Question

For closed loop control system operation :
A. Controller generates control signal
B. Error signal is produced
C. Output is sensed by sensor
D. Reference input is compared Choose the correct answer from the options given below :

• A. A, B, C, D
• B. D, B, C, A
• C. D, A, B, C
• D. D, B, A, C

Hint:

Closed loop control sequence: \[ \text{Compare input} \rightarrow \text{Generate error} \rightarrow \text{Sense output} \rightarrow \text{Controller action} \]

Answer 1

The Correct Option is B

Concept: A closed loop control system continuously compares actual output with desired input and automatically corrects the error. The sequence of operation generally follows:
• Compare reference input,
• Generate error signal,
• Sense output,
• Generate control action. Feedback is the key feature of closed loop systems.

Step 1: Understanding reference comparison. The first operation is comparison between: \[ \text{Reference input} \] and \[ \text{Feedback signal} \] Thus: \[ D \] comes first.

Step 2: Generation of error signal. After comparison: \[ e(t)=r(t)-c(t) \] where:
• \(r(t)\) = reference input,
• \(c(t)\) = feedback output. Thus: \[ B \] comes next.

Step 3: Sensing the output. The system output is continuously monitored using sensors or feedback elements. Hence: \[ C \] is the next step.

Step 4: Controller generates control signal. Finally the controller processes the error and generates appropriate control action. Thus: \[ A \] comes last.

Step 5: Writing the correct sequence. Hence the correct order is: \[ D,\;B,\;C,\;A \] Therefore the correct option is: \[ \boxed{(2)} \]