Control Engineering — Summer 2018

State whether following statements are TRUE or FALSE. Justify your answer with appropriate reason. i. Feedback is sometimes used to improve the sensitivity of a control system. ii. The transfer function is defined only for a linear, time-invariant system. iii. Fixed-time traffic light control system is an example of closed loop control system. iv. In stochastic control system the response is not predictable and repeatable. v. Anegative feedback control system is the one where the output signal is fed back so that it is added to the input signal. vi. In a linear system the response produced by simultaneous action of two different forcing functions is the difference of individual responses. vii. If type-2 system is subjected to unit ramp input, the steady state error would be zero.

Briefly explain complete classification of control system.

i. Determine transfer function for a torsional/rotational mechanical system. ii. Determine the unit step response for a system with transfer function given as: C(s) 1 = . R(s) (s+1)(s2+1)

For the translational mechanical system as shown in figure-1, write differential equations and derive its transfer function X2(s) . U(s)

Prepare mathematical model for the liquid-level system as shown in figure-2, and derive its transfer function Qo(s) . Also draw its block diagram. Q(s) i

i. Define following terms with reference to signal flow graph.

Input or source node b) Loop and c) forward path gain ii. Determine damping condition (un-damped, under damped, critically damped or over damped) for the following systems:

and b) s2+90s+900 s2+30s+225

Reduce the block diagram for the system as shown in figure-3 and obtain its transfer function.

i. With neat sketch explain rule for:

Eliminating blocks in series and b) eliminating blocks in parallel. ii. Derive equation of unit ramp response and unit impulse response for the 1st order system.

Convert the block diagram shown in figure-3 into signal flow graph and obtain its transfer function using mason’s gain formula method.1

Prepare root locus for the unity feedback system for the forward path transfer function k given by G(s) = s(s+1)(s+2)(s+4)

Define following terminologies in reference to transient response specifications of second order system using neat sketch: i. Peak time ii. Rise time iii. Delay time iv. Settling time v. Maximum overshoot vi. Steady state error

Explain boiler feed control system using neat sketch.

Define programmable logic controller. What are the components of PLC? State the Advantages & Disadvantages of it.

State the various types of Industrial controllers and describe any two of them.

With the help of a sketch explain a pneumatic proportional plus integral controller and derive its transfer function.

Briefly explain and derive transfer function for a DC motor.

Explain the construction, working and application of a hydraulic intensifier. Figure-1 Figure-3 Figure-2