# The Design Problem

The Design Problem

1. What should be the nature of bandwidth for a good control system?

a) Large
b) Small
c) Medium
d) All of the mentioned

Explanation: Bandwidth is defined as the difference in the highest frequency and lowest frequency and bandwidth must be large for the good control system and for higher bandwidth noise is also large.

2. Which system exhibits the initiation of corrective action only after the output gets affected?

a) Feed forward
b) Feedback
c) Both a and b
d) None of the mentioned

Explanation: Feedback is the process in which the output of the system is desired by comparing the output with the input and with the feedback system exhibits the initiation of corrective action only after the output gets affected.

3. A good control system should be sensitive to __________

a) Internal disturbances
b) Environmental parameters
c) Parametric variations
d) Input signals (except noise)

Explanation: A good control system is the system with high speed of response and steady state error must be less and bandwidth should be large and noise must be very low and must be sensitive to parametric variations.

4. What is the value of steady state error in closed loop control systems?

a) Zero
b) Unity
c) Infinity
d) Unpredictable

Explanation: Steady state error is the error which is the difference in the final output to the desired output and the value of steady state error for the good control system must be zero.

5. Into which energy signal does the position sensor convert the measured position of servomotor in servomechanisms?

a) Mechanical
b) Electrical
c) Thermal
d) Light

Explanation: In mechanical system the sensors are used in which the mechanical motion is converted into electrical energy and generally in mechanical system position sensor convert the measured position of servomotor in servomechanism.

6. Which among the following controls the speed of D.C. motor?

a) Galvanometer
b) Gauss meter
c) Potentiometer
d) Tachometer

Explanation: D.C. motor is the motor which operates with the direct current as in the construction of DC motors slip rings not commutators and tachometer control the speed of DC motor.

7. Which among the following represents an illustration of closed loop system?

a) Automatic washing machine
b) Automatic electric iron
d) Electric hair drier

Explanation: Closed loop control system is the system with the positive or negative feedback and this is made so as to avoid the disadvantages of open loop control system and in the above options automatic washing machine represents closed loop system.

8. Which notation represents the feedback path in closed loop system representation?

a) b(t)
b) c(t)
c) e(t)
d) r(t)

Explanation: Feedback can be positive and negative and feedback is so used to reduce the error of the system by comparing the final output with the desired output and reducing the error and this error is denoted with the symbol as e(t).

9. Which among the following is not an advantage of an open loop system?

a) Simplicity in construction & design
b) Easy maintenance
c) Rare problems of stability
d) Requirements of system re-calibration from time to time

Explanation: Open loop system is the system with no feedback and the parameter variations in the open loop system are more as compared to the closed loop system and the system has to be re-calibrated as per the requirement as automatic calibration is not present in this system.

10. Which terminology deals with the excitation or stimulus applied to the system from an external source for the generation of an output?

a) Input signal
b) Output signal
c) Error signal
d) Feedback signal