Control Systems - May 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) What is damping ratio? Show the location of roots in s-plane for different values of damping ratio.(5 marks) 1 (b) From the pole-zero plot given below obtain:
(i) Transfer function.
(ii) Order of the system.
(iii) Characteristic equation.
(iv) DC gain of the system.
(5 marks) 1 (c) Find the transfer functions from the signal flow graph given below:
(5 marks) 1 (d) 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) 2 (a) Find C using block diagram reduction rules.
(10 marks) 2 (b) Sketch the root locus for a unity feedback control system with
G(s) = K/[s(s+3)(s+5)] and determine -
(i) K for marginal stability.
(ii) Frequency of oscillation for marginal stability.
(iii) K for damping ratio of 0.5.(10 marks) 3 (a) Derive the time response expression for a second order control system subjected to unit step input.(10 marks) 3 (b) What is stepper motor? Mention its types. Explain one type of stepper motor with neat diagrams.(10 marks) 4 (a) Define sensitivity of a control system. Derive the sensitivities S_H<supt< sup=""> and S_G<supt< sup=""> of a feedback control system where T is closed loop gain, H is the feedback gain and G is the open loop gain of the system.</supt<></supt<></span>(10 marks) 4 (b) For the transfer function given below:
G(s)H(s) = 48(s+10)/[(s(s+20)(s²+2-4s+16)]. Find
(i) Static position error co-efficient.
(ii) Static velocity error co-efficient.
(iii) Static acceleration error co-efficient.
(iv) Steady state error if the input to the system is unit step.(10 marks) 5 (a) Sketch the bode plot for a system with open loop transfer function:
G(s)H(s) = 30/[s(1+0.5s)(1+0.8s)] and comment on stability.(10 marks) 6 (b) Find the overall transmittance using Masons gain Formula.
(10 marks)

Write short notes on:-

7 (a) Nyquist stability criteria.(10 marks) 7 (b) Error compensation techniques.(10 marks)