Control System-1 Short Question Bank (All Units)

      Vision Institute of Technology, Kanpur

                    Control System-1  short Questions

                                UNIT-1

1. What is meant by a system?
2. What is a command input?
3. Define output
4. What is an actuating signal
5. Define plant
6. List the two types of control systems?
7. List the two types of control systems?
8. The impulse response of a LTI system is a unit step function, then what is the corresponding
9. transfer function
10. For a type one system, what is the steady – state error due to step input.
11. If the Nyquist plot of the loop transfer function G(s) H(s) of a closed-loop system encloses the (−1, jo) point in the G(s) H(s) plane, then what is the gain margin of the system.

                                    UNIT-2

1. What is The transfer function of a phase-lead controller.
2. Define transfer function
3. Define order of the system
4. Give the important characteristics of open loop control system
5. Mention the basic elements of closed loop system
6. Define Laplace transform
7. For what purpose Laplace transform is used in control system?
   ANS. The output of any control system, for any input can be obtained by solving integrodifferential equations. Mathematically it is very difficult to solve such equations in time domain. The Laplace transform of such integral differential equations converts them into simple algebraic equations.
8. What is block diagram?
   Ans. A block diagram of a system is a pictorial representation of the functions performed by each component of the system and shows the flow of signals.

9. What is transmittance?
   Ans. The transmittance is the gain acquired by the signal when travels from one node to another node in the signal flow graph.

10. Define self loop

                                    UNIT-3

1. What are the standard tests signals employed for time domain studies?
2. Define settling time
3. Define peak overshoot.
4. What is transient response?
5. What is steady state response?
6. Give the expression for total time response c(t)
7. Give the mathematical expression for stable operating systems
8. What is meant by stable system?
   Ans. To get the desired output, system must pass through transient period. Transient response must vanish after some time to get the final value closer to the desired value. Such systems in which transient response dies out after some time is called stable systems.

9. Define steady state error.
   Ans. The difference between the desired output and the actual output of the system is called steady state error, which is indicates the accuracy and plays an important role in designing the system.

10. What is positional error coefficient?
11. What is velocity error coefficient?
12. What is acceleration error coefficient?
13. State various time domain specifications.
14. What is acceleration error coefficient?
15. What is meant by type number of the system? What is its significance?
16. Define damping ratio
17. Define damping
    Ans. Every system has the tendency to oppose the oscillatory behavior of the system, which is called damping

18. Define sensitivity of the control system.
    Ans. An effect in the system performance due to parameter variations can be studied mathematically defining the term sensitivity of a control system. The change in a particular variable, due t parameter can be expressed in terms of sensitivity

                                        UNIT-4

1. Define natural frequency.
2. The frequency of oscillations under damping ratio =0 condition is called natural frequency.
3. What is called compensation?
   Ans.To meet independent specifications, a second order system requires to be modified. This modification is termed as compensation. It should allow for high open-loop gains to meet the specified steady state accuracy and yet preserve satisfactory dynamic performance.

4. What are the different compensation techniques?
5. Derivative error compensation.
6. Derivative output compensation.
7. Integral error compensation
8. What is called a proportional plus integral controller
9. Define gain-cross over frequency.
10. Define phase-cross over frequency.
11. Define gain margin G.M. in bode plot
12. Define phase margin
13. How the gain margin and phase margin be improved
    Ans. Easiest way to improve G.M. and P.M. is to reduce the gain. However this increases steady state error and makes the system sluggish. Better methods are available. These methods are adding compensating networks are compensators

14. Define bandwidth
15. List the advantages of bode plots.
16. What is meant by the term corner frequency?

                                    UNIT-5

1. What are minimum phase systems?
   Ans. The minimum phase systems are systems with minimum phase transfer functions. In minimum phase transfer functions, all poles and zero will lie on the left half of S plane.

2. What is meant by frequency response of system?
   Ans .The magnitude and phase relationship between the sinusoidal input and the steady state output of a system is termed as the frequency response. In linear time invariant systems, the frequency response is independent of the amplitude and phase of the input signal.

3. List the frequency domain methods to find the stability of the system
   Ans .The commonly used frequency domain methods to sketch the frequency response of the systems are

(i) Bode plot

(ii) Polar plot

(iii) Nyquist plot

(iv) Nichol‟s chart

4. What are frequency domain specifications?

(a) Resonant peak

(b) Cut-off rate

(c) Resonant frequency

(d) Gain margin

(e) Phase margin

5. How static error coefficients can be determined in bode plots?