25. HW 3d
• Obtain expression for C(s) when both R(s) and
D(s) are present