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- Automatic Control System - ACS
- 2018
- PYQ
**Biju Patnaik University of Technology BPUT - BPUT**- Mechanical Engineering
- B.Tech
**26 Views**- Uploaded 4 months ago

Registration No : Total Number of Pages : 03 B.Tech PME7D013 7th Semester Regular Examination 2018-19 AUTOMATIC CONTROL SYSTEM BRANCH : MECH Time : 3 Hours Max Marks : 100 Q.CODE : E462 Answer Question No.1 (Part-1) which is compulsory, any EIGHT from Part-II and any TWO from Part-III. The figures in the right hand margin indicate marks. a) Part- I Short Answer Type Questions (Answer All-10) Find the transfer function of the control system shown in Fig. 1. b) Fig. 1. What is the effect of negative feedback control on sensitivity of a system? c) For a unity feedback system having G(s) Q1 d) e) dt 2 g) h) 64 , find the time at which second s(s 8) undershoots will occur. What is the inference regarding system stability when the system characteristic equation has multiple poles on the jω - axis in s-plane? Find the damped natural frequency for a closed loop system represented by differential equation d 2 c(t) f) (2 x 10) 8 dc(t) 64[r(t) c(t)] dt Where c(t) is the displacement of the output shaft and r(t) is the displacement of input shaft. Is there any modification in rules of construction of root locus used for construction of root contour? What are the advantages and disadvantages of frequency response analysis in comparison to time domain analysis? Find how many unstable roots are there for q(s) s 5 4s 4 8s 3 9s 2 6s 2 i) j) What is principle of argument? What do you mean by cut off rate and cut off frequency? Part- II Focused-Short Answer Type Questions- (Answer Any Eight out of Twelve) Q2 a) The unity feedback system is characterized by G(s) K . Find the gain K, so that s(s 10) the system will have a damping ratio of 0.5. For this value of K, Determine settling time, peak overshoot and time at peak overshoot for a step input. (6 x 8)

b) For a unity feedback control system the open loop transfer function is G(s) i. c) 100(s 5) s(s2 2s)(s 6) Find Kp, Kv, Ka. ii. Find ess due to an input described by ( ) = 1 + 7 + The open loop transfer function of a control system is given by ( ) ( )= d) f) + 2 + 2) Sketch the root locus. The characteristic equation of a feedback control system is + 20 e) ( + 15 +2 + =0 Determine the range of K for the system to be stable. Can the system be marginally stable? If so, find the required value of K and the frequency of sustained oscillation? Derive the generalized error series and the generalized error coefficients. Check the stability of the characteristic equation and find the number of roots of this equation with positive real part, zero real part and negative real part. +4 +3 − 16 − 64 − 48 = 0 g) Obtain the transfer function of an armature controlled DC servomotor. h) For a feedback system as shown in Fig.2, find k1 and k2 so that peak overshoot of the system is 1.6% and the corresponding peak time is 1.2 second. k1 s(s 3) i) Fig. 2 Explain PID Controllers and their applications to feedback control systems. j) Explain Force-Voltage and Force-current analogy. k) Obtain the expression for unit step response of an under damped second order system and also obtain the expressions for rise time. Explain the effect of regenerative and degenerative feedback on control system. l) Part-III Long Answer Type Questions (Answer Any Two out of Four) Q3 Define gain margin, phase margin, phase crossover frequency and gain crossover frequency. Draw the Bode plot for the transfer function and comment on stability. ( )= 242( + 5) ( + 1)( + 5 + 121) Also find out the gain margin, phase margin, phase crossover frequency and gain crossover frequency. (16)

Q4 Evaluate (C/R) by using block reduction techniques for a system whose block diagram representation is shown in Fig.3. (16) Fig. 3. Also Evaluate (C/R) by using signal flow graph. Q5 Draw the mechanical equivalent network and write the differential equations governing the behavior of the mechanical system shown in Fig. 4. (16) Fig. 4. Also obtain the force-voltage and force-current analogies for the mechanical system shown in Fig. 4. Q6 The open-loop transfer function of a control system is given by 1 ( ) ( )= (1 + 0.2 )(1 + 0.05 ) Draw the Nyquist plot and comment on the stability of the closed-loop system. Also explain about Constant M-circle and N-circle. (16)

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