Control System Ques & Ans (H001)

In force voltage analogy velocity in mechanical system is equivalent to ___ in electrical system.

(a) Charge       (b) Current
(c) Inductance  (d) Capacitance

The transfer function is defined only for

(a) Linear time-invariant system        (b) Nonlinear time-invariant system 

(c) Nonlinear time variant system      (d) Both a and b

Reduce the block diagram and find out the transfer function.

A system has transfer function (1-s)/(1+s). It is known as

(a) Low-pass system                (b) High-pass system
(c) All-pass system                  (d) None of these

The root locus starts from

(a) zeros and ends on poles             (b) poles and ends on zeros
(c) zeros and ends on infinity           (d) poles and ends on infinity

How to find out the angle of asymptotes with the real axis in root locus analysis ?

The open-loop transfer function of a system is given by

  then which of the following is true

(a) There will be a root locus in between -1 and -2

(b) There will be a root locus in between -5 and -2

(c) There will be a root locus in between -5 and -infinity 

(d) Both a and c

If there are x number of poles and y number of zeros then how many root locus branches goes to infinity.

(a) 2x-y                (b) 2y-x
(c) x-y                  (d) x+y

Root locus is the locus of

(a) Open loop poles               (b) Open loop zeros
(c) Closed loop poles             (d) Closed loop zeros

The starting point of root loci are
(a) Open loop poles               (b) Open loop zeros
(c) Closed loop poles             (d) Closed loop zeros

Root loci ends at

(a) Open loop poles               (b) Open loop zeros
(c) Closed loop poles             (d) Closed loop zeros

There is system with transfer function  
                       G(s)H(s)=k(s+3)/(s+1)(s+2)(s+5)

Find the point where the asymptotes of the root locus intersect the real axis
(a) -2.5                 (b) -2
(c) -1.5                 (d) -1

If number of poles is denoted by p and number of zeros is denoted by z then the angle between the adjacent asymptotes in root locus analysis is

(a) 180/(p+z)                 (b) 90/(p-z)
(c) 360/(p+z)                 (d) 360/(p-z)


Answers

1-b,  2-a,  3-a,  4-b,  5-b,  6-d,  7-b,  8-c,  9-c,  10-a  

11-b,  12-a,  13-d

Open loop and closed loop system

Open loop control system

Advantage

• Sensors are not needed to measure variable as feedback is absent.
• It is easier to build and less expensive.
• It is more stable as feedback is absent.

Disadvantage

• It has no accuracy.
• If non-linearity is present in the input then it cannot be reduced because of absent of feedback.
• More sensitive to system parameter variation.
• Transient response and steady state response cannot be controlled effectively.

Example:

• An automatic faster
• Control of furnace for coal heating
• An electric washing machine

 Closed loop control system

   Advantage

• It gives more accuracy.
• If non-linearity is present in the input then it is reduced by the feedback.
• It is less sensitive to system parameter variation.
• Transient response and steady state response can be controlled more conveniently.

    Disadvantage

• Sensors are needed as feedback is present.
• It is very difficult to build.
• It is comparatively less stable. 

     Example:

• Pressure control system
• Speed Control System
• Robot Control System