BEE Bachelor of Electrical Engineering Control System Principles Questions and Answers

Question 1

A control system has a characteristic equation given by s³ + 6s² + 11s + 6 = 0. According to the Routh-Hurwitz stability criterion, what can be concluded about the stability of this system?

Accepted Answer

The system is stable.

Answer

The system has roots in the right-half plane and is unstable.

Answer

The system is marginally stable.

Answer

The system's stability cannot be determined without a root locus plot.

Question 2

An engineer is designing a closed-loop control system for a DC motor's position. After implementing a proportional (P) controller, they observe a persistent difference between the desired final position and the actual final position. Which type of control action should be added to eliminate this steady-state error?

Accepted Answer

Integral (I) control

Answer

Additional proportional gain

Answer

Derivative (D) control

Answer

A feedforward controller

Question 3

For a unity feedback control system, what is the steady-state error for a Type 1 system subjected to a unit step input?

Accepted Answer

Zero

Answer

Infinite

Answer

A non-zero constant

Answer

Dependent on the system's zeros

Question 4

Which of the following correctly defines the phase margin in the context of a Bode plot analysis?

Accepted Answer

The difference between the system's phase angle and -180 degrees at the gain crossover frequency.

Answer

The amount of additional gain required to make the system marginally stable at the phase crossover frequency.

Answer

The phase angle at the frequency where the magnitude plot crosses 0 dB.

Answer

The frequency at which the phase angle is -180 degrees.

Question 5

According to the fundamental rules for constructing a root locus plot for a system with an open-loop transfer function G(s)H(s), where do the branches of the root locus begin (for K=0)?

Accepted Answer

At the open-loop poles of G(s)H(s)

Answer

At the origin of the s-plane

Answer

At the open-loop zeros of G(s)H(s)

Answer

At the closed-loop poles of the system

Question 6

In comparing open-loop and closed-loop control systems, which statement is most accurate regarding their sensitivity to external disturbances and parameter variations?

Accepted Answer

Closed-loop systems use feedback to correct for disturbances, making them less sensitive than open-loop systems.

Answer

Open-loop systems are more complex and expensive but offer better disturbance rejection.

Answer

Both systems are equally sensitive to disturbances, but closed-loop systems are faster.

Answer

Open-loop systems are less sensitive to parameter variations because they do not have a feedback path.

A control system has a characteristic equation given by s³ + 6s² + 11s + 6 = 0.According to the Routh-Hurwitz stability criterion, what can be concluded about the stability of this system?

A control system has a characteristic equation given by s³ + 6s² + 11s + 6 = 0.
According to the Routh-Hurwitz stability criterion, what can be concluded about the stability of this system?