JNTU
JNTU B.Tech II CONTROL SYSTEMS Previous Question Paper (December - 2018 - R16)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit.
Part A
Explain how feedback effects overall gain of the system.
Answer
Feedback reduces the overall gain of a system. For a system with an open-loop gain G(s) and a feedback path H(s), the closed-loop gain T(s) is given by the formula:
In a negative feedback system, the denominator (1 + G(s)H(s)) is typically greater than one, which results in a reduction of the total system gain compared to the open-loop configuration. This reduction in gain is a trade-off made to achieve benefits such as improved stability, increased bandwidth, and reduced sensitivity to parameter variations.
State and explain Mason’s gain formula.
Answer
Mason's gain formula is a mathematical technique used to determine the overall transfer function of a complex signal flow graph. It relates the input and output variables of a system by considering all possible forward paths and feedback loops within the graph.
The formula is given by:
Where:
- Pk is the gain of the k-th forward path.
- Δ is the determinant of the graph, calculated as 1 - (sum of individual loop gains) + (sum of gain products of all possible combinations of two non-touching loops) - (sum of gain products of all possible combinations of three non-touching loops) + ...
- Δk is the cofactor of the k-th forward path, which is the value of Δ for the part of the graph that does not touch the k-th forward path.
What is meant by characteristic equation?
Answer
Sign in to view the complete answer paper.
What are the standard test signals?
Answer
Sign in to view the complete answer paper.
What are the limitations of Routh’s stability?
Answer
Sign in to view the complete answer paper.
What are frequency domain specifications?
Answer
Sign in to view the complete answer paper.
Explain Lag compensation.
Answer
Sign in to view the complete answer paper.
What is the difference between polar plot and Nyquist plot?
Answer
Sign in to view the complete answer paper.
What are the properties of state transition matrix?
Answer
Sign in to view the complete answer paper.
What is meant by state in control system?
Answer
Sign in to view the complete answer paper.
Part B
Derive an expression for the transfer function of an armature controlled DC servo motor.
Answer
Sign in to view the complete answer paper.
Obtain the transfer function for the following mechanical translational system figure 1.
Answer
Sign in to view the complete answer paper.
Obtain the transfer function for the following mechanical translational system figure 2.
Answer
Sign in to view the complete answer paper.
Write the equations for time domain specifications of a standard second order system with unit step input.
Answer
Sign in to view the complete answer paper.
Explain the effect of Proportional control action on the performance of a second order system.
Answer
Sign in to view the complete answer paper.
Consider the system shown in the Figure 3. With switch K open, determine the damping factor and the natural frequency of the system. If a unit ramp input is applied to the system, find the steady state output. Take KA = 5. The damping factor is to be increased to 0.7 by including a derivative output compensation. Find the value of kt to achieve this. Find the value of undamped natural frequency and the steady state error due to a unit ramp input.
Answer
Sign in to view the complete answer paper.
A unity feedback system has an open loop function G(s) = K / (s(s^2 + 3s + 10)). Make a rough sketch of root locus plot by determining the following (a) Centroid, number and angle of asymptotes (b) angle of departure of root loci from the poles (c) Breakaway points if any.
Answer
Sign in to view the complete answer paper.
Sketch the Bode plot for the following transfer function and determine the system gain K for which the magnitude plot crosses the 0 db line at ω = 15 rad/sec. G(s) = K / (s(s+1)(1+0.1s)(1+0.01s)).
Answer
Sign in to view the complete answer paper.
Draw the complete Nyquist plot for the following open loop transfer function G(s)H(s) = 2(s+0.25) / (s^2(s+1)(s+0.5)). If the system is unstable, how many poles of the closed loop system are in the right half of s-plane?
Answer
Sign in to view the complete answer paper.
Draw the electrical circuit diagram that represents the Lead-Lag compensator and explain in detail.
Answer
Sign in to view the complete answer paper.
Consider the following polar plot shown in Figure 4. If now a pole at origin and a pole at s = -1/T2 are added, sketch the polar plot.
Answer
Sign in to view the complete answer paper.
Design a lag lead compensator for the unity feedback system with G(s) = K / (s(s+1)(s+2)) and satisfying the specifications, Kv = 10 sec^-1, φpm = 50° and B.W > 2 rad/sec.
Answer
Sign in to view the complete answer paper.
Explain various methods of evaluation of state transition matrix.
Answer
Sign in to view the complete answer paper.
Obtain the transfer function for linear time invariant system and also draw the state model.
Answer
Sign in to view the complete answer paper.
Determine the state and output equations in vector matrix form for the system whose transfer function is given by G(s) = (s+2) / (s(s^2 + 4s + 3)).
Answer
Sign in to view the complete answer paper.