Control Systems - Dec 2013

Electronics & Telecomm. (Semester 4)

TOTAL MARKS: 80
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks. 1 (a) Define sensitivity of a control system. How can we reduce the sensitivity of a closed loop system.(5 marks) 1 (b) Explain Hurwitz stability criterion and its disadvantages.(5 marks) 1 (c) Define the following terms related to second order system subjected to unit step input.
(i) Rise time
(ii) Peak time.
(iii) Peak overshoot
(iv) Delay time.
(v) Settling time.(5 marks) 1 (d) What are the advantages of a Nyquist plot.(5 marks) 2 (a) If the second order control system has transfer function
F(s) = s² + 24s + 9.
If a step input is applied to it, determine time domain specifications. Also sketch time response.(10 marks) 2 (b) Find the range of K to make the system stable for a unity feedback system.
(10 marks) 3 (a) Determine the transfer functions C/R₁ and C/R₂ from the given system below. Also find C/R.
(10 marks) 3 (b) Find the transfer function of the following system using signal flow graph.
(10 marks) 4 (a) Draw the root locus for the system with
G(s)H(s) = K/[s(s+3)(s+6)]. Obtain the value of K when ?=0.6 from root locus. Also determine the value of K for marginal stability and critical damping.(10 marks) 4 (b) For a unity feedback system: G(s) = 200/[s(s+8)] and r(t)=2t, determine steady state error. If it is desired to reduce the existing error by 5%, find new value of gain of system.(10 marks) 5 (a) A unity feedback system has a loop gain
G(s)H(s)=60/[(s+4)(s²+2s+5)]. Determine the system stability using Nyquist plot.(10 marks) 5 (b) Compare open loop control system and closed loop control system with at least 3 examples.(10 marks) 6 (a) Use Bode plot to determine the frequency response of system. H(s)=1 and
(10 marks) 6 (b) A unity feedback control system has
G(s) = K/[(s+4)³]. Determine the range of K for system stability.(10 marks)

Write shorts notes any two of the following:-

7 (a) Stepper motor construction and its applications in control system.(10 marks) 7 (b) State variable model with an example.(10 marks) 7 (c) Error compensation techniques.(10 marks)